|Agilent||Shimadzu||Bruker / Varian||Perkin-Elmer|
Merlin MicroSeal - Introduction
The Merlin MicroSeal is a patented long-life replacement for standard GC septa and septum nuts on capillary or purged packed inlet systems.
The septum contains a series of seals (wiper rib, o-ring, and a duckbill valve) that allow a needle to enter while maintaining a leak-free seal. The septum can only be used with a syringe that has a 23-gauge (0.63mm) truncated cone or blunt tipped needle, or with an SPME fiber assembly with 23-gauge needle.
The MicroSeal is available in three versions for all major GC manufacturers’ instruments:
* General Purpose MicroSeal (formerly known as High Pressure MicroSeal) - this is recommended for use in most GC applications with injection port pressures between 3 and 100 psi (20 – 690 Kpa) and injection port temperatures between 50 and 400°C.
* Low Pressure MicroSeal (formerly known as the Original MicroSeal) - this is recommended for injection port pressures between 1 and 45 psi (7 -310 Kpa) and injection port temperatures between 50 and 400°C. Useful for fast GC/MS applications with 530 micron i.d. columns.
* SPME MicroSeal - recommended for SPME applications, using 23-gauge SPME probes.
How the Merlin MicroSeal Works?
The primary seal of Merlin when the syringe needle is not in place is a duckbill valve held in closed position by a stainless steel spring. This duckbill valve seals the injection port during analysis, but allows the needle to slide through without damage. The O-rings seal around the outer surface of the syringe needle during sample injection. The MicroSeal septum is made from high-temperature (400°C !), very wear-resistant fluorocarbon elastomer. In combination with proper needles the MicroSeal septum will not shed pieces into the injection port, even after thousands of injections.
The duckbill allows a very small amount of carrier gas leak through this primary seal. When a sensitive leak detector is used to sniff around the top of the Merlin nut it will detect (carrier) gas. With continued use it is possible for this carrier gas leak to increase due to wear or to small particles getting deposited in the duckbill. However, this small leak is at the top of the injector and is analogous to septum purge flow. Since the syringe needle deposits the sample in the inlet liner several inches below the MicroSeal, there is no effect on the injected sample. We do recommend, however, occasionally cleaning the septa with lab grade detergent, distilled water, and rinse with methanol.
Choosing the Correct MicroSeal
The choice of MicroSeal depends on whether you are operating at port pressures less than 3 psi or are using SPME. While there is considerable overlap in the pressure ratings for the P/N 310 and P/N 410 MicroSeals, the P/N 410 is preferred because it incorporates a wiper rib to remove particles from the needle. The diagram above illustrates the decisions in choosing the best MicroSeal version for both manual and automated injections.
|410||General Purpose Replacement MicroSeal (3 – 100 psi)|
|310||Low Pressure Replacement MicroSeal (1 – 45 psi)|
|21-01||SPME Replacement MicroSeal|
|For Agilent Ports|
|304||Low Pressure MicroSeal Starter Kit (Nut & 2 x 310 MicroSeals)|
|305||Low Pressure MicroSeal Adapter Kit (Nut & 1 x 310 MicroSeal)|
|404||General Purpose MicroSeal Starter Kit (Nut & 2 x 410 MicroSeals)|
|405||General Purpose MicroSeal Adapter Kit (Nut & 1 x 410 MicroSeal)|
|403||MicroSeal Nut for Agilent Ports|
|For Shimadzu Ports|
Kit for Shimadzu 2010 and 2025 ports
(Nut, Adapter & 2 x 410 MicroSeals)
|For Bruker / Varian Ports|
Kit for Varian 1079 ports
(Nut, adapter, O-ring & 1 x 410 MicroSeal)
Kit for Varian 1177 ports
(Nut, adapter, O-ring, spacer & 1 x 410 MicroSeal)
|For Perkin-Elmer Ports|
Kit for Perkin-Elmer ports
(Nut, adapter, O-ring & 2 x 410 MicroSeals)