A MWCNTs-COOH/PSS nanocomposite-modified screen-printed electrode for the determination of synthetic phenolic antioxidants by HPLC with amperometric detection

New sensing platforms based on screen-printed carbon electrodes modified with composites based on polystyrene sulfonate and oxidized multi-walled carbon nanotubes (PSS/MWCNTs-COOH/SPCE) have been used to develop a novel HPLC method with electrochemical detection (ECD) for the determination of the most used synthetic phenolic antioxidants in cosmetics: butylhydroxytoluene (BHT), butylhydroxyanisole (BHA), tert-butylhydroquinone (TBHQ) and propyl gallate (PG). Optimal separation conditions were achieved using methanol: 0.10 mol L-1 acetate solution at pH 6 as mobile phase with a gradient elution program from 60 to 90% of methanol percentage in 15 min. The electrochemical detection was carried out in amperometric mode using the PSS/MWCNTs-COOH/SPCE at + 0.80 V vs. Ag. Under these optimal separation and detection conditions, the limits of detection (LOD) were between 0.11 and 0.25 mg L-1. These LOD values were better, especially for BHT, than those previously published in other HPLC methods. Linear ranges from 0.37 mg L-1, 0.83 mg L-1, 0.69 mg L-1 and 0.56 mg L-1 to 10 mg L-1 were obtained for PG, TBHQ, BHA and BHT, respectively. RSD values equal or lower than 5% and 8% were achieved for repeatability and reproducibility, respectively. The HPLC-ECD method was successfully applied to analyze different cosmetic samples. Recovery values within 83-109% were obtained in the validation studies.

Automated summary

A new HPLC-ECD method employing a sensing platform based on screen-printed carbon electrodes modified with composites of polystyrene sulfonate and oxidized multi-walled carbon nanotubes has been developed for the determination of synthetic phenolic antioxidants in cosmetics. The method provides optimal separation conditions and achieves high sensitivity, accuracy, and repeatability, making it suitable for analysis of cosmetic samples.