Simultaneous determination of phoxim and its photo-transformation metabolite residues in eggs using liquid chromatography coupled with electrospray ionization tandem mass spectrometry.
The principal objective of this study was to develop an appropriate, sensitive, and selective method for the simultaneous quantitative determination of phoxim and its photo-transformation product, O,O-diethyl alpha-cyanobenzylideneamino-thiophosphonate (DCTP) in both chicken and quail eggs. Eggs (1 g) were blended with anhydrous magnesium sulfate (1 g) for sample pretreatment and extracted with acetonitrile. The extracts were then further purified with SPE silica gel tubes deactivated with trimethylamine. Residues were analyzed via a reversed phase-liquid chromatography-tandem mass spectrometry (RP-LC-MS/MS) in positive-ion electrospray ionization (ESI) mode. Tebufenozide was utilized as an internal standard for the quantification of phoxim and its metabolite residues. The identification and quantification of analytes were based on ion transitions monitored by multiple reaction monitoring (MRM). LC-MS/MS analysis was performed from 0.02 to 1 mg kg(-1) and correlation coefficients (r(2)) ranging from 0.998 to 0.999 were obtained for both analytes in blank egg extracts. The relative standard deviations (RSDs) of intra- and inter-day variations ranged from 2.1% to 6.7% and from 2.8% to 6.4% for phoxim and DCTP in chicken and quail eggs. At all levels of fortification (0.02, 0.05, and 0.125 mg kg(-1)), the recoveries fell within a range of 81.3% to 93.6% for phoxim and 83.3% to 90.1% for DCTP. The matrix effect was <2%, due to the partial dilution of the sample. Decision limits (CCalpha) and detection capabilities (CCbeta) were in the range of 0.0005-0.0044 and 0.0054-0.0224 mg kg(-1), respectively. The method was evaluated further by analyzing real samples purchased from markets. All chicken and quail egg samples were free from residues of the target compounds.
Lee
Jung Han
JH
Department of Chemistry and Research Institute of Life Science, Gyeongsang National University, Jinju 660-701, Republic of Korea.
Park
Semin
S
Jeong
Won Young
WY
Park
Hyung Jin
HJ
Kim
Hae Gyeong
HG
Lee
Soo-Jung
SJ
Shim
Jae-Han
JH
Kim
Soo Taek
ST
Abd El-Aty
A M
AM
Im
Moo Hyeog
MH
Choi
Ok Ja
OJ
Shin
Sung Chul
SC
D056148:Chromatography, Reverse-Phase; D004531:Eggs / Q000032:analysis*; D009946:Organothiophosphorus Compounds / Q000032:analysis* / Q000378:metabolism; D010573:Pesticide Residues / Q000032:analysis* / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
D009946:Organothiophosphorus Compounds; D010573:Pesticide Residues; C003135:phoxim