Archive for 2009

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 […]

Chloramphenicol analysis using gas chromatography?!

Chloramphenicol is an antimicrobial and suspected carcinogen, and is monitored in seafood, honey, and other food products, typically by LC (with MS/MS) because it is polar. You might think you’d never analyze chloramphenicol by GC, but recently at the National Metrology Institute of South Africa (NMISA), we had occasion to do just that. NMISA often […]

QuEChERS with dSPE A-OK at NMISA

QuEChERS is the popular “Quick, Easy, Cheap, Effective, Rugged, and Safe” sample preparation method for pesticides in fruits/vegetables that includes a dispersive solid phase extraction (dSPE) cleanup (shake extract with loose sorbent material, e.g. PSA, C18, GCB; more acronyms!). While in South Africa at ChromSA’s request to do GC training courses I had several slides […]

Donald Duck voices silent and birthday balloons fall everywhere as helium disappears…

I read in a news article that the world’s largest helium reserve in Amarillo, Texas will be gone in five years. Helium is a finite resource, and as a gas chromatographer, this is shocking to me, given that helium is the blood, the life force, for my work. Anyone using helium likely knows its cost […]

I’ll Take Mine on the (Moon) Rocks

Great minds think alike, which is probably why two polar research projects with related goals are occurring simultaneously. NASA went looking for (and found) frozen water on the moon. New Zealand, meanwhile, is preparing to recover Scotch whisky from Antarctica. Sounds like a fabulous drink recipe is waiting for a name. NASA’s study unfortunately did […]

Large volume splitless injection WITHOUT a PTV!

Recently while trying to create backflash in an Agilent splitless injector, I noted linear compound responses as I injected up to 25µL for PAHs from naphthalene to benzo(ghi)perylene! I went to the literature (note to self: start with the literature) and found papers from Magni and Porzano, and Grob’s group, where they termed the technique […]

Selectivity differences in arylene GC phases…pesticides and zebras.

Although not obvious even to a careful observer, no zebra has exactly the same stripe pattern. Fortunately for GCers, there isn’t that much variation in “5 type” columns, but users need to be aware that 5% pendant phenyl and 5% phenyl-as-silphenylene (or arylene) columns have slightly different selectivities. Recently we analyzed 31 pesticides on Rxi-5ms […]

Keep your nut warm this winter and improve GC pesticide response.

Hello from the Southern Hemisphere (Stellenbosch, South Africa), where the temperature is likely much warmer than central PA, my usual lab haunt. First, I’d like to acknowledge some chromatographers from this world area and encourage you to seek out their publications to know that innovative work is not the sole domain of the North. Ben […]

Maybe a rose is a rose is a rose, but a “5” is not a “5”, when it comes to pesticide analysis…

Greetings from South Africa, where I did a recent lecture on GC column selectivity and got the age-old question, “Are all “5” phases (5% diphenyl type) the same?” One easy answer, and you’ll certainly notice it if you are a pesticide chemist, is that the Rxi-5ms, a pendant-based 5% phenyl column, is definitely NOT the […]

USP <467> System Suitability…Where did my Carbon Tetrachloride go?

Achieving the sensitivity requirements for the Class 1 solvents in the revised USP can be, let’s face it, just plain difficult. By far, the biggest troublemaker is carbon tetrachloride in Procedure A. Sometimes a signal to noise ratio (S/N) of merely 3 seems a bit out of reach. Lets consider the concept of S/N for […]