HP-PLOT U 色谱柱 说明：HP-PLOT U 柱是在熔融石英毛细管柱上涂渍并键合二乙烯基苯／乙二醇二甲基丙烯酸脂的色谱柱，它适于以下的分析：◆ 烃类（天然气、炼厂气、乙炔、丙烯气体，所有C1-C7和除去丙烯及丙烷以外所有的C1-C3异构体 ◆二氧化碳，甲烷，空气/一氧化碳和水 ◆极性化合物：在氯乙烯中的1,3-丁二烯；乙酸中的甲酸；水或气中的环氧乙烷；溶剂，醇类，酮类，醛类，酸类 ，胺类 HP-PLOT U 从60℃开始对许多烃类异构体（一直到c7、c1和C2所有异构体、空气/一氧化碳、二氧化碳和其他极性化合物都可以得到基线分离，这样一来要比从40℃开始分析，既提高了分离度又缩短了分析周期。 相似的固定相：PoraPLOTU;RTUPLOT 等温/程序升温温度范围：190℃ HP PLOT U 15m x 0.34mm x 10um HP PLOT U 30m x 0.32mm x 10um HP PLOT U 15m x 0.53mm x 20um HP PLOT U 30m x 0m53mm x 20um
I often get asked for advice on selecting the 'right' column, and among the characteristics that I ask people to consider are low bleed, a high maximum temperature limit, column inertness, and resistance to chemical degradation (primarily by oxygen, water, and extreme sample pH).
However, what customers usually have in mind is the 'right' column for getting the 'right' separation.
In this regard another question often crops up, which may be summarised as: "Should I be using a polar or a non-polar column?" Answering this second question is much easier and usually helps in providing an answer to the first.
Polar columns separate compounds on the basis of their polarity, whereas non-polar columns separate compounds purely on differences in boiling point. This is fine if there is at least 2C difference in boiling point between all the compounds in your sample. If there isn't, then it will be very difficult to separate them using a non-polar phase, even with a very long column. Examples of this can be seen with comparison analyses of xylene isomers
and FAMES, where you need to use much more polar phases to separate compounds according to differences in polarity, rather than relying on differences in boiling point. A guide to the polarity of various phase types is shown in Figure 3
If in doubt, it's a good rule-of-thumb to begin with a 5% phenyl column. These have just enough polarity to be able to separate a wide range of different compounds but are not so polar as to have low maximum temperature limits. This makes them useful for many different applications - indeed, approximately 75% of gc applications can be performed on this type of column and it accounts for 80% of global column sales.
When problems with co-elutions are encountered with a 5% phenyl column, or when a different elution order is required for confirmation of compound identities, mid-polarity columns, such as the 35% & 50% phenyl, can be used. These still have relatively high maximum temperature limits, so they can often be used in the same gc as a 5% phenyl column, and allows each sample to be injected only once and split onto the 2 separate columns.
So, in order to choose the right column for your application you need to know something about all the compounds you are trying to separate. Remember - this includes any contaminants that are likely to be in your real world samples, not just the compounds that are in the standard that you may be working with initially. Do they have boiling points that are different enough for them to be separated on a non-polar column? Or are the boiling points very similar? If this is the case, then are there differences in polarity that you exploit, using a more polar column?
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