Centro de Química da Madeira (CQM), Centro de Ciências Exactas e da Engenharia da Universidade da Madeira, Funchal, Portugal.
Anal Bioanal Chem. 2012 May;403(4):1049-58. doi: 10.1007/s00216-011-5668-x. Epub 2012 Jan 6.
This study provides a versatile validated method to determine the total vitamin C content, as the sum of the contents of L-ascorbic acid (L-AA) and dehydroascorbic acid (DHAA), in several fruits and vegetables and its degradability with storage time. Seven horticultural crops from two different origins were analyzed using an ultra-high-performance liquid chromatographic-photodiode array (UHPLC-PDA) system, equipped with a new trifunctional high strength silica (100% silica particle) analytical column (100 mm × 2.1 mm, 1.7 μm particle size) using 0.1% (v/v) formic acid as mobile phase, in isocratic mode. This new stationary phase, specially designed for polar compounds, overcomes the problems normally encountered in HPLC and is suitable for the analysis of large batches of samples without L-AA degradation. In addition, it proves to be an excellent alternative to conventional C18 columns for the determination of L-AA in fruits and vegetables. The method was fully validated in terms of linearity, detection (LOD) and quantification (LOQ) limits, accuracy, and inter/intra-day precision. Validation experiments revealed very good recovery rate of 96.6 ± 4.4% for L-AA and 103.1 ± 4.8 % for total vitamin C, good linearity with r(2)-values >0.999 within the established concentration range, excellent repeatability (0.5%), and reproducibility (1.6%) values. The LOD of the method was 22 ng/mL whereas the LOQ was 67 ng/mL. It was possible to demonstrate that L-AA and DHAA concentrations in the different horticulture products varied oppositely with time of storage not always affecting the total amount of vitamin C during shelf-life. Locally produced fruits have higher concentrations of vitamin C, compared with imported ones, but vegetables showed the opposite trend. Moreover, this UHPLC-PDA methodology proves to be an improved, simple, and fast approach for determining the total content of vitamin C in various food commodities, with high sensitivity, selectivity, and resolving power within 3 min of run analysis.
本研究提供了一种通用的、经过验证的方法，用于确定几种水果和蔬菜中的总维生素 C 含量，即 L-抗坏血酸（L-AA）和脱氢抗坏血酸（DHAA）的含量之和，以及其随储存时间的降解情况。使用配备新的三功能高强度硅胶（100%硅胶颗粒）分析柱（100mm×2.1mm，1.7μm粒径）的超高效液相色谱-光电二极管阵列（UHPLC-PDA）系统，对来自两个不同来源的 7 种园艺作物进行了分析，流动相为 0.1%（v/v）甲酸，采用等度模式。这种新的固定相专门设计用于分析极性化合物，克服了 HPLC 中通常遇到的问题，适用于在不发生 L-AA 降解的情况下分析大量样品。此外，它被证明是用于测定水果和蔬菜中 L-AA 的常规 C18 柱的绝佳替代品。该方法在线性、检测（LOD）和定量（LOQ）限、准确度和日内/日间精密度方面进行了全面验证。验证实验表明，L-AA 的回收率为 96.6±4.4%，总维生素 C 的回收率为 103.1±4.8%，在建立的浓度范围内，线性度良好，r(2)-值>0.999，重复性好（0.5%），重现性（1.6%）。该方法的 LOD 为 22ng/mL，LOQ 为 67ng/mL。可以证明，不同园艺产品中的 L-AA 和 DHAA 浓度随储存时间的变化呈相反趋势，并不总是影响货架期内总维生素 C 的含量。与进口产品相比，本地生产的水果具有更高的维生素 C 浓度，但蔬菜则呈现相反的趋势。此外，这种 UHPLC-PDA 方法被证明是一种改进的、简单的、快速的方法，可用于测定各种食品中维生素 C 的总含量，具有高灵敏度、选择性和分辨率，在 3 分钟的运行分析时间内即可完成。
