Isotope ratio analysis of nuclear materials in individual particles is of great importance for nuclear safeguards. Although secondary ion mass spectrometry (SIMS) and thermal ionization mass spectrometry (TIMS) are utilized for the analysisof individual uranium particles, few studies were conducted for the analysis of individual uranium-plutonium mixed oxide particles. In this study, we applied SIMS and inductively coupled plasma mass spectrometry (ICP-MS) to the isotope ratio analysis of individualU-Pu mixed oxide particles. In the analysis of individual U-Pu particles prepared from mixed solution of uranium and plutoniumstandard reference materials, accurate 235U/238U, 240Pu/239Pu and 242Pu/239Pu isotope ratios were obtained with both methods. However, accurate analysis of 241Pu/239Pu isotope ratio was impossible, due to the interference of the 241Am peak to the 241Pupeak. In addition, it was indicated that the interference of the 238UH peak to the 239Pu peak has a possibility to prevent accurateanalysis of plutonium isotope ratios. These problems would be avoided by a combination of ICP-MS and chemical separation ofuranium, plutonium and americium in individual U-Pu particles.
The effectiveness of microwave-assisted protein digestion in different well positions of a 96-well microplate wasinvestigated where microwave-assisted protein digestion of bovine serum albumin was performed in 10 different wells of a 96-wellmicroplate in a microwave oven. Similarly increased sequence coverages (~70%) were generally observed for the 10 microwaveassistedprotein digestion samples compared to conventional overnight digestion (63%), which is possibly due to higher miscleavageratios (~53%) of the samples from microwave-assisted protein digestion than conventional overnight digestion (42.1%). The reproducibleresults of microwave-assisted digestions from different well positions demonstrate the potential of high-throughput analysis ofproteins using microwave-assisted protein digestion.
The pharmacokinetic properties of S-amlodipine were studied using racemic amlodipine and single S-enantiomer(SK310) administration to rats. Plasma levels of the drug were determined using chiral liquid chromatography coupled with tandemmass spectrometry following solid phase extraction. The stereospecific analysis of amlodipine was performed on an α-acidglycoprotein (AGP) column using a mobile phase comprising 10 mM ammonium acetate (pH 4.0) and propanol at a flow rate of0.2 mL/min. This method was used to perform a comparative study of the pharmacokinetics of amlodipine and SK310. Theresults revealed that the pharmacokinetic profile of S-amlodipine after the administration of SK310 was comparable to thatfollowing the administration of the racemic mixture.
Pyrophosphates are the key intermediates in the biosynthesis of isoprenoids, and their concentrations could revealthe benefits of statins in cardiovascular diseases. Quantitative analysis of five pyrophosphates, including isopentenyl pyrophosphate(IPP), dimethylallyl pyrophosphate (DMAPP), geranyl pyrophosphate (GPP), farnesyl pyrophosphate (FPP), and geranylgeranylpyrophosphate (GGPP), was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in negative ionizationmode. After dilution with methanol, samples were separated on a 3 μm particle multi-modal C18 column (50 × 2 mm)and quantified within 10 min. The gradient elution consists of 10 mM ammonium bicarbonate and 0.5% triethylamine (TEA) inwater and 0.1% TEA in 80% acetonitrile was used at the flow rate of 0.4 mL/min. Overall recoveries were 51.4-106.6%, whilethe limit of quantification was 0.05 μg/mL for GPP and FPP and 0.1 μg/mL for IPP, DMAPP, and GGPP. The precision (% CV)and accuracy (% bias) of the assay were 1.9-12.3% and 89.6-111.8%, respectively, in 0.05-10 μg/mL calibration ranges (R2 > 0.993). The devised LC-MS/MS technique with the multi-modal C18 column can be used to estimate the biological activity of pyrophosphatesin plasma and may be applicable to cardiovascular events with cholesterol metabolism as well as the drug efficacy of statins.