Ultrasound Assisted Cloud Point Micro Extraction for the Determination of P-Hydroxybenzoic Acid and Some of its Alkyl Esters with HPLC

HPLC method after ultrasound assisted cloud point micro extraction (UA-CPME) for the simultaneous determination of p-hydroxy benzoic acid and its alkyl esters, methyl, ethyl, propyl and butyl paraben, which are widely used as preservatives in drug and cosmetic product was developed in this study. The chromatograms of these substances were recorded on a C18 column using gradient elution technique with various solvent systems at different flow rates and at 254 nm wavelength using DAD detector. The analysis conditions found by the classical method were optimized using the Box–Behnken design. The effect of each factor was examined with 3 factors for UA-CPME and 4 factors for HPLC analysis in this design. Brij 58 concentration (BC) Na 2 SO 4 amount (SA) and extraction time (ET) for UA-CPME, and mobile phase 1 (MP1), mobile phase 2 (MP2) ratio, flow rate (FR) and column temperature experiments for HPLC analysis were performed for the investigated levels. The factors affecting the resolution were determined by applying regression analysis to the experimental results. ANOVA test was applied to ensure result reliability. ANOVA test was used to determine the reliability of the results. A model was created with the obtained data. The developed method was validated by examining linearity, reproducibility, accuracy, limit of quantification and detection limit of the detection. Methyl paraben with 0.148% of RSD% value and 0.060% relative error%, and propyl paraben with 0.149% of % RSD value and 0.120% of relative error% in the syrup sample by the developed method. Methyl paraben with recovery values of (98,316-99,418) % and ethyl paraben with recovery values of (99,167-99,412) %, were determined in hand cream.