点样操作的好坏对于薄层层析有一定影响。例如点出的原点过大,往往在展开后呈现出的色斑大而不清晰,还会引起“拖尾”、“一条线”等毛病,给比拟值(Rf)的测定,混合物的分离带来一定的困难,甚至降低检出的灵敏度。一般要求点出的原点直径为1—2毫米。但用手持注射器点样,往往达不到上述要求,尤其是点样体积较大时(例如我们在分析粮食中亚硝胺时每次点样100微升),要保持原点直径在1—2毫米就更困难了,为此,我们制作了注射器夹持器来代替手持注射器的点样方法。在分析粮食中亚硝胺时,曾用改进的方法点样七十余次。在实际应用中认为该法装置简单,操作方便,效果较好。专门的点样仪器,国外也有报导,但装置较复杂, The quality of the spotting operation has some influence on the TLC. For example, the point of origin is too large, often showing large and unclear spots after unfolding, but also causes problems such as “tailing” and “one line”. The Rf value, the separation band of the mixture To certain difficulties, and even reduce the sensitivity of detection. General requirements point out the origin diameter of 1-2 mm. However, the use of hand-held syringes, often do not meet the above requirements, especially when the spotting volume is large (for example, we point out 100 microliters of nitrosamines in food), to maintain the origin diameter of 1-2 Mm is even more difficult, for which reason we have created a syringe holder instead of a hand-held syringe spotting method. When analyzing nitrosamines in foodstuffs, they have been spotted for more than seventy times in an improved way. In practical application, the method is simple, easy to operate and has good effect. Special point of the instrument, there are also foreign reports, but the device is more complex,