摘要:

A reagentless acetaldehyde sensor is designed based on the co-entrapment of aldehyde dehydrogenase (AIDH), NADH oxidase and high molecular weight NADs (NAD-dextran and NAD-PEG) in a polyvinyl alcohol) bearing stryrylpyridinium groups (PVA-SbQ) matrix. The amperometric detection is based on hydrogen peroxide oxidation by applying a potential difference of 550 mV between two platinum electrodes, equivalent toca.600 mVvs.SCE. The sensitivity is close to 2 mA 1 mol−1, the linear range extends from 0.5 μM to 330 μM acetaldehyde and the response time is lower than 3 minutes. More than 80 reproducible measurements can be performed without cofactor addition, indicating a good operational stability. Acetaldehyde concentration in alcoholic beverages is determined and validation of the results is made using a classical spectrophotometric method.

ISSN:0003-2719    

DOI:10.1080/00032719708004039

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A simple potentiometric method is described for mercurimetric titration of barbiturates using a solid-state iodide ion-selective electrode. The optimum titration conditions involve the use of a borate buffer of pH 9–10 as a medium and mercury(II) perchlorate of pH 1.7–1.9 as a titrant. Under these conditions, titration curves with two sharp consecutive inflection breaks are obtained. The first inflection corresponds to quantitative and stoichiometric reaction of barbiturates with mercury(II) and the second break is due to the reaction of the buffer with the titrant. No interferences are caused by Cl−, Br−, PO43-and many excipients and diluents commonly used in the drug formulations. Determination of barbiturates in various pharmaceutical preparations gives reproducible results with an average recovery of 99.1% of the nominal (st.dev. 0.3 %) and the method offers significant advantages over the titrimetric method of the British Pharmacopoeia.

ISSN:0003-2719    

DOI:10.1080/00032719708004040

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Captopril, 1-[(2S)-3-mercapto-2-methyl-1-oxopropyl]-L-Proline, can be deposited onto a silver electrode by a covalent bonding method to give a long-lived and stable chemically modified electrode(CME). Since the CME is prepared with a reaction between captopril and the substrate silver, the CME being prepared by this method is very stable. Furthermore, Hemoglobin(Hb) exhibits excellent voltammetric response at the modified electrode. Differential pulse voltammetric(DPV) measurements of the protein with this CME reveal the existence of a linear relationship between the anodic peak current and the concentration of Hb in the range of 2×10−6∼ 5×10−5mol/L. The detection limit is 8×10−7mol/L and the relative standard deviation of results is 5% for 6 successive determinations at 2×10-5mol/L. The determination of Hb for a real example is carried out.

ISSN:0003-2719    

DOI:10.1080/00032719708004041

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A stopped flow method for the determination of dopamine and methyldopa is proposed. The method is based on the aerial oxidation of these catecholamines in strong alkali medium. The method was optimized using a spectrophotometer (λ = 360 nm) as detector. Calibration graphs were linear up to 2 × 10−4mol/L for dopamine and 3.0 × 10−4mol/L for methyldopa with quantification limits of 3.5 × 10−6mol/L and 4.3 × 10−7mol/L for dopamine and methyldopa, respectively. The method was successfully applied to the determination of catecholamines in pharmaceutical formulations.

ISSN:0003-2719    

DOI:10.1080/00032719708004042

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

An endoglycosidase H (Endo H) assay based on the use of a glycoprotein enzyme as substrate, in conjunction with immobilised concanavalin A (Con A), was devised and investigated.

ISSN:0003-2719    

DOI:10.1080/00032719708004043

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A new simple, precise, rapid and selective RP-HPLC method has been developed for the simultaneous determination of Enalpril maleate and Hydrochlorothiazide from formulations, using 0.025M orthophosphoric acid [(adjusted to pH 3.0 with triethyl amine (TEA)]: Acetonitrile (84 16 V/V), as a mobile phase at a flow rate of 1.0 ml/min and μ Bondapak C18column (10 micron, 30cm × 3.9 mm) as a stationary phase. Detection was carried out using a UV detector at 226 nm. p-hydroxy phenyl acetamide (PHPA) was used as an internal standard. Linearity range and percentage recoveries for Enalpril maleate and Hydrochlorothiazide were 40–200 μg/ml and 50–500 μg/ml, 99.74 and 99.69 respectively. Minimum detection limit obtained was 0.8 μg/ml and 0.4 μg/ml for Enalpril maleate and Hydrochlorothiazide respectively.

ISSN:0003-2719    

DOI:10.1080/00032719708004044

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Two new spectrophotometric procedures for the determination of verapamil hydrochloride in pure as well as in pharmaceutical preparations were suggested. The methods are based on the formation of C.T. complexes with chromotrope 2B or chromotrope 2R azo dyes followed by extraction in chloroform and measuring the absorbances at 530 and 546 nm, respectively.

ISSN:0003-2719    

DOI:10.1080/00032719708004045

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Enantiomeric resolution of four racemic local anesthetics bupivacaine, mepivacaine, prilocaine and etidocaine were investigated on cellulose based chiral stationary phases. The phases studied were cellulose tris-3,5-dimethyl phenylcarbamate (Chiralcel OD) and cellulose trisbenzoate (Chiralcel OJ). Baseline separation (Rs>1.5) were achieved for bupivacaine and prilocaine enantiomers on Chiralcel OD using hexane-ethyl alcohol (99:1, v/v) and for etidocaine enantiomers on Chiralcel OJ using hexane-methanol (98:2, v/v). Etidocaine and mepivacaine enantiomers only gave partial separations (Rs≤0.81) on Chiralcel OD. The effects of various protic and aprotic organic modifiers were investigated on resolution and retention of the enantiomers.

ISSN:0003-2719    

DOI:10.1080/00032719708004046

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Two new spectrophotometric methods are used for the determination of acrivastine and pseudoephedrine hydochloride in their mixture without previous chemical separation. In the first, second derivative spectrophotometry, the measurements are made at 288.0 nm for acrivastine and at 270.2 nm for pseudoephedrine hydrochloride in the second derivative spectra of their solution in 0.1M NaOH. In the second, ratio spectra derivative spectrophotometry, the amplitudes are measured at 276.0 nm and 298.5 nm corresponding to two maximums for acrivastine, and at 252.6 nm and 268.3 nm corresponding to a maximum and a minumum, respectively, for pseudoephedrine hydrochloride in first derivative of their ratio spectra plotted by using of their solutions as divisor. The methods were successfully applied for the determination of these drugs in a commercial pharmaceutical formulation capsule.

ISSN:0003-2719    

DOI:10.1080/00032719708004047

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The 2.5th order differential polarographic reduction behavior of malonaldehyde (MLD) was studied. A sensitive measurement method of the determination of MLD for biological samples was given by using differential voltammetry with a static mercury drop electrode at a scanning speed of 80mV/s in a solution of 0.1mol/L NH4Cl. The linear response range of current(e″) against the concentration of MLD was 1.0×10−6to 1.0×10−3mol L and the detection limit was 1.0 × 10−7mol/L. The contents of MLD in the sample of cardiac myocytes was determined rapidly and simply by means of the method.

ISSN:0003-2719    

DOI:10.1080/00032719708004048

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor