Dear friends,

We are trying to measure dioxin/furan with HP 6890-MS 5973 having Negative Chemical Ionization (NCI) mode. We have been applying different working conditions and oven temperatures for standrads having 17 PCDD/F congeners (max conc. = 500 ng/ml, min conc. = 100 ng/ml, the amount of injection = 2 microliter) for approximately one month. However, we have not seen all of the 17 congeners yet. Morever, there is no stability on the congeners that we have seen (pentachlorofuran and hekzachlorofuran are generally observed). What could be the problem?

Is there anyone who worked on PCDD/F analyses with NCI mode in this forum? If so, what was your working conditions (MS temperature, source temp., oven temp., prog., injection temp., quadropole temp., etc)? Moreover, any help on the column info (length, ID, film thickness, max. column temp, etc) would be beneficial.

Your help will be greatly appreciated. Thanks in advance.

K. Korucu, Graduate Student.