related substance of glimepiride

[amitavaghosh]

recently i am working in glimepiride rs, according to usp the mobile phase is 2.5 phos buffer and acn=50:50 and diluent is acn:water=4:1. sample preparation in below 12.0°c. but in purosphere column i am getting urethane and one unknown peak sometimes separated sometimes merging and in lichrosphere column urethane peak is well separated but the unknown peak is sometime coming and sometime not coming. now where is the problem, is it phmeter problem or sample preparation problem or column reproducibility problem.

[shirish]

GOOD Question

Seems to be Column sample preparation and Column Reproducibility issues, Try different Brands of Columns

[Mark Tracy]

You can eliminate the pH meter by making your buffer by weight. Once you know the weights of conc. H3PO4 and KH2PO4 that make a good mobile phase, just do it that way every time. In fact, you can weigh the water, K2HPO4, H3PO4 and acetonitrile. Whenever we need highly reproducible retention times, that is standard practice here at Dionex.

[Narendra]

Try to find out raw material really pure or it content some other impurity which is some time get separated and some time not. It may be because of Change in PH of mobile phase, Change in Column, peak due to previous run etc.