# Simple spectrophotometric methods for the quantitative analysis of two binary mixtures containing paracetamol as a major component

## TL;DR

This paper introduces simple spectrophotometric methods to accurately measure paracetamol and other drugs in mixtures, using light absorption techniques.

## Contribution

The paper introduces new spectrophotometric methods for the simultaneous determination of paracetamol with meloxicam and domperidone in mixtures.

## Key findings

- Zero-order and first-order spectrophotometry methods were successfully used for mixture I.
- A ratio difference method was effective for mixture II.
- The methods showed high linearity and accuracy as per ICH criteria.

## Abstract

This work demonstrates simple and reliable spectrophotometric methods for the simultaneous determination of paracetamol (PAR) and meloxicam (MEL) in mixture I as well as PAR and domperidone (DOM) in mixture II in bulk form and laboratory-made tablets. Successful determination of mixture I was accomplished using direct zero-order spectrophotometry at 361 nm for MEL and first-order derivative (1D) spectrophotometry by measuring the peak at 342 nm and the trough at 262 nm for MEL and PAR respectively. On the other hand, a ratio difference method was suggested for the analysis of mixture II. The difference between the ratio spectra amplitudes at 256 and 288 nm were recorded for PAR determination, and 216 and 288 nm for DOM quantitation using 50 µg/mL DOM and PAR respectively as divisors. The efficacy of the proposed procedures was assessed using ICH criteria for linearity, ranges, precision, accuracy, detection, and quantitation limits. With regard to mixture I, the calibration curves showed linearity in the ranges of 3–30 µg/mL for MEL (zero-order method) and 2.5–30 and 3–15 µg/mL for MEL and PAR, respectively (first-order method), with correlation values of at least 0.9991.Whereas for mixture II, with correlation coefficients of 0.9999, the calibration curves for PAR and DOM were linear in the ranges of 3–70 and 2.5–15 µg/mL, respectively.The established procedures were used to analyze the combinations in the lab-prepared pills, and assay results were compared with reported methods. Greenness of the devised spectrophotometric procedures was assessed using the Analytical Eco-Scale and the Analytical Greenness metric (AGREE).

The online version contains supplementary material available at 10.1186/s13065-025-01643-7.