Milk Calibration Standards


Milk Calibration Standards & Pilots / Daily Check Samples

LABTEK Services was established in 1987 and for over 25years we have been supporting the UK Dairy infra-red and photometric analyser.

In 2008 as a result of not being able to source accurate and reliable calibration samples for our engineers we decided to introduce our own and partnered Qlip (Netherlands)the largest accredited milk testing laboratory in Europe.

The Qlip Calibration sets have proven to be very popular with a number of national groups and worldwide recognised institutions now using the sets on a monthly basis.

Uniquely LABTEK Services can offer not only product support but also instrumentation support, and assist instrument users when guidance is required.

The QLIP Calibration & Pilot Samples are suitable for all Infra-red dairy Analysers including the Lactolyser, Lactoscope, Lactoscope FTIR ,Foss FT120, FOSS F1 & F2, FOSS Minor, Bentley Analysers


Understanding Calibration and Inter-correction of Infra-Red Instrumentation.

Many clients say we are only interested in the fat result. However on an Infra-red instrument the fat result is made up of a certain % of fat, a part % of protein and a part % of Lactose, these are known as the inter-corrections. Therefore if the protein and lactose are not calibrated correctly are you getting a true value of Fat %?

All infra-red instruments be they Foss Electric Milkoscan 50, FT120 or Delta Lactoscope will have left the factory having been calibrated on a wide range of fat, protein and lactose samples, however major parts may have been replaced or false calibrations due to inappropriate samples may have occurred.

A well calibrated infra-red instrument should have a slope close to 1.0 and a bias close to zero on all milk channels.

Unfortunately most commercially available calibration samples have very little range in their protein and lactose samples and this tends to confuse self-calibrating instruments.

Commercially Available Samples                         e.g. PROTEIN   3.30 – 3.60%      LACTOSE 4.45 – 4.75%

LABTEK  QLIP Samples                                      e.g. PROTEIN   2.00 – 5.00%      LACTOSE  2.97- 5.79%

Any instrument that has a slope of less than 0.75 and a bias greater than 0.75 either has a fault or is incorrectly calibrated. This is true for Fat, Protein & Lactose of any standard milk (i.e whole, semi or skim)

Unfortunately most commercially available calibration samples have very little range in their Protein & Lactose and this tends to confuse self calibrating instruments.

Commercially available Protein Samples 3.30-3.60%

If the commercially available samples were used in a calibration and all the samples above 3.4% had a -0.03 bias and all the samples below 3.4% had a bias of +0.03 then it would appear to be a good calibration since the + & – would cancel each other out and you would end up with a zero mean bias.

However a self calibrating instrument has to choose a best line of fit for these samples and we have seen on many occasions can actually end up with a bias of 3.50 and a slope of –0.05.

What would this mean to your results:-

If you analysed water the instrument would read 3.5%, if you analysed milk with a true protein of 3.5%, the instrument would read 3.50%.

Clearly something is not correct!

Now Print out the slope and bias’s of your instrument, are they showing slopes of less than 0.75 or bias greater than 0.75? if yes then you need a solution to your calibration techniques.

The Solution

LABTEK Milk Calibration Standards

Labtek Protein SamplesFAT RANGE                                          0.07 – 6.00 %

PROTEIN RANGE                                2.00 – 5.00 %

LACTOSE RANGE                              3.00 – 6.00 %

Protein Samples P1-P5

The graph shows a set of LABTEK Protein Samples notice how it extends the testing range compared to the graph of the commercially available samples. The slope through the true testing range of 3-4% is close to 1, therefore a sample of water analysed would be close to 0.00 and the true 3.5% Protein would read 3.5%

Product Code MCS7 : Milk Fat Calibration Samples* (7)

If fat is your only concern we have a seven sample set from skim to 6% in 1% steps these have protein and lactose results but not with extended ranges.

Product Code MCS17 : Milk Fat (7)/ Protein(5) / Lactose(5) Calibration Samples*

This set of 17 samples provides a comprehensive range of samples for the three major components of Milk. Examples of which are given below:-

Product Nos Fat % Product Nos Protein % Product Nos Lactose %
F0 0.07 P1 1.66 L1 2.97
F1 0.99 P2 2.57 L2 3.70
F2 1.97 P3 3.45 L3 4.40
F3 2.96 P4 4.34 L4 5.11
F4 3.96 P5 5.22 L5 5.79
F5 4.99
F6 6.01


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