Chromatography Forum

Posted: **Thu Nov 12, 2009 3:55 pm**

Hello --

I am rather new to LC-MS and have a question...

I was wondering whether or not it is possible to detect anions (such as perchlorate) with LC/MS (electrospray) rather than using standard ion chromatography with conductivity detector? Are anions identifiable with an appropriate HPLC column using LC/MS?

Thanks for sharing your thoughts.

Posted: **Thu Nov 12, 2009 5:54 pm**

Hi,
Some anions ("free" forms) can be detect by -ESI MS (I analyzed arsenite and arsenate ions + other arsenic species in plant extracts)... many problems - sensitivity (IE and RP modes) and other. I don't recommend you choose LC-ESI MS for determination inorganic ions (especially at low concentration <1-10ppm). You can use LC-ESI MS for identification some ions in "trouble" cases (at high concentrations). IE, RP (not IPC!!!), and HILIC can be used for separation some anions.

best regards, Alex.

Posted: **Fri Nov 13, 2009 9:42 pm**

Even if you could do this with LCMS you wouldn't be performing the analysis as specified in the EPA method. There is some flexibility in EPA methods, but if it is an ion chromatography method it must be done on an ion chromatograph if the results are reported as determined by a specific method.

Posted: **Sat Nov 14, 2009 11:34 pm**

You can do it. My lab runs it all the time. I'm fairly certain my boss had a helping hand in developing the method with the EPA.

http://www.caslab.com/EPA-Methods/PDF/6850.pdf

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