I have been using capillary electrophoresis to quantitate I+G in flavors. The one problem I cannot seem to overcome is that I need my samples have less ionic strength than the CE running buffer or the peaks disappear, time-shift, or get badly distorted and I can only really get the buffer concentration up to 250mM CAPSO ph 9.6 before I start having issues with resistance and heat dissipation of the capillary.
I was wonder if I could use an anion exchange SPE to concentrate my analytes perhaps elute with high level of formic or some other volatile acid then blow it down and redissolve in water?
Tell us some more about the nature and preparation of your sample, where does the high ionic strenght come from.
Why did you choose CE, maybe UPLC (with ionchromatography) offers better possibilities
At first, have to know the sample preparation protocol. Did u use ammonium acetate as buffer?
The high NaCl is inherent in the samples. They are flavors, usually powders with high amounts of NaCl added as much as 50% weight. Think stuff like chicken bouillon or the packets that go into rice or soups. I am wondering if I could use some sort of anion exchange SPE and elute with something like either formic acid or NH4OH and then evaporate and reconstitute in distilled water. Otherwise typical sample preparation for CE is dilute in water, filter, and inject.
I am currently working with HPLC-DAD though CE is cheap and easy. separating I+G via HPLC is tricky. It is generally done with a polar endcapped C18 column and 100% aqueous phosphate because otherwise they are prone to poor peak shape. On CE I get much better separation I can even separate deoxyinosinate which I use as an internal standard from Inosinate.
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