Rapid Method for Determination of Phosphine Residues in Wheat

摘要

A rapid method for spectrophotornetric determination of phosphine residues in wheat has been developed. PhospMne-fumigated wheat kernels were added with 10% sulfuric acid in a gas-tight flask, and phosphine was released into the headspace by microwaveirradiation. Phosphine was spectrophotometrically determined after reaction with silver nitrate. A good linearity of the calibration curve was obtained with wheat spiked at levels ranging from 0.035 to 0.230 mu g/g with correlation coefficient (r) of 0.9965 and a detection limit of 0.026 mu g/g. The total time of analysis was 10 min. Headspace analysis was also performed by micro-gas chro-matography (GC) with a thermal conductivity detector (micro-GC-TCD). Results obtained with the spectrophotornetricand micro-GC-TCD methods showed good correlations with those obtained with the most widely used GC with nitrogen-phosphorus detector with r values of 0.9940 and 0.9946, respectively.