Milestone Srl MA213-003 – DMA-80 EVO – User Manual
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5.12.2 Create a new calibration
Before using the Direct Mercury Analyzer for the first time, the instrument must be calibrated using
prepared Standard solutions of Hg or Standard Reference Materials (SRM or CRM). The instrument does
not have to be re-calibrated every time, but the calibration curve should be checked every morning prior
to analyse unknown samples. The instrument has to be recalibrated only if the calibration check results in
10% higher or 10% lower than expected recoveries.
The instrument has to be also recalibrated when any of the major components are replaced. For example,
calibration must be performed when the catalyst and/or the amalgamator are replaced, or when the
oxygen tank or gas regulator is changed.
The calibration may be performed using two different approaches:
A: Performing calibration using few standard solutions via different volumes: it is the standard method
also used in our QC. We suggest a sample volume of up to 0.3ml. Thus, four to five standards are
required to cover the full range of DMA work, with a volume from 0,02 ml up to 0,3 ml.
B: Perform calibration using the same volume but different standard solutions: it is the method we
suggest for low concentrations (less than 1 ng). If you need to calibrate this range, it is important to use
the same volume for each point (usually 0.3ml), so you need a standard for each point.
Of course, the risk of error in standard preparation is higher so you must pay high attention in the dilution
steps. But when working in linear regression at low concentrations, you do not need many points.
Here below is reported the standard procedure type A which can be followed to make a standard and
common calibration curve valid for DMA -80 EVO dualcell and tricell configurations.
Anyway, the solutions or samples as well as weighing and ng points can be chosen by the customer
according to his need.
Dedicated calibration procedures for ultrarace and standard working ranges will be better explained in the
Tips & Techniques chapters.
Procedure:
1. First of all, choose the solutions or samples to use for performing the calibration curve in
according with working range.
2. In the main page of the software, go to Method page and choose the method to be used for the
calibration procedure. (you can create a new method or load an existing one). Usually this
method will be the same for all calibration points since the sample used for the calibration should
be the same for all points (you can also select the method for all points in the Measure/link page).
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