Murayama K, Shindo N, Mineki R, Ohta K
Biomed Mass Spectrom. 1981 Apr;8(4):165-9. doi: 10.1002/bms.1200080407.
For the quantification of glutamic acid in Ringer's solution, pentafluoropropionic methyl ester was the most sensitive derivative. The detectable concentration was 0.01 microM glutamic acid in Ringer's solution; the amount of the preparation was 1 pmol and the injection into a gas chromatograph mass spectrometer was 10 fmol. For the quantification of gamma-aminobutyric acid in Ringer's solution, the trifluoroacetal-hexafluoropropionyl ester was quantification of gamma-aminobutyric acid in Ringer's solution, the trifluoroacetal-hexafluoropropionyl ester was detectable at a concentration of 0.01 microM. Ringer's salts facilitated acylation in the order heptafluorobutyric anhydride greater than pentafluoropropionic anhydride greater than trifluoroacetic anhydride. The effect depended on esterification of carboxy groups in the order methyl ester greater than hexafluoropropionyl ester greater than butyl ester. Sodium carbonate, sodium acetate and sodium citrate also facilitated acylation with pentafluoroproionic anhydride, while sodium phosphate inhibited the acylation and sodium sulfate inhibited it slightly. The pentafluoropropionic methyl ester of glutamic acid was stable for up to 10 days, when it was dissolved in acetone and stored at -18 degrees C.
对于林格氏液中谷氨酸的定量分析，五氟丙酸甲酯是最灵敏的衍生物。在林格氏液中可检测到的谷氨酸浓度为0.01微摩尔；制剂用量为1皮摩尔，注入气相色谱 - 质谱仪的量为10飞摩尔。对于林格氏液中γ - 氨基丁酸的定量分析，三氟缩醛 - 六氟丙酰酯在浓度为0.01微摩尔时可被检测到。林格氏盐促进酰化反应的顺序为：七氟丁酸酐＞五氟丙酸酐＞三氟乙酸酐。这种作用取决于羧基的酯化顺序：甲酯＞六氟丙酰酯＞丁酯。碳酸钠、醋酸钠和柠檬酸钠也能促进与五氟丙酸酐的酰化反应，而磷酸钠抑制酰化反应，硫酸钠略有抑制作用。谷氨酸的五氟丙酸甲酯溶解于丙酮并储存在 - 18℃时，可稳定长达10天。
