scholarly journals Comparison of buffers and detection systems for high-pressure liquid chromatography of peptide mixtures

1981 ◽  
Vol 199 (1) ◽  
pp. 43-51 ◽  
Author(s):  
K J Wilson ◽  
A Honegger ◽  
G J Hughes
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Fluorescence Detection ◽  
Low Ph ◽  
Ease Of Use ◽  
Reverse Phase ◽  
Detection Systems ◽  
The Third ◽  
Hydrophobic Peptides ◽  
Peptide Mixtures

The chromatographic properties of peptides ranging in length from 2 to 65 residues have been compared on reverse-phase packings in three buffer systems at low pH. Of the buffers examined, two are widely used in connection with u.v. detection [(i) phosphate/acetonitrile or (ii) phosphate/propan-2-ol] and the third for fluorescence detection [(iii) pyridine/formate-pyridine/acetate/propan-1-ol]. The addition of a chaotropic salt, NaClO4, to the phosphate buffers, as first described by Meek (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 1632-1636, is shown to significantly improve the chromatographic behaviour of more hydrophobic peptides. The two most commonly used detection systems, u.v. and fluorescence, are compared in terms of ease of use and sensitivity.

Determination of Zearalenone in Corn by High Pressure Liquid Chromatography and Fluorescence Detection

1978 ◽  
Vol 61 (5) ◽  
pp. 1058-1062
Author(s):  
George M Ware ◽  
Charles W Thorpe
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Fluorescence Detection ◽  
Hplc Analysis ◽  
Fluorescence Detector ◽  
Reverse Phase

Abstract A method is reported for determining zearalenone in corn at levels as low as 10 ng/g. Samples are extracted with chloroform-water and cleaned up by liquid-liquid chromatography, and the zearalenone is detected by a fluorescence detector after separation by reverse phase high pressure liquid chromatography (HPLC). Recoveries of zearalenone added to corn at levels from 10 to 200 ng/g averaged greater than 89%. In addition, a confirmation procedure is described which involves sequential HPLC analysis of the sample and a zearalenone standard, using 4 different excitation wavelengths and comparing fluorescence responses obtained. This method was successfully applied to the analysis of 11 samples of cornmeal; zearalenone was detected in 9 of the samples at levels from 11 to 69 ng/g.

Determination of Diacetyl in Butter as 2,3-Diaminonaphthalene Derivative, Using a Fluorometric Procedure or Reverse Phase Liquid Chromatography with Fluorescence Detection

1988 ◽  
Vol 71 (3) ◽  
pp. 462-465
Author(s):  
Pietro Damiani ◽  
Giovanni Burini
Keyword(s):  
Liquid Chromatography ◽  
Fluorescence Detection ◽  
The Other ◽  
Reverse Phase ◽  
Reverse Phase Liquid Chromatography ◽  
Fluorescence Characteristics ◽  
Chromatographic Procedure ◽  
Phase Liquid ◽  
Liquid Chromatographic

Abstract Two procedures, one fluorometric and the other reverse phase liquid chromatographic, for determination of a derivative of diacetyl are described. Exploratory work on diacetyl standard solutions to establish the best conditions for the derivatization with 2,3-diaminonaphthalene (DAN) to yield 2,3-dimethylbenzo[g]-quinoxaline (DMBQ) is discussed, as well as the fluorescence characteristics of the DMBQ derivative. Diacetyl was determined in 10 commercial butter samples by the proposed procedures and by other known methods (determination of o-phenylenediamine and 3,3-diaminobenzidinederivatives). Recoveries from butter samples spiked with known amounts of diacetyl ranged from 96.9 to 101.8% (with CVs ranging from 0.3 to 2.1%) for the fluorometric procedure and from 96.9 to 102.7% (with CVs ranging from 0.5 to 2.4%) for the chromatographic procedure. These results agree well with those obtained with o-phenylenediamine and 3,3-diaminobenzidine methods on the same butter samples. The proposed methods have the advantages of improved detectability and specificity.

Screening Method for Vitamins A and D in Fortified Skim Milk, Chocolate Milk, and Vitamin D Liquid Concentrates

1979 ◽  
Vol 62 (6) ◽  
pp. 1358-1360
Author(s):  
Susan K Henderson ◽  
Lucia A Mclean
Keyword(s):  
Vitamin D ◽  
High Pressure ◽  
Liquid Chromatography ◽  
Vitamin A ◽  
Mobile Phase ◽  
Screening Method ◽  
Skim Milk ◽  
Chocolate Milk ◽  
Reverse Phase ◽  
Milk Chocolate

Abstract Vitamin A was determined in fortified chocolate milk and skim milk; vitamin D was determined in fortified chocolate milk, skim milk, and vitamin D concentrates, using reverse phase high pressure liquid chromatography (HPLC). The sample is saponified, extracted with hexane, and chromatographed in an HPLC system on a 10 μm Vydac TP reverse phase C18 column, using acetonitrile-methanol (9+1) as the mobile phase. For 6 replicates, the recoveries of vitamins A and D, using this procedure, were 99 and 98%, respectively.

Spontaneous decay of oxidized ascorbic acid (dehydro-L-ascorbic acid) evaluated by high-pressure liquid chromatography

1990 ◽  
Vol 36 (10) ◽  
pp. 1807-1809 ◽  
Author(s):  
A M Bode ◽  
L Cunningham ◽  
R C Rose
Keyword(s):  
High Pressure ◽  
Ascorbic Acid ◽  
Liquid Chromatography ◽  
Vitamin C ◽  
High Pressure Liquid Chromatography ◽  
Analytical Procedure ◽  
Low Ph ◽  
Experimental Conditions ◽  
Rate Of Decay ◽  
Reduced Forms

Abstract We applied high-pressure liquid chromatography to assess the decomposition of the oxidized form of vitamin C, dehydro-L-ascorbic acid. We selected experimental conditions that might represent a wide variety of clinical and research procedures. Decay of dehydro-L-ascorbic acid proceeded much more rapidly at high pH (7-8) than at low pH (3-5) and was more rapid at 37 or 45 degrees C than at 0 or 23 degrees C. When evaluated at pH 6.6, the percent decay was somewhat more rapid from an initial concentration of 1000 mumol/L than at 5-10 mumol/L. The analytical procedure (HPLC) provided useful information about the rate of decay under various conditions. This may facilitate future biological and clinical studies that require a distinction between the oxidized and reduced forms of vitamin C.

The Determination of Urinary Oxypurines as Markers of Gastrointestinal Tumors

1987 ◽  
Vol 73 (3) ◽  
pp. 289-294 ◽  
Author(s):  
Marco Lorenzi ◽  
Daniela Vannoni ◽  
Roberto Leoncini ◽  
Ranieri Caldarone ◽  
Enrico Marinello
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Urinary Excretion ◽  
Tumor Marker ◽  
Cancer Patients ◽  
Plasma Levels ◽  
Colorectal Tumor ◽  
Reverse Phase ◽  
Tumor Bearing

Plasma levels and urinary excretion of oxypurines – hypoxanthine and xanthine – were evaluated by reverse-phase high-pressure liquid chromatography in 13 patients affected by gastric tumors and in 19 colorectal tumor-bearing patients. Preliminary results indicate higher values of urinary xanthine and an increase in the xanthine/hypoxanthine ratio in cancer patients. The increase was not generalized to all subjects, and did not appear related either to the stage of the disease or to CEA values. The limits within which the determination of urinary oxypurines can be employed as a tumor marker are discussed.

Quantitation of the Contaminants in Technical Fenitrothion by Reverse Phase High Pressure Liquid Chromatography

1979 ◽  
Vol 62 (6) ◽  
pp. 1222-1230
Author(s):  
William P Cochrane ◽  
Monique Lanouette ◽  
Roy Greenhalgh
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
The Other ◽  
Average Level ◽  
Uv Detector ◽  
Reverse Phase ◽  
Technical Grade ◽  
Solvent Systems

Abstract Technical grade samples of fenitrothion were analyzed by high pressure liquid chromatography (HPLC) on a reverse phase LiChrosorb RP-8 column, using 3 solvent systems and a UV detector set at 269 nm. All commercial samples analyzed contained >94% fenitrothion; in addition, 9 contaminants were identified and quantitated. Bisfenitrothion was the major contaminant, with average amounts of 2.46% from one manufacturer and 1.17% from another. The second most abundant toxicant was S-methyl fenitrothion, which was present at an average level of 0.71% in one source but only 0.16% in the other. The amount of fenitrooxon was 0.046% or less in samples from 2 manufacturers. Other contaminants quantitated include the 2 demethyl fenitrothion isomers, 3-methyl-4-nitrophenol, 3-methyl-6-nitrophenol, 3-methyI-4-nitroanisole, and bis-S-methyl fenitrothion. The total amount of the constituents quantitated in 9 commercial samples was 99.07 ± 1.81%. By comparing the amounts of bis-fenitrothion and phenols present in technical grade fenitrothion, it should be possible to identify the specific manufacturers of the various products.

A Simple Procedure for the Determination of Carbamazepine in Plasma by High Pressure-Liquid Chromatography

1979 ◽  
Vol 16 (1-6) ◽  
pp. 213-216 ◽  
Author(s):  
C. K. Johnston ◽  
G. H. Lester
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Mobile Phase ◽  
Simple Procedure ◽  
Internal Standard ◽  
Reverse Phase ◽  
Coefficients Of Variation ◽  
Initial Results

We describe a simple, rapid procedure for the estimation of carbamazepine in plasma. Protein is precipitated, and extraction is achieved by the addition of acetonitrile containing the internal standard N-acetyltryptophan ethyl ester. Separation is by reverse-phase high-pressure liquid chromatography with an acetonitrile: water mobile phase, and detection is by UV absorption at 280 nm. Total retention time is less than 7 minutes. Initial results gave within-batch and between-batch coefficients of variation of less than 2 %, and mean recovery of 97 %. The method is free from interference by other common anticonvulsant drugs.

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