ULTRASOUND-ASSISTED EMULSIFICATION MICROEXTRACTION OF VARIOUS PRESERVATIVES FROM COSMETICS, BEVERAGES, AND WATER SAMPLES

Determination of D&C Red 33 and Patent Blue V Azo dyes using an impressive electrochemical sensor based on carbon paste electrode modified with ZIF-8/g-C3N4/Co and ionic liquid in mouthwash and toothpaste as real samples

Synthetic azo dyes are widely used in a variety of industries, but many of them pose a risk to human health, particularly when consumed in large quantities. As a result, their existence in products should be closely monitored. D&C red 33 and Patent Blue V are mostly used in cosmetics, especially in toothpaste and mouthwashes. A novel carbon paste electrode modified with ZIF-8/g-C3N4/Co nanocomposite and 1-methyl-3-butylimidazolium bromide as an ionic liquid was employed as a highly sensitive reproducible electrochemical sensor for the simultaneous determination of these common dyes. ZIF structure has unique properties such as high surface area, suitable conductivity, and excellent porosity. The electrochemical behavior of the suggested electrode was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). To characterize the synthesized nanocomposites, scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were applied to investigate the structure of nanocomposites. Under the optimized conditions, the modified sensor offered a wide linear concentration range 0.08-10 μM (R2 = 0.9906) and 10-900 μM (R2 = 0.9932) with a low limit of detection of 0.034 μM. The value of diffusion coefficient (D), and the electron transfer coefficient (α) was calculated to be 310 × 10-5, and 0.9 respectively. This technique offered a successful performance for the determination of target analyte in the real samples with acceptable results between 96% and 107%.

Ultrasound-assisted cloud point microextraction of certain preservatives in real samples and determination by HPLC

Ultrasound-assisted cloud point microextraction (UA-CPME) was performed for certain preservatives (p-hydroxy benzoic acid and its alkyl esters, methyl, ethyl, propyl and butyl parabens). Then, an HPLC method was developed for their simultaneous determination in pharmaceutical and cosmetic samples. The chromatograms of these substances were recorded on a C18 column using a gradient elution technique with various solvent systems at different flow rates and at 254 nm wavelength using a diode-array detector (DAD). The analysis conditions found by the classical method were optimized using the Box-Behnken design (BBD). In the design, the effect of each factor was examined with 3 and 4 factors for UA-CPME and HPLC analyses, respectively. The brij 58 concentration (BC), Na₂SO₄ amount (SA) and extraction time (ET) for UA-CPME, and the mobile phase 1 (MP1) ratio, mobile phase 2 (MP2) ratio, flow rate (FR) and column temperature parameters for HPLC analysis were obtained for the investigated levels. The factors affecting the resolution were determined by applying regression analysis to the experimental results. The analysis of variance (ANOVA) test was applied to ensure result reliability. The ANOVA test was used to determine the reliability of the results. A model was created with the obtained data. The developed method was validated by examining linearity, reproducibility, accuracy, limit of quantification and limit of the detection. Methyl paraben (with 0.148% RSD value and 0.060% relative error), and propyl paraben (with 0.149% RSD value and 0.120% relative error) were determined in the syrup sample by the developed method. Methyl paraben with recovery values of (98.32-99.42)% and ethyl paraben with recovery values of (99.17-99.41)%, were determined in a hand cream.

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.

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.

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

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

A Novel HPLC Method for Simultaneous Determination of Methyl, Ethyl, n-propyl, Isopropyl, n-butyl, Isobutyl and Benzyl Paraben in Pharmaceuticals and Cosmetics

INTRODUCTION

The alkyl esters of p-hydroxybenzoic acid at the C-4 position, "the parabens," including methyl, ethyl, propyl, and butyl, are widely used as antimicrobial preservatives in foods, cosmetics, and pharmaceuticals. Official regulations on the use of these compounds make their analysis essential for the estimation of their exposure.

METHODS

On this basis, the presented study was realized to develop a simple, selective and cheap high-performance liquid chromatographic method for the quantitative determination of methylparaben, ethylparaben (EP), n-propyl paraben (NPP), isopropyl paraben (IPP), n-butyl paraben (NBP), isobutyl paraben (IBP) and benzyl paraben (BP) in pharmaceuticals and cosmetic products.

RESULTS

The chromatographic separation of the analytes was achieved under flow rate gradient elution conditions using a C18-bonded core-shell silica particle column (2.6 μm particle size, 150 × 3.0 mm from Phenomenex Co.). The samples were injected into the system as aliquots of 1.0 μL, and the compounds were detected by using a photodiode array detector set at 254 nm wavelength. With this technique, seven paraben derivatives can be determined in the concentration range of 250-2000 ng/mL. The recovery of the method is in the range of 99.95-13.84%, and the RSD is at a maximum value of 3.95%.

CONCLUSION

The proposed method was fully validated and successfully applied to different pharmaceutical and cosmetic samples (n=16), including syrups, suspensions, oral sprays, gels, etc. At least one paraben derivative was detected in six samples and was determined quantitatively. The maximum amount of a paraben derivative found in the analyzed samples was 321.7 ng/mL, which was MP. To the best of our knowledge, this is the first LC method, which is applicable both on pharmaceutical and cosmetic samples.

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

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