Validation of a simple spectrophotometric method for the rapid determination of salicylates in plasma

Abstract

Introduction

The determination of salicylate concentrations constitutes a critical aspect of medical diagnostics, particularly in emergency settings. High-performance liquid chromatography (HPLC) and spectrophotometry are efficient methods commonly utilized for this purpose. In emergency laboratories with limited resources, the validation of a cost-effective and reliable spectrophotometric method for salicylates in plasma becomes imperative. The present study aims to validate such a method, ensuring its applicability in toxicological emergencies within resource-constrained laboratories.

Materials and methods

The proposed spectrophotometric analysis relies on detecting salicylic ions amidst the presence of ferric salts, resulting in the formation of a distinct purple chelate complex. To ascertain the method's credibility, the validation guidelines established by the European Medicines Agency (EMA) were employed as a benchmark. A comprehensive validation process was conducted over a three-day period, with three levels of validation standards being considered.

Results

Following the EMA protocol, the spectrophotometric method demonstrated commendable fidelity, accuracy, and linearity over a concentration range of 50 to 500 mg/L. The limit of detection and quantification was found to be 10 and 50 mg/L, respectively, and the correlation coefficient was determined to be R² = 0.998. However, it is essential to acknowledge that interference with phenothiazines occurred at concentrations ranging from 50 to 100 mg/L. Despite this, the method's average sensitivity remains viable for practical use in cases of poisoning. The accuracy per concentration level proved satisfactory, with relative biases remaining below 15%, and the confidence intervals of mean recovery closely approximating the desired target value of 100%.

Conclusion

In conclusion, the presented spectrophotometric method stands out as an economical, straightforward, and user-friendly approach, ideally suited for toxicological emergencies when resources are limited. The method delivers satisfying results, establishing its practical utility in critical medical scenarios. This validated method holds immense promise for emergency laboratories facing resource constraints.