A simple and high-throughput method to simultaneously determine selected benzodiazepines (i.e., diazepam, lorazepam, clonazepam, and bromazepam) in urine was developed and validated. The entire methodology consisted o...A simple and high-throughput method to simultaneously determine selected benzodiazepines (i.e., diazepam, lorazepam, clonazepam, and bromazepam) in urine was developed and validated. The entire methodology consisted of the application of an innovative extraction/cleanup procedure, namely liquid-liquid extraction with low-temperature partitioning (LLE-LTP), and analysis by liquid chromatography combined with high-resolution mass spectrometry (LC-HRMS). The LLE-LTP procedure was optimized via factorial design and by evaluating crucial variables, specifically the freezing mode (either slow or fast), the urine/acetonitrile volume ratio, and the sample ionic strength. The benzodiazepines were quantified using matrix-matched calibration curves where the following parameters were assessed by validation protocol: in general, linearity range of 17 - 200 μg?L–1 (r > 0.9957);limits of detection lower than 5 μg?L–1;relative standard deviations (RSD) lower than 12.5%;and accuracy ranging from 72.3 to 117%. To test this procedure’s performance, the method was applied to determine the content of diazepam in actual urine samples. The validation results obtained for the method demonstrated that the present methodology could be potentially applied in proficient laboratories as a routine approach for determining benzodiazepines compounds content in urine.展开更多
The degradation of ethinylestradiol (EE, an orally bio-active estrogen) in an aqueous-methanolic solution using a Ti/TiO2 thin-film electrode and UV radiation (a photoelectrocatalytic system) was evaluated. Hence, HPL...The degradation of ethinylestradiol (EE, an orally bio-active estrogen) in an aqueous-methanolic solution using a Ti/TiO2 thin-film electrode and UV radiation (a photoelectrocatalytic system) was evaluated. Hence, HPLC/UV analysis shows that EE (at 0.34 mmol) is totally consumed after 30 minutes of exposure to the photoelectrocatalytic system in the presence of Na2SO4 (0.1 mol·L-1) and with an applied bias potential of +1.0 V versus the Ag/AgCl reference electrode. Moreover, monitoring by direct infusion electrospray ionization mass spectrometry (ESI-MS) and SPME-GC/ MS (solid phase microextraction coupled with gas chromatography-mass spectrometry) reveals that apparently no degradation products are formed under these conditions. Hence, this study demonstrates that the photoelectrocatalytic system can be efficiently used to promote the complete degradation (and likely mineralization) of this hormone under these conditions.展开更多
基金Conselho Nacional de Desenvolvimento Cientifico e Tecnologico(CNPq)and Fundacao de Amparo a Pesquisa do Estado de Minas Gerais(FAPEMIG)for financial support and research fellowships.
文摘A simple and high-throughput method to simultaneously determine selected benzodiazepines (i.e., diazepam, lorazepam, clonazepam, and bromazepam) in urine was developed and validated. The entire methodology consisted of the application of an innovative extraction/cleanup procedure, namely liquid-liquid extraction with low-temperature partitioning (LLE-LTP), and analysis by liquid chromatography combined with high-resolution mass spectrometry (LC-HRMS). The LLE-LTP procedure was optimized via factorial design and by evaluating crucial variables, specifically the freezing mode (either slow or fast), the urine/acetonitrile volume ratio, and the sample ionic strength. The benzodiazepines were quantified using matrix-matched calibration curves where the following parameters were assessed by validation protocol: in general, linearity range of 17 - 200 μg?L–1 (r > 0.9957);limits of detection lower than 5 μg?L–1;relative standard deviations (RSD) lower than 12.5%;and accuracy ranging from 72.3 to 117%. To test this procedure’s performance, the method was applied to determine the content of diazepam in actual urine samples. The validation results obtained for the method demonstrated that the present methodology could be potentially applied in proficient laboratories as a routine approach for determining benzodiazepines compounds content in urine.
文摘The degradation of ethinylestradiol (EE, an orally bio-active estrogen) in an aqueous-methanolic solution using a Ti/TiO2 thin-film electrode and UV radiation (a photoelectrocatalytic system) was evaluated. Hence, HPLC/UV analysis shows that EE (at 0.34 mmol) is totally consumed after 30 minutes of exposure to the photoelectrocatalytic system in the presence of Na2SO4 (0.1 mol·L-1) and with an applied bias potential of +1.0 V versus the Ag/AgCl reference electrode. Moreover, monitoring by direct infusion electrospray ionization mass spectrometry (ESI-MS) and SPME-GC/ MS (solid phase microextraction coupled with gas chromatography-mass spectrometry) reveals that apparently no degradation products are formed under these conditions. Hence, this study demonstrates that the photoelectrocatalytic system can be efficiently used to promote the complete degradation (and likely mineralization) of this hormone under these conditions.
