Amino acid is one of the most important substances in organisms and the basic element forming enzymes and proteins. So amino acid analysis plays a vital role in biological researches. In this article, it is going to introduce some methods of amino acid analysis.
For those electrical activity amino acids, such as cystine, cysteine amino acid and tyrosine are usually analyzed with direct electrical analysis. Researchers can determine L-cysteine n phosphate buffer solution pH values less than 7 directly with the help of cyclic voltammetry.
Indirect electrochemical analysis
1.Using this indirect electrochemical analysis to determine most amino acids, which are electrochemically inactive and cannot be detected directly. This method can convert those into electrical active amino acids.
2.Matching amino acids and metal ions to detect that amino acids can be matched with many kinds of metal ions as a ligand. And then the complex electrical activity can be formed to improve their sensitivity.
3.Through the ECL analysis, researchers can learn that the ECL analysis has been widely used in analytic fields. ECL is a substance with ECL active. It also can react with redox reducing substances at a certain potential. It results in instable chemiluminescence. Recently, it is reported that the ECL method and IECL method are widely applied in analyzing all kinds of amino acids and proteins by scientists.
1.Derivatized ion exchange chromatography
The theory of amino acid analyzer is based on the cation exchange resin separation---three derivatisation spectrophotometric detection. This method is taking cation exchange resin as stationary phase and acidic buffer as mobile phase. And then adding ninhydrin to the column effluent to make amino acids generate derivative with the feature of visible absorption. It has the advantages of reproducible, stable instrument and reliable results.
2.Derivatization High Performance Liquid Chromatography
Derivatization High Performance Liquid Chromatography is applied in analyzing amino acids because of its advantages of shorter, flexible method, high sensitivity. And it has been replacing the use of derivatized ion exchange chromatography in many fields. It always adopts C18 bonded silica gel as the stationary phase and a polar solvent / weak acid buffer as the mobile phase.
3.Pre-column derivatization gas chromatography
Using gas chromatography method, researchers can save a lot of time and it is also known for high column efficiency, easy to be connected with mass spectrometer. Amino acids contain carboxyl, hydroxyl, amino and sulfur and other polar groups, which should be derivatized, including one-step method and two-step method.