Hi Sabrina,

do you want to do it with wet chemistry techniques or instrumental analysis? what is the expected concentration range of your analyte and your inteference?

Hi Markus,

I don't mind to try both in wet chemistry and instrumental analysis. Currently, I have tried using AAS Flame method (as follow the ASTM method) but thru my reading it is has interference if the concentration more than 2 mg/L. Furthermore, during the preparation I have added 1,10-phenanthroline to form complexes of iron. Expected concentration is 0.003 g/L.

Dear Sabrina

With this you haven't given us much information regarding your system. If you wanted a most simple separation to remove iron from your Ni system you can extract or precipitate the iron. Although this is pH dependent. I would suggest looking at old school editions of analytical chemistry. You could determine both by titration with the addition of a complexing agent to screen one metal from another. All in all I would suggest ICP-OES for the measurement of both ion concentrations in tandem with ICP-MS for the nickel (as iron has a lot of interferences).

Here is a method outside of the usual box utilizing extraction spectrophotometry. - http://nopr.niscair.res.in/bitstream/123456789/5119/1/JSIR%2064(8)%20581-584.pdf

Dear Sabrina,

Flame-AAS should be ok for the determiniation of Ni at 3 mg/L, taking in account that Flame-AAS DL for Ni is in the range of 0.006 mg/L.

I have a couple of questions for you:

1) how can you write that Fe at 2 mg/L can already interfere on Ni determination ? The "recommended" conditions for Ni determination by AAS-Flame reports that high Fe levels interferes on Ni determination by enhancing Ni absorption, but this problem can easily be solved by using matrix matching or standard additions.

2) are you maybe using a multi-element lamp with Fe in the cathode ? If this is the case, than instead of using the default Ni wavelength (232.0 nm) you should go to a secondary Ni line (i.e 352.5 or 354.5 nm), because at 232.0 there is also a Fe line within the 0.2 nm slit.

3) What is the Fe concentration, is it 1 g/L ? 10 g/L ? 100 g/L ?

Best regards,

Riccardo

Thanks Mark Ogden !!!!!

Hi Riccardo !

Thanks for your information. I am currently using the multi element lamp with Fe in the cathode. Will try to change the wavelength as you recommended. My total Fe concentration is 10 g/L. What do you advise the concentration that I need to add in my sample in order to for me to solve the absorption problem.

Thanks in advance.

Regards,

Sabrina

Hi Sabrina,

let's test the problem one piece at a time:

- in case you don't have a Ni single element lamp, go changing first the Ni wavelength (do not forget the slit);

- if you have a 10 g/L Fe standard (pure std), than you may want to check for bkgd absorption, maybe you should use the bkgd correction (deuterium, if available);

- in case the pure 10 g/L Fe std is not available, than you should analyze your sample twice, one in normal mode, and one with bkgd corr, in order to evaluate bkhd absorption, but I am quite sure you should use it;

- and if you have the 10 g/L pure Fe std, you can use this for matrix matching, that is you could prepare your Ni standards in this 10 g/L Fe, that you will also use for zeroing the AAS

- finally, if the 10 g/L pure Fe std is not available, than you better go for the standard additions method.

Regards,

Riccardo

Ni very nicely complexed and pptd with DMG, i think there is no interference with Fe in that.. which yields a very good accrurate result (less than 0.5%)error.

what is pptd and DMG ?

Ni ppts as Ni(DMG)2

DMG is DimethylGlyoxime

ICP/MS OR AAS are the best methods

wuth the help of gravimetric analysis you find out the Ni concentration using DMG precipitation study

FAAS methods

If your nickel concentration is good enough than go for the Ni(DMG)2 method. If concentration is low than you can try with ICP also. In AAS you need to change the wavelength as adviced earlier.

If your Ni concentration in PPM, , then u use Flame AAS and if it is in PPB then use Graphite Furnace AAS/ICP

You can also try with a polarographic method

Depends on the concentration of Nichel; if it is a galvanic solution Nickel Bath you are in the range of g/l and you can operate a Ni titration with EDTA: the procedure is very simple and now I describe:

Take 2 ml of your bath

Put in a bekcer

Add 30 ml of ammonia 33%

mix

Titrate with EDTA 0,1 M

Results: multiply EDTA ml used for 2,936 and you got Ni g/l

Iron has no interference as in the basic ammonia environment precipitates

AAS, ICP and Polarography are the best methods for low concentration of the metal; under the g/l

For intermediate concentration is possible to set up a photometric Visible method where nickel is complexed with ammonia in a ammonia buffer solution; here is compared with note concentrations Ni samples

Please feel free to contact me for details if you need

For sure ICP-MS is Ni conncetrations are low. You can separate Fe from Ni wth DMG and solubilize the nickel on DMG by a 1M HNO3. You can also use GF-AAS using or not the same separation strategy

ICP OES is a wonderful technique offering low limits of detection, large working linear range, and a possibility to determine both major, minor and trace elements in the same sample. However, due to spectral interferences you should carefully select working lines and validate your method (Fe is particularly reach with emission lines, interfering strongly with other trace elements