Analysis of polyhalogenated carbazoles and two related compounds in earthworms using a modified QuEChERS method with GC/MS and GC/MS/MS

A precise analytical method based on QuEChERS has been proposed for the concurrent determination of 11 polyhalogenated carbazoles (PHCZs), benzocarbazole (BZCZ), and 9H-carbazoles (CZ). The quantification was confirmed by gas chromatography using triple quadrupole tandem mass spectrometry (Shimadzu GC–MS/MS-TQ8040) and gas chromatography coupled mass spectrometry (Agilent 7890A-5973 GC–MS). The developed method was validated by testing the following parameters: linearity, instrument limit of detection (LOD), instrument limit of quantification (LOQ), method limit of detection (MLD), method limit of quantification (MLQ), matrix effect (ME), accuracy, and precision. All compounds showed good linearity in the range of 0.005–0.2 μg/mL with correlation coefficients higher than 0.992. The method demonstrated satisfactory recoveries (ranging from 71.21 to 105.04%) for most of the compounds with relative standard deviation precision (RSD) < 10.46%, except 3-BCZ (Recovery = 67.53%, RSD = 2.83%). The values of LOD and LOQ varied from 0.05 to 0.24 ng and 0.14 to 0.92 ng, respectively, while those of MLD and MLQ ranged from 0.02 to 0.12 ng/g wet weight (ww) and 0.07 to 0.45 ng/g ww, respectively. The developed method represents a reliable tool for the routine analysis of PHCZ congeners in invertebrate animals.