Using the Merlin Microseal for SPME
Microseal is the Preferred Choice
The two separate sealing mechanisms of the Merlin Microseal make it the preferred choice for Solid Phase MicroExtraction (SPME). The duckbill seal allows the SPME probe to push through while the O-rings maintain a seal. (See How the Microseal Works.) SPME probes typically have square or beveled ends which can core or damage conventional silicone rubber septa. This results in short septum lifetimes and often causes septum crumbs to fall into the injection port liner, where they can interfere with the analysis.
As a solution to this problem, the Microseal is recommended by manufacturers and distributors of SPME probes and is specifically required for beveled tip probes. The Merlin P/N 21-01 Microseal has been developed specifically to resist wear when used with SPME probes.
The Microseal requires 23 ga SPME probes to seal properly during desorption. Do not use 24 ga probes. They are too small in diameter to seal in the Microseal.
Microseal Compatible SPME Probes
The orientation of the bevel on the SPME probe with respect to the Microseal is critical so that the beveled probe can push through the lips of the duckbill without damaging them. Incorrect orientation of the bevel on the probe will cause the tip to pierce or damage the inside surface of the Microseal. The figure below shows the correct orientation of the bevel with respect to the Microseal. A suggested procedure is to record the orientation of the Microseal in the port and then to install the SPME Probe in the autosampler so that the bevel on the probe is aligned properly as shown in the figure.
Performance and Troubleshooting
The 21-01 Microseal should last for over 1,000 insertions when used with SPME probes. If you are experiencing fewer than this, please email us.
In our testing, the P/N 410 General Purpose Microseal will also give reasonable lifetimes with square tipped probes but is not recommended for use with beveled probes.