Milestone Srl MA213-003 – DMA-80 EVO – User Manual
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2. CALIBRATION FOR ULTRATRACE LEVEL 0,1 ppb
Below is reported the procedure to calibrate the system a ultratrace level. Calibration has to begin with a
blank and at least one point lower than 0,1 ppb.
In order to maintain a good linearity of the calibration, we reduce the working range of the cell 0 to 1 ng.
The ultra-trace calibration has to be prepared as follow:
- Prepare fresh standard solutions according to the customer working range. It is recommended to only
use daily prepared standards in glass flask, perfectly cleaned. We suggest using a Standard Stock
solution with a concentration lower than 1000 ppm, such as 10 ppm, to avoid a lot of dilutions.
- Standards have to be stabilized with HCl (2% v/v), in order to avoid mercury evaporation. Use ultrapure
grade HCl.
- Always use 0.3 mL of standard. The use of 0.3 mL instead of 0.1 mL volume to enhance the data
reproducibility
- The first calibration point has to be a real blank with the same volume (0.3 mL) and matrix (water with
2% v/v of HCl) used for all the other points of the calibration. The ABS value of the first calibration point
must be less than 0,0040 in cell 0.
- Perform at least two replicates for each standard
- Calibrate up to 1 ng and then activate the Ultra-trace function
3. PRACTICAL EXAMPLE OF ULTRATRACE CALIBRATION
Below is reported an example of ultra-trace calibration. The target of this calibration is to provide a curve
suitable to analyze samples with a mercury level from 0.1 ppb.
In this specific example we have made 4 standards from 0.0125 ng up to 0.5 ng, each of them in triplicate
in order to show the reproducibility and the stability of the system at that range. We use 0.3 ml both for
standards and QC test. Once the last point of the calibration is done. Activate the Ultra-trace function.
These are the results we got:
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