How to measure dry mass?

[l0sthart]

How to measure dry mass? is there any equation or so? Hope to get a reply soon. Thanks (:

[canalon]

No equation. One simple experimental procedure:
take sample put in the oven/desiccator until totally dehydrated and weigh. That simple.

[Cristgonz]

canalon is right.
you don't need an equation.
just weigh it and then put it into a "furnace" and then weigh it again (you could know your water and dry mass weight).

[MichaelXY]

All bets are off if you try this on the moon however

[canalon]

Not really. If you use a balance calibrated to measure the actual weight in the moon gravity field, it will give you the exact same answer. Why wouldn't it. Just use properly calibrated instruments. That is what Quality control is used for

[MichaelXY]

Yes I realize this, my point was that gravity plays a role in weight.

[MrMistery]

or simply measure with the same instrument and multiply by six.

[canalon]

or simply measure with the same instrument and multiply by six.

Calibration can often be just that

[Cristgonz]

go to the moon and measure haha.
Canalon is right again, just a well calibrated instrument and wuala.

[hsoroosh]

I need to measure micro algae dry mass. I'm looking for a way measure it indirectly by spectrophotometer (absorbance) simply. is it possible? immediate reply needed! I mean if there is a way I can find an equation to figure out algae dry mass by the solution/culture/chlorophyll/etc absorbance in a certain wavelength.

Thank you

[canalon]

Easy... Or maybe not.
Find a relaible measure of the density of your culture for your algae. It does not matter what you are using, as long as you can confidently say that there is a relationship between your measured parameter and the cell density of your culture. And check that it works (do dilutions and count).
Once you have that measure the relationship between your cell density and the dry mass: i.e. measure the dry masss of the samples that you have used in the calibration of the step above. Redo a few times independantly to make sure that it works nicely.

Congrats you have your conversion parameters. Enjoy.

[hsoroosh]

Thank for quick reply
So if I understood truly, I can make a chart with different absorbance and their respective dry mass. and there should be a linear correlation between dry mass-abs . what wavelength you recommend me for that? is 680nm ok? would you please any scientific literature which I can refer to in my writing and references?

Thank you very much