Hello! I've measured particle size of o/w microemulsions, but the size of my every formulations are over 300 nm, although my formulations are clear, like water.
I use zetasizer zs90 of Malvern, no dilution.
Thanks
the particle size can be measure or analyse using Laser Particle Size Analyzer e.g BT-2003 -laser particle size analyser byBetter size Instruments Ltd. XRD data analysis can also help to identify crystallite size if the sample is cyrstalline in nature
Sikander Hayat thank you, sir. Can i use SEM instead? And if there is no crystalline, you think what is the reason?
Duyen Hoang
I assume you had an error message in the Quality Report. What did this say?
Please provide your report with the z-average and PDI. How did you filter your continuous phases? Are you reporting intensity or volume distributions?
I see you did not dilute your systems. The ZS 90 means that light has to pass through the cuvette and out again so that any contamination in the way (and dust contamination is the bane of intensity distributions). Are you sure that light can get in and out of the cuvette and is not attenuated out. What cuvettes are you using?
Alan F Rawle this is my result, sir. My microemulsion has a higher viscosity than water but I haven't measured it, I observe it. I use a plastic cuvette with four clear sides.
Duyen Hoang
Several things:
- You should use your local agent or distributor rather than relying on ResearchGate. I assume they sold the instrument and can provide local support in your local language
- Have you measured a standard latex (e.g. 60 or 100 nm) to confirm the instrument performance? If not, do this and eliminate the instrument from the equation
- The higher the viscosity of the continuous phase then the slower the particles move (Brownian motion). This is what the instrument measures. You have used the viscosity of water in the calculation and the result directly scales inversely with the viscosity. You need to measure the viscosity and input this into the parameters
- The attenuator is at position 11 (fully open) which tells me that there is little scattering in the system. You need at least one of three things working for you to have better scattering: larger size, higher concentration, bigger optical contrast (relative refractive index). Where are your particles?
- The report states 'Refer to quality report'. What does this say? You'll have clues there as to potential reasons and fixes (in Expert Advice). You can see these tabs in your screen dump
- The disposable cuvettes are not as good optical quality as the quartz. If your material was < 10 nm then I'd be looking to use the quartz cuvettes. However, I have successfully measured 6 nm material in the disposable cuvettes, so it's still easily possible
- Filtration is vital. How did you filter your water?
- The PDI shows a very wide particle size distribution range perhaps indicative of large material. What does the correlogram look like? Please provide this picture (you can see the correlogram tab in the menu). I suspect you do not have a clean exponential decay but rather the plot rises in the far field
There are 3 objectives of the measurement - stability, stability, and stability. You'll need to digest my points above and go and take 5 measurements in a row which over-plot and the z-average differing by no more than 5% RSD.