Gas Chromatography-Mass Spectrometry (GC-MS) was Used for The Determination of Cyclic Volatile Dimethylsiloxane (D4) in Personal Care Products

Abstract

Background and Aims: Compounds of low-molecular-weight cyclic volatile dimethylsiloxane (cVMS) are widely used in per sonal care products due to their beneficial properties for consumer goods. However, the European Chemicals Agency (ECHA) has proposed restrictions on two cyclic siloxanes, octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5), in rinse-off Personal care products that are rinsed off and discharged into drains. The main concerns with D4 and D5 are their persistence and accumulation in the water bodies. The goal of this restriction is to reduce their discharge into surface waters. According to the ECHA, these substances should not be sold or used in concentrations of 0.1% or more by weight in rinse-off personal care products. Analysing cyclic siloxanes in these products is vital for understanding human exposure to these substances. ECHA mandates dependable analytical methods for manufacturers and government agencies to verify adherence to the restrictions. A simple, fast, and easily applicable extraction method using gas chromatography mass spectrometry (GC-MS) for the precise measurement of D4 at around 0.1% by weight of the total formulation in personal care products (PCPs) is proposed in this article. Methods: Detection was performed using a GC-MS instrument equipped with an electron impact (EI) ion source and operated using the selected ion monitoring (SIM) mode. The mass-to-charge ratios (m/z) monitored for D4 were 281.0, 282.0, and 283.0. The monitored mass-to-charge ratios (m/z) for D4 were 281.0, 282.0, and 283.0. Results: The proposed method showed excellent linearity, with a coefficient of determination (r²) exceeding 0.999. The limit of detection (LOD) and limit of quantification (LOQ) were 0.2320 μg/mL and 0.7735 μg/mL, respectively. The precision and accuracy of D4 were evaluated at concentrations of 3.0 µg/mL, 15.0 µg/mL, and 25.0 µg/mL. The coefficients of variation (CV) were 5.07%, 7.24%, and 4.95%, respectively, while the accuracy values were 103.17±0.16, 100.44±1.09, and 101.13±0.07, respectively, for these concentrations. These values are within the acceptable limit of ±15%. The results show that this GC MS method meets the regulatory standards and demonstrates satisfactory accuracy and precision. Real samples, such as beard oil and hair conditioner, were successfully analysed using this method. Conclusion: The developed GC-MS method provides a simple, accurate, and sensitive approach for detecting D4 in rinse-off personal care products. It meets regulatory requirements and is suitable for routine analysis, supporting efforts to control environmental exposure to cyclic siloxanes.

Keywords

• Gas Chromatography
• Octamethylcyclotetrasiloxane (D4)
• Personal Care Products
• Analytical Method Validation

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