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Results for “PERCHLORIC ACID”

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PubMed1975

Colorimetric and volumetric assays of colchicine in galenicals and in pharmaceutical preparations.

In the method described the amide group in the colchicine molecule is reduced with lithium aluminum hydride to the corresponding secondary amine. The latter is extracted with chloroform and then determined either colorimetrically by the copper dithiocarbamate reaction or volumetrically by dissolving in acid and titrating with sodium hydroxide or perchloric acid. The results were comparable with those obtained by the Egyptian Pharmacopoeia spectrophotometric method.

Amides↗

PubMed1987

[Comparative research on serum N-acetylneuraminic acid determinations in tumor diagnosis].

N-acetylneuraminic acid (NAN) is determined in supernatants of perchloric acid as well as in chloroform/methanol extracts (lipid bound sialic acid) from sera of tumour patients. Compared to patients with other diseases, we do not find fundamental differences. In patients suffering from kidney tumours, bronchial and gastric carcinomas, the NAN values of both extracts are distinctly outside the range of the reference values. In most cases, acid alpha 1 glycoprotein is found to be the cause of the NAN concentration.

Arthritis, Rheumatoid↗

PubMed1976

The development of a radioimmuno-assay for carcino-embryonic antigen with some applications. Clinical evaluation of carcino-embryonic antigen, I.

This paper, the first in a series devoted to the study of the clinical usefulness of estimations of carcino-embryonic antigen (CEA) in serum and urine, describes in detail a direct radioimmunoassay for CEA in serum and urine (a modified Egan technique, Egan, M.L. et al. (1972), Immunochemistry, 9, 289-299). A comparative study of the behaviour of CEA batches and anti-CEA antisera from different laboratories in the radioimmunoassay is presented. The incidence of increased serum CEA levels in healthy smokers was found to be related to smoking habits. Assays of CEA in serum obtained by the direct technique and the Hansen perchloric acid--zirconyl gel technique (Hansen, H.J. et al. (1971), Clin. Res. 19, 143-147) showed comparable results. Various problems affecting the assay of CEA in serum and urine are critically discussed, e.g. criteria for absorbing-out of anti-CEA antisera, identification of CEA, factors causing false CEA values, use of reference materials, acceptability of a strict cut-off level to indicate increased CEA levels, and factors governing the choice of antisera. In this connection we present a new approach which maintains a reliable and consistent cut-off level in follow-up studies. Evidence is presented that urinary CEA is heterogeneous and perchloric acid-unstable.

ABO Blood-Group System↗

PubMedDate not supplied

Differential electrolytic potentiometric determination of some amino acids in dosage forms.

The application of direct-current differential electrolytic potentiometry to the nonaqueous titration of amino acids was investigated. The basic character of amino acids in acetic acid was enhanced to permit their direct titration with perchloric acid. A pair of antimony electrodes was used as an indicating system. The shapes of the titration curves obtained were almost symmetrical with sharp peaks. The optimum current density for those titrations was found to be 1-2 microA/cm2. The procedure was applied successfully to the determination of certain amino acids in drug formulations, and the results were favorably compared statistically with those obtained by official methods.

Amino Acids↗

PubMed2026

Targeted Modulation of Abundant Proteins Enhances Proteomic Profiling of Ovarian Cancer Ascites: A Pilot Technical Workflow Comparison.

Ascites from ovarian cancer patients are increasingly recognized as a valuable biofluid for cancer research, as its protein composition reflects the disease state and may reveal biomarkers of treatment sensitivity and response. However, the detection of low-abundance proteins is hindered by the presence of highly abundant proteins such as albumin. In this study, we evaluated five protein preparation methods for their effectiveness in depleting high-abundance or enriching low-abundance proteins in ovarian cancer ascites. The Norgen (Nor), Minutes (Min), and Perchloric acid (PerCA) methods were based on abundant protein depletion, while the Urine (Uri) and Nanomics (Nano) kits focused on low-abundance protein enrichment. Processed samples were analyzed using label-free quantitative bottom-up proteomics by LC-MS/MS, followed by a bioinformatics assessment. Compared with undepleted ascites (UnD), Min, Nor, Nano, and PerCA increased protein identifications, whereas Uri produced profiles similar to those of UnD. Notably, PerCA and Nano enabled the identification of distinct protein subsets associated with cancer-related pathways, including immune responses and autophagy. PerCA enriched transmembrane and secreted immunomodulatory glycoproteins, whereas Nano enrichment primarily captured secreted, nuclear, and cytoplasmic soluble proteins. Overall, our results show that both high-abundance protein depletion and low-abundance enrichment improve ascites proteome coverage, each offering distinct advantages in identifying biologically relevant low-abundance proteins.

Female↗

PubMed1984

Measurement of alpha-keto acids in plasma using an amino acid analyzer.

A method for measuring keto acid concentrations in physiological fluids using an amino acid analyzer was developed. After preliminary deproteinization and removal of amino acids, reduction with sodium cyanoborohydride at 105 degrees C resulted in efficient conversion of the keto acids to their corresponding amino acids. In applying the technique to plasma samples, the use of MeOH for deproteinization was necessary to avoid the large losses of keto acids that occurred during precipitation of proteins with perchloric acid. The method was used to follow plasma ketoisocaproate concentrations in rat plasma after administration of leucine, and was sufficiently sensitive to detect concomitant changes in other branched-chain keto acid concentrations.

Amination↗

PubMed1992

Rapid and selective isolation of radiolabelled inositol phosphates from cancer cells using solid-phase extraction.

A method is described for rapid and selective determination of radiolabelled inositol phosphates in cancer cells using solid-phase extraction with Bond Elut strong anion-exchange minicolumns. The inositol phosphates IP1, IP2 and IP3 are selectively eluted with 0.05, 0.3 and 0.8 M ammonium formate-0.1 M formic acid, respectively. Cancer cells are extracted with 10% perchloric acid which is then neutralised prior to loading samples on to the minicolumns. Recovery is 54.1, 66.6 and 61.3% for IP1, IP2 and IP3 with between-day coefficients of variation of 7.6, 6.8 and 1.9%, respectively. When the method was applied to cancer cells high-performance liquid chromatographic analyses confirmed both the identity of the IP1, IP2 and IP3 fractions and showed that there was no detectable cross contamination of these inositol phosphates with each other.

Chromatography, High Pressure Liquid↗

PubMed1998

Achiral and chiral high-performance liquid chromatographic methods for clinafloxacin, a fluoroquinolone antibacterial, in human plasma.

Achiral and chiral HPLC methods were developed for clinafloxacin, a quinolone antimicrobial agent. For achiral assay, analytes were isolated from plasma by precipitating plasma proteins. Separation was achieved on a C18 column using an isocratic eluent of ion pairing solution-acetonitrile (80:20, v/v) at 1.0 ml/min with UV detection at 340 nm. The ion pairing solution was 0.05 M citric acid, 1.15 mM tetrabutylammonium hydroxide and 0.1% ammonium perchlorate. Inter-assay accuracy was within 4.9% with an inter-assay precision of 3.7% over a quantitation range of 0.025 to 10.0 microg/ml. For chiral assay, analytes were isolated from plasma by solid-phase extraction. Separation was achieved on a Crownpak CR(+) column using an isocratic eluent of water-methanol (88:12, v/v) containing 0.1 mM decylamine at 1.0 ml/min with UV detection at 340 nm. Perchloric acid was added to adjust pH to 2. Inter-assay accuracy was within 3.5% with a inter-assay precision of 5.4% over a quantitation range of 0.040 to 2.5 microg/ml.

Anti-Infective Agents↗

PubMed2001

Characterisation and quantification of medium chain and long chain triglycerides and their in vitro digestion products, by HPTLC coupled with in situ densitometric analysis.

The development of new and simple high performance thin layer chromatography (HPTLC) assays for the quantification of medium chain triglycerides (MCT, tricaprylin) and long chain triglycerides (LCT, triolein) and their lipolytic products, bile salts (BS) and phospholipids (PL) are described. Different classes of lipids (PL, BS, fatty acids, monoglycerides, diglycerides, and triglycerides) were separated on a single silica gel 60 HPTLC plate by Automated Multiple Development (AMD) methods using a Camag AMD 2. Post-chromatographic staining of long chain lipids (triolein, diolein, monoolein, and oleic acid), PL and BS with a solution of copper sulphate-phosphoric acid and medium chain lipids (tricaprylin, dicaprylin, monocaprylin, and caprylic acid) with a solution of ammonium molybdate-perchloric acid allowed visualisation of the lipids. Lipids were quantified by in situ spectrodensitometric measurements using a Camag TLC scanner 3. The intra- and inter-assay accuracy was between 83 and 115% and the assay was precise to within a CV of less than 20% over a range of 0.1-1 and 5-50 microg for long chain lipids and medium chain lipids, respectively. The methods have been employed to study the kinetics of triolein and tricaprylin lipolysis in an in vitro lipid digestion model commonly used to assess the digestibility of novel oral lipid-based formulations.

Chromatography, Thin Layer↗

PubMed1997

1H-Tetrazole as Catalyst in Phosphomorpholidate Coupling Reactions: Efficient Synthesis of GDP-Fucose, GDP-Mannose, and UDP-Galactose.

An improved procedure is described for the efficient and high-yield (76-91%) synthesis of nucleoside diphosphate sugars from the readily available nucleoside 5'-monophosphomorpholidate and sugar 1-phosphate in the presence of 1H-tetrazole. Comparative kinetic investigations by means of (31)P NMR spectroscopy with different additives (1,2,4-triazole, acetic acid, N-hydroxysuccinimide, 4-(dimethylamino)pyridine hydrochloride, perchloric acid) and mass spectrometric analysis suggest that tetrazole acts as an acid and as a nucleophilic catalyst in the pyrophosphate bond formation.

Journal Article↗

PubMed1999

Optimized procedure for the determination of antimony in lipid-rich environmental matrices by flow injection hydride generation atomic absorption spectrometry.

An analytical procedure for the reliable determination of Sb in digests of lipid-rich environmental matrices in the low ng l-1-range based on flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) has been developed. Prior to HG-AAS, aliquots (250 to 320 mg) of dry samples were mineralized with 3 ml nitric acid and 0.5 ml of each sulfuric and perchloric acids in open digestion vessels made of glassy carbon in a heating block. Procedure detection and quantification limits of a previously developed procedure for the determination of Sb in plant materials by FI-HG-AAS were decreased with respect to the lower Sb concentrations in animal tissues, the sensitivity of the instrumental response was increased, and the composition of the acid digestion mixture was re-optimized for lipid-rich samples. The accuracy and precision of the developed procedure was evaluated by the analysis of the two reference materials Bovine Liver 1577a and Pig Kidney CRM 186. These reference materials have been additionally spiked with appropriate amounts of Sb to obtain recovery data. The solution detection limit (3 sigma) in digested samples was 0.021 microgram l-1, the detection limit for the whole procedure based on the dry powders was 7 pg g-1, the method quantification limit for a reliable determination of Sb was 23 pg g-1. The reproducibility of repetitive measurements was 6.0% at 0.1 microgram Sb l-1 and 2.2% at 0.5 microgram Sb l-1. Calibration curves were linear from 0.05 to 3 micrograms Sb l-1. To demonstrate the suitability of the developed method, concentrations of Sb have been determined in pigeon eggs (approximately 2 ng Sb g-1), as well as in bream livers (approximately 4 ng g-1) and in deer livers (approximately 5 to 8 ng g-1) from animals living in remote and urban-industrialized areas of Germany, respectively.

Animals↗

PubMed1991

Improvement on the microdiffusion technique for the determination of ionic and ionizable fluoride in cows' milk.

Different microdiffusion techniques for the determination of ionic and ionizable fluoride in milk have been evaluated for measurement with a fluoride-selective sensor. This work culminated in a modified version of the hexamethyldisiloxane-acid diffusion technique where an increased amount of perchloric acid and sodium hydroxide seemed to be a prerequisite for accurate and precise results. The configuration of the fluoride-selective electrode was also modified by using an adapted microanalytical procedure to determine fluoride in small volumes (50 microliters each) and to avoid contamination between successive milk samples. The resultant procedure is free of interferences and is capable of measuring fluoride in milk at concentrations from 0.02 to 10.00 mg dm-3 with improved accuracy and precision compared with earlier work.

Animals↗

PubMed2000

Improved measurement of iodine in food samples using inductively coupled plasma isotope dilution mass spectrometry.

A new ICP-MS method for the determination of iodine in food samples is presented. The method makes use of a new miniature cyclonic spray chamber and a concentric glass nebulizer that is designed for low sample uptakes and is operated in a self-aspirating mode. As a consequence the wash-out was accelerated over conventional systems. This configuration allows the direct determination of iodine in mineralized solutions following digestion with nitric acid only. No strong oxidizing reagents such as perchloric acid or lengthy sample preparation were necessary to alter the chemical form of potentially volatile species. The isotope dilution technique using the long-lived isotope 129I was applied to obtain freedom from matrix effects. The present study reports on results for total iodine in selected nutritional and biological reference materials and makes a comparison with instrumental neutron activation analysis.

Food Analysis↗

PubMed1957

A chromatographic study of hydrolysis in the Feulgen nucleal reaction.

In a study on Feulgen hydrolysis of frozen-dried alcohol-fixed lily anthers, a chromatographic technique was developed to analyze the acid hydrolysate for some of the degradation products of nucleic acid. Hydrolysis was accomplished by 10 per cent perchloric acid at 20 degrees C., and a typical hydrolysis time-Feulgen intensity curve was obtained, with maximum staining occurring at 19 hours. Microphotometric measurements indicated that the amount of stain per nucleus was no different from amount in nuclei fixed and hydrolyzed by more conventional procedures. Uracil-containing material (from ribonucleic acid) was almost completely separated from thymine-containing material (deoxyribonucleic acid) of tissue sections by acid treatment for 1(1/2) hours. Adenine (purines), as the base, was effectively all removed from the deoxyribonucleic acid at the time of optimum hydrolysis. Detectable amounts of thymine-containing material appeared in the hydrolysate shortly after the onset of hydrolysis; and the amount increased rapidly with increased hydrolysis time. At the time of optimum hydrolysis approximately two-thirds of the total deoxyribonucleic acid thymine was lost. The removal of these thymine-containing fragments was linear with respect to time during the first 24 hours and occurred at a relatively high rate. Removal after 24 hours was also linear but was at a markedly lower rate. These results would suggest that two kinds of deoxyribonucleic acid exist in lily anthers; an acid-labile fraction amounting to approximately three-fourths of the total, and an acid-resistant fraction making up the remainder. In the Feulgen procedure much of the labile fraction is lost by the time of optimum hydrolysis and is not stained; most of the stable fraction remains in the tissue and is stained. In light of these findings the use of the Feulgen method as a means of determining cytochemically relative amounts of deoxyribonucleic acid in nuclei by measuring their Feulgen dye content was discussed.

Adenine↗

PubMed1982

Simultaneous determination of serotonin, 5-hydroxindoleacetic acid, 3,4-dihydroxyphenylacetic acid and homovanillic acid by high performance liquid chromatography with electrochemical detection.

A rapid and highly sensitive procedure for simultaneous determination of serotonin, 5-hydroxyindoleacetic acid, 3,4-dihydroxyphenylacetic acid and homovanillic acid is described. After precipitation of proteins with perchloric acid the samples are applied directly to a high performance liquid chromatograph, with electrochemical detection. As little as 20 pg of serotonin, 5-hydroxyindoleacetic acid, and 3,4-dihydroxyphenylacetic acid and 200 pg of homovanillic acid can be detected. One chromatographic run requires less than 10 min.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2001

NMR spectroscopic analysis of rat brain development: in vitro proton and carbon studies of whole tissue and its phospholipid fraction.

The developmental patterns of the rat brain at several postnatal time points were investigated in Folch (chloroform-methanol) extracts. The chloroform- (lipid-containing) and water-soluble (cytosolic) fractions of whole-tissue extracts and the phospholipid fraction separated from the organic fraction by chromatography were analysed by means of high-resolution (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy. Analysis of the cytosolic fraction showed the changing patterns of several brain metabolites during postnatal maturation, in full agreement with data obtained from perchloric acid extracts. (1)H NMR spectroscopy of the phospholipid fraction allowed for quantitative evaluation of fatty acid acyl chain length, mean unsaturation and mean polyunsaturation. It was found that both mean unsaturation and polyunsaturation are lower in adult brain phospholipids than during the first 3 postnatal weeks. (13)C NMR spectroscopy of the same fraction showed that the molar percentage of C(18) fatty acids (oleic, linoleic, linolenic) in brain phospholipids is similar at all the investigated time points. These results indicate that the combination of Folch extraction with simple chromatographic procedures and NMR analysis yields useful data to define the chemical maturation of the brain.

Animals↗

PubMed1978

Measurement of plasma adenosine 3',5'-monophosphate.

Currently used methods for plasma cAMP measurements are either tedious (chromatographic preparation of sample) or potentially inaccurate (direct assay of plasma samples). A rapid, simple, and accurate competitive binding assay for plasma cAMP, which does not require chromatographic preparation of the sample, has been developed. This procedure prevents destruction of plasma cAMP by utilizing both theophylline and EDTA in the collection of the blood sample. Human plasma contains variable amounts of cAMP-binding activity which interfere with the measurement of cAMP by the standard competitive binding assay. Our assay procedure removes this binding activity by precipitation of plasma proteins with perchloric acid. The normal fasting value (+/- SD) of plasma cAMP using this technique is 17.6 +/- 4.3 pmol/ml, which is identical to values obtained by methods utilizing chromatographic purification of samples (18.3 +/- 3.0). The fasting plasma cAMP of patients with hyperparathyroidism is normal (16.2 +/- 3.4), but patients with maturity-onset diabetes mellitus have fasting values significantly below normal (12.3 +/- 2.4).

Animals↗

PubMed1979

Intrinsic ADP-ribose transferase activity versus levels of mono(adp-ribose)protein conjugates in proliferating Ehrlich ascites tumor cells.

Transition of proliferating Ehrlich ascites tumor cells (3 days after transplantation) to the non-proliferating status (8--14 days after transplantation) was associated with an increase in total mono (ADP-ribose) protein conjugates. This increase was largely confined to the NH2OH-resistant subfraction. When the amounts of mono-(ADP-ribose) conjugates from 20% trichloroacetic acid precipitates were compared with those from 5% perchloric acid precipitates, no significant differences were seen. This fact excludes histone H1 as a major mono (ADP-ribose) acceptor in vivo in these cells. Transition to the resting state was also associated with a small decrease in NAD levels, and with no significant changes of total ADP-ribose transferase activity. However intrinsic ADP-ribose transferase activity as expressed in permeabilized cells was increased, being correlated with the changes in the level of the NH2OH-resistant mono (ADP-ribose) protein conjugates. This shows that alterations in intrinsic transferase activity may, in general, indicate similar alterations in major subfractions of ADP-ribose conjugates. Intrinsic ADP-ribose transferase activity exhibited an inverse relationship to ornithine decarboxylase activity.

Adenosine Diphosphate Ribose↗