By Anonymous on Monday, June 7, 2004 - 11:19 pm:

Dear Friends,
Can anybody help me in finding a way to perform gradient valve pair test required for calibration of a binary system? i have waters 1525 pump. Your help will be deeply appreciated

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By Anonymous on Tuesday, June 8, 2004 - 07:09 am:

There a quite a few ways to do it. Usually it is performed using some UV absorbing compound in line B, caffeine or acetone, in one solvent and none in the other. There are two different parameters to look at also. Linearity of the gradient from 100% A to 100% B and then the accuracy of the steps from 100% B to 100% A. The most critical area is around 50/50, where many systems have trouble. Mmany of the more recent systems have gotten over this problem at 50/50 though. If you use acetone as your UV absorbing compound, use a conc. of about .1-.3%. Good luck