Quantitative estimation of urinary ortho-cresol by high pressure liquid chromatography for biomonitoring of toluene exposed population

Aim: Quantification of urinary ortho-cresol (OC) by high pressure liquid chromatography coupled with photodiode array detector. Materials and Methods: Includes acid hydrolysis of urine, liquid–liquid extraction, and chromatography quantification of extracted OC in urine. Results: Limit of detection, limit of quantification, and coefficient of linearity (R2) were 0.18 μg/ml, 0.62 μg/ml, and 0.9998, respectively. Recovery % of method ranged from 92%, 97%, and 100%. For intraday and interday precision coefficient of variation was 0.41%, 0.64%, and 0.89%, 0.86% for urine samples spiked with OC standards final concentration of 0.25 μg/ml and 0.7 μg/ml, respectively. Results (mean ± standard deviation) of exposed and unexposed real urine samples analyzed for OC with this method were 0.92 ± 0.76 and 0.40 ± 0.20 μg/ml, respectively. Statistical analysis of results showed significant (P ≤ 0.001) difference between urinary OC among exposed and unexposed subjects. Conclusion: The present work describes precise, easy, and less time consuming method for estimation of OC in urine of population exposed to toluene. It can be used as a promising tool for biomonitoring of population exposed to toluene.