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Serial dilutions are a valuable tool in biochemistry for creating a range of concentrations from a single sample, especially helpful for creating standard curves. The process involves stepwise dilutions where each step uses the output from the prior one. By applying the formula C1V1 = C2V2, biochemists can calculate concentrations across steps without computing each individually. Larger dilution factors cover a broader range, while smaller factors offer finer resolution within an expected range. Standard curves require serial dilutions to create reliable data points for analysis. Moreover, serial dilutions minimize errors by avoiding small volume transfers, offering precision and efficiency, particularly in generating solutions from concentrated stocks.

- Serial dilutions are like a biochemical magic trick for concentration control! 🎩✨
- Dilution factors dictate the scale of concentration differences in each step. 📏
- The formula C1V1 = C2V2 is your cheat sheet for managing serial dilutions. 📄
- Efficiently covers a wide or narrow range based on your dilution factor needs. 🎯
- Avoids pipetting inaccuracies by preventing tiny volume errors. 💧
- Especially useful for generating standard curves in biochemical assays. 📊

- Serial dilutions help create varying concentrations efficiently! 🧪
- Each step of a serial dilution uses output from the previous step, ensuring accuracy. 🔄
- Use the C1V1 = C2V2 formula for easy calculations without recalculations at each step! 🔍
- Larger dilution factors cover broader ranges, smaller ones offer finer details! 📐
- Perfect for creating standard curves and minimizing pipetting errors! ✔️

Serial dilutions are an ingenious strategy in the biochemist's toolkit when you need to create a series of concentrations that span a broad range. Imagine this as a way to step down a hill, where each stride is intentionally measured to halve what's in your nugget pouch. Much like spooning out Cheerios, you dilute systematically to achieve a desired concentration, using the output from the previous step as your new input.

The mathematical magic behind serial dilutions is the C1V1 = C2V2 formula, a trusty companion for calculating concentrations without the hassle of singular calculations at every stage. Larger dilution factors expand your view across vast ranges, while smaller factors refine the details. It's a dance of precision—where knowing your initial concentration and desired dilution factor lets you orchestrate the rest effortlessly.

Creating standard curves becomes a breeze with serial dilutions, allowing you to establish reliable data points for biochemical assays. By minimizing pipetting errors through stepwise transitions, you avoid the pitfalls of tiny volume miscalculations. This method’s adaptability shines in customizing solutions, transforming concentrated stocks into research-ready mediums without a drop of sweat.

**00:00 - 00:30**could a Serial dilution Be Your solution it could be if the problem is you need a series of concentrations that span a large range such as if you're making a standard curve let me explain zero dilution is a series of stepwise or I guess in this case spoon-wise dilutions where each time you're diluting something by some constant Factor this dilution factor or DF and what's distinct about a Serial dilution is that the output from one**00:30 - 01:00**dilution becomes the input for the next so for example if you take 12 you have 12 Cheerios per Spoonful and you mix that with a spoonful of milk now you get a solution that has six Cheerios per Spoonful and if you took a spoonful of that solution and mix it with another spoonful of milk well now you're gonna have three cherries per Spoonful and you could keep doing this over and over each time in this case you would be dividing by a factor of two you'd have a dilution factor of two if you're halfing things**01:00 - 01:30**each time you could also have a different um but be diluting things by a different dilution factor so if you age time you are getting a third of what you had before this would mean you've had a dilution factor of three and if each time you were had a fourth um so you were half you were quartering things each time well that would mean that your dilution factor would be four what happens in each of these cases is that the end concentration for one of your dilutions becomes the start**01:30 - 02:00**concentration for the next dilution and we actually have an equation that we can use to talk about initial and final concentrations we use this formula c1v1 equals C2 V2 the initial concentration times the initial volume equals the final concentration times the final volume sometimes this is also written M1 D1 equals M2 V2 where n stands for molarity which is the common unit of concentration we use in Biochemistry but this could also be any other**02:00 - 02:30**concentration including Cheerios per Spoonful you just have to make sure that it's the same on each side and this formula is super duper super duper helpful so many times in the lab and when you're doing a Serial dilution the C1 from one dilution is going to be the C2 from the previous dilution and so you could keep doing this over and over and you keep getting your beat your C2 from the 1 becomes the C1 of the next**02:30 - 03:00**one and then that becomes the C2 from that becomes a C1 of the next one and over and over and over so if we know the concentration of one of these tubes we can easily figure out the concentration of the next tube by taking C2 from that first one um and that'll be our C1 but now our volume is going to be twice what it was with the when you had the V1 that you're entering so you would have this concentration times the like one**03:00 - 03:30**spoonful volume but then your final volume would be two spoonfuls so that would be twice um and then you find your final concentration which would end up being half of what it was here and this is again for the dilution factor of two but there's a shortcut you don't have to know calculate each concentration at each of these steps in order to find the concentration at any one of these instead all you need to know is the initial initial concentration as well as**03:30 - 04:00**your dilution factor and when you know this basically what you can do is you can multiply that initial initial concentration by one divided by the um by the dilution factor raised to the number of dilutions to get the concentration of that specific dilution that to what's in that tube um so just let me explain through an example let's go back to our Cheerios our initial initial concentration was 12 Cheerios per Spoonful and then we so**04:00 - 04:30**that would be our C1 and then each time we're diluting it by two we have a dilution factor of two so our first dilution is going to be the second two this is because this was our initial tube this wasn't diluted this is going to be diluted so this is our first dilution and so we're going to raise things to a power of one and when you raise things to a power of one well they don't change and so in this case what we have is we have our C1 we have 12 and we're going to multiply it by one half to the first**04:30 - 05:00**and so this is just going to be 12 times one-half so 12 divided by two is six and so we see we have six Cheerios per spoonful now what if we go to the second dilution well here we have the C1 the same C1 so 12 and we're diluting it by 1 over 2 squared so times 1 4. so 12 times 1 4 is the same as 12 divided by 4 which is going to give us 3. and so we figure out**05:00 - 05:30**that we have three Interiors per Spoonful and we didn't use any information about this first dilution in order to do so and we could just keep doing this over and over and over so for example if we want to go to that third dilution well now you have 12 of 12 times one half to the third so 12 times 1 8 so it's 12 divided by 8 is going to give us 1.5 and we could keep doing this over and over and over and so we can mathematically**05:30 - 06:00**figure out the concentration in any one of these tubes if you have a small enough volume it's often the easiest thing to do is to be is to prepare one of these in like a PCR strip or plate so you can keep everything together start by adding your water or buffer to all but the first tube and you want to add the amount that is going to be you want in each tube and we'll get into some more calculations but basically say you were doing a one-to-one dilution so normally you**06:00 - 06:30**would want to do a larger volume than just pipetting one microliter um so you're more accurate in things but just for the sake of making it easy to see the math going on imagine you had one microliter plus one microliter so you were doing a one to two dilution you've got a dilution factor of two you would start by putting one microliter of your buffer or of water into each of these tubes except for the first tube assuming that you don't want that first tube to**06:30 - 07:00**be concentrated at all sometimes if you're using like a multi-channel it's easier to just pipette in the amount into all of the tubes including the first one in that case you can start by having your first tube actually be twice as concentrated as you want your your seat your initial C1 to B and that way you can then once you you're diluting it the first time is actually going to the first two is actually going to be a one to two dilation of that original original stock but at least the rest of them need to have the amount of**07:00 - 07:30**buffer that you want in each of these tubes you don't take the amount you need to transfer out of the first tube into the second tube pipette up down up down up down up down usually I do like five and then I take it into the next tube if you're doing a small volume um if you're doing like a fractional dilution factor to talk about in a second you have a small amount you're going to be have to be really careful that you're mixing thoroughly and might need to take another pipette to actually do the mixing and then take your pipette take it back on the smaller one for the**07:30 - 08:00**transfer make sure that you have like twice or how many factors more of the starting solution so that you don't use it all for your next dilution so if each of these tubes I have 100 microliters but in this one I have 200 microliters so that when I take 100 microliters out of this tube to stick into this tube the volumes are still going there's still going to be 100 microliters left over at the end the last one it'll either have double the volume or if you don't want it to have double the volume you can**08:00 - 08:30**just remove the excess waste so I'm gonna take my pipette set to 100 microliters and transfer from the first well into the second typically do like five up downs and then to the next**08:30 - 09:00**so if I just keep going and I take this out now they each have 100 microliters or if I leave it in now this end one has 200 microliters but the starting one only has a hundred um and again the starting one started with 200 because I needed to take 100 out if you're doing a different dilution factor so like a one to three dilution so with a dilution**09:00 - 09:30**factor of three now in this case say you wanted to add 100 microliters to 200 microliters which wouldn't even fit in these tubes but just go with it in this case we're going to be removing 100 microliters per tube and so we need to make sure that we start with 100 microliters more than we want and in this case we're going to then start with having 300 microliters in the initial tube if we remove 100 from it to the next one which is 200 microliters and then we remove 100 from that now they're all going to still end up with 200**09:30 - 10:00**microliters except for that end one which is going to have 300 microliters and the starting one was going to start with having 300 microliters when you're doing these two you want to make sure that you're not introducing bubbles so each time look and make sure that the pipette the level of liquid in the pipette is the same as before and that you it you don't have any bubbles that you're introducing which are going to mess everything up similarly when we add the buffer in the beginning make sure that there's not any Bubbles at like the bottom that then**10:00 - 10:30**when you put your pipette in you're drawing up air so typically you'll want to give it like a quick spin down or something like this to make sure that all the liquid is going to collect on the bottom of the tube before you go and try to set up your dilution so now let's talk about how you actually set up the violation imagine you want to have a dilution factor of two so a um a one-half each time so you're making it half as concentrated as it was before each time you do a dilution**10:30 - 11:00**in this case if you think about on m1v or c1b1 equals C2 V2 well here are C1 if in each case the concentration of one tube is going to be equal to the concentration of the tube before it divided by the dilution factor so we said our deletion Factor was two so each tube is going to be half as concentrated as the two before which is what we said that we wanted to do another way to think about things is in**11:00 - 11:30**terms of volume so if we go back to our c1b1 equals C2 V2 and we rearrange things a little bit to get our C2 in terms of C1 so what's the ratio of C2 to C1 so for example as we said with that if we're hopping something our ratio is going to be one half but how does that we get that and how can we do this for other things well if we rearrange our this equation to get C2 divided by C1 equals V1 divided by B2 well now what we can do is we can just plug in the**11:30 - 12:00**numbers and so our V1 is going to be the amount the parts of our initial initial solution we're using and V2 is going to be the final so it's going to be that plus how many microliters we had in dilution to get our total volume and now if we go and we do this we plug it in for these different dilution factors for and for these different um scales of these dilution factors so if we did one to one well here if we want to get the ratio of C2 to C1 we can do 1 divided by one plus one so this is**12:00 - 12:30**our initial um this is going to be our initial volume and then this is going to be our final volume so 1 divided by 1 plus 1 1 divided by 2 1 half and you can see that we can do this no matter how we scale this each time so this case we have 2 plus 2 2 divided by 2 plus 2 2 divided by four is one half in each of these cases what we're going to get is that we're going to get this one half keep coming out when we do this equation telling us that we have one-half as the**12:30 - 13:00**ratio of C2 to C1 um and so this is going to be another way that you can see things and we can do this without any dilution factor we want so for example if we have a dilution factor of 3 well now we're going to have one part per three parts total and so in each of these cases our concentration is going to be a third of the original concentration which we can see either in terms of dilution factor or if we go**13:00 - 13:30**back to that c1b1 equals C2 B2 equation and so the dilution factor is just kind of like a simplification of that where we don't have to go through including the volume in each of these cases but sometimes actually going and looking at the volume can make it easier to see what's going on and to set these up so for example if you have a dilution factor of three well now you would have something like one microliter plus two microliters one divided by one plus two is one-third or you could do two plus four so you can see that in this case I've just doubled these both of these**13:30 - 14:00**numbers um because then you're just basically you can multiply everything by the same amount and it's not changing the values of the fact in the fractional terms um but you can also do this just from scratch so you can start by saying okay so if I want five um if I wanted to start with five microliters with my initial how many parts total would I have to have and so you would have to have um three times more parts total as you**14:00 - 14:30**have going in and so if you did 5 times 3 you get 15 so 15 Parts total and you have five parts initial which means that you would have to add 10 microliters of your other solution of your dilution solution dilution factors can also be fractions and this can let you get finer coverage of a narrower range so for example if you have the dilution factor of three halves what this is going to be is that remember each time the concentration is going to be equal to the concentration**14:30 - 15:00**before it's um times the dot divided by the dilution factor and so if we want a dilution factor of two-thirds this means that each time the concentration is going to be the concentration before divided by two-thirds and if you divide something um deletion factors can also be fractions and this is going to give you allow you to get a finer coverage of a narrower range so imagine that you have a dilution factor of three halves this would mean**15:00 - 15:30**that each time you're going to be the concentration is going to be the concentration before it divided by three halves and if you divide by three halves what you're really saying is multiplying it by two-thirds so each time the concentration of one tube is going to be two-thirds the concentration of the tube that was before it um so for example you could do something like two my fingers plus one microliter and if we go back in terms of volume we can see that this would be equal to um two divided by two plus one is**15:30 - 16:00**two-thirds in terms of the concentration for each of these tubes is going to be two-thirds the concentration of the two before it and again we can scale this up so we can say four microliters plus two microliters eight microliters plus four microliters etc etc etc and so in each case we're going to have two parts per three parts total and so we can start with any number for our initial thing so if we wanted to say um starts with 12 we would have 12 parts**16:00 - 16:30**per 12 times 3 is 36 Parts total and so therefore we would have to have 36 minus 12 24 microliters of our buffer of our water um plus 12 microliters of the two before it and so we can do this with any sort of value and this is going to allow us to more easily customize or get greater customization of how far apart our different solutions are in the series**16:30 - 17:00**one of the main reasons why you would do a Serial dilution is to generate a standard curve and so a standard curve is basically where you are measuring some signal and trying to correspond it to a known amount of thing that's giving off that signal so for example if you had a doing an experiment some sort of assay um like a Bradford assay or bsbca assay**17:00 - 17:30**where you're trying to figure out how much protein is in the solution what's the concentration based on how much of this guy signal you get so like how blue or how purple the solution is is going to correspond to how much protein is in there and in order to figure out how much blueness corresponds to how much protein you need to First measure something that has a known concentration so that you can then measure signal from something with an unknown concentration be able to**17:30 - 18:00**compare it to the concentration of those known things to the signal that you would get from those and in that way you can then figure out what the concentration of your unknown was and so I have a whole post on standard standard curves if you're interested in that but this is the basic idea and when you're doing these you're going to need to have a range of values so that you can generate this this curve this standard curve which actually you don't want it to be curvy you want it to be a straight line you could only use it when in the part where it's a straight line but you**18:00 - 18:30**need to generate that wide range of concentrations that's going to give you that line and in order to do this you typically make a stand a Serial dilution because the serial dilution is going to allow allow you to cover a wide range of values the larger your dilution factor The Wider the range of values you're going to be able to cover so if you had for example a dilution with the dilution factor of**18:30 - 19:00**two you go from 12 to 6 to 3 in in two different dilutions two steps if you had a dilution factor of four in those same two steps you would be going from 12 divided by 4 so 12 to 3 3 divided by four um we would have three quarters so 0.75 and you can see that we've covered a larger range of concentrations in the same number of steps so the larger the**19:00 - 19:30**dilution factor though the faster you're going to basically spread out your values so you would spread out your values more in the same number of steps and so you would have a greater kind of like concentration range that you would be covering if you had a smaller dilution factor you would then be covering less so for example if each time you're going to like two-thirds of what you had before well**19:30 - 20:00**then your dilution factor would just be three halves because basically you're dividing it by um dividing it by three halves to get a final concentration of two-thirds um so your state your um dilution factors don't have to be whole numbers so they can even be smaller um when you're doing a smaller dilution factor just make sure make sure make sure that you're really mixing well because it's going to be harder if you're um have a smaller volume that you're going to be transferring each time normally when I mix up and down with the**20:00 - 20:30**pipette when I do the transfer but if you have a small amount um then what you'll probably have to do is have like a second pipette that you're actually using for the mixing so that you make sure you sufficiently mix each time and so you might want to do a larger range if you're expecting a wider range of values and your standard curve whatever um the assay that you're doing the experiment that you're doing it has a sensitivity over a large range you need to make sure that you don't go outside of the linear range of your standard**20:30 - 21:00**curve and again check out the standard curve post for more on this but basically if you're too low for the equipment to detect it if you're too high that you're like saturating it that's not going to be useful and so if you make your dilution factor too high you're going to get points that are below the detection and above the detection um and maybe not so many in the region that's actually detectable and so in this case what you might want to do is start with if you know what the range is start with the high ends of the range do**21:00 - 21:30**a smaller dilution factor so you're just covering the linear range but you're covering it in greater um better resolution kind of you have more values in here you can be more confident about this range um and so if you have the finer range then you want to use a smaller dilution factor if you have a bigger range you want to use a larger dilution factor another reason why Stan why serial dilutions can be helpful is because they**21:30 - 22:00**can allow you to go from a really high range to a really low range in just a couple steps and without having to go directly from a high range to a low range and so if you were to go from 12 tiers to of spoon Cheerios per Spoonful all the way to three Cheerios per Spoonful well what's going to happen is that in this case it's not that bad but what if you had to take one microliter of your 12 Cheerios per Spoonful mix**22:00 - 22:30**um and space or I guess an easier way to say would be like if you took one Cheerio and then you mixed it with 12 spoonfuls of milk what if when you were taking that one Cheerio you weren't very accurate and there was another Cheerio stuck on your spoon when you were doing the transfer well now you're going to have a different concentration you're going to have a concentration of two Cheerios per um per 12 spoonfuls of milk so that would be twice as much as you wanted to get similarly if you are pipetting some sort**22:30 - 23:00**of solution you have some stuck on the outside well now your concentration is going to be way off if however you started with a more dilute dilution um then what would happen was that that bit that was stuck on the outside of the spoon well it would be more likely to be milk um and so basically you would be less likely to to make a big mistake in your concentration so the more dilute something is when you're pipetting it**23:00 - 23:30**um the less it matters if there's a little bit stuck on the inside or on the outside of your pipette tip not that you want that to happen um but there's going to be less of that error so the you want to be not constant not pipetting a small amount of something really concentrated because that's going any little bit extra is going to have a big effect you also don't want to be pipetting really small amounts so if you can pipette a bigger amount um you're going to be more likely to be accurate and so**23:30 - 24:00**by doing things step wise um you can then avoid having to pipette those really small volumes where you're doing something like one microliter into 10 mils of volume not only is that not going to be very accurate but also now you end up with 10 mils of some solution where you really don't need 10 mils of a solution so step by Solutions are going to be really helpful and you don't always have to do a stepwise solution in a Serial fashion so you might want to dilute something like one to a hundred and then one two**24:00 - 24:30**um one to two hundred or something like that it doesn't have to be the same each time but this is going to come in really handy when you're doing things like diluting a nucleic acid solution where you have you order your primer and it comes in a you get it really cons it's really concentrated at first and you don't need it that concentrated but you don't want to dilute it directly and have to be pipetting out like 0.5 microliters and then mixing it with 10 milliliters that's not what you want to do instead you would use stepwise dilutions**24:30 - 25:00**um but the cereal dilution is it's just a special case of the stepwise dilution where each time you're diluting it by the same amount and the same amount the number of times you're diluting it by is this dilution factor or DF and if you know the dilution factor you can then do calculations to figure out the concentration in any of your dilution tubes based on just knowing the initial concentration and that dilution factor so hope I've convinced you that serial dilutions are useful and that you can do**25:00 - 25:30**cool things with them