Hi Nicklos,

I understand that  you want  to prepare a stock solution (s.s.) concentration from the plant extract to be examined  by dilutions in  a final concentration with keeping the percent of DMSO  as 0.5%.  If that is the case, I will gave you a simple example: 

In the DPPH assay:

1- Calculate how many times will be your sample diluted at the final step of the assay?.  if you load 1 ul of sample s.s. into a well of 96-well plate. Then-after, 199 ul of DPPH solution was dispensed into the well. It means the sample s.s. was

1 ul and become now 200 ul (1+199). So the  Sample s.s was diluted 200 times = (200 folds) = dilution factor 200

2-Determine the concentration that you need to examine.

 I f you need to examine a sample concentration of 100 ug/ml as a final concentration. So you need to prepare your s.s. as 100ug/ml multiplied by the dilutoin factor 200 as indicated below. 

(100 x 200= 20,000 ug/ml. It is the same as 20 mg /ml DMSO .

 It is the same as 2 mg/100 ul DMSO.

It is not clear whether help is needed for the  extraction procedure or testing procedure.

It is not clear what you are asking. Do you want to make water and ethanol extracts of plant material and test the extracts for inhibition of something by adding the extracted material in DMSO at a final concentration of 0.5% (1:200 dilution in the assay)? If this is what you want to do, dry down the water or alcohol extracts by lyophilization, dissolve the dry material in 100% DMSO at 200 times the assay concentration, and add a volume of the 200X solution equal to 1/200 the final assay volume to the assay.

Hi Nicklos,

I understand that  you want  to prepare a stock solution (s.s.) concentration from the plant extract to be examined  by dilutions in  a final concentration with keeping the percent of DMSO  as 0.5%.  If that is the case, I will gave you a simple example: 

In the DPPH assay:

1- Calculate how many times will be your sample diluted at the final step of the assay?.  if you load 1 ul of sample s.s. into a well of 96-well plate. Then-after, 199 ul of DPPH solution was dispensed into the well. It means the sample s.s. was

1 ul and become now 200 ul (1+199). So the  Sample s.s was diluted 200 times = (200 folds) = dilution factor 200

2-Determine the concentration that you need to examine.

 I f you need to examine a sample concentration of 100 ug/ml as a final concentration. So you need to prepare your s.s. as 100ug/ml multiplied by the dilutoin factor 200 as indicated below. 

(100 x 200= 20,000 ug/ml. It is the same as 20 mg /ml DMSO .

 It is the same as 2 mg/100 ul DMSO.

So i want to dissolve powdered samples of the leaves into distilled water and ethanol. say 10g of leaves into 200ml water and ethanol each. Then filter and centrifuge. Then freeze dry the sample. If lets say i finish with a mass of 2.14g for the aqueous extract and 3.22g for the ethanolic extract. 

I need to now prepare my stock solution by redisolving these in distilled water, 0.5%DMSO and ethanol.

Can say for example that if i take 1g of the aqueous extract and dissolve in 20ml of water, can i say the stock concentration is 50mg/ml for the aqueous obtained by  (1g/20ml).

Can i then dissolve the aqueous stock in 0.5%DMSO?

If you dissolve 1 g of solid in 20 ml of solvent, it is indeed 50 mg/ml. Of course, it may not all dissolve, in which case the concentration will be less than 50 mg/ml.

If I understand correctly, you want to add DMSO to the aqueous solution so that the final DMSO concentration is 0.5%, or 1 part in 200 by volume. To a close approximation, you just need to add 5 microliters of DMSO to each ml of aqueous solution.

Thanks Adam B Shapiro. Your comment is very helpful

Hi Nicholas

Not sure if this will help you or not but please check them.

Best regards

The flavonols quercetin, myricetin, kaempferol, and galangin inhibit the net oxygen consumption by immune complex-stimulated human and rabbit neutrophils.

Figueiredo-Rinhel AS, Santos EO, Kabeya LM, Azzolini AE, Simões-Ambrosio LM, Lucisano-Valim YM.

Z Naturforsch C. 2014 Jul-Aug;69(7-8):346-56.

 Above all comments with Nicholas' questions are very helpful for my research too, since I also try to dissolve my plant crude extract which was obtained from maceration with 80% ethanol, it was difficult to dissolve in distilled water straightly. It cannot dissolve really, I can try above method and use the calculations too. Thank you everyone here.

Sir, how can we determine the concentration of extract?

Suppose 10gm of plant dry powder was extracted in 90 ml of 90% methanol. and then filtrate was rotatory evaporated and we got about 9 ml of extract from the filtrate. What would be the concentration of extract??

If you want to know the concentration of all solid material, dry down a specific volume of the extract in a weighed container and measure the additional weight from the solid material left behind after the solvent is removed.

1- First, a Beaker or a crucible should be brought, weighed (Assume that the weight is 100 g)

2- Transfer the extract to the Beaker

3- The solvent used in the extraction process shall be disposed of by evaporation of until the dry matter is obtained as far as possible

4- The beaker is weighed after full evaporation of the solvent (Assume that the weight is 110 gm)

5- The weight of the extract (the weight of the beaker with the extract - the weight of the empty beaker) = 110-100 = 10 g

6- The extract is dissolved in the appropriate solvent Ethyl alcohol is often used and an emulsifier may be added (the amount of the solvent is calculated to obtain the desired concentration(

To prepare different concentrations:

1- The extract is dissolved in the minimum amount of suitable solvent and then a quantitative transfer is done to a volumetric flask with a final size of 100 ml (the appropriate size for the quantity of the extract).

The concentration of the extract is calculated as follows

10gm/100ml = 10×103mg/100ml= 100 mg/ml

Different concentrations could be prepared from that stock solution

To prepare 5 mg / ml with a final volume of 100 ml

V1×C1 (before dilution) = V2×C2 (after dilution)( the concentration which we would to prepare )

? ×100 = 5×100

V1= 5×100/100= 5 ml

Take 5 ml of stock solution (Conc 100mg/ ml) and supplement with appropriate solvent to 100 ml in volumetric flask.

To prepare 0.5 mg / ml with a final volume of 100 ml

? ×100 = 5×100

V1= 0.5×100/100= 0.5 ml

Take 0.5 ml of stock solution (Conc 100mg/ ml) and supplement with appropriate solvent to 100 ml in volumetric flask.

In that case we use a DMSO 0.5% instead of the solvent