Abstract: An analytical method for simultaneous determination of the results of two herbicides, pinoxaden, clodinafop-propargyl, and the herbicide safety agent cloquintocet-mexyl in barely was developed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) combined with quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction. The samples were extracted with acetonitrile, and cleaned up with C18 and N-propyl ethylenediamine (PSA). The analytes were then separated with a reversed phase C18 column (XBridge) by gradient elution with a mixture of 0.1% formic acid solution and acetonitrile as the mobile phase. The instrument was operated under the multiple reaction monitoring (MRM) mode with positive electrospray ionization and the analytes were quantified?by matrix matched external standard method. Good linearity was obtained in the concentration range of 0.1–100 μg/L with correlation coefficients no less than 0.999 6. The limits of detection (LODs) of the method were 0.05, 0.02 and 0.01 μg/L for pinoxaden, clodinafop-propargyl and cloquintocet-mexyl, respectively. The average recoveries of the analytes at three spiked concentration levels (determined according to the residue limits of the national standard for wheat) were 76.87%–103.55%. The repeatability, expressed as relative standard deviations (RSD), ranged from 2.4% to 9.2% (n = 5). The method confirmed its applicability to marketed barley grains and seedling flour. This method provides technical support for the determination of pinoxaden residues in barley products.

Key words: barley, pinoxaden, clodinafop-propargyl, cloquintocet-mexyl, QuEChERS, high performance liquid chromatography-tandem mass spectrometry