Do you have an analytical balance available? Some of these can read out to 0.0001 or even 0.00001 g. You could weigh out as little as 1 mg to a precision of 10% or 1%, respectively (increase the amount weighed to increase the precision). Do this in a small glass vial that has been tared on the balance. Then add 1 or 2 ml of a low-volatility solvent using a volumetric pipette or adjustable pipettor. Pipettors such as the 1-ml Rainin Pipetman can deliver volumes with a precision of well under 1% when properly calibrated.

If you are dissolving a large amount of solid in a small amount of liquid, you will have to take into account that the solid takes up some volume, which means adding a smaller volume of liquid than the desired final volume of the solution, then measuring the volume after the solid dissolves, and adding more solvent to reach the final desired volume.

HI

YES YOU CAN USE 10 ml or 20 ml pipette to measure the liquid or solvent. it will be accurate.  

Do you have an analytical balance available? Some of these can read out to 0.0001 or even 0.00001 g. You could weigh out as little as 1 mg to a precision of 10% or 1%, respectively (increase the amount weighed to increase the precision). Do this in a small glass vial that has been tared on the balance. Then add 1 or 2 ml of a low-volatility solvent using a volumetric pipette or adjustable pipettor. Pipettors such as the 1-ml Rainin Pipetman can deliver volumes with a precision of well under 1% when properly calibrated.

If you are dissolving a large amount of solid in a small amount of liquid, you will have to take into account that the solid takes up some volume, which means adding a smaller volume of liquid than the desired final volume of the solution, then measuring the volume after the solid dissolves, and adding more solvent to reach the final desired volume.

Dear chee ping Tan,

In addition to the excellent answer of Dr Shapiro, I would like to add that you can also use the analytical balance to add the solvent to your solid in the same vessel. Since every solvent has its own specific density, you will have to calculate the desired weight for the corresponding volume.  The advantage is that you can adjust the volume of your solvent to the amount of solid that is actually deposited in your vessel. This is particularly handy in case of clumpy materials, eg after recuperation from a evaporation bottle.If you take out a sample of say 10ul with a calibrated pipette, you can directly read back what weight was taken and correct for volumetric effects, if needed. Kind regards, Harrie Verhoeven

Thank you all for the your answers. Actually I still have another question that bother me for quite some time. 

Considering this: .

1. I need to prepare a 5 ml, 40% sodium salicylate solution from powder. Let's said we used a 5 ml Eppendorf bullet tubes and ddH20 as solvent. 

2. The tubes will be placed inside a small beaker, place on the balance, and tared. Then, 2 g of sodium salicylate is accurately weighted into the tubes. 

3. As mentioned by Sir Shapiro, every substance has it own density, and chemical occupied volume.

Scenario 1: I then pipetted exactly 5 ml of liquid into the tubes with a serological pipette. But the final volume would exceed 5 ml after the chemical is fully dissolved.

Scenario 2: I continue to use the balance (without taring), to weight the ddH2O I added to a final weight of 5.0000 g, but is this scientifically correct? I mean this is a mixture of sodium salicylate and ddH2O, it is not right to assume that the density remains as 1 g/cm3 and thus weighing become another issue again? 

I hope you all understand what I mean and I do apologize if I have any misunderstanding in the principle of chemical preparation. All feedback and comments are welcome. 

Thanks. 

Hi Chee Ping Tan

I assume this 40% solution means 40% weight per volume, so you want 2g of powder dissolved in a final volume of 5mL. If not, then ignore what I say below.

Weighing the 2mL of powder shouldn't be too difficult. You can use a weigh boat on a mass analytical scale and then transfer the contents with some squirts of ddH2O into a scintillation vial or eppendorf tube.

What you should do next is to do a quick test of volume. As you said, dissolving the powder alters the final volume, so adding a full 5mL of ddH2O is inadvisable, you'd overshoot the mark. Try adding 2.5mL or 3mL of ddH2O to the powder first. Dissolve the powder as best you can and then pour this mixture into a 5 or 10mL measuring cylinder. If there is anything leftover, Use an eppendorf 250 mL/ pippette to remove as much of the solution as you can from the original vial into this measuring cylinder. Then slowly use the pipette to add volume of ddH2O so that the solution reaches the 5mL mark, and then transfer all of this back into the scintilliation vial/eppendorf vial. This would be 2g in 5mL solution.

You can use the test of volume to adjust how much water you wish to add for future solutions. For example if you first add 2.5 mL of ddH2O and find that when you pour the solution into a measuring cylinder, it is 4mL, you know you could add more ddH2O initially. When you find the right volume, it is possible to bypass the measuring cylinder step by just pipetting the required volume of ddH2O directly into the Eppendorf tubes. Either way as long as you dissolve the powder fully and don't overshoot the 5mL mark to start with, it should be fine.

Na salicylate is not an expensive reagent so why not do the experiment, e.g. in a 10 mL measuring cylinder on a balance,  First calibrate the cylinder at say 5 mL using water.  Now add the salicylate and add water until the volume, dissolving as you go, until the volume reaches exactly 5 mL  based on the previous calibration. If there is a temp change allow the temp to equilibrate befor making the final volume adjustment.

and weigh in the water  

Thank you to Dr. Wong and Dr. Milham. 

I will take your advice into practice.

Also thank you to other researchers who answered my question, you all have been very helpful .