Abstract:

A high performance liquid chromatography with diode array detection (HPLC-DAD) method for determining
the synthetic pigments tartrazine, amaranth, carmine, temptation, sunset yellow and bright blue in Chinese steamed bread
of coarse grains with simple pretreatment, high sensitivity and good repeatability was proposed in this study. Samples of
steamed bread were extracted with a mixture solvent composed of absolute ethanol, ammonia water and pure water (7:2:1,
V/V) and the extracts were separated on a Waters Symmetry® C18 column (250 mm × 4.6 mm, 5 μm) at a flow rate of
1.0 mL/min. The column temperature was set at 35 ℃. HPLC chromatograms were detected at 425, 483, 520 and 620 nm,
respectively. Mobile phase A was methanol and mobile phase B consisted of 0.02 mol/L ammonium acetate, 1% acetic
acid and 0.2% triethylamine in water (pH 4). A gradient elution program was used. Baseline separation was achieved for
all six kinds of synthetic pigments, providing a good linear relationship (r = 0.999 9). The recoveries from spiked samples
for tartrazine, amaranth, carmine, temptation, sunset yellow and bright blue were, respectively, 97.94%, 96.40%, 96.28%,
97.63%, 98.80% and 100.40% with RSD less than 2.0%. This method is useful to discriminate undyed from dyed steamed
breads of coarse grains.

Key words: high performance liquid chromatographic with diode array detection (HPLC-DAD), Chinese steamed bread, synthetic pigments, detection