Keison PFP7, Руководство по эксплуатации и обслуживанию, Страница: 14 / 46

13 PFP7/REV C/01-08
1000ppm Ca, then Na analysis can only be achieved by removing the Ca with
oxalate/oxalic acid or ensuring all standards contain 1000ppm Ca.
4. Always try to follow a well-documented analytical procedure, which should contain
information pertaining to interference removal when applicable.
5. Standards and samples should not be exposed to the atmosphere for long periods due
to contamination from airborne particles and the evaporation of the solvent that could
lead to elevated concentrations.
6. When in doubt about the equipment or application, the operator should contact Jenway
for advice.
3.2.1 Sample extraction
A number of methods for extracting sodium, potassium, lithium, calcium and barium from a wide
variety of raw materials may be obtained by contacting the technical support helpline at
support@jenway.com.
The sample must be in the form of an aqueous solution, with no solid matter present, to be
suitable for direct introduction into the flame photometer. This is achieved by:
•
Extracting the salts from solid samples using deionised water or suitable extractants
e.g. saturated CaSO
4
for sodium in soil. Extraction is more successful using a blender,
macerator or shaking machine.
•
If the sample is organic then the organic material should be removed by ashing. The
remaining oxides are then dissolved using strong acids.
•
Filtration/centrifugation is used to remove solid debris.
When aqueous, the sample can then be diluted to a known, accurately measured volume using
deionised water. If it is a concentrated sample then the dilution ratio should be increased. If the
sample concentration is low then a small volume of diluent and initial extractant should be used.
Whichever method of extraction is used, the resultant solution must always be free of any
particulate matter that may cause blockages in the nebuliser capillary tube.
3.3 Dilution
In order to obtain samples and standards of the right concentration for aspiration into the flame,
various levels of dilution will often be necessary. Good quality deionised water should normally
be used for carrying out these dilutions and it is recommended that the same batch of water
should be used for diluting the samples and standards. More information on typical dilution
ratios is given in Section 4.3.