Belete Eshetu Gebreyohannes

13 Sept. 2016

Optimization of dispersive liquid-liquid microextraction for the

determination of polybrominated diphenyl ethers in water by Gas

Chromatography Time of Flight Mass Spectrometry

1

Contents

Introduction

Methods

Results and Discussions

Conclusions

Acknowledgments

2

IntroductionWhat are PBDEs?

organo bromine compounds

• PBDEs exist as mixtures of similar chemicals called

congeners.

• 209 congeners

• 1 to 10 bromines, Mono smallest and Deca largest congener

• Similar to PCBs and Dioxins in regards to number of

congeners [1]

31. Agency for toxic substances and Disease registry, 2004

Chemical Structures of PBDEs and Others similar POPs

Polychlorinated biphenyls

(PCBs)

Polychlorinated dibenzo-p-

dioxins (PCDDs)

4

Polybrominated biphenyls

(PBBs)

Why……

• PBDEs are Flame-retardant chemicals added to plastics

and foam products to make them nonflammable

• Flame retardants save lives

• The 3 major classes of brominated flame retardants are

Penta, Octa and Deca.

5

Why NOT

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• PBDEs do not bind chemically to polymers in materials

• Global, transboundary problem

• Persistent in environment

• Bioaccumulate

• Toxic to animals

• Certain congeners have been banned completely and are

currently in the list of the Stockholm convention [3]

3. Stockholm Convention, 2010

• Development of faster and inexpensive sample preparation

techniques are an important issue in chemical analysis

• Current trends are towards:

Simplification , Miniaturization and use of green solvents of

sample preparation

• LPME is miniaturized extraction techniques which include

SDME, HF-LFME, DLLME

Extraction Techniques for Analysis of

PBDEs

7

• LPME is miniaturized extraction techniques which include SDME, HF-

LFME, DLLME .

• DLLME is recent technique that has been successfully applied to the

extraction and concentration of a wide variety of POPs from different matrix.

• DLLME was introduced in 2006 by Assadi et al. for the preconcentration of

organic analytes from aqueous matrices.

• It is fast, inexpensive, easy to operate with a high enrichment factor and

consumes low volume of organic solvent [4]

84. A. P. Birjandi, A. Bidari, F. Rezaei, M. R. M. Hosseini, and Y. Assadi, “J.

Chromatogr. A, 2008,vol. 1193, no. 1-2, pp. 19–25.

Principle of DLLME

9

Analytes Extraction Determination Analytical Parameters Ref

BDEs 47, 99, 154,

183

TA-IL−DLLME Sample volume 5mL,

dispersive solvent MeOH (1 mL),

extraction solvent [C8MIM] [PF6](40

μL)

HPLC–DAD LR 500–500000 ng/L,

RSD 1.0–3.8%,

LOD 100–400 ng/L,

Recovery 81.0–127.1%

[5]

BDEs 28, 47, 85,

99, 100, 153, 154

SPE - DLLME Sample volume 5 mL,

ACN (1 mL), 1,1,2,2-tetrachloroethane

(22 μL)

GC–ECD LR 0.1–100 ng/L

(BDEs 28, 47), 0.5–500 ng/L, others;

RSD 4.2–7.9%;

LOD 0.030–0.15 ng/L;

recovery 66.8–94.1%

[6]

BDEs 28, 47, 99,

209

DLLME Sample volume 5 mL, ACN (1

mL), tetrachloroethane (20 μL)

HPLC–DAD LR 50–50 000 ng/L (BDEs

28, 99), 100–100000 ng/L

(others); RSD 3.8–6.3%;

LOD 12.4–55.6 ng/L;

recovery 87.0–114.3%

[7]

BDE-209 DLLME Sample volume 5 mL,

disperser solvent THF (1 mL),

extraction solvent tetrachloroethane

(22 μL)

HPLC–UV LR 1000–500000 ng/L,

RSD 2.1%, LOD 200 ng/L,

recovery 89.9–95.8%

[8]

BDE-100 DLLME Sample volume 25 mL, ACN

(1 mL), Chlorobenzene ( 80μL)

GC-MS LR 5-10000 ng/L,

RSD 12 %, LOD 0.5 ng/L,

recovery 91–107 %

[9]

BDEs 47, 153,

154, 100 and 183 DLLME GC-TOF-MSThis

study

10

5. Zhao, A., Wang, X., Ma, M., Wang, W., Sun, H., Yan, Z.,Xu, Z., and Wang, H., Microchim. Acta, 2012, vol. 177,nos. 1–2, p. 229

6. Liu, X., Li, J., Zhao, Z., Zhang, W., Lin, K., Huang, C., and Wang, X., J. Chromatogr. A, 2009, vol. 1216, no. 12,p. 2220.

7 . Li, Y., Wei, G., Hu, J., Liu, X., Zhao, X., and Wang, X., Anal. Chim. Acta, 2008, vol. 615, no. 1, p. 96.

8 .Li, Y., Hu, J., Liu, X., Fu, L., Zhang, X., and Wang, X., J. Sep. Sci., 2008, vol. 31, no. 13, p. 2371.

Monica S.F. Santos ,Jose Luis Moeira , Luis M.Maderia ,Arimina Alvias ,Determination of PBDEs in water , J.Anlcal.Chem.2015 Vol. No. 11 pp 1390-1400

• The application of this promising technique for PBDEs is

still very limited

Analytical methodologies based exclusively on DLLME

technique were found for only a few PBDE Congeners

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• The main objectives of the study are:

• Development of simple, cost-effective and environmentally friendly

sample preparation techniques for the determination and quantification

of selected Polybrominated diphenyl ethers in water by Gas

Chromatography Time of flight mass spectrometry.

Objectives

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• To develop DLLME technique for BDEs 47, 100, 153,154 and 183 by GC TOF

MS.

• To validate DLLME technique based on the validation parameters.

• To apply the DLLME technique in real samples

Specific Objective

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Some of selected analytes of PBDEs Congeners and their Structures

Structure Congener Name

BDE-47 2,2′,4,4′-tetra-bromodiphenyl

ether

BDE-100 2,2′,4,4′,6-penta-bromodiphenyl

ether

BDE-153 2,2′,4,4′,5,5′-hexa-bromodiphenyl

ether

BDE-154 2,2′,4,4′,5,6′-hexa-bromodiphenyl

ether

BDE-183 2,2′,3,4,4′5,6′- hepta

bromodiphenyl ether

Methods of analysis

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5 ml ultra pure water

100 µl PBDE mix standards was spiked to be the final concentration of 20 µg/l

50 µl extraction solvent + 1000 µl disperser solvent were mixed .

centrifugation @ 4000 rpm for 5 min was applied

The sediment was removed and added in to 1.5 ml vial

1µl Injected in to GC-TOF-MS

• Column : HP-5MS, 30 m x 0.25 mm ID, 0.10 μm film thickness

• Detector: LECO Pegasus Time of -Flight Mass Spectrometer

• Transfer Line Temperature: 280 ºC

• Source Temperature: 250 ºC

• Detector Voltage: -1850 Volts

• Column Oven: 60 ºC for 2 min, to 300 ºC at 25 ºC/min, hold for 8.4 min .

• Inlet: Splitless 250 ºC

• Injection: 1 μL

• Carrier Gas: Helium, 1.0 mL/min corrected constant flow

• Run time: 20 min

GC-TOFMS Condition

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Chromatogram of PBDEs

Fig. 1 Chromatogram of PBDEs; water sample volume 5 mL; disperser solvent (acetone) volume 1.00 mL; extraction

solvent (Teterachloroethane ) volume 50 µL ; concentrated with 50 µL hexane; 1 µL injected in to GC-TOFMS

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Results and Discussions

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0

20000

40000

60000

80000

100000

120000

140000

Teterachloroethane Teterachloroethylene Chlorobenzene Chloroform

Peak a

rea o

f E

xtr

acti

on

so

lven

t

Type of Extraction solvent

Selection of extraction solvent

BDE-47

BDE-100

BDE-154

BDE-153

BDE-183

Fig. 2 Effects of Extraction solvent

Selection of dispersive solvent

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0

100000

200000

300000

400000

500000

600000

Acetonitrile Acetone Methanol

Peak a

rea o

f D

isp

ers

ive s

olv

en

t

Type of Dispersive solvent

BDE-47

BDE-100

BDE-154

BDE-153

BDE-183

Fig. 3 Effects of dispersive solvent

20

0

100000

200000

300000

400000

500000

600000

700000

800000

900000

30 µl 40 µl 50 µl 60 µl 70 µl

Peak a

rea o

f E

xtr

acti

on

So

lven

t V

olu

me

Extraction Solvent Volume

BDE-47

BDE-100

BDE-154

BDE-153

BDE-183

Fig. 4 Effect of extraction solvent volume

Selection of extraction solvent volume

21

0

200000

400000

600000

800000

1000000

1200000

1400000

1600000

1800000

500 µl 1000 µl 1250 µl 1500 µl

Peak a

rea o

f d

isp

ers

ive s

olv

en

t

Volume of dispersive solvent

BDE-47

BDE-100

BDE-154

BDE-153

BDE-183

Fig. 5 Effect of dispersive solvent volume

Selection of dispersive solvent volume

• Tetrachloroethane was found to be best extraction solvent

and acetone the best dispersive solvent

• Extraction solvent volume at 30 µl had high extraction

efficiency

• Dispersive solvent at 1000 µL had high extraction efficiency

.

Conclusions

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Further work

• Validate DLLME on the optimized parameters

• Apply the validated technique in real sample

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I Would like to express my earnest appreciation to:-

Prof. Simiso Dube and Prof Matthew M. Nindi

All UNISA, Analytical Chemistry research Group

CHROMSA and SAAMs

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Acknowledgements

Thank you !!!

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