Chromatography Forum

Hello,

I'm doing low level analysis of perc (gc-msd) but I've got perc at 0.30 ug/l in my lines.

any suggestions on how to get it down?

I"m doing soil (methanol extract) and I usually add 200 ul of methanol to my purge tubes....I thought about using 400 ul of methanol to minimize the contamination effect. Any thoughts on that? is 400 ul of methanol too hard on the msd?

any help is appreciated. Thanks

mickygd,

Which lines, between autosampler and concentrator or between concentrator and MS or both? If first, disconnect transfer line at the concentrator and solvent rinse the lines with methanol. Or, disconnect the tranfer line and purge a really long time with no sample in the tube.

If between the MS and concentrator same applies but you will have to cap off or shut down the MS since the flow is coming from the concentrator.

Best regards.

It may be residing in the lines but it may also be residing in other parts of your system wither in the concentrator or the autosampler. What type of system do you have? If you are using and Archon or OI 4552 then you may want to also rinse out the upper soil valve and the associated fittings. I've seen contamination hang out in there before. If you're using something like the DPM 16's or 2016's then you may also have contamination in the 16 port valve in which case you're in for a fun day.