对羟基联苯法定量测定发酵液中的乳酸
首发时间:2007-05-29
摘要:对传统的对羟基联苯法进行了优化,应用于定量测定发酵液中的乳酸。首先对发酵液进行适当预处理,去掉蛋白质和葡萄糖,再利用正交设计对影响显色的几个重要因素进行了优化,结果最佳测定波长为565 nm,最佳显色条件为氢氧化钙0.05 g,20%硫酸铜0.8 ml,浓硫酸6 ml,0.5%对羟基联苯0.125 ml,静置时间15 min,加热显色时间5 min。标准曲线回归方程为A=0.0189C-0.0808(n=8),r=0.9989。在15~50ug/mL范围内呈良好线性关系。平均回收率为102.4%。显色稳定保持2h以上,RSD=2.6%(n=12)。该方法解决了传统对羟基联苯法显色时间长、准确度不高等问题,适合于发酵液中乳酸含量的测定。
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Determination of lactic acid in fermentation broth used P-hydroxybiphenol colorimetry
Abstract:An improved colorimetric method was developed for the determination of lactic acid in fermentation broth. Firstly, the fermentation broth was given a suitable treatment that the protein and glucose were removed, and then the traditional colorimetry method applied for the determination of lactic acid was optimized by the use of orthogonal experiment. The results showed that the best absorbency wavelength was 565 nm. The optimal colorimetric conditions were :0.05 g of Ca(OH)2 ,0.8 ml of 20 percent of CuSO4,6 ml of H2SO4,0.125 ml of 0.5 percent of p-Hydroxydiphenyl,15 minutes of reaction time and 5 minutes of heating time .Linear range was 15~50ug/mL (A=0.0189C-0.0808,r=0.9989).The average recovery was 102.4%. The determination of lactic acid by colorimetric method kept stable not less than two hours and RSD was 2.6%(n=12). The method established in this paper is quick, accurate and stable.
Keywords: lactic acid;determination P—hydroxybiphenol colorimetry ;orthogonal experiment
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