IR sample preparation

1
IR sample preparation

• for pure liquid samples

2
What is a thin film cell?

• a thin film cell
• is a drop of pure liquid sample
• sandwiched between salt (NaCl) discs

3
Thin film IR cells

• Salt (NaCl) discs are used
• To hold the sample
• So the holder wont absorb infrared light
• and only sample absorption is detected

4
Sample preparation

• so only dry (anhydrous) samples are used
• because even traces of water etch the IR discs
• affecting the path length of light
• and the optical quality of discs

5
use clean glovesto work with salt discs

• put on an extra pair of gloves
• to protect cells
• from anything aqueous on your regular gloves

6
Preparing salt discs

• Slide off
• The top of the
• Desiccator
• Remove
• Salt discs

7

• replace
• desiccator cover
• immediately
• remove discs
• from sleeves and
• rest on kim wipe

8
to clean discs

• add a few drops
• of chloroform
• to each disc
• rub gently
• to clean off
• all traces of sample

9
adding sample

• add one or two drops
• of sample
• in the middle
• of the 1st disc
• lower
• the 2nd disc
• on top as shown
• to spread sample
• evenly

10
placing discs in cell holder

• use your finger
• to make a platform
• in the cell holder
• lower in
• the NaCl discs
• do not wedge them

11

• gently
• place lid
• on top
• slide into position
• in light beam

12

• close
• sample
• compartment
• remove gloves
• before using
• keyboard

13
to clean discs

• add a few drops
• of chloroform
• to each disc
• rub gently
• to clean off
• all traces of sample

14
Keep discs dry

• replace
• in desiccator
• after cleaning