As noted in earlier blogs, “Fast Organochlorine Pesticide Analysis Using Hydrogen Carrier Gas with Split Injection GC-ECD” and “Split Injection Minimizes Endrin and DDT Breakdown for GC-ECD Analysis of Organochlorine Pesticides”, split injection is a viable alternative to splitless injection for analysis of organochlorine pesticides (e.g. when using EPA Method 8081).
Notable benefits include:
1. Higher throughput due to the ability to start the GC oven at a higher oven temperature (faster analysis time AND less oven cool down time).
2. Greater uptime through initial, and ongoing, decreased breakdown of sensitive pesticides Endrin and DDT (faster flow through inlet liner during split injection versus splitless injection decreases compound residence time and chance for negative reactions or sorption).
Even after 145 used motor oil injections (4500 ng/µL – 1 µL injected, split 50:1), which led to heavily contaminated glass wool in the Precision split liner used for the work, EPA Method 8081 Endrin and DDT breakdown criteria were still easily met. In this case, used motor oil makes a convenient surrogate for “dirt”, or nonvolatile material that collects in the inlet liner and the front part of the GC column. This “dirt” is the common cause for Endrin and DDT degradation, and overall peak shape corruption in GC.
If you’re worried about meeting detectability requirements at a higher split ratio, don’t. The Agilent micro-ECD used for this work is VERY sensitive. See the first blog post above to confirm.