AR 33947, p/n 2109392, s/n N105706,

Record: 436

Category: Column Problem
Product: OEM NH2P
Sample:

Question
We have a customer having an issue with a prevail carbohydrate ES column (information above). The complaint column is different from other old columns. The retention time is shorter and the area is larger. The test conditions are all the same. Can you please look further into this and let me know what you find. The mobile phase is acetonitrile :H2O 75:25 flow rate 1.0ml/min, column temp 30℃, pressure 73bar, injection 8ul during the test there is no guard cartridge, the sample is standard of fructose glucose sucrose maltose, to my surprise, the customer dissolved the standards with 5% methanol and water, but I believe this will not the main cause to lead the retention time become shorter than old columns. He said he always using this method to test his sample either old columns or the complaint, but I suggest using the mobile phase to dissolved the standards.

Answer
As you caught, the solvent used for the sample preparation could be a part of the reason. Please take a look at the attached pdf. ACN concentration affects the peak shapes and slightly but retention time. I understand that the customer is saying that they’ve always used the same sample preparation method and at this point we don’t have a good explanation for it.. However, if they can achieve an improved peaks from using 70%ACN for the sample, I think they will be happier…
One comment, they should use small amount of water to dissolve the standards, then add corresponding amount of ACN to make the final ACN concentration 70-75%.

 
 
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