Asahipak NH2 Column

Record: 477

Category: Column Problem
Product: NH2P-50
Sample:

Question
We have a customer who has been using a 150X2.0 mm Asahipak NH2 column about a month ago and started to see some shift in retention times for lactose and lactulose. He performed a cleaning procedure as follows:

I did follow the procedure to clean the column, one hour 0.01N HNO3 at
flow rate 0.1ml/min one hour DI water at flow rate 0.1ml/min one hour
0.01N NaOH at flowrate 0.1ml/min one hour DI water at flowrate 0.1ml/min

After the cleaning, it lost 4 times sensitivity. The retention time
remain the same. Do you have any suggestion?

Answer
I cannot come up with a good reason for the lost sensitivity, but our recommended cleaning procedure for the NH2P column is to use 0.1N (not 0.01N) nitric acid and 0.1N sodium hydroxide, both about 5-10 mL (wash with water in between as you suggested). Would you please ask the customer to try this condition? It may be that something that was adsorbed on the surface was started to dissolve and changed the column condition by using 0.01N solvents.

Pg. 19, 10 Column cleaning
http://shodex.net/data/downloads/Asahipak_NH2P_series_EJ_No.501-1.pdf

 
 
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