Analysis of multi-class preservatives in leave-on and rinse-off cosmetics by matrix solid-phase dispersion

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.

Application of the poly (POSS-octavinyl-co-N-methylacetamide-co-divinylbenzene) solid extraction column in analyzing preservatives

In this study, a special poly solid-phase extraction (in-tube SPE) column consisting of poly (POSS-octavinyl-co-N-methylacetamide-co-divinylbenzene) [poly (POSS-OS-co-DVB-co-NMA)] was prepared based on the chemical structure of the preservatives, and was used as medium for extraction analysis in combination with UPLC. The composition of polymer SPE was optimized and characterized; good scanning electron microscopy (SEM) properties and satisfactory porosity were obtained with 30% monomer (POSS-OS:DVB:NMA = 2 wt%:13 wt%:15 wt%) and 70 wt% porogenic solvent (PEG20000:DMSO:ACN = 10 wt%:50 wt%:10 wt%). The experimental parameters of the in-tube SPE-UPLC analysis were optimized systematically. Then, the in-tube SPE-UPLC method was applied for analyzing the beverage sample, and correlation coefficients (R²) > 0.99 were obtained for the linear relationship within limits of 0.1~5.0 μg mL^-1. Excellent extraction efficiency, good precision, and satisfactory limit of detection sensitivity between 0.03 and 0.10 μg mL^-1 were obtained. The recovery ranged from 71.5 to 88.0%, with RSD ≤ 6.1%. Furthermore, the proposed method has the features of simple sample pretreatment, high throughput, rapid analysis, cost-effectiveness, and satisfactory sensitivity. Hence, the developed in-tube SPE-UPLC method based on the poly (POSS-OS-co-DVB-co-NMA) SPE column can be potentially used for simple and sensitive detection of preservatives.

Recent Advances in Sample Preparation for Cosmetics and Personal Care Products Analysis

The use of cosmetics and personal care products is increasing worldwide. Their high matrix complexity, together with the wide range of products currently marketed under different forms imply a challenge for their analysis, most of them requiring a sample pre-treatment step before analysis. Classical sample preparation methodologies involve large amounts of organic solvents as well as multiple steps resulting in large time consumption. Therefore, in recent years, the trends have been moved towards the development of simple, sustainable, and environmentally friendly methodologies in two ways: (i) the miniaturization of conventional procedures allowing a reduction in the consumption of solvents and reagents; and (ii) the development and application of sorbent- and liquid-based microextraction technologies to obtain a high analyte enrichment, avoiding or significantly reducing the use of organic solvents. This review provides an overview of analytical methodology during the last ten years, placing special emphasis on sample preparation to analyse cosmetics and personal care products. The use of liquid–liquid and solid–liquid extraction (LLE, SLE), ultrasound-assisted extraction (UAE), solid-phase extraction (SPE), pressurized liquid extraction (PLE), matrix solid-phase extraction (MSPD), and liquid- and sorbent-based microextraction techniques will be reviewed. The most recent advances and future trends including the development of new materials and green solvents will be also addressed.

Analytical methods for the determination of endocrine disrupting chemicals in cosmetics and personal care products: A review

Personal care products (PCPs) and cosmetics are indispensable product in our daily routine. Their widespread use makes them a potential route of exposure for certain contaminants to which human would not be normally exposed. One of these contaminants includes endocrine disrupting chemicals, molecules capable of mimicking the body's natural hormones and interfering with the endocrine system. Some of them are ingredients included in the product's formulation, such as UV-filters (sunscreens), phthalates (plasticizers and preservatives), synthetic musks (fragrances), parabens and other antimicrobial agents (antimicrobial preservatives). Others are non-intended added substances that may result from the manufacturing process or migration from the plastic packaging, as with bisphenols and perfluorinated compounds. Some of these endocrine disruptors have been restricted or even banned in cosmetics and PCPs given the high risk they pose to health. Thus, the development of fast, sensitive and precise methods for the identification and quantification of these compounds in cosmetics is a substantial need in order to ensure consumer safety and provide insight into the real risk of human exposure. The present work aims at reviewing the more recently developed analytical methods published in the literature for the determination of endocrine disrupting chemicals in cosmetics and PCPs using chromatographic techniques, with a focus on sample treatment and the quality of analytical parameters.

Multi-Target Strategy to Uncover Unexpected Compounds in Rinse-Off and Leave-On Cosmetics

The wide range and complexity of cosmetic formulations currently available on the market poses a challenge from an analytical point of view. In addition, during cosmetics manufacture, impurities coming from raw materials or formed by reaction of different organic compounds present in the formulation may be present. Their identification is mandatory to assure product quality and consumer health. In this work, micro-matrix solid-phase dispersion (μMSPD) is proposed as a multi-target sample preparation strategy to analyze a wide number of unexpected families of compounds including polycyclic aromatic hydrocarbons (PAHs), pesticides, plasticizers, nitrosamines, alkylphenols (APs), and alkylphenol ethoxylates (APEOs). Analytical determination was performed by gas chromatography-mass spectrometry (GC-MS) for the determination of 51 target compounds in a single run, whereas liquid chromatography tandem mass spectrometry (LC-MS/MS) was employed for the analysis of six APs and APEOs. Both methodologies were successfully validated in terms of linearity, accuracy, and precision in leave-on and rinse-off cosmetics. Limits of detection (LODs) were calculated in the low ng g⁻¹, showing their suitability to determine trace levels of impurities and banned compounds with different chemical natures, providing useful tools to cosmetic control laboratories and companies.

Parabens in stretch mark creams: A source of exposure in pregnant and lactating women

Parabens are widely used as antimicrobial preservatives in personal care products (PCPs). Stretch mark cream is widely used by pregnant and lactating women for the treatment of striae gravidarum. This can be a potential source of paraben exposure, not only to pregnant/lactating women but also to fetuses/newborns. Little is known, however, with regard to the occurrence of parabens in stretch mark creams. In this study, we analyzed eight parabens and their metabolites in 31 popular stretch mark creams originated from various countries including China. The concentrations of Σparaben (sum of eight parabens/metabolites) ranged from 0.007 to 1630 μg/g, with mean and median values of 453 and 273 μg/g, respectively. Methyl- and propyl-parabens accounted for >95% of Σparaben concentrations. We examined the measured paraben concentrations against ingredients listed on the product labels. Parabens were listed as ingredients in those creams that contained concentrations >100 μg/g except for four samples with such high concentrations. Six cream samples that were labeled 'paraben-free' contained trace levels (0.007-9.92 μg/g) of these preservatives. Mean dermal ∑paraben exposure dose from the use of stretch mark creams (30.6 μg/kg bw/day) was well below the current acceptable daily intake value (5 mg/kg bw/day). In comparison to diet and indoor dust ingestion pathways, paraben-laden stretch mark cream may be a major source of paraben exposure in pregnant and lactating women. This study provides information on parabens and other preservatives in stretch mark creams and measures to reduce exposures during pregnancy and lactation.

Simultaneous determination of 11 preservatives in cosmetics and pharmaceuticals by matrix solid-phase dispersion coupled with gas chromatography

A convenient method was developed for simultaneous determination of 11 preservatives in cosmetics and pharmaceuticals. Matrix solid-phase dispersion had been optimized as the sample pretreatment technology, using Florisil as a dispersant, anhydrous sodium sulfate as a dehydrant, formic acid as an additive, and n-hexane and ethyl acetate as eluents successively, and followed by gas chromatography–flame ionization detection on a TR-5 capillary column. Experimental results showed that 11 preservatives were baseline separated within 22 min. Good linearities were observed in the concentration range of 0.53–250 μg/mL for all analytes, and there were also minor differences. All correlation coefficients (r) were more than 0.995. The average recoveries at 3 levels of spiked samples ranged from 80% to 124% with 0.9–12% intra-day RSD and 1.8–12% inter-day RSD. The limits of detection were less than 0.18 μg/mL for all analytes. Besides, there was no obvious matrix effect on the analytes. The conclusion was that the developed method was simple, cheap, accurate, precise, and environment-friendly, in addition to existing little matrix effects. It could be recommended to determine 11 preservatives individually or in any their combinations to not only in liquid and gel cosmetics but also in liquid medicine and ointment.

A Green and Rapid Analytical Method for the Determination of Hydroxyethoxyphenyl Butanone in Cosmetic Products by Liquid Chromatography

An analytical method for the determination of hydroxyethoxyphenyl butanone, which is used as an alternative preservative in cosmetic products, has been developed and validated for the first time. The method is based on a simple ultrasound-assisted lixiviation of the analyte from the cosmetic matrix followed by liquid chromatography with UV spectrophotometric detection. Under optimized conditions, the method limit of detection and limit of quantification values were 30 and 90 µg·g−1, respectively. The method was validated with good recovery values (86–103%) and precision values (RSD 0.2–4.7%). Finally, the proposed analytical method was successfully applied to 7 commercially available cosmetic samples including both lipophilic and hydrophilic matrices, such as moisturizing cream, sunscreen, shampoo, liquid hand soap, and make-up. Additionally, a laboratory-made cosmetic cream containing the target analyte was prepared and analyzed. The good analytical figures of merit of the proposed method, in addition to its environmentally-friendly characteristics, demonstrate its usefulness to perform the quality control of cosmetic products to ensure the safety of consumers.

Miniaturized matrix solid-phase dispersion followed by liquid chromatography-tandem mass spectrometry for the quantification of synthetic dyes in cosmetics and foodstuffs used or consumed by children

Miniaturized matrix solid-phase dispersion (MSPD) followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) has been proposed for the simultaneous analysis of different classes of synthetic dyes in confectionery and cosmetics intended for or mostly consumed by children. Selected compounds include most of the permitted dyes as food additives as well as some of the most frequently used to color cosmetic products in accordance with the respective European directives. MSPD procedure was optimized by means of experimental design, allowing an effective, rapid and simple extraction of dyes with low sample and reagents consumption (0.1g of sample and 2mL of elution solvent). LC-MS/MS was optimized for good resolution, selectivity and sensitivity using a low ionic strength mobile phase (3mM NH₄Ac-methanol). Method performance was demonstrated in real samples showing good linearity (R≥0.9928) and intra- and inter-day precision (%RSD≤15%). Method LODs were ≤0.952μgg^-1 and ≤0.476μgg^-1 for confectionery and cosmetic samples, respectively. Recoveries of compounds from nine different matrices were quantitative. The validated method was successfully applied to 24 commercial samples (14 cosmetics and 10 foods) in which 9 of the selected dyes were found at concentrations up to 989μgg^-1, exceeding in some cases the regulated maximum permitted limits. A non-permitted dye, Acid Orange 7, was found in one candy.

Current trends in sample preparation for cosmetic analysis

The widespread applications of cosmetics in modern life make their analysis particularly important from a safety point of view. There is a wide variety of restricted ingredients and prohibited substances that primarily influence the safety of cosmetics. Sample preparation for cosmetic analysis is a crucial step as the complex matrices may seriously interfere with the determination of target analytes. In this review, some new developments (2010-2016) in sample preparation techniques for cosmetic analysis, including liquid-phase microextraction, solid-phase microextraction, matrix solid-phase dispersion, pressurized liquid extraction, cloud point extraction, ultrasound-assisted extraction, and microwave digestion, are presented. Furthermore, the research and progress in sample preparation techniques and their applications in the separation and purification of allowed ingredients and prohibited substances are reviewed.

Positive lists of cosmetic ingredients: Analytical methodology for regulatory and safety controls - A review

Cosmetic products placed on the market and their ingredients, must be safe under reasonable conditions of use, in accordance to the current legislation. Therefore, regulated and allowed chemical substances must meet the regulatory criteria to be used as ingredients in cosmetics and personal care products, and adequate analytical methodology is needed to evaluate the degree of compliance. This article reviews the most recent methods (2005-2015) used for the extraction and the analytical determination of the ingredients included in the positive lists of the European Regulation of Cosmetic Products (EC 1223/2009): comprising colorants, preservatives and UV filters. It summarizes the analytical properties of the most relevant analytical methods along with the possibilities of fulfilment of the current regulatory issues. The cosmetic legislation is frequently being updated; consequently, the analytical methodology must be constantly revised and improved to meet safety requirements. The article highlights the most important advances in analytical methodology for cosmetics control, both in relation to the sample pretreatment and extraction and the different instrumental approaches developed to solve this challenge. Cosmetics are complex samples, and most of them require a sample pretreatment before analysis. In the last times, the research conducted covering this aspect, tended to the use of green extraction and microextraction techniques. Analytical methods were generally based on liquid chromatography with UV detection, and gas and liquid chromatographic techniques hyphenated with single or tandem mass spectrometry; but some interesting proposals based on electrophoresis have also been reported, together with some electroanalytical approaches. Regarding the number of ingredients considered for analytical control, single analyte methods have been proposed, although the most useful ones in the real life cosmetic analysis are the multianalyte approaches.

Rapid determination of parabens in personal care products by stable isotope GC-MS/MS with dynamic selected reaction monitoring

In this study, a rapid and sensitive analytical method for the determination of methyl-, ethyl-, propyl-, and butyl esters of para-hydroxy benzoic acid (parabens) in personal care products was developed and fully validated. Test portions were extracted with methanol followed by vortexing, sonication, centrifugation, and filtration without derivatization. The four parabens were quantified by GC-MS/MS in the electron ionization mode. Four corresponding isotopically labeled parabens were selected as internal standards, which were added at the beginning of the sample preparation and used to correct for recovery and matrix effects. Sensitivity, extraction efficiency, and recovery of the respective analytes were evaluated. The coefficients of determination (r(2)) were all greater than 0.995 for the four parabens investigated. The recoveries ranged from 97 to 107% at three spiked levels and a one-time (single) extraction efficiency greater than 97% was obtained. This method has been applied to screen 26 personal care products. This is the first time that a unique GC-MS/MS method with dynamic selected reaction monitoring and confirmation of analytes has been used to determine these parabens in cosmetic personal care products.