GC直接进样和顶空进样法测定碘酊中乙醇浓度

Gas Chromatography Determination of the Concentration of Ethanol in the Iodine Tincture Using Direct Injection and Head-Space Injection

关键词:  气相色谱法  碘酊  乙醇  顶空

Key words:  gas chromatography(GC)  iodine tincture  ethanol  head space

摘要:

目的 分别采用GC顶空进样和液体进样器进样方式测定碘酊中乙醇的含量，并对2种进样方式进行比较研究。方法 采用Aglient DB-ALC1型气相色谱柱（30 m×0.53 mm，3.0 μm），FID检测器温度为250℃，柱温为80℃，进样口温度为200℃，N₂载气，柱流速为5 mL·min^-1，辅助加热区115℃。以叔丁醇为内标进行定量，采用顶空和液体2种进样方式，液体进样量1.0 μL，顶空进样量1.0 mL。结果 顶空进样时，乙醇在15.78~63.12 mg·mL^-1线性关系良好，Y=3.558 9X-0.341 3（R²=0.998 9）；回收率≥96.55%，RSD≤4.30%；日内精密度RSD≤3.86%；液体进样时，乙醇在15.78~63.12 mg·mL^-1线性关系良好，Y=0.015X-0.006（R²=0.999 5）；回收率≥97.8%，RSD≤3.22%；日内精密度RSD≤3.85%。结论 这2种方法均能准确地测量碘酊中乙醇的浓度，顶空进样法耗时较长但灵敏度比直接进样更高，对色谱柱的污染也较小，2种方法均能用于碘酊中乙醇含量的测定。

Abstract:

OBJECTIVE To establish and compare methods for detection of the ethanol in the iodine tincture by GC using direct injection and head-space injection. METHODS The ethanol in the iodine tincture was determined by GC with Agilent DB-ALC1 capillary column(30 m×0.53 mm, 3.0 μm) and FID detector, using nitrogen as the carries gas. The injector temperature was 200℃; the detector temperature was 250℃; the column temperature was 80℃. The flow rate of N₂ was 5 mL·min^-1, and the auxiliary heating temperature was 115℃. Tertbutyl alcohol was used as the internal standard, 1.0 mL sample was injected by headspace injector and 1.0 μL by direct injection. RESULTS With head-space injection, the calibration curves of ethanol had good linear relationship within 15.78-63.12 mg·mL^-1, Y=3.558 9X-0.341 3 (R²=0.998 9); the recovery was ≥ 96.55%; RSD was ≤ 4.30%; the within-day precision was ≤ 3.86%. The calibration curves of ethanol between concentration of 15.78-63.12 mg·mL^-1 by direct injection was Y=0.015X-0.006(R²=0.999 5), the recovery was ≥ 97.8%(RSD ≤ 3.22%); the within-day precision was ≤ 3.85%. CONCLUSION Both two methods are accurate and reliable, and can be used for the determination of the concentration of ethanol in the iodine tincture, and the method using head-space injection has more sensitive, less disturb and long analysis time than direct injection.