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

Rhodamine and related substances in food: Recent updates on pretreatment and analysis methods

Rhodamine, a colorant prohibited in various consumer products due to its demonstrated carcinogenic, mutagenic, and toxic properties, necessitates the development of a straightforward, efficient, sensitive, environmentally friendly, and cost-effective analytical method. This review provides an overview of recent advancements in the pretreatment and determination techniques for rhodamine across diverse sample matrices since 2017. Sample preparation methods encompass both commonly used pretreatment techniques such as filtration, centrifugation, solvent extraction, and cloud point extraction, as well as innovative approaches including solid phase extraction, dispersive liquid-liquid microextraction, hollow fiber liquid phase microextraction, magnetic solid phase extraction, and matrix solid phase dispersion. The analytical techniques encompass high performance liquid chromatography, surface-enhanced Raman scattering, and sensor-based methods. Furthermore, a comprehensive examination is conducted to offer insights for future research on rhodamine regarding the advantages, disadvantages, and advancements in various pretreatment and determination methodologies.

Mass-Spectrometry-Based Research of Cosmetic Ingredients

Cosmetic products are chemical substances or mixtures used on the skin, hair, nails, teeth, and the mucous membranes of the oral cavity, whose use is intended to clean, protect, correct body odor, perfume, keep in good condition, or change appearance. The analysis of cosmetic ingredients is often challenging because of their huge complexity and their adulteration. Among various analytical tools, mass spectrometry (MS) has been largely used for compound detection, ingredient screening, quality control, detection of product authenticity, and health risk evaluation. This work is focused on the MS applications in detecting and quantification of some common cosmetic ingredients, i.e., preservatives, dyes, heavy metals, allergens, and bioconjugates in various matrices (leave-on or rinse-off cosmetic products). As a global view, MS-based analysis of bioconjugates is a narrow field, and LC- and GC/GC×GC-MS are widely used for the investigation of preservatives, dyes, and fragrances, while inductively coupled plasma (ICP)-MS is ideal for comprehensive analysis of heavy metals. Ambient ionization approaches and advanced separation methods (i.e., convergence chromatography (UPC2)) coupled to MS have been proven to be an excellent choice for the analysis of scented allergens. At the same time, the current paper explores the challenges of MS-based analysis for cosmetic safety studies.

Synthetic dyes: A mass spectrometry approach and applications

Synthetic dyes are found in a wide variety of applications today, including but not limited to textiles, foods, and medicine. The analysis of these molecules is pertinent to several fields such as forensics, environmental monitoring, and quality control, all of which require the sensitivity and selectivity of analysis provided by mass spectrometry (MS). Recently, there has been an increase in the implementation of MS evaluation of synthetic dyes by various methods, with the majority of research thus far falling under electrospray ionization and moving toward direct ionization methods. This review covers an overview of the chemistry of synthetic dyes needed for the understanding of MS sample preparation and spectral results, current fields of application, ionization methods, and fragmentation trends and works that have been reported in recent years.

A study on the applicability of one-step vortex extraction and purification combined with gas chromatography-tandem mass spectrometry for analysis of four skin penetration enhancers in cosmetics

Based on one-step vortex extraction and purification combined with gas chromatography-tandem mass spectrometry (GC-MS/MS), we established a simple, rapid, and efficient method for the simultaneous determination of four skin penetration enhancers in cosmetics, including isosorbide dimethyl ether, isopropyl myristate, N-butylsaccharin and Azone. The extraction procedure was performed in a centrifuge tube, allowing extraction and purification in a single step. The cosmetic sample was extracted by n-hexane-ethyl acetate (1:1, V/V), purified by silica gel and anhydrous magnesium sulfate as the solid phase purification agent, separated on a TG-5 ms column (30.0 m × 0.25 mm × 0.25 μ m), confirmed and detected by GC-MS/MS in the selected reaction monitoring (SRM) mode, and quantified by the internal standard method with Di-n‑butyl phthalate-D4(DBP-D4) as the internal standard. The selections of a column, extraction solvent, and solid phase purification agent were optimized. Under the optimized conditions, the four skin penetration enhancers showed good linearities in the range of 0.02∼0.50 mg L - 1. The correlation coefficients (r) were 0.992 ∼ 0.997, exceeding the specifications requirements (r ≥ 0.990); The detection (LODs, S/N = 3) and quantification limits (LOQs, S/N = 10) of the method were 0.08 ∼ 0.12 mg kg-1 and 0.25 ∼ 0.40 mg kg-1, respectively. According to the cosmetic matrix in different formulation systems, the spiked recovery tests were carried out at three levels, i.e., low, medium, and high. The average recoveries of the analytes were 85.3% ∼ 95.6%, and the relative standard deviations (RSDs, n = 6) were 2.1% ∼ 7.8%. The established method was also employed to analyze cosmetics in the market. Azone, isosorbide dimethyl ether, and isopropyl myristate resulted as the most widely used skin penetration enhancers in cosmetics. The method established in this study has the advantages of operational simplicity, high sensitivity, good reproducibility, and low consumption of samples and solvents. Moreover, it can be used to determine skin penetration enhancers in cosmetics.

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.

Analysis of Prohibited and Restricted Ingredients in Cosmetics

The general public uses cosmetics daily. Cosmetic products contain substances (ingredients) with various functions, from skincare to enhancing appearance, as well as ingredients that preserve the cosmetic products. Some cosmetic ingredients are prohibited or restricted in certain geographical regions, such as the European Union and the United States of America, due to their potential to cause adverse effects such as cancer, birth defects, and/or developmental and reproductive disorders. However, the ingredients may be used in other regions, and, hence, the monitoring of the cosmetic ingredients actually used is important to ensure the safety of cosmetic products. This review provides an overview of recent analytical methods that have been developed for detecting certain ingredients that are restricted or prohibited by the U.S. Food and Drug Administration (FDA) and/or EU legislation on cosmetic products.

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.

High-Resolution Mass Spectrometry for the Comprehensive Characterization of Plant-Pigment-Based Tattoos and Dyes Formulations

There has been little research on emerging natural-pigment-based temporary tattoos and their constituents so far. This study focused on the characterization of natural henna and jagua tattoos and dyes in commercial samples. Sample manipulation and treatment were minimal to analyze natural pigments as they are marketed. The characterization of active compounds was performed by ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS). A novel untargeted characterization was also applied for these types of samples, searching for compounds ranging from the original ingredients to other additives of interest they may contain. The fact that these products may also be a source of unlabelled allergens was considered. This work showed that not all of the 34 samples analyzed contained their characteristic active ingredients, and in addition, 70 substances of a different nature were found. Therefore, a rapid and high-throughput methodology has been developed for the identification of the components of these dyes, providing a necessary approach for quality control or identification of suspicious substances.

Micro Salting-Out Assisted Matrix Solid-Phase Dispersion: A Simple and Fast Sample Preparation Method for the Analysis of Bisphenol Contaminants in Bee Pollen

In the present work, a novel sample preparation method, micro salting-out assisted matrix solid-phase dispersion (μ-SOA-MSPD), was developed for the determination of bisphenol A (BPA) and bisphenol B (BPB) contaminants in bee pollen. The proposed method was designed to combine two classical sample preparation methodologies, matrix solid-phase dispersion (MSPD) and homogenous liquid-liquid extraction (HLLE), to simplify and speed-up the preparation process. Parameters of μ-SOA-MSPD were systematically investigated, and results indicated the significant effect of salt and ACN-H₂O extractant on the signal response of analytes. In addition, excellent clean-up ability in removing matrix components was observed when primary secondary amine (PSA) sorbent was introduced into the blending operation. The developed method was fully validated, and the limits of detection for BPA and BPB were 20 μg/kg and 30 μg/kg, respectively. Average recoveries and precisions were ranged from 83.03% to 94.64% and 1.76% to 5.45%, respectively. This is the first report on the analysis of bisphenol contaminants in bee pollen sample, and also on the combination of MSPD and HLLE. The present method might provide a new strategy for simple and fast sample preparation of solid and semi-solid samples.

Determination of multi-class polyaromatic compounds in sediments by a simple modified matrix solid phase dispersive extraction

A simple, efficient matrix solid phase dispersive extraction (MSPD) method was optimised to analyse simultaneously polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs) from sediments, and was compared to microwave-assisted extraction (MAE). New dispersing agents were tested to improve MSPD extraction. 3-chloropropyl-bonded silica particles, in addition to Florisil, increased significantly the polyaromatics desorption capacity. A compromise was found for eluting both families of compounds from sediments, using a small volume of hexane/acetone. Low procedural detection limits could be reached (0.06-0.22 ng g^-1 and 0.3-1.1 ng g^-1 for PAHs and PCBs, respectively). Mean total extraction recoveries were good for PAHs (>67%, depending on the sediment) and for PCBs (>89%), with good precision (6-9% and 4-10% inter-day precision for PAHs and PCBs, respectively). Higher recoveries for PCBs could be reached in comparison with formerly developed sonication or Soxhlet extraction methods, but also with MAE. MSPD offered significant decrease of sample amount, of solvent consumption and allowed more efficient cleaning of the sediment matrix, leading to less matrix effects compared to MAE, removing lots of interfering compounds without additional purification step. The robustness of the MSPD methodology could be demonstrated extracting quantitatively sediments from different sources and with various mineralogical characteristics.

A composite polymer of polystyrene coated with poly(4-vinylpyridine) as a sorbent for the extraction of synthetic dyes from foodstuffs

A poly(St-co-EGDMA)@poly(4-vinylpyridine-co-EGDMA) composite polymer was synthesised by precipitation reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymer was investigated as a sorbent for extraction of synthetic food dyes: ponceau 4R, tartrazine, sunset yellow, brilliant blue and erythrosine from soft drinks. The morphology and composition of the polymer were characterized and confirmed respectively by scanning electron microscopy and Fourier-transform infrared spectroscopy. The pH dependence experiment revealed that the adsorption of food dyes by the polymer was pH dependent and the maximum adsorption was achieved at pH 3. Adsorption between the polymer and the dyes was mainly due to electrostatic interaction. Under the optimized pH conditions, the polymer was saturated with the dye solutions at a concentration of about 200 μg mL-1 and exhibited a maximum adsorption capacity of 9 μg mg-1. The values were higher than those for polyamide, a sorbent used in the standard method. The recovery from the real samples of the three spiked concentrations 10, 50 and 100 μg mL-1 was respectively within the ranges of 83.2-107.2%, 94.5-110.7% and 79.2-111.5%, with a SD within ±4%. The sorbent could be reused more than 10 times with a recovery higher than 80%. The small volume requirement of the sample and sorbent during the sample pre-treatment, indicated that poly(St-co-EGDMA)@poly(4-vinylpyridine-co-EGDMA) was a potential material for food dye extraction in an environment-friendly and economical manner.

A simple solvent extraction and ultra-performance liquid chromatography-tandem mass spectrometric method for the identification and quantification of rhodamine B in commercial lip balm samples

Rhodamine B is a synthetic dye used in many industries including cosmetics. Long-term contact may results neurotoxicity, genotoxicity and cancer. In the present work, a simple solvent extraction followed by rapid, sensitive and selective ultra-performance liquid chromatography-tandem mass spectrometric method has been proposed for the identification and quantification of rhodamine B in lip balm samples for the first time to our knowledge. The best extraction was achieved using organic solvent n-hexane followed by sonication, centrifugation and evaporation. The chromatographic separation was attained in <1 min with Acquity™ BEH C₁₈ reversed phase column and a tandem mass spectrometer. The limit of detection (LOD), limit of quantification (LOQ), linearity, precisions and accuracy of the proposed method were determined. The LOD and LOQ were found to be 0.1 μg/kg and 0.4 μg/kg, respectively. The linearity (R²) was obtained (>0.999) when analyzing low to higher range of concentrations. The precisions with relative standard deviation (RSD%) values in terms of repeatability (<2%, n = 5) and reproducibility (<3%, n = 5) were achieved. The accuracy in terms of recovery was obtained between 93% and 98%. The optimized procedures have been applied for the identification and quantification of rhodamine B in commercial lip balm samples from various brands and origin, and the amounts were obtained from not detected to 70.44 μg/kg. The good quality conditions, negligible matrix influence and higher recovery values obtained throughout analysis have proved the suitability of the present method for the routine analysis of rhodamine B in lip balm samples. The achieved results could be used to approximate the application of rhodamine B from individuals either from Saudi Arabia or globally, and thus to improve the quality and safety of lip balm products.

In Situ Creation of Surface-Enhanced Raman Scattering Active Au-AuO x Nanostructures through Electrochemical Process for Pigment Detection

Roughing the metallic surface via oxidation-reduction cycles (ORC) to integrate the surface plasmon resonance and surface-enhanced Raman scattering (SERS) is predominant in developing sensor systems because of the facile preparation and uniform distribution of nanostructures. Herein, we proposed a distinctive ORC process: the forward potential passed through the oxidation of Au and reached the oxygen evolution reaction, and once the potential briefly remained at the vertex, the various reverse rates were employed to control the reduction state. The created hybrid Au-AuO _x possessed electromagnetic and chemical enhancements concurrently, wherein the rough surface provided the strong local electromagnetic fields and significant interaction between AuO _x and molecule to improve the charge transfer. The synergistic effects significantly amplified the intensity of Raman signal with an enhancement factor of 5.5 × 10⁶ under the optimal conditions. Furthermore, the prepared SERS substrate can simultaneously identify and quantify the mixed edible pigments, Brilliant Blue FCF and Indigo Carmine, individually. This result suggested that the development of SERS sensor based on the proposed SERS-activated methodology is feasible and reliable.

A Comparative Study of Advanced Stationary Phases for Fast Liquid Chromatography Separation of Synthetic Food Colorants

Food analysis demands fast methods for routine control and high throughput of samples. Chromatographic separation enables simultaneous determination of numerous compounds in complex matrices, several approaches increasing separation efficiency and speed of analysis were involved. In this work, modern types of column with monolithic rod or superficially porous particles were employed and compared for determination of eight synthetic food dyes, their chromatographic performance was evaluated. During method optimization, cyano stationary phase Chromolith Performance CN 100 × 4.6 mm and Ascentis Express ES-CN 100 × 4.6 mm, 5 µm were selected for the separation of polar colorants. The separation was performed by gradient elution of acetonitrile/methanol and 2% water solution of ammonium acetate at flow rate 2.0 mL min-1. Mobile phase composition and the gradients were optimized in order to enable efficient separation on both columns. The method using fused-core particle column provided higher separation efficiency, narrow peaks of analytes resulted in increased peak capacity and shortening of analysis time. After the validation, the method was applied for analysis of coloured beers, soft drinks and candies.

A Review on the Recent Progress in Matrix Solid Phase Dispersion

Matrix solid phase dispersion (MSPD) has proven to be an efficient sample preparation method for solid, semi-solid, and viscous samples. Applications of MSPD have covered biological, food, and environmental samples, including both organic and inorganic analytes. This review presents an update on the development of MSPD in the period 2015~June 2018. In the first part of this review, we focus on the latest development in MSPD sorbent, including molecularly imprinted polymers, and carbon-based nanomaterials etc. The second part presents the miniaturization of MSPD, discussing the progress in both micro-MSPD and mini-MSPD. The on-line/in-line techniques for improving the automation and sample throughput are also discussed. The final part summarizes the success in the modification of original MSPD procedures.

Analysis of Dyes in Cosmetics: Challenges and Recent Developments

Colour plays a decisive role in the marketing of a cosmetic product. Among thousands of substances used to colour, synthetic dyes are the most widespread in the industry. Their potential secondary effects on human health and different regulatory requirements for their use between the main world markets make analytical control necessary to guarantee the safety of a cosmetic product. However, methodologies for the determination of dyes in cosmetics are scarce with respect to those reported for other cosmetic ingredients such as preservatives or ultraviolet UV filters. In addition, most of the existing methods just consider a part of the total of dyes regulated. On the other hand, many methods have been developed for matrices different than cosmetics such as foodstuff, beverages or wastewater. The current paper reviews the recent developments in analytical methodologies for the control of synthetic dyes in cosmetics proposed in the international scientific literature in the last 10 years (2008–2018). A trend towards the use of miniaturized extraction techniques is evidenced. Due to the hydrophilic nature of dyes, liquid chromatography is the most usual choice in combination with absorbance detectors and, more recently, with mass spectrometry.