A new method is described based on ultrahigh-performance liquid chromatography-mass spectrometry (UHPLC) with electrospray mass spectrometry detection for comprehensive quantitative analysis of 66 polyethoxylated tallow amine (POE-tallowamine) homologs in citrus. Efficient separation, reduced band broadening, and high sensitivity were achieved by employing an acetonitrile-aqueous solution containing a 10 mM ammonium formate gradient on a hydrophilic interaction chromatography (HILIC) column with a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method. The quantitative accuracy and precision of the method were improved by the use of matrix-matched calibration standards. At spiked levels of (50 + 250) μg/kg, (200 + 1000) μg/kg, and (500 + 2500) μg/kg POE-5 and POE-15 (1:5), the average recoveries of the POE-tallowamine homologs ranged from 71.9 to 112%, with RSDs < 16.6%. The limits of detection (LODs) and limits of quantification (LOQs) for POE-tallowamine homologs were 0.01-2.57 and 0.03-8.58 μg/kg, respectively. The method was successfully applied to determine POE-tallowamine in citrus samples from typical Chinese regions in 2021. POE-tallowamine was detected in all 54 samples, and the highest concentration (143 μg/kg) of POE-tallowamine was found in Jelly orange from Zhejiang Province, which might indicate a higher usage and demand of glyphosate herbicides in Zhejiang.
Keywords: QuEChERS; citrus; pesticide adjuvant; polyethoxylated tallow amine; ultrahigh-performance liquid chromatography-mass spectrometry.
Copyright © 2022 Li, Wang, Li, Chen, Jin, Shao, Wang and Jin.