sample prep for viscosity testing

[bdhedhy19]

Hi!
i need the help in testing viscosity of organic sample.. vendor C of A shows 5% solution with viscosity results of 750cPs using spindle 3 @ 30rpm and @ 80 Farenheit.
I weighed 15 gram of sample dissolved in 300 ml of water and heated to 100C brought back temperature to 80F and i check the viscosity, it was OOS.(very high)...

I wonder if i weigh 15 gram of sample and than wet the sample with 10 ml 80% TBA and add warmed DI H2O (40C) and let it stir in control water bath at 40C for 1 hour, lower the temperature to 26.7C and after half an hour, check the viscosity... It should be OK, right??? please let me know if this is right or if you have any different idea
thanks a bunch

[paulw]

When trying to replicate the result from a vendor for any assay which involved a preparation such as a 5% solution, I would ask for their method. If you bought the material from them, they will be glad to provide it.

I would not just randomly add another solvent in the hopes that it might thin the final solution. That's cheating. I am not familiar with this product in particular, but there is a chance that heating it much past the target temperature could have an adverse affect. With that level viscosity, I suspect the spindle 3 @ 30 rpm references a Brookfield LV viscometer, however for some reason they may even be using an RV viscometer so the spindles might be different. Again, their method would provide confirmation for you.

Going in blind, I would weigh 285 grams of water, weigh out 15 grams of the material, and then slowly add the material to the water with stirring. In the case of a thickening agent, I do mean very slowly, as I have found that if you just dump the lump sum in you'll get a mass that won't go into solution no matter what. After the mixture was homogenous, I would then put in an 80F water bath and bring to temperature. After it arrived at 80F I would test the viscosity.

[Andy F]

When trying to replicate the result from a vendor for any assay which involved a preparation such as a 5% solution, I would ask for their method. If you bought the material from them, they will be glad to provide it.

I would not just randomly add another solvent in the hopes that it might thin the final solution. That's cheating. I am not familiar with this product in particular, but there is a chance that heating it much past the target temperature could have an adverse affect. With that level viscosity, I suspect the spindle 3 @ 30 rpm references a Brookfield LV viscometer, however for some reason they may even be using an RV viscometer so the spindles might be different. Again, their method would provide confirmation for you.

Going in blind, I would weigh 285 grams of water, weigh out 15 grams of the material, and then slowly add the material to the water with stirring. In the case of a thickening agent, I do mean very slowly, as I have found that if you just dump the lump sum in you'll get a mass that won't go into solution no matter what. After the mixture was homogenous, I would then put in an 80F water bath and bring to temperature. After it arrived at 80F I would test the viscosity.

Just to add if you Google some products the addition occurs around 65°C rather than 40°C so you might want to try that.

[bdhedhy19]

Thanks Andy and Paul for your help ....
I called the vendor and they provide me their sample preparation and viscosity testing by kinetic method with an old fashioned viscometer (glass tube kind)
I used their sample preparation method (5% solution), No addition of 80% TBA required, sample dissolution turn out to be newtonian (clear) without any gluey or gel thing,than brought the temperature back to 27C checked the viscosity with Brooksfield LV viscometer using spindle 3@ 30 rpm.......It works great.
Thanks a bunch
have a nice weekend:)