Chen H M, Lifschitz C H
USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030.
Clin Chem. 1989 Jan;35(1):74-6.
We describe a procedure for preparing fecal samples for determination of volatile fatty acids (VFAs) by gas-liquid chromatography (GLC) and "high-performance" liquid chromatography (HPLC). The simple, one-step procedure involves only ultrafiltration through a membrane with a molecular-mass cutoff of 3000 Da. As revealed by the GLC chromatograms, ultrafiltration appears to be as effective as steam distillation in sample clean-up. It also enables higher, more reproducible analytical recoveries of long-chain VFAs. The VFA content of the filtrate can also be measured by HPLC. Use of the ion-exclusion mechanism completely resolves isobutyric acid and butyric acid on a cation-exchange column. The mean (+/- SD) percentage distribution values of VFAs (measured by GLC) from five healthy subjects were 56.0 +/- 3.5 (acetic acid), 17.0 +/- 5.3 (propionic acid), 2.9 +/- 1.5 (isobutyric acid), 18.8 +/- 5.8 (butyric acid), 2.3 +/- 1.2 (isovaleric acid), and 2.9 +/- 0.8 (valeric acid).
我们描述了一种通过气液色谱法（GLC）和“高效”液相色谱法（HPLC）制备粪便样本以测定挥发性脂肪酸（VFA）的方法。这个简单的一步程序仅涉及通过截留分子量为3000 Da的膜进行超滤。从GLC色谱图可以看出，超滤在样品净化方面似乎与蒸汽蒸馏一样有效。它还能实现更高、更可重复的长链VFA分析回收率。滤液中的VFA含量也可以通过HPLC进行测量。利用离子排斥机制可在阳离子交换柱上完全分离异丁酸和丁酸。五名健康受试者的VFA（通过GLC测量）的平均（±标准差）百分比分布值分别为56.0±3.5（乙酸）、17.0±5.3（丙酸）、2.9±1.5（异丁酸）、18.8±5.8（丁酸）、2.3±1.2（异戊酸）和2.9±0.8（戊酸）。
