A method for the determination of glyphosate (Gly), glufosinate (Glu) and aminomethylphosphonic acid (AMPA) was developed and validated in tea samples (loose leaf and tea-bag tea types) using reversed-phase high performance liquid chromatography (RP-HPLC) coupled with tandem mass-spectrometry. The sample preparation method was consists of: extraction by acidified water followed by SPE on Oasis HLB, derivatization by FMOC-Cl, concentration and usage of another SPE stage on Oasis WCX. The limit of quantification (LOQ) of 0.05 mg/kg was reached for Gly and Glu; 0.1 mg/kg for AMPA. Recovery values ranged from 94% to 115% in depending of analyte and concentration level. The RSD values were ranged from 3 to 15%. The correlation coefficients were higher than 0.99. The method was applied in 2021-22 for analysis of tea samples, which revealed about 82% of positives above LOQ level and about 38% of positives with concentrations more than 0.2 mg/kg. Three samples with concentrations of glyphosate between 1-1.07 mg/kg were found. The glyphosate content in green tea was less in 3 times, in comparison with black tea.

A confirmatory method was developed and validated for determination of glyphosate (Gly), glufosinate (Glu) and aminomethylphosphonic acid (AMPA) in honey using reversed-phase high performance liquid chromatography (RP-HPLC) coupled with tandem mass-spectrometry (MS/MS). The sample preparation approach consists of extraction by acidified solutions followed by SPE on Oasis HLB, derivatization by FMOC-Cl, concentration and another SPE stage on Oasis WCX. The limit of quantification (LOQ) of 0.05 ppm was reached for Gly, AMPA and Glu. All accuracy values ranged from 85% to 110% for all analytes using both primary and secondary quantitative ion transitions (RSD ≤ 10%). Correlation coefficients were higher than 0.99. The method was applied in 2018-19 for monitoring of honey samples, which revealed agricultural territories with intensive use of glyphosate.

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