基于液相色谱的镇江香醋及其相关产品中四甲基吡嗪的分析方法

建立测定镇江香醋及其相关产品中四甲基吡嗪含量的超高效液相色谱（ultra-high performance liquid chromatography，UPLC）法和高效液相色谱（high performance liquid chromatography，HPLC）法。采用酸化乙醇溶液提取样品中的四甲基吡嗪，以25%甲醇溶液和75%的酸性溶液（1%乙酸和0.05%三氟乙酸溶液，pH 2.4）作为流动相，在UPLC法中采用填料粒径小的C18色谱柱（2.1 mm×100 mm，1.5 μm），在HPLC法中使用SB-C18色谱柱（4.6 mm×250 mm，5 μm），流速分别为0.3 mL/min和0.8 mL/min，检测波长为297 nm，标准曲线的线性范围均为0.50～50.00 μg/mL，测定结果的相对标准偏差均小于3%，平均回收率在87.9%以上。在UPLC法中四甲基吡嗪的保留时间为1.6 min，检出限为0.000 3 g/kg，定量限为0.001 g/kg，在HPLC法中四甲基吡嗪的保留时间为9.7 min，检出限为0.008 g/kg，定量限为0.025 g/kg。

Determination of Tetramethylpyrazine in Zhenjiang Balsamic Vinegar and Related Products by Ultra-high Performance Liquid Chromatography and High Performance Liquid Chromatography

In the present study, an ultra-high performance liquid chromatography (UPLC) method and a high performance liquid chromatography (HPLC) method were developed for the determination of tetramethylpyrazine in Zhenjiang balsamic vinegar and related products. Tetramethylpyrazine was extracted from samples with acidic ethanol aqueous solution. The mobile phase was a mixture of 25% methanol and 75% acidic aqueous solution (containing 1% acetic acid and 0.05% trifluoroacetic acid, pH 2.4). A C18 column with small packing particle size (2.1 mm × 100 mm, 1.5 μm) was used in UPLC while an SB-C18 column (4.6 mm × 250 mm, 5 μm) was used in HPLC. The flow rates of the columns were 0.3 and 0.8 mL/min, respectively, and the detection wavelength was set at 297 nm. The calibration curves obtained were linear over the range of 0.50–50.00 μg/mL. The mean absolute recoveries were at least 87.9% with relative standard deviations less than 3%. The retention time of tetramethylpyrazine was 1.6 min in the UPLC method compared to 9.7 min in HPLC. Moreover, the limits of detection (LODs) of the two methods were 0.000 3 and 0.008 g/kg, respectively, and the limits of quantitation (LOQs) were 0.001 and 0.025 g/kg, respectively.