Indirect chemiluminescence-based detection of mefenamic acid in pharmaceutical formulations by flow injection analysis and effect of gold nanocatalysts

A highly sensitive flow injection-chemiluminescence detection (FI-CL) method based on periodate oxidation of two popular luminescent compounds for the determination of mefenamic acid (MFA) is presented. The method is an indirect CL detection method based on the CL emission generated during the oxidation of Pyrogallol (Pg) or Luminol (Lu) with the excess of periodate that remains after oxidation of MFA within the time period of 15 min. The MFA calibration curves obtained with either luminescent compounds were linear over a wide concentration range, depending on the system employed, offering detection limits in the range of low to ultra-low μg L−1 levels. Gold nanoparticles (Au-NPs) were also assessed as means for enhancing the CL signal. Pg-periodate was not affected by the presence of gold nanocatalysts as opposed to Lu-periodate CL signal which exhibited a significant increase in the presence of citrate synthesized Au-NPs. The reproducibility of the method, expressed by the relative standard deviation (R.S.D.), was very satisfactory and always below 5% as evidenced by repeated measurements (n ≥ 10) of standard solutions at two concentration levels (2 and 20 μg L−1).