衬里的类型及其选择

GC入口衬里在将注入的样品转移到GC柱中起重要作用。它提供惰性表面，用于将注入的液体样品转化为蒸汽并转移到柱中而不改变其特性。

衬里可在不同的设计配置中提供或不停用和可选填料。衬里的选择是基于采用的样品类型和类型的注射技术。该主题涵盖了不同衬里的适用性，用于不同的注射技术。

基于注射类型的选择

Split Injection

Split injections are adopted when analyte concentrations are high and low level detection is not necessary. Such injections are made at higher flow rates and part of sample is led out through the split vent. The sample vapour spends less time in the liner. Such liners require rapid vaporization. Glass wool filled liners are chosen as they provide increased surface area and the injection needle is wiped during injections for improved repeatability. An unpacked liner should be preferred when analyzing active samples such as pesticides. In such cases glass wool packing can lead o formation of breakdown products.

Splitless Injection

不分流注射可用于痕量水平分析。优选使用失活的衬垫，使用失活玻璃棉将改善分析性能。羊毛有助于将样品从其蒸发的地方浓缩。此外，它通过防止非挥发性样品组分到达柱来延长柱的使用寿命。玻璃棉的位置可以帮助改善样品转移。当每次移除时，通过将注入的样品转移到玻璃棉中，通过将注入的样品转移到玻璃棉中来改善注射再现性。通过将其定位在衬里内的挡板之间，可以限制玻璃羊毛塞的位移。

Unpacked liners can be reused after cleaning but the cleaning process can lead to increased surface activity and contribute to poor performance.

直喷

当需要痕量测定时使用直接喷射，然后有可能降解活性样品组分。将样品直接注射到热入口中以使整个样品蒸发到GC柱中。这种衬里通常在底部配有压配合连接，配合并与柱子无泄漏。这种衬里在底部或顶部有一个钻孔。用底部孔衬里分析半挥发性化合物，对于水性溶剂样品，顶部孔衬里可以得到改善的结果。

可编程温度蒸发（PTV）注射

The sample is injected into a cold inlet which is then subjected to a heating program leading to the vaporization of the components for introduction into the column. PTV liners have small inner diameters and are provided with baffles to introduce turbulence and rapid heat transfer of sample to the column.

总之，衬里的选择取决于所选择的注射技术。对于具有停用表面和停用的玻璃羊毛包装的衬垫可以安全使用，以便在涉及活动组件的大多数应用中安全使用。然而，对于非常敏感的化合物，使用没有玻璃羊毛填料的衬垫。对于不需要蒸发的气态样品，需要衬里需要将样品有效地将样品转移到柱上。建议使用1.0 mm ID的窄孔衬里，以将样品引入柱中的尖锐带。