Determination of Laccaic Acids in Black Tea and Brown Sugar by Solid Phase Extraction-High Performance Liquid Chromatography
A new method was established for the determination of laccaic acids in black tea and brown sugar by solid phase extraction-high performance liquid chromatography(SPE-HPLC).The samples were ultrasonic extracted by water,then cleaned up by a polyamide(PA)SPE column.The chromatographic separation was achieved on an XB-C18 column(50×4.6 mm,3.0 μm)by linear gradient elution with methanol/ammonium acetate solution(containing 0.009%phosphoric acid)as the mobile phase.The results showed that there was a good linear correlation(r>0.999)between the peak area and concentration of laccaic acids in the range of 0.023-5.86 mg/L.The limits of quantification(LOQs)of laccaic acids were 0.025-0.047 mg/kg.The spiked recoveries for the samples and relative standard deviations(RSDs)were 96.2%-104.6%and 0.6%-4.0%,respectively.The separation of laccaid acids could be achieved within 7 minutes on common liquid chromatography instrument.It was sensitive and repeatable for the quantitative determination of laccaic acids in black tea and brown sugar with good anti-interference ability.
Black teaBrown sugarLaccaic acidSolid phase extractionHigh performance liquid chromatography(HPLC)