Derivatization of chiral carboxylic acids with (S)‐anabasine for increasing detectability and enantiomeric separation in LC/ESI‐MS/MS

A simple and practical derivatization procedure for increasing the detectability and enantiomeric separation of chiral carboxylic acids in LC/ESI‐MS/MS has been developed. (S)‐Anabasine (ANA) was used as the derivatization reagent and rapidly reacted with carboxylic acids [3‐hydroxypalmitic acid (3‐OH‐PA), 2‐(β‐carboxyethyl)‐6‐hydroxy‐2,7,8‐trimethylchroman (γ‐CEHC), and etodolac] in the presence of 4‐(4,6‐dimethoxy‐1,3,5‐triazin‐2‐yl)‐4‐methylmorpholium chloride. The resulting ANA‐derivatives were highly responsive in ESI‐MS operating in the positive‐ion mode and gave characteristic product ions during MS/MS, which enabled sensitive detection using selected reaction monitoring; the detection responses of the ANA‐derivatives were increased by 20–160‐fold over those of the intact carboxylic acids and the limits of detection were in the low femtomole range (1.8–11 fmol on the column). The ANA‐derivatization was also effective for the enatiomeric separation of the chiral carboxylic acids; the resolution was 1.92, 1.75, and 2.03 for 3‐OH‐PA, γ‐CHEC, and etodolac, respectively. The derivatization procedure was successfully applied to a biological sample analysis; the derivatization followed by LC/ESI‐MS/MS enabled the separation and detection of trace amounts of 3‐OH‐PA in neonatal dried blood spot and γ‐CEHC in human saliva with a simple pretreatment and small sample volume.     

Generation of multi-color stimulated raman emission from two-color linearly or circularly polarized pump beams

A laser beam at two different frequencies separated by 587 cm^–1 is focused into pressurized hydrogen (rotational transition energy, 587 cm^–1) to generate multi-color stimulated Raman emission. The polarization state and the pulse energy are measured for each generated emission line using linearly and circularly polarized pump beams. The effect of the polarization is discussed by using a parameter characterizing the polarizability of hydrogen and a conservation rule for the angular momentum in four-wave mixing. Many rotational lines are generated with linearly polarized pump beams through a four-wave mixing process. This is in striking contrast to the results obtained by using a single-color circularly polarized pump beam which generates only one rotational line through a conventional stimulated Raman process.     

Coadsorption of NO and other small gases (H2 and CO) on polycrystalline rhodium surface

The coadsorption of NO and other small gases (H₂ and CO) on a polycrystalline Rh filament has been studied by thermal desorption mass spectroscopy, using ¹⁵NO. The sample was exposed to a mixture of nitric oxide and other gases with various concentrations of ¹⁵NO at room temperature. It is indicated that NO, CO and H₂ coadsorbs on the rhodium surface, and NO desorbs as N₂ and O₂. NO is adsorbed mainly in the dissociation at lower coverage and molecular adsorption becomes dominant at higher coverage. But the amount of desorbed O₂ was very small. The chemisorption of CO is affected by the chemisorbed NO. Thermal desorption of hydrogen is detected when the value of P_15NO/P_CO is very small. The hydrogen adsorbed on the rhodium surface is replaced by NO with a longer exposure time.     

Theory of spinodal decomposition in critical fluid mixtures

The fluctuation spectrum in spinodally decomposing critical fluid mixtures is studied theoretically focusing on the effects of long range hydrodynamic interaction. Agreements with the observed peak position and peak height of the fluctuation spectrum are excellent and fair, respectively.     

Spectrographic determination of ultramicro amounts of boron in high-purity silicon tetrachloride and trichlorosilane

A new sensitive method is proposed for the determination of boron in highpurity silicon tetra chloride and trichlorosilane. The method consists of complexing boron with triphenylchloromethane, removal of excess silicon tetrachloride, hydrolysis of the complex, and improved spectrographic excitation of liberated boric acid.The best sensitivity attainable is 0.03μg B, which corresponds to 0.06 p.p.b. B for a 500-g sample.     

Determination of plasma and urinary cortisol by high-performance liquid chromatography using fluorescence derivatization with dansyl hydrazine

A method is described for the determination of cortisol in human plasma and urine by high-performance liquid chromatography using fluorophotometric detection. After extraction with methylene chloride, cortisol is labelled with dansyl hydrazine, and then separated by high-performance chromatography. The eluate is monitored by a fluorophotometer at 350 nm (excitation) and 505 nm (emission). The optimum conditions for the determination, such as HCl and dansyl hydrazine concentrations, reaction time and reaction temperature, and for the eluent of high-performance liquid chromatography, are discussed. Linearity of the fluorescence intensity (peak height) with the amount of cortisol was obtained between 0.5 and 60 ng. The recoveries for 50 and 100 ng of added cortisol were 98.7 and 95.4% for plasma, and 96.4 and 90.6% for urine, respectively. Comparison with a radioimmunoassay gave a correlation coefficient of 0.978. The proposed method is suitable for the routine analysis of cortisol in plasma and urine.     

Observation of B+-->K1(1270)+gamma

We report the observation of the radiative decay B+-->K1(1270)(+) gamma using a data sample of 140 fb(-1) taken at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- collider. We find the branching fraction to be B(B+-->K1(1270)(+)gamma)=(4.3+/-0.9(stat.)+/-0.9(syst.))x10(-5) with a significance of 7.3sigma. We find no significant signal for B+-->K1(1400)(+)gamma and set an upper limit B(B+-->K1(1400)(+)gamma)<1.5 x 10(-5) at the 90% confidence level. We also measure inclusive branching fractions for B+-->K+pi+pi-gamma and B0-->K0pi+pi-gamma in the mass range 1 GeV/c(2)相似文献