Hello Guys, wonder if you could give me an advice.
So, i`m digesting HCFeCr (high-carbon ferrochrome) in microwave and i can digest my sample entirely in two ways.
1 - HNO3/HF solution
2 - HCl/HNO3 solution
Ideally i would like to use these solution to obtain Si and P content in FeCr.
In first (HNO3/HF) case I understand that i will need to perform "complexation of HF" with saturated H3BO3.
Could you explain how i should perform this "complexation". I tried simply adding the saturated H3BO3 in sample, but it did not help, i still had huge concentrations of Si (from the chamber, which is made of quartz, Swiching to teflon is not an option right now). Should i perform another digestion in microwave with H3BO3 and shoould i use saturated solution or can i use crystaline H3BO3 (i`ve read, that it takes about 500mg of H3BO3 per mL of HF).
In second case (HCl/HNO3) - i recive extremely low contentrations of Si (like 3-4 times lover). Is it because Si is volotised during sample preparation or ... ? (During the digestion period, vessels are closed, so nothing can escape the vessel. Before opening them i wait untill they reach 20C).
Now, in both cases i get high results. Here i am completely lost. Problem is, that in most cases P is being determined on wavelength of 179,..nm (and it is performed in vacuum). Since i don`t have any vacuum chamber, I have to do it on 214,...nm (on 213nm - i get negative conc.)
For FeCr it is extremely hard, not just because it has about 69% of Chrome, up to 9% of cabron, rest is Iron and other elements, but also because this product is very "different" every time (depending on the manufacturer, on carbon content, heavy metall content like Mo, Co, W etc. )
I would like to know, on what elements i should keep my eyes on, when i am preparing this matrix solution for FeCr, only those, that are very close to Si and P in wavelength?
What acids are better for P and Si determination on ICP-OES? (are there any buffer solution for P or Si, like LaCl3 or CsCl that could help be clear the noise)
Any advices in ICP configurations are also appreciated (since i am a beginner user).