Unraveling the Mysteries of Ghost Peaks: It’s Time to Pull the Sheet Off

This is not Casper The Friendly Ghost. Ghost peaks take up precious instrument time and keep us in the lab long after everyone else has gone home. Whether using a FID, PID, ECD, or MS; you will encounter ghost peaks. Those of us using a non-specific detector (i.e. FID) need not be lost when it comes to these elusive compounds. Shown in the figure are two EPA 8270 blank chromatograms (Internal Standards & Surrogates only) run back to back using a 5Sil MS column, 30m x 0.25mm x 0.25df. The interesting thing about this chromatogram are the three different types of ghost peaks shown: carryover (PAHs), O-ring bleed (triphenylphosphine oxide), and contamination (phthalates). The 2nd blank is relatively clean. Follow these tips: don’t overload your liner with sample, condition your injection port and column prior to analysis & do run a blank after high concentration standards or samples. Don’t be superstitious follow these rules and you will be on your way to a trouble free analysis.