摘要:

A conventional analytical HPLC system is modified by the addition of a catalytic Nafion-H® reactor column placed between the injector and a typical analytical column. The reactor column promotes cyclization reactions and the analytical column separates the reactant and product(s). In the reactions attempted, the analytical column has given baseline separation of the reactant from the desired product(s). Recoveries, yields and purities are generally equal to or better than those obtained with conventional synthesis and workup techniques. The advantages of this system are the rapidity of the reaction, separation, and ease of workup. Product(s) are readily recovered from the low-boiling solvents used and intact reactant may be recovered and reinjected. Three functional groups leading to cyclization are presented and the effects of solvent composition, temperature and flow rate are discussed in detail for one reaction.

ISSN:0003-2719    

DOI:10.1080/00032718708064558

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A novel system for the determination of ammonia based on the chemiluminescent reaction between hypochlorite and luminol is presented. The technique of flow injection analysis was employed to automate the system. Ammonia reacts with hypochlorite to form monochloramine in basic solution which decreases the observed chemiluminescence intensity. Several interferents are identified, and the reasons why they interfere are discussed. The effects of interferents are Minimized through the use of a double-tube dialyzer where the ammonia is diffused across the dialyzer membrane into a recipient stream of hydrochloric acid.

ISSN:0003-2719    

DOI:10.1080/00032718708064559

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A rapid, simple and specific procedure for the simultaneous assay and determination of enantiomeric purity of pharmaceutical grade dextroamphetamine is described. The procedure is faster, more precise and more specific for the dextroisomer than the U.S.P. method.

ISSN:0003-2719    

DOI:10.1080/00032718708064560

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A procedure for simultaneous measurements of carbonate and oxalate contents in nonaqueous samples is presented. It is based on determination of the lead ion concentration by d.c. polarography. The determination of oxalate and carbonate is possible in the range of 0.1 mM up to 10 mM.

ISSN:0003-2719    

DOI:10.1080/00032718708064561

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A new method is described that facilitates determining the efficiency of air sampling traps to adsorb and thermally desorb volatile organic compounds. A known volume of a liquid standard of volatile organic compounds is vaporized into an air stream, a fraction of which is collected on an air sampling trap. This trap is subsequently thermally desorbed and analyzed using a GC/FID. The efficiency of the trap to adsorb and thermally desorb each compound tested is calculated.

ISSN:0003-2719    

DOI:10.1080/00032718708064562

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A simple TLC separation and semi-quantitative visual determination method was used to analyse the volatile phenols in the waste water of the petroleum industry and the grain irrigated by the waste water. The phenol in the rice irrigated by the water that contained phenol for artificial preparation was also studied. A preliminary conclusion was obtained, that the grain could absorb volatile phenols from irrigation water.

ISSN:0003-2719    

DOI:10.1080/00032718708064563

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A new sensitive, accurate and reproducible method has been developed for the assay of L-aspartase (aspartate ammonia-lyase, EC 4.3.1.1) activity. Ammonium ion selective elctrodes were used to measure the increase in activity of ammonium ion produced during the deamination of L-aspartate, a reaction catalyzed by L-aspartase. The sensitive electrode membrane was prepared by immobilizing nonactin in polyvinyl chloride (PVC). Our potentiometric studies indicate an optimum substrate concentration of 0.05 M for L-aspartate and an optimum pH of 8.4. Also, a linear calibration curve of the electrode response towards enzyme activity was obtained in which activity units as low as 0.007 units/ml were detected. These findings were confirmed using spectrophotometric techniques. The increase in absorbance at 240 nm was used to measure the increase in fumarate during the deamination of L-aspartate. The interference from potassium ion was eliminated by dialyzing the enzyme preparation against water.

ISSN:0003-2719    

DOI:10.1080/00032718708064564

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A method of cyclic voltammetry with adsorptive preconcentration is proposed, exploiting the differences in the behaviour of open circular or linear DNA and closed circular DNA under denaturing conditions. The height of the anodic peak of single-stranded DNA is inversely proportional to the content of closed circular DNA in the sample. The sensitivity and concentration range of the determination depends on the time of adsorptive preconcentration used. A linear dependence of the height of the anodic peak on the content of the DNA of the denatured plasmid ColE1 was observed in the concentration range 0.25 to 0.2 μg DNA/ml with 4 min adsorptive preconcentration. With double this time one could detect down to 0.05 μg DNA/ml. The determination of single-stranded DNA was unaffected by the presence of an excess of duplex DNA in the sample analysed. The method is fast and requires less than a microgram of plasmid DNA.

ISSN:0003-2719    

DOI:10.1080/00032718708064565

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A size exclusion chromatographic method is reported that quantitated PEG 3350 in human plasma and urine to a concentration of 10 μg/ml in plasma, or urine. The chromatographic system consisted of a 500 A gel permeation analytical column, a differential refractometer detector, and chloroform as the eluting solvent. Organic extraction was used as an initial separation technique. PEG 400 was used as the internal standard for PEG 3350, and showed similar extraction properties. Spiked plasma standards yielded standard calibration curves with correlation coefficients of greater than 0.99, and relative standard deviations (n=3) of 2.19% (500 μg/ml) and 6.97% (20 μg/ml). The analytical technique was used to estimate the elimination rate constant of PEG 3350 from 5 normal human subjects after oral administration of 240 grams of PEG 3350. KEwas found to be 0.1079 hr−10.03781−1hr (mean s.d.) using the Sigma-minus data analysis method on total urines collected from the 5 subjects at varying intervals.

ISSN:0003-2719    

DOI:10.1080/00032718708064566

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The composition of two glutaraldehyde solutions with different grades of purity was studied by HPLC, UV, J-H and13C NMR spectroscopy. The reactions between various amino acids and the two glutaraldehyde solutions were investigated by UV spectrophotometry. The impurities in the most impure glutaraldehyde solution could be characterized with UV giving a 235 nm absorption, with HPLC as two peaks with retention times 3.36 and 5.78 min and with13C NMR as small signals in the 102.7-94.9 ppm area. It is proposed that the two glutaraldehyde solutions give different reaction products with amino acids.

ISSN:0003-2719    

DOI:10.1080/00032718708064567

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor