Comparison of two methods for quinidine determination and chromatographic analysis of the difference
Härtel, G.; Harjanne, A.
Clinica Chimica Acta; International Journal of Clinical Chemistry 23(2): 289-294
ISSN/ISBN: 0009-8981 PMID: 5764906 DOI: 10.1016/0009-8981(69)90043-6
Two different methods for the determination of serum quinidine concentrations were compared. Extraction of quinidine with benzene and second transfer to sulfuric acid gave about 40% lower values than protein precipitation with alcohol-acetone and direct fluorimetric determination with and without the addition of acetic and sulfuric acid. This difference is due to a lower solubility of quinidine metabolites in the less polar solvent benzene, as shown by Chromatographie analysis of serum and urine extracts obtained by the two methods. Quinidine metabolites are considered of remarkably lower toxicity and antiarrhythmic activity than quinidine. Thus, because of its greater specifity for quinidine, the double extraction method of Cramér and Isaksson5 is regarded more suitable for the control of quinidine treatment than other methods.