Brian C. Smith

May 01, 2021

Determining the components in a mixture can be a significant challenge in infrared spectroscopy, but spectral subtraction can help. We show the proper way to perform spectral subtraction, and the pitfalls to avoid.

March 01, 2021

One of the biggest practical limitations of infrared spectroscopy is its difficulty in analyzing mixtures. Infrared library searching can help, but it must be done right.

January 01, 2021

Integrating peak position, height, and width information is important to properly interpret infrared spectra. But do you understand why peak heights and widths vary? We explain.

November 01, 2020

Articles in this column have addressed five main areas: theory, functional groups containing the C-H bond, those containing the C-O bond, those with the C=O bond, and those with organic nitrogen compounds. Here, we review the concepts.

September 01, 2020

We review one final organic nitrogen functional group, representing explosive compounds. This is the nitro group, which requires a different set of interpretation rules.

May 21, 2020

Here we delve into the interpretation of another organic nitrogen compound, known as polyurethane, a ubiquitous polymer used for wood finishes and foam rubber.

March 01, 2020

Here, we continue our examination of the infrared (IR) spectra of organic nitrogen compounds with imides, which are a common chemical intermediate. IR can be used not only to identify imides, but also to distinguish between straight chain and cyclic imides. We explain how.

January 01, 2020

The N-H stretching and bending peaks can be used to distinguish primary, secondary, and tertiary amides and to ascertain protein structure. Here’s how.

November 01, 2019

Amides are an important functional group found extensively in polymers and proteins. There are three different families of amides. Here, is explained how to distinguish them using infrared spectroscopy.

September 01, 2019

The amine salt functional group contains ionic bonding, and is extremely polar, giving rise to a number of intense and uniquely placed peaks that are easy to identify for primary, secondary, and ter tiary amines.