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Split Injection Makes for Easier Polar Solvent GC Work versus Splitless Injection

30 Mar 2016

As anyone who's doing QuEChERS knows, analyzing acetonitrile extracts on nonpolar GC columns (like Rxi-5ms, e.g.) using splitless injection can be problematic because of the classic solvent - stationary phase mismatch.  To avoid split peaks we usually have an initial GC oven temperature slightly above the 82°C boiling point of acetonitrile (MeCN), but this causes tailing of early eluting peaks as they are not focused using the "solvent effect" or cold trapping.  Life is much easier if we can do split injection at, say, a ratio of 10:1, since instead of, e.g., 1 microliter, we now have approx. 0.1 microliter of polar solvent going onto our nonpolar GC column.  Of course you need to pay attention to the hit on your LODs and LOQs, but with more sensitive MS/MS instruments being developed every year, split injection for pesticide residue work is becoming practical.  Given that approx 10 times less extract goes onto the column and into the MS source, system uptime is greatly improved, too.  A Restek Premium Precision split liner with wool and "shoot-and-dilute" GC (split injection GC) makes life easier!


Split injection