Synthetic colourants in capsule dietary supplements on the Korean market

ABSTRACT

This study developed a rapid and easy analytical method for the simultaneous determination of nine synthetic colourants (SCs) in capsule dietary supplements. Sample pretreatment involved thermal treatment to dissolve gelatin, using the enzymes protease and amylase to prevent the gelation of gelatin and fat-soluble substances removal using petroleum ether. The method was linear (r² ≥0.999), with LOD of 0.009–0.029 μg/mL and LOQ of 0.42–1.40 μg/g. Recovery ranged from 90.9 to 108.9%. The relative expanded measurement uncertainty ranged from 4.1 to 6.3%. Allura Red AC (R40) and Brilliant Blue FCF (B1) were commonly detected in 20 of the 28 samples. Up to six SCs such as Tartrazine (Y4), Sunset yellow (Y5), Amaranth (R2), Erythrosine B (R3), R40 and B1 were detected in a single sample, ranging from 30.5 to 40.2 μg/g. Total content of SCs in various capsule supplements ranged from 0.3 to 73.7 μg/g.

KEYWORDS:

• Capsule dietary supplement
• enzyme
• simultaneous determination
• synthetic colourant
• thermal treatment

Disclosure statement

No potential conflict of interest was reported by the authors.

Author contributions

D. Lee: Formal analysis, Investigation, Methodology; S. Lee: Formal analysis; K.-G. Lee: Supervision; Validation; Investigation; Project administration.

Additional information

Funding

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea [grant number NRF, 2021R1A2B5B01002296].