摘要:

Spectrophotometric, colorimetric and densitometric methods for the determination of hydrochlorothiazide, benzydamine hydrochloride and clonazepam in the presence of their degradation products are described. Hydrochlorothiazide was determined in the presence of its degradation products methoxyhydrothiazide, hydroxyhydrothiazide and 5-chloro-2,4-disulfonamidoaniline applying the first and second derivative spectrophotometer at 278.8 nm and 254.4 nm, respectively, while benzydamine hydrochloride was determined in the presence of its toxic photodegradation products 5-hydroxybenzydamine and 2-B-dimethylaminopropyl-l-benzylindalolin-3-one colorimetrically using the acid dye bromophenol red and measuring the absorbance of the chloroform solution of the ion-pair formed at 425nm. Clonazepam was determined densitometrically in the presence of its degradation products carbostyril and 2-amino-2-chloro-5-nitrobenzophenone. The suggested methods determine hydrochlorothiazide, benzydamine hydrochloride and clonazepam in the presence of degradation products with mean accuracies of 99.57±0.51%, 100.04±0.41%, 100.03±0.21% and 99.84±0.34%, respectively. The proposed methods are suitable for stability testing in bulk powder and in pharmaceutical preparations.

ISSN:0003-2719    

DOI:10.1080/00032719708007224

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Due to the difference in reactivity of enantiomers with chiral reagents, it was found that in the Fast Atom Bombardment (FAB) mass spectra of enantiomer mixtures of R-α-phenylethylamine and S-α-phenylethylamine with a chiral reagent S-phosphorsaeure-(1,1′-bi-naphthyl-2,2′-diylester) (BNP acid), the relative abundance of the characteristic ion is linearly related to the composition of the mixture. We have, therefore, proposed a possible method for the determination of the optical purity of enantiomers by mass spectrometry.

ISSN:0003-2719    

DOI:10.1080/00032719708007225

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A method is described for the determination of ferrocene and its derivatives by the fluorescence quenching of europium-2-benzoyl-indan-1,3-dione-cetyltrimethyl-ammonium bromide(CTMAB) system. Under the optimum conditions, the decrease of the fluorescence intensity was a linear function of the concentration of ferrocene or its derivatives in the range 1.0 × 10−6-1.0 × 10−5mol/L. The detection limit was 1.0 × 10−7mol/L. The system was used for the determination of ferrocene n-heptyl β-diketone, with satisfactory results.

ISSN:0003-2719    

DOI:10.1080/00032719708007226

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The coloration reagent - leucomethylene blue, the reduction product of methylene blue, is used to determine the concentration of chlorine dioxide in the presence of Cl2and anion species such as OCl−, ClO2−and ClO3−. This simple spectrophotometric method is performed by using the extractant 1,2-dichloroethane at pH 1.3. The linear range of ClO2measurement extends to 0.95 mgl−1with a detection limit of 0.02 mgl−1. The presence of chlorine and hypochlorite ion can be masked by oxalic acid. The permissible maximum concentration of ClO2−is 2.0 mgl−1, and ClO3−anion does not interfere with the measurement.

ISSN:0003-2719    

DOI:10.1080/00032719708007227

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Several sulfite solutions at the level of 0.050 mol.L−1were kept at 25°C, in polyethylene flasks, in the presence and absence of air. The concentration of sulfite was periodically checked by the iodometric method. The presence of ethanolamine, ethylenediamine or tris(hydroximethyl)aminomethane, at 0.05 - 0.20 mol.L−1concentration levels, showed a remarkable stabilizing effect at pH values higher than 10.5. The amine ionization was supressed by the common ion effect by using OH−, added as NaOH. The changes in the concentration of S(IV) solutions in the presence of amine were about 1 to 3 %, during the period of 85 days. The stabilizing effect depends only on the amine group and not on the mixed function alcohol/amine. It was shown that an adduct of R-NH2.SO2type is not formed in aqueous medium. In the stock S(IV) solutions kept in highly alkaline medium a slow increase in pH was observed and disproportionation of sulfite ion was evidenced by formation of thiosulfate as revealed from ion chromatographic measurements. In the presence of oxygen dithionate ion is also formed.

ISSN:0003-2719    

DOI:10.1080/00032719708007228

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We report the use of solid phase microextraction (SPME) combined with ion mobility spectrometry (IMS) for sampling, screening and identification of organic compounds that are readily detected by IMS. This is a new SPME application. SPME has emerged recently as an excellent sample preparation technique for gas chromatography (GC) and high performance liquid chromatography (HPLC). We have found that SPME can be used very conveniently with IMS. An example of SPME-IMS is described using SPME headspace sampling at room temperature with 0.1 mL vials containing 1.0 microgram or less of either cocaine freebase or cocaine hydrochloride. This is followed by analysis using IMS. A hole, drilled in the IMS sample ticket holder, serves as the SPME-IMS interface.

ISSN:0003-2719    

DOI:10.1080/00032719708007229

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:0003-2719    

DOI:10.1080/00032719708007213

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor