AZURA® Detector RID 2.1L / RID 2.1L HighFlow Instructions V6750
28
Product information
7.2.1 Autozero
The autozero command leads to the zeroing of the detector signal. This
command can be carried out via software or via analog command.
This is a two leveled function:
Level one is an electronic or digital zeroing of the signal.
Level two is an automatic zero glass adjustment. Level two is car-
ried out automatically when the baseline drift exceeds a permitted
threshold.
The autozero function generates a numeric offset value “a”, employed in
the calculation of the detector signal (see 1.5.2 on page 5).
By default, an autozero command is automatically carried out at the start
of a run.
7.2.2 Temperature control
It is possible to select the temperature of the optical unit in the range
30–55 °C in 1 °C steps via software. It is recommended to set the tem-
perature 5–10 °C above the ambient conditions, in order to improve and
ensure baseline stability.
The default values are listed in a separate section (see 7.2 on page 27).
Note:
For the AZURA® Detector RID 2.1L HighFlow, the temperature con-
trol is only effective up to a flow rate of 50 ml/min.
7.2.3 Signal mode
According to the relative refractive indexes of eluent and analyte, it is
possible to obtain positive or negative peaks in your chromatogram (also
in one run). Positive peaks result when the analyte has a greater refractive
index than the eluent. Negative peaks result when analytes have a lower
refractive index than the eluent. You can convert the signal of your peaks
(direct or inverted) in your chromatogram via the signal mode option in
your software.
The default values are listed in a separate section (see 7.2 on page 27).
7.2.4 Time constant & data rate
The time constant influences the response time of the detector. The
response time determines how quickly the detector responds to a
change in signal. A good thumb rule for selection of the time constant is
that it should be no larger than the baseline peak width of the first peak
of interest (in seconds). Increasing the time constant allows more averag-
ing of the signal (also known as digital filtering) and results in less base-
line noise. However, increasing the time constant too much may result in
broad peaks, reduced peak heights and asymmetric peak shapes. There-
fore, a compromise has to be found.
Using the time constant a signal smoothing can be achieved. The larger
this value is set, the more the signal will be smoothed. In general, the
best time constant is the reciprocal of the data rate (see table below). If
increased sensitivity is desired, or if the baseline noise is interfering with
integration, the time constant should be increased. If resolution is com-
promised, it should be decreased.
Response time
Time constant
