As mentioned in my first blog “A day in the life of a Helpdesk Specialist” in December, I promised to post regularly on the most Frequently Asked Questions we receive in the Support Team. So with that in mind, we will start with –
Why are my results out of specification? (Laser Diffraction / Mastersizer series)
This is one of the questions we get asked most often – why are my results out of specification? Everything was fine yesterday/last week/last month…
There can be several reasons – there are some things you can check before suspecting an instrument issue.
1. Look at everything leading up to the measurement – has anything changed regarding your sample (does it look the same? flow the same? is it the same color!?)
Has anything changed regarding your sampling? Are you getting a representative sample from the master batch to the accessory? Are any and all pre-measurement steps being taken – do you make up a slurry, or use any other pre-dispersion aids (surfactants, ultrasound?)
If you’re happy the sampling (or sample!) hasn’t changed, then move on…
2. Look at the measurement settings – is the sample handling unit set up in the same way?
Check air pressure, vibration/feed rate for dry measurement, pump/stirrer speed and ultrasound for wet – and are your analysis settings correct for this product?
If you are able to lock all of this down in an SOP (Malvern’s Standard Operating Procedure file) then it is a good idea to do so!
If you aren’t sure of the correct settings, you can usually extract them from a historical, good record (right-click and extract SOP);
Once you’re definitely analyzing the data in the same way, it’s time to check…
3 – Look at the system cleanliness – does the background look the same as it always did? Is there any left over sample, is the reported laser power down on its previous level? A good background is shown below.
While you are checking the background, could anything have happened to your water quality? This can easily affect how the sample behaves when it is in the dispersion unit.
Happy with the cleanliness and water quality? Then it’s time to consider…
4 – Look at any displayed messages – Could this be a real instrument issue?
Are you getting any error or warning messages? Most of the time, an error message gives us a good idea of the cause of the issue – grab a screenshot and email it to the helpdesk, and feel free to follow up with a phone call.
If the steps above don’t get you back on track, then…
It’s time to contact the Malvern Helpdesk
If you can supply some recent and historical data for us to compare, along with your instrument serial number, we can get on the case quickly and most likely get to the root cause within a few emails or phone calls. Remember – we are here to help!