5.4 Adding a standard addition
When prompted, a 20ppb Standard Addition needs to be added to the
SAB. This is achieved by using the pipette (which is set to 280µl). The
20ppb default setting can be changed prior to commencing analysis by using
the up/down selector in the Metaware, or during analysis by pushing the
joystick left and right when using the handheld instrument. Each 140µl
increase on the pipette is equivalent to 10ppb.
If the user wants to measure higher levels, then a higher value closer to the
concentration level will be required. The accuracy will increase the closer the
Standard Addition is to the actually concentration. For example, if an unknown
sample is expected to be around 15 ppb, then a 20 ppb standard in this case
is sufficient. If the user expects the analysis to be 100 ppb then, for example,
a 120 ppb standard would be suitable.
How to use a pipette
1. Place a clean pipette tip on the pipette.
2. Select the volume required by twisting the dial at the top of the pipette.
3. Hold the pipette vertically with the hand wrapped around it and the
thumb on the plunger and press the button down gently to the first stop.
4. Place the pipette tip in the standard bottle just underneath the top of the
liquid and slowly release the plunger.
5. Move the pipette to the SAB and locate the pipette tip through the hole in
the SAB.
6. Push the plunger all the way down to the second stop and hold, then
slowly withdraw the pipette tip from the SAB.
7. To release the pipette tip after use, push the white button at the side of
the pipette.
Before carrying out testing, become familiar using the pipette and the two
different stops on the plunger to ensure the correct volume of standard is added.
Metalyser® Field Pro HM3000 Instruction Manual v 5.0
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