Archive for 2014

Broken fused-silica columns – it’s rare, but it does happen.

Once in a while we get a call that one of our GC fused-silica columns has broken, and customers ask if it can be repaired and used.  The answer is “maybe”. If your column broke while at a high temperature, and the column’s phase has been exposed to oxygen (air), then probably not.  A sure […]

Measuring Capillary Column Flow: “To ProFLOW or not to ProFLOW, that is the question”

Occasionally the Restek Technical Service group gets a request from a customer for information on how to measure the carrier gas flow from their capillary column with the Restek ProFLOW 6000 Electronic Flowmeter.     Although this electronic flowmeter is designed to measure volumetric flow for gases across a range of 0.5–500 mL/minute, there are […]

This RAVE won’t keep you up until the wee hours of the morning…

Our new air canister valve (RAVE™) won’t keep you up until the crack of dawn, because you can sleep peacefully knowing the following information (also available in the following video for those non-readers): Our valve is 100% stainless steel. This includes all of the wetted surfaces, which for the record have no moving parts. What does […]

How Dirty Are You? Part 4…Manual Syringe Rinsing…The Answer

So how many times do you need to rinse a syringe? Well, I can tell you the answer for the experiment we did. Let me first refresh your memory on specifically what we did. Sequence of manual syringe rinsing: 1. 20 µL draw of a 500 ppm hydrocarbon standard and expel it 2. 20 µL […]

Peak Capacity in Capillary GC

Peak Capacity in capillary gas chromatography is different than sample loading capacity, which is something I’ve posted on multiple times recently in ChromaBLOGraphy.  Peak capacity is simply the number of theoretical peaks that can “fit” inside a chromatogram under some definition of how much they should be separated (e.g. baseline resolved or some other criterion).  […]

Alternate GC Carrier Gas: Helium to Nitrogen, 30m x 0.25mm x 0.25µm Column to 20m x 0.15mm x 0.15µm Column

I sent my earlier post, “Switching from Helium to Nitrogen Carrier Gas for GC by Switching from a 30m x 0.25mm x 0.25µm Column to a 20m x 0.15mm x 0.15µm Column” to Roy Lautamo at Restek West for review, as he has a critical eye for particulars.  He wanted to see finer detail in […]

Another cup of PAH tea please!

It seemed not too long ago that Julie Kowalski and I were analyzing tea, a lot of tea, and only tea.  To this day we cringe at the thought of tea, but hopefully our pain can be your gain. We analyzed pesticides, natural products, and polycyclic aromatic hydrocarbons (PAHs) in tea.   Julie and Amanda Rigdon […]

Switching from Helium to Nitrogen Carrier Gas for GC by Switching from a 30m x 0.25mm x 0.25µm Column to a 20m x 0.15mm x 0.15µm Column

Our own Jaap de Zeeuw is a master chromatographer and he sometimes does his best work while sleeping.  Recently he was sharing with me an idea that woke him up in Singapore at 3 AM about switching from helium carrier gas for GC, which is still under threat from a supply shortage, to nitrogen, an […]

How Dirty Are You? Part 4…Manual Syringe Rinsing…The Question

This How Dirty Are You? blog should really be credited with inspiring the entire project. I was discussing the number of times I rinse my syringes with a colleague, Michelle Misselwitz, a few years ago. We were working in the same hood and I noticed that she rinsed her syringe a lot…I do too. I […]

Does a different oven temperature programming rate change overload for PAHs on a GC column?

Jaap proposed that it might make a difference, so I wanted to test that possibility and add it to the following series on sample loading capacity, or “loadability” as Jaap calls it, for gas chromatography. Sample loading capacity for PAHs on a 30m x 0.25mm x 0.25µm Rxi-5ms GC column Does a thicker film GC column increase […]