What is NIR Spectroscopy?

Near Infrared (NIR) Spectroscopy is an analytical technique used across a wide range of sectors and industries. From profiling the chemical and physical properties of raw materials used for steelmaking to determining the protein and fat contents of food products, NIR can be used to analyse most solid, liquid and slurry samples.

Below, we take a closer look at the basics of NIR Spectroscopy, how it works and why it’s such a valuable analytical tool.

The near-infrared region

As the name suggests, NIR Spectroscopy focusses on the near-infrared region of the electromagnetic spectrum. This falls between 780 nm and 2500 nm, just outside the range normally visible to the human eye.

Light in the near-infrared region interacts with chemical compounds present in the sample in different ways, with special instruments used to measure absorbance and transmittance patterns. Data is used to identify and quantify the unique characteristics of a sample.

The origins of NIR Spectroscopy

German-British astronomer William Herschel is credited with the discovery of the near-infrared (NIR) region of the electromagnetic spectrum, though it wasn’t until the late 1960s it was developed into an analytical technique. Since then, NIR Spectroscopy has emerged as one of the most useful tools in a scientist’s arsenal. Today it’s used across a wide range of industries, including pharmaceuticals, chemical products, agriculture and food.

The benefits of NIR Spectroscopy

• Easy to use - NIR Spectroscopy is relatively straightforward to operate
• Minimal sample preparation – quick and easy
• Fast analysis – results in as little as 10 seconds
• Capacity for simultaneous results across a range of parameters using a single sample
• Accurate and reliable
• A cost effective analytical technique – one researcher can analyse hundreds of samples per day

Applications for NIR Spectroscopy

With so many benefits to offer, it’s no wonder NIR Spectroscopy is one of the most popular analytical techniques used by modern scientists. In the agriculture industry, NIR Spectroscopy is being used to improve soil management practices. Spectral data is used to analyse the water-carrying potential of soil and help farmers develop irrigation strategies. In the forestry sector, NIR Spectroscopy is paired with chemometrics methods to identify wood species.

“The chemical composition of wood is very complex. Many experimental studies have shown that cellulose, hemicellulose, lignin, and other organic molecules (such as glucose, fructose, pinitol, sorbitol, and inositol) are contained in wood, and these substances all have spectral response in the NIR region,” reads a report published in the journal Spectroscopy Supplements.

NIR Spectroscopy offers incredible insight into the chemical and physical properties of a sample, however it’s not the only analytical technique available to scientists. From X-Ray Spectroscopy to Atomic Absorption Spectroscopy (AAS), we take a closer look at some alternative methods in our complete guide - ‘What Are the Different Types of Spectroscopy?’