Milestone Srl MA213-003 – DMA-80 EVO – User Manual
145
To prepare 100µg/Kg(100ppb) working standard, take 2mL of the 5ppm solution and dilute up to 100 mL.
To prepare 200µg/Kg (200ppb) working standard, take 4mL of the 5ppm solution and dilute up to 100mL.
To prepare 500µg/Kg(150ppb) working standard, take 5mL of the 10ppm solution and dilute up to 100
mL.
There are three standard different working range responses that the instrument may be calibrated on:
- The low range is 0- 10 ng Hg
- The medium range is 10-20 ng Hg
- The high range is 20-1000 ng Hg.
The working standards solution must be freshly prepared before every calibration.
8.2.2 How to store a liquid standard solution
Make sure the stock standard is not old or contaminated. As soon as the working standards are prepared,
transfer them into brown glass bottles. Aqueous standards with low Hg concentration are very unstable
when stored in plastic or regular clear bottles. Do not expose the Hg standards to the air.
Mix the aqueous samples each time prior to the analysis. As soon as the sample is pipetted out, close the
storage container.
Do not leave the solution bottles open on the bench and at the end store them into a fridge at 5-10°C
8.2.3 How to store standard reference materials
Standard reference material must be stored in its original tightly sealed bottle away from sunlight, humidity,
and intense sources of radiation. Before each use, the standard should be thoroughly mixed by rotating the
bottle before sampling.
If the determined value of the QC solution differs from the specs of known value, the standard could be
discarded. The value may differ if the catalyst is exhausted.
8.3 BLANKS
8.3.1 How to get good blanks
Good blanks are obtained using dedicated quartz boats, a good carrier gas and good conditions of each
component and environment where the unit is installed: the replacement of one or more components or old
components could impact blank values. Fork, catalyst, amalgamator, etc… must be cleaned and
conditioned, if new, or replaced, whenever the required instrumental blank value is not achieved.
Indicatively, the instrumental blank is considered good if the absorbance value is
- < or = to 0,0030 in cell 1 for most of applications
- < or = to 0,0015 in cell 0 when working at low Hg levels (ultratrace)
These values are intended for empty boats, running Standard Method without any sample or standard.
Acceptable blank value depends on the minimum value to quantify.
To Next Page
Loading...
