Limit=250 words To accurately estimate exposure of bees to pesticides, analytical methods are needed to enable quantification of ng/g (ppb) levels of contaminants in small samples of pollen or the individual insects. A modified QuEChERS extraction method coupled with ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) analysis was tested to quantify residues of 1...

QuEChERS sample preparation was optimized using solvent extraction with acetonitrile and dispersive-solid phase extraction with primary and secondary amine sorbents, and validated for high-performance liquid chromatographic determination of nine steroids commonly used to adulterate herbal medicines: such as triamcinolone, prednisolone, hydrocortisone, methylprednisolone, betamethasone, dexameth...

The extensive use of pesticides in agriculture plays an important role in bees die-off and allows the presence of residues in hive products, particularly in honey. An accurate and reliable analytical method, based on QuEChERS extractive technique, has been developed for the quantitative determination by high-performance liquid chromatography UV-visible detector of 5 pesticides (Deltamethrin, Di...

Varietal thiols are important contributors to the aroma profile of a wide range beverages including beer. A methodology for simultaneous extraction and subsequent analysis varietal 3-sulfanylhexan-1-ol (3SH), 3-sulfanylhexylacetate (3SHA) 4-methyl-4-sulfanylpentan-2-one (4MSP), non-volatile precursors 3-S-cysteinylhexan-1-ol (Cys-3SH) 3-S-glutathionylhexan-1-ol (GSH-3SH) in beer was developed v...

A higher monitoring rate is highly desirable in the labs, but this goal is typically limited by sample throughput. In this study, we sought to assess the real-world applicability of fast, low-pressure GC-time-of-flight MS (LP-GC/TOFMS) for the identification and quantification of 150 pesticides in tomato, strawberry, potato, orange, and lettuce samples. Buffered and unbuffered versions of QuECh...

the most used quechers and gas chromatography methods were performed, to evaluate the presence of organochlorines, organophosphate, polychlorinated biphenyl and chlorobenzenes in water and in fish. according to the standard iso iec 17025, a recovery rate obtained ranged from 70 to 120% assessing the reliability of analysis results. the exceed rate in fish of malathion is 22.2, and 5.2 ppm in sa...

Optimized Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) pretreatment methods for determination of six polychlorinated biphenyls (PCBs) residues in fish and aquatic invertebrates samples were investigated. Large volume injection (LVI) coupled gas chromatography tandem mass spectrometry (GC-MS/MS) with selected reaction monitoring (SRM) was used to provide a very sensitive and select...

A rapid multi-residue method was developed for the determination of 20 organophosphorous pesticide residues in leeks by gas chromatography coupled to triple quadrupole mass spectrometry (GC–QqQMS/MS). The method was based on the modified QuEChERS sample preparation method. After microwave pre-treatment, leek samples were extracted with acetonitrile containing acetic acid 0.1% and cleaned by dis...

A method using QuEChERS sample preparation and an Agilent 6490 Triple Quadrupole LC/MS has been developed that provides rapid and sub-parts per billion (ppb) detection of synthetic yohimbine and yohimbe bark extract in dietary supplements. Using the chromatographic separation of the diastereomers of yohimbine, the synthetic compound can be distinguished from the tree bark extract. An Agilent 65...