空气整段间隔流动注射分析的应用——茶叶中α-氨基酸总量的测定

The Application of FIA with Air-Bubbles Sandwich ( I ) ——The Determination of Total Amount of a-Amino Acids in Tea

用水合茚三酮以硫酸肼还原,与氨基酸反应的空气整段间隔流动注射分析法测定茶叶中α-氨基酸总量,只需90℃、5min测定下限就可达5mg/L,回收率在97～106％,进样频率80样/h。

The method of sample sandwiched between two air bubbles in FIA was used to determine the a-amino acids in tea. The hydra ted ninhydrin solution was added as a colour reagent and N2H4SO4 as a reductant. The use of N2H,SO4 instead of SnCI2 can accelerate the colour reaction and a higher sensitivity can be obtained. The detection limit can drop to 5 mg/L a-amino acid. The reaction was carried out at 90 癈 and the reaction time is reduced to 5 min. A small amount of TritonX-100 surfactant is used to keep the solution from depositing,thus a better reproducibility and a stable baseline can be obtained. In the measurement,the sampling frequency is 80 samples/h,the standard recovery is 97-106%, the related coefficient is about 0. 999 and the average relative standard deviation RSD is 2.6%. .