Direct Grignard pentylation of organotin-contaminated lard samples followed by capillary gas chromatography with flame photometric detection

During a recent investigation of the organotin-contaminated lard samples, a simple method was developed by direct Grignard pentylation of lard samples and capillary gas chromatography with flame photometric detection using quartz surface-induced tin emission. Using HP-1 capillary column with temperature programming and FPD detector, pentylated tri-, di-, monometyltin, dioctyltin and Sn(IV) can be base-line separated and detected within 20 min. The analysis of pentylated tin compounds by GC–MS confirmed the existence of methyltins and inorganic tin in lard samples, which was agreeable with the results obtained by GC–FPD. The content of organotin compounds was calculated by internal standard method in which methyltripropyltin (MeSnPr3) acted as internal standard. The results showed that these samples were heavily contaminated with mg/g levels of dimethyltin, μg/g levels of tri- and monomethyltin. Among them, one sample contained mg/g level of dioctyltin and one contained a little of inorganic form of Sn(IV). The recoveries of tri-, di- and monomethyltin were 95.7%, 105.5% and 105.7%, respectively.