elvisd
Harmless
Posts: 6
Registered: 1-3-2009
Member Is Offline
Mood: No Mood
|
|
manganese concentration
Doing some stream monitoring as a school project. Does anyone have a basic, clear procedure for this? We've got an inexpensive spectrophotometer.
The sampled area in question has come up with concentrations ranging from 0.01-4.20 in the past.
|
|
|
Ozone
International Hazard
Posts: 1269
Registered: 28-7-2005
Location: Good Olde USA
Member Is Offline
Mood: Integrated
|
|
Test kits are available:
http://www.aquaspex.com.au/products/testkits/microtest/Manga...
Those look a lot safer (and more reliable) than the classical method (which I have attached, Purdy 1955). ***Well, maybe not. It looks like the modern
test kits are not much advanced over the 1955 procedure. A competitor (Lamotte, attached) actually describes their 3 "magic" reagents A-C as "hardness
reagent", manganese reagent (PAN, (1-[2-Pyridylazo]-2-Naphthol), and NaCN (10%) stabilizer.
Formaldoxime will also work, and a kit is built around that. Ni can interfere with this test:
http://www.mn-net.com/StartpageWaterAnalysisTesting/VISOCOLO...
The simplest thing (IMO) would be to convert it to MnO4+ (Mn 7+) with household bleach (NaOCl, 5-6% as FAC) and monitor with your spec.
Mn 7+ is a charge transfer complex:
http://www.chemistry.sfu.ca/assets/uploads/file/Course%20Mat...
The color of Mn 7+ is intense and can be easily seen (naked eye) at ppm concentrations. If you can see it, the spec can see it--if you tell it where
to look.
The UV-VIS absorption for Mn 7+ is complex and interesting, I would recommend that you measure a known amount of that at 2-4 nm intervals (e.g. manual
scanning of the absorbance wavelength) between 425 and 600nm and plot the absorbances on graph paper, or on the computer. The best absorbance
(highest) would be chosen for further analytical work.
You can check your findings against the attached .ppt (not mine, but I could not get a url for it).
Cheers,
O3
Attachment: Purdy and Hume 1955 Anal. Chem. 27 (2).pdf (370kB)
This file has been downloaded 711 times
Attachment: Lamotte Test kit.pdf (84kB)
This file has been downloaded 355 times
Attachment: Ultraviolet permanganate.ppt (766kB)
This file has been downloaded 2685 times
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by elvisd  | | Doing some stream monitoring as a school project. Does anyone have a basic, clear procedure for this? We've got an inexpensive spectrophotometer.
The sampled area in question has come up with concentrations ranging from 0.01-4.20 in the past. |
0.01-4.20 of what? Apples? Pears? Airheads?
|
|
|
Ozone
International Hazard
Posts: 1269
Registered: 28-7-2005
Location: Good Olde USA
Member Is Offline
Mood: Integrated
|
|
I assumed mg/L.
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
|
|
|
elvisd
Harmless
Posts: 6
Registered: 1-3-2009
Member Is Offline
Mood: No Mood
|
|
mg/L. I guess I was the airhead. Sorry.
Thank you for the valuable information, Ozone. Very rewarding.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
