M. Puttemans

Determination of Cinnarizine in Whole Blood and Plasma by Reversed Phase HFLC and its Application to a Pharmacokinetic Study

Abstract Cinnarizine is determined in whole blood and plasma by reversed phase HPLC on a RP-18 stationary phase. The one-step extraction is performed with a chloroform/hexane (2/3) mixture. A high recovery of 91% and a detection limit of 2 ng/ml are obtained as well as a good precision. The internal standard is meclozine. Pharmacokinetic parameters found are in accordance with data cited in literature.

Extraction of water-soluble acid dyes by ion-pair formation with tri-n-octylamine

Abstract Water-soluble acid dyes can be quantitatively extracted from aqueous solutions as ion pairs with tri-n-octylamine in chloroform or n-heptane. The parameters influencing the extraction are discussed. Back-extraction of the dye to an aqueous phase is possible with perchlorate ions.

Extraction of organic acids by ion-pair formation with tri-n-octylamine : Part 3. Influence of counter-ion and analyte concentration

The sorbate content of commercial yogurt samples is determined by reverse phase liquid chromatography following ion-pair extraction with tri-n-octylamine. Mean recoveries (70-88%), precision (1.1-3.3% RSD), and detection limit of the method are presented for sorbic acid, benzoic acid, and saccharin.Abstract Various acids of pharmaceutical interest are extracted into chloroform as ion-pairs with tri-n-octylamine. The influence of the counter-ion concentration on the extraction efficiency is investigated as a function of the concentration of the analyte. Side-reactions such as the formation of adducts take place and permit high recoveries to be obtained even for hydrophilic substances.

Extraction of organic acids by ion-pair formation with tri-n-octylamine : Part. 1. Extraction Rate and Influence of pH and Ionic Strength

Abstract The extraction scheme for dyes, developed previously, is applied to benzoic acid and its hydroxylated derivatives. Extractions are done with tri-n-octylamine at pH 5.5 and an ionic strength of 0.1 into chloroform. Equilibrium is attained in 20 min or less. The influences of pH and ionic strength of the extraction medium on the recoveries are described. The scheme developed for dyes is applicable for benzoic acid and salicyclic acid; for more polar acids the pH and ionic strength must be changed in order to maximize the recovery.

Separation and determination of the sodium, benzathine and procaine salts of benzylpenicillin by reversed phase high-performance liquid chromatography.

In the quality control of pharmaceuticals containing penicillin, there is a need for an analytical method which is faster and more specific than the microbiological [l] or the iodometric methods [2,3] in current use. When dealing with mixtures of penicillins prior separation is indispensable. High-performance liquid chromatography (HPLC) has been described by several authors for the determination of penicillins in pharmaceuticals [3-71 or in biological fluids [5, 81. Both ion-exchange chromatography [3] and reversed-phase HPLC [4-lo] have been proposed. The aim of the present work was to separate and quantitate mixtures of the sodium, procaine and benzathine salts of benzylpenicillin in one chromatographic procedure. Simultaneous resolution of these substances is difficult to achieve adequately in reversed-phase chromatography because of the presence of the acid benzylpenicillin, together with the two bases procaine and benzathine. Resolution can, however, be obtained by the careful choice of mobile phase pH and composition. Another method to influence the retention of ionizable compounds involves the addition of a counterion to the mobile phase. This increases the retention of ions of opposite charge and decreases the retention of ions with the same charge [ll]. Both these approaches are considered in the present work with regard to their application in the routine analysis of benzylpenicillin salts in pharmaceutical formulations.

Extraction of organic acids by ion-pair formation with tri-n-octylamine : Part 4. Influence of organic phase composition

Abstract Synthetic food dyes are extracted by ion-pair formation with tri-n-octylamine. Mixed organic phases are used, consisting of mixtures of hexane with one of the following solvent modifiers: chloroform, dichloromethane, methyl isobutyl ketone, butyl acetate or pentanol. Logarithmic plots of the distribution ratio versus the volume fracton of the solvent modifier are linear for dichloromethane, chloroform and pentanol. The efficiency of the solvents is classified as follows: dichloromethane > pentanol > chloroform > methyl isobutyl ketone > butyl acetate > hexane. The addition of pentanol to chloroform provides nearly quantitative recovery for hydrophilic solutes.

Extraction of organic acids by ion-pair extraction with tri-n-octylamine — VIII. Identification of synthetic dyes in pharmaceutical preparations

Synthetic dyes were extracted from syrups, oral suspensions, tablets, gelatin capsules, suppositories and granules by ion-pair formation with tri-n-octylamine (TnOA) and back-extracted with perchlorate ions. Identification was performed by TLC on cellulose layers and by reversed phase ion-pair HPLC.