CMC Analysis Laboratory, Toray Research Center, Inc., 9-1, Oe-Cho, Minato, Nagoya, Aichi, 455-8502, Japan.
Organic Analysis Laboratory, Toray Research Center, Inc., 3-2-11, Sonoyama, Otsu, Shiga, 520-8567, Japan.
Anal Sci. 2023 Sep;39(9):1591-1600. doi: 10.1007/s44211-023-00361-1. Epub 2023 Jun 6.
After extractive alkylation combined with plasma deproteinization, we used gas chromatography to assay for short-chain carboxylic acids from formic acid to valeric acid in plasma and urine. It was possible to provide highly sensitive analysis with 0.1-3.4 µg/mL as the limit of detection for plasma and 0.6-8.0 µg/mL for urine, with a correlation coefficient of 1.000 for the linear regression calibration curves. For plasma, deproteinization using ultrafiltration before extractive alkylation resulted in a higher sensitivity for acetic, propionic, butyric, and valeric acids compared with the method without deproteinization. The concentrations of formic acid and acetic acid were determined to be 6 µg/mL and 10 µg/mL, respectively, in the tested plasma, and 22 µg/mL and 32 µg/mL, respectively, in the tested urine. Concentrations from propionic acid to valeric acid were ≤ 1.3 µg/mL. In addition, high concentrations of sulfate, phosphate, hydrogen carbonate, ammonium, and/or sodium ions did not remarkably inhibit the derivatization of carboxylic acids, although hydrogen carbonate ions significantly inhibited that of formic acid.
经萃取烷基化结合血浆除蛋白后，我们采用气相色谱法测定了血浆和尿液中甲酸至戊酸的短链羧酸。对于血浆，检测限为 0.1-3.4μg/mL，尿液为 0.6-8.0μg/mL，相关系数为 1.000，实现了高灵敏度分析。与未经除蛋白的方法相比，萃取烷基化前采用超滤进行血浆除蛋白，可提高对乙酸、丙酸、丁酸和戊酸的灵敏度。检测血浆中甲酸和乙酸的浓度分别为 6μg/mL 和 10μg/mL，尿液中分别为 22μg/mL 和 32μg/mL。丙酸至戊酸的浓度均≤1.3μg/mL。此外，尽管碳酸氢根离子显著抑制了甲酸的衍生化，但高浓度的硫酸盐、磷酸盐、碳酸氢盐、铵根离子和/或钠离子并未显著抑制羧酸的衍生化。
