Evaluation of direct analysis in real time for the determination of highly polar pesticides in lettuce and celery using modified Quick Polar Pesticides Extraction method.

Direct analysis in real time (DART) was evaluated for the determination of a number of highly polar pesticides using the Quick Polar Pesticides Extraction (QuPPe) method. DART was hyphenated to high resolution mass spectrometry (HRMS) in order to get the required selectivity that allows the determination of these compounds in complex samples such as lettuce and celery. Experimental parameters such as desorption temperature, scanning speed, and distances between the DART ion source and MS inlet were optimized. Two different mass analyzers (Orbitrap and QTOF) and two accessories for sample introduction (Dip-it® tips and QuickStrip™ sample cards) were evaluated. An extra clean-up step using primary-secondary amine (PSA) was included in the QuPPe method to improve sensitivity. The main limitation found was in-source fragmentation, nevertheless QuPPe-DART-HRMS proved to be a fast and reliable tool with quantitative capabilities for at least seven compounds: amitrole, cyromazine, propamocarb, melamine, diethanolamine, triethanolamine and 1,2,4-triazole. The limits of detection ranged from 20 to 60µg/kg. Recoveries for fortified samples ranged from 71 to 115%, with relative standard deviations <18%.

Study of the depletion of lincomycin residues in honey extracted from treated honeybee (Apis mellifera L.) colonies and the effect of the shook swarm procedure.

Bee colonies were treated with 1.2g lincomycin hydrochloride per hive (single treatment in sucrose solution) and samples of honey were then collected at intervals over a 41-week period. The samples were analysed for lincomycin using Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS). The highest mean concentration of lincomycin (pooled analytical results for brood and super honey) was 24 microugg(-1) 3 days after treatment, a mean of 3.5 microgg(-1) after 129 days. The shook swarm procedure was investigated and resulted in a lincomycin concentration of 34 microgg(-1) in honey (pooled results for brood and super honey) 3 days after treatment, declining to 0.38 microgg(-1) 129 days after treatment. Lincomycin was persistent in the hive and detected in all over winter (290 days after dosing) samples of honey collected from both non-shook swarmed and shook swarmed colonies. The results overall indicate that lincomycin parent is a suitable marker compound to detect lincomycin misuse in apiculture.