[lab_rat]

Hi there ppl, was wondering if you may be able to help...

I'm looking to use a CuSO4 solution as a quick check for the daily use of our UV/Vis spectro ie: i put the solution in at a certain wavelength and it gives me an absorbance. Use the same solution daily as a quick check to ensure the machine is functioning ok.

However im a complete noob and need some help...

What wavelength is optimal? What concentration of CuSO4 is appropriate?

Would like to use 420nm as most of our measurements are made around this wavelength , is it appropriate??

[enahs]

The easiest method would just to make a sample and run the full spectrum. See where the max absorption is and if it is near what you want. I mean, sure you can look it up, but with the application you are talking about, why not just do one quick run and see if it will work properly?

However, I would just suggest you get the manufacture and model of your Uv-Vis and go to their website and look for a standard kit. It will give you all the standard reagents and equipment to check for proper absorbance readings, stray light, wavelength and spectral resolution power, etc.

[lab_rat]

  Thanks enahs for your time, i appreciate the response. The UV/Vis spectro we have isn't a scanning one unfortunately, i would love an absorbance vs wavelength plot printed out beleive me, but I would have to do it by manually changing the wavelength each time...tedious and time consuming.

We are trying to avoid the expense of purchasing a kit, looking for something we can do in house with existing materials , CuSO4 being ideal as its stable for some time.

I have had a good google around looking for the info , but cant seem to find it in the myriad of info available.

[ARGOS++]

Dear lab_rat,

CuSO₄ is NOT a very wise Idea, because if your "bottle" with the blue crystals is not very new filled up, you will easily see some fine white powder on the rough edges, indicating that your  CuSO₄ has lost some crystal-water!!

So, the only Solution left:
Dry it, till all is white powder, AND keep it ALL TIME in the Exicator AND
under Vacuum!  -- Not very nice, at all!

The better solution:
  Buy a "certified Glass-filter", it's less cost as the procedure above over
  a small number of months!!
  Advantages:
   - "You" are stable all the time, - with warranty!
   -  You are, nearly, wavelength-independent!
   -  If You buy a Holmium Oxide Filter, You have at the same time an
       ABSOLUTE STANDARD for Wavelength-Calibration, too!

   Of cource also other Glass-Filters will do!
   A good source (Quality!): HELLMA

Good Luck!
                 ARGOS⁺⁺