bluuebunny/crossref_metadata_2025_split huggingface dataset:
High performance liquid chromatographic assay of Amicar, ε‐aminocaproic acid, in plasma and urine after pre‐column derivatization with o‐phthalaldehyde for fluorescence detection
Authors: Lam Stanley 
Published: May 2005

AbstractA simple, reliable and highly sensitive procedure was devised for measuring the levels of Amicar in blood and urine. 100 μL of serum or urine sample was added to 10 μL of a 10% w/v zinc sulfate solution and 100 μL of methanol, as previously described (Lam et al., 1980) for the removal of proteins by precipitation. 50 μL of the supernatant was then mixed with 300 μL of 1 M borate buffer containing D‐valine as the internal standard before derivatization with o‐phthalaldehyde. The amino acids were then separated by a stereoselective reversed‐phase system using a mobile phase containing 10% of acetonitrile in 2.5 mM Cu(II) complexes of L‐proline. The chromatography is highly selective, resolving Amicar from L‐valine which in turn is resolved from its unnatural D‐antipode, the internal standard. The procedure including sample preparation and separation required a total of 15 min. As little as 50 ng/mL of Amicar in body fluids could be detected as the o‐phthalaldehyde derivative by fluorescence.
Estimation of human blood plasma 5‐hydroxyindoleacetic acid and homovanillic acid
Authors: Wright‐Honari S. , Marshall E. F. , Ashton C. H. , Hassanyeh F. 
Published: May 2005

AbstractA method for simultaneous quantification of plasma homovanillic acid and 5‐hydroxyindoleacetic acid has been developed, permitting more efficient neurochemical examinations of these often interrelated biogenic amine systems. Zinc sulphate and sodium hydroxide solutions were used for precipitating the protein in plasma prior to injection on the column. This technique allows for cleaner chromatography, greater sensitivity and high precision. The method uses high performance liquid chromatographic separations of these compounds on C18 reversed phase columns with electrochemical detection. The detailed results from controls and untreated parasuicide patients are given.
Solid phase extraction and high performance liquid chromatographic determination of doxophylline in plasma
Authors: Lagana A. , Bizzarri M. , Marino A. , Mancini M. 
Published: May 2005

AbstractA sensitive and selective high performance liquid chromatographic doxophylline assay with ultraviolet detection has been developed for plasma samples. The drug is isolated from biological samples with a reversed phase C18 disposable extraction column. Plasma standard curves are linear for concentrations of doxophylline from 0.03 to 10 mg/L. At the therapeutic range concentrations, the recoveries are better than 96.9%. The coefficients of variation for the procedure are 4.1% and 2.7% for the concentrations 0.03 mg/L and 10 mg/L, respectively. By this method, pharmacokinetic profiles are obtained for six adult volunteers.
The measurement of nucleoside deaminases by high performance liquid chromatography and their use in clinical chemistry
Authors: Sherwood R. A. 
Published: May 2005

AbstractThe measurement of the nucleoside deaminases—cytidine deaminase, guanosine deaminase and adenosine deaminase—by reversed phase high performance liquid chromatography is reviewed. The clinical value of assaying the enzyme activity is discussed for each of these enzymes. Both cytidine deaminase and adenosine deaminase measurements have proven clinical value, although the use of the assay of cytidine deaminase in the diagnosis of pre‐eclampsia is probably not helpful.
Quantitation of the enantiomers of rimantadine and its hydroxylated metabolites in human plasma by gas chromatography/mass spectrometry
Authors: Choma Nadia , Davis Preston P. , Edom Richard W. , Fukuda Elaine K. 
Published: May 2005

AbstractA gas chromatographic/mass spectrometric procedure has been developed for the quantiation in human plasma of the enatiomers of rimanatadine and its three hydroxylated metabolites. The assay utilized derivatization of all analytes with the optically active reagent S‐α‐methyl‐α‐methoxy(pentafluorpheyl)acetic acid, selective ion monitoring, methane negative ion chemical ionization mass spectrometry and stable isotope dilution techniques. This method has been used to meausure plasma concentrations of the enantiomers of rimantadine, m‐hydroxyrimantadine and p‐hydroxyrimantadine (equatorial and axial epimers) in the ranges 2.5‐250, 2.5‐50, 1.25–62.5 and 1.25–62.5 ng/mL, respectively, in six subjects given a single 200 mg dose of racemic rimantadine. Although there are no significant differences in the concentration‐time profiles of R‐ and S‐rimantadine, large stereospecific differences in the disposition of their metabolites are observed.
Determination of enalapril and its active metabolite enalaprilat in plasma and urine by gas chromatography/mass spectrometry
Authors: Shioya Hiroaki , Shimojo Masako , Kawahara Yukinori 
Published: May 2005

AbstractThe method for the simultaneous determination of angiotensin‐converting enzyme (ACE) inhibitor enalapril and its active metabolite enalaprilat in plasma and urine was developed by gas chromatography/mass spectrometry. Enalapril and enalaprilat in plasma and urine were extracted and cleaned up by using Sep‐Pak C18 and silica cartridges. Derivatization was carried out using diazomethane and trifluoroacetic anhydride. Detection by selected ion monitoring was selected to m/z 288 (enalaprilat) and 302 (enalapril). The detection limit of enalapril and enalaprilat was 200 pg/mL in plasma and 2 ng/mL in urine. This method was applied to the pharmacokinetic analysis of enalapril and enalaprilat in body fluids.
A universal peroxyoxalate‐chemiluminescence detection system for mobile phases of differing pH
Authors: Hayakawa Kazuichi , Minogawa Eriko , Yokoyama Tohru , Miyazaki Motoichi , Imai Kazuhiro 
Published: May 2005

AbstractA universal peroxyoxalate–chemiluminescence detection system for high performance liquid chromatography, available for a variety of mobile phases, has been developed. The system consisted of a dual‐head short‐stroke pump and a chemiluminescence detector. The standard conditions using bis(2,4,6‐trichlorophenyl) oxalate (TCPO) as aryl oxalate were as follows. The first postcolumn solution was the mixture of 0.5 M imidazole–nitric acid (pH 7.5) and acetonitrile (1:4, v/v). The second was acetonitrile containing TCPO–hydrogen peroxide. These two solutions were delivered by the two pump‐heads. After the pH of the column eluate was adjusted to the optimum range (6.5–7.5) by the first postcolumn solution, the solution was mixed with the second postcolumn solution. After flowing through a reaction coil, the chemiluminescence of the mixture was monitored. Using this system, a high sensitivity (fmol level) was obtained for perylene as an analyte with mobile phases having different pH values (2.0–8.0). Polycyclic aromatic hydrocarbons became detectable to a high sensitivity even after the column separation using an acidic mobile phase. The detection sensitivity of nitrated pyrenes after on‐line electrochemical reduction using an acidic mobile phase was also increased. This system might be available for other aryl oxalates by some modifications of the postcolumn solutions.
Sensitive fluorometric detection of prostaglandins by high performance liquid chromatography after precolumn labelling with 4‐(N,N‐dimethylaminosulphonyl)‐7‐(1‐piperazinyl)‐2,1,3‐benzoxadiazole (DBD‐PZ)
Authors: Toyo'oka Toshimasa , Ishibashi Mumio , Terao Tadao , Imai Kazuhiro 
Published: May 2005

AbstractA highly sensitive and simple method for the determination of prostaglandins (PGs) by HPLC with fluorescence detection is described. PGs are converted to the corresponding fluorescence derivatives by the reaction with 4‐(N,N‐dimethylaminosulphonyl)‐7‐(1‐piperazinyl)‐2,1,3‐benzoxadiazole (DBD‐PZ) in the presence of 2,2′‐dipyridyl disulphide and triphenyl phosphine in acetonitrile. The reaction is completed at room temperature after 30 min. The DBD derivatives of nine PGs are separated within a single 45 min chromatographic run on a reversed phase ODS column with a linear gradient elution using water and acetonitrile. The detection limits (signal‐to‐noise ratio of 3) calculated from the standard mixture of PGs (6‐keto‐F1α, F1α, F2α, E1, E2, D2, limaprost, A1 and B1) are in the range 1.7–5.0 fmol. The applicability of the proposed procedure is evaluated to the detection of PGs added to rat plasma.
A high performance liquid chromatographic method for the determination of albuterol enantiomers in human serum using solid phase extraction and chemical derivatization
Authors: He Langchong , Stewart James T. 
Published: May 2005

AbstractA high performance liquid chromatographic method was developed for the simultaneous assay of R(−)‐ and S(+)‐albuterol in human serum. The assay involves solid phase extraction as a sample clean‐up step and derivatization of racemic albuterol to its diastereomeric thioureas with 2,3,4,6‐tetra‐O‐acetyl‐α‐D‐glucopyranosyl isothiocyanate. Chromatographic separation was accomplished under isocratic conditions using an octadecylsilane column and a mobile phase consisting of 29:71 acetonitrile:distilled water containing 0.1% triethylamine, pH 4.0 (adjusted with concentrated phosphoric acid) at a flow rate of 0.8 mL/min. The diastereomers were detected using a fluorescence detector set at 223 nm excitation and no emission filter. Racemic bamethane was used as internal standard. Drug to internal standard peak‐height ratios were linear over a 2–20 ng/mL range for each enantiomer. The limit of detection of each analyte was 1.0 ng/mL (S/N = 3).
High performance liquid chromatographic determination of azelastine and desmethylazelastine in guinea pig plasma and lung tissue
Authors: Langevin C. N. , Pivonka J. , Wichmann J. K. , Kucharczyk N. , Sofia R. D. 
Published: May 2005

AbstractAnalytical methods have been developed for the simultaneous quantitation of azelastine (AZ) and desmethylazelastine (DAZ) in guinea pig plasma and lung tissue. The methods require a 1.00 mL plasma sample and a minimum 0.100 g lung sample. Both methods employ liquid/liquid organic extraction and back‐extraction into dilute acid. Quantitation is performed by high performance liquid chromatography on a 2X250 mm 5 μm HypersilTM CPS column using fluroescence detection. The linear quantitative ranges for AZ.HCI and DAZ.HBr in plasma are 0.156–160 ng/mL and 0.313–160 ng/mL, respectively. The linear quantitative ranges for AZ.HCI and DAZ.HBr in lung tissue are 0.039–20 μg/g for both.
Purification of hydrophilic and hydrophobic peptide fragments on a single reversed phase high performance liquid chromatographic column
Authors: McKern Neil M. , Edskes Herman K. , Shukla Dharma D. 
Published: May 2005

AbstractHydrophilic peptides generated from enzymic fragmentation of proteins are difficult to purify because they are either weakly bound or unretained by the reversed phase C18 columns favoured for liquid chromatographic separation of peptide mixtures. To overcome this difficulty, peptides that were not bound or only weakly bound by a C18 RP column were reacted with phenyl isothiocyanate (PITC), as used in the initial step in Edman sequencing. The hydrophobic phenylthiocarbamyl (PTC) peptide derivatives produced by the reaction were rechromatographed on the same column. Peptides generated by tryptic digestion of equine cytochrome C were used as a model system to test whether a complete set of peptide fragments could be purified by this method using just one column and solvent system. All the expected hydrophobic tryptic peptides bound to the RP column and were resolved by elution with acetonitrile, but no hydrophilic peptides were recovered as pure fractions. The column breakthrough fraction was reacted with PITC and rechromatographed on the same column, producing a profile consisting of 19 bound peaks. Further rechromatography of some of the fractions at different column temperatures enabled all six of the expected hydrophilic peptides to be purified and identified. The technique has also been applied to the sequence determination of coat protein from peanut stripe potyvirus protein, eight hydrophilic tryptic peptides being recovered and identified as PTC derivatives.
Measurement of terbutaline and salbutamol in plasma by high performance liquid chromatography with fluorescence detection
Authors: McCarthy P. T. , Atwal S. , Sykes A. P. , Ayres J. G. 
Published: May 2005

AbstractA method is described for the determination of terbutaline and salbutamol in plasma from patients given maximal therapy for brittle asthma. The analytes were isolated by solid phase extraction on alkali‐treated Bond‐Elut, unmodified, silica columns and measured by high performance liquid chromatography with fluorescence detection (excitation wavelength 200 nm). The limits of detection for a 1 mL sample containing salbutamol and terbutaline were 1 μg/L and 2.5 μg/L, respectively. The intra‐assay precision (CV) for samples containing 25 μg/L was 3.6 and 5.0% respectively. This method was applied to the measurement of terbutaline in samples from patients given continuous infusions of the drug to assess whether this treatment might result in toxicity.
Analysis of morphine and its 3‐ and 6‐glucuronides by high performance liquid chromatography with fluorimetric detection following solid phase extraction from neonatal plasma
Authors: Hartley R. , Green M. , Quinn M. , Levene M. I. 
Published: May 2005

AbstractA rapid, sensitive and simple to operate high performance liquid chromatographic method for the simultaneous determination of morphine, morphine‐3‐glucuronide and morphine‐6‐glucuronide in plasma is described. The drug and its metabolites were extracted from plasma using commercially available reversed phase octylsilane bonded silica columns (1 mL Bond Elut C8, 50 mg). Chromatographic separation of morphine and its metabolites was achieved using a mobile phase, consisting of 2 mM sodium dodecyl sulphate in 0.05% phosphoric acid:acetonitrile (71.5:28.5 by volume), at a flow‐rate of 1.2 mL/min, in conjunction with a Waters Nova‐Pak C18 column (300 × 3.9 mm). The analytical column was used in combination with a Guard‐Pak module containing a Nova‐Pak C18 Guard‐Pak insert. Using fluorescence detection (excitation 245 nm, emission 335 nm), plasma levels in the region of 5–10 μg/L for the drug and its metabolites can be detected with only 200 μL of plasma. The method has been applied to studies of the disposition of morphine and its metabolites in premature neonates requiring mechanical ventilation who were receiving the drug intravenously; preliminary findings in patients at steady state are presented.
Direct enantiomeric high performance liquid chromatographic separation of propafenone and its major metabolite in serum on a cellulose tris‐3,5‐dimethylphenyl carbamate chiral stationary phase
Authors: Aboul‐Enein Hassan Y. , Bakr Soliman A. 
Published: May 2005

AbstractA direct, isocratic and simple liquid chromatographic method is described for the enantiomeric separation of propafenone (PRO) and its major metabolite, 5‐hydroxypropafenone, using a cellulose tris‐3,5‐dimethylphenyl carbamate (Chiralcel ODS) column. The sterochemical separation factor (α) obtained was 1.14 and the maximum stereochemical resolution factor (R) was 0.80 when using a mobile phase consisting of hexane: 2‐propanol: diethylamine (90:10:0.4) at 23°C. The hydroxy metabolite could not be successfully separted into its corresponding enantiomers under these chromatographic conditions. The method has been used to determine and identify the enantiomers of PRO and its hydroxy metabolite in a serum sample.
Determination of 5,10,15,20‐ tetra‐ (m‐hydroxyphenyl)chlorin in human plasma by high performance liquid chromatography
Authors: Wang Qiang , Ris Hans‐Beat , Altermatt H. J. , Reynolds Brenda , Stewart J. C. M. , Bonnett Raymond , Lim Chang Kee 
Published: May 2005

AbstractA high performance liquid chromatographic method for the determination of the photodynamic chemotherapeutic agent 5,10,15,20‐tetra(m‐hydroxyphenyl)chlorin (m‐THPC) in human plasma following intravenous infusion is described. The procedure involves extraction of the drug in plasma with methanol/dimethyl sulphoxide (4:1 v/v) containing 5,10,15,20‐tetra(p‐hydroxyphenyl)clorin as the internal standard and separation on a C18 reversed phase column with acetonitrile:0.1% trifluoroacetic acid (77:23 v/v) as the mobile phase. The drug was detected specifically and sensitively at its absorption maximum of 423 nm with a detection limit of 15 ng/mL (signal‐to‐noise ratio of 5). The intra‐ and inter‐assay coefficients of variation (CV) on analysis of a plasma spiked with m‐THPC (1 μg/mL) were 2.3 and 3.4% (n=6), respectively.
Synthesis of novel fluorogenic edman reagents, 7‐N,N‐dimethylaminosulphonyl‐4‐(2,1,3‐benzoxadiazolyl)isothiocyanate (DBD‐NCS) and 7‐aminosulphonyl‐4‐(2,1,3‐benzoxadiazolyl)‐isothiocyanate (ABD‐NCS)
Authors: Imai Kazuhiro , Uzu Sonoko , Nakashima Kenichiro , Akiyama Shuzo 
Published: May 2005

AbstractNovel fluorogenic Edman reagents, 7‐N,N‐dimethylaminosulphonyl‐4‐(2,1,3‐benzoxadiazolyl)isothiocyanate (DBD‐NCS) and 7‐aminosulphonyl‐4‐(2,1,3‐benzoxadiazolyl)isothiocyanate (ABD‐NCS) having no fluorescence themselves were synthesized. The derivatives of amino acids with DBD‐NCS fluoresce at 505 nm with excitation at 385 nm. They were separated on a reversed‐phase HPLC column and detected at the sub‐picomol level. Ala‐Phe derivatized with DBD‐NCS was cleaved by acid to generate DBD‐thiocarbamyl‐Ala.
Determination of paracetamol (acetaminophen) in blood and plasma using high performance liquid chromatography with dual electrode coulometric quantification in the redox mode
Authors: Whelpton Robin , Fernandes Karin , Wilkinson Kathleen A. , Goldhill David R. 
Published: May 2005

AbstractA simple, but sensitive, micro‐assay for paracetamol in blood and plasma is described. Samples were prepared by precipitation with trichloroacetic assay solution and the drug quantified by reversed phase liquid chromatography with dual electrode electrochemical detection in the redox mode (oxidation at +0.25 V followed by reduction at −0.15 V). The limit of detection was 0.1 mg/L for a 10 μL sample of blood or plasma, the coefficient of variation at this concentration being 11.4%. The method was applied to a study of gastric emptying in patients before and after cardiac surgery.
The determination of a new inhalational anaesthetic, sevoflurane, using an internal standard, xenon, by gas chromatography/mass spectrometry/selected ion monitoring
Authors: Miyano Kazuko , Tanifuji Yasumasa , Obata Toru 
Published: May 2005

AbstractA novel determination method for a new inhalation anaesthetic, sevoflurane, in a closed circuit in the presence of carbon dioxide absorbents is investigated using gas chromatography/selected ion monitoring with xenon as an internal standard. The decrease rate of sevoflurane with soda lime was 0.22%±0.158/h (mean±SD), while that with baralyme was 0.57%±0.115/h (mean±SD).
Determination of rafoxanide and closantel in ovine plasma by high performance liquid chromatography
Authors: Benchaoui H. A. , McKellar Q. A. 
Published: May 2005

AbstractA high performance liquid chromatographic method has been developed for the determination of rafoxanide and closantel in ovine plasma. Acetonitrile and chloroform were used for the extraction. The mean recoveries were 78.69% and 80.59% for rafoxanide and closantel, respectively. This method was applied to the characterization of rafoxanide plasma kinetics following oral administration of therapeutic doses to sheep.
Analysis of free and bound O‐phosphoamino acids in urine by gas chromatography with flame photometric detection
Authors: Kataoka Hiroyuki , Nakai Kiyohiko , Katagiri Yoshimi , Makita Masami 
Published: May 2005

AbstractA selective and sensitive method has been developed for the analysis of free and bound forms of O‐phosphoamino acids, such as O‐phosphoserine, O‐phosphothreonine and O‐phosphotyrosine, in urine samples by gas chromatography (GC). For free O‐phosphoamino acid analysis, the urine sample was extracted with trichloroacetic acid and run through an ion exchange column. For total (free plus bound) O‐phosphoamino acid analysis, the urine sample was hydrolysed in acid and base in order to release the O‐phosphoamino acid from peptides or proteins. O‐Phosphoamino acids in these prepared samples were converted into their N‐isobutoxycarbonyl trimethyl ester derivatives and then measured by GC with flame photometric detection (FPD‐GC). The calibration curve was linear in the range of 10–500 ng for each O‐phosphoamino acid, and the detection limits were 30–80 pg as injection amounts. O‐Phosphoamino acids in the urine samples could be selectively determined by the FPD‐GC method without any influence from coexisting substances. The recoveries of O‐phosphoamino acids added to urines and urine hydrolysates were 90–98% and relative standard deviations were 1.5–8.0%. By using this method, we investigated an age dependence of O‐phosphoamino acid excretion in normal subjects.
Gas chromatographic determination of mexiletine in human plasma with flame ionization detection after reaction with carbon disulphide
Authors: Song‐gang Ji , Qing‐hong Kong , Xiu‐lu Li , Ping Li 
Published: May 2005

AbstractA gas chromatographic method for the determination of mexiletine in human plasma is described. Mexiletine was simultaneously extracted and derivatized with carbon disulphide for separation and quantitation on a glass column (1.5 m × 3 mm i.d.) packed with 1.5% OV‐1 coated on 80–100 mesh Shimalite W (201D). The method required only 0.5 mL of plasma and could detect as little as 10 ng of mexiletine. It has been applied to the study of the pharmacokinetics of mexiletine in healthy volunteers.
Simple analysis of amoxycillin in plasma by high performance liquid chromatography with internal standardization and ultraviolet detection
Authors: Charles Bruce , Chulavatnatol Suvatna 
Published: May 2005

AbstractA simple high performance liquid chromatographic method with ultraviolet detection at 229 nm is described for quantitation of amoxycillin in plasma. After deproteination of plasma samples with perchloric acid and adjustment of the pH to 4.9, the supernatant was injected onto a reversed phase C18 column, using acetonitrile: phosphate buffer (0.01 M, pH 7.4) (1:25 v/v) as the mobile phase. Amoxycillin and the internal standard, cefadroxil, were eluted at 23 min and 12 min, respectively, without interference from endogenous substances. Processed samples were stable for at least 24 h at room temperature which permitted automated batch processing overnight. Calibration plots of the amoxycillin to cefadroxil peak‐height ratio vs. amoxycillin concentration were linear (P < 0.0001; r⩾0.995) from 0.25 mg/L to at least 16.0 mg/L. Between‐day and within‐day imprecision (CV) ranged between 3.7% and 17.7%. Absolute recovery for amoxycillin and cefadroxil exceeded 82%. The application was demonstrated by the analysis of amoxycillin in human plasma after a single orall dose of amoxycillin (250 mg) suspension.
Separation of reduced and oxidized glutathione by micellar electrokinetic capillary chromatography
Authors: Castagnola Massimo , Di Pierro Donato , Scatena Roberto , Tavazzi Barbara , Nocca Giuseppina , Rossetti Diana Valeria , Giardina Bruno 
Published: May 2005

AbstractThe separation of reduced and oxidized glutathione at an absolute sensitivity of about 100 pg by micellar electrokinetic capillary chromatography without derivatization is described. The time required for the separation is less than 10 min (the time between two following injections is about 15 min). The separation is characterized by high efficiency and good reliability. A partition mechanism is responsible for the high resolution observed. The method was utilized for the analysis of commercial preparations of glutathione and a good agreement with the expected results was obtained; the oxidation of the commercial glutathione in solution was easily analysed.