Accurate Determination of Acrylamide Residues in Cosmetic Hydrogels by High-Performance Liquid Chromatography

Polyacrylamide is commonly used in shampoos, shower gels, and face creams to adjust texture, or as an auxiliary ingredient in styling products, due to its excellent thickening, stabilizing, and film-forming properties. However, if the polymerization reaction is incomplete during the production process, trace amounts of acrylamide monomer may remain. Although the residual levels in cosmetics are typically well below the established safety thresholds, concerns persist regarding its potential skin irritation and neurotoxicity (with long-term high-dose exposure). In recent years, with growing consumer attention to ingredient safety, regulatory agencies in various countries have established limits for acrylamide residues in cosmetics. For example, the European Union requires that the monomer residue in polyacrylamide ingredients ≤ 0.1%. Companies have also been optimizing production processes to mitigate associated risks. For ordinary consumers, there is no need for alarm when using compliant products in daily life. However, understanding the presence of this "hidden ingredient" can help us read ingredient lists more rationally and approach product selection with greater confidence. After all, safety always comes first as the foundation of beauty.

This experiment referenced the national standard "GB/T 29659-2013 Determination of Acrylamide in Cosmetics" and was conducted using a Wayeal High-Performance Liquid Chromatograph LC3400 series, equipped with an ultraviolet detector.

Keywords: Cosmetics; Acrylamide; High-Performance Liquid Chromatography.

1. Instruments and Reagents

1.1 HPLC Configuration List

Table 1 Instrument Configuration List

1.2 Reagents and Standards

Table 2 Table of Reagents and Standards

1.3 Experiment Materials and Auxiliary Equipment

Analytical balance

Ultrasonic cleaner

Vortex mixer

2. Experiment Method

2.1 Reagents Preparation

2.1.1 Acrylamide standard working solutions: Precisely transfer 1.0mL of acrylamide reference standard into a 10mL volumetric flask. Add an appropriate amount of water to dissolve and dilute to the mark, then mix well to obtain the standard stock solution (100mg/L). Sequentially and precisely transfer appropriate volumes of the stock solution into separate volumetric flasks, dilute with water to the mark, and mix well to prepare standard working solutions at concentrations of 0.1mg/L, 0.5mg/L, 1.0mg/L, 2.0mg/L, and 5.0mg/L.

2.1.2 Sample preparation: Precisely weigh 1g of polyacrylamide hydrogel and transfer it into a 50mL centrifuge tube. Add 20mL of water-methanol mixture (95:5, v/v) to dissolve. Sonicate the mixture for 10 minutes for extraction. Centrifuge at 6000 r/min for 10 minutes. Filter the supernatant through a 0.22μm micropore membrane. Transfer 1mL of the filtrate into a 10mL volumetric flask, and dilute to the mark with the water-methanol mixture (95:5, v/v) to obtain the sample solution.

3. Experiment Result

3.1 Precision Test

Fig 1 Overlap Chromatograms for the Standard (0.2mg/L)

Table 3 Standard(0.2mg/L) Test Data

The precision test showed that after six consecutive injections of the 0.2mg/L acrylamide standard working solution, the relative standard deviation (RSD) for retention time repeatability was 0.019%, and the RSD for peak area repeatability was 0.386%, indicating good precision.

3.2 Linear Test

Fig 2 Standard Curve Test Chromatogram

The linearity test demonstrated that within the range of 0.1–5.0 mg/L, the standard curve exhibited a linear correlation coefficient of 0.99999, indicating excellent linearity.

3.3 Sample Test

Fig 3 Sample Test Chromatogram

Sample testing revealed the presence of acrylamide in the tested gel, with a mean detected amount of 0.231mg/L. Calculated using the external standard method, the acrylamide content in the gel was determined to be 41.62ppm.

4. Conclusion

This experiment referenced the national standard "GB/T 29659-2013 Determination of Acrylamide in Cosmetics" and was conducted using a Wayeal High-Performance Liquid Chromatograph LC3400 series, equipped with an ultraviolet detector. The experimental results demonstrated excellent precision: for six consecutive injections of a 0.2mg/L acrylamide standard solution, the relative standard deviation (RSD) of retention time was 0.019%, and the RSD of peak area was 0.386%. Within the range of 0.1 to 5.0mg/L, the linear correlation coefficient was greater than 0.99999, indicating excellent linearity. For six consecutive analyses of the sample solution, the relative standard deviation (RSD) of retention time was 0.077%, and the RSD of peak area was 0.342%, showing good repeatability. The determined acrylamide content in the sample was 41.62ppm. All data obtained meet the instrumental requirements specified in the standard method.