New developments in the extraction and determination of parabens in cosmetics and environmental samples. A review

Development and optimization of natural deep eutectic solvent-based dispersive liquid-liquid microextraction coupled with UPLC-UV for simultaneous determination of parabens in personal care products: evaluation of the eco-friendliness level of the developed method

Dispersive liquid-liquid microextraction (DLLME) combined with ultra-high performance liquid chromatography-diode array detector (UHPLC-DAD) method has been developed and validated for the determination of parabens in personal care products. In this study, a natural deep eutectic solvent (NADES) composed of menthol and formic acid at a molar ratio of 1 : 2 was prepared and used as an extraction solvent. The influencing variables on the extraction efficiency such as extraction solvent type and volume, composition of NADES, salt addition, vortex and centrifugation time were investigated. The proposed method exhibited good linearity with determination coefficients of ≥0.9992. The relative recoveries for the studied analytes ranged from 82.19 to 102.45%. Limits of detection and limits of quantification were in the range of 0.17-0.33 ng mL^-1 and 0.51-0.99 ng mL^-1, respectively. To evaluate the applicability of the developed method, it was successfully applied to determine four parabens in personal care products. Additionally, the eco-friendliness level of the presented method was evaluated using Eco-Scale Assessment, Green Analytical Procedure Index and Analytical GREEnness metric. The developed method is simple, environmentally friendly and cost effective and it could be employed for determination of parabens in personal care products without harming the environment.

Fabrication of a core-shell porphyrin-based magnetic covalent organic framework for effective extraction of PCPs in a wide polarity range

A novel porphyrin-based magnetic covalent organic framework (PCOF) was first reported by using a facile synthetic procedure. The Fe₃O₄@NH₂@PCOF nanospheres were utilized to effectively extract personal care products in a wide polarity range (log K_ow values from 1.96 to 7.60). The successful magnetic solid-phase extraction (MSPE) of target analytes could be ascribed to the sufficient oxygen-, nitrogen- and phenyl-containing functional groups of the COF layer, which are demonstrated to be of good compatibility with pollutants exhibiting different polarities by using molecular dynamics simulations, independent gradient model analysis and various characterizations. The MSPE extraction efficiency was enhanced by optimizing key parameters. The findings indicated that the method had a wide linearity range (1-500 ng mL^-1 for parabens and UV filters) and low detection limits (0.4-0.9 ng mL^-1 for parabens and 0.2-0.6 ng mL^-1 for UV filters). The accuracy was reflected by recoveries ranging from 74% to 114%. Satisfactory intra- and inter-day precisions from 3.0% to 9.8% and 0.5%-9.1% were obtained. Overall, the proposed MSPE-HPLC method is accurate and reliable for identifying parabens as well as UV filters in wastewater and swimming pool water. The potential of the method for evaluating human exposure risk was unfolded.

Development of a new strategy for the synthesis of graphene oxide-alumina nanocomposite as an efficient adsorbent for dispersive solid-phase extraction of parabens

The present study investigates the synthesis and application of the graphene oxide-alumina nanocomposite as a new adsorbent for the dispersive solid-phase extraction of three parabens and their determination using high-performance liquid chromatography-ultraviolet detection. The characterization of the synthesized material was accomplished and its size, morphology, chemical composition, porosity, and thermal stability were studied. Application of the proposed strategy for the synthesis of the nanocomposite resulted in the incorporation of Al₂ O₃ nanoparticles into graphene oxide nanosheets, further resulting in the exfoliation of graphene oxide nanosheets increasing their surface area. An orthogonal rotatable central composite design was used to optimize the extraction. Under the optimum conditions, the analytical performance of the method showed a suitable linear dynamic range (0.2-100.0 μg/L), reasonable limits of detection (0.03-0.05 μg/L), and preconcentration factors ranging from 128 to 173. Finally, the new validated method was applied for the determination of parabens in some real samples including wastewater, cream, toothpaste, and juice samples with satisfactory recoveries (88%-109%), and relative standard deviations less than 8.7% (n = 3). Results demonstrated that inserting alumina nanoparticles into graphene oxide nanosheets improved the extraction efficiency of parabens, as polar acidic compounds, by providing additional efficient interactions including hydrogen bonding, dipole-dipole, and Brønsted and Lewis acid-base interactions.

Monitoring and eco-toxicity effect of paraben-based pollutants in sediments/seawater, north of the Persian Gulf

The current work is documented as the first record of the characteristics, removal efficiency, partitioning behavior, fate, and eco-toxicological effects of paraben congeners in a municipal wastewater treatment plant (WWTP, stabilization ponds) and hospital WWTPs (septic tank and activated sludge), as well as seawater-sediments collected from runoff estuarine stations (RES) and coastal stations (CS) of the north of the Persian Gulf. The median values of Σparabens at the raw wastewater and effluent of the studied WWTPs were 1884 ng/L and 468 ng/L, respectively. The activated sludge system had a greater removal efficiency (56.10%) in removing ∑parabens than the septic tank (45.05%) and stabilization pond (35.54%). The discharge rates of methyl paraben (MeP) was computed to be 2.23, 21.18, and 9.12 g/d/1000 people for stabilization ponds, septic tank, and activated sludge, respectively. Median concentrations of Σparabens in seawater (103.42 ng/L) and sediments (322.05 ng/g dw) from RES stations were significantly larger than from CS stations (61.2 and 262.0 ng/g dw in seawater and sediments, respectively) (P < 0.05). The median of field-based k_oc for Σparabens was 130.81 cm³/g in RES stations and 189.51 cm³/g in CS stations. It was observed that the concentration of parabens could have negative impacts on some living aquatic populations (invertebrates and bacteria), but the risk was not significant for fishes and algae.

Urinary parabens and breast cancer risk: Modification by LINE-1 and LUMA global DNA methylation, and associations with breast cancer defined by tumor promoter methylation status

Parabens are a group of alkyl esters of p-hydroxybenzoic acid added to consumer products to prevent the growth of harmful bacteria and molds. Parabens are hypothesized to increase the risk of breast cancer (BC); however, no study has examined the interactions between parabens, global DNA methylation (DNAm), and BC risk. We examined the modifying effects of DNAm on the associations between parabens and BC, and whether parabens were associated with BC defined by tumor promoter methylation status. Participants included 708 cases and 598 controls from the Long Island Breast Cancer Study Project. Methylparaben (MPB), propylparaben, and butylparaben levels were measured in spot urine samples. Global DNAm was measured by analysis of long interspersed elementes-1 (LINE-1) and the luminometric methylation assay (LUMA). The promoter methylation status of 13 genes was measured in tumor samples from 509 cases. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between parabens and BC stratified by LINE-1/LUMA, and between parabens and gene-specific promoter methylation-defined BC. Outcome heterogeneity was evaluated using ratios of ORs (RORs). We assessed the joint effects of the multiple parabens using quantile g-computation. The highest versus lowest tertile of MPB and a one-quantile increase in all parabens were associated with ORs of 1.46 (95% CI = 0.96-2.23) and 1.32 (95% CI = 1.02-1.71), respectively, among women with hypomethylated LINE-1. A one-ln unit increase in MPB was associated with a 25% increase in the odds of hypomethylated (vs. hypermethylated) CCND2 promoter-defined BC (ROR = 1.25, 95% CI = 1.06-1.48), and a one-quantile increase in all parabens was associated with a 55% increase in the odds of hypomethylated (vs. hypermethylated) CCND2 promoter-defined BC (ROR = 1.55, 95% CI = 1.04-2.32). Exposure to parabens may increase the risk of BC among women with hypomethylated global DNAm and may increase the risk of tumors with gene-specific hypomethylated promoter regions.

Overview of Different Modes and Applications of Liquid Phase-Based Microextraction Techniques

Liquid phase-based microextraction techniques (LPµETs) have attracted great attention from the scientific community since their invention and implementation mainly due to their high efficiency, low solvent and sample amount, enhanced selectivity and precision, and good reproducibility for a wide range of analytes. This review explores the different possibilities and applications of LPμETs including dispersive liquid–liquid microextraction (DLLME) and single-drop microextraction (SDME), highlighting its two main approaches, direct immersion-SDME and headspace-SDME, hollow-fiber liquid-phase microextraction (HF-LPME) in its two- and three-phase device modes using the donor–acceptor interactions, and electro membrane extraction (EME). Currently, these LPμETs are used in very different areas of interest, from the environment to food and beverages, pharmaceutical, clinical, and forensic analysis. Several important potential applications of each technique will be reported, highlighting its advantages and drawbacks. Moreover, the use of alternative and efficient “green” extraction solvents including nanostructured supramolecular solvents (SUPRASs, deep eutectic solvents (DES), and ionic liquids (ILs)) will be discussed.

Development of novel thin-film solid-phase microextraction materials based on deep eutectic solvents for preconcentration of trace amounts of parabens in surface waters

A green and sensitive thin-film solid-phase microextraction method based on deep eutectic solvent was developed that enables simultaneous isolation, preconcentration, and determination of parabens in surface waters. Six new deep eutectic solvents were synthesized and used directly to prepare thin-film coatings on a stainless steel mesh support. Among the compounds obtained, the highest efficiency in the extraction of parabens was found for a material consisting of trihexyltetradecylphosphonium chloride and n-docosanol in a molar ratio of 1:2. For the proposed method, parameters affecting the extraction efficiency of parabens, such as the coating material, the desorption solvent, the volume of the sample, the pH of the sample, the extraction and desorption time, and the salting-out effect, were optimized. Under optimal conditions, the proposed method allowed us to achieve good precision between 3.6 and 6.5% and recovery ranging from 68.1 to 91.4%. The limits of detection range from 0.018 to 0.055 ng mL^-1 . This article is protected by copyright. All rights reserved.

The implication of parabens in cosmetics and cosmeceuticals: advantages and limitations

Cosmetics, cosmeceuticals, and variable healthcare products used parabens, among other excipients, for their preservative and antimicrobial activities. Paraben derivatives exhibit distinguished physiochemical properties that enable them to be compatible with the formulation of cosmetic agents in different dosage forms. In addition to their potency and efficacy, parabens are economically efficient as they have low manufacturing costs. Despite the desirable characteristics, the safety of parabens use is controversial after detecting these chemicals in various biological tissues after repetitive and long-term use of formulations containing them. The use of parabens drew public health attention after scientific reports linked skin exposure to parabens with health issues, in particular, breast cancer. In response, worldwide authorities set regulations for the allowance concentrations of paraben to be used in variable cosmetic products.

Ex-situ and in-situ rapid and quantitative determination of benzene derivatives in seawater using nanoconfined liquid phase nanoextraction

Benzene derivatives (BDs) constitute a class of environmental pollutants whose exposure poses a grave risk to human health. These compounds rapidly diffuse from the atmosphere to the marine ecosystem: for this reason, their monitoring in seawater is every day more compelling. In this work, nanoconfined liquid phase nanoextraction (NLPNE), a versatile extraction technique recently described, has been for the first time applied to the gas chromatographic mass spectrometry (GC/MS) analysis of BDs in seawater. Ex-situ and in-situ NLPNE procedures have been developed and optimized in terms of extraction capabilities, analysis time, precision, and accuracy. Compared to the traditional extraction procedures, based on solid-phase microextraction (SPME) and liquid-liquid extraction (LLE), the proposed NLPNE methods allowed a rapid on-site analysis of benzene compounds with low solvent consumption, higher enrichment factors, and improved automation grade. Determination coefficients ranging from 0.9929 to 0.9997 were obtained for all BDs in the range 0.10-500 ng mL^-1 and 5.00-500 ng mL^-1, for ex-situ and in-situ NLPNE, respectively. Ex-situ and in-situ limits of detection ranged from 0.2 to 7.6 ng mL^-1 and 0.04-1.00 ng mL^-1. Our results suggest that NLPNE coupled to GC-MS can be considered a powerful technique for high-throughput analyses of trace compounds in environmental, food and biological samples.

Toxicity and removal of parabens from water: A critical review

Parabens are biocides used as preservatives in food, cosmetics and pharmaceuticals. They possess antibacterial and antifungal activity due to their ability to disrupt cell membrane and intracellular proteins, and cause changes in enzymatic activity of microbial cells. Water, one of our most valuable natural resource, has become a huge reservoir for parabens. Halogenated parabens from chlorination/ozonation of water contaminated with parabens have shown to be even more persistent in water than other types of parabens. Unfortunately, there is dearth of data on their (halogenated parabens) presence and fate in groundwater which serves as a major source of drinking water for a huge population in developing countries. An attempt to neglect the presence of parabens in water will expose man to it through ingestion of contaminated food and water. Although there are reviews on the occurrence, fate and behaviour of parabens in the environment, they largely omit toxicity and removal aspects. This review therefore, presents recent reports on the acute and chronic toxicity of parabens, their estrogenic agonistic and antagonistic activity and also their relationship with antimicrobial resistance. This article further X-rays several techniques that have been employed for the removal of parabens in water and their drawbacks including adsorption, biodegradation, membrane technology and advanced oxidation processes (AOPs). The heterogeneous photocatalytic process (one of the AOPs) appears to be more favoured for removal of parabens due to its ability to mineralize parabens in water. However, more work is needed to improve this ability of heterogeneous photocatalysts. Perspectives that will be relevant for future scientific studies and which will drive policy shift towards the presence of parabens in our drinking waters are also offered. It is hoped that this review will elicit some spontaneous actions from water professionals, scientists and policy makers alike that will provide more data, effective technologies, and adaptive policies that will address the growing threat of the presence of parabens in our environment with respect to human health.

DFT investigation of SiO2 nanotube for adsorption of methyl- and propyl-paraben

A huge number of parabens, esters of p-hydroxybenzoic acid, are used in cosmetic and personal care products as preservative substances. Due to their detrimental effects on ecosystem and human health, taking precautionary measures to remove these compounds is an important task regarding the environmental issues. In this study, a silica (SiO2) nanotube has been selected as a novel sensor to adsorb the most common parabens which are methyl paraben and propyl paraben molecules. To this aim, density functional theory (DFT) calculations were used to evaluate the properties for investigated compounds. The calculated adsorption energies of the most stable configurations for methyl parban@SiO2 and propyl paraben@SiO2 complexes were found to be –0.238 and –0.242 eV, respectively. The electronic properties of nanotubes experienced dramatic changes in case of interactions with parabens, which led to declining the HOMO/LUMO energy gap of the nanotube to its original value. Such adsorption could also enhance the electrical conductivity of the nanotubes meaning that the utilized SiO2 nanotube could detect the existence of methyl and propyl parabens molecules in the environment. As a concluding remark, the investigated SiO2 nanotube could work as a possible sensor for hazardous paraben with the importance of environmental issues.

Parabens and bisphenol A and its structural analogues in over-the-counter medicines from China

Pharmaceuticals, such as over-the-counter (OTC) medicines, may be an important source of human exposure to several endocrine disruptors, though unnoticed to date. In the present study, we investigated the presence of six parabens and nine bisphenol A (BPA) and its analogues in OTC medicines manufactured in China. Parabens and bisphenols were present in more than 90% of the samples. The total measured concentrations of parabens and bisphenols were in the range of non-detectable (ND) to 213 ng/g and ND to 415 ng/g, respectively. Regarding parabens, methyl paraben (MeP) was the predominant analog, accounting for 43 ± 36% of the total amount, followed by ethyl paraben (EtP) (39 ± 35%), and others (< 10%). Bisphenol F and BPA were the predominant bisphenols, accounting for 24 ± 28% and 22 ± 26% of the total amount, respectively. The median values of estimated daily intakes (EDIs) of parabens and bisphenols were the highest for infants (2.96 and 3.14 ng/kg_bw/day, respectively) and the lowest for adults (0.69 and 0.25 ng/kg_bw/day, respectively); moreover, the EDIs of parabens and bisphenols were higher in Chinese patent medicines than in western pediatric medicines. The hazard quotient (HQ) for sum of MeP and EtP (∑(MeP + EtP)) and BPA in three age groups were within the safe zone (HQ < 0.0004). Monte Carlo simulation was applied to predict the human exposure risk of parabens and bisphenols. The predicted ranges of EDIs of parabens and bisphenols were much wider, and the extreme predicted values were observed in all four age groups, which were higher than the acceptable daily intake. The extreme predicted values of ∑(MeP + EtP) and BPA were indicative of carcinogenic risk in toddlers. These results implied potential risks for the Chinese people existed. Considering the huge export of Chinese traditional medicines and western medicines worldwide, and easy access to OTC medicines for the general population, the presence of parabens, bisphenols, and other environmental contaminants in medicines still need to be monitored.

Determination of six parabens in biological samples by magnetic solid-phase extraction with magnetic mesoporous carbon adsorbent and UHPLC-MS/MS

Although parabens are useful due to their antiseptic properties, their widespread use has caused concerns regarding their potential toxicological effects. In this study, a novel magnetic solid-phase extraction combined with ultra-high-performance liquid chromatography-tandem mass spectrometry (MSPE-UHPLC-MS/MS) was developed, based on ordered magnetic mesoporous carbon (MMC), for paraben analysis. The MMC was prepared by soft-template synthesis, with a unique pore structure and a highly specific surface response, indicating potential as an excellent adsorbent. Several parameters affecting the paraben extraction efficiency were investigated and a novel method for paraben analysis in serum and urine samples using MSPE-UHPLCMS/MS was developed. The concentrations of methylparaben, ethylparaben, isopropylparaben, and propylparaben in these samples were 0.0380-4.36, 0.460-9.65, 0.0118-0.770, and 0.0363-0.641 μg/L, respectively, whereas isobutylparaben and butylparaben were not detected. Furthermore, satisfactory recoveries of 76.4-121% with relative standard deviations (n = 5) of 1.9-8.6% were obtained. Therefore, the developed MSPE-UHPLC-MS/MS method was efficient, highly sensitive, and reliable for analysing parabens in complex biological samples.

Experimental design approaches to optimize ultrasound-assisted simultaneous-silylation dispersive liquid-liquid microextraction for the rapid determination of parabens in water samples

This work describes a rapid solvent-minimized process to effectively determine four common paraben preservatives (methyl-, ethyl-, propyl- and butyl-paraben) in surface water samples. The method involved the use of a combination of a novel ultrasound-assisted simultaneous-silylation within dispersive liquid–liquid microextraction (UASS-DLLME) with detection by gas chromatography-tandem mass spectrometry (GC-MS/MS). To overcome the challenges related to the different experimental conditions, multivariate experimental design approaches conducted by means of a multilevel categorical design and a Box–Behnken design were utilized to screen and optimize parameters that have significant influences on the efficiency of silylation and extraction. The method was then validated and shown to provide low limits of quantitation (LOQs; 1–5 ng L⁻¹), high precision (3–11%), and satisfactory mean spiked recoveries (accuracy; 79–101%). Upon analyzing samples of surface water obtained from the field, we found that, in total, there was a relatively high concentration of the target parabens ranging from 200 to 1389 ng L⁻¹. The sources of the elevated levels of these parabens may be from the release of untreated municipal wastewater in this region, and also due to the widespread application of parabens in personal care and food products.

This work describes a rapid solvent-minimized process to effectively determine four common paraben preservatives (methyl-, ethyl-, propyl- and butyl-paraben) in surface water samples.

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.

Development and Validation of a Simple HPLC-UV Method to Assay DEET Repellents and its Application to Different Commercial Forms

Background:

N’,N’-diethyl-m-toluamide (DEET) is the most widely used repellent substance worldwide. It is formulated as aerosol, solution, lotion, gel and patches. However, the official compendia report monographs to analyze only DEET drug substance and solution.

Objective:

In this study an isocratic HPLC method was validated to assay DEET in lotion, gel and solution, under the same analytical conditions.

Methods:

The method was validated according to ICH requirements and DEET detection was achieved at around 11 min, using a C-18 column, a mobile phase composed by methanol, acetonitrile and water pH 4.5 (45:10:45), flow rate at 1 mL min-1and detection at 270 nm.

Results:

A linear relationship was observed in the range of 2.5 to 100 μg mL-1, the method was precise (relative standard deviation<2%) and accuracy was demonstrated by DEET recovery values ranging from 99.5 to 100.2%. The specificity was studied by a forced degradation test, where degradation products were observed after alkaline degradation and ultraviolet radiation. Appropriate resolution between DEET, degradation products and excipient peaks indicated the method specificity. Robustness was evaluated by a full factorial design, and no effect on DEET assay was observed under simultaneous variation in analytical parameters. The method was applied to assay nine marketed formulations, demonstrating its good applicability.

Conclusion:

The validated HPLC method was successfully applied to the quantitative analysis of DEET in lotion, gel and solution, contributing to improve the quality control and the efficacy of these formulations.

Microextraction by packed sorbent optimized by statistical design of experiment as an approach to increase the sensitivity and selectivity of HPLC-UV determination of parabens in cosmetics

A new approach to the quantitative analysis of parabens (PBs) in cosmetics, based on microextraction by packed sorbent (MEPS) followed by HPLC-UV detection is proposed. The development of optimal conditions for the sample preparation step was carried out in two stages. The potentially important factors that could influence the extraction were screened using the Plackett-Burman design approach, as a result of which, three statistically significant factors were selected from the nine studied. Thereafter, the selected variables were optimized by response surface methodology using a Central Composite Design. Under optimal conditions, the linear ranges for PBs analysis in cosmetic samples were 0.05-4 μg/mL with excellent precision. Limits of detection (LOD) of PBs in cosmetic samples were 2-5 ng/mL, and the extraction recovery ranged from 89 to 105 %. By comparing the chromatograms of the diluted shampoo sample before and after MEPS, the benefits of developed approach were shown. Then it was applied to the analysis of PBs in commercial hair cosmetic products: parabens were determined in all samples in which they were indicated on the package and in 1 of 12 samples labeled "paraben-free". Finally, the proposed method was compared with other analytical HPLC-UV methods with various sample pretreatment techniques for PBs analysis in cosmetics described in recent articles. Its sensitivity turned out to be one of the highest, while it is express, automated, meets the principles of green chemistry.

Identification of novel paraben-binding peptides using phage display

Parabens are alkyl esters of 4-hydroxybenzoic acid, which is derived from a family of synthetic esters of p-hydroxybenzoic acid. Among all the kinds of paraben, two parabens (methyl paraben, MP; and n-propyl paraben, PP) are the most generally used as preservatives in personal care products, such as cosmetics, pharmaceuticals, and food also, and are often presented together. However, a number of studies have reported that the toxicity of parabens affects the water environment, and human as well. This study utilized M13 phage display technology to provide easy, efficient, and relatively inexpensive methods to identify peptides that bind to MP and PP, respectively, to remove in wastewater. At first, biopanning was performed, to sort MP and PP specific binding phages, and three cases of experiment, including negative control (NC), which could sort unspecific binding phage, were conducted at the same time. Phage binding affinity tests were substituted by concentration reduction using antibody conjugated magnetic beads, and paraben concentration was measured by HPLC. Analysis showed that the MP concentration reduction of 38% was the highest in M4 phage, while the PP concentration reduction of 44% was the highest in P3 phage. We successfully screened two peptides specific to MP and PP, namely, MP4 and PP3, respectively; the results showed that the MP concentration reduction in MP4 was the highest at 44%, and the PP concentration reduction in PP3 was the highest at 39%, and their specificity was measured by the capture rate between target and control. In conclusion, the phage display technique shows applicability to the removal of parabens in water; furthermore, it also shows the possibility of the detection or removal of other chemicals.

Simultaneous Determination of Isothiazolinones and Parabens in Cosmetic Products Using Solid-Phase Extraction and Ultra-High Performance Liquid Chromatography/Diode Array Detector

Isothiazolinones methylisothiazolinone (MI) and methylchloroisothiazolinone (MCI), and parabens methylparaben (MP), ethylparaben (EP), propylparaben (PP) and butylparaben (BP) are the most common synthetic preservatives. They are all known to be potential skin allergens that lead to contact dermatitis. Thus, the identification of these unsafe chemicals in cosmetic products is of high importance. In the present study, solid-phase extraction (SPE) based on HyperSep reversed-phase C8/benzene sulfonic acid ion exchanger (HyperSep C8/BSAIE) and Sep-Pak C18 sorbents, and ultra-high performance liquid chromatography/diode array detector (UHPLC/DAD) were optimized for the simultaneous determination of MI, MCI, MP, EP, PP and BP in cosmetic products. HyperSep C8/BSAIE and UHPLC/DAD with the eluting solvent mixture (acetonitrile/methanol, 2:1, v/v) and detection wavelength (255 nm) were found to be the optimal conditions, respectively. The method illustrates the excellent linearity range (0.008–20 μg/mL) with coefficient of determination (R², 0.997–0.999), limits of detection (LOD, 0.001–0.002 μg/mL), precision in terms of relative standard deviation (RSD < 3%, intra-day and <6%, inter-day) when examining a standard mixture at low (0.07 µg/mL), medium (3 µg/mL) and high (15 µg/mL) concentrations. A total of 31 cosmetic samples were studied, achieving concentrations (MI, not detected (nd)-0.89 µg/g), (MCI, nd-0.62 µg/g), (MP, nd-6.53 µg/g), (EP, nd-0.90 µg/g), (PP, nd-9.69 µg/g) and (BP, nd-17.80 µg/g). Recovery values ranged from 92.33 to 101.43% depending on the types of sample. To our knowledge, this is the first specific method which covers the theme and describes background amounts of such preservatives in cosmetics.

Synthesis of Magnetic Molecularly Imprinted Polymer Sorbents for Isolation of Parabens from Breast Milk

Magnetic molecularly imprinted polymers (MMIPs) are an invaluable asset in the development of many methods in analytical chemistry, particularly sample preparation. Novel adsorbents based on MMIPs are characterized by high selectivity towards a specific analyte due to the presence of a specific cavity on their polymer surface, enabling the lock-key model interactions to occur. In addition, the magnetic core provides superparamagnetic properties that allow rapid separation of the sorbent from the sample solution. Such a combination of imprinted polymers with a magnetic core has an innovative influence on the development of separation techniques. Hence, the present study describes the synthesis of MMIPs with 17β-estradiol used as a template molecule in the production of imprinted polymers. The as-prepared sorbent was used for a sorption/desorption study of five parabens from breast milk samples. The obtained results were characterized by sorption efficiency exceeding 92%, which shows the high affinity of the analytes to the functional groups on the sorbent. The final determination of the selected analytes was done with high-performance liquid chromatography using a fluorometric detector. The determined linearity ranges for selected parabens were characterized by high determination coefficients (r² from 0.9992 to 0.9999), and the calculated limit of detection (LOD) and limit of quantification (LOQ) for the identified compounds were low (LOD from 1.1-2.7 ng mL^-1; LOQ from 3.6-8.1 ng mL^-1), which makes their quantitative analysis in real samples feasible.

Optimization of double-vortex-assisted matrix solid-phase dispersion for the rapid determination of paraben preservative residues in leafy vegetables

The extensive use of preservatives during the growth, transport and storage of vegetables has been a concern because of their known or suspected toxicity that jeopardizes human health. This paper reports the development of a technique that rapidly determines the presence of five paraben preservative residues in leafy vegetables using double-vortex-assisted matrix solid-phase dispersion (DVA-MSPD) and UHPLC-electrospray ionization(-)-quadrupole time-of-flight mass spectrometry detection. We simplified the original MSPD technique by eliminating the use of mortar/pestle and SPE-column procedures. The DVA-MSPD factors were screened by a multilevel categorical design, and then optimized by Box-Behnken Design plus response surface methodology. The limits of quantification were 1.2-1.8 ng g-1 (dry weight). The satisfactory average recoveries were 85-104% with RSDs less than 10%. The developed method was successfully employed for the rapid determination of selected paraben residues at trace-level in leafy vegetable samples.

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.

Factorial Design Optimisation of Solid Phase Extraction for Preconcentration of Parabens in Wastewater Using Ultra-High Performance Liquid Chromatography Triple Quadrupole Mass Spectrometry

Background:

Parabens are synthetic esters used extensively as preservatives and/or bactericides in personal care personal products.

Objective:

Development and validation of a novel robust chemometric assisted analytical technique with superior analytical performances for the determination of ethylparaben, methylparaben and propylparaben, using simulated wastewater matrix.

Methods:

An automated Solid Phase Extraction (SPE) method coupled with liquid chromatographymass spectrometry was applied in this study. A gradient elution programme comprising of 0.1% formic acid in deionised water (A) and 0.1% formic acid in Methanol (B) was employed on a 100 x 2.1 mm, 3.0 μm a particle size biphenyl column. Two-level (2k) full factorial design coupled with response surface methodology was used for optimisation and investigation of SPE experimental variables that had the most significant outcome of the analytical response.

Results:

According to the analysis of variance (ANOVA), sample pH and eluent volume were statistically the most significant parameters. The method developed was validated for accuracy, precision, Limits of Detection (LOD) and Limit of Quantification (LOQ) and linearity. The LOD and LOQ established under those optimised conditions varied between 0.04-0.12 μgL−1 and 0.14-0.40 μgL−1 respectively. The use of matrix-matched external calibration provided extraction recoveries between 78-128% with relative standard deviations at 2-11% for two spike levels (10 and 100 μgL-1) in three different water matrices (simulated wastewater, influent and effluent water).

Conclusion:

The newly developed method was applied successfully to the analyses of parabens in wastewater samples at different sampling points of a wastewater treatment plant, revealing concentrations of up to 3 μgL−1.

Novel MIPs-Parabens based SPE Stationary Phases Characterization and Application

In this work, the synthesis, characterization, and application of novel parabens imprinted polymers as highly selective solid-phase extraction (SPE) sorbents have been reported. The imprinted polymers were created using sol–gel molecular imprinting process. All the seven parabens were considered herein in order to check the phase selectivity. By means of a validated HPLC-photodiode array detector (PDA) method all seven parabens were resolved in a single chromatographic run of 25 min. These SPE sorbents, in-house packed in SPE empty cartridges, were first characterized in terms of extraction capability, breakthrough volume, retention volume, hold-up volume, number of theoretical plates, and retention factor. Finally, the device was applied to a real urine sample to check the method feasibility on a very complex matrix. The new paraben imprinted SPE sorbents, not yet present in the literature, potentially encourage the development of novel molecularly imprinted polymers (MIPs) to enhance the extraction efficiency, and consequently the overall analytical performances, when the trace quantification is required.

Dual-vortex-assisted matrix solid-phase dispersion coupled with isotope-dilution ultrahigh-performance liquid chromatography-high resolution mass spectrometry for the rapid determination of parabens in indoor dust samples

A reliable and straightforward method was developed for the rapid determination of nine parabens (methyl-, ethyl-, propyl-, butyl-, isopropyl-, isobutyl-, pentyl-, hexyl-, and benzyl-parabens) in indoor dust by a mortar/pestle-free and column-free dual-vortex-assisted matrix solid-phase dispersion (DVA-MSPD) technique. After that, they were determined by isotope-dilution ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-qTOF-MS, or called UHPLC-HRMS) and operating in negative electrospray ionization mode. Optimization of the DVA-MSPD was done using Box-Behnken Design along with response surface methodology. Validation was done by measuring and calculating selectivity, limits of detection (LOD), limits of quantitation (LOQs), precision and trueness (accuracy) of intra- and inter-day analysis. The LOQs of the method ranged from 0.9 to 2.8 ng/g. High precisions for both intra- and inter-day analysis were obtained ranging from 1 to 8%. Excellent trueness (or mean extraction recovery) varied from 93 to 104%. The DVA-MSPD combined with isotope-dilution UHPLC-qTOF-MS was successfully applied to determine parabens in indoor dust samples from office rooms and private houses, and the total concentrations ranged from 55 to 686 ng/g.

State-of-the-art on the technique of dispersive liquid-liquid microextraction

Dispersive liquid-liquid microextraction is a new sample pretreatment technology based on traditional liquid liquid extraction. In this paper, the application of low-toxicity extractants such as low-density extractants, auxiliary extractants, stripping agents and ionic liquids in this technology and the extraction modes such as solvent de-emulsification, suspension extractant curing, auxiliary extraction, back extraction, and ionic liquid-dispersion liquid microextraction, are summarized. In addition, the synergism of this technique with other sample preparation techniques, such as liquid-liquid extraction, solid-phase extraction, solid-phase microextraction, dispersive solid phase extraction, matrix solid-phase dispersion extraction, supercritical fluid extraction and ultrasound-assisted dispersive liquid-liquid microextraction is discussed.

A study on the removal of propyl, butyl, and benzyl parabens via newly synthesised ionic liquid loaded magnetically confined polymeric mesoporous adsorbent

This study investigated the effectiveness of ionic liquids (ILs) loaded onto the surface of a polymeric adsorbent (βCD-TDI) grafted with modified magnetic nanoparticles (MNPs) via an analysis of water treatment, which resulted in high removal of selected endocrine-disrupting chemicals (parabens). The syntheses of MNPs, MNP-βCD-TDI, and IL-MNP-βCD-TDI were characterised and compared using Fourier transform infrared (FT-IR) spectroscopy, carbon-hydrogen-nitrogen (CHN) analysis, vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), the Brunauer-Emmett-Teller (BET) method, thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The results of SEM and TEM indicated that the pore size distribution exhibited mesoporous characteristics with a small surface area (BET analysis: 42.95 m2 g-1). Furthermore, a preliminary sorption experiment demonstrated the ability of IL-MNP-βCD-TDI to enhance not only the sorption capacity, but also the removal of propyl paraben (PP), butyl paraben (BP), and benzyl paraben (ArP). The adsorption process appeared to be pH-dependent, and hence the optimum pH of 6 was selected for a subsequent batch adsorption study of all the studied parabens with an equilibrium time of 80 min. Next, in an attempt to investigate the interactions that occur between the adsorbent and the adsorbates, adsorption kinetics and isotherm studies were performed. All the studied parabens were found to best fit pseudo-second-order kinetics and the Freundlich isotherm with R 2 > 0.98 at room temperature (298 K). The interaction of the host-guest inclusion complex and the π-π interaction between βCD and a selected paraben compound (ArP) were identified by performing 1H nuclear magnetic resonance (NMR), together with ultraviolet-visible (UV-vis) spectroscopic analysis. Finally, the adsorption efficiency of the developed material was practically tested on tap water, drain water, and industrial wastewater, which revealed a significant removal of parabens of up to 60-90% in comparison with a prior analysis.