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Check visually (e.g. with a magnifier or under a microscope) for potential debris and/or acid blocking the needle tip- and sideholes and carefully remove it with a fine tip, e.g. with a pin.
If no waste is visible, try any of the following actions:
soak the needle in some milli-Q water and flush the needle with helium to dry it. If the blocking persists, soaking in ethanol instead can be helpful, though extra thorough drying should be performed afterwards.
try to carefully clean the two holes in the double-walled headspace needle with a thin wire.
flush the needle under higher pressure (e.g. 3 mbar) in order to remove potential remnants of septa or other acid inside the needle.
switch the capillaries, connecting the sample-out capillary to the sample-in at the back of the CHS2 to flush out particles from the side hole, applying either normal or higher (eg. 3 mbar) pressure. Make sure not to flush any liquid back into the CHS2, e.g. by disconnecting the capillary connection at the CHS2 that will lead the gas back into the CHS2.
depending on of the shape of the the needle’s tip, that may also lead to increased debris getting stuck in the in the sampling needle. It is possible to bend the very tip of the needle over the capillary with pliers. However, this has to be done very carefully in order not to bend or break the needle. The goal of this is for the needle tip to be in front of the capillary rather than leavin leaving the capillary in the needle exposed to the septa.
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