Margolis S A, Paule R C, Ziegler R G
Organic Analytical Chemistry Division, National Institute for Standards and Technology, Gaithersburg, MD 20899.
Clin Chem. 1990 Oct;36(10):1750-5.
We describe a rapid method for accurately and precisely measuring ascorbic acid and dehydroascorbic acid in plasma. Total analysis time is less than 10 min, replicate analyses of a single pool provide precision less than or equal to 2%, and values measured in supplemented samples agree with known concentrations of 4.68 and 11.83 mg/L. The stability and homogeneity of lyophilized plasma samples supplemented with ascorbic acid and dithiothreitol are documented. We also describe a procedure in which metaphosphoric acid (50 g/L) is used to prepare a reference material for the measurement of ascorbic acid and dehydroascorbic acid. The procedure for both acids consists of first measuring the native ascorbic acid, then reducing the dehydroascorbic acid, at neutral pH, with dithiothreitol, and finally measuring the total ascorbic acid; dehydroascorbic acid is then determined by difference. The metaphosphoric-acid-treated samples were stable at -70 degrees C, but stability decreased with temperature over the range examined, 4-50 degrees C.
我们描述了一种快速方法，用于准确且精确地测量血浆中的抗坏血酸和脱氢抗坏血酸。总分析时间少于10分钟，对单个混合样本进行重复分析的精密度小于或等于2%，在添加样本中测得的值与已知浓度4.68和11.83 mg/L相符。记录了添加抗坏血酸和二硫苏糖醇的冻干血浆样本的稳定性和均匀性。我们还描述了一种程序，其中使用偏磷酸（50 g/L）制备用于测量抗坏血酸和脱氢抗坏血酸的参考物质。两种酸的测量程序包括：首先测量天然抗坏血酸，然后在中性pH下用二硫苏糖醇将脱氢抗坏血酸还原，最后测量总抗坏血酸；然后通过差值确定脱氢抗坏血酸。经偏磷酸处理的样本在-70℃下稳定，但在所研究的4 - 50℃温度范围内，稳定性随温度降低。
