Comparison of extraction solvents and conditions for herbicide residues in milled rice with liquid chromatography-diode array detection analysis (LC-DAD)

• Published in: Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment Chemistry, analysis, control, exposure & risk assessment, 2010-02, Vol.27 (2), p.206-211
• Main Authors: Niell, S., Pareja, L., Geis Asteggiante, L., Cesio, M.V., Heinzen, H.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Cereal and baking product industries; Chromatography; chromatography - high-performance liquid chromatography (HPLC); Chromatography, High Pressure Liquid - methods; Comparative analysis; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; Herbicides; Herbicides - analysis; Limit of Detection; Methods of analysis, processing and quality control, regulation, standards; Oryza - chemistry; Oryza sativa; Reproducibility of Results; Rice; Solvent extraction processes; Solvents - chemistry; Spectrophotometry, Ultraviolet - methods
• ISSN: 1944-0049; 1944-0057
• DOI: 10.1080/19440040903296246

Different extraction procedures and clean-up methods were compared in order to develop a sample preparation procedure for the multi-residue analysis of six post-emergence herbicides (metsulfuron methyl, bensulfuron methyl, pyrazosulfuron ethyl, bentazone, bispyribac sodium and cyhalofop butyl) in rice grains followed by liquid chromatography-diode array detection (LC-DAD). Optimum results were obtained dispersing milled rice grain in water, followed by the addition of 1% acetic acid in acetonitrile, MgSO 4 and sodium acetate as a modification of the quick, easy, cheap, effective, rugged and safe (QuEChERS) method but no primary and secondary amine (PSA) sorbent was added due to the acidic nature of the herbicides. The method was further expanded to other post-emergence herbicides (quinclorac, clomazone and propanil). Except for quinclorac, which cannot be analysed with this method, the recoveries of the other eight herbicides were in the range 73-111%, with relative standard deviations lower than 12%. Limits of detection (LODs) ranged from 0.03 to 0.08 mg kg −1 . A single analyst can extract twelve samples in 4 h. The method presented here allows the simultaneous residue determination of the most common post-emergence herbicides employed in cultivating rice. It is simple, rapid, sensitive, and can be applied routinely to polished rice grain herbicide residue analysis.