Overcoming Retention Time Shifts as a Source of Error in HPLC Analysis

Konstantinides, Frank N.; Garr, Leonard; Li, John C.; Cerra, Frank B.

doi:10.1093/chromsci/25.4.158

Cited by 11 publications

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“…Problems with shifts in retention times may be overcome by operator manipulation of x and y coordinates of the chromatogram (Konstantinides et al, 1987), but the specific responses of basic and acidic amino acid derivatives to variations in solvent pH or ionic strength (Chan, 1984) severely complicate clear interpretation.…”

Section: Discussionmentioning

confidence: 99%

Analysis of major tomato xylem organic acids and PITC-derivatives of amino acids by RP-HPLC and UV detection

et al. 1992

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Major amino acids and organic acids in xylem exudates of tomato plants were separated by reversed phase high performance liquid chromatography (RP-HPLC) and quantified by UV detection. Before separation, amino acids were converted into their phenylisothiocyanate (PITC) derivatives. In a single run, Asp, Glu, Ser, Gin, His, Thr, Ala, Tyr, Val, Met, Cys, lie, Leu, Phe, and Lys could be separated and detected down to the pmol level. Unresolved peaks were obtained for Asn and Gly and for Arg and Pro. For organic acid analysis, exudates were pre-treated by perfusion over a prepacked Adsorbex SCX cation exchange column, to eliminate exudate amino acids. Elution recoveries for organic acids were close to 100%. The exudate organic acids were separated by ion suppression RP-HPLC chromatography, and peaks could be resolved for L-malic acid, malonic acid, maleic acid, citric acid and fumaric acid, down to the pmol level. UV signals for exudate ascorbic acid, and succinic acid were below the limits of detection. Determination of oxalic acid and tartaric acid was impossible, due to the presence of the exudate salt peak in the chromatogram. The results indicate the potential of the methods applied, and show the applicability of RP-HPLC analysis for the determination of both amino acids and organic acids in xylem exudates.

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Section: Discussionmentioning

confidence: 99%

Analysis of major tomato xylem organic acids and PITC-derivatives of amino acids by RP-HPLC and UV detection

et al. 1992

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“…Urea levels were determined by high performance liquid chromatography (Konstantinides, 1987) from culture medium sampled on day 1 and day 2. Appropriate dilutions were performed for insulin level determination on a standardized curve.…”

Section: Insulin Concentrations and Ureagenesismentioning

confidence: 99%

Primary culture of rat hepatocytes entrapped in cylindrical collagen gels: An in vitro system with application to the bioartificial liver

et al. 1992

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A static culture model employing cylindrical collagen-hepatocyte gels is reported for large scale testing of conditions relevant to the three compartment hollow fiber bioartificial liver. High density hepatocyte cultivation was achieved by cell entrapment within the collagen-hepatocyte gel. Hepatocyte viability was assessed by vital staining, gel contraction, and insulin utilization. Measures of hepatocyte-specific function included albumin synthesis, ureagenesis, lidocaine biotransformation, and cholate conjugation. Although hepatocyte viability remained stable through the seven day incubation period, hepatocyte functions were not uniformly preserved. Albumin synthesis remained stable, while representative P-450 and conjugation activities decreased with time. This static culture system will facilitate the development of a hollow fiber bioartificial liver which utilizes cylindrical collagen-hepatocyte gels.

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“…With this method we quantitated 22 individual amino acids. ammonia, and urea (7). A double peak representing cystine and cysteine was integrated as one peak for the plasma samples.…”

Section: Amino Acid Analysismentioning

confidence: 99%

Plasma Amino Acids in Long‐Term Models for Obstructive Versus Toxic Liver Injury in Developing Rats

Weisdorf,

Freese,

Radmer

et al. 1990

J. pediatr. gastroenterol. nutr.

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SummaryWe evaluated plasma amino acid (AA) concentrations associated with a histologically defined lesion caused by bile duct ligation (BDL) in developing rats. Nineteen rats that underwent BDL at 14 days of age had marked bile duct proliferation with bridging fibrosis, multifocal lobular necrosis, and minimal polymorphonuclear periportal infiltrate in their livers at sacrifice (11–31 days after ligation). These were compared to two age‐matched control groups: 21 nonoperated rats and 22 shamoperated rats; and eight rats with cirrhosis caused by carbon tetrachloride. Signs of liver damage including jaundice, growth failure, bleeding, and ascites were accompanied by elevated bilirubin, ammonia, aspartate aminotransferase (AST), and alkaline phosphatase levels in BDL rats compared to controls. They had higher concentrations of total AAs, phenylalanine, tyrosine, and cyst(e)ine when compared to controls and to CCl4‐treated rats. Micronodular cirrhosis was present in CCl4‐treated rats with elevated AST and alkaline phosphatase levels. Glutamine and glutamate levels were higher in them than in BDL rats or controls, and branched chain AA levels were lower. These two chronic lesions, one obstructive and one hepatotoxic, both result in fibrotic change, but their metabolic abnormalities as reflected in plasma AA levels are distinct. We found that BDL is an appropriate model with which to study metabolic changes and growth failure due to chronic biliary stasis during its progression to frank cirrhosis.

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Overcoming Retention Time Shifts as a Source of Error in HPLC Analysis

Cited by 11 publications

References 0 publications

Analysis of major tomato xylem organic acids and PITC-derivatives of amino acids by RP-HPLC and UV detection

Analysis of major tomato xylem organic acids and PITC-derivatives of amino acids by RP-HPLC and UV detection

Primary culture of rat hepatocytes entrapped in cylindrical collagen gels: An in vitro system with application to the bioartificial liver

Plasma Amino Acids in Long‐Term Models for Obstructive Versus Toxic Liver Injury in Developing Rats

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