摘要
建立了测定柠檬酸的多波长分光光度法。在pH 6.15的Tris-盐酸缓冲溶液中,灿烂绿与柠檬酸在可见光区发生褪色反应,生成具有3个明显负吸收峰的绿色离子缔合物,并出现褪色现象。最大、次大和最小的负吸收波长分别位于652、582和426 nm处。柠檬酸在0.02~3.84 mg/L(652 nm和582 nm)和0.48~3.84 mg/L(426 nm)内遵从比尔定律,表观摩尔吸光系数(κ)分别为3.33×10~4、2.84×10~4和1.44×10~4L/(mol·cm),定量限为0.019 g/100 g(652 nm和582 nm)和0.45 g/100 g(426 nm)。采用双波长或三波长叠加法测定,它们的灵敏度分别可达6.16×10~4L/(mol·cm)和7.61×10~4L/(mol·cm),定量限均为0.019 g/100 g。还探讨了适宜的反应条件、主要分析化学性质及络合比。方法用于新鲜柠檬中柠檬酸含量的测定,回收率为98.85%~101.1%,相对标准偏差(n=6)为2.2%~2.5%。
A fast multi-wavelength color fading spectrophotometry for quantifying citric acid in fresh lemon was developed. In Tris-hydrochloric acid buffer pH 6.15 solution , brilliant green reacted with citric acid to form a green ion association complex with obvious three negative absorption peak and bleaching effect in visible area. The maxi- mum and the second largest and the smallest negative absorption wavelength was located at 652 nm and 582 nm and 426 nm respectively. Beer＇s law was obeyed in definite mass concentration range within 0.02 -3.84 mg/L（652 nm and 582 nm） or 0.48 - 3.84 mg/L（426 rim） of citric acid. Their apparent molar absorptivity （to） were 3.33 × 104 and 2.84 × 104 and 1.44 × 104 L/（mol cm） respectively with the limitation of quantitation of 0. 019 g/100 g（652 nm 582 nm） and 0.45 g/100 g（426 nm）. The sensitivity of double wavelengths or three-wavelength superposition were 6. 16 × 104 L/（mol cm） and 7.61 × 104 L/（mol cm） respectively with the quantitative limits were 0. 019 g/ 100 g. The optimum reaction conditions, the main properties of analytical chemistry and the compound ratio were studied. The method were applied to determine the content of citric acid in fresh lemon with spiked recoveries and RSD% （n =6） in the ranges of 98.85% - 101. 1% and 2.2% -2.5% respectively.
出处
《食品与发酵工业》
CAS
CSCD
北大核心
2017年第4期228-231,共4页
Food and Fermentation Industries
基金
重庆市教委科技基金资助项目(KJ1401226)
长江师范学院科技基金资助项目(2015CXX080)
关键词
柠檬
柠檬酸
灿烂绿
单波长
双波长
三波长
褪色反应
分光光度法
lemon
citric acid
brilliant green
single wavelength
double wavelength
three-wavelength
color-fa- ding reaction
spectrophotometry
作者简介
江虹,学士，教授, 通讯作者，E-mail：jianghongch@163.com
