bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of capillary electrophoresis for thalassaemia screening
Authors: Law Hai‐Yang , Ng Ivy , Ong Joyce , Ong Choon‐Nam 
Published: May 2005

AbstractThis paper describes the use of high‐performance capillary electrophoresis (HPCE) for screening of thalassaemias. Preparation of globin was performed by adding 1mL of haemolysate to 20 volumes of cold acidified acetone. Separation of globins was accomplished in a 25 mM disodium phosphate buffer at pH 11.8 using an uncoated capillary column of 50 cm × 75 μm (i.d.). Distinct peaks of alpha, beta and gamma were resolved within 6min. The coefficient of variations for within‐day and between‐day runs were 4.7% and 6.37% respectively. Using this simple and rapid procedure up to 30 specimens could be analysed in a single day. This method appears to be reliable and can be used for mass screening of various haemoglobinopathies.
Separation of reducing monosaccharides by capillary zone electrophoresis
Authors: Qi Li , Zhu Yichuan 
Published: May 2005

AbstractThe separation of reducing monosaccharides derived from glycosidoproteins and glycolipids by capillary zone electrophoresis (CZE) is dependent on the pH and concentration of the borate buffer. Five saccharides were completely separated in a fused silica capillary tube (50 μm i.d., 65 cm) containing 50 mM borate buffer (pH 10.5) as carrier, with high resolution, at an applied potential of 20 kV after the reducing saccharides were derivatized with 1‐naphthylamine. On‐column UV (254 nm) monitoring allowed quantitation of these saccharides at least in the concentration range of 10–100 mM in reaction solution. This method was applied to the determination of the monosaccharides composition of various carbohydrate materials to demonstrate its usefulness.
Improved resolution of tryptic digest fragments from haemoglobin variants using phytic acid in free zone capillary electrophoresis
Authors: Okafo George N. , Perrett David , Camilleri Patrick 
Published: May 2005

AbstractCapillary electophoresis can be applied to the rapid characterization of tryptic digests of proteins. The addition of phytic acid to the separation buffer was found to improve resolution considerably when the technique was applied to differentiate between tryptic digests derived from variant haemoglobins. Moreover, analysis time was of the order of 15 min, which is considerably shorter than that obtained using gradient reversed‐phase high‐performance liquid chromatography or two‐dimensional paper chromatography–electrophoresis.
Measurement of amiloride in airway surface liquid utilizing HPLC and fluorescence detection
Authors: Selinger Krzysztof 
Published: May 2005

AbstractA high‐performance liquid chromatographic method for the determination of amiloride in airway surface liquid is described. It involves extraction of the drug with methanol from filter paper on which the sample is absorbed and chromatography on a Zorbax Rx column; the mobile phase is 25% acetonitrile in 0.05 M phosphate buffer; detection by fluorescence at 360/420 nm. Triamterene is used as an internal standard. The range of the assay is 2.0–2033.4 ng/sample, with adequate precision and accuracy. A power curve y = axb best describes the relationship between the peak‐height ratio and concentration. Recovery of amiloride is non‐linear, probably due to an adsorption process. Accuracy of the assay at lower amounts may be affected by the choice of filter paper a well as by presence of endogenous plasma components. The assay was used to measure amiloride amount in airway surface liquid after administration of 2.5 and 4.5 mg of nebulized amiloride.
A quantitative analytical method for the determination of a new thromboxane synthetase inhibitor (CGS 22652) in human plasma using high performance liquid chromatography
Authors: Stelling M. S. , Maniara W. M. , Powell M. L. 
Published: May 2005

AbstractA quantitative analytical method for the determination of a new thromboxane synthetase inhibitor (CGS 22652) in human plasma has been developed using high performance liquid chromatography (HPLC). The drug and internal standard (CGS 23298) were extracted with methylene chloride at pH 4.8. Separations were achieved by reversed phase chromatography using a mobile phase consisting of acetonitrile: 0.01M citrate/phosphate buffer (pH 3.5): methanol: tetrahydrofuran (45:45:9:1, v/v/v/v/), on a 5 μm C18 column at a flow rate of 1.0 mL/min. Plasma standard curves were linear from 50 to 2000 ng/mL, with recovery of the drug being greater than 94% at all concentrations. The method was validated over a concentration range of 50 to 2000 ng/mL, with a limit of quantification of 50 ng/mL.The method was successfully applied to the analysis of clinical samples from a single‐dose safety and tolerability study conducted in healthy male volunteers.
A quantitative analytical method for the determination of a new anxiolytic (CGS 19480A) in human plasma using high performance liquid chromatography
Authors: Stelling M. S. , Maniara W. M. , Powell M. L. 
Published: May 2005

AbstractA sensitive and specific analytical method has been developed for the determination of a new anxiolytic (CGS 19480A) in human plasma using high performance liquid chromatography (HPLC). The drug and internal standard (CGS 18102A), were extracted with hexane at pH 7. Separations were achieved by reversed phase chromatography on a Nucleosil 5 C18 column at a flow rate of 1.0 mL/min. The mobile phase consisted of acetonitrile: 0.01 M phosphate buffer (pH 7): methanol (51:35:14, v:v:v), where the final pH of the mobile phase was adjusted to 4.0 using 85% phosphoric acid. Plasma standard curves were linear from 5.0 to 500 ng/ml, with recovery of the drug being greater than 95% at all concentrations. The method was validated over a concentration range of 5.0 to 500 ng/mL with a limit of quantification of 5.0 ng/ mL.The method was successfully applied to the analysis of clinical samples from a single‐dose safety and tolerability study conducted in six healthy male volunteers.
Simultaneous determination of p‐aminobenzoic acid and its metabolites in urine by high performance liquid chromatography
Authors: Kastel Rudolf , Rosival Ivan , Blahovec Jan 
Published: May 2005

AbstractWe developed a new HPLC method for the determination of p‐aminobenzoic acid (PABA) and its metabolites (p‐aminohippuric acid, N‐acetyl‐p‐aminohippuric acid, N‐acetyl‐p‐aminobenzoic acid) in urine. As the internal standard m‐hydroxybenzoic acid was used. In the isocratic elution the mobile phase consisted of methanol and 0.02 M. ammonium acetate (20:80 v/v, pH 4.0). The separation was carried out on the C18, reversed‐phase column, particle size 5 μm. The separated components were detected at 280 nm. The method can be used in the assessment of the response of pancrease (secretion of digestive enzymes) to soya feeding as well as in the diagnosis of the exocrine pancreatic diseases of animals.
A sensitive detection method for peptide using 4‐fluoro‐7‐nitrobenozo‐2‐oxa‐1,3‐diazole and its application to measure prolyl endopeptidase activity
Authors: Yoshinaga Koji , Kobayashi Naomi , Nagatani Yasunori , Tanaka Yoshiaki , Ikeda Yugo 
Published: May 2005

AbstractA Measuring method sensitive to prolyl endopeptidase (EC 3.4.21.26, PEP) activity using native peptides (Arg‐Vasopressin or substance P) as substrates was established. The investigation of three different derivatization reagents, Which had been developed for an amino acid analysis, demonstrated that 4‐fluoro‐7‐nitrobenzo‐2‐oxa‐1,3‐diazole (NBDF) was the most suitable for the detection of Arg‐Gly‐NH2, which was released from Arg‐vasopressin by PEP. Arg‐Gly‐NH2 was reacted with NBDF at 65°C for 5 min at pH 7.6 and the reaction mixture was analysed by HPLC on a reverse‐phase column by monitoring the gluorescence intensity. The detection limit was 1 picomol per injection and the linear standard calibration curve could be constructed in the range of 1 to 100 picomol per injection with a 3.0% relative standard deviation. This sensitive detection method for peptide was applied to the measurement of PEP activity Using Arg‐vasopressin as a substrate and 1 × 10−3 unit of PEP activity was detectable. This method was also applicable to the measurement of PEP activity Using subsytance P as a substrate by detecting the derivative of its fragment peptide (Arg‐Pro‐Lys‐Pro).
Degradation of organophosphorus and carbamate pesticides in soils—HPLC determination
Authors: Thapar Sangita , Bhushan Ravi , Mathur R. P. 
Published: May 2005

AbstractBest conditions suited for the extraction and trace analysis of dimethoate, malathion, methyl‐parathion, carbaryl, carbendazim and carbofuran in soils, using HPLC, were established, Theis was followed by studies related to persistence of residues in different soils, Half‐life and take for 95% dissipation were determined in each case, Higher Ph, moderate mosture and hihg calcium carbonate content aided degradation while organic matter increased persistence.
Measurement of clozapine and norclozapine in plasma/serum by high performance liquid chromatography with ultraviolet detection
Authors: McCarthy P. T. , Hughes S. , Paton C. 
Published: May 2005

AbstractA simple method for the measurement of clozapine and its N‐desmethyl metabolite in human pläsma or serum by high performance liquid chromatography is described. An internal standard (aqueous nortriptyline, 4 mg/L) (50 μL) and Tris buffer (2 mol/L, pH 10.6) (100 μL) are added to plasma/serum (200 μL) and the analytes and internal standard extracted into methyl tert‐butyl ether (200 μL). The extracts are analysed on a 150 mm column containing Spherisorb S5SCX using methanol containing ammonium perchlorate (35 mmol/L, pH 6.7) as eluent at a flow rate of 1.5 mL/min. Detection is by ultraviolet absorption (215 nm). The limit of detection is better than 0.05 mg/L for both analytes and the intra‐assay precision (CV) for clozapine and norclozapine was 5.3 and 7.3% at 0.5 mg/L and 2.6 and 2.8% at 1.5 mg/L, respectively. The method can be applied to the measurement of these compounds in plasma after acute overdosage, for the assessment of compliance in patients apparently refractory to therapy and to identify interactions between clozapine and other neuroleptic and antidepressant drugs which may effect toxicity.
Investigation of enantioselective ofloxacin—albumin binding and displacement interactions using capillary affinity zone electrophoresis
Authors: Arai Takashi , Nimura Noriyuki , Kinoshita Toshio 
Published: May 2005

AbstractThe direct chiral separation of ofloxacin by capillary affinity zone electrophoresis using serum albumins from different animal sources as chiral selector in the supporting electrolyte is described. In addition, the effects of displacers on the mobility and enantioselectivity of ofloxacin were studied. Firstly, the separation behaviour of the enantiomers of the ofloxacin (OFLX) and tryptophan (Trp) was compared. The influence of albumin types, including chemically modified bovine serum albumins (BSAs), and buffer types on the migration behaviour of enantiomers was investigated. The results showed that stereoselectivity of Trp is independent of the type of albumin used. However, chiral separation of OFLX depends on the biological species of albumin. Use of chemically modified BSA led to poorer resolution of enantiomers. Only with acetylated BSA could chiral separation of Trp be achieved. Using Good's buffer solutions (DIPSO and HEPES) as a supporting electrolyte affected the migration times of OFLX enantiomers. Finally, a variety of displacers were added to the buffer along with the protein, and the effects on separation behaviour were observed. The displacers included warfarin, ketoproten, diazepam, propranolol, benzoinphenylbutazone, digitoxin and octanoic acid. From the results obtained, it is concluded that capillary affinity zone electrophoresis using albumin as a chiral selector may allow screening of OFLX‐displacer interactions.
Dye—ligand affinity chromatography on continuous beds
Authors: Mohammad Jamil , Zeerak Asadullah , Hjertén Stellan 
Published: May 2005

AbstractContinuous beds derivatized with three triazine dyes (Cibacron Blue 3G‐A, Pricon Red HE‐3B and Pricon Red H‐3B) were used for chromatographic purification of dehydrogenases from yeast enzyme concentrate. All three columns, which were prepared by a very simple and cost‐effective method, provided strong binding of glucose‐6‐phosphate dehydrogenase and lactate dehydrogenase. The Cibacron Blue 3G‐A column showed high affinity for alcohol dehydrogenase. Under the same conditions, the Pricon Red HE‐3B column showed a lower affinity and the Pricon Red H‐3B column showed none. The adsorbed dehydrogenases were eluted specifically from the columns in high yields (71–113% by desorption with the coenzymes NADP, NADH and NAD respectively). Non‐specific binding of human serum albumin and transferrin to these columns was also investigated. Enzyme assays and analyses by capillary electrophoresis showed that the continuous beds derivatized with triazine dyes gave a high degree of purification.
Use of liquid chromatography for the determination of interactions between bioactive compounds
Authors: Cserháti Tibor , Forgács Esther 
Published: May 2005

AbstractMolecular interactions can be easily determined both by thin‐layer and high performance liquid chromatography. The theory and practice of the determination of molecular interactions and the various methods for the calculation of complex stability are presented. Examples of the applications of liquid chromatographic methods for the measurements of molecular interactions are also discussed.
Determination of free fatty acids in blood, tagged with 4‐(2‐carbazoylpyrrolidin‐1‐yl)‐7‐(N, N‐dimethylaminosulfonyl)‐2, 1, 3‐benzoxadiazole, by high‐performance liquid chromatography with fluorescence detection
Authors: Toyo'oka Toshimasa , Takahashi Maki , Suzuki Asako , Ishii Yasuko 
Published: May 2005

AbstractThe free fatty acids in blood were determined by high‐performance liquid chromatography (HPLC) after pre‐column tagging with 4‐(2‐carbazoylpyrrolidin‐1‐yl)‐7‐(N,N‐dimethylaminosulphonyl)‐2, 1, 3‐benzoxadiazole (DBD‐ProCZ). The tagging conditions were optimized with palmitic acid (C16:0) and linoleic acid (C18:2) as representative free fatty acids, saturated and unsaturated, respectively. Under the mild reaction conditions of room temperature for 90 min in dimethylformamide (DMF) containing 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide hydrochloride (EDC, 0.2 M)/pyridine (2%), all the fatty acids tested were tagged with the DBD‐ProCZ to produce highly fluorescent derivatives which emit light at 550 nm (excitation at 450 nm). The fluorescence wavelenghts were essentially the same for all fatty acids, whereas the intensities were different for individual fatty acids. The derivatives obtained from ten free fatty acids were completely separated by reversedphase chromatography with two isocratic elution conditions. The on‐column detection limit (signal‐to‐noise ratio of 3) with proposed HPLC separation and fluorescence detection is in the range of 19 (palmitic acid) −176 fmol (palmitoleic acid). The free fatty acids in rat serum and human plasma were successfully determined using the present method.
Identification of 9, 10‐epoxyoctadecanoic acid in human urine using gas chromatography‐mass spectrometry
Authors: Ulsaker Gunnar A. , Teien Gerd 
Published: May 2005

Abstract9, 10‐epoxyoctadecanoic acid has been detected in human urine. Two simple purification procedures were used; the one based upon liquid‐liquid extraction and the other based upon sorbent extraction technology isolating the free fatty acid fraction. Prior to trimethylsilylation and gas chromatographic‐mass spectrometric analysis, both the epoxy and carboxy functions were reduced to hydroxy groups. The shift in fragmentation of a deuterated sample verified the presence of intact epoxide prior to chemical reduction. Special attention was paid to the risk of false identification of the epoxide. The content of 9, 10‐epoxyoctadecanoic acid in human urine was estimated to be 2.1 nM/L.
Determination of D‐amino acids, derivatized with 4‐fluoro‐7‐nitro‐2, 1, 3‐benzoxadiazole (NBD‐F), in wine samples by high‐performance liquid chromatography
Authors: Kato Masaru , Fukushima Takeshi , Santa Tomofumi , Homma Hiroshi , Imai Kazuhiro 
Published: May 2005

AbstractThe concentrations of D‐amino acids and their enantiomeric ratios in wine samples were determined by high‐performance liquid chromatography with fluorometric detection. We used Pirkle type chiral stationary phases and fluorogenic reagent, 4‐fluoro‐7‐nitro‐2,1,3‐benzoxadiazole (NBD‐F) for simplicity and high sensitivity. The amino acids determined were D‐enantiomers of alanine (Ala), aspartic acid, glutamic acid, isoleucine (Ile) and leucine (Leu). D‐Asparagine, ‐glutamine and ‐lysine were not detected. D‐Leu was detected in red and rosé wine samples, and D‐Ile was determined only in rosé wine. In contrast, neither D‐Leu nor Ile were detected in white wine samples. The concentration of D‐Ala was the most prominent among these amino acids with the highest content of approximately 180 μM (D/D+L ratio; 25%) in rosé wine.
Chromatographic investigation of the glycosylation pattern of alpha‐1‐acid glycoprotein secreted by the HEPG2 cell line; a putative model for inflammation?
Authors: Elliott Heather G. , Elliott Moira A. , Watson John , Steele Les , Smith Kevin D. 
Published: May 2005

AbstractIn certain pathophysiological conditions, such as rheumatoid arthritis, there are alterations in the glycosylation pattern of the acute phase protein, alpha‐1‐acid glycoprotein (AGP). These changes are likely to be functionally significant, however, verification of the latter role requires a system which reflectsin vivo glycosylation changes in AGP and also produces sufficient quantities of the protein for further study. The human hepatoma cell line HepG2 is documented as displaying a shift in the glycosylation pattern of glycoproteins from normal state to acute phase after stimulation with inflammatory mediators. We have isolated AGP from the culture medium of HepG2 cells both before and after stimulation with a cytokine preparation and analysed the glycosylation pattern of each preparation, after enzymatic release, by high pH anion‐exchange chromatography. Before stimulation, the glycosylated population was similar to a profile which was of AGP isolated from normal plasma; however, cytokine stimulation resulted in a shift to a profile which was consistent with that of AGP from a rheumatoid arthritis sufferer. Thus a HepG2 cell culture system is capable of being a crude model of the changes in glycosylation of acute phase proteins although it has a tendency to produce oligosaccharide chains which are not fully sialylated.
Binding site for basic drugs on α1‐acid glycoprotein as revealed by chemometric analysis of biochromatographic data
Authors: Kaliszan Roman , Nasal Antoni , Turowski Maciej 
Published: May 2005

AbstractInteractions between α1‐acid glycoprotein (AGP) and 52 basic drugs were quantified by means of highperformance liquid chromatography (HPLC). The HPLC retention parameters were related quantitatively to the hydrophobicity and molecular modelling parameters, giving rise to the prediction of relative drug‐AGP binding from the chemical structure of a drug. A structural model of one binding site on AGP, common for various classes of drugs, was defined which accounted for the observed and reported differences in binding to AGP. A combination of biochromatography and chemometrics has been presented as a promising new approach in biochemical/pharmacological studies.
High‐performance liquid chromatography with fluorescence detection of ebiratide using 4‐(N, N‐dimethylamino‐sulphonyl)‐7‐fluoro‐2, 1, 3‐benzoxadiazole as a fluorogenic reagent
Authors: Hamachi Yozo , Tsujiyama Tsuyosi , Nakashima Kenichiro , Akiyama Shuzo 
Published: May 2005

AbstractA sensitive high‐performance liquid chromatography (HPLC) method with fluorescence detection has been developed and applied to the determination of ACTH4–9 analogue (ebiratide), 4‐(N,N‐Dimethylamino‐sulphonyl)‐7‐fluoro‐2,1,3‐benzoxadiazole (DBD‐F) was used as a fluorogenic labelling reagent.Ebiratide in 0.1 m borate buffer (pH 9.0) was reacted with DBD‐F in acetonitrile solution at 50°C for 30 min. After cooling, the mixture was seperated by a reversed‐phase HPLC. Then DBD‐ebiratide was monitored at 580 nm with the excitation at 440 nm. The calibration curve was liner up to 10 pmol on column (r=0.999) with the detection limit of 0.25 pmol (signal‐to‐noise=3).
Determination of nitroimidazole residues in poultry tissues, serum and eggs by high‐performance liquid chromatography
Authors: Semeniuk Stanislaw , Posyniak Andrzej , Niedzielska Jolanta , Żmudzki Jan 
Published: May 2005

AbstractA simple high‐performance liquid chromatographic (HPLC) method was developed for determination of dimetridazole and metronidazole residues in poultry muscle, liver, serum and eggs. The drug residues were extracted from tissues and egg samples with acetonitrile followed by solid‐phase extraction clean‐up and HPLC analysis with photodiode array detector. Serum samples were treated with trichloroacetic acid, centrifuged and analysed without further clean‐up. The detection limits were 2 ng/g and 5 ng/mL of analysed tissue (egg) and serum samples, respectively. Average recoveries for spike levels of 10 and 20 ng/g ranged from 82 to 94%, and coefficients of variation were below 10%.
Determination of unbound L‐tryptophan in human plasma using high‐performance liquid chromatography with fluorescence detection
Authors: Jagannathan Vanitha , March Clark , Venitz Jürgen 
Published: May 2005

AbstractAn assay for the measurement of unbound L‐tryptophan concentrations in plasma was developed using reverse‐phase HPLC with fluorescence detection. Unbound L‐tryptophan from plasma was obtained using the Amicon MPS‐1 ultrafiltration device. L‐tryptophan binding to the membrane in the ultrafiltration device was not significant. A linear relationship between the peak‐area ratios (peak‐area of L‐tryptophan to internal standard) and concentrations of L‐tryptophan was obtained in the range of 0.1 μg/mL to 2.5 μg/L. The intra‐assay precision was less than 10% for each control (0.18 μg/mL, 0.75 μg/mL and 2.0 μg/mL). The inter‐assay precision was less than 15% for each control; the accuracy for each control, expressed as percent difference from nominal (%DFN), was less than 12%. This method was used to determine unbound L‐tryptophan concentrations in plasma from nine male subjects who participated in a clinical study.
Two‐Dimensional correlation method applied to Yb3+ vibronic sideband spectroscopy: Discrimination of fluorescence spectral features arising from different yb3+ binding sites
Authors: Roselli Cécile , Burie Jean‐René , Mattioli Tony , Boussac Alain 
Published: May 2005

AbstractYtterbium (Yb3+) vibronic sideband (VSB) spectroscopy allows the identification of the lanthanide ligands both in model compounds and in Yb3+ ‐reconstituted metalloproteins. In some cases there exist multiple binding sites which complicate the Yb3+ fluorescence spectrum. The presence of different sites can be deduced from the variation of the intensity of the VBSs, when the wavelength of excitation is varied. A general two‐dimensional (2D) correlation method developed by Noda can be potentially used to discriminate the different Yb3+ binding sites. A very simple procedure has been further developed so that, by using a few different spectra, usable information can be extracted from the 2D spectrum; the spectra were obtained with different wavelengths of excitation. This method is applied successfully in the present work on Yb3+‐reconstituted transferrin, which contains two spectroscopically different Yb3+ sites, in order to determine any structural difference between the two sites. © 1995 John Wiley & Sons, Inc.