Editorial Article: Choose the Right GC Syringe for your Application

GC Consumables Series Part 1
GC consumables play a vital role in an analytical laboratory. Discover how selecting the right GC syringe for your specific application enables fast, efficient analysis with a significant reduction in downtime. When selecting the perfect GC syringe for your application, whether the injection is manual or autosampled, it is important to consider the following factors:

•  Needle type
  Each injection port is designed differently and requires a specific length of syringe to be used. For reproducible sample transfer from liner to column, injection ports require the sample to be injected at a specific depth inside the inlet liner.
  

• Needle Tip Style
  Selecting the correct needle tip allows the best performance to be achieved. For example, cone tips are the most versatile for autosampler use and resist coring of vial and inlet septa. Bevel tips are typically used for manual injections. Side hole tips are usually used for headspace and large volume injections. Blunt end tips are used for injectors that do not contain an inlet septa. Dual gauge tips have both a narrow gauge and a wide gauge section – the narrow gauge is suitable for megabore on-column injection, and the wider part is suitable for autosampler use.
  

• Needle Gauge
  This is a measurement of the thickness of the needle. The higher the number, the thinner the syringe. Selecting the correct gauge is critical for on-column injections, as the syringe must fit inside the capillary column.
  

• Needle Attachment
  Syringes are available in both fixed and removable needle designs.
  

• Syringe Volume
  In general, using a sample volume lower than 10% of the maximum syringe volume will reduce the precision of the injection. For liquid sampling, volumes are typically between 0.5-3µL, so the most common syringe volumes are 5 and 10µL.
  

• Plunger Design
  Most plungers are made from stainless steel, with the option of a PTFE tip on the end. If a PTFE tip is present, the syringe is classified as gas-tight and suitable for gas and liquid sampling. If there is no PTFE tip, the syringe is not gas-tight and should only be used for liquid sampling.