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Sample preparation of sunscreen for use in UV-Vis

  1. Mar 13, 2015 #1
    I am currently doing a project on sunscreen analysis using UV Vis Spectroscopy and I am using slides to prepare my samples for measurement.My setback is how to make the samples uniform so as not to affect the transmittance and absorbance results.Any ideas on how i can successfully makes all the samples on the slides even and uniform?
     
  2. jcsd
  3. Mar 13, 2015 #2

    Quantum Defect

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    One possibility is to use a bit of shim material (something thin) that you can clamp between two optical flats. If you have shim material that is cuttable, it would be easy to cut out a small section for your sample, put the shim on top of the bottom slide, place the sample in the cut-out, and place the top slide on top. Hold the whole thing together with tape, rubber band, binder clip, etc. Yu may need to make a channel for the excess sample to squeeze out. You can run a blank the same way.
     
  4. Mar 13, 2015 #3
    Hello:
    Why do you not dilute the sunblock in methanol and then read it in a quartz cuvete. That way you would not have to worry about the thickness of the film.
     
  5. Mar 24, 2015 #4
    Thank you guys for the input.Used a cuvette and got my results.Another question is that the data collected is in excel format.I would like to plot graphs for all measurements in matlab but the roadblock is that its a lot of data since I did nine samples.I was told that i can use Singular Value Decomposition to reduce the dimensions.Anyone know how i can apply the SVD in my data in excel and also plot the graphs in matlab?
     
  6. Mar 24, 2015 #5

    Borek

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    Why don't you export the excel data as CSV?
     
  7. Apr 17, 2015 #6
    @Borek please guide me on how to do that.I would highly appreciate that.
     
  8. Apr 17, 2015 #7

    Borek

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    Use Save as command and select CSV (comma separated values) as the output format. This is a simple text format with a single line being a row of the spreadsheet.
     
  9. Apr 17, 2015 #8
    And how do i do singular value decomposition on the values in matlab?
     
  10. Apr 17, 2015 #9

    Borek

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    Sorry, no experience in matlab.
     
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