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Determination of Diclofenac and Its Related Compounds using RP-HPLC-ICP-QQQ

Chlorine-based drugs, metabolites and related compounds were separated using reversed phase (RP) HPLC. Quantification was by compound-independent calibration, based on measuring the chlorine (Cl) heteroatom using triple quadrupole ICP-MS (ICP-QQQ).

Quantitative drug metabolite profiling is an important application in the pharmaceutical industry. Researchers involved in drug development require an analytical technique with a response that is independent of compound structure. This compound-independent response enables accurate quantification of the drug and its metabolites, without requiring compound-specific calibration. Currently, radiolabeling techniques followed by HPLC separation and radiodetection are used for this application, but a simpler, quicker, and safer alternative approach is desirable. The very high temperature plasma ion source and elemental ion-based measurement of ICP-MS enables compound structure-independent quantification, so individual standards for the metabolites of the (candidate) drug are not required. ICP-MS also links seamlessly with chromatography systems for speciation studies, for example HPLC.

This note describes the quantitative determination of the drug diclofenac and its related compounds in human plasma. Diclofenac is a prescription non-steroidal anti-inflammatory drug (NSAID) that is used to alleviate mild to moderate pain, fever, and inflammation. Compounds were quantified based on measurement of the Cl heteroatom using RP-HPLC-ICP-QQQ.