Parabens

Parabens in Cosmetics

Shaundrea Rechsteiner, Business Development

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Parabens are widely used as preservatives in many cosmetic and personal care products for preventing growth of yeast and mold. Parabens are used in everything from shampoos and cosmetics to body lotions and sunscreens. The chemicals have generated increasing health concerns because they mimic estrogens, which have been linked, in some studies, to an increased risk of breast cancer and reproductive problems.

Methylparaben, propyl paraben, butylparaben and ethylparaben are the most common parabens used today.

The European Commission has amended Annex II of the EU Cosmetic Regulation, adding five parabens to the list of substances prohibited in cosmetic products. They are:

• isopropylparaben;
• isobutylparaben;
• phenylparaben;
• benzylparaben; and
• pentylparaben

Impact Analytical has experience with the quantitation and detection of parabens using:

• High Performance Liquid Chromatography (HPLC) for quantitation of parabens used as preservatives (with concentrations of approximately 0.1%) and
• Gas Chromatography – Mass Spectrometry (GC-MS) for detection of parabens at low part per million (ppm) levels. Note that detection limits may be matrix dependent.

Case Study 1 (Residual Parabens):
A customer provided a sample of a lotion (labeled paraben-free) for analysis of seven (7) specific parabens. The goal of the project was to confirm these specific parabens were not present in the sample. The customer provided the lotion product for analysis.

A standard mixture of seven parabens at 10 parts per million (ppm) each was purchased and analyzed using both LC/MS and GC/MS techniques. While both methods could separate and detect the individual parabens, GC/MS provided better separation and sensitivity (See Figure 1).

TIC 1

Figure 1. GC/MS separation and detection of standard of seven parabens at 10 ppm (w/v)

After identifying GC/MS as the method of choice, an aliquot of the sample was collected and spiked with the seven parabens at 10 ppm. The spiked lotion, the sample and a corresponding blank were extracted in methanol using a combination of ultrasonication and mechanical shaking. The resulting extracts were filtered and analyzed by GC/MS. There were no detectable parabens in the sample. Figure 2 shows the TIC chromatogram for the spiked lotion extract. The parabens are clearly recovered and capable of being detected in the spiked lotion using GC/MS. 

 

TIC 2

Figure 2.  GC/MS total ion chromatograms of paraben-free moisturizing lotion spiked with seven parabens at 10 ppm (w/v) 

1. Methyparaben
2. Ethylparaben
3. iso-Propylparaben
4. n-Propylparaben
5. iso-Butylparaben
6. n-Butylparaben
7. Benzylparaben

Case Study 2 (Preservative Analysis):
A customer provided a sample of a cream product for analysis of the concentration of parabens (propyl paraben and methyl paraben) used as a preservative. The goal of the project was to confirm the amount of propyl paraben and methyl paraben that was present in the sample. The customer provided the cream product and the propyl paraben and methyl paraben (to be used for preparation of reference standard solutions).

The propyl paraben and methyl paraben reference solutions and prepared sample solution were analyzed by Ultra-Performance Liquid Chromatography (UPLC) with ultraviolet detection (UV) using a Waters Acquity UPLC system.

Methyl paraben was detected at a concentration of 0.210% in the cream product, and propyl paraben was detected at 0.0968%. The calibration curves used to quantitate methyl and propyl paraben are located in Figures 1 and 2, respectively. Example chromatograms of an acetonitrile blank, methyl paraben standard, propyl paraben standard and cream sample are presented in Figures 3 through 6, respectively.

TIC 3
Figure 1:  Calibration curve used to quantitate methyl paraben in cream product