Micellar electrokinetic chromatography of X-ray film developing baths

A simple and fast micellar electrokinetic chromatographic (MEKC) method for the determination of five main compounds (hydroquinone, metol, phenidone, 2-hydroxy-5-methylaminobenzenesulphonate and 2,5-dihydroxybenzenesulphonate) in X-ray film developing solutions was developed. The optimal conditions for the separation were established by varying the concentration of sodium dodecyl sulfate (SDS), the electrolyte pH and the temperature. Successful results were obtained with a 25 mmol L-1 Tris-phosphate buffer at pH 9.0 in the presence of 50 mmol L-1 SDS using direct UV detection at 214 nm. Under these conditions, baseline separation of the five compounds was achieved in less than 8 min. The method was validated in terms of precision, linearity, accuracy, and successfully applied to the analysis of X-ray film developing baths.