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PubMed1994

Determination of adenine nucleotides by fluorescence detection using high-performance liquid chromatography and post-column derivatisation with chloroacetaldehyde.

A novel rapid method for the analysis of adenine nucleotides in cells and tissues using post-column derivatisation with chloroacetaldehyde (CAA) followed by fluorescence detection is described. The CAA is incorporated in the eluent, but only reacts post-column when the temperature is elevated to 100 degrees C. Samples are chromatographed following neutralisation of acid extracts. Examples are given using both trichloroacetic acid extraction for cells in culture, and perchloric acid for murine liver.

Acetaldehyde↗

PubMed1999

Simultaneous determination of oxalic, fumaric, maleic and succinic acids in tartaric and malic acids for pharmaceutical use by ion-suppression reversed-phase high performance liquid chromatography.

A reliable method for the simultaneous determination of oxalic, fumaric, maleic, and succinic acids in tartaric and malic acids for pharmaceutical use by reversed-phase ion-suppression high performance liquid chromatography is presented. HPLC was achieved on a Nova-Pak C18 column by isocratic elution using water adjusted to pH 2.10-2.15 with perchloric acid, and detection was by UV adsorption at a wavelength of 210 nm. This method was found to be superior to previous liquid chromatography as well as other classical assay, and to be an attractive choice for the analysis of these compounds.

Chromatography, High Pressure Liquid↗

PubMed2005

Investigation of solvent effects in capillary electrophoresis for the separation of biological porphyrin methyl esters.

The effects of organic solvents on the capillary electrophoresis (CE) separation of a number of important biological porphyrin methyl esters - six weakly basic, hydrophobic cyclic tetrapyrroles possessing two and four to eight methyl ester groups around the periphery of the porphyrin ring - were investigated in the mode of micellar electrokinetic chromatography (MEKC), microemulsion electrokinetic chromatography (MEEKC), and nonaqueous CE. In aqueous MEKC, partial separation of the six neutral porphyrin methyl esters was obtained with an organic modifier (acetonitrile) in the concentration range between 20 and 40%, in which sodium dodecyl sulfate (SDS) molecules might be present in the form of SDS micelles and/or SDS micelle-like aggregates. Relatively stable SDS micelles can be formed in nonaqueous MEKC using formamide as the separation medium, but the separation of the target analytes remained unsatisfactory. Improved resolution of all six porphyrin methyl esters was obtained using MEEKC with the running buffer consisting of 0.8% w/w n-heptane (oil phase), 2.25% w/w SDS and 1.0% w/w Brij 35 (mixed surfactant), 6.6% w/w 1-butanol (cosurfactant), and 30% v/v 2-propanol (second cosurfactant), but reproducibility in terms of peak areas for certain porphyrins (especially uroporphyrin I octamethyl ester) was found to be very poor. Best separation performances were achieved with nonaqueous CE separations in which the weakly basic porphyrin methyl esters were protonated under strongly acidic conditions (e.g., using 10 mM perchloric acid) in mixed organic solvents. For example, using a 50:50 mixture of methanol and acetonitrile as the separation medium, baseline separation of all six (positively charged) porphyrin methyl esters can be obtained within 3 min and the average precision (RSD, N = 13) in terms of migration time and peak area were 0.55 and 2.16%, respectively.

Chromatography, Micellar Electrokinetic Capillary↗

PubMed1983

Simultaneous quantitation of Krebs cycle and related acids by mass fragmentography.

Methods are described for simultaneous quantitation of Krebs cycle and related acids by gas chromatography--mass spectrometry using deuterium-labelled acids and n-butyl-d9-esters of the organic acids as internal standards. Using sulphuric acid as esterification catalyst, only lactic, succinic, fumaric, malic, maleic and citric acids were found to be stable to hydrogen exchange and could be used as reference standards in the deuterated form. In contrast, pyruvic, oxalacetic, alpha-ketoglutaric and malonic acids were found to exchange their deuterium readily and could not be employed for this purpose. All the acids could be quantitated using n-butyl-d9-esters of reference organic acids as internal standards, following a separate preparation of the n-butyl derivatives of the unknown acids. The method is suitable for routine analysis of organic acids at the picogram level in perchloric acid extracts of tissues.

Adipates↗

PubMed1989

Measurement of catecholamines, their precursor and metabolites in human urine and plasma by solid-phase extraction followed by high-performance liquid chromatography with fluorescence derivatization.

A high-performance liquid chromatographic method is described for the determination in human urine and plasma of catecholamines, their precursor and metabolites [amino compounds (norepinephrine, epinephrine, dopamine, normetanephrine, metanephrine, 3-methoxytyramine and L-DOPA), acidic compounds (3,4-dihydroxymandelic acid, 3,4-dihydroxyphenylacetic acid, vanillylmandelic acid and homovanillic acid) and alcoholic compounds (3,4-dihydroxyphenylethyleneglycol and 4-hydroxy-3-methoxyphenylethyleneglycol)]. Urine (0.5 ml) containing 3,4-dihydroxybenzylamine and 4-hydroxy-3-methoxycinnamic acid (internal standards) is deproteinized with perchloric acid, and the resulting solution is fractionated by solid-phase extraction on a strong cation-exchange resin cartridge (Toyopak IC-SP S) into two fractions (amine fraction and acid-alcohol fraction), which include 3,4-dihydroxybenzylamine and 4-hydroxy-3-methoxycinnamic acid, respectively. Plasma (0.7 ml) is deproteinized in the presence of 3,4-dihydroxybenzylamine (internal standard) in the same manner, and the resulting solution is directly used as an acid-alcohol fraction, while an amine fraction is obtained as for urine. Each fraction is subjected to the previously established ion-pair reversed-phase chromatography with post-column derivatization involving coulometric oxidation followed by fluorescence reaction with 1,2-diphenylethylenediamine. The detection limits, at a signal-to-noise ratio of 5, of the compounds measured in urine are 300 pmol/ml for the two mandelic acids, 2-7 pmol/ml for the other acidic and alcoholic compounds, 12 pmol/ml for L-DOPA and 0.6-2 pmol/ml for the other amino compounds; the corresponding values for plasma samples are 80, 0.5-3, 10 and 0.6-3 pmol/ml, respectively.

Catecholamines↗

PubMed1991

Receptor for mouse hepatitis virus is a member of the carcinoembryonic antigen family of glycoproteins.

The receptor for mouse hepatitis virus (MHV), a murine coronavirus, is a 110- to 120-kDa glycoprotein on intestinal brush border membranes and hepatocyte membranes. The N-terminal 25-amino acid sequence of immunoaffinity-purified MHV receptor was identical to the predicted mature N termini of two mouse genes related to human carcinoembryonic antigen (CEA) and was strongly homologous to the N termini of members of the CEA family in humans and rats. Polyclonal antibodies to human CEA recognized the immunoaffinity-purified MHV receptor and the MHV receptor in liver membranes and intestinal brush border membranes from MHV-susceptible mouse strains. In membranes from MHV-resistant SJL/J mice, the anti-CEA antibodies recognized a homologous glycoprotein that failed to bind MHV. The MHV receptor glycoprotein was detected in membranes of BALB/c colon, small intestine, and liver, which are the principal targets for MHV replication in vivo. The MHV receptor glycoprotein resembled members of the human CEA family in molecular weight, acidic pI, extensive glycosylation, solubility in perchloric acid, and tissue distribution. Thus, the MHV receptor is, to our knowledge, the first member of the CEA family of glycoproteins to be identified as a virus receptor.

Amino Acid Sequence↗

PubMed1986

Multielemental characterization of human lung tissues by ICP-AES.

Preliminary results on multielement analysis of human lung tissues with inductively coupled plasma atomic emission spectrometry (ICP-AES) are reported. Three different sample preparation procedures have been studied; dry ashing at 450 degrees C or low temperature ashing followed by pressure digestion with aqua regia and hydrofluoric acid or direct acid digestion with nitric-, sulfuric- and perchloric acid.

Elements↗

PubMed1980

Effect of glucagon on digestive enzyme synthesis, transport and secretion in mouse pancreatic acinar cells.

1. Effect of glucagon on amylase secretion and lactic dehydrogenase (LDH) release from functionally intact dissociated pancreatic acinar cells and acini was studied. 2. In dissociated rat pancreatic acinar cells, the rate of amylase secretion was increased by 70% with bethanechol (maximally effective concentration, 10(-4) M) and 125% with A23187 (10(-5) M), but the response to cholecystokinin-pancreozymin (CCK-PZ) was inconsistent. In dissociated cells from mouse pancreas, the increases amounted to 78% with bethanechol (10(-4) M), 134% with A23187 (10(-5) M) and 82% with CCK-PZ (maximally effective concentration, 0 . 01 u. ml.-1). Glucagon in concentrations ranging from 10(-7) to 10(-4) M increased amylase secretion by 3, 26, 67 and 80%, whereas secretin (10(-8)--10(-5) M) increased amylase secretion by 8, 39, 88 and 138%. LDH release was increased with A23187 in concentrations greater than 10(-6) M. 3. CCK-PZ, bethanechol and A23187 used in maximal concentrations potentiated the effect of a submaximal dose of glucagon whereas secretin did not have an additive or a potentiating effect. 4. Pancreatic acini were approximately 3 times more responsive to secretagogues than cells. The dose--response curves to bethanechol, glucagon and CCK-PZ for increase in amylase secretion were similar. LDH release was not increased by these agents. Cytochalasin B (5 microgram ml.-1) which is known to disrupt the integrity of luminal membrane inhibited the amylase secretion stimulated by glucagon, bethanechol and CCK-PZ. 5. Glucagon inhibited incorporation of a mixture of fifteen 14C-labelled amino acids (algal profile, Schwarz Mann) into perchloric acid precipitable proteins in dissociated mouse pancreatic acini within 30 min. 6. In 'pulse-chase' experiments, glucagon decreased the specific activity of zymogen granules isolated by differential centrifugation, from pancreatic lobules (120 min) and increased the specific activity of radiolabelled proteins in the medium (60 and 120 min). 7. It is concluded that glucagon increased digestive enzyme secretion from pancreatic acinar cells by a direct action (in contrast to its reported indirect effect in vivo) and decreased digestive enzyme synthesis. The data on transport and secretion do not support the suggested role of glucagon as an inhibitor in the intact animal.

Amino Acids↗

PubMed2005

Interference and blood sample preparation for a pyruvate enzymatic assay.

BACKGROUND: To assess the severity of circulatory failure, a pyruvate enzymatic assay was performed on whole blood using lactate dehydrogenase to catalyze the conversion of pyruvate to lactate. We investigated factors related to blood sample collection and preparation that might influence the results, including the timing of blood deproteinization, temperature of sample storage, and hemolysis. METHOD: A total of 25 whole blood specimens were collected for this study. Each sample was divided into 2 parts: one stored at room temperature (RT) and another kept on ice. The samples were deproteinizied by using 8% perchloric acid (PCA) at varying times after collection; the first deproteinization was immediately after the blood was drawn (0 h), then at 1 h intervals for 6 h and also in samples kept overnight. The supernatant samples were analyzed soon after deproteinization using a COBAS Centrifugal Analyzer. In another set of samples, the blood was immediately deproteinized, and the supernatants were stored at RT and 4 degrees C and assayed for pyruvate at varying times, as above. Finally, the effect of hemolysis on the blood pyruvate enzymatic assay was also evaluated. RESULTS: When samples were stored at RT, pyruvate levels remained constant until the third h after deproteinization, when there was an approximately 13.3% increase in pyruvate concentration. When whole blood samples were kept at 4 degrees C before deproteinization, pyruvate levels were significantly reduced over time, ranging from 37.8% to 62.2% (paired t test showed a significant mean difference, P < 0.001). No significant differences in pyruvate concentration were observed in supernatant stored at either RT or 4 degrees C. Hemolysis caused a 33.7% increase in the pyruvate concentration, equivalent to 0.18 mg pyruvate per gram per deciliter of hemoglobin. CONCLUSIONS: For a pyruvate enzymatic assay, keeping a whole blood sample at RT will not cause a significant difference in the pyruvate level as long as the sample is immediately deproteinized. Whole blood samples should not be stored in an ice bath for transport, nor should hemolyzed samples be used for a blood pyruvate enzymatic assay.

Adult↗

PubMed2006

Analysis of amino acids and biogenic amines in biological tissues as their o-phthalaldehyde/ethanethiol/fluorenylmethyl chloroformate derivatives by high-performance liquid chromatography. A deproteinization study.

The extraction of ornithine, lysine, putrescine, cadaverine, 1,7-diaminoheptane, spermidine and spermine from biological tissues was optimized for HPLC quantitation as their o-phthalaldehyde/ethanethiol/fluorenylmethyl chloroformate (OPA/ET/FMOC) derivatives. In applying perchloric acid deproteinization two approaches have been followed: (i) deproteinization with subsequent neutralization by potassium hydroxide and lyophilization, and (ii) deproteinization without neutralization and lyophilization. Neutralization and lyophilization resulted in the loss of free biogenic amines. HPLC analysis of ornithine (Orn), lysine (Lys), putrescine (Put), cadaverine (Cad), 1,7-diaminoheptane (Dah), spermidine (Spd) and spermine (Spm) content of biological tissues as their OPA/ET/FMOC derivatives was performed in the supernatant of perchloric acid-deproteinized samples (model solutions and tissues) with an average reproducibility of < or =2.6% relative standard deviation (RSD), including recovery of sample treatment and chromatography.

Amino Acids↗

PubMed1994

Interrelationship between thyroxine and estradiol on the secretion of thyrotropin-releasing hormone and dopamine into hypophysial portal blood in ovariectomized-thyroidectomized rats.

Effects of thyroxine (T4) on the secretion of thyrotropin-releasing hormone (TRH) and catecholamines into hypophysial portal blood and on the concentrations of arterial plasma thyroid-stimulating hormone (TSH) and prolactin (PRL) in ovariectomized and thyroidectomized (Ovx-Tx) rats were studied. Immediately after ovariectomy, rats were Tx or sham Tx. The Ovx-Tx rats were injected subcutaneously with estradiol benzoate (EB, 0.5 microgram/kg b.w.) or sesame oil, and T4 (20 micrograms/kg b.w.) or saline once daily for 2 weeks. The Ovx rats with intact thyroid gland were injected with saline and oil only. The hypophysial portal blood samples were collected and mixed with or without 2,3-dimercaptopropanol before extraction by methanol or perchloric acid, respectively. The femoral arterial blood was also collected. The concentrations of TRH in methanol-extracted portal plasma and that of TSH and PRL in arterial plasma were measured by radioimmunoassay. The concentrations of catecholamines in perchloric acid-extracted portal plasma samples were measured by radioenzymatic assay. Thyroidectomy in Ovx rats resulted in an increase in portal plasma TRH and arterial plasma TSH. Despite the presence or absence of estradiol, T4 replacement in Ovx-Tx rats decreased portal plasma TRH and arterial plasma TSH to euthyroid levels. Combination of the injection of T4 and EB in vivo caused significantly decreased levels of portal plasma dopamine and increased arterial plasma PRL compared with those in vehicle-injected Ovx-Tx animals. Concentrations of neither norepinephrine nor epinephrine in hypophysial portal plasma paralleled the altered concentrations of PRL or TSH in arterial plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1984

Determination of creatine phosphate levels in brain tissue by isocratic reverse-phase, ion-paired high-performance liquid chromatography.

The utilization of isocratic, reverse-phase, ion-paired high-performance liquid chromatography for analysis of creatine phosphate allows for rapid quantification of multiple samples. Cryogenic sample handling and the addition of ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid as a Ca2+ sequestering agent during perchloric acid extraction enhance maximal recovery of creatine phosphate from brain samples. Peak identification is supported by a complete enzymatic shift with a phosphocreatine kinase, hexokinase, and glucose-6-phosphate dehydrogenase system.

Animals↗

PubMed1992

Determination of platelet monoamine oxidase activity by high-performance liquid chromatography with electrochemical detection.

A procedure for determining human platelet monoamine oxidase (MAO) with dopamine (DA) as substrate is described. High-performance liquid chromatography (HPLC) with electrochemical detection (ED) was used to separate and detect components of the reaction mixture. The method for platelet preparation was also improved and only 2 ml of blood were required. Following a 10-min incubation of the platelet preparation with DA in 0.1 M Tris buffer (pH 9.0), excess DA substrate was removed by adsorption on a cation-exchange resin. The reaction product, 3,4-dihydroxyphenylacetaldehyde, was adsorbed on acid-washed alumina, eluted with 0.1 M perchloric acid and analyzed by HPLC. Simple, clean chromatograms were obtained with good reproducibility using 3,4-dihydroxybenzylamine as an internal standard. The within-sample, between-samples and between-day relative standard deviations were 0.9, 3.7 and 6.1%, respectively. The apparent Michaelis constant and maximum velocity were 0.10 mM and 0.37 nmol/min.mg protein, respectively. This HPLC-ED method offers a good alternative to methods using radioactivity.

Blood Platelets↗

PubMed1988

High-performance liquid chromatography of biogenic amines, derivatized with 9-fluorenylmethyl chloroformate.

A procedure was elaborated for the analysis of three biogenic amines posing a considerable health hazard. The method takes advantage of the characteristics of the 9-fluorenylmethyl chloroformate (FMOC) derivative, namely specificity, stability and compatibility for either fluorescence or UV-absorbance detection. The FMOC-tyramine derivative was probably adsorbed to labware when acetone served as the solvent for FMOC. Methanol, substituted for acetone, removed this problem. Excellent linearity was obtained with standard solutions of tyramine, tryptamine and phenylethylamine. Meat samples, spiked with the mentioned amines, also showed good linearity. Perchloric acid was chosen for deproteinization, as potassium perchlorate may be eliminated on neutralization. Histamine failed to react with FMOC or was not detected under the test conditions.

Animals↗

PubMed2003

Trace perchlorates in a radiological liquid-waste treatment facility.

Waste management programs at the Radioactive Liquid Waste Treatment Facility (RLWTF) at the Los Alamos National Laboratory (LANL) are concerned with the levels of perchlorates due to the effects it can have on the environment and resultant regulations. The RLWTF treats industrial and radioactive wastes generated at multiple research and production facilities across the LANL. Perchloric acid is the major source of the perchlorate ion in the RLWTF used in the analytical chemistry laboratories and for metal dissolution. Perchlorate is present in the influent to the RLWTF at concentrations up to several thousands microg/l level. Ion chromatography is the method of choice to analyze the concentrations of perchlorate in the wastewater generated at the RLWTF. Perchlorate was separated by elution through a CS16/CG16 with an EG40 eluent generator. To minimize background conductivity and enhance analyte conductance, an anion self-regenerating suppressor was used. The method achieved a perchlorate method detection limit of 1 microg/l. The method is successfully being used to monitor the perchlorate levels at the RLWTF and provide data for the pilot tests to remove perchlorate from the RLWTF effluent.

Chromatography, Ion Exchange↗

PubMed2003

The 2-oxocyclohexanecarboxylic acid keto-enol system in aqueous solution.

Flash photolysis of 2-diazocycloheptane-1,3-dione or 2,2-dimethyl-5,6,7,8-tetrahydrobenzo-4H-1,3-dioxin-4-one in aqueous solution produced 2-oxocyclohexylideneketene, which underwent hydration to the enol of 2-oxocyclohexanecarboxylic acid, and the enol then isomerized to the keto form of the acid. Isomerization of the enol to keto forms was also observed using solid enol, a substance heretofore commonly believed to be the keto acid. Rates of ketonization were measured in perchloric acid, sodium hydroxide, and buffer solutions, and a ketonization rate profile was constructed. Rates of enolization of the keto acid were also measured using bromine to scavenge the enol as it formed. Rates of enolization and ketonization were then combined to provide the keto-enol equilibrium constant pK(E) = 1.27. This and some of the other results obtained are different from the corresponding quantities for the 2-oxocyclopentanecarboxylic acid keto-enol system. These differences are discussed.

Journal Article↗

PubMed1969

Fractionation of phytohemagglutinin. I. Purification of the RNA and DNA synthesis-stimulating substances and evidence that they are not proteins.

We have separated the RNA synthesis-stimulating activity and the DNA synthesis-stimulating activity of extracts of Phaseolus vulgaris (phytohemagglutinin) from the erythroagglutinins, leukoagglutinins, and cytotoxic factors. We have shown that the substances stimulating the synthesis of nucleic acids are probably not proteins, since they are not significantly affected by rigorous deproteinization or treatment by trypsin and pronase. Likewise, they do not appear to be nucleic acids, since they are not precipitated by perchloric acid and resist RNase, DNase, and phosphodiesterases. They are probably not carbohydrates, since 98 per cent of the carbohydrate can be removed from a preparation with only a moderate loss in activity. The RNA and DNA synthesis-stimulating activities are probably associated with separate molecules, since they are destroyed by periodate at different rates.

Animals↗

PubMed1998

[Separation and determination of naproxen by reversed-phase high performance liquid chromatography].

A reversed-phase HPLC method has been developed for the separation and determination of naproxen and its bromo-substituted compound. These compounds were separated on a Shim-pack CLC ODS column (5 microns, 250 mm x 4.6 mm i.d.) by using a methanol-water (80/20, V/V) solution containing 50 mmol/L lactic acid and adjusted to pH 2.5 with perchloric acid as mobile phase, with flow rate of 0.8 mL/min and UV detection at 271 nm. Benzoic acid was selected as an internal standard. At the concentration range of 5-100 mg/L, the linear internal standard working curves with r > 0.9995 were obtained. The accuracy of this method for naproxen and its bromo-substituted compound were 99.83%-102.07% and 99.00%-100.83%, and RSD were < 2.58% and < 3.64% respectively.

Anti-Inflammatory Agents, Non-Steroidal↗