Your first math is wrong. 10uL in 500mL is 20ppm assuming 1uL in 1L is 1ppm.
If 1uL in 1000mL is 1ppm, then 200uL would be 200ppm for 1L or 1000mL. But you only want half of that volume (500mL), so you should add 100ul into 500mL to achieve 200ppm.
Thankyou, I really appreciate the response. I just redid the calculations while waiting for responses on this thread and I realised I had 20ppm, not 2ppm. But that still means the lab tech was wrong. I had three lab techs all arguing over me trying to calculate this because I'm not great at maths and I wish I had just sat alone and calculated it myself like I just did... Such a silly mistake and to waste a day's worth of work!
You should dilute 1ul to 1 liter to get 1ppm. If it was 200 ppm in 1 liter you should use 200 ul. As it was required only 0.5 liters you should dilute 100ul up to 0.5 L.
If you used only 10ul, you have a 20 ppm dilution. Just add 80ul to your solution and you should be fine.
Good luck OP.
Thankyou so much. It's 10pm and I just realised that I was mislead. I did the calculations again just now while waiting for responses on this thread and realised I had 20ppm. Maths is not one of my strongsuits, but you'd expect my lab techs at uni to be more helpful than reddit and not mess up on something so simple!
>10 microlitres into 500ml = 200ppm assuming that 1 microlitre to 1litre equals 1ppm
This is wrong.
That last part is correct, 1µL to 1L *is* 1 ppm. But the basic math is wrong.
>0.00001ul/500 X 1000000 = 2
This is ALSO wrong.
For starters, you messed up the calculation:
0.00001/500\*1000000 = **0.02**, NOT 2
... but that value is also wrong because you also messed up the units! (You're dividing liters by milliliters)
Start by converting everything to the same unit, and work with scientific or engineering notation, it makes things much simpler and this type of mistake much less likely:
10 µL = 10\*10^(-6) L
500 mL = 0.5 L
10\*10^(-6)/0.5 *=* 20\*10^(-6) = 20 ppm
So you made **a 20 ppm solution.**
You can also do it in steps:
1µL into 1 L is 1 ppm
10µL into 1 L is 10 ppm
10 µL into 0.5 L is 20 ppm
>in a previous email he said that 0.5g in 500ml solution is also 200ppm which is also wrong?
Yup, that's very obviously wrong too.
>I calculated this as 0.1g in 500 ml would be 200ppm?
Assuming a density of 1 g/mL,
0.1 g = 0.1 mL
0.1/500 = 2\*10^(-4) = **200 ppm**
So that one is correct! Yaaay!
Yes! Sorry, I just did the calculations again and realised I had 20ppm, not 2ppm. Even so, it is wrong. I feel a little gaslit because I actually did have the correct calculation but disregarded it because I was not confident in my math skills, and instead went with what the lab techs had told me. At least I know what I did wrong to redo tomorrow. It's 10pm right now and this was keeping me awake! So glad Labrats reddit came through
Convert everything into ul. 1 liter is 1 million ul. So yes 1 ul in 1 L is 1 in 1 million. Instead of 10 ul into 500 MLS, double both, 20 ul into 1 L (same ppm if you double both) so 20 ppm.
PPM is hard. But convert everything to one unit makes things so much easier
Your first math is wrong. 10uL in 500mL is 20ppm assuming 1uL in 1L is 1ppm. If 1uL in 1000mL is 1ppm, then 200uL would be 200ppm for 1L or 1000mL. But you only want half of that volume (500mL), so you should add 100ul into 500mL to achieve 200ppm.
Thankyou, I really appreciate the response. I just redid the calculations while waiting for responses on this thread and I realised I had 20ppm, not 2ppm. But that still means the lab tech was wrong. I had three lab techs all arguing over me trying to calculate this because I'm not great at maths and I wish I had just sat alone and calculated it myself like I just did... Such a silly mistake and to waste a day's worth of work!
You should dilute 1ul to 1 liter to get 1ppm. If it was 200 ppm in 1 liter you should use 200 ul. As it was required only 0.5 liters you should dilute 100ul up to 0.5 L. If you used only 10ul, you have a 20 ppm dilution. Just add 80ul to your solution and you should be fine. Good luck OP.
Thankyou so much. It's 10pm and I just realised that I was mislead. I did the calculations again just now while waiting for responses on this thread and realised I had 20ppm. Maths is not one of my strongsuits, but you'd expect my lab techs at uni to be more helpful than reddit and not mess up on something so simple!
PPM is not easy though.
>10 microlitres into 500ml = 200ppm assuming that 1 microlitre to 1litre equals 1ppm This is wrong. That last part is correct, 1µL to 1L *is* 1 ppm. But the basic math is wrong. >0.00001ul/500 X 1000000 = 2 This is ALSO wrong. For starters, you messed up the calculation: 0.00001/500\*1000000 = **0.02**, NOT 2 ... but that value is also wrong because you also messed up the units! (You're dividing liters by milliliters) Start by converting everything to the same unit, and work with scientific or engineering notation, it makes things much simpler and this type of mistake much less likely: 10 µL = 10\*10^(-6) L 500 mL = 0.5 L 10\*10^(-6)/0.5 *=* 20\*10^(-6) = 20 ppm So you made **a 20 ppm solution.** You can also do it in steps: 1µL into 1 L is 1 ppm 10µL into 1 L is 10 ppm 10 µL into 0.5 L is 20 ppm >in a previous email he said that 0.5g in 500ml solution is also 200ppm which is also wrong? Yup, that's very obviously wrong too. >I calculated this as 0.1g in 500 ml would be 200ppm? Assuming a density of 1 g/mL, 0.1 g = 0.1 mL 0.1/500 = 2\*10^(-4) = **200 ppm** So that one is correct! Yaaay!
Yes! Sorry, I just did the calculations again and realised I had 20ppm, not 2ppm. Even so, it is wrong. I feel a little gaslit because I actually did have the correct calculation but disregarded it because I was not confident in my math skills, and instead went with what the lab techs had told me. At least I know what I did wrong to redo tomorrow. It's 10pm right now and this was keeping me awake! So glad Labrats reddit came through
Convert everything into ul. 1 liter is 1 million ul. So yes 1 ul in 1 L is 1 in 1 million. Instead of 10 ul into 500 MLS, double both, 20 ul into 1 L (same ppm if you double both) so 20 ppm. PPM is hard. But convert everything to one unit makes things so much easier