GPA Standard 2286-95Tentative Method of Extended Analysisfor Natural Gas and Similar GaseousMixtures by Temperature ProgrammedGas ChromatographyAdopted as a Tentative Standard 1986Reprinted 1989, 1991, 1995Revised 1995Reprinted 1997, 1998, 1999Gas Processors Association6526 East 60th StreetTulsa, Oklahoma 74145DISCLAIMERGPA publications necessarily address problems of a general nature and may be used by anyone desiring to do so. Every effort has been made by GPA to assure accuracy and reliability of the information contained in its publications. With respect to particular circumstances, local, state, and federal laws and regulations should be reviewed. It is not the intent of GPA to assume the duties of employers, manufacturers, or suppliers to warn and properly train employees, or others exposed, conceming health and safety risks or precautions.GPA makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict, or for any infringement of letters of patent regarding apparatus, equipment, or method so covered.Tentative Method of Extended Analysis for Natural Gas and Similar GaseousMixtures by Temperature Programmed Gas Chromatography1. SCOPE1.1 This method covers the determination of the chemical composition of natural gas and similar gaseous mixtures within the ranges listed in Table I. In cases where peaks are known to contain one or more components, groupings are shown in Table I and also again in Figure 4. Improved results for Btu content over those obtained using GPA 2261 will not necessarily be achieved. This method is intended for use with rich gas systems and in situations where the heptanes plus compositional breakdown is desired.1.2 Components sometimes associated with natural gases, ie., helium, carbon monoxide and hydrogen are excluded from the main body of the method. These components are determined and made a

part of the complete compositional data by following special techniques outlined in Appendix B.NOTE 1--Hydrogen sulfide is eluted in a well defined peak between ethane and propane on the suggested partition column described in 3.1.4. For further discussion of the hydrogen sulfide content in natural gases see Appendix B.2. SUMMARY OF METHOD2.1 Components to be determined in a gaseous sample are physically separated by Gas Chromatography and compared to calibration data obtained under identical operating conditions.Set volumes of sample in the gaseous phase are charged by gas sample valves at designated times to three different packed column systems, effectively splitting the analysis into three sections. The first section separating oxygen, nitrogen and methane is tied mathematically to the second section which separates methane through normal pentane. The third section which separates the components eluting from iso-pentane through tetradecane (listed in Table I) are in turn tied to the second section by the common components iso and normal pentanes. Components in section one are separated under isothermal conditions on an adsorption type column and detected by thermal conductivity. The second section of the analysis is taken from a new sample charged to a partition-type column held isothermally for six minutes and then finished by a temperature program. This column effluent passes through a splitter which permits carbon dioxide and hydrogen sulfide to be detected by thermal conductivity and the methane through pentane by hydrogen flame ionization methods. At the same time as section two components are passing through the partition column a third column system is charged with a fresh sample using the same temperature program to yield a breakdown of the components from iso-pentane to the tetradecanes with detection on a second flame ionization unit. (See suggested flow system in Figure 1.) Twelve programmable open collector transistor switch closures are required to perform the necessary valve operations in this method.NOTE 2--The TCD and FID may be run in series if desired instead of using an effluent splitter.NOTE 3--The times listed in this method are for informational purposes only and may vary with changes in operating parameters.rI ~ TcI II 1-'i/2 in Chmmosorb,~ I[ lo~ (e

I Effluent SplitterII Side AI-]Side BI Col. 2 ~-- ---.. ~ ~. Cot. 1[ f Si[Icome ~ lr 6P V3 • ~" Mol Sievo~I ~Composite Col ~ ur ,= 13'/* COL )Gas Sample Loop ~ i ~ ~ J Gas Sample LoopI CL Helium In.•~1 ~ I ' l J ManometerVacuum Sourceu ~ ; Gas Sample Out; Gas Sample InFigure 1 - Suggested Flow System Using an Effluent Splitter.Table INatural Gas Components and Range of Components CoveredPeak Conc. Range Peak Conc. RangeNumber Component Mol % Number Component Mol %Oxygen 0.005 - 20 16 lc,2t,4-Trimethylcyclopentane 0.001 - 2Nitrogen 0.005- 100 lc,2t,3-TrimethylcyclopentaneCarbon Dioxide 0.005 - 100 17 2,3,4-Trimethylpentane 0.001 - 2Methane 0.001 - 100Ethane 0.001 - 100 18 Toluene 0.001 - 2Hydrogen Sulfide 0.10 - 100 2,3-DimethylhexanePropane 0.001 - 100 19 2-Methylheptane 0.001 - 2Iso-Butane 0.001 - 10 4-Methylheptanen-Butane 0.001 - 10 3-Methylheptane1 iso-Pentane 0.001 - 5 20 3,4-Dimethylhexane 0.001 - 22 n-Pentane 0.001 - 5 lc,2c,4-Trimethylcyclopentane3 2,2-Dimethylbutane 0.001 - 5 lc,3-Dimethylcyclohexane4 2-Methylpentane 0.001 - 5 lt,4-Dimethylcyclohexane2,3-Dimethylbutane 21 1,1-Dimethylcyclohexane 0.001 - 25 3-Methylpentane 0.001 - 5 1-Methyl-cis-3-ethylcyclopentaneCyclopentane 22 1-Methyl-trans-2-ethylcyclopentane 0.001 - 26 n-Hexane 0.001 - 5 1-Methyl-l-ethylcyclopentaneMethylcyclopentane 23 n-Octane 0.001 - 22,2-Dimethylpentane 1 t,2-Dimethylcyclohexane7 2,4-Dimethylpentane 0.001 - 2 24 lc,2c,3-Trimethylcyclopentane 0.001 - 22,2,3-Trimethylbutane 25 lc,2-Dimethylcyclohexane 0.001 - 2

8 Benzene 0.001 - 2 2,5-Dimethylheptane3,3-Dimethylpentane 26 3,5-Dimethylheptane 0.001 - 29 Cyclohexane 0.001 - 2Ethylbenzene10 2-Methylhexane 0.001 - 2 1,3-Dimethylbenzene2,3-Dimethylpentane 27 1,4-Dimethylbenzene 0.001 - 23-Methylhexane 2,3-Dimethylheptane11 1,1-Dimethylcyclopentane 0.001 - 2 3,4-Dimethylheptanelt,3-Dimethylcyclopentane 28 2-Methyloctane 0.001 - 21 c,3-Dimethylcyclopentane 0.001 - 2 3-Methyloctane12 1 t, 2-Dimethylcyclopentane 29 1,2-Dimethylbenzene 0.001 - 23-Ethylpentane 30 n-Nonane 0.001 - 213 n-Heptane 0.001 - 231 Decanes 0.001 - 1Methylcyclohexane 32 Undecanes 0.001 - 114 2,2-Dimethylhexane 0.001 - 21,1,3-Trimethylcyclopentane 33 Dodecanes 0.001 - 1Ethylcyclopentane 34 Tridecanes 0.001 - 115 2,4-Dimethylhexane 0.001 - 2 35 Tetradecanes 0.001 - 12,5-DimethylhexaneCAUTION: Peak identification and component groupings are based on the specific column arrangement and operating conditionsused in the development of this method.2.2 An equally acceptable method using a packed column/capillary system is described in Appendix A. Use of a capillarycolumn provides a more detailed characterization of the hexanesplus fraction identifying more individual components thanpacked columns.3. APPARATUS3.1 Chromatograph--Any gas chromatograph may be used which has the following specifications:3.1.1 Detectors--The instrument should be equipped with thermal conductivity detection and dual flame ionization with dual electrometers.3.1.2 Sample Valves--Valves capable of introducing gas volumes up to 0.5 ml will normally be required. The sample volume should be reproducible such that successive runs agree to +0.5% of the counts on each component peak.NOTE 4---The sample size limitation of O.5 ml or smaller is selected with the linearity of detector response and efficiency of the column separation in mind. Larger samples may occasionally be used to improve measurement accuracy in low concentration components.

3.1.3 Adsorption Column (Column 1)--This column must completely separate oxygen, nitrogen and methane by returning to the baseline after each peak. Figure 2 shows an example chromatogram obtained using an acceptable adsorption column.2=EColumn - 12 ft. 13X Mol SieveTemperature - 60°CInlet Pressure - 25 psigSample Size - 0.25 ccType Detector - Thermal ConductivityCarrier Gas - Helium1!Figure 2 - Separation of Oxygen, Nitrogen and Methane.NOTE 5--The preparation of a suitable adsorption column to perform this separation is described in Appendix C.1.3.1.4 Partition Column (Column 2)---This column must separate the hydrocarbons methane through pentanes, and nonhydrocarbons nitrogen and/or air, carbon dioxide and hydrogen sulfide. All peaks must be completely resolved with a return to baseline following each peak. Figure 3 shows an example chromatogram obtained using a suitable partition column to separate these components.NOTE 6--The preparation of a suitable partition column to perform this separation is described in Appendix C.2.3.1.5 Extended Analysis Packed Column (Column 3)—This column must separate hydrocarbons, pentane through tetradecane. Principal components separated are shown in TableI. The column packing must be capable of withstanding temperature programming to 170 °C. Figure 4 shows an example chromatogram obtained using a suitable extended analysis column to separate these components.NOTE 7 The preparation of a suitable extended analysispacked column to perform this separation is described inAppendix C-3.3.1.6 Attenuator--The chromatograph should be equippedwith an attenuator to control the signal manually, if needed.However most modern computing integrators have the ability toprogram the attenuation of the signal automatically and thisprocedure is strongly recommended.3.1.7 Temperature Control--During the iso-thermal part ofthe method the analyzer columns shall be maintained at atemperature within +0.2°C of the required temperature. Thetemperature rise versus time must be checked periodically to

determine that the program is repeatable. Care should be takenthat the upper limit of the program never exceeds the maximumrecommended temperature limit of the materials used in thecolumn packings.3.2 Carrier Gas--Pressure reducing and flow controldevices shall provide a flow of helium or other suitable carriergas to pass through the chromatographic columns at rates notvarying more than +0.5% during the sample and referencestandard runs while in the isothermal mode.3.3 Recording Instruments--Either strip-chart recorders orelectronic integrators with printer-plotters should be used todisplay and measure the peaks as they pass through thedetectors. A chromatogram provides an evaluation of instrumentperformalace during the course of the run.TCD Signal Plot FID Signal PlotColumn - Silicone CompositeTemperature - Programmed60°C - 170°CInlet Pressure - 50 psigSample Size - 0.25 ccType Detector - See Fig. 3Carrier Gas - HeliumFigure 33Column - 15 ft. UCL-45Temperature - Programmed60°C - 170°CInlet Pressure - 80 psigSample Size - 0.25 ccType Detector- Flame IonizationCarrier Gas - Heliumllll/l I Ij~I ~g IFigure 4.3.3.1 Recorders--Recorders shall be strip-chart types witha full range scale of 1 mv and a response time of 1 second.Minimum chart speed is recommended to be 1 cm/min andmaximum speed 10 cm/min and minimum chart width 10 cm.3.3.2 Integrator~Computers--Wide range, 0-1 volt/0-10 volt,with both printing and plotting capabilities, baseline trackingand tangent skim peak detection. Integrator/computers shouldhave sufficient memory to handle the large number of

components and have a minimum of 12 programmable externalevent relays.3.4 Manometer--May be either U-tube type or well typeequipped with an accurately graduated and easily read scalecovering the range 0 to 900 mm (36 in.) of mercury or larger.The U-tube type is useful with the GPA Gas Standard, since itpermits filling the sample loop with up to two atmospheres ofsample pressure, thus extending the range of all components.The well type inherently offers better precision and is preferredwhen calibrating with pure components. Samples can be enteredup to one atmosphere of pressure. With either manometer, themm scale can be read more accurately than the inch scale.Caution should be used in handling mercury because of its toxicnature. Avoid contact with the skin. Wash thoroughly after anycontact.4. LINEARITY CHECK PROCEDURE4. 1 For any specific chromatograph, the linear range of themajor components of interest must be determined on theirrespective detectors. The linear range should be established forany new chromatograph and re-established whenever theinstrument has undergone a major change (i.e., replaceddetectors, increased sample size, switched column size, ordramatically modified run parameters).In order to determine the range of linearity it is necessary toconstruct response curves. These may be obtained by chargingvarying amounts of sample of each pure component to thechromatograph and then plotting all the response counts versusthe appropriate partial pressures. Tables II and III show therange of partial pressures used for the various components.NOTE 9--To generate pure component data necessary toconstruct linearity plots, it is suggested that mini-programs bewritten to run just long enough to charge the GC with thecomponent of interest, eIute it from the TCD, and return thesample value to the load position. This will avoid waiting for theinstrument to proceed through the complete cycle of 35 minutesbefore another data point can be determined.NOTE 8--A suggested manifold arrangement for enteringsamples to the chromatograph under vacuum is shown in Figure5.3.5 Vacuum Pump--Must have the capability of producinga vacuum of 1 mm of mercury absolute or less.NOTE lO--Dry air can be used for the calibration ofoxygen and nitrogen, using composition values of 21.87 mol %

for oxygen (includes argon which is eluted with oxygen on amolecular sieve column at these conditions) and 78.08 mol %for nitrogen.4Table IIRange of Partial Pressures Used to Determine Pure ComponentLinearity Response Data on Partition Column (Column 2) byThermal Conductivity DetectionPartial Pressure RangeComponent mm of MercuryNitrogen 50 - AtmosphereMethane 50 - AtmosphereCarbon Dioxide 50 - AtmosphereEthane 50 - AtmosphereHydrogen Sulfide* 50 - Atmosphere*CAUTION: Exercise appropriate handling procedures whenusing pure hydrogen sulfide. See Appendix B-3.Table IIIRange of Partial Pressures Used to Determine Pure ComponentLinearity Response Data on Adsorption Column (Column 1)by Thermal Conductivity DetectionPartial Pressure RangeComponent mm of MercuryOxygen 50 - AtmoshpereNitrogen 50 - AtmoshpereMethane 50 - AtmoshpereCarbon Monoxide 20 - 200Helium 20- 100NOTE 11--Procedures for the calibration and analysis ofhelium and carbon monoxide found by test to meet requirementsof this method are described in Appendix B.4.2 For each of the components nitrogen, methane, carbondioxide, ethane and hydrogen sulfide proceed as follows:4.2.1 Connect sample source to gas sampling part ofchromatograph. Evacuate manifold system, including sampleloop and check for leaks. (See Figure 5 for suggested manifoldarrangement.) Total system must be vacuum tight.4.2.2 Carefully open metering valve to admit purecomponent up to approximately 50 mm mercury absolute (2 in.Hg).4.2.3 Record exact partial pressure, operate appropriate gassample valve to place sample onto Column 2.4.2.4 Repeat steps 4.2.2 and 4.2.3 above at partial

pressures of 100, 200, 300, 400, 500, 600, 700 and atmosphericpressure in mm of mercury (4.0, 8.0, 12.0, 15.5, 19.5, 23.5, 27.5and atmospheric pressure in inches of Hg).4.3 For each of the compounds oxygen, nitrogen andmethane separated on the adsoption column (Column 1) proceedas follows:4.3.1 Connect sample source to gas sampling valve ofchromatograph. Evacuate manifold system, including sampleloop and check for leaks.4.3.2 Carefully open metering valve to admit purecomponent up to approximately 50 mm absolute (2 in. of Hg).TOVACUUMNEEDLE ~ PUMP• \ CA R R i E R.-.,'--._J'-~-~TO I GAS t COLUMNGAS CHROMATOGRAPHSAMPLE VALVEf VENTICYLINDERIIMANOMETERFigure 5 -Suggested Manifold Arrangement for EnteringVacuum Samples.4.3.3 Record exact partial pressure, operate appropriate gassample valve to place sample on Column 1.4.3.4 Repeat steps 4.3.2 and 4.3.3 above at partial pressuresof 100, 200, 300, 400, 500, 600, 700 and atmospheric pressure inmm of mercury absolute (4.0, 8.0, 12.0, 15.5, 19.5, 23.5, 27.5and atmospheric pressure in inches of Hg).NOTE 12--Dry air can be used for the calibration ofoxygen and nitrogen in lieu of the pure components due to thehazard of handling pure oxygen. The procedure for air is exactlythe same as for pure components (4.3) except that the partialpressure recorded for air is allocated proportionately21.87 mol % to oxygen and 78.08 mol % to nitrogen. Thus, airsampled at 100 mm mercury absolute yields a point for theoxygen curve at 21.9 mm of mercury absolute and a point on thenitrogen curve at 78.1 mm of mercury absolute. Thus, acomplete calibration curve using air to atmospheric pressureresults in a linearity curve for oxygen over the range 0 to 21.9mol % and a linearity curve for nitrogen over the range 0 to

78.1 mol %.4.4 From experimental data developed in accordance with4.2, 4.3, response curves shall be prepared in the followingmanner:4.4.1 Determine area counts of all peaks of interest.4.4.2 Tabulate peak area counts opposite the appropriatepartial pressure used for each calibration run.4.4.3 Plot the data in 4.4.2. Use rectangular coordinatepaper, the y-axis being partial pressure, the x-axis being peakarea counts. Draw smooth lines through the points plotted forpeak area count and extend down to zero. The linear range willbe that portion from zero to the point at which the plot departsfrom a straight line.5. CALIBRATION PROCEDURE5.1 The routine method of calibration is to use the responsefactor from a gas reference standard of known composition. Thismethod may be used for those components in an unknown thatlie within the proven linear range for a specific chromatographicinstrument.5.1.1 Connect reference standard gas to gas sampling partof chromatograph. Evacuate manifold system, including sampleloop and check for leaks.5.1.2 Carefully open metering valve to admit referencestandard gas up to pressure decided upon for all runs. (Seeanalytical procedure.)5.1.3 Record atmospheric pressure and start program toactuate sample valve to place sample on Column 2.5.1.4 Determine peak area counts from the TCD and FIDfor all components of interest. These data shall be used tocalculate response factors in accordance with section 7.6. ANALYTICAL PROCEDURE6.1 General--The full range analysis of a gaseous sample firstrequires a run on an adsorption column (Column 1) at isothermalconditions to determine oxygen, nitrogen and methane. It issuggested that a temperature of 60°C be used in conjunctionwith thermal conductivity detection for this section of theanalysis. In about three minutes, methane will have eluted fromside A of the TC cell and the program should rotate the eightport routing valve (V3) so causing Column 1 to be placed in theback flush mode. The remaining components will now exit fromthe system through side B. This now places Column 2 in serieswith side A of the TC cell. At the same time as valve (V3) isrotated, both V1 and V2 sampling valves should automatically

be moved to the sample "load" position. (A schematic flowdiagram of this procedure is shown in Figure 6.)Evacuate VI and V2 and then fill with fresh sample usingthe manifold arrangement shown in Figure 5. This part of theprocedure must be carried out in approximately four minuteswhich is the period of time needed to complete the back-flushingof Column 1. The program has now reached an elapsed time ofseven minutes. At this point V1 is rotated and a sample nowpasses into Column 2. Meanwhile the oven temperature stillMolecular Sieve ColumnTC-IsothermalTCD (Col. 1)OxygenNitrogenMethane ~- Briged in Mol %UCL-45 ColumnFID(Col. 3)Weight Percent --iso-Pentanen-Pentane2,2-Dimethylbutane2-Methylpentane2,3-Dimethylbutane3-MethylpentaneCyclopentanen-HexaneMethylcyclopentane2,2-Dimethylpentane2,4-Dimethylpentane2,2,3-TrimethylbutaneBenzene3,3-DimethylpentaneCyclohexane2-Methylhexane2,3-Dimethylpentane3-Methyihexane1,1 -Dimethylcyclopentanelt,3-Dimethylcyclopentanelc,3-Dimethylcyclopentanelt,2-Dimethylcyclopentane3-Ethylpantanen-HeptaneMethylcyclohexane

2,2-Dimethylhexane1,1,3-TrimethylcyclopentaneEthylcyclopentane2,4-Dimethylhexane2,5-Dimethylhexane1 c,2t,4-Tdmethylcyc[opentaneI c,2t,3-Tdmethylcyclopentane2,3,4-TrimethylpentaneToluene2,3-DimethylhexaneSilicone Comeosite ColumnTC/FID Split EffluentPart isothermal - part temperature programmedTCD (Col. 2)Nitrogen (Air Free)MethaneCarbon DioxideHydrogen Sulfide~-- Briged in Mol % ~----) Bdged in Weight %UCL-45 ColumnFID (Col. 3)Weight Percent --FID (CoL 2)MethaneEthanePropaneiso-Butanen-Butaneiso-Pentanen-PentaneIn Weight Percent-- Converted toMol Relationship2-Methylheptane4-Methylheptane3-Methylheptane3,4-Dimethylhexanelc,2c,4-Trimethylcyclopentanelc,3-Dimethylcyclohexanelt,4-Dimethylcyclohexane1,1 -Dimethylcyclohexane1-Methyl-cis-3-ethylcyclopentane

1-Methyl-trans-2-ethylcyclopentane1-Methyl-l-ethylcyclopentanen-Octanelt,2-Dimethylcyclohexanelc,2c,3-Tdmethylcyclopentane1 c,2-Dimethylcyclohexane2,5-Dimethylheptane3,5-DimethylheptaneEthylbenzene1,3-Dimethylbenzene1,4-Dimethylbenzene2,3-Dimethylheptane3,4-Dimethylheptane2-Methyloctane3-Methyloctane1,2-Dimethylbenzenen-NonaneDecanesUndecanesDodecanesTridecanesTetradecanesFigure 6 - Calculation Procedure.NOTE 13mBridge FID (Col. 3) in weight % to FID (Col. 2). Convert both data columns to moles and then bridge to TCD (Col.2 &l). (See 7.2)6remains at 60°C isothermal. Components leave Column 2 in thefollowing order - inerts, methane, carbon dioxide, ethane andhydrogen sulfide, as shown in Figure 3, and pass through theeffluent splitter. Suggested split ratio is one part to the hydrogenflame detector, three parts to the thermal conductivity detector.At an elapsed time of 11 minutes, or after four minutes inColumn 2, V2 is automatically rotated and a sample is chargedto Column 3 that separates the components iso-pentane throughtetra-decanes. At 14 minutes elapsed time the hydrogen sulfidewill have cleared the TC cell and been integrated, and the TCdetection part of the analysis is completed.At this time the oven temperature heating programcommences and adds heat at approximately 20°C per minute,reaching the final temperature of 170°C at approximately 20minutes elapsed time. Meanwhile, Column 3 is analyzing theheavy ends of the sample and detecting components on the

second hydrogen flame detector (FID 2) and yielding achromatogram as shown in Figure 4. At 23 minutes elapsed timethe propane, iso- and normal butanes and iso- and normalpentanes have eluted from Column 2 and have been detected onFID 1 (Figure 3). At this point the program causes V3 to rotateso back-flushing the hexanes plus to the atmosphere via'the TCceil, and also returns both V1 and V2 to the sample "load"position. After two more minutes (25 minutes elapsed time)tetradecane has cleared FID 2 and the oven is switched to the"cool down" mode. Ten more minutes (35 minutes of elapsedtime) and the system is now equilibriated at 60°C, all valves areback to the starting position of the cycle and a new sample maybe charged to the system.Response factors from natural gas reference standards usedin conjunction with response curves derived from purecomponents as discussed in Sections 4 and 5 of this method areessential to accurately determine the composition of an unknowngas sample. Care must be maintained to ensure that identicalinstrument operating conditions exist during the running of thegas standard and the unknown. As long as this stipulation is metnumerous samples can be analyzed using a single gas referencestandard run. If the sample volumes are measured at atmosphericpressure the operator is at the mercy of the day-to-day variationsin barometric pressure resulting in poor, unnormalized totals(see Note 15-Calculations). It is suggested that the operatoralways charge a consistent partial pressure of 400 mm pressureto the sample loop using the manifold arrangement discussedearlier-Figure 5. This procedure will remove the effect offluctuating barometric pressure and make sure that the GCreceives a representative sample, particularly when the gas isrich in heavy ends and has been sampled from a hightemperature source. If a component concentration falls outsidethe established linear range of that component, reduce thesample volume so that all components stay in the linear range.One response factor can then be used for all concentrations ofthat component.6.2 Preparation and Introduction of Sample-If field dataindicate the gas sample was taken at a temperature greater thanthat of the laboratory, the sample must be heated to at least 20°Fabove the sampling temperature. It is recommended that all linesconnecting the sample to the GC be made of stainless steel andthat these lines should be permanently heated to a temperaturehigher than any expected sampling temperature. This includes

any gas filter that may be in use in the charging line to the GCand also any tubing and connections that may be inside thechromatograph but not inside the oven. The purpose of this is toensure that the gas shall not be allowed to drop below its dewpoint and shall be representative of the gas that was sampled.NOTE 14--To be sure of representative samples in thefield, select appropriate sampling method from GPA Publication2166.Table IVExample of Response Factors Determined from ReferenceStandard and Pure Components by Thermal ConductivityComponent Mol % Response Factor2.73 = 0.0001534Oxygen 17795Nitrogen .29.282 = 0.0001158252925Methane (Mol Sieve) 69.97 = 0.0001405498116Methane (Silicone Composite) 52.42 = 0.000039191337500Carbon Dioxide 7.37 = 0.00002630280215Hydrogen Sulfide 2.5 = 0.00002857875006.2.1 Evacuate charging system, including sample loop,back to the valve on sample cylinder to 1 mm of mercuryabsolute or less. Close valve to vacuum source and carefullymeter gas from sample cylinder into charging system untilsample loop is filled at the selected pressure as indicated on themanometer. The chromatograph is now ready to start theanalysis procedure outlined in Section 6.1.7. CALCULATIONS7.1 Response factors are calculated for each componentfrom nitrogen through normal pentane using the peak areacounts of the reference standard. The appropriate mol or weightpercent of each component is used depending upon whether thepeak is taken from the TC cell or the FID. (Examples are shownin Tables IV and V.) The response factors are calculated by thefollowing formula:Table VExample of Response Factors Determined from ReferenceStandard by FIDComponent Weight % Response Factor

Methane 47.69 = 0.000006886926850Ethane 11.89 = 0.000007121670658Propane 151417.3523 6 = 0.00000732Iso-Butana 7.46 = 0.00000810919943n-Butane 7.28 = 0.00000806902966iso-Pentane 3.04 = 0.00000893340424n-eentane 3.06 = 0.00000899340528Where K = M (or W)PK - Response factor on either tool or weight basisM - Mol percent of component in reference standardW - Weight percent of component in reference standardP - Integrator area counts of component in referencestandardNOTE 15--Some integrators determine a response factorK- PM (or W)Be sure to use the approach that is consistent with yourintegration equipment.7.2 Response factors for a flame ionization detector fromC 5 to C n can be determined relative to the response of pentaneby analyzing a liquid blend of aliphatic, aromatic, andnaphthenic hydrocarbons from C 5 to C n. (Examples of relativesensitivity values for the FID are shown in Table VI.) Weightsensitivities relative to i-C 5 and n-C 5 for the above componentsare very close to 1.00 so making peak area percent almost equalto weight percent. 1 Each area count is divided by the relativesensitivity for that particular component to convert to the trueweight distribution in counts. This distribution is then connectedto the C 1 through C 5 unnormalized weight percent distributionby the bridge components iC 5 and nC 5 and an unnormalizedweight percent for the components C 6 to C n may then becalculated. Both of these parts of the analysis may then be

converted to a mole relationship by dividing by the molecularweight. The non-hydrocarbons oxygen, nitrogen, carbon dioxideand hydrogen sulfide which have been analyzed on the TC sideof the system are then added to the rest of the analysis using thebridge component methane. (See Figure 6.) The unnormalizedtotal of all the components analyzed should be within +1.0% of100.00%. Any air is now removed from the analysis based onthe oxygen percent and the results may be normalized to an airfree basis. (See Table VII.)7.2.1 Response factors for the liquid blend C 5 to C n arecalculated by the following formula:K- WPWhereK - Weight response factorW -Weight percent of component in liquid blendP - Peak area counts of component in liquid blend7.2.2 Calculate the weight concentration of all thecomponents in unknown determined by FID in 7.1 and 7.2 bythe following formula:W=PxKWhereW - Weight percent of component in unknownP - Peak area counts of component in unknownK - Weight response factor as determined in 7.1 or 7.2. I7.2.3 Calculate the tool % of oxygen, nitrogen, methane,carbon dioxide and hydrogen sulfide in unknown as determined8by TC from the following formula:M=PxKWhereM -Mol percent of component in unknownP -Peak area counts of each component in unknownK - Molar response factor as determined in 7.1Table VIExample of Relative Sensitivity Values Determined from LiquidBlend by Flame Ionization Detector(as Described in 7.2)Component Relative Sensitivityiso-Pentane 1.00

n-Pentane 1.002,2-Dimethyibutane 0.992-Methylpentane 0.992,3-Dimethylbutane 0.983-Methylpentane 0.98Cyclopentane 0.98n-Hexane 0.99Methylcyclopentane 0.972,2-Dimethylpentane 0.982,4-Dimethylpentane 0.982,2,S-Trimet hylbutane 0.98Benzene 1.07S,3-Dimethylpentane 0.96Cyclohexane 0.972-Methylhexane 0.962,3-Dimethylpentane 0.963-Methylhexane 0.961,1-Dimethylcyclopentane 0.97lt,S-Dimethylcyctopentane 0.971 c,3-Dimethylcyclopentane 0.97lt,2-Dimethylcyclopentane 0.973-Ethylpentane 0.96n-Heptane 0.96Methylcyclohexane 0.972,2-Dimethylhexane 0.931,1,3-Trimet hylcyclop ent ane 0.94Ethylcyclopentane 0.972,4-Dimethylhexane 0.932,5-Dimethylhexane 0.931 c,2t,4-Trimethylcyclopentane 0.971 c,2t,3-Tdmethylcyclopentane 0.972,8,4-Trimethylpentane 0.93Toluene 1.022,3-Dimethylhexane 0.932-Methylheptane 0.934-Methylheptane 0.933-Methylheptane 0.933,4-Dimethylhexane 0.93I c,2c,4-Trimethylcyclopent ane 0.971 c,3-Dimethylcyclohexane 0.97lt,4-Dimethylcyclohexane 0.971,1 -Dimethylcyclohexane 0.971 -Methyl-cis-3-ethylcyclopentane 0.97

1 -Methyl-trans-2-ethylcyclopentane 0.971 -Methyl-1 -ethylcyclopentane 0.97n-Octane 0.93lt,2-Dimethylcyclohexane 0.971 c,2c,3-Trimethylcyclopentane 0.971 c,2-Dimet hylcyclohexane 0.972,5-Dimethylheptane 0.933,5-Dimethylheptane 0.93Ethylbenzene 0.991,3-Dimethylbenzene 0.981,4-Dimethylbenzene 0.982,3-Dimethylheptane 0.943,4-Dimethylheptane 0.942-Methyloctane 0.943-Methyloctane 0.941,2-Dimethylbenzene 0.98n-Nonane 0.94Decanes 0.95Undecanes 0.94Dodecanes 0.95Tridecanes 0.95Tetradecanes 0.95NOTE 16--Each area count is divided by the relativesensitivity value to get the true area count. 1Table VIICalculation of Unknown Sample using Response FactorsAdsorption Column - Thermal Conductivity DetectionAir ContainingResponse UnnormalizedComponent Counts Factor Mol %Oxygen 210 0.0001534 0.032Nitrogen 237928 0.0001158 27.545Methane 378759 0.0001405 53.2153omposite Silicone Column - Thermal Conductivity DetectionResponse UnnormalizedComponent Counts Factor Mol %Methane 1351682 0.00003919 52.972Carbon Dioxide 240863 0.00002630 6.335Hydrogen Sulfide 98732 0.00002857 2.821Composite Silicone Column - Flame Ionization DetectionResponse UnnormalizedComponent Counts Factor Weight % Mol Wt.Methane 5322628 0.00000688 36.620* 16.04

Ethane 849288 0.00000712 6.047" 30.07Propane 596340 0.00000732 4.365* 44.09iso-Butane 228233 0.00000810 1.849" 58.12n-Butane 286869 0.00000806 2.312" 58.12iso-Pentane 135164 0.00000893 1.207" 72.15n-Pentane 104274 0.00000899 0.937* 7215Silicone UCL-45 Column - Flame Ionization DetectionMoles2.283040.201100.099000.031810.039780.016730.01299Relative Corrected UnnormalizedComponent Counts Sensitivity Counts Weight % Mol Wt. Molesiso-Pentane 332181 1.00 332181 1.207n-Pentane 268065 1.00 268065 0.9372,2-Dimethylbutane 18200 0.99 18384 0.066* 86.18 0.000772-Methylpentane 93830 0.99 94778 0.339* 86.18 0.003932,3-Dimethylbutane3-Methylpentane 64900 0.98 66224 0.237* 78.16 0.00303CyclopentaneN-Hexane 145200 0.99 146667 0.524* 86.18 0.00608Methylcyclopentane2,2-Dimethylpentane 33916 0.98 34608 0.124" 85.76 0.001452,4-Dimethylpentane2,2,3-TrimethylbutaneBenzene 20550 1.06 19387 0.069* 80.31 0.000863,3-DimethylpentaneCyclohexane 11352 0.97 11703 0.042* 84.16 0.000502-Methylhexane 16190 0.96 16865 0.060* 100.20 0.000602,3-Dimethylpentane3-Methylhexane 8250 0.96 8594 0.031 * 99.76 0.000311,1 -Dimethyicyclopentanelt,3-Dimethylcyclopentanelc,3-Dimethylcyclopentane 15110 0.97 15577 0.056* 98.19 0.00057lt,2-Dimethylcyciopentane3-Ethylpentanen-Heptane 101176 0.96 105392 0.376* 100.20 0.00375Methylcyciohexane2,2-Dimethylhexane 21448 0.96 22342 0.080* 99.78 0.00080

1,1,3-TrimethylcyclopentaneEthylcyclopentane2,4-Dimethylhexane 7982 0.94 8492 0.030" 110.22 0.000272,5-Dimethylhexanelc,2t,4-Trimethylcyclopentane 4940 0.97 5093 0.018" 112.22 0.00016Air Containing Air Free Air FreeCorrected Mol % Corrected Mol % Mol %(Unnormalized) (Unnormalized) (Normalized)0.03227.545 27.429 27.43553.215 53.215 53.225Air Containing Air Free Air FreeCorrected Mol % Corrected Mol % Mol %(Unnormalized) (Unnormalized) (Normalized)53.215 53.2156.364 6.364 6.3652.834 2.834 2.835Air ContainingCorrected Mol %(Unnormalized)Air Free Air FreeCorrected Mol % Mol %(Unnormalized) (Normalized)53.215 53.2154.687 4.687 4.6882.308 2.308 2.3090.742 0.742 0.7420.927 0.927 0.9270.390 0.390 0.3900.303 0.303 0.303Air Containing Air Free Air FreeCorrected Mol % Corrected Mol % Mol %(Unnormalized) (Unnormalized) (Normalized)0.018 0.018 0.0180.092 0.092 0.0920.071 0.071 0.0710.142 0.142 0.1420.034 0.034 0.0340.020 0.020 0.0200.012 0.012 0.0120.014 0.014 0.0140.007 0.007 0.007

0.013 0.013 0.0130.087 0.087 0.0870.019 0.019 0.0190.006 0.006 0.0060.004 0.004 0.004Table VII - ContinuedSilicone UCL-45 Column - Flame Ionization DetectionAir Containing Air Free Air FreeRelative Corrected Unnormalized Corrected Mol % Corrected Mol % Mol %Component Counts Sensitivity Counts Weight % Mol Wt. Moles (Unnormalized) (Unnormalized) (Normalized)lc,2t,3-Trimethylcyclopentane 5420 0.97 5588 0.020" 113.22 0.00018 0.004 0.004 0.0042,3,4-TrimethylpentaneToluene 34318 1.02 33645 0.120" 92.13 0.00130 0.030 0.030 0.0302,3-Dimethylhexane2-Methylheptane 15722 0.93 16905 0.060* 114.23 0.00053 0.012 0.012 0.0124-Methylheptane3-Methylheptane3,4-Dimethylhexane 5249 0.93 5644 0.020* 114.23 0.00018 0.004 0.004 0.0041 c,2c,4-Trimethylcyclopentan elc,3-Dimethylcyclohexane 10651 0.97 10980 0.039* 112.21 0.00035 0.008 0.008 0.008lt,4--Dimethylcyclohexane1-1-Dimethylcyclohexane1-Methyl-cis-3-ethylcyclopentane1-MethyI-Trans-2-ethylcyclopentane 2252 0.97 2322 0.008* 112.21 0.00007 0.002 0.002 0.0021-Methyl-1 -ethylcyclopentanen-Octanelt,2-Dimethylcyclohexane 43566 0.93 46845 0.167* 114.23 0.00146 0.034 0.034 0.034lc,2c,3-Trimethylcyclopentane 1453 0.97 1498 0.005* 112.21 0.00005 0.001 0.001 0.001lc,2-Dimethylcyclohexane 2251 0.97 2321 0.008* 112.21 0.00007 0.002 0.002 0.0022,5-Dimethylheptane 10519 0.93 11311 0.040* 128.25 0.00031 0.007 0.007 0.0073,5-DimethylheptaneEthylbenzene

1,3-Dimethylbenzene1,4-Dimethylbenzene 35740 0.96 37229 0.133" 117.23 0.00114 0.027 0.027 0.0272,3-Dimethylheptane3,4-Dimethylheptane2-Methyloctane 15482 0.94 16470 0.059* 128.25 0.00046 0.011 0.011 0.0113-Methyioctane1,2-Dimethylbenzene 10251 0.98 10460 0.037* 106.16 0.00035 0.008 0.008 0.008n-Nonane 30120 0.94 32043 0.115" 128.25 0.00090 0.021 0.021 0.021Decanes 63980 0.95 67347 0.241 * 142.28 0.00169 0.039 0.039 0.039Undecanes plus 56871 0.94 60501 0.216" 156.30 0.00138 0.032 0.032 0.032100.128* 99.980 100.000*NOTE 17--1fall components are measured, the unnormalized total should not vary more than + 1.O0% from 100.00%.APPENDIX ASupplementary ProceduresA. 1 Extended Analysis by Capillary Gas ChromatographyA. 1.1 Scope-This method covers the determination of thechemical composition of natural gas by combining the analysisdescribed in GPA Standard 2261 with an extended analysis ofthe hexanes and heavier components using capillary gaschromatography. Table A-I and Table A-II name the individualor grouping of components for GPA Standard 2261 andExtended Analysis respectively.A.1.2 Summary of Method-An analysis of a gaseousmixture is made according to GPA Standard 2261 except resultsare reported to three places to the right of the decimal for moreaccurate normalization of the combined data. On the samegaseous mixture, an analysis is made on the iso-pentane andheavier fraction by capillary gas chromatography. The latteranalysis provides essentially an individual component characterizationof this fraction as shown in Figure A-I. Forconvenience of calculation, some peak groupings are madeaccording to hydrocarbon type to produce Table A-II forcalculating the physical properties of gaseous mixtures.Table A-IGPA Standard 2261

1. Hexanes and heavier2. Nitrogen3. Methane4. Carbon Dioxide5. Ethane6. Propane7. Iso-butane8. n-Butane9. leo-pentane10. n-PentaneThe two analyses are combined into a simple report usingthe common peaks iso-pentane and normal pentane in eachanalysis as the bridge to correctly adjust the peak areas of the10components shown in Table A-II to the same sample size as thecomponents of Table A-I. The peak areas of Table A-II are thenconverted to molar response using response factors (if needed)and molecular weight factors relative to pentane. Theseconverted areas are calculated to mol percent relative to the totalmol percent of pentanes determined by GPA Standard 2261.Peaks 2 through 10 in Table A-I are summed with peaks 11through 33 in Table A-II and normalized to 100.000%.Table A-IICapillary Extended Analysis9. Iso-pentane10. n-Pentane11. Neohexane12. 2-Methylpentane13. 3-Methytpentane14. n-Hexane15. Methylcyclopentane16. Benzene17. Cyclohexane18. 2-Methyihexane19. 3-Methylhexane20. Dimethylcyclopentanes21. n-Heptane22. Methyicyclohexane23. Trimethylcyclopentanes24. Toluene25. 2-Methylheptane26. 3-Methylheptane27. Dimethylcyclohexanes

28. n-Octane29. C 8 Aromatics30. C 9 Naphthenes31. C 9 Paraffins32. n-Nonane33. Decanes and heavierA.2 ApparatusA.2.1 Apparatus description includes only that additionalapparatus required for a capillary gas chromatography system.Reference should be made to GPA Standard 2261 forinformation on apparatus requirements.A.2.2 Chromatograph-The chromatograph must be equippedwith flame ionization detector, temperature programmingthat includes settable initial and final constant temperatureperiods, and settable temperature programming rates over therange of 2 - 10°C per minute; inlet splitter in heated zone; smallvolume capillary connectors at inlet splitter and detector inlet toallow proper location of capillary column ends in inlet splitterand detector inlet, and provision for makeup gas at detector inletif detector manifold design requires such gas.A.2.3 Sample Inlet System-A gas sampling valve must beprovided to introduce about 2 cc of sample gas into the inletsplitter. The gas sampling valve should be mounted in its owntemperature controlled oven capable of being maintained at 20-50°F above the highest expected field sampling temperature.NOTE A-1--A vacuum sample entry system, such asdescribed in GPA Standard 2261, can be used to avoid heatingthe sample valve. For example, a 5 cc sample loop filled to 300mm partial pressure would provide the approximate 2 cc of gasfor analysis. The 300 mm partial pressure would greatly reducethe possibility of condensation of heavier sample components.A.2.4 Capillary Column-A 60 meter x 0.26 mm ID fusedsilica capillary coated with a 1.0 micron film thickness of DB-1has been found by experiment to be suitable for this analysis.A.2.5 Integrator/computer-Wide range, 0-1 V/0-10 V, withboth printing and plotting capabilities, baseline tracking, andtangent skim peak detection.A.2.6 Carrier Gas-The sensitive flame ionization detectorrequires hydrocarbon free carrier gas. Chromatographic gradehelium (99.998% pure) has proven satisfactory for this analysis.A.2.7 Pressure Reducing and Flow ControlDevices-Upstream restrictions such as flow controllers are notpermitted when using inlet sample splitters. Column inlet

pressures should remain constant during splitting and the periodof analysis.A.3 Preliminary PreparationsA.3.1 Hydrocarbon Test Blend-Prepare a gravimetric standardof n-hexane, n-octane, n-decane and n-dodecane using>98% purity of the pure hydrocarbons. Weigh accuratelyapproximately 1 gram of each hydrocarbon into a narrow mouth4 ounce bottle followed by approximately 96 grams of hexanefreen-pentane. Cap the bottle tight and keep refrigerated exceptduring use. From the recorded weights calculate the exactconcentration of the hydrocarbons in the blend.A.3.2 Instrument Conditions-The capillary instrumentshould be installed according to the manufacturer's instructions,including installation of the capillary column and inlet splittersystem. Parameters to be recorded for the operation file include:Hydrogen Press., psigAir Press., psigCarrier Gas Press., psigInitial TemperatureTemperature ProgramFinal HoldInlet Splitter Temp.Detector TemperatureSplit Ratio(15-30) (Nominal Range)(40-60) (Nominal Range)(40-60) (Nominal Range)30°C for 3.0 rain.6°C/rain. for 20.0 min.150°C for 1 min.175°C175°C1:400 (nominal)NOTE A-2--Before the capillary column is inserted into thedetector inlet, the carrier gas flow through this column shouldbe measured at 30°C, using a soap bubble meter or similartechnique to measure flow as a function of time. At 30°C,establish a flow of 1.8-2.0 cc/minute by adjusting the columninlet pressure up or down until the desired flow rate is achieved.A.3.3 Setting Split Ratio-Connect a reference gas to thesample inlet system and with splitter set near 1:200, inject a 2 ccsample of gas and record the iso- and normal pentane peaks onscale. Repeat the above step at a ratio of 1:300, record the

pentane peaks and observe whether the resolution has improved.Repeat this step and increase the split ratios until no visualresolution differences are observed for these two peaks. Selectthe smallest split ratio that exhibits the best resolution for thisoperating parameter.11A.3.4 Sample Discrimination Check-Using a microlitersyringe, inject 1.0 microliter of the blend prepared in A.3.1,using the split ratio parameter determined in A.3.3 and thetemperature program parameters detailed in A.3.2. Record thepeak retention times and peak areas. For the blend componentsused, the flame ionization detector responds relative to mass(weight), therefore since the same mass of each of the fourcomponents was injected, the area under the individual peaksshould be very close to the same value. If not, adjust inlet splittertemperature upward and repeat test until the four peak areasagree to within +1% relative.NOTE A-3--This blend can be used for guidance inadjusting instrument parameters for optimum analysis time sincen-decane is usually the last significant component in naturalgas.A.4 Analysis ProcedureA.4.1 Make an analysis on the unknown gas according toGPA Standard 2261. If this analysis is made at 120°C or above,record the unnormalized mol percent values for nitrogen throughn-butane, the peak areas and unnormalized tool percent for isoandnormal pentane, and the peak area for hexanes and heavier.For an analysis made below 120°C, do not record the peak areafor hexanes and heavier.NOTE A-4--At temperatures above 120°C, the GPAStandard 2261 is expected to measure all of the hexanes andheavier components. This may not be the case for lower columntemperatures.A.4.2 Connect the unknown gas to the sample inlet systemof the capillary gas chromatograph and inject about 2 cc of gas.Record the peak areas, beginning with iso- and normal pentane,of the heavier peaks in the sample. A typical chromatogram of acapillary column separation is shown in Figure A-I.A.5 CalculationsA.5.1 Assemble Peak Areas for Table A-II by appropriatelygrouping like hydrocarbon types of the same molecular weightinto a single area for inclusion in Table A-II. Figure A-I hasevery peak labeled with its corresponding location in Table A-II.

A.5.2 GPA Standard 2261 above 120 ° C-Areas in Table AIIheavier than n-pentane are normalized to 100%. The normalizedarea percent of each Table A-II component is multiplied bythe total area of hexanes and heavier from GPA Standard 2261(Table A-I). This correctly distributes the total hexanes andheavier area of GPA Standard 2261 (Table A-I) according to thecomponents named in Table A-II. Next the areas in Table A-IIare calculated to tool percent as follows:Cn = (Ac x Ms x Rn)(As x Mc) x CsWhereCn = Mol percent of component nAc = Peak area of component nAs = Peak area of iso- and normal pentaneCs = Mol percent of iso- and normal pentaneMc = Molecular weight of component nMs = Molecular weight of iso- and normal pentaneRn = Flame ionization response factor for component n (ifneeded)NOTE A-5--Flame ionization response factors are significantfor benzene and toluene. These are also significant componentsin natural gas residues. For this method the response factor(multiplying factor)for benzene is assumed to be 0.928 and fortoluene 0.972. All remaining components in Table A-I haveassumed response factors relative to iso-and normal pentanehaving response factors of 1.000. (Refer to Table V1, main text.)W i\\\\Time - MinutesFigure A-I - Natural Gas Residue by Capillary Gas Chromatography.42Table A-IIIExample Calculations (above 120°C)TABLE A-IArea Unnorm. Norm.Mol % Mol %1. 4400 4.031 4.0122. 71.456 71.1293. 1.062 1.0574. 9.843 9.7975. 5.462 5.4376. 2.998 2.984

7. 3.014 3.0008. 1.012 1.0079. 5500 .921 .91710. 5000TABLE A-IIArea Norm. x Area (1) Apportioned C nArea % Area (1)9.10.11. 600 .397 4400 17.468 .003 .00312. 18500 12.229 538.076 .083 .08313. 14250 9.419 414.436 .064 .06414. 21350 14.113 620.972 .096 .09615. 15600 10.312 453.728 .072 .07216. 9500 6.280 276.320 .042 .04217. 17890 11.826 520.344 .082 .08218. 6500 4.297 189.068 .025 .02519. 6450 4.263 187.572 .025 .02520. 7540 4.984 219.296 .029 .02921. 11840 7.826 344.344 .045 .04522. 10560 6.980 307.120 .041 .04123. 1200 .793 34.892 .004 .00424. 4560 3.014 132.616 .018 .01825. 1100 .727 31.988 .004 .00426. 905 .598 26.3t6 .003 .00327. 1360 .899 39.556 .005 .00528. 826 .546 24.024 .003 .00329. 425 .281 12.364 .001 .00130. 100 .066 2.904 <.001 <.00131. 100 .066 2.904 <.001 <.00132. 75 .049 2.156 <.001 <.00133. 50 .033 1.452 <.001 <.001151281 100.000 4400.000 100.450 100.000TABLE A-IArea1.2.3.4.5.6.7.8.

9. 550010. 5000TABLE A-IIAreaTable A-IVExample Calculations (below 120°C)Unnorm.Mol %4.03171.4561.0629.8435.4622.9983.0141.012.921Norm.Mol %4.01271.1291.0579.7975.4372.9843.0001.007.917x A-I (9)(10) Adjusted forA-II (9)(10) Sample SizeO n9. 18670010. 16790011. 600 .02961 17.766 .003 .00312. 18500 547°786 .084 .08413. 14250 421.942 .065 .06514. 21350 632.174 .097 .09715. 15600 461.816 .073 .07316. 9500 281.295 .043 .04317. 17890 529.723 .084 .08418. 6500 192.465 .025 .02519. 6450 190.984 .025 .02520. 7540 223.259 .030 .030

21. 11840 350.582 .047 .04722. 10560 312.682 .042 .04223. 1200 35.532 .004 .00424. 4560 135.022 .018 .01825. 1100 32.571 .004 .00426. 905 26.970 .003 .00327. 1360 40.269 .005 .00528. 826 24.458 .003 .00329. 425 12.584 .001 .00130. 100 2.961 <.001 <.00131. 100 2.961 <.001 <.00132. 75 2.221 <.001 <.00133. 50 1.480 <.001 <.001151281 4479.502 100.456 100.000A.5.3 The mol percent from the individual componentsfrom A.5.2 are summed with the n-pentane and lightercomponents from GPA Standard 2261 (Table A-I) andnormalized to 100.000%. An example calculation is shown inTable A-III.A.5.4 GPA Standard 2261 below 120°C - The summedareas of iso and normal pentane in Table A-II are dividedinto the summed areas of iso and normal pentane of Table A-Ito produce a multiplying factor to convert the componentareas of Table A-II to the same sample size as used in GPAStandard 2261 (Table A-I). These adjusted areas are calcula-tedto mol % in exactly the same manner as described in A.5.2.These tool % data are summed into the n-pentane and lighterdata from GPA Standard 2261 and the combined data isnormalized to 100.000%. An example calculation is shown inTable A-IV.APPENDIX BB.1 Determination of Carbon Monoxide-This component isencountered in association with oxygen, nitrogen, carbondioxide and the conventional hydrocarbons in the effluentstreams from combustion processes such as insitu combustion,manufactured gas, and many varied types of stack gas. A 10 ft.molecular sieve 5A column, 100/120 mesh substituted for theadsorption column shown in 3.1.3 of the main text, willdetermine carbon monoxide since it elutes shortly after methane.If a calibration gas is available containing carbon monoxide,obtain a response factor as for methane on the molecular sievecolumn. However, should a gas blend not be available, acalibration curve should be developed using pure carbon

monoxide to determine the extent of the nonlinearity, if present.B.2 Determination of Hydrogen and Helium-If hydrogen is tobe separated from helium, a 40 ft. molecular sieve 13X column1330# nitrogen carrier40°C even1/2 cc. loop250 m.a.40-foot tool sieve 13X(1/8- inch col.)Thermal conductivity detectionE-r-,o,-r-I I I I0 1 2 3 4Time, minutesFigure B-1-Separation of Helium and Hydrogen.using nitrogen or argon as a carrier gas may be used (FigureB-1). Low temperature, 40°C or less, is necessary to effect thisseparation.When helium is used as a carrier gas and hydrogen ispresent, hydrogen will elute on the standard molecular sievecolumn just before oxygen. It will also be noted that a lowpercentage recovery is obtained in the case where helium ispresent in the unknown gas indicating the nee.d for a separatehelium determination on the long 40 ft. (12 meters) molecularsieve 13X column. If a calibration gas blend is availablecontaining hydrogen and helium, it should be used to obtainresponse factors. However, this not being the case, the purecomponents, hydrogen and helium, may be used to developresponse curves in the manner set forth in section 4.3, main text.B.3 Determination of Hydrogen SulfideAs indicated earlier in this text, to determine the hydrogensulfide content of a gas accurately, analyses should be made atthe sample source. However, in the case where a field analysishas not been made and although corrosion of the sample bottlemay have resulted in some loss of hydrogen sulfide, an analysisof the in-place component may be made by gas chromatography.It is necessary to charge a sample of pure hydrogen sulfide to thecolumn prior to charging the unknown gas. As soon as the purehydrogen sulfide has cleared the column, the unknown gas

should be charged. (All calibrations should be done the sameway, that is, each partial pressure charge of pure hydrogensulfide must be preceded by a full sample loop of pure hydrogensulfide.)The Maximum Allowable Concentration to which a personmay be exposed without approved respiratory protectionequipment is 10 ppm for an eight hour working period.Concentrations as low as 15.0 ppm may cause severe irritation tothe eyes and respiratory tract if the exposure lasts through theworking day. Exposure of 800 to 1,000 ppm may be fatal in afew minutes. The nose cannot be depended upon to detect thepressure of hydrogen sulfide, as 2- 15 minutes of exposure willcause the loss of sense of smell.APPENDIX CPreparation of EquipmentC.1 Linde Molecular Sieve Column--Clean a 12 ft. (3.6 meter)length of 1/8 in. (3.18 mm) stainless steel tubing with acetoneand dry with a stream of clean, dry air or inert gas. Plug one endof the tubing with about 1/2 in. of glass wool.Attach a small funnel to the other end and fill the tubingwith Type 13X, 100/120 mesh, dry Linde Molecular Sieve.Continuously vibrate the tubing while filling by moving anelectric vibrator up and down the length of the tubing. Whencompletely full, remove about 1/2 in. (10-15 mm) of the packingand replace with glass wool.Shape the finished column to mount conveniently in thechromatograph. Condition new column at 300°C overnight withcarrier flow and disconnected from TC cell.This column will separate hydrogen, oxygen, nitrogen andmethane. About 25 psig of carrier gas pressure at the inlet willgive a suitable flow rate.A column that has proved satisfactory for this type ofanalysis is the Silicone 200-500 column. It is most convenientsince this is the recommended column for analyzing thehydrocarbons in natural gas. Hydrogen sulfide elutes betweenethane and propane with good resolution. Extreme care must betaken when working with hydrogen sulfide due to the very toxicnature of the gas. The best ventilation possible must bemaintained in the laboratory.C.2 Silicone 200-500 Composite Column-A suitable partitioncolumn to resolve the components nitrogen and/or air, methaneand all hydrocarbons and non-hydrocarbons through normalpentane (as discussed in 3.1.4 and shown in Figure 3 main text)

can be made as follows:Clean a 20 ft., 2 ft., and 1 1/2 ft. (6, 0.6, and 0.4 meter)length of 1/8 in. (3.2 ram) stainless steel column tubing with14chloroethane followed by acetone, and then dry with a stream ofclean, dry air or inert gas. Bend into a U-shape for filling.Dilute 30 grams of Silicone 200-500 with about 300 gramsof ethyl ether in a filter flask and add 80 grams of 100/120 meshChromosorb P or equivalent support material. Shake the flaskgently to disperse the solvent. Connect a vacuum line to the flaskand evaporate the solvent. Swirl the flask gently several timeswhile removing the solvent, to avoid concentration of thesilicone in the upper layer.Pour the dry packing into both ends of the 20 ft. length oftubing using a small funnel and electric vibrator to completelyfill the column. Plug each end with 1/2 in. (10-15 mm) of glasswool.Shape the finished column to mount conveniently in thechromatograph.Pour some 80/100 mesh Chromosorb 102 into the 2 ft.length of tubing using a funnel and electric vibrator tocompletely fill the column. Plug each end with 1/2 in. (10-15mm) of glass wool.Repeat above procedure with Porapak T and the 1 1/2 ft.length of tubing.Using two 1/8 in. (3.2 mm) stainless steel unions join the2 ft. length of Chromosorb 102 and the 1 1/2 ft. length ofPorapak T to the 20 ft. length of Silicone 200-500 in that order.Condition column at 200°C (maximum) overnight before using.Caution: temperatures in excess of 200°C will harm this column.This column will separate air, methane, carbon dioxideethane, hydrogen sulfide, propane, iso-butane, n-butane, isopentane,n-pentane and other natural gas hydrocarbons asdescribed in the method procedure.C.3 UCL-45 Column-A suitable packed column to resolve thecomponents iso-pentane through tetradecane (as discussed in3.1.5 and shown in Figure 4 main text) can be made as follows:Clean a 15 ft. (4.5 m) length of 1/8 in. (3.2mm) stainlesssteel tubing (0.021 in. wall) with chloroethane followed byacetone, and then dry with a stream of clean, dry air or inert gas.Bend into a U-shape for filling.Weigh approximately 1.4 grams Silicone UCL-45 (methyl)

in a clean beaker and add 60 cc of chloroform. Allow severalhours for mixture to become completely homogeneous, stirringduring this time at regular intervals.Weigh 10.6 grams Gas Chrom QII or Supelcoport (100/120mesh) in a side-arm flask and add dissolved liquid phase. Withthe flask gently rotating pull a vacuum on the side-arm of flaskand apply mild heat. Continue until material is dry and can bepoured satisfactorily into a bottle. Place open bottle and materialin oven at 120°F for one hour. Pack column in U-shape using avibrator. Do not use a vacuum pump on the column during thepacking process. Plug each end with 1/2 in. (10-15 ram) glasswool, and bend finished column to required shape forinstallation in the chromatograph. Condition column at 200°Covernight with carrier gas flow before using.C.4 Preparation of a Reference Standard by Weight-Materialsrequired:a. Five gallon cylinder.b. 2,000 gram balance, sensitivity 10 mg.c. 100 ml pressure cylinder.d. Pure components, methane through n-pentane, andcarbon dioxide. All materials except methane, carbondioxide and possibly ethane, will be added as a liquid.The pure components should be 99+% pure. Run chromatogramon each component to check on given composition.Evacuate the five gallon cylinder for several hours. Evacuatethe 100 ml cylinder and obtain its true weight. Connect the 100ml cylinder to a source of pure n-pentane with a metalconnection of calculated length to contain approximately theamount of n-pentane to be added. Flush the connection with then-pentane by loosening the fitting at the 100 ml cylinder valve.Tighten the fitting. Close the n-pentane valve and open the 100ml cylinder valve to admit the n-pentane from the connectionand then close. Disconnect and weigh the 100 ml cylinder toobtain the weight of n-pentane added.Similarly, using connections of suitable length for eachcomponent, add iso-pentane, n-butane, iso-butane, propane,ethane and carbon dioxide as desired to include in the referencestandard. Weigh the 100 ml cylinder after each addition toobtain weight of component added.Connect the 100 ml cylinder to the five gallon cylinder usingas short a connection as possible. Open valves on both cylindersto transfer the sample. Disconnect and weigh the 100 mlcylinder to obtain weight of sample not transferred. Analyze the

material remaining in the 100 ml cylinder and calculate theweight of all components transferred into the five galloncylinder.Weigh a one quart cylinder containing pure methane atabout 1500 pounds pressure. Transfer the methane to the fivegallon cylinder until the pressure equalizes. Weigh the quartcylinder to determine the weight of methane transferred.Thoroughly mix the contents of the five gallon cylinder byheating at the bottom by convenient means such as hot water orheat lamp and leaving in vertical position for six hours or longer.From the weights and purities of all components added,calculate the composition and convert the weight percent to molpercent.NOTE C-I--Maintain the GPA Reference Standard at 21°Cor above, which is safely above the hydrocarbon dew point. If itshould be exposed to lower temperature, heat the bottom of thecylinder for several hours before using.REFERENCE1Dietz. W. A., J of GC, February, 1967, Pages 68-71.2 NIOSH No. MX1225000.15Appendix DCalculations Performed inAssociation with Gas AnalysesPREFACEAll physical constants used in these calculations should come from the most recent edition of GPA 2145. The constants usedin the examples that follow are from GPA 2145-95.The following physical constants not listed in GPA 2145 have been used in some of the calculations:0.25636 = vapor pressure of H20 (psia) @ 60°F (reference: U.S. Bureau of Standards)1230 = vapor pressure of CO 2 (psia) @ 100°F5000 = vapor pressure of N 2 (psia) @ 100°F= Gas Constant = 1545.3504 ft. - Ibf0b - mol °RCu.ft./lb - mol of any gas at 14.696 psia and 60°F - V _ RTn P(1545.3504)(459.67 + 60)(144)(14.696)= 379.48357Constant values for hexanes plus (C6+) or heptanes plus (C7+) if not actually determined by extended analysis should bemutually agreed upon by all concerned parties.

For ease of hand calculations in the examples shown the number of significant figures does not match those shown in GPA-2145. Precision of numbers in computer generated calculations should match that of GPA-2145. Rounding of numbers can causesome differences in final results. Computer generated calculations should only round those final numbers displayed on analyses,not numbers generated in intermediate calculations.For those calculations that are pressure dependent, the mathematics should be carried out using the constants at a pressure baseof 14.696 and the final result converted to the desired pressure base after all other mathematical functions are completed.Conversion of the physical constants to equivalent values at other pressure bases or the use of generated secondary factors prior toperforming calculations is not recommended.It is further recommended that computer software be written to follow these methods and recommendations and thathardbound documentation of the software programs be maintained and available at all times.For use in these calculations, mol fraction shall be equal to: mo1%/100.16Calculation of Physical Properties from Mol Fraction.D.1D.2Calculation of Heating Value (Btu), Relative Density (Specific Gravity) and Compressibility Factor (Z).The reader is referred to GPA 2172 for the proper method of calculation for these properties.Calculation of GPM (Liquid Volume Equivalent Expressed as Gallons per 1000 cu. ft. of Gas) of Natural Gas.ComponentColumn 1 Column 2 Column 3 Column 4Mol Fraction Cu. Ft./Gallon GPM @ 14.696 psia GPM @ 14.650 psia@ 14.696 psia (Col. 1 x 1000)/Co1.2 Col. 3 x 14.650GPA-2145 14.696Nitrogen 0.0068 91.413Methane 0.7987 59.135Carbon Dioxide 0.0056 58.807Ethane 0.1034 37.476 2.759 2.7504Propane 0.0523 36.375 1.438 1.4335Iso-Butane 0.0074 30.639 0.242 0.2412

N-Butane 0.0138 31.791 0.434 0.4326Iso-Pentane 0.0040 27.380 0.146 0.1455N-Pentane 0.0035 27.673 0.126 0.1256Hexanes Plus 0.0045 23.235* 0.194 0.1934Totals 1.0000 C2 + GPM = 5.339 5.3222C3 + GPM = 2.580 2.5718IC5 + GPM = 0.466 0.4645* Arbitrarily assumed value (used if average value not determined).Note: It is recommended that this calculation be carried out using cu.ft./gallon constants at a pressure base of 14.696 psia untilthe final calculation at which time GPM can be converted to any desired pressure base as shown. Conversion of ormanipulation of constants prior to performing the calculation is not recommended.D.3 Calculation of 26-70 Gasoline Content of Natural Gas.Column 1 Column 2 Column 3Mol Fraction Vapor Pressure Partial PressureComponent GPA-2145 Col. 1 x Col. 2Iso-Pentane 0.0040 20.450 0.0818N-Pentane 0.0035 15.580 0.0545Hexanes Plus 0.0045 3.683* 0.0166Total A = 0.0120 B = 0.1529Note:* Arbitrarily assumed value (used if average value not determined).The reader is directed tO the GPSA Engineering Data Book, Vol. I, Section 6 (Storage), Figure 6-4for conversion of ReidVapor Pressure to True Vapor Pressure.17Mol Fraction of NC 4 Required to Produce 26 PSI Gasoline:[(27.5 x A) - B ] - 24.22 = mol fraction of NC 4 required[(27.5 x 0.012) - 0.1529 ] - 24.22 = 0.0073Where: 27.524.22AB= True Vapor Pressure (psia) required to obtain an ASTM ReidVapor Pressure of 26 psi.= NC 4 Vapor Pressure (51.72) - required pressure (27.5)= Sum of mol fractions of C5 + components.= Sum of Partial Pressures of C5 + components.ComponentColumn 1 Column 2 Column 3Mol Fraction Cu. Ft./Gallon GPM @ 14.696 psia

Col. 1 x 1000GPA-2145 Col. 2N-Butane 0.0073 31.791 0.2296Iso-Pentane 0.0040 27.380 0.1461N-Penatane 0.0035 27.673 0.1265Hexanes Plus 0.0045 23.235* 0.1937Total 26 psi Reid V.P. Gasoline GPM = 0.6959* Arbitrarily assumed value (used if average value not determined).D.4 Calculation of 14 psi Reid Vapor Pressure Gasoline Content of Natural Gas.14 psi Reid Vapor Pressure Gasoline content is calculated in exactly the same manner as 26 psi Gasoline with thefollowing two changes:(1) 15.25 is used in place of 27.5 as the required True Vapor Pressure to obtain a correct reading of 14 psi Reid.(2) 36.47 is used in place of 24.22 as the difference between NC 4 True Vapor Pressure and required pressure.D.5 Calculation of Actual Btu (Based on Field Determined H20 Content) of Natural Gas.Actual Btu/cu. ft. = Dry Btu @ PB x rl _ Pound_______~s (21.0649 ca. ft./lb x 14.696/PB)]I_ 1000000 _1Where: PB = Pressure Base (psia) of Dry BtuPounds = Field determined H20 Content in pounds per MMcf21.0649 = 379.48357 (cu. ft. per mol t-I20 )18.015 (mol wt. H20 )18D.6. Calculation of Btu per pound of Natural Gas.D.6a Calculation of Weight Fraction.ComponentColumn 1 Column 2 Column 3 Column 4Mol Fraction Molecular Wt. Comp. Pounds Weight FractionGPA-2145 Col. 1 x Col. 2 Col. 3Sample Mol. Wt.Nitrogen 0.0068 28.013 0.1905 0.0091Methane 0.7987 16.043 12.8135 0.6144Carbon Dioxide 0.0056 44.010 0.2465 0.0118Ethane 0.1034 30.070 3.1092 0.1491Propane 0.0523 44.097 2.3063 0.1106Iso-Butane 0.0074 58.123 0.4301 0.0206N-Butane 0.0138 58.123 0.8021 0.0385Iso-Pentane 0.0040 72.150 0.2886 0.0138N-Pentane 0.0035 72.150 0.2525 0.0121

Hexanes Plus 0.0045 92.489* 0.4162 0.0200Totals 1.0000 Sample mol wt. = 20.8555 1.0000* Arbitrarily assumed value (used if average value not determined).D.6b Calculation of Btu/Ib.ComponentColumn 1 Column 2 Column 3Weight Fraction Btu/Ib. Mass Comp. Btu/lb.GPA-2145 Col. 1 x Col. 2NitrogenMethaneCarbon DioxideEthanePropaneIso-ButaneN-ButaneIso-PentaneN-PentaneHexanes PlusTotal0.0091 m 00.6144 23891 146790.0118 m 00.1491 22333 33300.1106 21653 23950.0206 21232 4370.0385 21300 8200.0138 21043 2900.0121 21085 2550.0200 20899* 4181.0000 Btu/Ib. mass = 22624Notes: 1.2.* Arbitrarily assumed value (used if average value not determined).Btu/lb. mass constants from GPA-2145 are fuel as ideal gas.Since mass is not pressure dependent the final sample Btu/lb. mass should not be adjusted for any pressure basecorrections.19D-7. Conversion of Known Btu Value to Btu Value at Different Condition.Btu Conversion FactorsConditions Required Btu Conditionsof 14.650 psia 14.696 psia 14.730 psia

Known Dry Sat Dry Sat Dry SatBtu Multiply By:14.735 psia 15.025 psiaDry Sat Dry Sat14.650 Dry 1.000 0.9825 1.0031 0.9856 1.0055 0.9880 1.0058 0.9883 1.0256 1.0081psia Sat 1.0178 1.0000 1.0210 1.0032 1.0234 1.0056 1.0237 1.0059 1.0439 1.026114.696 Dry 0.9969 0.9794 1.0000 0.9826 1.0023 0.9849 1.0027 0.9852 1.0224 1.0049psia Sat 1.0146 0.9968 1.0178 1.0000 1.0201 1.0024 1.0205 1.0027 1.0405 1.022814.730 Dry 0.9946 0.9772 0.9977 0.9803 1.0000 0.9826 1.0003 0.9829 1.0200 1.0026psia Sat 1.0122 0.9945 1.0154 0.9977 1.0177 1.0000 1.0181 1.0003 1.0381 1.020414.735 Dry 0.9942 0.9768 0.9974 0.9800 0.9997 0.9823 1.0000 0.9826 1.0197 1.0023psia Sat 1.0118 0.9941 1.0150 0.9973 1.0174 0.9997 1.0177 1.0000 1.0377 1.020015.025 Dry 0.9750 0.9580 0.9781 0.9610 0.9804 0.9633 0.9807 0.9636 1.0000 0.9829psia Sat 0.9920 0.9746 0.9951 0.9777 0.9974 0.9800 0.9977 0.9804 1.0174 1.0000Note: Sat (saturation) assumes that the gas contains all of the water vapor it can hold at 60°F and the indicated pressure base.Formulas Used to Derive Btu Conversion Factors1. Dry to Dry: PB Required x Known Dry BtuKnown Dry Btu PB2. Dry to Sat: PB Required - 0.25636 x Known Dry BtuKnown Dry Btu PB3. Sat to Dry: PB Required x Known Sat BtuKnown Sat Btu PB - 0.256364. Sat to Sat: PB Required - 0.25636 x Known Sat BtuKnown Sat Btu PB - 0.25636Where: PB = pressure base (psia)20000