The Malaysian Journal of Analytical Sciences Vol 15 No 2 (2011): 232 – 239

 

 

 

DETERMINATION OF ORGANOPHOSPHORUS PESTICIDES BY DISPERSIVE LIQUID-LIQUID MICROEXTRACTION COUPLED WITH GAS CHROMATOGRAPHY-ELECTRON CAPTURE DETECTION

 

(Penentuan Pestisid Organofosforus dengan Pengekstrakan Cecair-Cecair Serakan berganding dengan Kromatografi Gas-Pengesanan Penangkap Elektron)

 

Mohd Marsin Sanagi^1,2*, Siti Umairah Mokhtar¹, Mazidatul Akmam Miskam¹, Wan Aini Wan Ibrahim^1,2

 

¹Department of Chemistry, Faculty of Science,

Universiti Teknologi Malaysia,

 81310 UTM Johor Bahru, Johor, Malaysia

²Ibnu Sina Institute for Fundamental Science Studies,

Nanotechnology Research Alliance, UniversitiTeknologi Malaysia,

81310 UTM Johor Bahru, Johor, Malaysia

 

*Corresponding author: marsin@kimia.fs.utm.my

 

 

Abstract

A simple, rapid and sensitive method termed as dispersive liquid–liquid microextraction (DLLME) combined with gas chromatography-electron capture detector (GC-ECD) was developed for the determination of selected organophosphorus pesticides (OPPs) namely chlorpyrifos, dimethoate and diazinon in water sample. In this method, a mixture of carbon disulfide,  CS₂ (extraction solvent) and methanol (disperser solvent) was rapidly injected using syringe into the 5.00 mL water sample to form a cloudy solution where the OPPs were extracted into the fine droplets of extraction solvent. Upon centrifugation for 3 min at 3500 rpm, the fine droplets were sedimented at the bottom of the centrifuge tube. Sedimented phase (1μL) was injected into the GC-ECD for separation and determination of OPPs. Important extraction parameters, such as type of disperser solvent, volume of extraction solvent and volume of disperser solvent were investigated. The optimized conditions for DLLME of the selected OPPs were methanol as disperser solvent, 30 μL of extraction solvent (CS₂) and 1.0 mL of disperser solvent (methanol). Under the optimum extraction conditions, the method showed good linearity in the range of 0.1 to 1.0 μg/mL with correlation coefficient (r²), in the range of 0.9976 to 0.9994 and low limits of detection (LOD) between 0.047 and 0.201 μg/mL. The proposed method provided acceptable recoveries (72.67- 144%) with good RSDs ranging from 2.74% to 7.48%. This method was successfully applied to the determination of OPPs in water samples obtained from a golf course and chlorpyrifos and diazinon were detected at concentration 0.18 μg/mL and 0.07 μg/mL, respectively.

 

Keywords: Dispersive liquid–liquid microextraction; GC-ECD; Organophosphorus pesticides

 

References

1.       Fu, L., Liu, X., Hu, J., Zhao, X., Wang, H., Wang, X., (2009). Application of Dispersive Liquid Liquid Microextraction for the Analysis of Triazophos and Carbaryl Pesticides in Water and Fruit Juice Samples.Anal.Chim.Acta,632, 289-295.

2.       Zang, X.H., Wu, Q.H., Zhang, M.Y., Xi, G.H., Wang, Z. (2009). Developments of Dispersive Liquid –Liquid Microextraction Technique.Chin. J. Anal. Chem.37, 161-168.

3.       Wan, H.B., Wong, M.K., Mok, C.Y. (1996). Pesticides in Golf Course Waters Associated with Golf Course Runoff. Environ.Contamin.Toxicol.,56, 205-209.

4.       Wan Ibrahim, W.A., Farhani, H.,Sanagi, M.M.and Aboul-Enein, H.Y. (2010).Solid phase microextraction using new sol–gel hybridpolydimethylsiloxane-2-hydroxymethyl-18-crown-6-coated fiber fordetermination of organophosphorous pesticides.J. Chromatogr. A.1217, 4890–4897.

5.       Zhao, E., Zhao, W., Han, L., Jiang, S. and Zhou, Z. (2007). Application of Dispersive Liquid Liquid Microextraction for the Analysis of organophosphorus Pesticides in Watermelon and Cucumber. J. Chromatogr. A.1175, 137-140.

6.       Xu, H., Liao, Y.and Yao, J. (2007). Development of a Novel Ultrasound-assisted Headspace Liquid-phase Microextraction and its Application to the Analysis of Chlorophenols in Real Aqueous Samples.J. Chromatogr. A. 1167, 1-8.

7.       Liu, X.; Chen. X.; Yang, S. and Wang, X. (2007).Comparison of Continuous-flow Microextraction and Static Liquid-phase Microextraction for the Determination of p-toluidine in Chlamydomonasreinhardtii.J. Sep. Sci.30, 2506-2512.

8.       Sanagi, M.M., See, H.H., Wan Ibrahim, W.A. andAbu Naim, A. (2007). Determination of pesticides in water by cone-shaped membrane protectedliquid phase microextraction prior to micro-liquid chromatography. J.Chromatogr. A, 1152, 215–219.

9.       Huan, Z.X, Hua, W.Q., Yue, Z.M., Hong, X.G.and Zhi, W. (2009). Developments of Dispersive Liquid-Liquid Microextraction Technique.Chin. J. Anal. Chem.37(2), 161-168.

10.    Xiong, J. and Hu, B. (2008). Comparison of Hollow Fiber Liquid Phase Microextraction and Dispersive Liquid-Liquid Microextraction for the Determination of Organosulfur Pesticides in Environmental and Beverages Samples by Gas Chromatography with Flame Photometric Detection.J. Chromatogr. A.1193, 7-18.

11.    Liu, Y., Ercheng, Z., Wentao, Z., Haixiang, G. and Zhiqiang, Z.(2009). Determination of Four Heterocyclic Insecticides by Ionic Liquid Dispersive Liquid–Liquid Microextraction in Water Samples.J. Chromatogr. A.1216, 885–891.