Modified QuEChERS in combination with dispersive liquid-liquid microextraction based on solidification of the floating organic droplet method for the determination of organophosphorus pesticides in milk samples.
In this work, a rapid, environment friendly and sensitive method was established for the extraction and analysis of five organophosphorus pesticides (OPPs) (chlorpyrifos, chlorpyrifos-methyl, isocarbophos, malathion and phorate) in milk samples by means of gas chromatography-flame photometric detection. The pesticides were first extracted with acetonitrile from milk samples by using the modified "quick, easy, cheap, effective, rugged, and safe" (QuEChERS) method. No other clean-up was required after extraction. Then the above-mentioned acetonitrile extract was concentrated by using the dispersive liquid-liquid microextraction combined with solidification of floating organic droplets technique. Several factors that could influence the extraction efficiency, such as type of extraction solvent, disperser solvent, volume of extraction and disperser solvent, salt effect, sample pH, and extraction time, were investigated and optimized. As a result, 15 µL of 1-dodecanol were used as the extractant because of its lower toxicity, 300 µL methanol was chosen as dispersant and the extraction time was set to 1 min. Under the optimized conditions, good linearity was exhibited from 0.01 to 1.0 mg/L with the correlation coefficients higher than 0.9968. The limits of detection of the five OPPs were ranged in 0.1-0.3 μg/L, and the limits of quantification were at the range of 0.3-1.0 μg/L. Moreover, the recoveries of the target analytes from milk samples at spiking levels of 0.01, 0.05 and 0.1 mg/L were between 80.5 and 106.5% with the relative standard deviations varied from 3.6 to 6.3%. This method has been successfully applied to detect OPPs in real milk samples.
Key Laboratory of Nature Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou 510642, China.
Xue-xue
XX
Miao
Key Laboratory of Nature Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou 510642, China.
Deng-biao
DB
Liu
Key Laboratory of Nature Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou 510642, China.
Ya-ru
YR
Wang
Key Laboratory of Nature Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou 510642, China.
Yuan-yuan
YY
Yang
Key Laboratory of Nature Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou 510642, China yxyhyxy@scau.edu.cn.
Xiao-yun
XY
Yang
Hunan Rice Research Institute, Hunan Academy of Agricultural Science, Changsha 410125, China.
Hao-ru
HR
Gong
D000818:Animals; D057230:Limit of Detection; D059627:Liquid Phase Microextraction; D008892:Milk / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000032:analysis*; D010575:Pesticides / Q000032:analysis*
D009943:Organophosphorus Compounds; D010575:Pesticides