第五章 高效液相色谱
Chapter 5:High Performance Liquid Chromatography
In U.S.Pharmacopoeia High Performance Liquid Chromatography(HPLC) is called Pressurized Liquid Chromatography.Due to its high pressure we can use smaller packing particles，smaller column.The high efficient of HPLC owes to that mostly.
在美国药典里，高效液相叫做加压液相。由于它的高压，我们能使用更小的填料颗粒，更小的柱子。高效相液的高效率主要就是依靠这个。
HPLC like the GC greatly，the concept of N，HETP，R，van Deemter equation can also be used for HPLC.Actually，HPLC mimic GC， pressurized gas change to pressurized liquid，airtight system to watertight system.But there are many difference between them.The inert gas commonly nonselective while liquid solvent do，the sample have to be volatile in GC while not in HPLC，GC is more sensitive to temprature，HPLC can load more sample than GC，GC is more efficient，etc.
HPLC很象GC，N，HETP，R，van Deemter方程等概念也可以用在HPLC。事实上，液相模仿了气相，加压的气体变成了液体，气密的系统变成了液密的系统。但它们之间也有很多不同之处。惰性的气体通常是没有活性的，而液体溶剂有；GC里，样品必须是挥发性的，而HPLC不必；GC对温度更敏感；HPLC载样量更大；GC效能更高，等等。
以下摘录一些文章和书籍中例句以供参考：
1.With this technology，liquid chromatography can give high-sped sepatations comparable in many cases to those achieved by gas chromatography，with the advantage that nonvolatile or thermally unstable materials can be chromatographed without decomposition or the necessity for making volatile derivatives.[U.S. Pharmacopoeia]
有了这个技术，液相很多时候达到的高速的分离可以与用气相达到的相比，并且有可以分析非挥发性和热不稳定物质而不会分解和不用做挥发衍生化的优点。
2.Temperature programming introduces many problems(e.g.，many good solvents cannot be used because of low boiling points，solvent degassers are required at elevated temperature，viscosity changes can adversely effect the results of the separation，etc.)，and in LC it is only a minor effect useful in special cases rather than an effective general substitute for solvent programming.[Handbook of Chromatography]
程序升温引起很多问题（例如，许多好的溶剂因为低沸点而不能用，升温时必须有溶剂脱气机，粘度改变可以极大的影响分离结果，等等），而且在液相中，它只有对少数特定的情况有很小的作用而不是溶剂程序改变的一个有效的通用的替代方法。
3.The introduction of spectrophotometers equiped with micro cells and detectors capable of operating at a additional wavelengths has extend the scope of ultraviolet detection.[U.S. Pharmacopoeia]
引入使用微池的分光光度计和可以在一个附加波长工作的检测器扩大了紫外检测的范围。
4.Although most workers have found that samples containing ionizable components usually are best separated with mobile phases that have a pH less than or equal to 3 ， some separations may be impossible at a low pH because components of the sample are unstable at a low pH; protonated basic compounds are eluted too soon; and required band spacings are unobtainable. [by J.J.Kirkland，LCGC Asia Pacific，1998，1(2)]
尽管许多工作者发现含有离子化组分的样品在流动相pH值低于或等于3的时候有最佳的分离，但许多样品不可能在低pH下分离，因为样品中组分在低PH下不稳定、质子化的生物碱洗脱太快、和不能达到要求的峰间距。
5.Silica gel is used as the support for normal phase chromatography;chemically bonded stationary phases for normal or reverse phase chromatography;octadecylsilane bonded silica gel is commonly used for reverse phase and ion pair chromatography; ion exchange resins used for ion exchange chromatography and silica gel or micropore glass beads for size exclusion chromatography.[Handbook of Chromatography]
硅胶被用作正相色谱的担体，化学键合相通常被用于反相色谱和离子对色谱，离子交换树脂用于离子交换色谱而硅胶或微孔玻璃珠用于分子排阻色谱。
