IR sample IR sample preparationpreparation

for solid samplesfor solid samples

What is a mull?What is a mull?

a mull a suspension of solid sample a mull a suspension of solid sample in mineral oilin mineral oil

It is used to make a thin-film cell It is used to make a thin-film cell from a solid samplefrom a solid sample

Thin film IR cellsThin film IR cells

Salt (NaCl) discs are usedSalt (NaCl) discs are used To hold the sampleTo hold the sample So the holder won’t absorb infrared So the holder won’t absorb infrared

lightlight and only sample absorption is and only sample absorption is

detecteddetected

Sample preparationSample preparation

so so drydry the sample well the sample well because water etches the IR discsbecause water etches the IR discs and emulsifies with oil letting less light and emulsifies with oil letting less light

throughthrough

How do I make a mull?How do I make a mull?

grind grind the samplethe sample to a smooth to a smooth powderpowder add mineral oiladd mineral oil and mix itand mix it wellwell

What should the mull be What should the mull be like?like?

the mull the mull should lookshould look

and spreadand spread like soft butterlike soft butter

use clean glovesuse clean glovesto work with salt discsto work with salt discs

put on an extra put on an extra pair of glovespair of gloves

to protect cells to protect cells from anything from anything

aqueous on your aqueous on your regular glovesregular gloves

applying the mullapplying the mull

use a rubber use a rubber policemanpoliceman

to spreadto spread a thin layera thin layer on one discon one disc lower the 2lower the 2ndnd disc disc on top of the 1on top of the 1stst

and twist the discsand twist the discs to spread sample to spread sample

evenlyevenly

placing discs in cell placing discs in cell holderholder

use your fingeruse your finger to make a to make a

platformplatform in the cell holderin the cell holder

lower inlower in the NaCl discsthe NaCl discs ddoo not wedge not wedge

themthem

gentlygently place lidplace lid on topon top

slide into slide into positionposition

in light beamin light beam

close close sample sample compartmentcompartment

remove glovesremove gloves before usingbefore using keyboardkeyboard

to clean discsto clean discs

add a few dropsadd a few drops of chloroformof chloroform to each discto each disc

rub gently rub gently to clean offto clean off all traces of all traces of

samplesample ……

Keep discs dryKeep discs dry

replace replace in desiccatorin desiccator after cleaningafter cleaning ……