Determination of Six Analgesics by CE with an Improved Electromagnetic Induction Detector

A novel, rapid and validated capillary electrophoretic method with an improved electromagnetic induction detector has been developed for the determination of ibuprofen, acetaminophen, amantadine hydrochloride, aminopyrine, diclofenac sodium and codeine phosphate in three kinds of analgesic pharmaceutical preparations. Fabrication of the electromagnetic inductor was the same as previously described, but a brand new electric circuit was designed for the detector to lower the background noise and improve the detection sensitivity. Important factors which might influence the response of the detector, including the value of the adjustable inductor and resistor, excitation frequency and voltage, were examined. Electrophoretic parameters affecting separation efficiency, such as variety of buffer, buffer pH, buffer concentration and electroosmotic flow modifier, were also deliberately investigated. Under the optimal conditions, highly linear response was obtained for these six compounds over three orders of magnitude with detection limits ranging from 0.1 to 1.0 μg mL −1 (S/N = 3). The average recovery and RSD were within the range of 97.5–101.5 and 1.1–2.3%, respectively. This simple, convenient, effective and stable method held great promise in quality control of pharmaceutical preparations.