Derivatization of ephedrine with o-phthaldialdehyde for liquid chromatography after treatment with sodium hypochlorite

The usefulness of the reaction with NaClO followed by derivatization with o -phthaldialdehyde (OPA) and N-acetyl-L-cysteine (NAC) has been investigated for the chromatographic analysis of ephedrine. The influence of parameters affecting the two-stage reaction has been evaluated, including concentrati on of NaClO, time of reaction, temperature and pH. On the basis of these st udies, conditions for the pre-column and (automated) post-column determinat ion of ephedrine are presented. The described conditions have been applied to the measurement of ephedrine in the concentration intervals 0.2-20.0 mu g/ml and 2.0-50.0 mu g/ml for the pre-column and post-column methods, respe ctively. The possibility of applying the NaClO/OPA-NAC method to other prim ary, secondary and tertiary derivative amphetamines has also been evaluated . (C) 2000 Elsevier Science B.V. All rights reserved.