Determination of residual 1,4‐dioxane in surfactants and cleaning agents using headspace single‐drop microextraction followed by gas chromatography–flame ionization detection

Validation and Collaborative Studies of Headspace Gas Chromatography-Mass Spectrometry for Determination of 1,4-Dioxane in Cosmetic Samples

BACKGROUND

1,4-Dioxane (1,4-D) is a byproduct of the synthesis of surfactants, typically found in some cosmetics products such as shampoo, toothpaste, and soap. The presence of 1,4-D in cosmetics products is limited to a certain amount since 1,4-D is classified as a probable human carcinogen.

OBJECTIVE

This present study was intended to validate static headspace gas chromatography-mass spectrometry (HS GC-MS) for the determination of 1,4-D in cosmetics products.

METHODS

The condition of HS and GC-MS was optimized to get the best condition for analysis of 1,4-D using 1,4-dioxane-d8 (1,4-D-d8) as internal standard (IS). The developed method was validated by evaluating the key performance characteristics, including specificity, linearity, limit of detection (LoD), limit of quantification (LoQ), accuracy, and precision.

RESULTS

The results showed that HS GC-MS was specific since the peaks of the selected ion monitoring (SIM) mode could be separated and confirmed at m/z 88 and m/z 96 for 1,4-D and 1,4-D-d8, respectively. The method was linear over the concentration range of 0.1287-1.2875 µg/mL, with R2 > 0.999 and RSD residuals <2.0. A collaborative study was conducted on this method, with 10 participating laboratories from four countries. The outcome of this study was found to be accurate and precise, as evidenced by the excellent recoveries ranging from 94.6% to 102.1%, and with good reproducibility with RSD values ranging from 0.2 to 1.1%. The collaborative studies exhibited that all data reported by 10 participating laboratories in four countries were inliers without any extreme values observed either in mean or RSD values.

CONCLUSIONS

HS GC-MS is found to be fit and suitable for the determination of trace level of 1,4-D in cosmetics products.

HIGHLIGHTS

The HS GC-MS method could be proposed as a standard method for quantitative analysis of 1,4-D in cosmetics products since the collaborative studies indicated that the developed method meet the requirement in "Guidelines for Collaborative Study Procedures to Validate Characteristics of a Method of Analysis."

Inhaled JAK Inhibitor GDC-0214 Nanoaggregate Powder Exhibits Improved Pharmacokinetic Profile in Rats Compared to the Micronized Form: Benefits of Thin Film Freezing

Asthma is a common chronic disease affecting the airways in the lungs. The receptors of allergic cytokines, including interleukin (IL)-4, IL-5, and IL-13, trigger the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway, which involves the pathogenesis of asthma. GDC-0214 is a JAK inhibitor that was developed as a potent and selective target for the treatment of asthma, specifically targeting the lungs. While inhaled GDC-0214 is a promising novel treatment option against asthma, improvement is still needed to achieve increased potency of the powder formulation and a reduced number of capsules containing powder to be inhaled. In this study, high-potency amorphous powder formulations containing GDC-0214 nanoaggregates for dry powder inhalation were developed using particle engineering technology, thin film freezing (TFF). A high dose per capsule was successfully achieved by enhancing the solubility of GDC-0214 and powder conditioning. Lactose and/or leucine as excipients exhibited optimum stability and aerosolization of GDC-0214 nanoaggregates, and aerosolization of the dose was independent of air flow through the device between 2 and 6 kPa pressure drops. In the rat PK study, formulation F20, which contains 80% GDC-0214 and 20% lactose, resulted in the highest AUC0-24h in the lungs with the lowest AUC0-24h in the plasma that corresponds to a 4.8-fold higher ratio of the lung-to-plasma exposures compared to micronized crystalline GDC-0214 powder administered by dry powder inhalation. Therefore, GDC-0214 nanoaggregates produced by TFF provided an improved dry powder for inhalation that can lead to enhanced therapeutic efficacy with a lower risk of systemic toxicity.

Solvent extraction and gas chromatography-mass spectrometric determination of probable carcinogen 1,4-dioxane in cosmetic products

In the present work, a method based on solvent extraction and gas chromatography-mass spectrometry (GC-MS) has been validated for the determination of 1,4-dioxane in cosmetics. Various solvents including ethyl acetate, hexane, methanol, dichloromethane and acetone have been used for the extraction of 1,4-dioxane, among them the ethyl acetate was found to be the most efficient extracting solvent. This method has offered excellent quality parameters for instance linearity (R² > 0.9991), limit of detection (LOD, 0.00065-0.00091 µg/mL), limit of quantification (LOQ, 0.00217-0.00304 µg/mL) and, precision intra-day (1.65-2.60%, n = 5) and inter-day (0.16-0.32%, n = 5) in terms of relative standard deviation (RSD%). A total of thirty-nine cosmetic samples of different brands and origin have been studied. Among them, the 1,4-dioxane was found in twenty-three samples (FB₁-FB₇, MC₁-MC₄, MC₆-MC₈, HS₃, HS₅, BL₁-BL₃, BL₅ and PLD₁-PLD₃) at the levels between 0.15 µg/mL and 9.92 µg/mL, whereas in sixteen samples (MC₅, HS₁, HS₂, SG₁-SG₅, BL₄ and HP₁- HP₆) was found to be not detected. The recovery values were achieved between 93% and 99% in both low and high level of spiked samples. In comparison to the traditional analytical techniques, the proposed method was found to be very sensitive and cost-effective for the routine analysis of 1,4-dioxane at low concentration in cosmetics.

The determination of 1,4-dioxane in cosmetic products by gas chromatography with tandem mass spectrometry

1,4-dioxane is a potential human carcinogen and contaminant produced during the manufacturing process from specific cosmetic ingredients, such as certain detergents and emulsifiers. As such, 1,4-dioxane is not identified on product ingredient labels. To assess the concentration of 1,4-dioxane in cosmetic products, a gas chromatography-tandem mass spectrometry (GC-MS/MS) method using pulsed split injection and electron ionization was developed and validated. For liquid cosmetic products such as shampoo and lotion, test portions were extracted using fast ultrasound-assisted extraction (UAE) procedure without sample cleanup. For solid products (e.g. beauty bars), a C₁₈ solid phase extraction (SPE) procedure was optimized to reduce potential interferences. The corresponding stable isotopically labeled analogue (1,4-dioxane-d₈) was selected as an internal standard to compensate for matrix effects and sample recovery. Method recovery experiments were performed in lotion, oil gel, hair detangler, bubble bath and beauty bar (solid) sample matrices with recoveries of 84-108% and relative standard deviations less than 5% at three spike concentrations. Method limits of detection (LOD) and quantification (LOQ) for 1,4-dioxane were determined at 0.2 μg/g and 0.5 μg/g, respectively. The method was successfully used to determine 1,4-dioxane in 82 leave-on and rinse-off cosmetic products marketed toward children including bath products, hair treatment, lotions, beauty bars, washes, shampoos, and other products. 1,4-dioxane was detected in 47 of the 82 products with an average concentration of 1.54 μg/g (range: 0.23-15.3 μg/g). The method can increase sample throughput and reduce matrix-induced interferences.

Current direction and advances in analytical sample extraction techniques for drugs with special emphasis on bioanalysis

Analytical techniques may not be compatible or sufficiently sensitive to the analytes, unless it undergoes a specific sample extraction procedure. Sample extraction can be considered as one of the key steps in analysis. Analysis of a poorly treated sample may produce inferior quality of analytical data. Continuous advancement and development of newer sample extraction techniques such as solid phase microextraction, ultrasound, magnetically and microwave assisted magnetic extraction; electro-membrane extraction and dried blood spotting are to address the shortcomings of the existing techniques and to provide more automation, minimizing preparation time and make them high throughput. This review summarizes the suitability of application of the advanced sample preparation techniques available for chemical and bioanalysis in a comprehensive manner. This review also provides a scientific guidance for selecting the appropriate sample extraction technique based on sample type.