Good day estimated reserachers,
I'm working on a validation for the ASTM 3230 Method which refers to the Salts in Crude Oil electrometric method and I'm constructing the calibration curve for different levels of known concentrations and their specific instrument readings. However, when doin the statistical analysis I need a CRM for certain parameters but I don't know if that's available.
psdt: we work in PTB concentration units and besides our blank (0PTB), we used level concentrations of 1PTB, 3PTB, 5PTB, 10PTB, 16PTB and 21PTB. Besides, the instrument readins are recorded in mA.
Thanks in advance! Wish y'all a good weekend.
I assume you can make your own calibration material by using appropriate salt in oil standards (as I think you're doing). You effectively have a 'CRM' by having a known mass in a known volume of oil and conducting the appropriate error balances. From what I understand (for example: http://www.stanhope-seta.co.uk/ssl_downloads/brochures/salt-in-crude-analyser.pdf) this is a conductometric test. Now I'm unsure what you mean by PTB. If it's parts per billion then I think your method is unsuited - seems to deal with up to 200 g/m3 approx. from the .pdf. There's even a YouTube video:
https://www.youtube.com/watch?v=GxNUTmJ467w
You could look for the NIST SRM 1818a Chlorine in Lubricating Base Oils:
https://www-s.nist.gov/srmors/view_detail.cfm?srm=1818A
Dear Alan, thanks for your response. We're indeed making our own calibration maerial standards for known concentrations of salt. I was just quite unsure about the real meaning of a CRM cause it's a common term for statistical comparison and analysis. But now I have a more clear idea, you're right by saying we have known masses and volumes; we'll be careful with error balances!
Oh, PTB stands for pounds per thousand barrel. A very common concentration unit to measure the pounds of chlorides in 1.000 barrels of oil in the oilfield. We use a different apparatus form that on the video but it's a very helpful complementary information. Every link is very useful. Thank you!
The 'standards' in the video seem to be electronic standards for conductivity as opposed to material standards for verification. The only caveat I would make from personal experience is that conductometric devices respond to all ions in the system not just chloride - for example sulfate (SO4 2-). BTW, SRM is the NIST trademarked terminology for certified reference material. They also have RM's that still contain a certificate - very confusing - but possibly not the same level of traceability.
Honestly I did not know about the existance of those electronic standards, but that's very interesting to know! Our material standards that we prepared include NaCl, MgCl2 and CaCl2 which are the common chlorides in the crude oil. Thanks for clarifying that last term! It's a very complete site with plenty of certificates! As always, very valuable contribution Mr Rawle.
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