Read More
Date: 25-7-2018
2112
Date: 25-7-2018
2913
Date: 11-4-2017
1711
|
The Ninhydrin Reaction
In addition to these common reactions of amines and carboxylic acids, common alpha-amino acids, except proline, undergo a unique reaction with the triketohydrindene hydrate known as ninhydrin. Among the products of this unusual reaction (shown on the left below) is a purple colored imino derivative, which provides as a useful color test for these amino acids, most of which are colorless. A common application of the ninhydrin test is the visualization of amino acids in paper chromatography. As shown in the graphic on the right, samples of amino acids or mixtures thereof are applied along a line near the bottom of a rectangular sheet of paper (the baseline). The bottom edge of the paper is immersed in an aqueous buffer, and this liquid climbs slowly toward the top edge. As the solvent front passes the sample spots, the compounds in each sample are carried along at a rate which is characteristic of their functionality, size and interaction with the cellulose matrix of the paper. Some compounds move rapidly up the paper, while others may scarcely move at all. The ratio of the distance a compound moves from the baseline to the distance of the solvent front from the baseline is defined as the retardation (or retention) factor Rf.
|
|
اكتشاف تأثير صحي مزدوج لتلوث الهواء على البالغين في منتصف العمر
|
|
|
|
|
زهور برية شائعة لتر ميم الأعصاب التالفة
|
|
|
|
موكب أهالي كربلاء يستذكر شهادة الإمام الصادق (عليه السلام)
|
|
العتبة العباسية تستذكر شهادة الإمام الصادق (عليه السلام) بإقامة مجلس عزاء
|
|
أهالي كربلاء يحيون ذكرى شهادة الإمام الصادق (عليه السلام) في مدينة الكاظمية
|
|
شعبة مدارس الكفيل النسوية تعقد اجتماعًا تحضيريًّا لوضع الأسئلة الامتحانية
|