By Anonymous on Wednesday, May 12, 2004 - 11:16 pm:
We have a problem of broad and tailing peaks. The problem has raised in different columns, products and methods of analysis, so we are very confused. We have checked the three solvent chanels and they seem to work properly. The flow is correct.
The problem has appeared in different methods in the last weeks, but not in all of them (some methods have run correctly without problems).
Has anybody any suggestion? Thanks.
By Russ on Thursday, May 13, 2004 - 06:17 am:
Are these methods that have always worked well and now are not? Are they being run on more than one system? Has any work been performed on the system(s) recently? Is the injection volume the same for all the methods? You may already be aware of this but, if you are using permanently swaged fittings for your column connections and are changing between columns from Waters and manufacturers using "standard" fittings, you could have problems because the fitting dimensions are different. I have a vague memory (OK, most of my memories are vague) that you might be able to use tubing swaged for one of the columns on both but tubing swaged for the other column will only work for that column. For example (and I am not saying this is the way it is!) tubing swaged for "standard female" conncections might be able to be used on a Waters column, but tubing swaged for a Waters column may not be suitable for a column with "standard female" fittings. If you are not using permanently swaged column connections, this is a moot point.
By Tim on Thursday, May 13, 2004 - 08:15 am:
Do your systems have large loops, like the 1400ul needle seat capillary on an 1100? We found injecting volumes <<100ul with these installed gave broad/tailing peaks, so check you haven't put anything like that on. Also check if tubing has been replaced recently and large bore used.
By Henrik Vogelius on Wednesday, May 19, 2004 - 10:51 am:
As an HPLC column ages, the chromatographic peaks will broaden. When the
resolution is no longer acceptable, the column will have to be discarded. Other
causes of broad chromatographic peaks include high viscosity mobile phases and
large injection volumes. If just one peak in the chromatogram appears broad it
may be a late eluter from an earlier injection.