Jump to content

  • Log in with Facebook Log in with Twitter Log in with Windows Live Log In with Google      Sign In   
  • Create Account

Submit your paper to J Biol Methods today!
Photo
- - - - -

100 micro molar to 250 micro molar


  • Please log in to reply
17 replies to this topic

#1 uzalive

uzalive

    member

  • Active Members
  • Pip
  • 6 posts
2
Neutral

Posted 25 September 2012 - 11:31 AM

1. You are provided with an antibody solution Ab that has a concentration 600 ug/ul. For lab it is necessary to make thefollowing dilutions.

a. 10 ul of 600 ug/ul Ab + 190ul of buffer to make a 1:20 dilution at _________ ug/ul.

b. 20 ul of 1:20 +40 ul of buffer to make a 1:60 dilution at __________ ug/ul.

c. 5ul of 1:60 + 5ul of buffer to make a ________ dilution at _________ug/ul.

It seems I am missing dome concepts. Could someone help?

#2 bob1

bob1

    Thelymitra pulchella

  • Global Moderators
  • PipPipPipPipPipPipPipPipPipPip
  • 5,722 posts
399
Excellent

Posted 25 September 2012 - 12:45 PM

This is homework - tell us what you think and we will help correct/expand your answers.

#3 ascacioc

ascacioc

    Veteran

  • Global Moderators
  • PipPipPipPipPipPipPipPipPipPip
  • 271 posts
44
Excellent

Posted 25 September 2012 - 01:45 PM

This is the second one today... as I said: on our times we did our HWs alone or googled for the answers. Not asked directly others. How will you learn?

#4 uzalive

uzalive

    member

  • Active Members
  • Pip
  • 6 posts
2
Neutral

Posted 25 September 2012 - 02:08 PM

I did not answer the question at first this is how I did it

a. 10ul times 600ug/ul =6000 ug

add the buffer, which is 190 ul, to 10ul to get 200 total ul.

6000ug/200= 30 ug/ul

I don't understand how do we know that it is 1:20 dilution.


b. 600ug/ul/ 20=30 ug/ul

30 ug/ul times 20ul=600ug/ 60 ul= 10 ug/ul

I don't understand why the it is a 1:60 dilution. I don't understand why 1:60 dilution was given. I did not use it in solving the question, but my answer is correct.

Am I missing something.

c. 600ug/ul/60=10ug/ul times 5ul=50 ug

50 ug/10ul= 5ug/ul I could not figure out the dilution.

#5 bob1

bob1

    Thelymitra pulchella

  • Global Moderators
  • PipPipPipPipPipPipPipPipPipPip
  • 5,722 posts
399
Excellent

Posted 25 September 2012 - 03:07 PM

I did not answer the question at first this is how I did it

a. 30 ug/ul

I don't understand how do we know that it is 1:20 dilution.

Correct. Dilution ratios work like fractions 1:20 is a 1 part in 20 therefore 600/20 = 30ug/ul...

b. 10 ug/ul

I don't understand why the it is a 1:60 dilution. I don't understand why 1:60 dilution was given. I did not use it in solving the question, but my answer is correct.

Am I missing something.

1:60 of the original solution. 600/60 = 10 ug/ul.

c. 600ug/ul/60=10ug/ul times 5ul=50 ug

50 ug/10ul= 5ug/ul I could not figure out the dilution.

To calculate the ratio do the inverse of what you would do for working out the concentration- so 600ug/ul / 5 ug/ul =...

#6 El Crazy Xabi

El Crazy Xabi

    Veteran

  • Active Members
  • PipPipPipPipPipPipPipPipPipPip
  • 199 posts
20
Excellent

Posted 25 September 2012 - 08:44 PM

One comment, 1/20 is not 1:20

1/20 -> one part of x IN 20 parts

1:20 -> one part of x AND 20 parts of y

#7 bob1

bob1

    Thelymitra pulchella

  • Global Moderators
  • PipPipPipPipPipPipPipPipPipPip
  • 5,722 posts
399
Excellent

Posted 26 September 2012 - 01:30 AM

Most people would use 1 part with 19 parts diluent to give 1:20, as in the example questions above.

#8 Astilius

Astilius

    Enthusiast

  • Active Members
  • PipPipPipPipPip
  • 50 posts
4
Neutral

Posted 26 September 2012 - 03:14 AM

One comment, 1/20 is not 1:20

1/20 -> one part of x IN 20 parts

1:20 -> one part of x AND 20 parts of y


You would think so, but no. 1:20 when talking about dilutions is 1 part in 20 (or 1 part X + 19 parts Y)
It looks like a mathematical ratio but it's never used like one.
To the last, I grapple with thee; from Hell's heart, I stab at thee; for hate's sake, I spit my last breath at thee.

#9 Trof

Trof

    Brain on a stick

  • Global Moderators
  • PipPipPipPipPipPipPipPipPipPip
  • 1,200 posts
109
Excellent

Posted 26 September 2012 - 06:22 AM

1:20 is a confusing notation and should be abandoned. Because you're never really sure if it's a dilution or a ratio of solute and solvent.
Why can't just people say '20 times diluted' or '1 in 20 dilution'?

Our country has a serious deficiency in lighthouses. I assume the main reason is that we have no sea.

I never trust anything that can't be doubted.

'Normal' is a dryer setting. - Elizabeth Moon


#10 El Crazy Xabi

El Crazy Xabi

    Veteran

  • Active Members
  • PipPipPipPipPipPipPipPipPipPip
  • 199 posts
20
Excellent

Posted 27 September 2012 - 07:53 PM


One comment, 1/20 is not 1:20

1/20 -> one part of x IN 20 parts

1:20 -> one part of x AND 20 parts of y


You would think so, but no. 1:20 when talking about dilutions is 1 part in 20 (or 1 part X + 19 parts Y)
It looks like a mathematical ratio but it's never used like one.


Maybe you don't, but I use both notations. It's not the first time finding mixes with 70:25:5 of x,y and z and similar. That's why I keep the ration and fraction notation separated. Also because I learned it in that way. It can also be a cultural stuff like the number of continents or the number of lives of cats Posted Image

Textbook: http://www.hofstra.e...d_dilutions.pdf
see page 29 (It's not what I think, it's also in a book)

There is an old thread about and each people use one or another
http://www.protocol-...osts/31255.html

#11 Astilius

Astilius

    Enthusiast

  • Active Members
  • PipPipPipPipPip
  • 50 posts
4
Neutral

Posted 28 September 2012 - 04:57 AM

Interesting. Though, component ratios (e.g. 1:2:1:5) are not the same as dilutions.
The obvious difficulty lies if it's a two component ratio, the resulting notation could easily be ambiguious.

Looking at everyone's favourite, Wikipedia, I see this: http://en.wikipedia....#Dilution_ratio

But yes, there is often much confusion with this, but it should be clear, either by declaration or context if a ratio or dilution were involved.

I also think Trof is onto something -- I have seen many, many people confused over this and the notation isn't helping. Someone want to write up a letter and submit a suggestion of new notation to Nature?

Edited by Astilius, 28 September 2012 - 04:59 AM.

To the last, I grapple with thee; from Hell's heart, I stab at thee; for hate's sake, I spit my last breath at thee.

#12 bob1

bob1

    Thelymitra pulchella

  • Global Moderators
  • PipPipPipPipPipPipPipPipPipPip
  • 5,722 posts
399
Excellent

Posted 28 September 2012 - 03:00 PM

There's also the point that after a certain level of dilution, it really doesn't matter whether you are using the fraction or ratio. For example, 1:5 (one part and 5 parts) is 0.166, whereas 1/5 is 0.2, sure biggish difference, but when you get out to say 1:100 (0.0099) vs 1/100 (0.01) really, what's the difference?

#13 Trof

Trof

    Brain on a stick

  • Global Moderators
  • PipPipPipPipPipPipPipPipPipPip
  • 1,200 posts
109
Excellent

Posted 28 September 2012 - 10:31 PM

Difference is when people don't understand dilution factor notation at all, they may actually use it wrong when it matters.
Besides, for some applications it does matter even then, for example if you're doing standard curve by serial dilution, you better have the exactly correct ratio, otherwise your results would be screwed.

Our country has a serious deficiency in lighthouses. I assume the main reason is that we have no sea.

I never trust anything that can't be doubted.

'Normal' is a dryer setting. - Elizabeth Moon


#14 uzalive

uzalive

    member

  • Active Members
  • Pip
  • 6 posts
2
Neutral

Posted 29 September 2012 - 10:02 AM

You have an antibody solution that has a concentration of 600 ug/ul. You want to make th following dilutions.

10 ul of 600 ug/ul Ab +190 ul of buffer to make a 1:20 dilution at ________ ug/ul.


This is how I did it.

1. 600 ug/ul times 10 ul= 6000 ug

2. 6000 ug/200ul= 30ug/ul


I know that this answer is correct because I checked. I don't understand how this gives you a 1:20 dilution. Why is the 1:20 given? I did not use it in my calculations. It seems that I am missing some concept. Can someone clarify this. I would have thought that you would divide 30 ug/ul by 20.

Uzalive

#15 pito

pito

    Veteran

  • Global Moderators
  • PipPipPipPipPipPipPipPipPipPip
  • 1,332 posts
81
Excellent

Posted 29 September 2012 - 10:07 AM

if you go from 6000µg to 30µg, then you diluted it 20 times.
6000/20 = 30

and where does the 1:20 comes from (without making the math of the antibody) 10 µl and 190 µl , is 10 µl in 200 µl in total, its 1:20 , 1 part of 20 parts in total or 10 parts of 200 parts in total.

If you don't know it, then ask it! Better to ask and look foolish to some than not ask and stay stupid.





Home - About - Terms of Service - Privacy - Contact Us

©1999-2013 Protocol Online, All rights reserved.