Abstract:

A method for the simultaneous determination of 22 acidic dyes (acid yellow 23, acid red 18, acid blue 7, etc) in edible packagings was developed using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The samples were extracted with acetonitrile-methanol (5:5, v/v), and then cleaned up with Strata-X-AW solid-phase extractor. The analytes were separated on a Zorbax Eclipse Plus C₁₈ column (100 mm×3.0 mm, 1.8 μm) by gradient elution with acetonitrile-10 mmol/L ammonium acetate as the mobile phases. The 22 acidic dyes were determined by electrospray negative ion source (ESI^-), and multiple reaction monitoring (MRM) mode. The qualitative analysis was based on the retention times and characteristic ion pairs consisting of one parent ion and two fragment ions, and the quantitative analysis was carried out by matrix-matched external standard method. The results showed that the calibration curves had good linearity for the 22 acidic dyes, and the correlation coefficients (r²) were larger than 0.991. The limits of quantitation (LOQs, S/N≥10) were in the range of 0.1-2.0 mg/kg in three different matrices (plant capsule, gelatine capsule, oblatum). The average recoveries were in the range of 78.4%-109.5% for the 22 acidic dyes with the relative standard deviations (RSDs) from 4.6% to 14.5% at three spiked levels (1×LOQ, 2×LOQ and 10×LOQ). This method is suitable for the determination of acidic dyes in edible packagings with the characteristics of high accuracy and precision.

Key words: acidic dyes, edible packagings, high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), solid-phase extraction (SPE)