QuEChERS Sample Preparation for LC/MS and LC/UV Determination of Carbendazim and Other Conazole Fungicides in Orange Juice

IN T RODUC T ION QuEChERS methodology is commonly used for sample preparation of fruits and fruit juices, prior to LC/MS or other analytical chromatography. Recently, a nonregistered fungicide residue, carbendazim, was detected in orange juice purchased at a local market. This juice was produced from orange juice concentrate imported into the USA. In this application note, we discuss sample preparation strategies for determination of conazole fungicides, including carbendazim, in orange juice. First, we will focus on a sample preparation procedure using DisQuE products for QuEChERS suitable for many classes of pesticides and a wide variety of fruits, vegetables, and juices. Using UPLC/MS/MS, five conazole fungicides, including carbendazim, were easily detected at 10 μg/L (ppb) in the QuEChERS extract of orange juice. No further sample preparation was required. The QuEChERS extract can then be used as a precursor to further sample cleanup for targeted analysis of carbendazim and other conazole fungicides at ppb levels using LC with UV detection. Solid-phase extraction (SPE) with an Oasis MCX cartridge was used to reduce interference, and to concentrate the sample for this purpose. An incurred carbendazim sample was quantified at low ppb levels using LC with UV detection, applying this cleanup strategy. The Oasis MCX cleanup, although not required for the UPLC/MS/MS method, was shown to reduce matrix effects, and provide a cleaner extract. Thus, sample preparation using the DisQuE product for QuEChERS provides an extract suitable for direct analysis using UPLC/MS/MS and for HPLC/UV analysis, after enrichment and cleanup using mixed-mode SPE. WAT ERS SOLUT IONS Xevo TQ Mass Spectrometer