分光光度法测定发酵液中L-精氨酸含量

建立了定量测定发酵液中L-精氨酸含量的方法。以百里酚的次溴酸钠溶液为显色剂,用正丁醇萃取显色产物,以分光光度计比色测定有机相的吸光度值。测定发酵液中L-精氨酸的最佳条件为:取待测物稀释液5.0mL,依次加入0.03%的百里酚溶液2.0mL,0.7%的次溴酸钠溶液0.5mL,摇匀,30s内加入正丁醇5.0mL,除去水相;向有机相中加入0.4mL无水乙醇,室温放置1min,用分光光度计测定OD480。方法的检出限为2.5μg/mL,摩尔吸光系数ε为1.2×104L/(mol.cm),发酵液样品相对标准偏差为0.89%～1.10%,回收率为97.3%～102.0%。此方法简便、快速、准确可靠,适合用于发酵液中L-精氨酸含量的定量检测。

Speetrophotometric Determination of L-arginine in Fermentation Broth

Using thymol-sodium hypobromite as chromogenic reagent,and extracting the colour formed with butanol,a spectrophotometric method for the determination of arginine in fermentation broth was studied.The optimal conditions were established:2.0 mL of 0.03% thymol,0.5 mL of 0.7% sodium hypobromite were added in 5.0 mL of appropriately diluted broth.The test tube was energetically shaken,and then 5.0 mL of butanol was added within 30 seconds,the aqueous layer was withdrawn and discarded;the organic layer was added 0.4 mL of absolute ethanol and its OD value was measured at 480nm.The determination limit of the method was 2.5 μg/mL,its apparent molar absorptivity was 1.2×104 L/(mol·cm),its RSD of fermentation broth sample were 0.89%~1.10%,and recoveries were 97.3%~102.0%.The method presented in this paper is accurate and reliable,and it is suitable for determination of L-arginine in fermentation broth.