Merlin Microseal


The Merlin Microseal is a microvalve alternative to the conventional silicone rubber septa used in gas chromatography (GC). Its unique design gives it high pressure capability and resistance to wear which results in long life and excellent chromatographic performance. The Microseal is available for all major GC manufacturers’ instruments.


Eliminates septum coring and crumbling into the injection port liner

Reliable performance during extended runs

O-ring detail seals needle during injection

Duckbill seals more tightly at higher pressures

Low insertion force for easy manual injections

How It Works

A GC injection port septum performs two discrete functions: it seals the port while the syringe needle is inserted and during analysis after the needle is removed. The Microseal reliably seals the port in both situations without being punctured.

Microseal Operation Step-by-Step

  1. Pressure in the injection port, aided by the spring, squeezes the duckbill closed and maintains a tight seal on the port. Higher pressures seal it more tightly.
  2. As the syringe needle enters the Microseal, the wiper rib removes any particles adhering to the needle.
  3. The O-rings of the syringe seal then make a sliding seal around the needle.
  4. As the needle penetrates further, the tip pushes the duckbill valve open and slides into the injection port. The syringe seal maintains the seal around the needle.
  5. After sample injection and as the needle is withdrawn from the Microseal, the spring pushes the duckbill valve closed before the needle leaves the syringe seal. The port remains sealed during the injection process.

The Merlin Microseal is distinct from traditional septa in that the Microseal has two independent sealing mechanisms to perform these functions. A set of O-rings seal the syringe needle during sample injection. A duckbill valve seals the injection port during analysis but allows the needle to slide through it without damage. 

In contrast, a conventional septum is repeatedly pierced by the syringe needle and eventually leaks or sheds septum particles into the injection port liner. These particles can cause sample adsorption and decomposition and can contribute ghost peaks to a temperature programmed chromatogram.

The Microseal eliminates the coring and crumbling of traditional silicone rubber septa. Because the two seals perform separate, individual functions and are only slightly distorted in operation rather than being pierced, the Microseal septum can be made from a high-temperature, very wear-resistant fluorocarbon elastomer. In combination with the blunt needle, this means the Microseal septum will not shed pieces into the injection port, even after thousands of injections.

Microseal types

General Purpose Microseal

Low Pressure Microseal

SPME Microseal

26 gauge Microseal

Microseal for Thermo Trace 1300 cold on-column GCMS (26 ga)

19 gauge Microseal

Microseal for PAL SPME Arrow

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Microseal For

Agilent GCS

Shimadzu GCS

Thermo Scientific GCS

PerkinElmer GCs

Scion/Varian GCs

SPME Arrow Probes

SPME Analysis



Merlin Instrument Company

7000 S. Broadway, STE 1A

Centennial, CO 80122

 +1 303-794-4135

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Merlin MicroShot and Merlin MicroSeal are trademarks of Merlin Instrument Company
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