Method development and validation of preservatives (phenylformic acid, 2,4-hexadienoic acid, methyl 4-hydroxybenzoate, and propyl 4-hydroxybenzoate) by HPLC

A high performance liquid chromatography ( HPLC) method for the assay of phenylformic acid, 2,4-hexadienoic acid, methyl 4-hydroxybenzoate, and propyl 4-hydroxybenzoate preservatives was developed and validated. The use of a reversed-phase C-8 column using an isocratic elution system enabled four compounds to be separated simultaneously in one analytical run. The method was validated to demonstrate its selectivity, linearity, precision, accuracy, specificity, and robustness. The calibration curves showed good linearity for all four analytes over the concentration range 0.026 to 4000 mu g/mL. The correlation coefficients were in all cases greater than 0.999. The mean percent relative standard deviation values for precision studies were less than 2% in each case. This method represents a useful protocol for routine testing of preservatives.