Dispersive Liquid–Liquid Microextraction for the Determination of Salivary Melatonin as a Biomarker of Circadian Rhythm

Abstract

Melatonin (N-acetyl-methoxytryptamine) is secreted from a part of the brain called suprachiasmatic nuclei. The biological clock of the body or the circadian rhythm is regulated through the secretion of hormones such as melatonin and cortisol. The dispersive liquid–liquid microextraction (DLLME) was optimized for the determination of human salivary melatonin. Different variables including the nature of extracting and dispersing solvent, their volumes, sample pH, ionic strength, extraction and centrifugation times were screened using One Factor At a Time design and then, the significant variables were selected as optimum values. Accuracy and precision of the optimized method were evaluated at concentrations of 50, 100, 250 pg/mL by achieving CV% for day-to-day and within-day reproducibility. Considering the appropriate results of the study, DLLME procedure can be used for the determination of melatonin hormone in saliva samples.