Rapid and simultaneous determination of hexapeptides (Ac-EEMQRR-amide and H2N-EEMQRR-amide) in anti-wrinkle cosmetics by hydrophilic interaction liquid chromatography–solid phase extraction preparation and hydrophilic interaction liquid chromatography wit

A rapid method for the simultaneous determination of Ac-EEMQRR-amide and H2N-EEMQRR-amide in cosmetic products was developed and evaluated. This analytical procedure involved extracting samples with 0.1:0.1:85:15 (v:v) trifluoroacetic acid (TFA):formic acid:acetonitrile (ACN):water and determination by hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC–MS/MS). Samples showing serious ion suppression were further cleaned up using HILIC–SPE prior to HILIC–MS/MS analysis. Stable isotopically labeled peptides, corresponding to the above two peptides, were used as internal standards to correct for loss of recovery and matrix effects. Electrospray ionization (ESI) in the positive mode was used. The linear range was 2.0–1000 ng/mL for Ac-EEMQRR-amide and 25.0–2500 ng/mL for H2N-EEMQRR-amide. Thirteen commercial products were analyzed for the two peptides using this method. The amounts of Ac-EEMQRR-amide in the samples ranged from none detected to 42.3 μg/g. H2N-EEMQRR-amide was not detected in any of the samples. The recoveries for Ac-EEMQRR-amide and H2N-EEMQRR-amide ranged from 85% to 110% and 84% to 119%, respectively, at the spiking level of 30 μg/g.