GC测定醋酸中的乙醛残留量

Determination of Acetaldehyde in Acetic Acid by GC

关键词:  醋酸  乙醛  气相色谱法  顶空进样  药用辅料

Key words:  acetic acid  acetaldehyde  GC  headspace  pharmaceutic adjuvant

摘要:

目的 建立药用辅料醋酸中残留乙醛的测定方法。方法 醋酸用水稀释一倍后用等量的碱中和为盐溶液，立即密封后，采用顶空气相色谱法测定，以HP-INNOWAX石英毛细管柱(30 m×0.32 mm，0.5 μm)为分析柱，FID检测器；程序升温：35 ℃维持5 min，然后以30 ℃·min^-1升温至120 ℃，保持2 min；N₂流速为3.0 mL·min^-1；顶空进样：80 ℃平衡30 min。结果 醋酸的稀释避免了大量放热对测定的影响，中和生成的盐溶液提高了方法检测灵敏度，乙醛在10.73~ 107.3 mg·mL^-1(r=0.999 8)内线性关系良好，方法回收率为95.8％(n=9，RSD=5.0％)，最低检出限为2.5 mg。结论 用简单的顶空气相色谱法，解决了醋酸中痕量乙醛残留的测定问题，为其国家标准的修订奠定了基础。

Abstract:

OBJECTIVE To establish a GC method for determination of acetaldehyde in acetic acid used as pharmaceutic adjuvant. METHODS Acetic acid was diluted by water with the same volume, then neutralized by equivalent sodium hydroxide, sealed immediately and determinated by headspace GC. HP-INNOWAX capillary column (30 m×0.32 mm, 0.5 μm) was used as analytical column, FID detector was used. The column temperature rose by program: the initial temperature was 35 ℃, maintained for 5 min, raised to 120 ℃ with a rate of 30 ℃·min^-1, maintained for 2 min. The flow rate of N₂ was 3.0 mL·min^-1. The headspace injection was used, oven temperature was 80 ℃ maintained for 30 min. RESULTS The influence brought with exothermic reaction was avoided by the dilution of acetic acid, and the salt in test solution generated by neutralization reaction increased detection sensitivity greatly. The calibration curves were linear in the rang of 10.73-107.3 mg·mL^-1(r=0.999 8), the average recovery of acetaldehyde was 95.8%(n=9, RSD=5.0%). Limit of detection of this method was 2.5 μg. CONCLUSION The determination of trace acetaldehyde in acetic acid is solved by simple method of headspace GC, it establish the foundation for the revision of national drug standards.