Pesticide analysis questions (maintenance-related)

[chemwipe]

For anyone in here who does pesticide analysis - do you have to do GC maintenance before each batch?

I regularly cut 1' - 2' from my guard columns, change my Presstight connectors, change out my liners and maybe once a week change my Siltek baseplates.

Anyone else do this on the daily? Just curious.

cw

[vballchemist]

This sounds familiar. Prior to each analytical batch we go through the same steps to ensure low breakdown.

[kdamme]

In our environmental lab:

We have on-column injections and change guard columns every +/- 2 days (50 samples) for ground-samples.

Groundwater samples are analyzed with large-volume injection with a guard column and a few metres of analytical column before the "real" analytical column. The guard column and few metres of analytical column are changed every +/- 2 weeks (70 samples).

For both systems: pesticides are still fairly good before the guard column is changed, but we also analyze PAH on these GC/MS and they tend to tail much earlier...

We have replaced the press-tight connectors as much as possible by a metal connector and ferrules. In our opinion this gives less leakage problems.

Kevin