bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chromatographic techniques in inborn errors of metabolism
Authors: Lehotay Denis C. 
Published: May 2005

AbstractChromatography has played a pivotal role in the advances made during the last 30 years in our knowledge of inborn errors of metabolism. This review discusses the application of some of these techniques to the analysis of organic acids and acylcarnitines. The separation of organic acids needed a comprehensive approach that would permit all of the many organic acids present in urine or other complex mixtures to be extracted, analysed and identified in a single run. This required analytical methods of great resolving power, wide linear range and universal detectors such as gas chromatography (GC), or GC coupled with mass spectrometry. Sample preparation was another problem that has been tackled by a variety of approaches. Organic solvents have been employed widely for the extraction of organic acids from physiological fluids. Unfortunately, recoveries of the different organic acids by this method are sometimes less than quantitative and variable depending on the compound. Other methods, such as the use of DEAE‐Sephadex columns, have the advantage of resulting in close to 100% recoveries, but are more tedious. Liquid partition chromatography on short silicic acid columns has also been recommended as a useful clean‐up step prior to GC, permitting both the identification and quantitation of organic acids in urine, plasma or amniotic fluid. Although many derivatization procedures have been used to prepare organic acids for gas chromatography, the most common is trimethylsilylation. Oxo acids are usually reacted with one of several commonly used reagents to form oximes. GC analysis of organic acids was initially done using packed columns with methylsilicone‐based, non‐polar stationary phases. In recent years most laboratories have switched to the commercially available, bonded‐phase capillary columns. Some authors have recommended the use of two columns of slightly differing polarities to improve the reliability of identification without mass spectrometry. Carnitine and acylcarnitines are substances whose measurement may yield useful diagnostic information about inborn errors and about the basic biochemical mechanisms of disease. While free carnitine is usually measured by a radioenzymatic assay, the separation of acylcarnitines requires paper chromatography or high performance liquid chromatography. The identification of various acylcarnitines following separation has been accomplished by mass spectrometric methods. Another technique relies on gas chromatographic identification of the acyl groups liberated following alkaline hydrolysis. Recently, liquid chromatography/mass spectrometry has also been utilized to separate and identify the various acylcarnitines present in urine and other biological samples.
Determination of short‐chain fatty acids in equine caecal liquor by ion exchange high performance liquid chromatography after solid phase extraction
Authors: Horspool L. J. I. , McKellar Q. A. 
Published: May 2005

AbstractA high performance liquid chromatography (HPLC) method was developed for the determination of seven short‐chain fatty acids in equine caecal liquor. Samples were cleaned up on a Sep‐pak (C18) cartridge, and the analyte was eluted from the extraction cartridge and filtered through a 0.45 μm cellulose nitrate filter. The analyte was chromatographed by ion exchange HPLC. Detection was by UV at 210 nm. Recovery from phosphate buffer (0.05 M, pH 7.0) and equine caecal liquor was 76.95% (lactic), 76.76% (acetic), 84.40% (propionic), 89.35% (isobutyric), 88.73% (butyric), 80.33% (isovaleric) and 72.61% (valeric). The limit of detection of the short‐chain fatty acids in phosphate buffer was 0.00006 M (lactic), 0.0001 M (acetic), 0.0002 M (propionic), 0.0001 M (isobutyric), 0.0002 M (butyric), 0.0002 M (isovaleric) and 0.0003 M (valeric). The specificity and sensitivity of this method was sufficiently high to allow the characterization of the pattern of these short‐chain fatty acids in equine caecal liquor following intravenous administration of oxytetracycline at the recommended dose rate in a pony.
Application of photodiode array detection and fast atom bombardment mass spectrometry for the identification of the arginine residue in neuropeptides
Authors: Silberring Jerzy , Nyberg Fred 
Published: May 2005

AbstractChemical derivatization by phenylgyoxal (PGX) was applied to the identification of arginine in the neuropeptides dynorphin A (1–6) and substance P. The obtained products were separated on a short reversed phase C18 column and analysed on‐line with the photodiode array UV technique. The selective attachment of a chromogenic molecule into the arginine residue resulted in significant change in the absorbance spectra around 250 nm, depending on the number of PGX molecules attracted. Further analysis employed fast atom bombardment mass spectrometry (FAB MS) and C‐terminal sequencing for detailed verification of the derivatives formed during modification with PGX. The results clearly demonstrated that the photodiode array technique, when combined with chemical modification of certain amino acids, provides new possibilities for the analysis of peptide structures.
Disopyramide analysis using REMEDi: Comparison with EMIT and conventional high performance liquid chromatographic methods
Authors: Patel V. , McCarthy P. T. , Flanagan R. J. 
Published: May 2005

AbstractREMEDi (Rapid EMErgency Drug identification; Bio‐Rad) is an automated high performance liquid chromatographic (HPLC) system designed to detect, identify and measure a range of basic and neutral drugs in 0.5‐1.0 mL of urine or plasm/serum. We have evaluated REMEDi in the analysis of the antiarrhythmic drug disopyramide in patient samples. The specimens were also analysed by a conventional HPLC method, based on solvent extraction and UV detection (254 nm), and by EMIT. There were good correlations between the results obtained with each method (r = 0.91 or greater). REMEDi gave a lower mean result than EMIT [means±SD (m/L): REMEDi 2.64±1.10, EMIT 3.14±1.51; t = 4.0, p<0.01; n = 25], but there were no other significant differences in mean results. The principal disopyramide metabolite, mono‐N‐desalkyldisopyramide, did not interfere in any method. Clearly REMEDi can be used for therapeutic drug monitoring of disopyramide provided enough sample is available.
High performance liquid chromatography of spermidine and spermine using a postcolumn reactor of immobilized polyamine oxidase (Aspergillus terreus) Followed by Electrochemical Detection
Authors: Watanabe Noriyuki 
Published: May 2005

AbstractA highly sensitive and selective method for the determination of spermidine and spermine has been developed. A polyamine oxidase (Aspergillus terreus) immobilized column was used as a postcolumn reactor. The detection limit was 0.2 pmol/injection for both spermidine and spermine with a linear range of three orders of magnitude.
Determination of panaxadiol and panaxatriol in ginseng and its preparations by capillary supercritical fluid chromatography (SFC)
Authors: Yun‐hua Li , Xiu‐lu Li , Lan Hong , Jin‐yao Liu , Mei‐Yi Zhang 
Published: May 2005

AbstractCapillary supercritical fluid chromatographic (SFC) method has been developed for the determination of panaxadiol and panaxatriol in ginseng and its preparations. 0.1 g ginseng or an appropriate amount of its preparations was hydrolysed by 15% H2SO4 in an ethanol: water (1:1 v/v) solution for 4 h followed by 15% NaOH for 0.5 h. The mixture was extracted by cyclohexane. The cyclohexane extracts were purified by a partition column and concentrated by an adsorption column and then analysed by SFC. Methyltestosterone was used as the internal standard.
Simultaneous determination of paraquat and diquat in serum using capillary electrophoresis
Authors: Tomita Masafumi , Okuyama Toshiko , Nigo Yayoi 
Published: May 2005

AbstractThe use of capillary electrophoresis for simultaneous separation and detection of the two bipyridylium herbicides, paraquat and diquat, was investigated. Both herbicides were extracted from fortified sera with disposable ODS‐silica cartridges. Separation was carried out using a capillary tube (50 μm i.d., 750 mm) of fused silica containing 10 mM glycine–HCl buffer (pH 3.0), 40 mM NaCl and 20% methanol as the carrier. Paraquat and diquat were completely separated in 10 min at an applied potential of 20 kV. On‐column UV monitoring allowed detection of both herbicides simultaneously. The assay sensitivity was 0.05 μg/mL (signal‐to‐noise ratio, 2:1), which probably increases with increase in the sample volume of serum. Analytical recovery of both herbicides added to serum was about 97% at concentrations of 0.5–2.0 μg/mL.
High performance liquid chromatographic strategy suitable for the analysis of exopolysaccharides extracted from pathogenic bacteria
Authors: Radin Livio , Sivori Simona , Eftimiadi Costantino , Lucarelli Claudio 
Published: May 2005

AbstractA high performance liquid chromatographic (HPLC) method has been developed to permit the rapid comparison of acidic polysaccharides of diverse compositions and the sensitive determination of their constituents. It is based on two combined analyses of the polysaccharide hydrolysates—a separation of the released compounds by ion‐moderated partition chromatography with UV detection at two wavelengths and a separation of the sugar dansylhydrazine derivatives by reversed phase chromatography. The former permits identification and quantitation of uronic and carboxylic acids, the latter permits more sensitive and specific determination of the neutral aldoses. Some bacterial exopolysaccharides have been used to demonstrate the validity of this HPLC procedure for the chemical characterization of uronic acid‐containing polysaccharides. This method appears to be useful for studying capsular polysaccharides, which are involved in the evasion of phagocytosis by pathogenic bacteria.
Quantitative determination of CGS 18102A, a new anxiolytic, in human plasma using capillary gas chromatography/mass spectrometry
Authors: Leal M. , Hayes M. J. , Powell M. L. 
Published: May 2005

AbstractCGS 18102A is a novel hexahydrobenzopyranopyridine that has a mixed pharmacological profile of 5‐HT‐1A agonist and 5‐HT‐2 antagonist properties. Based upon these mechanisms, the compound is predicted to have anxiolytic efficacy with possible efficacy in depression. Preclinical studies in the rat have shown the drug to be well absorbed and extensively metabolized. Because of the anticipated low plasma levels in humans a gas chromatography/mass spectrometry (GC/MS) analytical method has been developed and validated to determine plasma concentrations of CGS 18102A in early clinical studies. The method utilizes CGS 18416A as the internal standard. Samples (1 mL) were extracted with pentane:ethyl acetate (75:25, v:v). Extracts were then concentrated and analysed directly by GC/MS. Separation was accomplished on a methylsilicone capillary column (30 m × 0.32 mm i.d.). GC/MS was carried out under positive ion ammonia CI conditions, with selected ion monitoring of the [M + H]+ ions (m/z = 262 and 248) for CGS 18102A and CGS 18416A, respectively. The method was successively applied to the analysis of clinical samples from an ascending multidose safety and tolerability study conducted in six normal healthy male volunteers.
A Selective HPLC/RIA for dexamethasone and its prodrug dexamethasone‐21‐sulphobenzoate sodium in biological fluids
Authors: Hochhaus Günther , Hochhaus Renate , Werber Gisela , Derendorf Hartmut , Möllmann Helmut 
Published: May 2005

AbstractA combined high performance liquid chromatography/radioimmunoassay procedure is described for the simultaneous determination of dexamethasone (DEX) and its prodrug dexamethasone‐21‐sulphobenzoate sodium (DSS) in plasma. After precipitation of the plasma proteins by acetonitrile, the protein‐free supernatant was injected onto a C18 reversed phase liquid chromatographic system and DSS‐ and DEX‐containing fractions were collected. Hydrolysis of DSS by 0.01 N NaOH, followed by fractions extraction of both hydrolysed DSS and DEX fractions with ethyl acetate allowed the use of a dexamethasone‐specific radioimmunoassay for the selective determination of both compounds. The method is accurate and reproducible (intraday variability for DSS and DEX<6%, interday variability for DEX 14%), allowing quantification of DEX and DSS as low as 0.3 ng/mL and 0.7 ng/mL, respectively.
Measurement of ascorbic acid and dehydroascorbic acid in mammalian tissue utilizing HPLC and electrochemical detection
Authors: Schell Debra A. , Bode Ann M. 
Published: May 2005

AbstractReliable measurement of the reduced and oxidized forms of ascorbic acid (AA) is challenging because they are highly reactive and unstable compounds. Detection of small amounts of AA and dehydroascorbic acid (DHAA) is essential for determining the biochemical function of the vitamin. While a variety of techniques exist for measurement of AA with detection limits in the millimolar range, a need exists for highly reliable assessment of picomolar levels of AA and DHAA in tissues. The present study presents a method for measuring AA and DHAA that combines high performance liquid chromatography with the advantages and increased detection limits and selectivity available with coulometric electrochemical detection. The difference between AA and „total AA”︁ in tissue samples gives an assessment of DHAA concentration. Verification of the reliability of assay is by the successful linear recovery of exogenously added AA and DHAA in tissue homogenate. Optimal conditions for reducing DHAA in tissue samples include a pH of 7.2, reaction time of 10 min, reaction temperature equal to room temperature, and a 10 mM concentration of the reducing agent, β‐mercaptoethanol. AA and DHAA are measured in several mammalian tissues using the method presented.
Chiral separation of amines by high‐performance liquid chromatography after tagging with 4‐(N,N‐dimethylaminosulphonyl)‐7‐(2‐chloroformylpyrrolidin‐1‐yl)‐2,1,3‐benzoxadiazole
Authors: Toyo'oka Toshimasa , Liu Yi‐Ming , Jinno Hideto , Hanioka Nobumitsu , Ando Masanori , Imai Kazuhiro 
Published: May 2005

AbstractChiral tagging reagents, 4‐(N,N‐dimethylaminosulphonyl)‐7‐(2‐chloroformylpyrrolidin‐1‐yl)‐2,1,3‐benzoxadiazole (R(+)‐DBD‐Pro‐COCl and S(−)‐DBD‐Pro‐COCI), react with mirror image enantiomers of amines to produce corresponding diastereomers in the presence of pyridine as a catalyst. The maximal excitation and emission wavelengths of the resulting diastereomers were ca. 450 nm and 560 nm, respectively. The diastereomers derived from some aliphatic amines were resolved by a reversed‐phase chromatography with water–acetonitrile or normal‐phase chromatography with n‐hexane–ethyl acetate as the eluent. The reactivities of both enantiomers of DBD‐Pro‐COCI to chiral amines were almost comparable, whereas a slight difference of fluorescence intensity was observed with S(−)‐DBD‐Pro‐COCI. When S(−)‐DBD‐Pro‐COCI was used as the derivatization reagent, amines corresponding to S‐configuration were eluted faster than R‐configuration. The opposite elution order was obtained with the use of R(+)‐DBD‐Pro‐COCI, instead of S(−)‐DBD‐Pro‐COCI. The Rs values obtained from 1‐cyclohexylethylamine (CEA) having aliphatic ring structure was larger than those of amines (1‐(1‐naphtyl)ethylamine (NEA) and 1‐phenylethylamine (PEA)) having aromatic ring structures.
Reversed‐phase HPLC separation and chromatographic–spectral characterization of 17β‐(2′‐thiazolyl)androst‐5‐en‐3β‐ols and their acetates
Authors: Drašar P. , Urbanský M. 
Published: May 2005

AbstractSimple isocratic HPLC separation of a series of thiazolyl steroids with the 17β‐2′ linkage is described. The chromatographic and spectral characterization utilizes both on‐the‐fly UV spectral maxima and absorbances changes.
A Novel electrophilic reagent, 4‐(N‐chloroformylmethyl‐N‐methyl)amino‐7‐N,N‐dimethylaminosulphonyl‐2, 1,3‐benzoxadiazole (DBD‐COCI) for fluorometric detection of alcohols, phenols, amines and thiols
Authors: Imai Kazuhiro , Fukushima Takeshi , Yokosu Hirochika 
Published: May 2005

AbstractA novel electrophilic reagent for alcohols, phenols, amines and thiols, 4‐(N‐chloroformylmethyl‐N‐methyl)amino‐7‐N,N‐dimethylaminosulphonyl‐2, 1, 3‐benzoxadiazole (DBD‐COCI) was synthesized. The reactivity of the reagent to these nucleophiles was studied using high‐performance liquid chromatography (HPLC) with precolumn derivatization techniques.DBD‐COCI reacted in benzene solution at the room temperature or 60°C with androsterone (a representative of hydroxyls), (−)‐mandelic and D,L‐lactic acid (hydroxy acid), estrone (phenol), benzylamine (primary amine), phenetidine (aromatic amine) and α‐mercapto‐N,2‐naphthylacetamide (thiol) to give fluorescent products bearing fluorescence wavelengths at between 543 nm and 555 nm (excitation at between 437 nm and 445 nm). The base catalyst, quinuclidine was required to complete the reaction with the nucleophiles except aromatic amines. The reaction solution was subjected to a reversed phase HPLC and the detection limits of the derivatives were at the femto mol range on column.
Polymeric reagents for derivatizations in micellar electrokinetic chromatography
Authors: Szulc Michael , Krull Ira S. 
Published: May 2005

AbstractA polymer immobilized o‐nitrobenzophenone reagent was prepared for analysis of amine drugs in micellar electrokinetic chromatography (MEKC). A model compound, propylamine, was used to characterize the reagent's performance in MEKC. Derivatizations were performed on the CE instrument with reagent in the sample vial. The yielded derivative was directly sampled from the reaction mixture, and directly injected onto the MEKC system. The derivatization reagent was also applied to the derivatization of n‐alkyl amine mixtures and amino acids. The method was validated for adamantanamine in urine and amino acids. The method was validated for adamantanamine in urine and in plasma by single‐blind spike analysis. Precisions and accuracies for all samples were less than 6.0% for urine samples and 10% for plasma samples. The procedure was a direct injection technique requiring minimal sample preparation for the analysis of drugs in biofluids.
Determination of chloral hydrate and its metabolites (trichloroethanol and trichloracetic acid) in human plasma and urine using electron capture gas chromatography
Authors: Humbert L. , Jacquemont M. C. , Leroy E. , Leclerc F. , Houdret N. , Lhermitte M. 
Published: May 2005

AbstractCapillary gas chromatography with electron capture detection is described for the quantification of chloral hydrate (CH) and is metabolites trichloroethanol (TCE) and trichloroacetic acid (TCA) in 0.1–1 mL of plasma samples. The method, with 2,2′‐dichloroethanol (DCE) as internal standard, involved extraction of chloral hydrate and trichloroethanol with diethyl ether and methylation of trichloroacetic acid with 3‐methyl‐1‐tolyltriazene (MTT), followed by diethyl ether extraction. The method has a detection limit of 5 ng/mL for CH and TCE and 10 ng/mL for TCA and also allows the determination of TCE‐glucuronide in 0.1–1 mL of plasma samples. It exhibits good linearity and precision. The method was applied to samples of plasma from a neonate after a single dose of 40 mg/kg of chloral hydrate and from an adult after a single dose of 6.25 mg/kg.
Gas chromatographic determination of enantiomers as diastereomers following pre‐column derivatization and applications to pharmacokinetic studies: A review
Authors: Srinivas Nuggehally R. , Shyu Wen Chyi , Barbhaiya Rashmi H. 
Published: May 2005

AbstractThe introduction of chiral chromatographic methods has revolutionized the art of separationand quantitation of chiral drugs in biological fluids. A large number of chiral derivatization reagents for various funtional grups are available commercially. Therefore, Pre‐column derivation methods have become attractive and simple for the gas chromatographic assays in biologcal fluids. The intent of this article is to review the pre‐column chiral derivatization reagents employed in gas chromatographic separations and analyses of enantiomers. A discussion of numerous procedures necessary to develop a quantitative gas chromatographic assay method for drug enantiomers is presented. In this regard, quantitative gas chromatographic assays based on this approach have been applied to investigate the stereoselective pharmacokinetics of several chiral drug such as fenfluramine, norfenfluramine, methylphenidate, etodolac, propranol, suprofen and methoxyphenamine.
Enantiomeric separation and sensitive determination of D, L‐amino acids derivatized with fluorogenic benzofurazan reagents on pirkle type stationary phases
Authors: Fukushima Takeshi , Kato Masaru , Santa Tomofumi , Imai Kazuhiro 
Published: May 2005

AbstractThe enantiomeric separations of D, L‐amino acids derivatized with fluorogenic reagents, 4‐fluoro‐7‐nitro‐2,1,3‐benzoxadiazole (NBD‐F), 4‐(N,N‐dimethylaminosulphonyl)‐7‐fluro‐2,1‐3,‐benzoxadiazole (DBD‐F) and 4‐aminosulphonbly‐7‐fluoro‐2,1,3‐ benzoxadiazole (ABD‐F) by high‐performance liquid chromatography (HPLC) ON various Pirkle type chiral stationary phases (CSPs, Sumichiral OA series) with citric acid in methanol as a mobile phase were studied. Since the least retention and no separation was observed for the derivatives of racemic phenylalanine methyl‐ester,‐amide and a drug without an α‐carboxyl group, the carboxylic acid group of the amino acid derivatives seemed to contribute to the enantioselective fixation of the derivatives through hydrogen bonding on the N‐acyl‐amino acid amide moiety of the CSP. The enantioselective retention of the derivatives was attained through the (S) or (R) configuration of valine, phenylglycine, naphthylglycine, naphthylethylamine or the tert‐leucine moiety in the CSP. The 2, 1, 3‐benzoxadazole (benzofurazan) moiety in the derivatives helps the effective fixation of the derivatives through a π‐πinteraction with an aromatic moiety such as a 3, 5‐dinitrophenyl group in the Pirkle type chiral stationary phases.D‐Amino acids in biological samples were easily determined utilizing the present derivatization with NBD‐F, enantiomeric separation and fluorometric detection (530 nm em/470nm ex) following deproteinization of biological samples (serum or brain homogenate) with methanol and centrifugation. The applications of the method were clearly demonstrated by the following results; D‐Ala was detected in sera of healthy volunteers at a level of 0.48‐3.10μM. D‐Lys was found in the serum of a patient with myeloma and requiring renal dialysis, and D‐Ser was found in rat and bovine cerebrum. Peak identification was performed by use of different types of stationary phases especially those bearing the opposite configuration to that of the chiral centre.