摘要:

AbstractA rapid and highly sensitive determination method for urinary free cortisol has been developed using reversed phase high performance liquid chromatography (HPLC) with a precolumn for sulphuric acid‐ethanol fluorescence derivatization and column switching. Urinary cortisol, eluted from the octadecylsilane‐bonded silica (ODS) minicolumn with 90% aqueous ethanol, was derivatized with the addition of sulphuric acid only at ambient temperature. Cortisol derivatives injected directly onto the ODS precolumn were purified on‐line. After switching the columns, the cortisol derivative was separated on an ODS analytical column with a retention time of 15.3 min and monitored at an emission wavelength of 520 nm (exitation wavelength of 365 nm) to decrease the detection limit to 0.26 μg/dL (signal‐to‐noise ratio = 3). The automated HPLC operation resulted in good reproducibility and recovery of the stable cortisol derivat

ISSN:0269-3879    

DOI:10.1002/bmc.1130060302

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

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 bac

ISSN:0269-3879    

DOI:10.1002/bmc.1130060303

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractA highly sensitive and simple reversed phase high performance liquid chromatographic (HPLC) method for the quantitative determination of free fatty acids in human serum is presented. The method is based on the direct derivatization of serum fatty acids with 6,7‐dimethoxy‐1‐methyl‐2(1H)‐quinoxalinone‐3‐propionylcarboxylic acid hydrazide. The derivatization reaction proceeds in aqueous solution in the presence of pyridine and 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide at 37°C. The resulting derivatives are separated within 75 min on a reversed phase column (YMC Pack C8) with a gradient elution of aqueous acetonitrile and detected fluorimetrically. The detection limits are 2.5–5 fmol in a 10 μL injection volume. The sensitivity permits precise determination of free fatty acids in 5 μL serum. The method is simple and is without the conventional liquid–liquid extractio

ISSN:0269-3879    

DOI:10.1002/bmc.1130060304

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractA sensitive determination method for a non‐fluorescent anti‐arrhythmic drug, mexiletine, in rat plasma is presented utilizing a HPLC peroxyoxalate chemiluminescence (PO‐CL) detection system. After an internal standard (4‐methylmexiletine, 4.35 pmol) and 0.1 N sodium hydroxide solution were added to 5 μL rat plasma, the solution was poured onto an Extrelut 1 column. Both mexiletine and the internal standard were eluted with diethy ether and then the eluate was evaporated to dryness. The residue was dissolved in 0.2 M borate buffer (pH 8.5) and mixed with dansyl chloride (75 nmol) in acetronitrile. After standing of 90 min at room temperature, 0.5 N HCI was added to the reaction mixture to stop the reaction and a 2/45 aliquot of the mixture was subjected to a HPLC PO‐CL detection system using bis(4‐nitro‐2(3,6,9‐trioxadecyloxycarbonyl)phenyl)oxalate (TDPO) and hydrogen peroxide. The calibration curve for mexiletine in rat plasma was linear over the range 20–100 ng/mL plasma (20.6–103 fmol/injection). The detection limit (S/N= 2) was 1.0 fmol over the whole procedure. The method was applied to the measurement of the time courses of plasma mexiletine concentration after oral administration of the drug [25 mg (115

ISSN:0269-3879    

DOI:10.1002/bmc.1130060305

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractMethotrexate (MTX) has been convalently attached to an IgG‐type monoclonal antibody (791T/36) directed to tumour‐associated antigen gp72. Conjugates were synthesized by the active ester method using MTXN‐succinimidyl ester at various pH values (7.5–10.5). Following purification by gel filtration, high performance liquid chromatography was used to assess the free drug or its derivatives in samples of MTX–791T/36 conjugates previously treated (or not) with hydroxylamine. Quantitative analysis, performed on a reversed phase column (pore size 300 Å) with isocratic acetonitrile–sodium acetate buffer (pH 4.8) as mobile phase, indicated no detectable amount of free methotrexate in hydroxylamine‐treated conjugates even six months after their preparation. Similar observations were made with conjugates, whose synthesis were performed at pH ⩾ 10. In contrast, the presence of increasing amounts of drug/metabolite could be demonstrated in samples produced at lower pH values. Based on these findings, the pH‐dependent kinetics of MTX release has been determined and used to design conditions under which stable MTX–791T/36 conjugates could be prepared without hy

ISSN:0269-3879    

DOI:10.1002/bmc.1130060306

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractAfter inhalation experiments with sandalwood oil and the pure fragrance compounds coumarin and α‐terpineol, substances were detected and measured in the blood samples of test animals (mice) using gas chromatography/mass spectrometry (GC/MS) (MID) in connection with GC/FTIR (SWC), GC/AES (carbon and oxygen trace) and flame ionization detection/gas chromatography. Using tiglinic acid benzyl ester as the internal standard the following concentrations in serum could be found: α‐santalol 6.1 ng/mL, β‐santalol 5.3 ng/mL and α‐santalene 0.5 ng/mL. In separate inhalation experiments with coumarin and with α‐terpineol the corresponding concentrations were 7.7 ng/mL and 6.9 ng/mL

ISSN:0269-3879    

DOI:10.1002/bmc.1130060307

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractA highly sensitive method for the determination ofN‐acetylneuraminic acid in human serum and urine is investigated. This method employs high performance liquid chromatography with chemiluminescence detection.N‐Acetylneuraminic acid, released by hydrochloric acid hydrolysis of serum and urine, andN‐glycolylneuraminic acid (internal standard) are converted into chemiluminescent derivatives with 4,5‐diaminophthalhydrazide dihydrochloride, a chemiluminescence derivatization reagent for α‐keto acids. The derivatives are separated within 35 min on a reversed phase column, TSKgel ODS‐120T, with isocratic elution, followed by chemiluminescence detection; the chemiluminescence is produced by the reaction of the derivatives with hydrogen peroxide in the presence of potassium hexacyanoferrate(III) in alkaline solution. The detection limit forN‐acetylneuraminic acid is 9 fmol (signal‐to‐noise ratio = 3). This sensitivity permits precise determination ofN‐acetylneuraminic acid in 10 nL of serum or 50 nL of urine. The method is applied to the determination of theN‐acetylneuraminic acid in human sera from normal subjects and cancer patien

ISSN:0269-3879    

DOI:10.1002/bmc.1130060308

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe content and dissolution rate of theophylline, diprophylline and proxyphylline from a sustained release formulation were determined by UVin situdensitometry. After separation the chromatographic zones corresponding to the spots of theophylline, diprophylline and proxyphylline on the high performance thin layer chromatographic plates were scanned in reflectance/absorbance mode at 275 nm. Quantification was performed with a second degree polynomial function over the range 40–200 ng for theophylline and 60–300 ng for diprophylline and proxyphylline. Percentages of dissolved theophylline, diprophylline and proxyphylline were monitored over 1, 3 and 6 h. The method was found to be simple, accurate, reliable, time‐saving (up to 18 samples can be determined simultaneously) and low

ISSN:0269-3879    

DOI:10.1002/bmc.1130060309

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

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, A1and B1) are in the range 1.7–5.0 fmol. The applicability of the proposed procedure is evaluated to the dete

ISSN:0269-3879    

DOI:10.1002/bmc.1130060310

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractA high performance liquid chromatographic assay of methamphetamine (MP) and its related compounds, i.e. ephedrine (EP), norephedrine (NE),p‐hydroxymethamphetamine (p‐HMP),p‐hydroxyamphetamine (p‐HAP) and amphetamine (AP), with peroxyoxalate chemiluminescence detection has been developed. 4‐(N,N‐Dimethylaminosulphonyl)‐7‐fluoro‐2,1,3‐benzoxadiazole (DBD‐F) was used as a fluorescent labelling reagent. A mixture of hydrogen peroxide and bis[4‐nitro‐2(3,6,9‐trioxadecyloxycarbonyl)phenyl] oxalate in acetonitrile was used as a postcolumn chemiluminogenic reagent. DBD derivatives of MP and its related compounds were separated by a gradient elution with acetonitrile and 0.01 M imidazole buffer (pH 7.0) within 65 min. The detection limits (S/N= 3) for the proposed method for MP, AP, EP, NE,p‐HMP andp‐HAP were 27, 100, 40, 133, 25 and 133 fmol on column, respectively. The recoveries of these compounds with normal urine samples were 87.4–106.4%. The method was successfully applied to the assay of MP and its metabolites in urine samples from MP addicts. A good linear correlation for the resulted amounts of MP or AP between the proposed method and gas chromatography was obtained

ISSN:0269-3879    

DOI:10.1002/bmc.1130060311

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY