Linearity, response factor, splitless

[MestizoJoe]

Hi,

I was wondering why I would observe good linearity for one sample, A, and poor linearity for another, B. Both are injected in the same solution ranging from 3ppm to 0.5ppm.

A elutes in the initial temp conidions isothermally, and B elutes on a stable baseline after a ramp up to 90C.

% recovery for A is 100% + or - 5%.

% recovery for B is ~150% recovered at the 150% level and ~60% recovered at the 25% level. it looks like the response factor goes down with concentration on this on.

Any ideas? Much appreciated.

[carlos.teixeira]

Different analytes may show different response factors. Since A and B have each one its own retention time (based on your description I'm considering they are well resolved) and acceptable resolution you should up the sample amount for analyte B in a interval that does not disturb the good linearity results of analyte A. Reprocess your chromatograms using different conditions for B in order its peak areas goes up. Using this same aproach elevate injection volume till response factor B becomes better.

[Peter Apps]

Hi,

I was wondering why I would observe good linearity for one sample, A, and poor linearity for another, B. Both are injected in the same solution ranging from 3ppm to 0.5ppm.

A elutes in the initial temp conidions isothermally, and B elutes on a stable baseline after a ramp up to 90C.

% recovery for A is 100% + or - 5%.

% recovery for B is ~150% recovered at the 150% level and ~60% recovered at the 25% level. it looks like the response factor goes down with concentration on this on.

Any ideas? Much appreciated.

[MestizoJoe]

Just wanted to follow up on this. Component B, at first was eluting on a temperature gradient, though the baseline appeared stable. I've since changed it so that the temperature ramps up to a higher temperature, but B elutes on an isotherm. Now linearity is good.