Determination of total phthalate in cosmetics using a simple three-phase sample preparation method

Area of Science:

• Analytical Chemistry
• Cosmetic Science

Background:

• Phthalates are common additives in cosmetics, raising health concerns.
• Accurate determination of phthalate content in cosmetic products is crucial for safety assessment.
• Existing methods often involve complex procedures and significant organic solvent use.

Purpose of the Study:

• To develop a simple, efficient, and environmentally friendly sample preparation method for phthalate determination in cosmetics.
• To validate the method using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS).

Main Methods:

• A novel three-phase extraction system (n-hexane, ethanol, aqueous alkali) was employed for sample hydrolysis and purification.
• An incremental purification strategy separated apolar ingredients, polar pigments, and phthalic acid.
• The method was optimized and validated for linearity, detection limits, quantification limits, recovery, and repeatability.

Main Results:

• Excellent linearity was achieved with correlation coefficients (r) of 0.998-0.999.
• Low limits of detection (5.1 μmol kg⁻¹) and quantification (9.2 μmol kg⁻¹) were obtained.
• High recoveries (84-97%) and good repeatability (RSDs ≤ 11%) were demonstrated across various cosmetic matrices without significant matrix effects.

Conclusions:

• The developed three-phase sample preparation method is simple, effective, and suitable for the accurate determination of total phthalates in diverse cosmetic products.
• This method offers a greener alternative by minimizing organic solvent consumption.
• The validated method was successfully applied to analyze 57 commercial cosmetic samples.