Miniaturized dielectric barrier discharge-atomic emission spectrometer for pesticide: Sensitive determination of thiram after derivatization with mercurial ion

A novel method was developed to sensitively determine thiram (which we selected as a representative large molecular organic pesticide) using miniaturized dielectric barrier discharge-atomic emission spectrometry (DBD-AES), based on the determination of free mercurial ion (Hg2+) from Hg labeled thiram complex. The disulfide bond (SS) in thiram was reduced to sulfhydryl (SH) using tris(2-carboxyethyl)phosphine (TCEP), and inorganic Hg2+ was used as the derivatization reagent. It was found that SnCl2 could selectively reduce only free Hg2+ to Hg0 vapor in the presence of Hg2+-labeled thiram complex, which could be separated from sample matrices for sensitive DBD-AES detection. Under the optimized conditions, this method provided high sensitivity for thiram determination, with limits of detection as low as 0.0003 mg kg−1 and linear dynamic ranges of 0.001-0.01 mg kg−1. This analytical method performs better than the traditional analytical methods, demonstrating the potential usefulness and versatility of this new Hg-labeled DBD-AES system.