BASIC pH Meter - California Polytechnic Statebio/ubl/equip_files/basicph.pdf · pH/mV Standardize...

Operation Manual300408.1 Rev. G

BASIC pH Meter

Denver Instrument Company

pH/mV Standardize Setup Enter

Denver Instrument

power refinput

FETATC

1. Connect powercable to meterpower jack andto AC powersource.

Denver Instrument

power refinput

FETATC

2. Connect a glass pH electrode to theinput and ATC connectors, or connectthe FET pH electrode to the FET con-nector.


rel mV pH

3. Press pH/mV until the dis-play indicates the appro-priate measurementmode (pH or mV/relativemV).

4. Standardize the meter using upto three buffers by immersingthe electrode in a buffer, stir-ring, then pressing Standardizeto enter each buffer.

Standardizing

BASIC pH Meter Quick Reference

5. The display shows the currentreading in pH, mV, or relativemV units.


6. Press Setup to review elec-trode calibration and to clearor select buffer sets.

%slope

ClearSet Buffers


Measuring

S

Table Of ContentsQuick Reference . . . . . . . . . . . . . . . . . . . . . . .Inside Front Cover

Getting StartedFront panel controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Digital display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Rear panel connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Connecting to a power source . . . . . . . . . . . . . . . . . . . . . . .4

Installing and Maintaining Electrodes . . . . . . . . . . . . . . . . . . . .5Preparing glass electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . .5Installing the combination glass pH electrode . . . . . . . . . . . .5Installing the FET pH electrode . . . . . . . . . . . . . . . . . . . . . . . .6Installing ORP or ISE electrodes . . . . . . . . . . . . . . . . . . . . . . . .6Rinsing electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Storing electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Standardizing for pH Measurement . . . . . . . . . . . . . . . . . . . . . .8Entering buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8The diagnostic electrode test . . . . . . . . . . . . . . . . . . . . . . . . .9Selecting buffers based on 20°C or 25°C . . . . . . . . . . . . . . .11

Using Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11Clearing Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11Reviewing electrode standardization . . . . . . . . . . . . . . . . . .11Selecting buffer sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Standardizing for Millivolt Measurement(Relative Millivolts) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Entering a millivolt standard . . . . . . . . . . . . . . . . . . . . . . . . .13Clearing a millivolt standard . . . . . . . . . . . . . . . . . . . . . . . . .14

Measuring pH or Millivolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14Understanding pH Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Defining pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Measuring pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

The “Error” Icon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18The “CAL Error” Icon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18The “Err °C” Icon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18The “Electrode Error” Icon . . . . . . . . . . . . . . . . . . . . . . . . . . .18Electrode testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18Meter Operation testing . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Meter Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20Technical Assistance . . . . . . . . . . . . . . . . . . . . . . . . Back Cover

1

The CE marking affixed to the equipment indicates that the equipment meetsthe requirements of the following Directive(s).

Council Directive 809/336/EEC “Electromagnetic compatibility (EMC)”

EN-61010-1, “SAFETY REQUIREMENTS FOR ELECTRICAL EQUIPMENT FORMEASUREMENT, CONTROL, AND LABORATORY USE. PART 1.GENERAL REQUIREMENTS”

Applicable European Standards:

EN-55011 ELECTROMAGNETIC EMISSION REQUIREMENTS FOR ISM

Defined immunity to interference:EN 50082-1 Residential, commercial and light industry

Important Note:

The operator shall be responsible for any modifications to Denver InstrumentCompany equipment and for any connections of cables or equipment notsupplied by Denver Instrument and must check and if necessary, correct thesemodifications and connections. On request, Denver Instrument Company willprovide information on the minimum operating specifications (in accordancewith the Standards listed above for defined immunity to interference).

You have purchased a quality precision meter that requireshandling with care.

Read entire contents of this Operation Manual prior to operating your new Denver Instrument meter.

Caution: Changes or modifications not expressly approved by the manufacturer couldvoid the product’s warranty.

Manufactured in the U.S.A. by:

Denver Instrument Company6542 Fig Street • Arvada, Colorado 80004

(303) 431-7255 • (800) 321-1135 • Fax(303) 423-4831

2

Getting Started

3

BASIC

Denver Instrument


pH/mV - press to togglebetween pH and mV mode.

Standardize - press to entereach buffer.

Setup - press to clear buffers,review electrode calibrationor select new autorecog-nized buffers.

Enter - press to select options.

Digital Display

100.0°C%slope rel mV pH

-18.0.0.0Good Electrode Error FETStandardizing ClearMeasuring Set Buffers

2 4 7 10 12 1 3 5 8 10 131.68 4.01 6.86 9.18 12.46

1.08 3.06 4.86 6.79 9.23 12.76

S

StabilityIcon

Temperature

Mode

Front Panel Controls

ResultElectrode

CheckIcons

Prompts

BufferIcons

OperationIcons

Denver Instrument

power refinput

FETATC

Rear Panel Connectors

PowerCable

Connector

Reference ElectrodeConnector

(used with separateReferenceElectrodes)

BNC GlasspH or IonElectrode

Connector

FETElectrode

Connector

ATC(Automatic

TemperatureCompensation)

ProbeConnector

4

Denver Instrument

power refinput

FETATC

ACAdapter

PowerConnector

Connecting to a Power Source

Installing and Maintaining ElectrodesThis meter allows you to use two types of pH electrodes: aglass pH electrode and the Denver Instrument FET (field effecttransistor) pH/ATC electrode. If both types of electrodes areinstalled, the meter will read the FET electrode. NOTE: If bothelectrodes are connected to the meter, do not put them in asolution together because you will get inaccurate measure-ments.

5

Denver Instrument

power refinput

FETATC

1. Remove the protective endcover from electrode.

3. Remove the shorting cap on the BNC connector. Install the com-bination glass pH/ATC electrode by plugging it into the input con-nection (push on and twist to lock) and the ATC connector intothe ATC jack.

2. Before first use of your glass pHelectrode, or whenever theelectrode is dry, soak over-night in an Electrode FillingSolution, KCI solution orElectrode Storage Solution.

6

Denver Instrument

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FETATC

4. Option: Install the optional FET pH/ATC electrode by plugging itinto the FET jack on the back of the meter panel. Allow the FETelectrode to stabilize for one minute prior to use.

Denver Instrument

power refinput

FETATC

5. Option: Install ORP or Ion Selective Electrode pairs by removing theBNC shorting cap and plugging the BNC connector (twist-lock)into the BNC jack. If a separate reference electrode is used, plugthe reference electrode into the ref pin.

ReferenceElectrode

7

6. Rinse and blot-dry elec-trodes between eachmeasurement (do notwipe). Rinse electrodeswith distilled water ordeionized water, or partof the next solution to bemeasured.

7. Store glass pH electrodes inElectrode Filling Solution, KCIsolution or Electrode StorageSolution. Always leave the fill-ing hole open and refill withFilling Solution when the inter-nal solution level gets low.Store FET pH/ATC electrodesdry.

8

Standardizing for pH MeasurementBecause electrodes vary in their response, you must standard-ize your pH meter and electrode to compensate for electrodevariation. The more frequently you standardize, the more accu-rate your measurements. Standardize daily, or more often, foraccurate results.

1. Immerse electrode in a buffersolution. Stir gently. Allow theelectrode to reach a stablevalue.


pH

4.12

2. Press and release the pH/mVbutton until your digital dis-play indicates pH mode. Thisbutton toggles between pHand mV modes.


pH

ClearBuffers

3. Clear existing buffers whendoing a new 2 or 3 point stan-dardization. Use the Setup andEnter buttons to clear existingbuffers and to select a newset of buffers. See page 11.


4. Press Standardize. The meterrecognizes the buffer andflashes a buffer icon. Whenthe signal is stable, or whenyou press Enter, the buffer isentered.

pH

4.00Standardizing

4

9


5. The meter displays the %slopeof the electrode as 100.0%.On entering a second or thirdbuffer, the meter performs adiagnostic check on theelectrode and displays theslope.

%slope

100.04


6. To enter a second buffer,place the electrode in thesecond buffer solution, stir,allow time for the electrodeto stabilize, and pressStandardize again. The meterrecognizes the buffer and dis-plays the first and secondbuffer icons.

pH

7.00Standardizing

4 7


7. Next, the meter performs adiagnostic test of the elec-trode. The display indicateseither Good Electrode orElectrode Error. The meter dis-plays the % slope of the elec-trode.


8. Electrode Error indicates thatyour electrode is not workingproperly. The electroderesponse must be between 90and 105% slope. Measure-ments causing Electrode Errorare not accepted, used orstored by the meter. PressEnter to clear the Error, thentry re-entering the buffer.

%slope

99.4Good Electrode

4 7

%slope

82.3Electrode Error

4

10


9. To set a third standard, placethe electrode in the thirdbuffer solution, stir, allow to sta-bilize, and press Standardize.The results will be the same asin steps 7 and 8, except thedisplay will show three buffericons.


10. After entering each buffer,the Standardizing icon goesoff and the Measuring iconappears on the display toindicate that the meterreturns to Measuring opera-tion.

22.5°CpH

10.03Standardizing

4 7 10


12. The first set of buffers in themeter is used at 25°C inNorth America and, typical-ly, at 20°C in Europe. In pHmode, press Standardizeand Setup together to showthe current buffer tempera-ture setting. Press bothStandardize and Setupagain to toggle betweenthe temperature settings.Press Enter to select the dis-played temperature settingand to return to Measuring.

11. Standardize your meter andelectrode using at least twobuffers with pH values brack-eting the expected pH ofyour samples. Stirring with amagnetic stir bar and stirrerprovides faster electroderesponse.

25°CSet Buffers

2 4 7 10 12

pH

10.00Standardizing

4 7 10

NOTE: The meter continually adjustsfor temperature. Therefore, buffersmay vary slightly from the nominalvalues because of temperature.

11

Using SetupThe Setup button lets you clear all the buffers that you haveentered, review calibration information, or select the bufferset that you want. NOTE: You can escape setup mode at anytime by pressing pH/mV.

1. Press Setup and the meter dis-plays a flashing Clear Buffersicon. Use this step only whenyou wish to clear all buffersyou have entered. To clear allexisting buffers, press Enter.The meter clears all buffersand returns to Measuring.


2. Press Setup again to showelectrode performance. If themeter has accepted twobuffers, it will display GoodElectrode, display the slopebetween the first and secondbuffers and display the twobuffer icons.


3. Pressing Setup again showsthe electrode slope betweenthe second and third buffers(if three buffers have beenentered) and shows the sec-ond and third buffer icons.


4. Press Setup again to display aflashing Set Buffers icon andto display the first buffer seticons.

%slope

99.4Good Electrode

4 7

pH

Set Buffers2 4 7 10 12


pH

ClearBuffers

%slope

98.7Good Electrode

7 10

12


5. Press Enter to select the set ofbuffers shown on the display

orPress Setup again to view thenext set of buffers. Continuepressing Setup to view thethird and fourth buffer sets.


6. Press Enter to select the dis-played buffer set that con-tains the buffer you want touse. Press Setup again, orpress pH/mV at any time, toreturn to Measuring.

NOTE: You may mix buffersfrom different sets.

pH

Set Buffers

1.68 4.01 6.86 9.18 12.46

pH

Set Buffers1 3 5 8 10 13

13

Standardizing for MillivoltMeasurement (Relative Millivolts)You use millivolt measurement for measuring ion concentration andfor measuring redox potential (also called ORP, oxidation reductionpotential). You will normally use an ion selective electrode (ISE), com-bined with a reference electrode, to measure ion concentration. TheISE senses the ion concentration and responds with a millivolt poten-tial. The millivolt readings are then used to determine ion concentra-tions. You will normally use a platinum indicator electrode, combinedwith a reference electrode, to measure redox potential (ORP). ORPmeasurements indicate the oxidizing or reducing capability of a solu-tion. You can use ORP values to monitor or control solutions requiringa set amount of oxidants or reductants.

1. Immerse electrode in a stan-dard solution.


mV

100.0

2. Press the pH/mV button untilyour digital display indicatesmV mode.


3. Press Standardize to enter amV standard and read rela-tive mV.

NOTE: Relative mV mode is notallowed with the FET electrode.


4. When the signal becomesstable, or when you pressEnter, the current absolutemV value becomes zero rela-tive millivolts.

rel mV

0.0Measuring

mV

100.0Standardizing


5. To clear a mV offset andreturn to absolute millivoltmode, press Setup. The meterdisplays a flashing Clear icon,and shows the current rela-tive millivolt offset.


6. To clear the mV standard,press Enter. You then return toabsolute mV mode.

mV

Measuring

rel mV

100.0Clear

14

Measuring pH or Millivolts


Standardizing

1. Standardize your meter.See page 10 (pH) or page15 (mV).

2. Rinse electrode andimmerse in sample solu-tion. Stir gently.


rel mV pH

ErrElectrode ErrorMeasuring

15


Measuring

S

3. Press pH/mV until yourdisplay indicates thecorrect mode.

4. The display shows thecurrent reading in pH,mV, or relative mV units.When the signal is stable,the meter displays the Sicon. The S icon meansthe signal is changing lessthan 0.007 pH or 0.08 mVfrom the prior reading.


rel mV pH

5. You may receive an outof range error, Err, ifyour electrode is notimmersed in a solution.To correct the error,immerse the electrodein a solution.

6. Separate calibrationsfor the glass and FETelectrodes are stored inmemory. Plugging theFET in recalls it’s calibra-tion, unplugging the FETrecalls the glass elec-trode calibration.

Denver

er refinput

FETATC

16

Understanding pH TheoryDefining pHThe measurement of pH plays an important role in identifyingand controlling acidity and alkalinity levels for industry andresearch. pH is a measure of the acidity or alkalinity of a solu-tion and can be represented by this equation:

pH = -log [H+]

with [H+] representing the concentration of hydrogen ions inthe solution. pH is sometimes referred to as the power of thehydrogen ion in a solution.

By using a pH meter, you can determine exact pH levels ofsolutions. For example, rather than say that lemon juice isquite acidic, you can say that lemon juice has a pH of 2.4.An exact pH value can be used to control or measure aciditylevels for manufacturing processes or for basic research.

pH values generally range from 0 to 14, with a pH value of 7being the neutral point, or the value of pure water. pH valuesgreater than 7 represent increasing alkalinity, whereas pH val-ues below 7 represent increasing acidity (Figure 1).

Stro

ng A

cid

Lem

on

Juic

e

Tom

ato

Jui

ce

Co

ffee

Pure

wa

ter

Baki

ng S

od

a

Am

mo

nia

Stro

ng B

ase

Neutral

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

more acidic more basicpH

Figure 1.pH Scale showing the relative acidity or basicity

of some common substances.

Measuring pHTo measure pH with a conventional glass pH electrode, themeter uses a pH-sensing glass bulb that is sensitive to hydro-gen ions. The potential developed at the glass membrane isdirectly related to the pH of the solution.

The glass electrode is paired with a reference electrodewhich completes the electrical measuring circuit and providesa stable reference point. These two electrodes are joined tocreate a combination electrode. The combination glass elec-trode is connected to the pH meter which reads the voltage,converts it to pH units, and displays the result.

Combination Glass pH Electrode

This meter can also use the Denver Instrument Field EffectTransistor (FET) electrode for measuring pH. The FET uses anion-sensitive solid state membrane attached to the transistorto measure the hydrogen ion concentration of a solution. TheFET is paired with a reference electrode that maintains a con-stant potential while the FET responds to the sample.

17

PorousJunction

pH Sensor

ATCTemperatureSensor

ReferenceElectrode

pH-Sensitive FET

ATCTemperatureSensor

ReferenceElectrode

18

Troubleshooting


ErrElectrode Error

1. If the signal from the elec-trode is out of range, the dis-play will show Err. This mayhappen when the electrodeis not in a solution.


Electrode Error

2. The meter will displayElectrode Error when itdetects an error in electroderesponse. During standardiza-tion, the message indicatesthat the electrode is less than90% or more than 105% of thecorrect response. TheElectrode Error message canindicate either a bad elec-trode or bad buffer(s).


Err°C

Error

3. If the meter detects an errorin the temperature probe, thedisplay shows Err°C. If you donot use a temperature probe,the meter uses the defaulttemperature that you set,either 20°C or 25°C.

4. To test the pH electrode,place it in a good pH 7 buffer.Press pH/mV to use the mVmode, and note the millivoltreading. Make sure the meteris in mV mode and not rela-tive mV mode. Repeat foreither a pH 4 or pH 10 buffer.The electrode signal must bewithin the limits shown below(when temperature is near25°C).

Electrode Test

pH 7 0 ± 30 mV

pH 4 159 to 186 mVmore than pH 7

pH10 159 to 186 mVless than pH 7


CalError

5. To test the meter for correct operation, install the BNC (input) shorting cap.Press pH/mV to select the mV mode, and note the mV reading. Make surethe meter is in mV mode and not relative mV mode.If the meter reads 0 +0.3 mV, it is measuring correctly. Note that a long term drift of 0.1mV/monthsince last calibration is specified.

6. If the meter detects a loss ofcalibration or a hardwareerror during its power-up self-test, the display shows CALError. This means the mVaccuracy may be reduced,but pH accuracy after stan-dardization will be the same.Press Enter to continue usingthe meter. If recalibration isdesired, contact TechnicalSupport.

Denver Instrument

power refinput

FETATC

19

Accessories

You can order the following accessories for your pH meter:

Plastic-body pH/ATC Electrode 300728.1

High-performance 300729.1glass-body pH/ATC Electrode

Denver FET pH/ATC Electrode 300486.1

ATC Temperature Probe 300733.1

Free-standing Electrode Arm with Base 300401.1

Meter Lock-down Device 36800110.1

Other electrodes, such as ion selective electrodes and redoxelectrodes are also available. Call your sales representative.

Meter SpecificationspH -1.99 to 19.99 pH

displayed to 0.01 pHaccurate to 0.01 pH

mV -1800.0 to 1800.0 mVdisplayed to 0.1 mVaccurate to 0.3 mV

Temperature -5.0 to 105.0°Cdisplayed to 0.1°Caccurate to 0.4°C

Standardization 0, 1, 2 or 3 buffers

Auto buffer recognition 22 buffers2, 4, 7, 10, 121, 3, 6,, 8, 10, 131.68, 4.0, 6.86, 9.18, 12.461.09, 3.06, 4.65, 6.79, 9.23, 12.75

Auto Temperature CompensationAutomatic electrode slope correction for 90-105%Direct reading with both a glass and FET pH electrode

20

Technical Assistance and ReturnShipping Instructions

Please return the prepaid, pre-addressed Purchase registrationCard to the manufacturer promptly upon your purchase of theproduct. The return of the card is not a condition precedent towarranty coverage.

Contact your local distributor to determine a solution to theproblem. If further technical assistance is needed, contactTechnical support in:

North America – Tel: 1-800-321-1135 or Fax: 303-423-4831United Kingdom – Tel: (0366) 386242 or Fax: (0366) 386204

• A Return Authorization Number from Customer Service isrequired for all returned units.

• Write a detailed description of the unit’s malfunction on thepacking slip.

• Unplug and remove the power supply• Place the pH meter and power supply in the original shipping

carton. Secure he unit with the original packing material. If theoriginal packing is not available, call the Customer Servicenumber. The factory packing material must be used!

• Enclose the packing slip.• Close the carton and secure with appropriate packing tape.• Write the Return Authorization number on the outside of the

carton.

In the U.S. ship to:Denver Instrument Company6542 Fig StreetArvada, Colorado 80004

In the U.K. and Europe ship to:Denver Instrument Company, Ltd.Denver House, Sovereign WayTrafalgar Business Park, Downham MarketNorfolk PE38 9SW England

Upon receipt and inspection of the defective unit, we willpromptly repair or replace the product. Units which have notbeen maintained in accordance with the operating instructions,or have been misused or abused, will be repaired and returnedwith service charges due.

Denver Instrument Company6542 Fig Street • Arvada, Colorado 80004 U.S.A.

1-800-321-1135 • (303) 431-7255 • Fax (303) 423-4831

www.denverinstrument.com

European Office:Denver Instrument Company, Ltd.

Denver House, Sovereign Way • Trafalgar Business ParkDownham Market, Norfolk PE38 9SW • England

BASIC

Enter

Setup

Standardize

pH/mV

Measuring

4

S22.2°C

4.06pH

Denver Instrument

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