Development of a new QuEChERS method based on dry ice for the determination of 168 pesticides in paprika using tandem mass spectrometry

This study describes a new QuEChERS method referred to as the dry ice-partitioning QuEChERS method. This current method can be differentiated from the other QuEChERS methods in the sense that it uses dry ice rather than salts or buffers to extract and partition pesticides in the first extraction step. The dry ice-partitioning QuEChERS method consists of extraction method A (for detection of the acetonitrile layer) and extraction method B (for detection of both acetonitrile and aqueous layers). The extraction efficiency was then compared with the citrate-buffering QuEChERS method by means of recovery. Recovery values of the tested 168 pesticides were above 76%, with relative standard deviations of less than 20%. Certain problematic pesticides, including benfuracarb, carbosulfan, dichlofluanid, probenazole, pymetrozine, tolylfluanid, TFNA, and TFNG evidenced acceptable recoveries via the dry ice-partitioning QuEChERS method compared to the less than 70% recoveries of the citrate-buffering QuEChERS method examined herein. The matrix effect of paprika on the method developed herein was not significant, and matrix-matched calibration was performed well, with an r(2) >= 0.99. The dry ice-partitioning QuEChERS method is capable of detecting the aqueous layer as well as the acetonitrile layer; this interesting feature makes it worth in application as an alternative QuEChERS method for the multiresidue analysis of pesticides within a broad polarity range in various matrices. (C) 2011 Elsevier B.V. All rights reserved.