A quantitative acetonitrile extraction with dispersive solid-phase clean-up and subsequent high performance hydrophilic interaction liquid chromatography-atmospheric pressure electrospray ionization mass spectrometry (HILIC-ESI-MS-MS) analysis is outlined for the determination of propylenethiourea (PTU, 4-methylimidazolidine-2-thione), the main degradation product of propylenebisdithiocarbamate (PBDC). In the present study, the quick, easy, cheap, effective, rugged and safe method (QuEChERS) methodology was adopted for the extraction of PTU from tomato matrix. The synthesis and impurity profiling of a new internal standard compound (4,5-dimethylimidazolidine-2- thione) is also reported, which was used instead of tris(1,3-dichlorisopropyl) phosphate due to poor ionization at elevated acetonitrile levels. The effect of chromatographic parameters on the HILIC separation and MS detection was studied. Coupling of hydrophilic interaction liquid chromatography with mass spectrometric detection was advantageous not only in view of separation and ionization efficiency but also in direct injection of the QuEChERS extract without the need for solvent exchange.
- Column liquid chromatography-tandem mass spectrometry
- Pesticide metabolite residues
ASJC Scopus subject areas
- Analytical Chemistry
- Clinical Biochemistry
- Organic Chemistry