在线固相萃取-二维液相色谱法同时测定儿童配方奶粉中维生素A、D、E

建立在线固相萃取(SPE)-二维液相色谱法同时测定儿童配方奶粉中脂溶性维生素A、D₂、D₃和α-、β-、γ-、δ-维生素E含量的方法。样品经皂化后直接进样,以聚合物为填料的PLRP-S色谱柱为在线固相萃取柱净化皂化液,采用SPE泵反向洗脱目标组分,并通过引入在线稀释将目标组分聚焦在第一维色谱柱柱头。以NuovaSil^TM PFP(4.6 mm×150 mm,3μm)为第一维色谱柱,甲醇-0.1%甲酸水溶液为流动相进行梯度洗脱,分离维生素A和E的4种异构体。以ChromCore PAH(4.6 mm×150 mm,3μm)为第二维色谱柱,甲醇-乙腈(90:10,v/v)为流动相,分离维生素D₂和D₃。结果表明,维生素A在5.0～500.0 ng/mL、维生素D在1.0～100.0 ng/mL、维生素E在50.0～5000.0 ng/mL线性范围内线性良好,相关系数均大于0.9999。维生素A、D₂、D₃和α-、β-、γ-、δ-维生素E的...

Simultaneous Determination of Vitamins A,D and E in Children's Formula Milk Powder by Combining Online Solid Phase Extraction and Two-Dimensional Liquid Chromatography

A method was developed for the simultaneous determination of fat-soluble vitamins A, D₂, D₃ and α-, β-, γ-, δ-vitamin E in children's formula milk powder by combining online solid phase extraction (SPE) and two-dimensional liquid chromatography. The saponified samples were directly injected into the constructed system and purified by using the polymeric-based PLRP-S column as the SPE column. Then the target analytes were eluted in back-flush mode from the SPE column by SPE pump and refocused on the head of the first-dimensional column by using online dilution. Vitamins A and four E homologues were separated on a NuovaSilTM PFP column (4.6 mm×150 mm, 3 μm) as the first-dimensional column using a mobile phase consisting of methanol and 0.1% formic acid in water by gradient elution, and vitamins D₂ and D₃ were separated on a ChromCore PAH column (4.6 mm×150 mm, 3 μm) as the second-dimensional column using a mobile phase consisting of methanol and acetonitrile (90:10, v/v). The results showed good linearity in the range of 5.0~500.0 ng/mL for vitamin A, 1.0~100.0 ng/mL for vitamin D and 50.0~5000.0 ng/mL for vitamin E, and the correlation coefficients were all better than 0.9999. The limits of quantification for vitamins A, D₂, D₃ and α-, β-, γ-, δ-vitamins E were 5.11, 1.22, 1.25, 83.82, 57.27, 56.61, 54.82 μg/100 g, respectively. The spiked recoveries were 91.20%~104.47%, and the relative standard deviations were 0.94%~3.34%. The results show that the method established in this paper has the advantages of simple pretreatment, high automation, high analytical efficiency, high accuracy and good reproducibility, and is suitable for the determination of vitamins A, D and E in children's formula milk powder.