[wdonovan]

Hi all. First time here. I am trying to semi-retire an aging DCP (like ICP) spectrometer I use for metal alloy analysis. Budget is a strong consideration and the throughput is small (3 to 6 per week). Current dilutions bring elements into approx 10ppm to 100ppm range with a couple of exceptional tests going to 250ppm. I could dilute 1:10 further without losing precision. Mostly tool steels & also a little alum and Cu alloys so El's of interest are: Cr, Mo, V, W, Ni, Co (for steels), Al, Fe, Sn (for bronzes), Cu, Mg, Mn, Si, Fe (for aluminums). My question is about the possibilities of using an atomic absorption spectrometer, particularly graphite furnace.

I can't dilute into ppb range. I would lose precision severely but in my searches I have found an GFAA that I can afford and I was told by a spectrometer tech that I could use an AAS as an AES by removing the lamp and measuring emission. I did not think to ask if he was specifally talking about a flame machine or if this is possible on a GF unit. If I could use a GFAA it would make life beautiful again. I am aware of the added analysis time and don't have a problem with occasional double-dilutes for high and low concentrations. Is this possible? Is there enough heat in a graphite furnace to emit from concentrations in the 10 to 100ppm range? I could dilute to 2x this concentration if needed. Disclaimer: I am not a chemist nor chem engineer, just a lowly mech engineer that is pitted against the task of qualifying incoming metals and a little reverse engineering and forensics. I have an SEM with EDX to determine El's of interest in these cases.

[enahs]

I use a Perkin Elmer AAnalysts 800 for man of the metals you talk about all the time, from the ppb range up to 100 ppm. The detector is still perfectly linear at 100ppm, so it could go higher. I would contact the manufacture directly of the AA's with your exact specification requirements and exactly how you want to use it.


Even if you do not want to buy new and go used, just calling all the major companies and asking about which AA would fit your needs you will quickly get help and advice very fast.

[wdonovan]

Thanks for the reply. Do you use the furnace or is this range in flame mode? The unit I am looking at does not have a flame option and I understand that the furnace yields a dynamic range of at least an order of magnitude less than flame.

[wdonovan]

Got the answer from P/E... Emission needs flame. No can do with furnace. Thanks to those who helped.

[Grundalizer]

I find this interesting because in my senior Instrumental Analysis class, we just finished a lab on Flame AA.  We used Acetylene Air, and I found that machine to be so cool!  Our standards ran from 0.01ppm to 5ppm, and our teacher said we could measure ppb but I wasn't paying attention to what she said.

How does the Inductivley coupled plasma / graphite furnace change your  detectable limit range?  Does it?  Is it just all about temperature...or certain metals work better with certain ionization technique?

I'm interested to know, thanks.

[JGK]

I find this interesting because in my senior Instrumental Analysis class, we just finished a lab on Flame AA.  We used Acetylene Air, and I found that machine to be so cool!  Our standards ran from 0.01ppm to 5ppm, and our teacher said we could measure ppb but I wasn't paying attention to what she said.

How does the Inductivley coupled plasma / graphite furnace change your  detectable limit range?  Does it?  Is it just all about temperature...or certain metals work better with certain ionization technique?

I'm interested to know, thanks.

Using our ICP-oes machine, the detection limits are 2 - 3 orders of magnitude lower (depending on the element being analyzed). Also, you don't have to switch lamps for each element and can analyze for multiple elements simultaneously.

[Grundalizer]

What sort of price does someone charge for metal testing like that?  How much does an old/used Graphite Furnace AA go for?

I emailed a company trying to get quotes on two older machines and they never responded. 

I live near an old coal plant and I've seen interest in the community for heavy metal testing in their soil, because they are unsure of whether they can grow vegetables.

I've also heard directly from people that they send out samples to companies, which I assume charged more than $100.00.

Just wondering if a machine like that (if you could get it refurbished/used/cheap) would pay itself off in months, years, tens of years.  Obviously depending on throughput.

[wdonovan]

Wow. This thread went a lot further than I thought it would. I wound up with a radial torch ICP and I'm glad I did. The AAS would have added needless work with no real benefits for my application (incoming metal alloy verification, reverse eng'g and forensics). It would have had the plus of being well-suited for a verrrry occasional ppb run.
To Grundalizer - ICP or DCP brings high end of working range into the 500 ppm or higher region (for my elements of interest). I analyze a lot of alloys made up of of 5% to 10% elements of interest.
To JGK - My understanding has been that ICP-OES det limits are 2 - 3 orders of mag. higher, not lower than AAS.
Hmmm. Interestingly, one of my posts got mysteriously attached to another poster. The post marked "Posted by: keviavuz78" was actually mine.