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 mu mol (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 mu mol and L-Q = 0.0082 mu mol. 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%).