Analytical Sciences

Development and Validation of a Sensitive and Fast Solid-phase Spectrophotometric Procedure for Phenol Determination in Pharmaceuticals

Jadranka VUKOVIC,*1 Shiro MATSUOKA,*2 Kazuhisa YOSHIMURA,*3 Renata JURIŠIC GRUBEŠIC,*1 Dario KREMER,*4 and Nataša ŠANTIC*1

*1 Department of Analytics and Control of Medicines, Faculty of Pharmacy and Biochemistry, University of Zagreb, Ante Kovacica 1, HR-10000 Zagreb, Croatia
*2 Department of Environmental Science, Faculty of Science, Niigata University, Ikarashi, Niigata 950-2181, Japan
*3 Department of Chemistry, Faculty of Sciences, Kyushu University, Hakozaki, Higashi, Fukuoka 812-8581, Japan
*4 Department of Pharmaceutical Botany with Fran Kušan Botanical Garden, Faculty of Pharmacy and Biochemistry, University of Zagreb, Schrottova 37, HR-10000 Zagreb, Croatia

A very sensitive, simple, and fast solid-phase spectrophotometric procedure for the determination of phenol using the p-nitrobenzenediazonium reagent (DAR reagent) was developed. This procedure is based on the simultaneous concentration of the orange product on a Dowex 1-X2 anion exchanger within 15 min, and a direct absorbance measurement of the sorbed species at both 530 nm (the absorption maximum of the phenol-DAR in the resin phase) and 700 nm (the range where only the resin absorbs light). Quality control and evaluation of the analytical parameters was carried out using a comprehensive prevalidation strategy. The linearity of the method was confirmed within an analyte working range from 0.01 to 0.10 μmol (0.2 to 2.0 nmol mL⁻¹). The precision ranged from ±1.17 to ±9.61%; the accuracy ranged from −17.50 to +17.81%. The evaluated limiting values were L_D = 0.0013 μmol and L_Q = 0.0082 μmol. The DAR-SPS method was successfully applied to the determination of phenol in a pharmaceutical sample of salicylic acid (98.0 – 100.0%) and vaccines (98.0 – 103.4%).

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