7.2 Variable volume standard additions.
The standard addition added to the sample must be a concentration of the metal
that matches what is programmed into the instrument. The default set-up is to use
280µl addition of a 5ppm standard which equates to 20ppb in the SAB where the
SAB holds 70ml of sample.
To calculate the final concentration of standard in the SAB in ppb, use the equation
Addition volume (µl)
X Standard Concentration (ppm)
SAB volume (ml)
To achieve higher accuracy, the standard addition should be matched closely to
the expected sample concentration. For higher concentrations the volume of the
addition could be excessive, leading to errors due to the increase in volume of the
SAB especially with multiple additions. To reduce the volume smaller additions
can be made using higher concentration of the standards. If the standard addition
is changed the final concentration in the SAB needs to be calculated and entered
into the Solution increment box under Measurement options in the control panel.
The following table gives some guidance as to what values to use:
concentration
in SAB
standard
Addition
volume
*Standards supplied as accessories.
Metalyser® Field Pro HM3000 Instruction Manual v 5.0
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