We are trying to analyze 3000ppm dimethyl zinc in hydrogen balance gas. On our first attempt, we wound up with a delivery system, sample valve, and column full of white ZnO2 because of O2 and moisture. We have since had almost the entire delivery system Silcosteel treated, installed a tee with a valve and N2 source to purge the delivery system while heat tracing the lines and sample valve, replaced the column and any tubing and fittings that were contaminated with ZnO2 before. Our first few injections with this new system were pretty successful. We saw a small methane peak and a very large DMZ peak. On successive injections, the DMZ area was reduced, but not greatly and we had a good analysis with about a 0.4% RSD. When we changed cylinders, the analysis deteriorated quickly. The methane peak grew while the DMZ peak shrank and eventually we wound up with all methane and no DMZ. Our guess is that we did not purge enough when the cylinders were switched out, but the strange thing is we didnt' find any white coating on the system anywhere when it was disassembled. About the only other strange thing is that we have had to increase the hydrogen flow on the detector to keep the flame lit. The detector was cleaned when the system was contaminated the first time.

We are using an Agilent 6890 with FID detector, hydrogen carrier, a 30 meter x 0.53mm x 2.65um HP-1 column.

If anyone has any experience with this chemical and the analysis of it, I would greatly appreciate a response. Thank you.