To prepare a concentration of 10 µg/ml, pipette out 10 µl of the drug in a test tube using a micropipette. Then dilute it with 990 µl (making a total volume of 1 ml) of the solvent (ethanol, methanol, water etc) you are going to use in your experiment. Similarly, do for 20 µg/ml. Pipette out 20 µl of the drug and then dilute it with 980 µl of the desired solvent and so on....

Dear Ashok,

It's simple. As you don't know the drug stock concentration (in liquid), directly weigh the liquid to make the stock solution (ex: weigh 5mg of liquid stock and dilute to 1ml to make 5mg/ml stock). From this stock, your working concentrations can be prepared by taking 2, 4, 6, 8,10ul of 5mg/ml and diluting them to 1ml will result in 10, 20, 30, 40, 50ug/ml solutions respectively.

Good Luck..!!!

Dear Golla,

If he weighs liquid stock, 5 mg accounts for the weight of solid drug as well as the liquid in which it is dissolved. If he wants exact 5 mg of drug in 1 ml, he cannot weigh directly the liquid. Just please think once again :-)

Dear Archit,

As he don't know the stock concentration, how can he weigh the drug. If I am not wrong, he can use the density (d=w/v) of that liquid to get the desired weight of that compound. Even if he don't know the density too, he can directly weigh the liquid which will cover both of its density and volume proportionally to get the weight of that compound dissolved. This will work nicely for his working stocks that to be prepared in ug/ml. If he wants work stocks in molar, then he has to consider the Mol.wt of that compound and accordingly the weight and volumes will vary. This is the way generally all do this type of basic calculations.

If you think this is not the correct way to prepare working stocks for him, you only can suggest some other batter way to solve his problem.

I think density method is the better one than weighing the liquid. If he knows the density, then he can calculate the weight in the liquid and then can proceed with the calculations.

Both are same Archit. If you consider the density of the liquid, required amount can be taken using equivalent liquid. Practically, this equivalent liquid can be directly obtained by weighing the liquid, which will also consider its density at working temp.

So, weighing of liquid directly will solve his problem. Please think once again about it..:-)

Dear Archit,

If i want to prepare a concentration of 10mg/ml, is it will be the same procedure as pipette out 10 µl of the drug in a test tube using a micropipette. Then dilute it with 990 µl (making a total volume of 1 ml) of the solvent (ethanol, methanol, water etc) you are going to use in your experiment as u mentioned early?

The drug comes with a known weight/volume of the active ingredient eg 10g of the A. ingredient.  From here, prepare the stock solution by weigh 10mg and add it to 1ml to make 10mg/ml. Then pipette 10µl and dissolve in 990µl to make 10µl/ml which is same as 10µg/ml. do same for other concentrations. I hope it helps

you must determine empirical form of antioxidant.

calculate molecular weight; choose element you want and calculate their ratio in the empirical form.

fellow the method shared to you for preparation concentration you need.

eg. Boric acid contain (16.5%boron), borax contain (11.3% boron) or SoluBor contain (20.5% boron).

The conversion factor between concentration of H3BO3 and other units is 5.72. This factor is determined by the ratio of atomic masses:

mH3BO3/mB = (3*1 + 10.81 + 3*16)/10.81 = 5.72

http://www.nuclear-power.net/glossary/boron-10/convertcalculator-boric-acid/

how do you prepare in terms of essential oils?

firstly for prepare micro gram/ml solution we make stock solution like-1 mg/ml. for 2 micro gram/ml, we take 10 micro litter from stock and than make up to 5ml which prepare 2 micro gram/ml solution. similarly all conc. we can prepare. 

if any drug is in solid form i.e. powder then, firstly we have to make its solution with desired solvent for exa distill water.

if we have to make 5 microgram per ml concentration of antibiotic /drug

in 100 ml stock solution (in distill water)

then first we have to convert microgram drug into milligram

5 micrograms/ml means 0.005 mg/ml

in 10ml distill water it is 0.05 mg/10ml

and for 100ml distill water it is 5 mg/100ml

for 1000ml distill water we can makeup with 50mg/1000ml

prepare stock solution according to your need and preserve it for further use.

I have the stock solution of 10mg/ml and I want to make the dilutions of 0.4, 0.2,0.1 and 0.05 from this stock solution. I don not know how to make it please help me. thanks

if I have lipopeptides extractions from bacteria I dissolve it with methanol. but I don't know the concentrations , know I want make different conc. from this liquid like 50,75,100,200,300 and 400millgram per ml . what should I do ?

Aishwarya Chauhan

my drug do not dissolve in DI water.

what should I do to dissolve it in water?

Should I dissolve it in organic solvent , first, for further dilution in water?

In orgnic solvents which one is more appropriate to use, methanol, ethanol or acetone?

There is simple equation to make new concentrations from stock solution:

s1*v1=s2*v2,

where, s1=conc. of stock solution (known, e.g: 5ppm)

v1= vol. need to take from stock solution (unknown)

s2= conc. of new solution want to prepare (e.g., 2ppm)

v2=vol of solution want to prepare (e.g. 50ml)

Rida Shakir dissolved your drug in DMSO.

By dissolving the crude extract solutions in DMSO.

I have prepared 0.5 McFarland standard and measured its OD at 625nm and found it to be 0.124.What can i do to reduce the OD to 0.10?

I have 1mg/ml solution sample then how to nake it microgram/ml solution for antioxidant dpph assay?

Dissolve 1microgram in to 999 microgram so it will be formed

Dilute your drug soln and take 10microliter pipette and fix it with micropipette and take your drug soln and add 990 microgram solvent so it become 10 microgramperml