Chromatography Forum

Hello folks,
Since I work at an undergraduate teaching university I'm always looking to minimize costs associated with undergraduate research. We have an Agilent 1100 with a G1313A autosampler equipped with a 20 uL injection loop. A student is attempting to replicate a method that used a 50 uL injection. Has anyone tried to make their own homemade injection loop using peek tubing? I came across this website http://www.ionsource.com/Card/loop/loop.htm and was wondering if this is a good or bad idea. The appropriate tubing would cost less than buying a 100 uL injection loop. Thanks.

Should be no problem. Bear in mind that the tubing is not precision-bore, so the final volume may not be exactly 100 microliters (but then that's true of store-bought loops as well).

Thanks Tom. We'll get it a shot.
Nadia

Hi Nadia,

Just wondering if you have tried injecting larger amount than 20 uL?
The G1313A is not a fixed loop injector but probe-in-loop style. You should be able to inject anywhere from 0.1 to 100 uL with this autosampler either by changing the volume in chemstation or via the gameboy if you don't have chemstation.

Hi Tom,
We did try to inject 50 uL and saw an increase in peak area but it wasn't as big as I thought it would be which prompted me to contact the vendor who informed me of the 20 uL loop. In reading "Introduction to Modern Liquid Chromatography (by Snyder et al), I attributed the increase to the fact that we were now overfilling the 20 uL loop which is what we should have been doing. However, just yesterday, while doing even more reading in Snyder et al and the autosampler reference manual, I began to better understand the nature of the autosampler's design. It occurred to me that (as you said) the loop size wasn't critical since the needle is part of the flow stream. I wasn't sure though. My previous experience was with a Shimadzu which I believe used a different design. Unfortunately, when we started the instrument yesterday we ran into more serious issues. The autosampler is now having an "Initialization Failure". The machine is still under warranty though. I purchased it in January but just put it together last month once classes were done. We are trying to use it as much as possible to put it through its paces before the warranty runs out. Thanks again for your valuable input!