Volatile methylsiloxanes in personal care products - Using QuEChERS as a "green" analytical approach

Interference of the gas chromatography- mass spectrometry instrumental background on the determination of trace cyclic volatile methylsiloxanes and exclusion of it by delayed injection

Cyclic volatile methylsiloxanes (cVMS) have been widely found in various types of environmental media and attracted increasing attention as new pollutants. However, there is still a great challenge in the accurate quantification of trace cVMS, due to their volatility, and the high background originating from GC/MS accessories and surroundings. In this work, the main sources of the high background were investigated in detail for octamethylcyclotetrasiloxane (D4), decmethylcyclopentasiloxane (D5) and dodecmethylcyclohexosiloxane (D6). Several effective measures were employed to minimize these backgrounds, including the delayed injection method to minimize the interference from the injection septum. Then, a GC-MS method was developed for the accurate determination of D4, D5 and D6, with a linear range of 2 - 200 μg/L. The coefficient of determination was 0.9982-0.9986, the limit of detection (LOD) was 0.40-0.52 μg/L, and the quantitative range was 1.88-190 μg/L. Good reproducibility and recovery were obtained, indicating the reliability of the established analytical method.

Factors determining contamination and time trends in cyclic and linear siloxanes in sediments from an industrialized lake in Korea

Siloxanes, widely used in various consumer and industrial products, are emerging concerns of contaminants. Despite this, limited studies have been conducted on contamination and time trends on siloxanes in coastal environments. In the present study, four cyclic and 15 linear siloxanes were measured in sediments collected from an artificial saltwater lake in Korea during 2001-2016 to investigate contamination, time trends, and ecotoxicological concerns. Cyclic siloxanes were detected in all sediment samples, whereas linear siloxanes were not frequently detected. The highest siloxane concentrations were observed in creeks passing through various industrial complexes, indicating that industrial activities predominantly contributed to siloxane contamination in coastal environments. Decamethylcyclopentasiloxane (D5) and dodecylcyclohexasiloxane (D6) were predominant siloxanes in sediments over the last two decades. Siloxane concentrations significantly increased in creek sediments from 2008 to 2016, whereas those in inshore and offshore regions significantly decreased due to a strong dilution effect by the operation of tidal power plant. This suggests that consumption patterns and coastal development activities are crucial factors determining the contamination and time trends in the sedimentary siloxanes. The sedimentary concentrations of octamethylcyclotetrasiloxane (D4) and D5 exceeded several thresholds, raising the potentials for ecological risks to aquatic organisms.

Helping WWTP managers to address the volatile methylsiloxanes issue-Behaviour and complete mass balance in a conventional plant

Volatile methylsiloxanes (VMSs) are a group of additives employed in different consumer products that can affect the quality of the biogas produced in wastewater treatment plants (WWTPs). The main objective of this study is to understand the fate of different VMSs along the treatment process of a WWTP located in Aveiro (Portugal). Thus, wastewater, sludge, biogas, and air were sampled in different units for two weeks. Subsequently, these samples were extracted and analyzed by different environment-friendly protocols to obtain their VMS (L3-L5, D3-D6) concentrations and profiles. Finally, considering the different matrix flows at every sampling moment, the mass distribution of VMSs within the plant was estimated. The levels of ∑VMSs were similar to those showed in the literature (0.1-50 μg/L in entry wastewater and 1-100 μg/g dw in primary sludge). However, the entry wastewater profile showed higher variability in D3 concentrations (from non detected to 49 μg/L) than found in previous studies (0.10-1.00 μg/L), likely caused by isolated releases of this compound that could be related to industrial sources. Outdoor air samples showed a prevalence of D5, while indoor air locations were characterized by a predominance of D3 and D4. Differences in sources and the presence of an indoor air filtration system may explain this divergence. Biogas was characterized by ∑VMSs concentrations (8.00 ± 0.22 mg/m3) above the limits recommended by some engine manufacturers and mainly composed of D5 (89%). Overall, 81% of the total incoming mass of VMSs is reduced along the WWTP, being the primary decanter and the secondary treatment responsible for the highest decrease (30.6% and 29.4% of the initial mass, respectively). This reduction, however, is congener dependant. The present study demonstrates the importance of extending sampling periods and matrices (i.e., sludge and air) to improve sample representativity, time-sensitivity, and the accuracy of mass balance exercises.

Applications of mass spectrometry in cosmetic analysis: An overview

Mass spectrometry (MS) is a crucial tool in cosmetic analysis. It is widely used for ingredient screening, quality control, risk monitoring, authenticity verification, and efficacy evaluation. However, due to the diversity of cosmetic products and the rapid development of MS-based analytical methods, the relevant literature needs a more systematic collation of information on this subject to unravel the true potential of MS in cosmetic analysis. Herein, an overview of the role of MS in cosmetic analysis over the past two decades is presented. The currently used sample preparation methods, ionization techniques, and types of mass analyzers are demonstrated in detail. In addition, a brief perspective on the future development of MS for cosmetic analysis is provided.

Volatile Methylsiloxanes in Complex Samples: Recent Updates on Pretreatment and Analysis Methods

Volatile methylsiloxanes (VMSs) are massively produced chemicals having applications in industry and home because of their physical and chemical characteristics. They are used in personal care products such as cosmetics, household coatings, cleaners, skin care products, and others. Resultantly, large number of VMSs are discharged into air where they can be subjected to atmospheric migrations over long distances causing toxic and estrogenic effects, persistence, and bioaccumulations. Many institutions have taken measures to control VMSs. They require accurate, rapid, and sensitive pretreatment and analysis methods for diverse samples. Herein, the pretreatment and determination methods of VMSs as reported in recent years are reviewed and summarized. Pretreatments include commonly methods such as membrane-assisted solvent extraction, liquid-liquid extraction, and others, while novel methods are solid phase extraction, solid phase microextraction, diverse liquid phase microextraction and others. Analyses are made through gas chromatography-based methods. In addition, the advantages, and disadvantages of techniques are compared, and the prospects of pretreatment and analysis methods are discussed.

Basic considerations to minimize bias in collection and analysis of volatile methyl siloxanes in environmental samples

Monitoring studies that aim to quantify volatile methyl siloxanes (VMS) in environmental matrices may encounter a multitude of issues, most of which relate to the unique combination of physical-chemical characteristics of VMS that distinguish them from other classes of organic compounds. These properties, which are critical to their function in various applications, also control their fate and distribution in the environment, as well as the analytical chemistry of their measurement. Polycondensation and rearrangement reactions of VMS oligomers are possible during sample storage and analysis. Thus, care should be exercised to suppress these types of reactions by avoiding any catalytic substances or surfaces in sample collection and analysis equipment. Another factor complicating sample integrity in the analysis of trace levels of VMS, is their ubiquitous presence in many common products and components of instrumentation in the laboratory. For example, some gas chromatography columns and inlet septa have been identified as sources of VMS due to surface-catalyzed transformation of silicones to VMS promoted by moisture under high temperature in some silicone-based GC columns. Possible chemical transformation of the analytes, contamination from other sources, and potential loss of analytes need to be assessed throughout all aspects of the study, from sample collection through analysis, by establishing a rigorous quality assurance and quality control program. The implementation of such a robust QA/QC program facilitates the identification and minimization of potential analytical biases and ensures the validity and usability of data generated from environmental monitoring campaigns for VMS. The objective of this paper is to focus on aspects of collection, processing, and analysis of environmental samples that may influence the quality of the VMS analytical results. This information should then be employed in the design and implementation of future monitoring studies and can used to assess the validity of analytical results from VMS monitoring studies.

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.

Using Design of Experiments to Optimize a Screening Analytical Methodology Based on Solid-Phase Microextraction/Gas Chromatography for the Determination of Volatile Methylsiloxanes in Water

Volatile methylsiloxanes (VMSs) constitute a group of compounds used in a great variety of products, particularly personal care products. Due to their massive use, they are continually discharged into wastewater treatment plants and are increasingly being detected in wastewater and in the environment at low concentrations. The aim of this work was to develop and validate a fast and reliable methodology to screen seven VMSs in water samples, by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography with flame ionization detection (GC-FID). The influence of several factors affecting the extraction efficiency was investigated using a design of experiments approach. The main factors were selected (fiber type, sample volume, ionic strength, extraction and desorption time, extraction and desorption temperature) and optimized, employing a central composite design. The optimal conditions were: 65 µm PDMS/Divinylbenzene fiber, 10 mL sample, 19.5% NaCl, 39 min extraction time, 10 min desorption time, and 33 °C and 240 °C as extraction and desorption temperature, respectively. The methodology was successfully validated, showing low detection limits (up to 24 ng/L), good precision (relative standard deviations below 15%), and accuracy ranging from 62% to 104% in wastewater, tap, and river water samples.

Simultaneous determination of 11 antiseptic ingredients in surface water based on polypyrrole decorated magnetic nanoparticles

With the emergence and spread of coronavirus COVID-19, the use of personal cleansing, medical and household disinfectant products have increased significantly. In this work, a new magnetic solid-phase extraction (MSPE) method for the determination of 11 antiseptic ingredients in surface water by high performance liquid chromatography-mass spectrometry (HPLC-MS/MS) for 6 months based on Fe3O4@PPy magnetic nanoparticles (MNPs) was established. The MSPE method possessed the advantages of simple processing, little time consumption and less organic solvent consumption, and the MNPs could be reused several times. The analytical parameters influencing the extraction efficiency, such as sample pH, amount of MNPs and extraction time, were optimized in detail. It was indicated that the method had satisfactory linearities in the range of 0.50 to 1000.0 μg L-1 with the correlation coefficients (r) higher than 0.9996. Additionally, satisfactory spiked recoveries were achieved in the range of 80.21-107.33% with relative standard deviations (RSDs) from 1.98% to 8.05%. The limits of detection (LODs) and limits of quantitation (LOQs) were in the range of 0.20 to 2.0 μg L-1 and 0.50 to 5.0 μg L-1. Therefore, the developed MSPE-HPLC-MS/MS method has high selectivity and stability, and satisfactory quantitative capability for the antiseptic ingredients in surface water. Furthermore, this method can provide relevant technical support for the development of surface water standards.

Development of a solid-phase microextraction method for fast analysis of cyclic volatile methylsiloxanes in water

Cyclic volatile methylsiloxanes (cVMS) are widely used in consumer products and commonly detected in the environment. There are challenges in the analysis of cVMS because of their ubiquitous use which can introduce high background contamination. The current study introduces a sample preparation method based on headspace of solid-phase microextraction (SPME) for monitoring the cVMS in waters. Efforts were made to reduce the background contamination during sample preparation and instrument analysis. A laboratory prepared MIL-101 coating was prepared using polysulfone instead of polydimethylsiloxane as adhesive to avoid the contamination. The extraction performance of the MIL-101 fiber was optimized and evaluated. The optimized extraction time and temperature were 60 min and 40 °C, respectively. The method quantification limits of the MIL-101 fiber for octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecylcyclohexasiloxane (D6) in water were 0.15 ng mL^-1, 0.14 ng mL^-1, and 0.27 ng mL^-1, respectively. The extraction efficiency of the proposed MIL-101 fiber was comparable to the commercial polydimethylsiloxane/divinylbenzene fiber. The developed method was applied to analyze the cVMS in wastewater treatment plant and the concentrations in the barscreen and in the aeration tank ranged from 0.73 to 3.3 ng mL^-1 and 7.74-85.1 ng mL^-1, respectively. The MIL-101 fiber was also applied to study the photodegradation of the cVMS in water under simulated sunlight. Approximately 25%, 20%, and 45% of D4, D5, and D6, respectively, were degraded after 10 h exposure.

Headspace gas chromatography for the determination of volatile methylsiloxanes in personal care products

Most of the reported methods for the analysis of volatile methylsiloxanes focus on their environmental fate or possible health effects, aiming at trace level analysis by using direct injection gas chromatography. However, system contamination as carry over and side reactions at the injector are commonly reported in those cases. In this article, we explore the use of headspace gas chromatography combined with the total vaporization technique as an alternative to avoid such issues for the analysis of linear (L2-L5) and cyclic (D3-D5) volatile methylsiloxanes. The proposed method showed good linearity with R² values higher than 0.9961 and no significant contribution (α = 0.05) of the intercept. The limit of detection was always below 0.11 μg/vial (0.0025% m/m). Finally, the method was applied to real samples like an adhesive remover, hair oil, shampoo, and cream. After simple sample pretreatment, recoveries higher than 86% were achieved. Graphical abstract.

Marine vegetation analysis for the determination of volatile methylsiloxanes in coastal areas

Volatile methylsiloxanes (VMSs) are massively produced chemicals that comprise a wide range of industrial and household applications. The presence of cyclic and linear VMSs in several environmental matrices and ecosystems indicates persistence associated with a potential of (bio)accumulation and food web transfer with possible toxicological effects. Due to the high anthropogenic pressure in its vicinities particularly in summer, coastal areas in Southern European countries are potential hotspots for the presence of VMSs. The massive afflux of tourists and consequent increase of the use of personal care products (PCPs) with VMSs in their formulations highlight the importance of VMSs assessment in such areas. In this study, different species of marine vegetation (algae and seaweed) were collected in three different geographical areas, covering the Atlantic Ocean (North coast of Portugal), as well as the Mediterranean Sea (coasts of the Region of Murcia, Spain and of the city of Marseille, France). Samples were analysed for the determination of 4 cyclic (D3, D4, D5, D6) and 3 linear (L3, L4, L5) VMSs employing a QuEChERS extraction methodology, followed by gas chromatography/mass spectrometry (GC/MS) quantification. VMSs were detected in 92% of the 74 samples analysed, with the sum of the concentrations per sample ranging from below the limit of detection (LOD) to 458 ± 26 ng·g-1dw (dry weight). A strong predominance of cyclic VMSs over linear ones was verified in almost all samples studied, with D5 and D6 found at higher concentrations. Seasonal variation was also assessed and despite higher levels of VMSs being identified mostly in summer months, clear seasonal trends were not perceived. It was also noted that generally the higher incidence of VMSs occurred in samples from urban and industrialized areas or in the vicinities of WWTPs, suggesting a direct input from these sources in the levels of siloxanes observed.

A review of semi-volatile organic compounds (SVOCs) in the indoor environment: occurrence in consumer products, indoor air and dust

As many people spend a large part of their life indoors, the quality of the indoor environment is important. Data on contaminants such as flame retardants, pesticides and plasticizers are available for indoor air and dust but are scarce for consumer products such as computers, televisions, furniture, carpets, etc. This review presents information on semi-volatile organic compounds (SVOCs) in consumer products in an attempt to link the information available for chemicals in indoor air and dust with their indoor sources. A number of 256 papers were selected and divided among SVOCs found in consumer products (n = 57), indoor dust (n = 104) and air (n = 95). Concentrations of SVOCs in consumer products, indoor dust and air are reported (e.g. PFASs max: 13.9 μg/g in textiles, 5.8 μg/kg in building materials, 121 ng/g in house dust and 6.4 ng/m³ in indoor air). Most of the studies show common aims, such as human exposure and risk assessment. The main micro-environments investigated (houses, offices and schools) reflect the relevance of indoor air quality. Most of the studies show a lack of data on concentrations of chemicals in consumer goods and often only the presence of chemicals is reported. At the moment this is the largest obstacle linking chemicals in products to chemicals detected in indoor air and dust.

Reply to comments on "Volatile methylsiloxanes in personal care products - Using QuEChERS as a "green" analytical approach" published in Talanta 174 (2017) 156-157

Recently, Pierre Germain from CES - Silicon Europe published a comment on the paper "Volatile methylsiloxanes in personal care products - Using QuEChERS as a "green" analytical approach", raising concerns that the artefacts employed in the analysis of cyclic volatile methylsiloxanes (cVMS) were not adequately controlled, while using this example as an opportunity to emphasize the difficulties associated with siloxanes analyses in complex matrices such as personal care products (PCPs). We are now addressing these concerns and conveying some clarifications regarding the experiments performed to validate the analytical method adequately. Those details were not included in the original publication because the objective was the quantification of VMS in several PCPs.

Comment on "Volatile methylsiloxanes in personal care products - Using QuEChERS as a "green" analytical approach" by Daniela Capela, Vera Homem, Arminda Alves, Lúcia Santos

In this recent paper, Capela et al. (2016) [1] describe an analytical method for determination of volatile methylsiloxanes (VMS) in a variety of personal care products (PCPs) using QuEChERS methodology (Lehotay et al., 2010) [2]. Subsequently, this method was then used by the authors to measure VMS levels in a cross-section of PCPs to estimate average daily dermal exposure, average daily inhalation exposure, and down the drain emissions of VMS components to the environment (Capela et al., 2016) [3]. The authors are commended for selecting a broad range of sample types for the investigation and for thoroughly describing the approaches used to validate the method. However, a careful analysis of the reported cyclic volatile methylsiloxane (cVMS) concentrations raises concerns that artifacts of cVMS analysis were not adequately controlled for in the method used to determine the cVMS concentrations in PCPs. The comments presented here apply beyond this particular article and serve as an opportunity to inform other researchers about the potential pitfalls and difficulties associated with cyclosiloxane analyses, even with what might appear to be a successfully validated method, while providing examples of the concerns and precautions that must be taken into consideration whenever analyzing for cVMS in complex matrices such as PCPs.

From the shop to the drain - Volatile methylsiloxanes in cosmetics and personal care products

Organosiloxanes are widely used in the formulation of a broad range of cosmetic and personal care products (PCPs), including creams and lotions, bath soaps, shampoo and hair care products to soften, smooth, and moisten. In fact, the intensive and widespread use of organosiloxanes combined with their lipophilic nature, makes them interesting targets for future research, particularly in the toxicology area. This study focused on determining the concentration levels of these compounds in the bestselling brands of PCPs in the Oporto region (Portugal), allowing the estimation of dermal and inhalation exposure to siloxanes and the evaluation of the quantities released to the environment "down-the-drain" and to air. To accomplish this task, a QuEChERS technique ("Quick, Easy, Cheap, Effective, Rugged, and Safe") was employed to extract the siloxanes from the target PCPs, which has never been tested before. The resulting extract was analysed by gas chromatography-mass spectrometry (GC-MS). The limits of detection varied between 0.17 (L2) and 3.75ngg(-1) (L5), being much lower than any values reported in the literature for this kind of products. In general, satisfactory precision (<10%) and accuracy values (average recovery of 84%) were obtained. 123 PCPs were analysed (moisturizers, deodorants, body and hair washes, toilet soaps, toothpastes and shaving products) and volatile methylsiloxanes were detected in 96% of the samples, in concentrations between 0.003μgg(-1) and 1203μgg(-1). Shampoo exhibited the highest concentration for cyclic and aftershaves for linear siloxanes. Combining these results with the daily usage amounts, an average daily dermal exposure of 25.04μgkgbw(-1)day(-1) for adults and 0.35μgkgbw(-1)day(-1) for baby/children was estimated. The main contributors for adult dermal exposure were body moisturizers, followed by facial creams and aftershaves, while for babies/children were body moisturizers, followed by shower gel and shampoo. Similarly, the average daily inhalation exposure was also estimated. Values of 1.56μgkgbw(-1)day(-1) for adults and 0.03μgkgbw(-1)day(-1) for babies/children were calculated. An estimate of the siloxanes amount released "down-the-drain" into the sewage systems through the use of toiletries was also performed. An emission per capita between 49.25 and 9574μgday(-1) (mean: 1817μgday(-1)) is expected and shampoo and shower gel presented the higher mean total values (1008μgday(-1) and 473.3μgday(-1), respectively). In the worst-case scenario, D5 and D3 were the predominant siloxanes in the effluents with 3336μgday(-1) and 3789μgday(-1), respectively. Regarding the air emissions per capita, values between 8.33 and 6109μgday(-1) (mean: 1607μgday(-1)) are expected and D5 and D6 were the predominant siloxanes.