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PFP7/REV C/01-08
4.4
Calibration: PFP7/C
When using the PFP7/C, a calibration curve is not required as the display is calibrated in direct
concentration units. Therefore only one top standard is required to enable this calibration to be
performed
.
Installation and set-up procedures should be carried out as for the standard Model PFP7.
NOTE:
The Model PFP7/C allows direct readout of Na and K concentration
in serum samples. Na levels in urine samples may also be read
directly from the display, although K levels in urine can only be
determined by plotting a calibration graph (refer to standard PFP7
calibration).
Samples of both serum and urine should be diluted 1 in 100 or 1 in
200 to obtain optimum results from the flame photometer.
To calibrate the unit for clinical use the following steps should be carried out:
1. Aspirate deionised water and set the display to read zero.
2. Select the appropriate element (Na or K) on the
filter select
control and the position of
the decimal point using the
d.p.
switch.
3. Aspirate the required standard, e.g. 140mmol/l Na, 5.0mmol/l K which has been pre-
diluted at least 1 in 100 and set the display reading accordingly using the
fine
and
coarse
sensitivity controls.
4. Adjust the
fuel
valve in a clockwise direction until a peak reading is obtained. Re-set the
display reading accordingly for the standard being aspirated.
NOTE:
There is a time delay between adjusting the flow of fuel and seeing
the effect of the adjustment. A pause of a few seconds is therefore
necessary between making every fine adjustment.
The optimum flame conditions are different for Na and K and
retuning is necessary when switching between elements.
5. Re-check the zero setting and adjust if necessary.
6. Aspirate the pre-diluted sample and note the reading.
7. Calibration needs to be checked periodically by aspirating the blank and standard
solutions. Initially this check should be carried out after every 10 samples. Experience
and increased confidence in the PFP7/C will enable you to best judge the frequency of
this check.
4.5
Shutdown
1. Aspirate deionised water for at least ten minutes.
2. If the shutdown is short term i.e. the instrument is to be used again the same day/shift, it
is adequate to remove electrical power from the unit by depressing the
power
switch.
This will safely extinguish the flame.
3. If the shutdown is longer term or if the laboratory is likely to be left unattended during
the shutdown, then the fuel supply should be turned off at source; wait for the
FLM
indicator to extinguish and then turn off the power. This ensures that there is no gas left
in the tubing to the unit.