DETERMINATION OF THE PK(A) VALUES OF SPARINGLY SOLUBLE SUBSTANCES IN WATER REVISITED - APPLICATION TO SOME BENZODIAZEPINES

被引：8

作者：

DECASTRO, B ^{[1
]}

GAMEIRO, P ^{[1
]}

LIMA, JLFC ^{[1
]}

机构：

[1] FAC FARM PORTO, DEPT QUIM FIS, P-4000 OPORTO, PORTUGAL

来源：

ANALYTICA CHIMICA ACTA | 1993年 / 281卷 / 01期

关键词：

POTENTIOMETRY; TITRIMETRY; UV-VISIBLE SPECTROPHOTOMETRY; ACID-BASE EQUILIBRIA; ACIDITY CONSTANTS; BENZODIAZEPINES;

D O I：

10.1016/0003-2670(93)85339-L

中图分类号：

O65 [分析化学];

学科分类号：

070302 ; 081704 ;

摘要：

The acid-base behaviour of four benzodiazepines sparingly soluble in water (diazepam, medazepam, chlordiazepoxide and prazepam) was studied by potentiometric and spectrophotometric titrimetry in water. A method was devised to obtain the pK(a) values of these substances by potentiometric titrimetry in water-rich water-methanol media [up to 50% (v/v) methanol] by extrapolation to pure water, thus obviating the solubility problems associated with them. The method was found to be accurate and easily applicable, and the results obtained for the pK(a) values are identical, within experimental error, with those obtained in water. The operational criteria for applying this methodology are indicated.

引用

页码：53 / 62

页数：10

共 34 条

[1]

Albert A., 1971, DETERMINATION IONIZA

[2] AN EXAMINATION OF ACID-BASE EQUILIBRIA OF 1,4-BENZODIAZEPINES BY SPECTROPHOTOMETRY [J].

BARRETT, J ;

SMYTH, WF ;

DAVIDSON, IE .

JOURNAL OF PHARMACY AND PHARMACOLOGY, 1973, 25 (05) :387-393

[3]

BATES RG, 1973, DETERMINATION PH THE, P26

[4]

BATES RG, 1973, DETERMINATION PH THE, P372

[5] BIOPHARMACOLOGICAL DATA AND HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ANALYSIS OF 1,4-BENZODIAZEPINES IN BIOLOGICAL-FLUIDS - A REVIEW [J].

BERRUETA, LA ;

GALLO, B ;

VICENTE, F .

JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS, 1992, 10 (2-3) :109-136

[6]

FISCHER JB, 1986, RECEPTOR BIOCH METHO, V5, P241

[7] POTENTIOMETRIC TITRATIONS IN METHANOL WATER MEDIUM - INTERTITRATION VARIABILITY [J].

FISICARO, E ;

BRAIBANTI, A .

TALANTA, 1988, 35 (10) :769-774

[8]

FOYE WO, 1988, PRINCIPLES MED CHEM, P1

[9]

GALSTER H, 1991, PH MEASUREMENT FUNDA, P18

[10] SUPERQUAD - AN IMPROVED GENERAL PROGRAM FOR COMPUTATION OF FORMATION-CONSTANTS FROM POTENTIOMETRIC DATA [J].

GANS, P ;

SABATINI, A ;

VACCA, A .

JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS, 1985, (06) :1195-1200

← 1 2 3 4 →