Search

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. [ABSTRACT FROM AUTHOR]

The electrochemical properties of atranol and chloroatranol have been evaluated in order to use dual detection to develop a simple reverse-phase high performance liquid chromatographic (HPLC) method for the determination of these allergens in cosmetic products. For this purpose, a diode-array detector (DAD) and an electrochemical detector (ECD) operated in amperometric mode and equipped with a wall-jet cell and a glassy carbon electrode as working electrode have been used. The chromatographic conditions have been optimized and the hydrodynamic curves for both compounds have been obtained. An optimal separation with adequate electrochemical responses have been obtained using a 50 : 50 methanol : 0.2 % phosphoric acid solution as mobile phase. The ECD detection has been performed by applying a potential of 1.15 V vs. Ag/AgCl. Limits of detection of 10 μ L−1 for atranol and 29 μ L−1 for chloroatranol have been achieved using the amperometric detection mode. The proposed methodology has been applied with successful results for the direct determination of both allergens, without pretreatment steps of samples, in different cosmetic products based on hydroalcoholic solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Good electrochemical responses due to biocide oxidation on gold electrode. • The first HPLC-ECD method with gold electrode for biocide determination. • Good analytical features to control the amount of antimicrobial agents in cosmetics. • Successful results in cosmetic analysis with the HPLC-ECD method. Antimicrobial agents are added to a wide variety of products such as cosmetics to reduce the risk of microbial contamination and ensure the suitability and safety of the product. However, recent studies have shown that these compounds can have negative effects on human health and the environment. Therefore, it is crucial to develop analytical methods to control the amount of these compounds in personal care products to guarantee human health and product quality. This paper presents an HPLC method with electrochemical detection using a gold electrode for the determination of the most used antimicrobial agents in cosmetic products: methylparaben (MP), 4-hydroxybenzoic acid (4-HBA), phenoxyethanol (PE) and methylisothiazolinone (MIT). For this purpose, the electrochemical response of these compounds was evaluated on the gold electrode. The optimal electrochemical detection of MP, 4-HBA; PE and MIT was performed at pH 2 and + 1.50 V (vs Ag/AgCl). Under the optimal separation and detection conditions, limits of detection (LODs) between 10 and 110 μg L−1 were obtained. These LODs are lower than those previously reported for other HPLC methods with mass spectrometry and diode-array detectors. Cosmetic products with different compositions were successfully analysed with the proposed HPLC method obtaining recoveries between 76 % and 119 %. [ABSTRACT FROM AUTHOR]

• HPLC-DAD-FLD method for reliable identification and determination of preservatives. • Simple and rapid procedure to extract preservatives from different cosmetics. • Preservatives are successfully determined in a single run with dual detection. • The method is useful to ensure compliance with regulations on cosmetics. A high-performance liquid chromatography (HPLC) method with two in-line detectors has been developed for detection and quantification of preservatives in personal care products. Five of the most common preservatives in cosmetics, methylisothiazolinone (MIT), chloromethylisothiazolinone (CMIT), 4-hydroxybenzoic acid (HBA), phenoxyethanol (PE) and methylparaben (MP) were selected as target compounds. UV–visible and fluorescence spectra of these compounds at different pH values were registered to optimize detection conditions using both, diode array (DAD) and fluorescence (FLD) detectors. The optimal separation was achieved using an acetonitrile - acetate buffer (0.05 mol L−1, pH 4) mobile phase with a gradient elution program. The limits of quantification are far below the established levels in the European Regulations for these compounds in cosmetic products. The method has been successfully applied to analyse different types of personal care products such as facial tonics, mouthwashes, shampoos, hair sprays, hair conditioners or body creams. A simple sample pre-treatment was performed before the chromatographic analysis. The dual diode-array and fluorescence detection allows the reliable identification and quantification of these preservatives using a unique sample extract even if they are at very different concentration levels. [ABSTRACT FROM AUTHOR]