Simultaneous Determination of Amitraz and its Metabolites in Blood by Support Liquid Extraction Using UPHLC-QTOF.

This paper describes the use of UPHLC-QTOF for the analysis of pesticide amitraz and its metabolites in human blood. UPHLC-QTOF working in full scan mode simultaneously with a single MS/MS scan at 10 eV was employed to analyze in solid-support liquid-liquid extracts (SLE) of the human blood. Detection and quantification were carried out using full scan data (protonated molecules [M+H]+) while MS/MS data were used for fragment identification only. MS/MS scans were not found to have any negative influence on quantitation under the applied conditions. Verification studies were accomplished at low concentrations (1 ng/mL), and accuracy errors lower than 5 ppm were achieved. The human blood extracts spiked at LOQ and three QC fortification levels produced average recoveries in the range of 79.3-92.5% with relative standard deviations smaller than 10% for all analytes. Limits of detection (LODs) were between 0.1 and 0.5 ng/mL. Finally, the proposed method was successfully applied to a case of human poisoning.

Simultaneous Determination of Xylazine and 2,6-Xylidine in Blood and Urine by Auto Solid-Phase Extraction and Ultra High Performance Liquid Chromatography Coupled with Quadrupole-Time of Flight Mass Spectrometry.

Xylazine as veterinary medicine for sedation, but intoxication cases in humans were identified in the last few years. A highly sensitive method is required for analyzing xylazine and its metabolites in human blood and urine. This article presents an ultra high performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry (UHPLC-QTOF) study for simultaneous determination of xylazine and 2,6-dimethylaniline (DMA) in human blood and urine. The samples were extracted and cleaned up by Oasis MCX solid-phase extraction. The analysis is performed using an UHPLC-QTOF. Analysis precision, accuracy, sensitivity, linear range, limit of detection (LOD) and limit of quantification (LOQ) were validated for the proposed method. In the blood and urine samples, the linear calibration curves with high linearity are obtained over the range of 2.0-1,000.0 ng/mL. The LOD for xylazine and DMA in blood are 0.2 and 0.1 ng/mL, in urine are 0.4 and 0.2 ng/mL; the LOQ for xylazine and DMA in blood are 0.6 and 0.3 ng/mL, in urine are 1.0 and 0.6 ng/mL, respectively. The intra- and interday precision is better than 8.6 and 11.9%. In conclusion, the proposed method is highly sensitive and reproducible, thus suitable for accurate quantification of xylazine and its metabolites in blood and urine.

Synthesis of metal-semiconductor core-shell nanoparticles using electrochemical surface-limited reactions.

We report the synthesis of Au/CuI and Au/CdS core-shell nanoparticle (NP) thin films using codeposition and electrochemical atomic layer deposition (EC-ALD). Au nanoparticle films were prepared on glassy carbon supports by depositing alternating layers of poly(diallyl dimethylammonium)-stabilized Au nanoparticles and CoP(2)W(17)O(61)(8-) polyoxometallate interlayers. From there, CuI was deposited onto the surface of Au nanoparticles using electrochemical atomic layer deposition, while CdS films were grown by an atom-by-atom codeposition method. The semiconductor-Au core-shell nanoparticles were characterized by electrochemistry, photoluminescence spectroscopy, and Raman spectroscopy. Our results indicate that the semiconductors deposit onto the AuNP surface by surface limited electrochemical reactions.