In which of the following ways is the use of an infrared spectrophotometer fitted with an ATR sample advantageous over a beam‑through‑sample spectrophotometer? Select all answers that apply.
ATR allows for the use very small samples.
Beam‑through‑sample techniques have issues with nonpolar materials.
Beam–through–sample techniques require very expensive ZnSe sample holders.
Sample preparation and clean up of an ATR is simple.

ATR allows for the use very small samples.
Sample preparation and clean up of an ATR is simple.
This is because The ATR crystal is not degraded by the presence of water. The ATR method is advantageous because the ZnSe crystal sample holder :
Can accept very small quantities of solids or liquids.
Is not degraded by the presence of water.
Clean up is usually easy .
Beam-through-sample instruments use sample plates that are made from sodium chloride or potassium bromide and are easily damaged by contact with water; they must never be held with bare hands or washed with water.
The plates are also fragile and will easily chip or crack. Spectra of polar protic materials recorded on a beam-through-sample instrument may suffer from diminished resolution due to interactions between the sample and the salt plate.