A Rapid HPLC Analysis for Dermal Penetration: The Case Study of 4- Chloro-3-Methylphenol (CMP) from Metal Working Fluid Trim VX

A rapid and simple HPLC method has been developed for the determination of 4-chloro-3-methylphenol (CMP) in the metal working fluid (MWF), Trim VX and in experiments designed to measure the dermal penetration of CMP from MWF. The method used 2-methyl-4,6-dinitrophenol as an internal standard (IS). Water was used as the extraction solvent. The retention times of CMP and internal standard (IS) were 5.56 and 6.67 min, respectively. The standard plots of CMP are linear over the range of 62.5 2,500 ng·mL -1 with correlation coefficients of 0.999. The limit of quantification (LOQ) for CMP was estimated to be 62.5 ng·mL -1 and the limit of detection (LOD) was approached to be 20 ng·mL -1 . Reproducibility of the sample handling and HPLC analysis had a relative standard deviation (RSD) of less than 6%. The average recoveries for the analyte in Trim VX were better than 92%. Using the method, we found that Trim VX contains 2% CMP. In our preliminary dermal penetration study, the permeability coefficient kp and lag time were estimated to be 4.88 10 -3 cm·h -1 and 1.65 h, respectively.