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Specialty Chemistry Forums => Materials and Nanochemistry forum => Topic started by: Nadja on November 17, 2009, 06:41:55 AM

Title: Cleaning diamond crystal of an IR-ATR accessory.
Post by: Nadja on November 17, 2009, 06:41:55 AM

Hello,
I have a problem cleaning my diamond crystal for an IR-ATR accessory. The crystal looks visible clean, but when one runs an IR spectrum of it, it shows some traces of protein. I have tried washing it with water, ethanol, 0.8M sodium hydroxide, some special laboratory cleaning solution, and even with some HCl. But nothing seems to remove the protein. Unfortunately I don’t know what the protein is.
Does anyone have any ideas on how it might be cleaned?

Title: Re: Cleaning diamond crystal of an IR-ATR accessory.
Post by: gluedudeguru on November 17, 2009, 07:18:45 AM

If it is actually dirty, acetone usually does the trick, it is what i have always used.  Perhaps that this blib your seeing would be none existent with a proper background, especially if it looks clean.  We are sure your not refering to CO2 and water right?  What makes you think its protein? Does an IR/ATR even do protein?

ACETONE

Title: Re: Cleaning diamond crystal of an IR-ATR accessory.
Post by: Nadja on November 17, 2009, 07:25:53 AM

Yes we are sure its not water or CO2.
We see Amide I and Amide II bands. And when attempting to clean with NaOH and HCl we see protonation and deprotonation of carboxyl groups.
It feels like something formed a thin layer (film) on the crystal and is reacting with the solvents I'm trying to remove it with.

Title: Re: Cleaning diamond crystal of an IR-ATR accessory.
Post by: KeithM on November 17, 2009, 10:11:50 AM

Yes, I agree with the film theory, something has stuck on the surface. Try "polishing" it off. Use some cerium oxide, Cerox 1650 would be good, on a soft cloth.

What country are you in? I could send you a bit if you are in the UK

Title: Re: Cleaning diamond crystal of an IR-ATR accessory.
Post by: Nadja on November 17, 2009, 11:58:25 AM

Thank you, KeithM.

Unfortunately I'm in Stockholm Sweden. I'm sure that our department should have it somewhere, I'll ask around.

Title: Re: Cleaning diamond crystal of an IR-ATR accessory.
Post by: doc30 on December 03, 2009, 10:52:18 AM

We've had similar issues. Strong caustic won't hurt the diamond, but it might attack the adhesive holding it in place so be careful. How strong are the absorbance bands in the residue spectrum? You could clean with caustic, run a spectrum, clean again and run a second spectrum to see if the cleaning is removing any material. Can you look at the crystal under a low power microscope or magnifier and see if it is scratched or if there is a solid chunk you could scrape off with a microscope probe?

Title: Re: Cleaning diamond crystal of an IR-ATR accessory.
Post by: AlloyNB on December 23, 2009, 10:37:47 PM

You can polish a new clean Si crystal - it's not so difficult IMHO

Title: Re: Cleaning diamond crystal of an IR-ATR accessory.
Post by: Fleaker on December 29, 2009, 03:17:04 PM

If it's a diamond you're using, 70% perchloric acid takes protein off a treat.