Optimize The Compressibility Compensation Setting - Agilent Technologies InfinityLab LC Series User Manual

4 Optimizing Performance

Optimize the Compressibility Compensation Setting

Optimize the Compressibility Compensation
Setting
The compressibility compensation default setting is 100 × 10
pump. This setting represents an average value. Under normal conditions the
default setting typically reduces the pressure pulsation to values below 1 % of
system pressure that are sufficient for most applications and for all gradient
analyses. The compressibility settings can be optimized by using the values for
the various solvents described in
listed in the compressibility tables, when using isocratic mixtures of solvents and
if the default settings are not sufficient for your application the following
procedure can be used to optimize the compressibility settings.
When using mixtures of solvents it is not possible to calculate the
NOTE
compressibility of the mixture by interpolating the compressibility values of the
pure solvents used in that mixture or by applying any other calculation. In these
cases the following empirical procedure has to be applied to optimize your
compressibility setting.
Inappropriate settings would mainly affect retention times of peaks eluted at the
beginning of a gradient. Therefore optimize settings for the solvent at the
beginning of the gradient. For mixtures containing up to 50 % water, use
compressibility settings of water.
1 Start the pump with the required flow rate.
2 Before starting the optimization procedure, the flow must be stable. Check the
3 Your pump must be connected to a data system or Instant Pilot with which
4 Starting with a compressibility setting of 40·10
Agilent InfinityLab LC Series 1260 Infinity II Isocratic and Quaternary Pumps User Manual
tightness of the system with the pressure test.
the pressure and %-ripple can be monitored, or connect an external
measurement device to the analog pressure output (see
Connections" on page 202)
steps of 10. Re-zero the signal display as required. The compressibility
compensation setting that generates the smallest pressure ripple is the
optimum value for your solvent composition. If ChemStation (classic view) is
used and the ripple shown is positive, then the compressibility setting should
be decreased. If it is negative, it should be increased.
Table 18 on page 85. If the solvent in use is not
/bar increase the value in
-6
-6
/bar for the
"Electrical
84