Haagsma N, Slump P
Z Lebensm Unters Forsch. 1978 Oct 30;167(4):238-40. doi: 10.1007/BF01135594.
A comparison is made between lysinoalanine (LAL) determinations both with an automatic amino acid analyzer (AAA) and with thin layer chromatography-densitometry (TLC) in different types of food and food ingredients, taken from the Dutch market. Generally there is a reasonable agreement between the LAL content obtained by both methods. However, some results indicate that a single technique is not always conclusive about the real identity of the ninhydrin-positive compound at the same position as LAL on the chromatogram. By TLC for instance, in yeast a content of about 800 mg of LAL/kg in protein is found, but according to the AAA method no LAL is present. In heated milk and milk products the LAL content determined by the TLC method is also higher than that found by the AAA method. This is caused by a preceding unknown ninhydrin-positive compound in TLC, occurring in all heated milk products and practically coinciding with LAL. In the AAA technique similar interferences of unknown ninhydrin-positive compounds could be avoided by choosing a suitable elution temperature; however, application of this temperature modification to foaming agents gave no satisfactory results.
对从荷兰市场采集的不同类型食品及食品成分中的赖氨酰丙氨酸（LAL），采用自动氨基酸分析仪（AAA）和薄层色谱 - 密度测定法（TLC）进行了测定比较。一般来说，两种方法所测得的LAL含量有合理的一致性。然而，一些结果表明，对于色谱图上与LAL处于同一位置的茚三酮阳性化合物的真实身份，单一技术并不总是能得出结论。例如，通过TLC法，在酵母中发现蛋白质中LAL含量约为800mg/kg，但根据AAA法，不存在LAL。在加热的牛奶及奶制品中，TLC法测定的LAL含量也高于AAA法测定的结果。这是由于TLC中存在一种先前未知的茚三酮阳性化合物，它存在于所有加热的奶制品中，且与LAL几乎重合。在AAA技术中，通过选择合适的洗脱温度可以避免未知茚三酮阳性化合物的类似干扰；然而，将此温度调整应用于发泡剂时，结果并不理想。
