-
- Posts: 6
- Joined: Thu Jan 12, 2017 1:43 pm
unknown volume hplc
Basic questions from students; resources for projects and reports.
6 posts
Page 1 of 1
I have a known concentration and peak area is it possible to work out the volume?
-
- Posts: 404
- Joined: Wed Nov 09, 2016 12:43 am
Perhaps. It would be;
Concentration (let's say ug/mL) x Injection Volume (in mL) = ug (Mass)
where 1 mL = 1000 uL
Peak area has nothing to do with the calculation. Remember, HPLC is a 'mass' device and not volume. Why do you want to know?
Concentration (let's say ug/mL) x Injection Volume (in mL) = ug (Mass)
where 1 mL = 1000 uL
Peak area has nothing to do with the calculation. Remember, HPLC is a 'mass' device and not volume. Why do you want to know?
-
- Posts: 404
- Joined: Wed Nov 09, 2016 12:43 am
To calculate the actual volume of the peak you will need to know the detector response versus the concentration of the target molecule. It should be a linear curve.
- tom jupille
- Site Admin
-
- Posts: 4978
- Joined: Wed Aug 11, 2004 4:55 pm
- Location: Alamo, CA / USA
There's more than a bit of ambiguity here:
1. Where/how is your "known concentration" determined? Is it the concentration of the sample that was injected? Is it the concentration at the peak maximum (and if so, how did you determine it)?
2. What units are you using for peak area? Integrator counts? mV?
3. What volume are you trying to determine (the volume injected? the volume of the peak itself?)
4. If you're after the volume of the peak, what fraction of the analyte do you wish to account for? Chromatographic peaks are, to a good first approximation, Gaussian. The "baseline" width of a peak is approximately 4 x sigma, and so includes roughly 95% of the area. Is that what you want, or are you looking at 99%, or . . . ?
1. Where/how is your "known concentration" determined? Is it the concentration of the sample that was injected? Is it the concentration at the peak maximum (and if so, how did you determine it)?
2. What units are you using for peak area? Integrator counts? mV?
3. What volume are you trying to determine (the volume injected? the volume of the peak itself?)
4. If you're after the volume of the peak, what fraction of the analyte do you wish to account for? Chromatographic peaks are, to a good first approximation, Gaussian. The "baseline" width of a peak is approximately 4 x sigma, and so includes roughly 95% of the area. Is that what you want, or are you looking at 99%, or . . . ?
-- Tom Jupille
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374
-
- Posts: 6
- Joined: Thu Jan 12, 2017 1:43 pm
i have a calibration curve of conc vs peak area
I am trying to determine how much volume of a drink you have to consume to be toxic (500mM)
the peak area units is (iss)
I am trying to determine how much volume of a drink you have to consume to be toxic (500mM)
the peak area units is (iss)
- tom jupille
- Site Admin
-
- Posts: 4978
- Joined: Wed Aug 11, 2004 4:55 pm
- Location: Alamo, CA / USA
Ok. So you inject a sample of your drink and measure the peak area of the compound of interest. Use your calibration curve to convert that to concentration.
Concentration is mass (or moles) divided by volume. You should be able to take it from there.
Concentration is mass (or moles) divided by volume. You should be able to take it from there.
-- Tom Jupille
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374
6 posts
Page 1 of 1
Who is online
In total there is 1 user online :: 0 registered, 0 hidden and 1 guest (based on users active over the past 5 minutes)
Most users ever online was 1117 on Mon Jan 31, 2022 2:50 pm
Users browsing this forum: No registered users and 1 guest
Most users ever online was 1117 on Mon Jan 31, 2022 2:50 pm
Users browsing this forum: No registered users and 1 guest
Latest Blog Posts from Separation Science
Separation Science offers free learning from the experts covering methods, applications, webinars, eSeminars, videos, tutorials for users of liquid chromatography, gas chromatography, mass spectrometry, sample preparation and related analytical techniques.
Subscribe to our eNewsletter with daily, weekly or monthly updates: Food & Beverage, Environmental, (Bio)Pharmaceutical, Bioclinical, Liquid Chromatography, Gas Chromatography and Mass Spectrometry.
- Follow us on Twitter: @Sep_Science
- Follow us on Linkedin: Separation Science