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PubMed1983

Interference with carcinoembryonic antigen radioimmunoassays by glycosaminoglycans, and their removal.

Using the reagents from the CEA-Roche kit, we found that solutions containing only glycosaminoglycans (GAG) yielded false concentrations of carcinoembryonic antigen (CEA), and mixtures of CEA and GAG produced falsely high values. On the other hand, solutions of GAG yielded no additional CEA concentration when reagents from the Abbott CEA kit were used; rather, the CEA result was decreased with the Abbott kit for a CEA solution also containing GAG. These effects of GAG were not ascribable to contamination, because neither gel filtration nor ion-exchange column chromatography separated the false Roche CEA content related to GAG from their peaks of uronic acid or from their anticoagulant activity. In addition, an enzyme specific for GAG eliminated these GAG-derived false concentrations. Both the positive and negative effects are correlated with concentrations of GAG. We found that the concentration of GAG could be decreased in a solution containing plasma proteins by either heating (70 degrees C, 15 min) or treating with perchloric acid (0.6 mol/L). The former is superior because essentially all GAG added to a solution containing plasma proteins were removed by heat, whereas as much as 25% to 80% of the GAG still remained after acid treatment. The effect of GAG was also completely eliminated by treating the specimens with chondroitinase ABC lyase (EC 4.2.2.4).

Carcinoembryonic Antigen↗

PubMed1982

Immunological similarity of CEA with alpha 1-acid glycoprotein (orosomucoid).

We have demonstrated that 125 I-CEA (carcinoembryonic antigen) from two commercial sources (Roche and CIS RIA kit) can be precipitated by antibody to alpha 1-acid glycoprotein (AG) dose-dependently. The binding of 125 I-CEA to anti-AG can be displaced by unlabelled AG, though, there was no cross-reaction between AG and anti-CEA. The data strongly suggest that CEA has an immunological similarity to AG. The perchloric acid extract from cancerous tissue was fractionated on a Sephadex G-200 column, and the first eluted fraction (containing large amounts of CEA) was subjected to affinity chromatography using anti-AG bound to Sepharose. The bound fraction was eluted, labelled with 125 I, and then applied to a Sephadex G-200 column with carrier protein. The radioactivity was found mainly in the large molecular size eluted fraction (Fr 1). Almost all radioactivity of Fr 1 was precipitated by anti-AG and anti-CEA. This experiment also demonstrated that a large molecular weight component (Mr: 180 000) obtained from tumor was immunologically related to both CEA and AG. Based on differences in binding affinities between CEA with anti-CEA and with anti-AG we postulate that CEA may be a large molecular precursor of AG (big form of AG).

Carcinoembryonic Antigen↗

PubMed2004

Transition-state effects in acid-catalyzed aryl epoxide hydrolyses.

The hydronium ion-catalyzed hydrolyses of 5-methoxyindene 1,2-oxide and of 6-methoxy-1,2,3,4-tetrohydronaphthalene-1,2-epoxide were each found to yield 75-80% of cis diol and only 20-25% of trans diol as hydrolysis products. The relative stabilities of the cis and trans diols in each system were determined by treating either cis or trans diols with perchloric acid in water solutions and following the approach to an equilibrium cis/trans mixture as a function of time. These studies establish that the trans diol in each system is more stable than the corresponding cis diol. Thus, acid-catalyzed hydrolysis of each epoxide, which proceeds via a carbocation intermediate, yields the less stable cis diol as the major product. Transition-state effects, presumably of a hydrogen-bonding nature, selectively stabilize the transition state for attack of water on the intermediate 2-hydroxy-1-indanyl carbocation leading to the less stable cis diol in this system. Transition-state effects must also be responsible for formation of the less stable cis diol as the major product in the acid-catalyzed hydrolysis of 5-methoxy-1,2,3,4-tetrahydronaphthalene 1,2-epoxide. However, in this system steric effects at the transition state may be more important than hydrogen bonding in determining the cis/trans diol product ratio. The synthesis of 5-methoxyindene 1,2-oxide and a study of its rate of reaction as a function of pH in water and dioxane-water solutions are reported. Both an acid-catalyzed reaction leading to only diol products and a pH-independent reaction yielding 71% of 5-methoxy-2-indanone and 29% of diols are observed; the half-life of its pH-independent reaction in water is only 2.4 s.

Acids↗

PubMed2000

New technique for increasing retention of arginine on an anion-exchange column.

A method is described for enhancing retention of arginine on a pellicular anion-exchange column. Arginine exhibits adjustable increases of retention time that are dependent on the acidity of standard or sample matrix. This effect is based on interactions of the protonated form of arginine with the residual cation-exchange groups on the core beads of pellicular particles. The relative magnitude of retention time shift of arginine is evaluated for identical concentrations of hydrochloric, sulfuric, and perchloric acids. Although the direct addition of acid is very effective in influencing the retention of arginine, it affects peak shapes and retention of other peaks in the chromatographic separation. The new technique-acid coinjection-achieves a similar retention enhancement for arginine with only a minimal effect on the rest of the separation. Detection limits, reproducibility results, and calibration data are presented for the chromatography of amino acids with acid coinjection. Improved resolution of arginine is demonstrated with chromatograms of soybean hydrolysate and cell culture samples.

Arginine↗

PubMed1985

Studies on 18F-labeled pyrimidines III. Biochemical investigation of 18F-labeled pyrimidines and comparison with 3H-deoxythymidine in tumor-bearing rats and mice.

Metabolic studies of 18F-labeled 5-fluoro-2'-deoxyuridine(FdUrd), 5-fluorouridine(FUrd) and 5-fluorouracil (FUra) were performed in tumor-bearing rats and mice. Also, the usefulness of 18F-FdUrd and 3H-deoxythymidine (dThd) for tumor detection was compared. In the tumor, 2 h after the injection of the 18F-pyrimidines, 3%-11% and 6%-14% of the 18F was present in the nuclear and microsomal fractions, respectively, and 17%-34% and 19%-24% of the 18F was incorporated into the acid-insoluble and nucleotide fractions, respectively. Of the three 18F-pyrimidines, 18F-FUrd demonstrated the highest incorporation rate, while 18F-FUra showed the lowest incorporation rate. The incorporation in the spleen, small intestine, and liver was less than that in the tumor. 3H-dThd and 18F-FdUrd were injected into the same mice. The 3H-dThd was accumulated in the spleen, small intestine, and tumor, and in these three tissues significant amounts of the 3H were incorporated into acid-insoluble materials. However, the clearance of 18F-FdUrd was slow in the tumor but rapid in the spleen and small intestine. In the autoradiograms of the tumor, 18F and 3H showed a slightly different distribution. Both distribution patterns were unchanged when the soluble materials were rinsed out with perchloric acid. For tumor detection, 18F-FdUrd gives the same information as radio-dThd, and further information can be obtained by positron-emission tomography.

Animals↗

PubMed1977

Ultrastructural cytochemistry of the human adrenal medulla.

A cytochemical study of the human adrenal medulla showed that it is made up of two types, the adrenaline (A-) and noradrenaline (N-) storing cells. A-and N-storing granules were argentaphobic when ultra-thin sections of Araldite-embedded medulla were stained according to the periodic acid-thiocarbohydrazide silver proteinate technique of Thiery. A small amount of glycogen (which disappeared after digestion with alpha amylase) in the form of B-particles, as well as lysosomes were, however, visualized by this technique. The entire core of A granules was markedly positive after ultrathin sections of glutaraldehyde-fixed, glycol methacrylate (GMA-) embedded medullae were stained with phosphotungstic acid (PTA) at a low pH (O.3). The N granules, in contrast, were mostly unreactive. PTA stained a large part of the Golgi complex of A cells, whereas it generally had no such effect on that of the N cells. In both cell types, the cell coat, lysosomes and multivesicular bodies reacted to PTA. The periodic acid schiff (PAS) technique showed A but not N granules in semithin sections of GMA-or Araldite-embedded medullae. The PTA and PAS stains were abolished by acetylation, restored by saponification, unchanged by methylation and greatly diminished by sulfation or by digestion with beta glucuronidase after oxidation by perchloric acid. These results indicate that in man the A granules and the Golgi complex of A cells, unlike the same structures in N cells, are rich in glycoproteins.

Adrenal Medulla↗

PubMed1981

Analysis of some tryptophan and phenylalanine metabolites in urine by a straight-phase high-performance liquid chromatographic technique.

A high-performance liquid column chromatographic technique is reported for the analysis of some tryptophan and phenylalanine acid metabolites in the urine. An acidified and NaCl-saturated urine sample is loaded on to a C18-bonded silica microcolumn. After washing the microcolumn with clean and deionized water, the metabolites of interest are selectively extracted by successive elutions with organic solvents of variable polarity. Acids are eluted first and the neutral compounds with the next fraction. Basic compounds and other neutral substances of higher polarities were eliminated during the washing procedure. The chromatography was performed in the straight-phase isocratic elution mode utilizing 5-micrometers silica-gel columns loaded with a triethanolammonium perchlorate--perchloric acid aqueous solution. The separation achieved have permitted the application of the chromatographic technique to the analysis of urinary metabolites with acceptable accuracy.

Chromatography, High Pressure Liquid↗

PubMed2005

Determination of biogenic amines in chocolate by ion chromatographic separation and pulsed integrated amperometric detection with implemented wave-form at Au disposable electrode.

A rapid and selective cation exchange chromatographic method coupled to integrated pulsed amperometric detection (PAD) has been developed to quantify biogenic amines in chocolate. The method is based on gradient elution of aqueous methanesulfonic acid with post column addition of strong base to obtain suitable conditions for amperometric detection. A potential waveform able to keep long time performance of the Au disposable electrode was set up. Total analysis time is less than 20min. Concentration levels of dopamine, serotonin, tyramine, histamine and 2-phenylethylamine were measured, after extraction with perchloric acid from 2g samples previously defatted twice with petroleum ether. The method was used to determine the analytes in chocolate real matrices and their quantification was made with standard addition method. Only dopamine, histamine and serotonin were found in the analysed real samples. Repeatabilities of their signals, computed on their amounts in the real samples, were 5% for all of them. Repeatabilities of tyramine and phenethylamine were relative to standard additions to real samples (close to 1mg/l in the extract) and were 7 and 3%, respectively. Detection limits were computed with the 3s of the baseline noise combined with the calibration plot regression parameters. They were satisfactorily low for all amines: 3mg/kg for dopamine, 2mg/kg for tyramine, 1mg/kg for histamine, 2mg/kg for serotonin, 3mg/kg for 2-phenylethylamine.

Biogenic Amines↗

PubMed1990

Effects of amino acids on acute alcohol intoxication in mice--concentrations of ethanol, acetaldehyde, acetate and acetone in blood and tissues.

Condensation reactions between some SH-amino acids (L-and D-cysteine 1%) and acetaldehyde (50 microM) were studied in vitro experiment. In the aqueous solution, free acetaldehyde was reduced to 41.3% by L-cysteine and to 36.4% by D-cysteine. In the reaction with human blood medium, after the medium was deproteinized with perchloric acid reagent, acetaldehyde was reduced to 47.0% by L-cysteine and to 43.8% by D-cysteine. D-Cysteine appears to have great stability of reacting acetaldehyde. In vitro experiment reactability for D-cysteine exhibited 3-8% higher than that for L-cysteine. Next, effects of some amino acids on alcohol metabolism were studied in male ICR mice. The animals were given ethanol through a gastric catheter at a dose of 2 g/kg and they were intraperitoneally injected L-cysteine (300 mg/kg), D-cysteine (300 mg/kg), L-alanine (300 mg/kg) and control (saline), respectively in the period of one hour before the injection of ethanol. Blood and tissues samples were analyzed for ethanol, acetaldehyde, acetate and acetone during alcohol intoxication in mice by head space gas chromatography. In the groups administered D-cysteine and L-cysteine, the mice showed a definitely faster oxidation and disappearance of ethanol. Especially in the D-cysteine group, ethanol levels in blood, liver and brain remained lower than that in the other groups (p less than 0.01). Acetaldehyde levels in blood, liver and brain remained low by L-cysteine. Ethanol metabolites during alcohol oxidation by chemical reactabilities of L- and D-cysteine showed different distribution in the mice, respectively. In the mice received L-alanine, acetate and acetone levels in blood, liver and brain were distinctly reduced (p less than 0.01). L-Alanine is reported to supply an abundance of pyruvic acid that performs the NAD-generating system. NAD produced is introduced to alcohol metabolism and the TCA cycle. It was thus presumed that the L- or/and D-cysteine, and L-alanine was effective in acute alcohol intoxication by heavy drinking.

Acetaldehyde↗

PubMed1988

Purification and composition of the human tumor-associated glycoprotein (TAG-72) defined by monoclonal antibodies CC49 and B72.3.

Human mammary and other carcinoma cells secrete and express on their cell surfaces complex, mucin-like glycoproteins (Mr greater than 10(6] that are recognized as tumor-associated antigens by a variety of monoclonal antibodies (MAbs). One such MAb, B72.3, has been extensively studied as to range of reactivity for a variety of carcinomas versus normal tissues. The B72.3-reactive antigen, designated tumor-associated glycoprotein (TAG)-72, which is a high-molecular-weight mucin, was partially purified and used as immunogen to produce second generation anti-TAG-72 MAbs. One of these second generation MAbs, CC49, was chosen to be used to develop a procedure to yield preparative amounts of purified antigen suitable for analyzing amino acid sequence. One of the reasons for the selection of CC49 for these studies is that it demonstrated a higher Ka for TAG-72 compared with B72.3. Xenografts of LS174T cells (a human colon carcinoma cell line) grown in nude mice were solubilized, extracted with several chaotropic agents and treated with perchloric acid. The acid soluble antigen was subjected to MAb CC49 affinity chromatography, gel filtration, and ion-exchange chromatography using fast protein liquid chromatography and high-performance liquid chromatography methodologies. A double-determinant liquid competition radioimmunoassay for TAG-72 showed greater than a 1000-fold purification. Radiolabeled protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated an apparently homogeneous high molecular weight mucin and a small amount of an additional protein with an apparent Mr of 63,000. Chemical deglycosylation using trifluoromethanesulfonic acid yielded low molecular weight proteins, which could be analyzed for amino acid sequence, and also became susceptible to tryptic digestion. The amino acid composition of the purified TAG-72 mucin was similar to that of other purified mucins.

Amino Acids↗

PubMed1986

Factors affecting determination of delta-aminolevulinate by use of Ehrlich's reagent.

We investigated the formation of delta-aminolevulinic acid (ALA)-pyrrole and subsequent color development used in determining ALA in urine. Of three condensation reagents examined--acetylacetone, ethyl acetoacetate, and methyl acetoacetate--the last was the best. When the ALA-pyrrole is reacted with Ehrlich's reagent in ethyl acetate according to one procedure, the optimum concentration of perchloric acid in the reagent is 0.5 to 1.0 mol/L. Its optimum concentration is 1.0 to 2.3 mol/L when the reaction takes place in water.

Aminolevulinic Acid↗

PubMed1983

Mathematical analysis of isotope labeling in the citric acid cycle with applications to 13C NMR studies in perfused rat hearts.

Rat hearts have been perfused in vitro with 5 mM glucose and either 5 mM acetate or 1 mM pyruvate to achieve steady state conditions, followed by replacement of the acetate with 90% enriched [2-13C]acetate or pyruvate with 90% enriched [3-13C]pyruvate. The hearts were frozen different times after addition of 13C-substrate and neutralized perchloric acid extracts from three pooled hearts per time point were used to obtain high resolution proton-decoupled 13C NMR spectra at 90.55 MHz. The 13C fractional enrichment of individual carbons of different metabolites was calculated from the area of the resolved resonances after correction for nuclear Overhauser enhancement and saturation effects. A mathematical flux model of the citric acid cycle and ancillary transamination reactions was constructed with the FACSIMILE program, and used to solve unknown flux parameters with constant pool sizes by nonlinear least squares analysis of the approximately 200 simultaneous differential equations required to describe the reactions. With [2-13C] acetate as substrate, resonances and line splittings due to 13C-13C spin coupling of the C-2, C-3, and C-4 carbons of glutamate were well resolved. The half-times to reach maximum 13C enrichment were 2.6 min for glutamate C-4 and 8 min for glutamate C-2 and C-3. From these data, a well determined citric acid cycle flux of 8.3 mumol/g dry weight X min was calculated for an observed oxygen consumption of 31 mumol/g dry weight X min. With [3-13C]pyruvate as substrate, resonances of aspartate C-2 and C-3 and of alanine C-3 were well resolved in addition to those of glutamate C-2, C-3, and C-4. Nonlinear least squares fitting of these data to the model gave nonrandomly distributed residuals for the 13C fractional enrichments of glutamate C-4, suggesting an incomplete model, but a well determined cycle flux of 11.9 mumol/g dry weight X min for an oxygen uptake of 35 mumol/g dry weight X min. Our studies demonstrate the practicality of 13C NMR, used in conjunction with mathematical modeling, for the measurement of metabolic flux parameters in living systems.

Animals↗

PubMed1993

31P NMR examination of phosphorus metabolites in the aqueous, acidic, and organic extracts of Phaseolus vulgaris seeds.

31P NMR spectroscopy was used to compare the phosphorus compound content in aqueous, acidic, and organic extracts of Phaseolus vulgaris seeds. Two chloroform-methanol and three ethanol extractions were used to isolate phospholipids from dry cotyledons and the phospholipid profiles were compared. Variations in phospholipid composition and artificially high concentrations of lysophosphatidylcholine were observed in the ethanol extracts. Other phosphorus compounds were extracted using perchloric acid, trichloroacetic acid, trichloroacetic acid in ether, hydrochloric acid, boiling water, and aqueous Hepes. The Hepes extraction was introduced in order to compare the results of a gentle procedure with those involving heat and acid treatments. Low concentrations of phospho-sugars and other phosphorus metabolites were found in all these extracts. High concentrations of phytate were found in all aqueous and acidic extractions; however, 31P NMR spectra of aqueous extractions did not show the phytate resonance. The NMR silence of the phytate resonances is attributed to complexation of phytate. The 31P NMR spectra of aqueous extracts contained a broad resonance at 0.1 ppm assigned to protein-bound RNA. Various extraction procedures on the same biological material are presented, and the comparison of these methods will facilitate future analysis and interpretation of literature reports involving these methods of tissue analysis.

Chemistry Techniques, Analytical↗

PubMed1980

Increased phosphorylation of specific nuclear proteins in superior cervical ganglia and PC12 cells in response to nerve growth factor.

Treatment of rat superior cervical ganglia in culture with nerve growth factor (NGF) increases the amount of radioactive phosphate incorporated into a nuclear protein band. This band migrates coincidentally with H1 histone on 10% sodium dodecyl sulfate/polyacrylamide gels. The increase in phosphate incorporation is at least 70% and occurs only in tissues known to be responsive to NGF. It is not produced by treatment with related peptides, but is observed after the addition of dibutyryl cyclic AMP. An increase in phosphorylation can be detected after 1 h, and can be seen with as little as 10 ng/ml of NGF in the medium. Neither actinomycin D nor cycloheximide inhibits the effect. When the nuclei are extracted with 0.2 M H2SO4 and the extract analyzed on acid-urea/polyacrylamide gels, two NGF-responsive proteins can be detected. One protein again migrates with the H1 histone marker; the other migrates more slowly than H1. These two NGF-responsive proteins have molecular weights of approximately 30,000 and are chromatin-bound. They are not soluble in 5% perchloric acid, but can be extracted from the nuclei with 0.35 M NaCl. No increase in the phosphorylation of these proteins was seen in ganglia from 6-hydroxydopamine-treated rats. The phosphorylation of the proteins in both control and NGF-treated ganglia occurs almost exclusively on serine residues. The amino acid compositions of the two nuclear proteins show that they are different from the H1 histone and different from each other. Both nerve growth factor (NGF) and epidermal growth factor (EGF) increase the incorporation of radioactive phosphate into a specific nuclear protein in cultures of PC12, a clone of rat pheochromocytoma. Purified NGF antibody blocks the effect of NGF, but not that of EGF; EGF antiserum neutralizes the effect of EGF, but not that of NGF. Insulin, glucagon, and dexamethasone are without effect. The increase in phosphorylation due to NGF can be detected within 1 h. Dibutyryl cyclic AMP increases the phosphorylation of this protein, but dibutyryl cyclic GMP does not. Neither the uptake nor the overall incorporation of [32P]orthophosphate is altered by NGF, EGF, or dibutyryl cAMP under the present experimental conditions. The nuclear protein exhibiting increased radioactivity is similar in solubility, size, and amino acid composition to one of the NGF-responsive nuclear proteins from sympathetic ganglia.

Adrenal Gland Neoplasms↗

PubMed1990

Acid lability of metabolites of 2-deoxyglucose in rat brain: implications for estimates of kinetic parameters of deoxyglucose phosphorylation and transport between blood and brain.

The steady-state brain/plasma distribution ratios of [14C]deoxyglucose ([14C]DG) for hypoglycemic rats previously determined by measurement of DG concentrations in neutralized acid extracts of freeze-blown brain and plasma exceeded those predicted by simulations of kinetics of the DG model. Overestimation of the true size of the precursor pool of [14C]DG for transport and phosphorylation could arise from sequestration of [14C]DG within brain compartments and/or instability of metabolites of [14C]DG and regeneration of free [14C]DG during the experimental period or extraction procedure. In the present study, the concentrations of [14C]DG and glucose were compared in samples of rat brain and plasma extracted in parallel with perchloric acid or 65% ethanol containing phosphate-buffered saline. The concentrations of both hexoses in acid extracts of brain were higher than those in ethanol, whereas hexose contents of plasma were not dependent on the extraction procedure. The magnitude of overestimation of DG content (about 1.2-to fourfold) varied with glucose level and was highest in extracts isolated from hypoglycemic rats; contamination of the [14C]DG fraction with 14C-labeled nonacidic metabolites also contributed to this overestimation. Glucose concentrations in acid extracts of brain exceeded those of the ethanol extracts by less than 40% for normal and hypoglycemic rats.

Acids↗

PubMed2003

Effect of different sample pretreatment methods on the concentrations of excitatory amino acids in cerebrospinal fluid determined by high-performance liquid chromatography.

Using high-performance liquid chromatography (HPLC), the effect of different sample pretreatment methods on the concentrations of excitatory amino acids (EAAs, glutamate and aspartate) measured in cerebrospinal fluid (CSF) was investigated. The results showed that the measured values of glutamate and aspartate were constant when the samples were stored at -80 degrees C and then methanol was used for CSF deproteinization before assay; the values of glutamate (Glu) increased when 0.3 M perchloric acid was used for CSF deproteinization with the CSF subsequently being stored at -20 degrees C; the values of Glu changed when the samples were stored at -20 degrees C over 8 weeks with methanol subsequently being used for CSF deproteinization before assay. This reference data suggested that the CSF sample would be better stored at -80 degrees C. If the sample is stored at -20 degrees C over 8 weeks, the Glu values change with the storage time. If strong acidic reagents are used for precipitation of protein in the CSF sample and then stored at -20 degrees C, Glu values are abnormally increased. From this study, an accurate and sensitive reversed-phase high-performance liquid chromatographic method has been developed for anti-excitotoxicity therapy and thorough study of EAAs in a clinical setting.

Aspartic Acid↗

PubMed1995

Adult-onset hypothyroidism and the cerebral metabolism of (1,2-13C2) acetate as detected by 13C nuclear magnetic resonance.

The effects of adult-onset hypothyroidism on the metabolic compartmentation of the cerebral tricarboxylic acid cycle and the gamma-aminobutyric acid (GABA) shunt have been investigated by 13C nuclear magnetic resonance spectroscopy. Rats thyroidectomized as adults and age-matched controls were infused in the right jugular vein with unlabeled or (1,2-13C2) acetate solutions for 60 min. At the end of the infusion, the brains were frozen in situ and perchloric acid extracts were prepared and analyzed by 13C nuclear magnetic resonance and reverse-phase HPLC. Thyroidectomized animals showed a decrease in the incorporation of 13C from (1,2-13C2) acetate in cerebral metabolites and an increase in the concentrations of unlabeled glutamate and GABA. Computer-assisted interpretation of the 13C multiplets observed for the carbons of glutamate, glutamine, and GABA indicated that adult-onset hypothyroidism produced 1) a decrease in the contribution of infused (1,2-13C2) acetate to the glial tricarboxylic acid cycle; 2) an increase in the contribution of unlabeled acetyl-CoA to the neuronal tricarboxylic acid cycle; and 3) impairments in the exchange of glutamate, glutamine, and GABA between the neuronal and glial compartments. Despite the fact that the adult brain has often been considered metabolically unresponsive to thyroid hormone status, present results show metabolic alterations in the neuronal and glial compartments that are reversible with substitution therapy.

Acetates↗

PubMed1998

[Determination of sunscreen agents in cosmetic products by reversed-phase high performance liquid chromatography].

A method for quantitative determination of eleven sunscreen agents (benzophenone-4,p-amino-benzoic acid, salicylic acid, benzophenone-3,phenyl salicylate, 4-methylbenzylidene camphor, octyl dimethyl p-amino-benzoate, isopropyl dibenzoylmethane, butyl methoxydibenzoylmethane, octyl methoxycinnamate, octyl salicylate) in cosmetic products is described. It was based on a high performance liquid chromatographic separation under the condition of isocratic elution with a mixture solution of methanol-THF-water-70% perchloric acid (200:200:160:0.1) by using a column packed with 10 microns YWG-C15 and UV detection. The recoveries (n = 6) were 94.1%-101% and the relative standard deviations(n = 6) for all eleven sunscreen agents were less than 5%. In addition, the results of analysis of 30 samples out of 103 samples of commercial suntan cosmetics performed are reported in this paper.

Chromatography, High Pressure Liquid↗