Tip: with small masses, adjust volume rather than mass when making a solution

Summary

In this video, The Bumbling Biochemist provides valuable tips for making solutions from small masses of solid substances. When the required amount is too tiny to weigh accurately, it's more practical to weigh at least the necessary amount, even if it's not exact, and then adjust the volume to achieve the desired concentration. The biochemist shares their personal method for handling small samples and ensuring minimal loss during the weighing process. Additionally, practical calculations are explained for determining how much liquid to add to achieve a specific concentration. This approach not only simplifies the preparation process but also minimizes errors inherent in measuring tiny amounts.

Highlights

• Use a larger-than-needed mass to simplify solution preparation. 📦
• Weigh directly in the container to minimize transfer loss. 🧪
• Calculate volume adjustments intuitively for desired concentrations. 🧮
• Use simplicity to avoid errors in tiny mass measurements. ⚠️

Key Takeaways

• When dealing with tiny amounts, weigh more than needed and adjust volume instead! ⚖️
• Avoid trying to weigh exact minuscule amounts; adjust your solution by volume instead. 📏
• Practical tip: Weigh directly in the tube to avoid transfer loss. 🚫🔄

Overview

Making solutions from very small masses can be tricky, especially when the substance barely registers on your scale! The Bumbling Biochemist has a solution: weigh a larger amount than necessary. This simple trick saves a lot of headache as it avoids the inaccuracies of trying to measure out a minuscule amount exactly! Instead, adjust the final volume to reach your concentration target. It’s an easy, effective method that ensures you get the job done without unnecessary frustration.

In the lab, it's important to minimize any potential loss of your material during the weighing process. Our biochemist recommends weighing directly into the container you'll use for your solution. By doing this, you’re dodging the common pitfall of losing precious micrograms transferring from one container to another. Smart and efficient!

Finally, when you’ve got your weight and target concentration in sight, calculate the amount of liquid needed to hit your concentration goal. Even if you’re working with not-so-precise equipment, this method ensures you're close enough for comfort! It makes the process intuitive and allows you to work with what you have without stressing over microscopic errors.

Tip: with small masses, adjust volume rather than mass when making a solution Transcription

• 00:00 - 00:30 when you're trying to make a solution from a solid and it would be a really really tiny amount that you would need to weigh out often the simplest thing to do is to weigh out an amount that is at least what you need um but not exact and then adjust the volume so that you get the final concentration that you want basically you have some sort of desired concentration you're going to need to get it into a weight over volume so if you're going from marity um then you just are going to multiply by the
• 00:30 - 01:00 molecular weight and that'll give you grams per liter which is the same as migs per male or if you start with BS per M great if you're going grams with liters that would be well if their point is that we're measuring really tiny amounts I doubt you're doing grams with liters but the same thing you'd stop there though so let's say I want know I want to make a five mes per Mill solution of BSA so Bine serum albumin which I'm using as kind of just like a gener filler protein in my solution to
• 01:00 - 01:30 help make my protein happy so it's not alone basically I only need 100 microl of this five migs per Mill because I'm going to dilute it to like 0.1 migs per Mill so if I go and say okay well how much do I actually need to weigh a BSA how much of the solid powder do I need so I do five migs per mil times .1 MLS because remember 0.1 Ms equals 1,00 micro 100 microliters man um yeah so basically you just a decimal point 1 2
• 01:30 - 02:00 3.1 MLS so now my Mills cross out I oh man I love Crossing things out and I missed a cross out okay so that will give me .5 migs which is way way way too tiny it won't even be measured on the scale that I'm using and so I say okay so it's not like BSA is that expensive or anything but I don't want to make way more than I need so maybe I'll make like a mill which would be about five migs so if I were to weigh out five IGS well
• 02:00 - 02:30 then it would be a mill but I know that it's really really hard to weigh out that tiny of a of a amount so instead what I do is I come and I weigh out about five migs I know that I want kind I need at least five migs if I've got at least .5 migs I'm good um but because like little tiny errors in the scale isn't that correct and if a little flake drops off let's go with at least five Megs so what I do is I put a little EP andorf on a little foam thing in the in there and I actually do the weighing in
• 02:30 - 03:00 there because that way I don't have to worry about any loss in transfer so I'm weighing it in the tube itself so that then I can just add the liquid to the tube and so my main constraint is making sure that I don't have more than what the tube can hold so this tube holds um 2 MLS so I just need to make sure I'm below 2 MLS which would be below 10 Megs so I weigh out and I'm at 9 migs and yes if I wanted to be super duper exact I would use a um more precise scale which would go out to more
• 03:00 - 03:30 digits um but here using what I can and I don't really care too much about the exact exact concentration so I weigh out nine migs now how much liquid do I need to get add in order to get to that final 5 migs per mil I wanted well we can think a little intuitively we know that it should be more than 1 mil and less than 2 Ms and it'll be probably be close to 2 Ms because 0.9 and um two I mean n and one
• 03:30 - 04:00 are or yeah n and 10 sorry oh nine and 10 are pretty similar I'm sorry it's been a long day so 9 and 10 are pretty similar we know that 10 would be 2 Ms we've got nine um and so we're going to be close to 2 Ms but a little under thankfully because our tube would only hold two Ms okay so how much harder though so we take our we're going back to this part where we have our weight per mil over Ms equals migs per our desired migs per liter so X is going to be the our volume
• 04:00 - 04:30 of the solution that we're going to make add um to give us that weight per oh divide it um to give us that final concentration and migs per M and so we just are going to take what we weighed and divide it by um the desired migs per M so we have nine migs over what Mills equals 5 migs over 1 mil we just multiply by X divide that flips cross cross you're left with 9 over5 Ms which is equal to 1.8 m so I can go and I can
• 04:30 - 05:00 add 1.8 MLS of my buffer my water whatever I want to add to dissolve my liquid in um and then I'll get the concentration that I want so again if you are going from a MIG perill already then you just need to take what you weighed and divide it by the desired so this was the desired so Wade over desired Maks Peril if you have to go from the marity
• 05:00 - 05:30 well now you've got to start by converting that marity to Gams per to your Ms per M or to your mil gam per liter which is the same as migs per Mill um and then you can go ahead and do this accordingly so it's a lot easier to just kind of weigh what you can um rather than trying to get exactly exactly the tiny little amount um especially because you're likely to kind of lose more in the process so hope that helped um and yeah so it's just one of those lab
• 05:30 - 06:00 calculation things that just kind of comes with time