Question

Why are quantitative analytical methods based on NIR radiation often more precise and accurate than methods based on mid-IR radiation?

Short answer

The quantitative analytical methods based on NIR radiation are more precise and accurate because these methods reduce the time, the detection limits are on the order of 0.1% and the use of both diffuse-reflection and transmission measurements makes it more accurate and precise.

Step-by-step solution

Step 1. Given information

Give the reason for more precise and accurate quantitative analytical methods based on NIR radiation than methods based on mid-IR radiation.

Step 2. Explanation

IR Spectroscopy is an important tool used to determine the structures of organic compounds. The mid-absorption region of the IR spectroscopy is called a functional group region. The range of the functional group region lies between 2 to 20 µm.

NIR Spectroscopy is a spectroscopic method that uses the region of near-infrared of the electromagnetic spectrum in the range of 770 nm to 2500 nm or $13000{\mathrm{cm}}^{-1}-4000{\mathrm{cm}}^{-1}$.
The NIR spectroscopy is used for the quantitative determination of organic matter like proteins, fats, and hydrocarbons of low molecular mass.

NIR radiation is more precise and accurate due to the following reasons:
- It reduces the time required to determine the structure of the compound and to perform the analysis.
- In the NIR region, the detection limits are on the order of 0.1 % and the molar absorptivities of the bands are low.
- The use of both diffuse-reflection and the transmission measurements makes it more accurate and precise.