Sample tube cleanliness is extremely important for repeatability. Before use, tubes should be washed in warm water containing a suitable detergent, rinsed in clean water and thoroughly dried.
Always use the same amount of sample / standard. i.e. 2.5ml
Before running tests, gently wipe the probe, stir wire and mandrel with a clean tissue to remove any contaminants from prior tests. It may be necessary to dampen the tissue if contaminant is dried on, but remember to dry off afterwards. Be careful not to bend the probe and stir / freeze wire.
No special sample preparation is required apart from ensuring that raw milk is thoroughly mixed and the sample temperature is not too cold (i.e. <5oC) as this may cause the sample to pre-freeze.
Calibration standards should be gently inverted several times to ensure the contents are adequately mixed prior to use.
Perform a full calibration weekly. Check standards daily. If they are within +/- 2mc recalibration is not necessary. As a QC check it is advisable to analyse the 512moC standard every hour.