I use emulsification-diffusion method to prepare PLA nanoparticles, but when I pass the sample to the equipment, this text appears:"Result: refer to quality report", and it says that the sample is low concentration or high concentration or is too polidisperse.
I have diluted my sample, but it comes back with the same result.
this is one of the common problem during particle size analysis.
you have to be very critical about concentration. you take some trials and fix the dilution ratio. I generally use 0.1 ml : 10 ml approx. sometimes this problem arise due to aggregation also. for that i suggest you to Sonicate the sample for some time before analysis. Always use good quality water for dilution.
if u disperse freeze dried powder then again concentration and aggregation is important.
what is your PDI value??
At the begginig it was PDI=1, but I increased the concentration of emulsifier agent to 1 %w/w, and I got PDI=0.4
Thank you so much for your help.. I will try to do all those rhings.. ;)
Check if your sample has a natural adhesion (agglomeration) tendency. Those samples which agglomerate often show such oscillations in PDI too. This can be checked by seeing a sudden drop of average particle size as the number of runs goes up in the same sample and in a single measurement. In general, I also would recommend you to use the link as follows to help your concentration optimization. Good luck. http://www.malvern.com/common/concentration_calc/concentration_calc.htm
Dear Tatiana,
assume you solved your problem in between. In more general 2 points:
First I would contact Malvern Support, likely they will be happy to assist. At the end it might have be a problem with a faulty instrument.
I would never change the system significantly to get an instrument to 'show good results'.
It is the sample as is, what you want to have information about, not simply any data which look fine.
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