-
- Posts: 4
- Joined: Wed Jan 01, 2014 7:51 am
Alternative for mobile phase
Basic questions from students; resources for projects and reports.
10 posts
Page 1 of 1
Hi guys. I'm new here and I really need some help. I'm currently doing a project which requires me to use HPLC in order to detect ascorbic acid. The problem is at my university, we don't have dihydrogen ammonium phosphate to use as the mobile phase. So, I was wondering if there are any chemicals that can replace dihydrogen ammonium phosphate as the mobile phase? Thanks in advance.
- tom jupille
- Site Admin
-
- Posts: 4978
- Joined: Wed Aug 11, 2004 4:55 pm
- Location: Alamo, CA / USA
Ammonium dihydrogen phosphate is a solid, so it cannot be used by itself as a mobile phase. What you need is a solution of it at some concentration, at some pH, in some solvent. Get a chemistry prof or graduate student to explain how to prepare it at the appropriate concentration from ammonium hydroxide, phosphoric acid, and dihydrogen monoxide.
-- 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: 4
- Joined: Wed Jan 01, 2014 7:51 am
Can I just change it to other chemicals? Some that might be equivalent to it as the mobile phase?
- tom jupille
- Site Admin
-
- Posts: 4978
- Joined: Wed Aug 11, 2004 4:55 pm
- Location: Alamo, CA / USA
No, you can't "just" change it without changing a lot of other parameters as well. In any case, ammonium phosphate is a common chemical which should not be difficult to obtain in Malaysia.
Before we all waste a lot of time & effort, why don't you tell us something about your background & experience level, what exactly you are trying to accomplish, and what resources you have available?
Before we all waste a lot of time & effort, why don't you tell us something about your background & experience level, what exactly you are trying to accomplish, and what resources you have available?
-- 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: 38
- Joined: Mon Sep 13, 2010 8:46 am
tom jupille wrote:
Ammonium dihydrogen phosphate is a solid, so it cannot be used by itself as a mobile phase. What you need is a solution of it at some concentration, at some pH, in some solvent. Get a chemistry prof or graduate student to explain how to prepare it at the appropriate concentration from ammonium hydroxide, phosphoric acid, and dihydrogen monoxide.
This sounds like very dangerous substance
-
- Posts: 4
- Joined: Wed Jan 01, 2014 7:51 am
Ok, I'll will explain in detail. First, I'm a diploma student and currently doing a final year project. The project that I've been researching for a while now is the extraction of ascorbic acid in order to find out the existence of ascorbic acid in fruits.
For the extraction, I've been using metaphosphoric acid and trichloro acetic acid as the solvents for extraction.
The only thing that is left is the analysis. Based on the journal that I've been using, it said that it uses dihydrogen ammonium phosphate as the mobile phase and a c18 column hplc. The thing is, we don't have that particular mobile phase to use and it will be too late to order them right now as the lab assistant will be on leave soon. So I'm kind of stuck right now and that's the reason why I'm trying to find an alternative way or chemicals to replace the dihydrogen ammonium phosphate. Perhaps you could recommend me the conditions of hplc for the detection of ascorbic acid other than the one that using dihydrogen ammonium phosphate.
Any help will definitely be appreciated.
For the extraction, I've been using metaphosphoric acid and trichloro acetic acid as the solvents for extraction.
The only thing that is left is the analysis. Based on the journal that I've been using, it said that it uses dihydrogen ammonium phosphate as the mobile phase and a c18 column hplc. The thing is, we don't have that particular mobile phase to use and it will be too late to order them right now as the lab assistant will be on leave soon. So I'm kind of stuck right now and that's the reason why I'm trying to find an alternative way or chemicals to replace the dihydrogen ammonium phosphate. Perhaps you could recommend me the conditions of hplc for the detection of ascorbic acid other than the one that using dihydrogen ammonium phosphate.
Any help will definitely be appreciated.
-
- Posts: 38
- Joined: Mon Sep 13, 2010 8:46 am
You can check Google for application notes. What is the sample matrix?
Maybe useful link: http://www.sielc.com/Compound-Vitamin-C.html
http://naldc.nal.usda.gov/download/7342/PDF
Maybe useful link: http://www.sielc.com/Compound-Vitamin-C.html
http://naldc.nal.usda.gov/download/7342/PDF
-
- Posts: 2071
- Joined: Tue Aug 17, 2004 7:59 pm
- Location: 38.590967, -90.213236
Look around for Ammonium Phosphate Monobasic.
A rose by any other name...
A rose by any other name...
Thanks,
DR
DR
-
- Posts: 4
- Joined: Wed Jan 01, 2014 7:51 am
Thanks for all of the suggestions.
And Uros, Thanks for the link and journal. It really helped me a lot.
Decision still have to be made. I hope the suggestions can keep on coming. All helps are welcomed and appreciated. Thanks a lot guys.
And Uros, Thanks for the link and journal. It really helped me a lot.
Decision still have to be made. I hope the suggestions can keep on coming. All helps are welcomed and appreciated. Thanks a lot guys.
-
- Posts: 3475
- Joined: Mon Jan 07, 2013 8:54 pm
- Location: Western Kentucky
kayaii wrote:
Thanks for all of the suggestions.
And Uros, Thanks for the link and journal. It really helped me a lot.
Decision still have to be made. I hope the suggestions can keep on coming. All helps are welcomed and appreciated. Thanks a lot guys.
http://www.restek.com/pdfs/59398.pdf
This one used a Potassium Phosphate buffer and C18 column.
You may want to browse through the Restek site and see if there are other combinations which you may be able to replicate with what you have on hand.
The past is there to guide us into the future, not to dwell in.
10 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