Cation exchangers are excellent columns for analysing simple mixtures of mono-, di-, and trisaccharides. Detection with RI is very stable, because the eluent is simple: just water! You have to use a vacuum degasser or to contineously heat the water to 80°C to keep it degassed. It is strongly recommanded to use a set of precolumns consisting of a strong cation exchanger in the hydrogen form and a strong anion exchanger in the hydroxide form (e.g. carbohydrate deashing set from Bio-Rad), which effectively removes all ions from your sample. Ions (including organic acids) can lead to interfering peaks and/or degradation of the ionic form of the analytical column (e.g. a cation exchanger in the Pb will loose Pb2+ when exposed to high concentrations of Na+.

Amino columns have the disadvantage that they react with reducing sugars (glucose, galactose, lactose), which lead to losses of these sugars and modification of the column. Moreover due to the use of a high percentage of acetonitril, the solubility of suars in the eluent is low. When sugars are dissolved in water only small injection volums can be used, because water is a very strong eluent (too large injection volume leads to distorted or even double peaks). Another drawback of this type of chromatography is that the response of sugars is relatively low (using RI detection) and that the noise and stability of the RI detector is much worse than those with water.

Last but not least: the eluent of the cation exchanger is green and costs almost nothing.

I have silver and calcium column but it shows different result especially in quantitative result than amino column

I tend to find the Resex columns tend more accurate for quantitative work than amino columns but that does depend on the detector. 4% and 8% crosslinking can impact separation as well. As Ivan and Pawel say the analyte and matrix are important to your decision. One point I find the use of a cation exchange resin SPE cleanup of samples is often required to maintain consistent separation because you can change the ionic form of the resin if you don't control for that. Talk to your Phenomenex contact about what you are trying to do and BioRad used to have a little Aminex book of tips as well that are suitable for a lot of the Resex columns.

Thanks all my samples usually food samples , like honey stevisoides, juices ,i show very low sugar % in honey sample than normal (ex glucose 1%) while it should be not lesss than 30 %

For sugar analysis mostly I use amino column. If your column is ion exchange column then it will give good results with amino acids.

I use Waters carbohydrate cartridge and its results are accurate and also, you have to carry out sample cleanup because it has an important role in the separation.

Cation exchangers are excellent columns for analysing simple mixtures of mono-, di-, and trisaccharides. Detection with RI is very stable, because the eluent is simple: just water! You have to use a vacuum degasser or to contineously heat the water to 80°C to keep it degassed. It is strongly recommanded to use a set of precolumns consisting of a strong cation exchanger in the hydrogen form and a strong anion exchanger in the hydroxide form (e.g. carbohydrate deashing set from Bio-Rad), which effectively removes all ions from your sample. Ions (including organic acids) can lead to interfering peaks and/or degradation of the ionic form of the analytical column (e.g. a cation exchanger in the Pb will loose Pb2+ when exposed to high concentrations of Na+.

Amino columns have the disadvantage that they react with reducing sugars (glucose, galactose, lactose), which lead to losses of these sugars and modification of the column. Moreover due to the use of a high percentage of acetonitril, the solubility of suars in the eluent is low. When sugars are dissolved in water only small injection volums can be used, because water is a very strong eluent (too large injection volume leads to distorted or even double peaks). Another drawback of this type of chromatography is that the response of sugars is relatively low (using RI detection) and that the noise and stability of the RI detector is much worse than those with water.

Last but not least: the eluent of the cation exchanger is green and costs almost nothing.

Thanks all

@kees many thanks for your help

(i use rezex column for monosaccharide to separate some honey sample , i get too low sugars % (for ex i got 1 % glucose also it must not less than 30% , i reapt my work several time , another person repeat the work with the same result , can i conclude from your that precolumn set can solve my problem

You can get only a too low result for glucose if there is a negative peak at the same retention time as glucose. Are there any negative peaks visible in the chromatogram at other places?

There are some organic acids and amino acids present in honey, but I would be very surprised that they can cause a negative peak at the position of glucose so large that it almosts completely masks the glucose peak (keep in mind that a RI detector can give positive and negative peaks)

What is your sample treatment?

no negative peak any where ,, the sample treatement ( 1 gm of sample were dissolved in 100ml deionized water sonicated , filtered through syringe filter PTFE 0,25 u pore size

Correct me if I am wrong: You are using an RI detector with an injected sample of 10mg/mL concentration. What volume are you injecting and is your mobile phase also water? The first thing that I would check is that have you suitably equilibrated the reference compartment of your RI detector. This could cause a loss of sensitivity. Additionally is the simple incandescant bulb used for RI detection in good shape? the same applies to the rest of the optical pathway. A loss of sensitivity is hard to explain if these simple parameters are OK. Of course I am assuming the differential referactive index mechanism is functioning properly. Any recent backpressure problems can very easily cause severe damage to this optical device. Run a standard check acording to your manual to check the operation of this feature, and also a calibration check with suitable standards. Good luck!

Hi,

I was using Agilent carbohydrate column for separation of sugars on RI detecor. I used it for food analysis. However the resolution of sugars decreased over a short period of time, inspite of the fact that I used a pre-column before the main analytical column. Then I found out that carbohydrate columns are based on silicon chemistry and tend to lose their amino grouos over a period of time, which results in loss of resolution. Therefore now I have shifted to a ligand exchange column from Phenomenex. The Rezex column is good. Only water needs to be used as eluent, no organic solvent required so the system is more environment friendly.

@ leo thanks alot for your help my concentation was 0.01 mg /ml my injection volume was 20ul , my mobile phase is HPLC grade water filtered and degassed temprature kept constant at 80 c ,i done check (at the same day i injected three sample one of them was normal with very good result