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21.
Chromatographia - A novel, dual gradient LC method for quantification of vardenafil (VR) and its degradant products was developed with a multivariate approach. In the QbD approach, primary... 相似文献
22.
Kothari NC 《Talanta》1971,18(12):1242-1245
The emission spectrograph is used to determine thoria in monazite sand. A sample of only 15 mg is required and yields rapid and accurate results for 2% thoria or less. Of various additives tested as carriers, carbon and MoO3 were found to be best. A current of 6 A gave a proper rate of volatilization without excessive spattering. The 267.28 nm Mo line was used as internal standard and the 269.24 nm Th line for analysis. Silica and iron sulphide were used as matrix in synthetic samples. Results compared well with those obtained by wet-analysis. 相似文献
23.
The determination of lithium and nitrogen in a variety of materials by thermal neutron activation is described. The nuclear reactions used are 14N(n,p)14C and 6 Li(n,α)3H. Radionuclides. 14C and 3H for counting are isolated by fusion of the irradiated sample in a vacuum system. Data are presented on lithium and nitrogen concentrations in several terrestrial standards. The new method allows reliable measurements on 10–50-mg samples. 相似文献
24.
The oxidation of formic and oxalic acids by benzyltrimethylammonium dichloroiodate (BTMACI), in the presence of zinc chloride,
leads to the formation of carbon dioxide. The reaction is first order with respect to BTMACI, zinc chloride and organic acid.
Oxidation of deuteriated formic acid indicates the presence of a kinetic isotope effect. Addition of benzyltrimethylammonium
chloride enhances the rate. It is proposed that the reactive oxidizing species is [(PhCH2Me3N)+ (IZn2Cl6)-]. Suitable mechanisms have been proposed. 相似文献
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28.
The standardisation of a direct radioimmunoassay for progesterone using an125I labeled progesterone prepared by iodinating the tyrosine methyl ester (TME) conjugated to a progesterone hemiphthalate derivative
and an antibody prepared using progesterone linked to bovine serum albumin through 11α hemisuccinate derivative is described.
The hemiphthalate derivative of progesterone was prepared by reacting 11α-hydroxy progesterone with phthalic anhydride which
was then conjugated to TME by using isobutyl chloroformate. The conjugate was iodinated with125I using chloramine-T as oxidising agent and purified by thin layer chromatography. Radiochemical purity of the tracer was
>95% in all batches. The tracer gave 70–75% binding with excess antibody. Assays were optimised with 8-anilino-1-naphthalene
sulphonic acid (ANS) and sodium salicylate as blocking agents to release the progesterone from binding proteins. The assay
optimised with sodium salicylate as blocking agent has a sensitivity of 0.25 ng/ml and a working range of 0.25–50 ng/ml, whereas
the assay with ANS has a sensitivity of 0.75 ng/ml and a working range of 0.75–100 ng/ml. Serum samples were analysed and
compared with the values obtained with a homologous bridge assay. 相似文献
29.
H Martinez-Valdez R M Kothari H V Hershey M W Taylor 《Journal of chromatography. A》1982,247(2):307-314
A rapid and reliable protocol for the simultaneous separation of ribo-, deoxyribo- and cyclic nucleotides has been developed using high-performance liquid chromatography on a C18 microBondapak column and isocratic elution with ammonium phosphate buffer 0.2 m, pH 5.1). Resolution of deoxyribonucleotides has been confirmed by performing resolution before and after periodate oxidation. The general order of elution is ribonucleotides, deoxyribonucleotides and cyclic nucleotides. While periodate oxidation improved the clarity of separation of deoxyribonucleotides by eliminating ribonucleotides, incorporation of methanol in the eluent shortened the retention time of cyclic nucleotides. The application of this method to a complex biological system is reported. 相似文献
30.
The oxidation of substituted benzyl alcohols by bis(2,2′-bipyridyl) copper(II) permanganate (BBCP), leading to the corresponding benzaldehydes is first-order with respect to BBCP. Michaelis-Menten type kinetics were observed with respect to the alcohols. The oxidation of a,a-dideuteriobenzyl alcohol indicated the presence of a substantial kinetic isotope effect. The rates of oxidation of meta- and para-substituted benzyl alcohols were correlated in terms of Charton's triparametric LDR equation whereas ortho- substituted benzyl alcohols were correlated with a four parametric LDRS equation. The results of correlation analyses point to an electron-deficient reaction center in the transition state. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 9–16, 1997. 相似文献