柑橘皮渣发酵-青贮饲料中有机酸的 RP-HPLC 测定

提出了一种利用反相高效液相色谱法同时测定柑橘皮渣发酵-青贮饲料中的6种有机酸的方法。水浴加热萃取法提取样品中的有机酸，采用Welch Materials XB-C18色谱柱（4.6 mm×250 mm,5 μm），检测波长为214 nm，流动相为0.05 mol/L磷酸二氢钾（pH 2.70）和甲醇（体积比为97：3），流速为0.80 mL/min，柱温为20 ℃，进样量为20 μL。在此条件下，6种有机酸在20 min内分离良好，各有机酸的回收率在94.96-103.43%，6种有机酸在各自线性范围内线性关系良好，相关系数均大于0.99，相对标准偏差都小于3%，最低检出限在0.53-2.51 mg/L范围。应用本方法测出的样品中草酸、甲酸、乳酸、乙酸、柠檬酸、丙酸含量分别为：0.84、3.69、51.13、20.61、1.76、1.06 mg/g。该方法具有样品处理简单、分析时间短、回收率好、精密度高、相对标准偏差低等优点，可用于柑橘皮渣发酵-青贮饲料中有机酸的检测。

Determination of Organic Acids in Fermentation-silage of Citrus Peel Wastes by RP-HPLC

Reversed phase high performance liquid chromatography （RP-HPLC） was used to detect six different organic acids from fermentation-silage of citrus peel wastes. The organic acids were extracted by heated water from samples and analyzed by RP-HPLC on an applied Welch Materials XB-C18 column （4.6 mm×250 mm, 5 μm） at 214 nm using the mixture of 0.05 mol/L monopotassium phosphate （pH 2.70） and methanol （97：3, V/V） as mobile phase at a flow rate of 0.80 mL/min. The injection load was 20μL and the column temperature was 20 ℃. Under these conditions, the six organic acids had a good separation within 20 minutes and the recovery rates ranged from 94.96 % to 103.43%. Each organic acid presented a good linear relationship between concentrations and chromatographic peak area with the correlation coefficient higher than 0.99 （R2 〉 0.99） and relative standard deviation less than 3% （RSD 〈 3%）. The lowest detection limit was between 0.53 to 2.51 mg/L. Consequently, the determined concentrations of six organic acids （oxalic acid, formic acid, lactic acid, acetic acid, citric acid and propionic acid） were 0.84, 3.69, 51.13, 20.61, 1.76 and 1.06 mg/g respectively. In conclusion, RP-HPLC was a convenient, rapid and accurate method for analysis of organic acids in fermentation-silage of citrus peel wastes.