Poor peak shape

[Rain1314]

Hi,

Any of you know the possible cause for this :

LC : Agilent 1290
MS : Agilent G6540
Mobile Phase : 70/30/01 : Acetonitrile/H2O/Formic acid
Method : Isocratic

1st run


2nd run


Is it due to column? I used another MS for 2nd run.

Best Rgd,
Crystal

[tom jupille]

Without knowing what kind and size of column and thd flow rate, it's impossible to tell. One possibility is that you're seeing an unretained compound, with the shape determined by the extra-column volume and mixing characterisrics of your system(s).

[Alp]

I wonder what type of column you are using, and what is the flow rate. If the plots are x-axis = retention time, then you are seeing about 20 seconds retention time in both instances (one plot is in minutes, the other in seconds).
Is this enough time to take your analytes out of the void volume and do some decent chromatography?

Is your run time long enough so late eluting peaks do not interfere with the next injection?

Are the samples prepared in solution that is similar in strength to the mobile phase (what is the organic/water percentage?)???

Alp