Study On Analytical Method Of Methyltin And Ethyltin In Food

Organotins (OTCs) are widly applied in industry and agriculture, which cause pollution and environment problem. Low level of OTCs in the environment, which can enter human bodies by food chain, may result in harmful effects on lives. And the highest toxicity is the trisubstituted compounds. So it is necessary to establish some new and rapid methods for OTCs detection. In the study, some analytical methods for simultaneous determination of dimethyltin, trimethyltin and triethyltin in food were developed by chromatography and hyphenated techniques. Main research results are as follows:1. A new method for simultaneous determination of dimethyltin (DMT), trimethyltin (TMT) and triethyltin (TET) in wine was established by GC-FPD. The organotins were derivatived by NaBEt4, extracted by hexane, and then analyzed by GC-FPD. The derivation conditions were optimized. Calibration curve was linear in the range of0.2-2.5mg/L, and the correlation coefficient for dimethyltin, trimethyltin, and triethyltin were0.9992,0.9980,0.9991, respectively. Limits of detection were0.0161mg/L,0.0167mg/L,0.0110mg/L, respectively. The average recoveries obtained from samples spiked with standards at the concentration levels of0.5mg/L and2.0mg/L were in the range of67.6%-103.5%, with RSD in the range of5.14%-18.46%. The method was applied to the determination of organotin compounds in wine with satisfactory results.2. Dimethyltin, trimethyltin and triethyltin were determined in laver by GC-MS with ultrasonic extraction. The organotins were derivatived with NaBEt4, and extracted by ultrasonic, then cleaned up by activated carbon. After that, the extracts were analyzed by GC-MS. Calibration curve was linear in the range of0.02-2.5mg/L, and the correlation coefficient for dimethyltin, trimethyltin and triethyltin were0.9980,0.9991and0.9985, respectively. Limits of detection were0.0043mg/L,0.0038mg/L and0.0026mg/L, respectively. The average recoveries obtained from samples spiked with standards at the concentration levels of0.05mg/L,0.5mg/L and2.0mg/L were in the range of65.3%-95.7%, with RSD in the range of5.14%-9.26%. The method was applied to the determination of organotin compounds in real sample with satisfactory results.3. The high performance liquid chromatography-inductively coupled plasma mass spectrometry detection (HPLC-ICP-MS) analytical method was developed for the simultaneous determination of dimethyltin, trimethyltin and triethyltin in water. The sample was extracted with dichloromethane-0.2%tropolone (10:1, v:v) by liquid-liquid method, then concentrated and cleaned up by membrane. After that, the extracts were determined by HPLC-ICP-MS. The results present the good linearities between analytical signal and analyte concentration in the range of0.002-0.05mg/L with the linear correlation coefficients of0.9986,0.9987and0.9997. For DMT, TMT and TET, limits of detection were0.00172mg/L,0.00075mg/L,0.00127mg/L, respectively. The average recoveries at the concentration levels of5.0,20.0and40.0μg/L was in the range of79.7%-99.6%, with RSD in the range3.5%-11.3%. The method was successfully applied to the determination of DMT, TMT and TET in water.