胶束电动毛细管色谱法测定牛奶中脱氢乙酸

Determination of dehydroacetic acid in milk by micellar electrokinetic chromatography

目的建立快速、准确测定牛奶中脱氢乙酸含量的胶束电动毛细管色谱法。方法以内径50μm、总长度为30.2 cm(有效长度:20 cm)未涂层熔融石英毛细管为分离柱,以15 mmol/L硼砂+60 mmol/L H_3BO_3+100 mmol/L十二烷基硫酸钠为分离缓冲溶液;分离电压:13 k V;进样压力及时间:0.5 psi、4 s;操作温度25℃;检测波长:228 nm。结果脱氢乙酸质量浓度在1.5~200 mg/L内线性良好,线性相关系数r为0.999 9,检出限和定量限分别为0.5 mg/L(S/N=3)和1.5 mg/L(S/N=10)。平均回收率在95.2%~98.6%之间,相应相对标准偏差(RSD)在2.6%~3.4%之间。结论该法准确度高、前处理简单、试剂消耗少,非常适合于牛奶中脱氢乙酸的常规检测。

Objective A micellar electrokinetic chromatographic method was established to determine dehydroacetic acid in milk samples. Methods An uncoated fused-silica capillary with 50 μm i. d. and 30. 2 cm total length（ effective length： 20 cm） was used for separation. A solution of 15 mmol/L Borax,60 mmol/L boric acid and 100 mmol/L sodium dodecyl sulfate were used as the separation buffer. The separation voltage was 13 k V. The injection pressure and time was 0. 5 psi and 4 s,respectively. The operating temperature was 25 ℃ and the detection wavelength was 228 nm. Results The method showed good linearity and reproducibility in the ranges of 1. 5-200 mg/L and the correlation coefficients（ r） were 0. 999 9. The limit of detection（ LOD,S/N = 3） and limit of quantitation（ LOQ,S/N = 10） were 0. 5 mg/L and 1. 5 mg/L,respectively. The average recoveries were between 95. 2 % and 98. 6 % with relative standard deviations（ RSDs） ranging from 2. 6 % to 3. 4 %. Conclusion The method with good accuracy,simple sample pretreatment steps and low reagent consumption,is very suitable for the routine analysis of dehydroacetic acid in milk samples.