5papers in this issue.
A simple, specific, and economical LC–MS/MS method was investigated for the screening of 43 prescribed antihy-pertensive and related drugs in human urine. The urine samples were simply prepared by diluting and mixing with internal stan-dard before directly introduced to the LC-MS/MS system, which is fast, straightforward, and cost-effective. Fractional factorial, Box-Behnken, and I-optimal design were applied to screen and optimize the mass spectrometric and chromatographic factors. The analysis was carried out on a triple quadrupole mass spectrometer system utilizing multiple reaction monitoring with posi-tive and negative electrospray ionization method. Chromatographic separation was performed on a Thermo Scientific Accucore RP-MS column (50 × 3.0 mm ID., 2.6 µm) using two separate gradient elution programs established with the same mobile phases. Chromatographic separation was performed within 12 min. The optimal method was validated based on FDA guideline. The results indicated that the assay was specific, reproducible, and sensitive with the limit of detection from 0.1 to 50.0 µg/L. The method was linear for all analytes with coefficient of determination ranging from 0.9870 to 0.9981. The intra-assay preci-sion was from 1.44 to 19.87% and the inter-assay precision was between 2.69 and 18.54% with the recovery rate ranges from 84.54 to 119.78% for all drugs measured. All analytes in urine samples were stable for 24 h at 25 o C, and for 2 weeks at -60 o C. The developed method improves on currently existing methods by including larger number of cardiovascular medications and better sensitivity of 12 analytes.
Nitarsone is an organoarsenic antiprotozoal drug widely used to treat blackhead disease in turkeys and chickens. However, since its biological conversion into inorganic arsenic, a carcinogen was known, its residue in foods should be regu-lated. Thus, here, a novel method to determine residual nitarsone in various food commodities (pork, milk, egg, halibut, eel, and shrimp) using QuEChERS and LC-MRM was developed. The developed method was successfully validated through specificity, linearity (coefficient of determination, at least 0.991), recovery (R, 63.6 - 85.6%), precision (the relative standard deviation of R, 0.5 - 10.6%), and sensitivity (the lower limit of quantitation, 5 ppb) by following the Ministry of food and drug safety (MFDS) guidelines. The present method is the first mean to quantitate nitarsone using LC-MRM, and it was designed to be conveniently merged into a new method to quantitate multiple veterinary drugs for the positive list system (PLS). Therefore, the present method could contribute to fortify the food safety system in South Korea.
We aimed to compare the content of ginsenosides and the pharmacokinetics after the oral administration of four dif-ferent ginseng products at a dose of 1 g/kg in rats. The four different ginseng products were fresh ginseng extract, red ginseng extract, white ginseng extract, and saponin enriched white ginseng extract prepared from the radix of Panax ginseng C.A. Meyer. The ginsenoside concentrations in the ginseng product and the rat plasma samples were determined using a liquid chromatogra-phy-tandem mass spectrometry (LC-MS/MS). Eight or nine ginsenosides of the 15 tested ginsenosides were detected; however, the content and total ginsenosides varied depending on the preparation method. Moreover, the content of triglycosylated ginse- nosides was higher than that of diglycosylated ginsenosides, and deglycosylated ginsenosides were not present in any prepara-tion. After the single oral administrations of four different ginseng products in rats, only four ginsenosides, such as 20(S)-ginsenosides Rb1 (GRb1), GRb2, GRc, and GRd, were detected in the rat plasma samples among the 15 ginsenosides tested. The plasma concentrations of GRb1, GRb2, GRc, and GRd were different depends on the preparation method but pharmacoki-netic features of the four ginseng products were similar. In conclusion, a good correlation between the area under the concentra-tion curve and the content of GRb1, GRb2, and GRc, but not GRd, in the ginseng products was identified and it might be the result of their higher content and intestinal biotransformation of the ginseng product.
We aimed to develop and validate a sensitive analytical method of nannozinone A, active metabolite of Nannochelins A extracted from the Myxobacterium Nannocytis pusilla, in mouse plasma using a liquid chromatography-tandem mass spec-trometry (LC-MS/MS). Mouse plasma samples containing nannozinone A and 13 C-caffeine (internal standard) were extracted using a liquid-liquid extraction (LLE) method with methyl tert-butyl ether. Standard calibration curves were linear in the concen-tration range of 1 - 1000 ng/mL (r 2 > 0.998) with the inter- and intra-day accuracy and precision results less than 15%. LLE method gave results in the high and reproducible extraction recovery in the range of 78.00–81.08% with limited matrix effect in the range of 70.56-96.49%. The pharmacokinetics of nannozinone A after intravenous injection (5 mg/kg) and oral administra- tion (30 mg/kg) of nannozinone A were investigated using the validated LC-MS/MS analysis of nannozinone A. The absolute oral bioavailability of nannozinone A was 8.82%. Plasma concentration of nannozinone A after the intravenous injection sharply decreased for 4 h but plasma concentration of orally administered nannozinone A showed fast distribution and slow elimination for 24 h. In conclusion, we successfully applied this newly developed sensitive LC-MS/MS analytical method of nannozinone A to the pharmacokinetic evaluation of this compound. This method can be useful for further studies on the pharmacokinetic opti-mization and evaluating the druggability of nannozinone A including its efficacy and toxicity.
The impurity concentration is a crucial parameter for semiconductor thin films. Evaluating the impurity distribution in silicon thin film is another challenge. In this study, we have investigated the doping concentration of boron in silicon thin film using time of flight secondary ion mass spectrometry in dynamic mode of operation. Boron doped silicon film was grown on i) p-type silicon wafer and ii) borosilicate glass using hot wire chemical vapor deposition technique for possible applications in optoelectronic devices. Using well-tuned SIMS measurement recipe, we have detected the boron counts 10 1 ~10 4 along with the silicon matrix element. The secondary ion beam sputtering area, sputtering duration and mass analyser analysing duration were used as key variables for the tuning of the recipe. The quantitative analysis of counts to concentration conversion was done fol-lowing standard relative sensitivity factor. The concentration of boron in silicon was determined 10 17 ~10 21 atoms/cm 3 . The tech-nique will be useful for evaluating distributions of various dopants (arsenic, phosphorous, bismuth etc.) in silicon thin film efficiently.