Sensitive method for simultaneous determination of TBBPA and its ten derivatives.

Tetrabromobisphenol A (TBBPA) and its derivatives are regarded as new contaminants, raising much attention on their environmental occurrence and fates. However, the sensitive detection of TBBPA and its main derivatives is still a great challenge. This study investigated a sensitive method for simultaneous detection of TBBPA and its ten derivatives using high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (HPLC-MS/MS) with atmospheric pressure chemical ionization (APCI) source. The method exhibited much better performance than previously reported methods. Furthermore, it was successfully applied in determining complicated environmental samples, including sewage sludge, river water and vegetable samples with concentration range from undetected (n.d.) to 25.8 ng g-1 dry weight (dw). For sewage sludge, river water and vegetable samples, the spiking recoveries of TBBPA and its derivatives ranged from 69.6 ± 7.0% to 86.1 ± 12.9%, 69.5 ± 13.9% to 87.5 ± 6.6%, and 68.2 ± 5.6% to 80.2 ± 8.3%, respectively; the accuracy ranged from 94.9 ± 4.6% to 113 ± 5%, 91.9 ± 10.9% to 112 ± 7%, and 92.1 ± 5.1% to 106 ± 6%, and the method quantitative limits ranged from 0.00801 to 0.224 ng g-1 dw, 0.0104-0.253 ng L-1, and 0.00524-0.152 ng g-1 dw, respectively. Moreover, the present manuscript describes for the first time the simultaneous detection of TBBPA and ten derivatives from various environmental samples, providing fundamental work for further research on their environmental occurrences, behaviors and fates.

A LC-MS/MS method with electrospray ionization and atmospheric pressure chemical ionization source for analysis of pesticides in hemp.

BACKGROUND: Pesticide testing for hemp has traditionally focused on techniques like QuEChERS with dSPE and SPE which demand time-consuming sample preparation, typically resulting in poor recovery rates for some pesticides, and requires the use of both LC-MS/MS and GC-MS/MS based instruments to cover the analysis for all regulated pesticides. In this study, we describe a streamlined approach for working with LC-MS/MS featuring a dual electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) sources using solvent extraction for faster and easier sample preparation and with 80-120% recovery for the analysis of all of 66 pesticides (regulated by California state in cannabis) with low detection limits in hemp. METHODS: A simple solvent extraction with acetonitrile was used to extract pesticides from hemp. A LC-MS/MS system with dual ESI and APCI source was used to determine sensitivity for the analysis of 66 pesticides in hemp matrix, 62 pesticides were analyzed using an 18-min LC-MS/MS method with an ESI source and the other 4 pesticides were measured using a 6-min LC-MS/MS method with an APCI source. RESULTS: The limit of quantitation (LOQ) of all 66 pesticides in hemp was in the range of 0.0025-0.1 µg/g which was well below the California state action limits of these analytes in cannabis products. A simple, fast, and cost-effective solvent extraction method was used for sample preparation to get good recovery in the range of 80-120% with RSD less than 20%. The unique ionization mechanism of chlorinated pesticides such as pentachloronitrobenzene using the LC-MS/MS system with an APCI source was elucidated. The proficiency test report generated with the LC-MS/MS method showed acceptable results for all of 66 pesticides in hemp with all of th z scores less than 2 with no false positives and negatives. The stability data collected over 5 days showed RSD less than 20% for 66 pesticides in hemp, and this demonstrated the robustness of the LC-MS/MS system used in this work. CONCLUSIONS: A LC-MS/MS method with dual ESI and APCI sources was developed for the analysis of 66 pesticides in hemp. The recovery of all pesticides from a hemp matrix was in the acceptable range of 80-120% with RSD less than 20%.

Identification of very long-chain (>C24) fatty acid methyl esters using gas chromatography coupled to quadrupole/time-of-flight mass spectrometry with atmospheric pressure chemical ionization source.

Gas chromatography coupled to a quadrupole time-of-flight mass analyzer (QTOF) with an atmospheric pressure chemical ionization (APCI) source has been tested to study the ionization and mass spectrometric behavior of long-chain and very long-chain polyunsaturated fatty acids (LC-PUFAs, C18-24; VLC-PUFAs, >C24). The protonated molecule ([M+H]+), measured at accurate mass, became the base peak of the spectrum for all the studied compounds and was promoted by the addition of water into the source. This fact overcame the existing difficulties for the identification of VLC-PUFAs when using an electron ionization source (EI). The extensive fragmentation of PUFAs in this source is the main drawback due to the fact that since reference standards are not commercially available, final identification relies on retention time estimation. The application of GC-APCI-QTOF to the screening of lipid extracts from the eyes of different fish species added confidence to the identification of several VLC-PUFAs. Further investigation of ion ratios allowed to predict the position of key double bonds enabling the classification of VLC-PUFAs as ω3 or ω6 compounds. VLC-PUFAs spectra found in biological samples were compared to those obtained from corresponding peaks found in heterologous expression experiments of fish's Elovl4.