Passivation of injection needle
Posted: Wed Sep 02, 2009 11:24 am
by Mattias
Do you perform passivation of injection needle when you passivate the rest of the LC?
is it possible to inject 30% HNO3, or will it damage the seals?
Posted: Wed Sep 02, 2009 12:01 pm
by rhaefe
depends on the material of the seal but I would say they can handle 30%nitric acid. I have passivated needles and injectors in the past on following instruments:
HP1090, Agilent 1100, Hitachi/Merck La Chrom. In at least one case I had a stubborn contamination. I removed the injection needle from the system and cleaned it in 69%nitric acid for about 30 minute using an ultrasonic bath. Worked really well.
Make sure that the parts are free from any organic solvent (especially alcohols) and use a separated waste container to catch the nitric acid.
Robert