Over the last 20 years I came across several incidents where one of our customers decided to test a sample normally as a favour for another department , a friend or external company. Like that one advert says "what can go wrong" ?
It all depends on the instrument and the nature of the sample. In the case of laser diffraction for instance we disperse a sample typically in a liquid. In most cases this would be water. Clearly testing a water-soluble sample would then not be possible. The next step would be to use a suitable organic disperant say iso-propanol. What can go wrong? Like in most situations, nothing will provided you are trained to swap between water and an organic dispersant. in the case of one lab their mission critical QC instrument went off-line for days because of such a favour. In our own lab we do this routinely with no impact on our instrumentation, but we are trained and have a lot of practise to do such a swap-out routinely. Even "experts" can be caught out. I tested a sample in canola oil and confidently cleaned the dispersion unit and flow cell afterwards to use with water etc.... Months later I was still removing trace amounts of oil ! Needless to say, I will not test samples in canolla oil again.
In the case of an portable oil particle counter it is physically possible to test water for instance or even diesel. In the case of water it will emulsify with the previous oil or organic flushing liquid and the flow path can permanantly become contaminated wih trace amounts of water - rendering the instrument useless. Diesel is less drastic and will simply generate misleading results as the viscosity is to low for a standard portable oil counter (bubles form in the flow path during measurement).
That is the reason why manufacturers like Pamas designed dedicated particle counters for water, diesel or oil. Alternativly they have flagship instruments like the SBSS that is designed to cope with a wide range of liquids.
On a more scientific note most instruments, in QC enviroments especially, is set-up specifically for dedicated material(s). It is risky to measure unknown samples as an inapproiate instrument settings could generate misleading results.
If you are in charge of an instrument keep these risks in mind ,or simply This email address is being protected from spambots. You need JavaScript enabled to view it. first that it will be safe to test this new sample material.