Simpler spectrophotometric assay of paracetamol in tablets and urine samples

A very fast, economical and simpler direct spectrophotometric method was investigated for paracetamol (PC) determination in aqueous medium without using any chemical reagents. The method is based on the photo-absorption of the analyte at 243 nm after dissolution in water. The change in structure of PC after addition of water was studied by comparing the corresponding FTIR spectra. Optimization studies were conducted by using a 5 μg ml−1 standard solution of the analyte. Various parameters studied include, time for stability and measurement of spectra, effect of HCl, NaOH, CH3COOH and NH3 for change in absorbance and shift in spectra, interference by some analgesic drugs and some polar solvents and temperature effect. After optimization, Beer's law was obeyed in the range of 0.3–20 μg ml−1 PC solution with a correlation coefficient of 0.9999 and detection limit of 0.1 μg ml−1. The newly developed method was successfully applied for PC determination in some locally available tablets and urine samples. The proposed method is very useful for quick analysis of various types of solid and liquid samples containing PC.