Technical data

64 Agilent 1290 Infinity LC System Manual and Quick Reference
3 Optimization of the Agilent 1290 Infinity LC System
How to Achieve Higher Sensitivity
The injection volume and the sample dissolution solvent are important in
controlling dispersion. Care must be taken that the compounds are focused at
the top of the column, to avoid peak dispersion due to the injection, which
would cause a reduced peak height. To achieve this, the sample should be
dissolved in a solvent composition of lower elution strength than the mobile
phase. It may be possible to increase the injection volume to have a greater
concentration of analyte on the column and hence increased peak height.
Refer to the comments in “How to Achieve Higher Injection Volumes” on
page 51.
Peak Width, Response Time and Data Collection Rate
The peak width setting, response time and data rate in the detector are all
linked. The available settings are shown in Table 8 on page 65. It is important
to set this correctly for optimum sensitivity and to preserve the resolution
achieved in the separation.
The detector internally acquires data points faster than is needed for a
chromatogram and processes them to produce the signal seen by the data
system. Part of the processing reduces the data to an appropriate data rate
which allows the chromatographic peaks to be accurately drawn. As with most
analytical determinations groups of readings are effectively averaged to
reduce error in the result. The detector bunches raw data points and produces
the output signal data at the required data collection rate by an electronic
filtering process. If the resulting data rate is too slow (over filtering) the peak
heights will be reduced and the resolution between them reduced; too fast and
the data is noisier than it need be to accurately profile narrow peaks.