How are Gas Chromatography (GC) and High Performance Liquid Chromatography(HPLC) different?
manbetx官方is an ideal technique for separation and identification of gases or volatile liquids having low molecular weights. The basis of separation is selective distribution of components present in gaseous phase on the solid adsorbent inside a column or on a thin liquid layer adsorbed on an inert solid support or on the inside wall of a capillary column. The range of separations can be increased by raising the column temperature in an isothermal or programmed manner.
高效液相色谱基于与气相色谱相同的原理，但用于分析具有较高分子量的热不稳定化合物。manbetx官方分离的基础是溶质分子在移动的液体流动相和色谱柱内的固定相之间的分布
It is very important to have a clear understanding of the differences between these two universally used separation techniques so that you can select the optimum technique for the required separation.
本文突出了两种技术之间的关键区别
移动阶段
HPLC中使用的流动相是液体，而在气相色谱的情况下是气体。manbetx官方由于液体的密度和粘度较高，因此需要泵通过HPLC柱驱动液体，因此背压很高。
分析物的性质
分析的样品HPLCare generally thermally labile and degrade at higher temperatures whereas in GC the solutes can withstand temperatures up to 400°C and are volatile in nature. Samples for analysis on HPLC are normally liquids or solids dissolved in liquids. GC can handle gases in addition to the liquids and dissolved solids. The molecular weights of GC samples are lower whereas HPLC can be used to analyze high molecular weight compounds covering a range of samples from high molecular weight polymers to large bio molecules.
列大小
Due to higher densities and viscosities of liquids in comparison to gases HPLC columns are generally short and wide. Typical dimensions are 10 or 25 cm with 0.46 mm id. Even larger columns have been used for preparative scale applications. On the other hand significantly longer columns with narrower bores are recommended in GC as gases are less dense and have lower viscosities. Capillary columns can be several meters in length.
工作温度
HPLCoperations are generally carried out at ambient temperatures due to the thermal labile nature of compounds. Gel permeation columns can be operated at temperatures in the range of 40 to 60°C. On the other hand gas chromatography columns can be heated up to temperatures around 450°C
Operating pressures
Liquids because of their higher densities and viscosities require higher pressures in the range of 5000 – 6000 psi for common analytical separations. UHPLC systems are capable of operation in the range 15,000 – 18,000 psi. The carrier gases in GC columns require lower pressures in the range of 150 – 200 psi
探测器
HPLC和GC都使用根据不同原理运行的检测器。
Common HPLC detectors
紫外探测器 -最常用的检测器
光电二极管阵列检测器 -同时进行多波长测定
荧光检测器 -高度敏感和选择性。通常需要衍生化合物以提高灵敏度
折射率检测器 -universal detector with limited sensitivity
电导率检测器 -good selectivity and sensitivity
Common GC detectors
火焰电离检测器（FID） -最常用的有机化合物
导热率检测器（TCD） -通用检测器。也可用于无机气体和永久气体
电子捕获检测器（ECD） -对卤化化合物的高灵敏度
氮磷检测器（NPD） -用于含氮和含磷的化合物
火焰photometric detector (FPD) –for sulphur and organophosphorus compounds such as pesticides and petroleum products
光电离检测器（PID） -适用于水和污泥样品中的芳香和不饱和化合物
HPLC和GC均已成功耦合到质量选择性探测器，以达到无与伦比的高分辨率和敏感性。这种组合在几个应用领域都取得了突破。连字符技术将在未来的文章中涵盖。
Dear Dr. Bhanot,
I greatly appreciate your efforts in enlightening us with the nuances of analytical chemistry. Your articles give us a paradigm shift and focus in understanding the subject whether it may be theory and/or instrumentation.
谢谢，
Hari, N.
Thanks Hari for your appreciation.Such kind words serve as a motivation in our efforts
谢谢博士。Deepak。一个非常丰富的话题。但是我想知道GC检测器的高温是否会影响注入的化合物，尤其是挥发性油标本。
嗨，阿米娜博士，
Volatile oils and other similar compounds are generally detected by GC using Flame Ionization detector which is a destructive detector which in any case burns up and destroys the injected compounds.However, the more volatile the sample the earlier it will reach the detector after separation in the column and it ts peak response will be seen before the other less volatile specimen components.
nice about hplc and Gc
plz削减了检测器和X射线光谱的工作基础
please Dr Deepak, what chromatographic technique is ideal for quantitative and qualitative analysis of aromatic halogenated compounds and what technique is also most suitable for determination of components of plant extracts that are required for antimicrobial sensitivity test.
可以使用带有电子捕获检测器的气相色谱法分析芳族卤化化合物。对于植物提取物，请指定一些化合物类别
你好，
非常感谢您的好课。
正在向您学到很多东西。
be Blessed
您能否将我引导到可以获得GC-MS和HPLC设备的地方，以分析印度的生姜精油及其成分。
可以在我们的实验室中进行所需的分析，但我们首先需要您的要求详细信息。您可以将详细信息发送给我的电子邮件ID[电子邮件保护]and provide me your complete mailing address and contact information. Regards