Conducted by Jerry Workman, Ph.D.
co-author of the popular Spectroscopy series
Statistics in Spectroscopy and Chemometrics in Spectroscopy

Near infrared spectroscopy is used for many applications where multicomponent molecular vibrational analysis is required in the presence of interfering substances, such as high moisture content, or when sampling is constrained to in situ conditions. The near infrared spectra consist of overtones and combination bands of the fundamental molecular absorptions found in the mid-infrared region. Near infrared spectra consist of generally overlapping vibrational bands that are non specific and non-resolved. Spectra measured using this wavelength region also contain information related to the optical and physical properties of many samples. The use of chemometric mathematical data processing can be used to calibrate for qualitative or quantitative analysis despite these apparent spectroscopic limitations. Traditional near infrared spectroscopy was used in agricultural product analysis for lignin polymers (2270 nm), paraffins and long alkane chain polymers (2310 nm), glucose based polymers such as cellulose (2336 nm), amino acid polymers as proteins (2180 nm), carbohydrates (2100 nm), and moisture (1440 and 1940 nm)

The dominant near-infrared spectral features include the methyl C-H stretching vibrations, methylene C-H stretching vibrations, aromatic C-H stretching vibrations, O-H stretching vibrations, methoxy C-H stretching, and carbonyl associated C-H stretching. In addition, N-H from primary amides, secondary amides (both alkyl, and aryl group associations), N-H from primary, secondary, and tertiary amines, and N-H from amine salts predominate near infrared spectral features of polymers and organic compounds. The positions of many harmonics and combination bands can be accurately assigned and assist the spectroscopist in applying standard spectroscopic techniques or in verifying chemometric results. This presentation will describe methods for interpretation and use of near infrared spectra for applications in natural products, pharmaceuticals, hydrocarbons, polymers and rubbers, and other materials.

This audio seminar CD is presented by Jerry Workman, a worldwide expert on spectroscopy.

A detailed outline follows below.

Bonus Article:
All Participants will receive:

• NIR Correlation Chart

How to Interpret Near Infrared Spectra for a Variety of Applications

Part I
The Framework for Near Infrared Spectral Interpretation

Part II
Short-wave Near Infrared and Applications

Part III
Spectroscopy in the Near Infrared Region

• Natural Products
• Pharmaceuticals
• Hydrocarbon Analysis
• Polymers and Rubbers
• Other Applications

Part IV
NIR Spectral Measurements

• Relative intensities of C-H stretch bands for infrared and the various NIR overtone regions
• Relative measured peak heights for toluene aromatic C-H stretch
• Relative measured peak heights for asymmetric C-H methylene stretch from n-decane
• Relative measured peak heights for asymmetric C-H methyl stretch from trimethyl pentane

Part V
Near Infrared Sprectra-Structure Assignments

• Basic structures of model compounds (where Me represents a single methyl group as -CH3)

4th (5n) overtone and 4n combination bands (C-H)

• Aromatic C-H stretching 710 nm - 720 nm
• Methyl C-H stretching 744 nm - 750 nm
• Methylene C-H stretching 760 nm - 766 nm
• Methyl C-H stretch and bending combination at 800 nm - 820 nm
• Methylene C-H stretch and bending combination at 820 nm - 845 nm

3rd (4n) overtone and 3n combination bands (C-H)

• Aromatic C-H stretching 875 nm - 881 nm
• Methyl C-H stretching 896 nm - 916 nm
• Methylene C-H stretching 911 nm - 936 nm
• Methyl C-H stretch and bending combination at 1010 nm - 1030 nm
• Methylene C-H stretch and bending combination at 1030 nm - 1050 nm

2nd (3n) overtone and 2n combination bands (C-H)

• Aromatic C-H stretching 1100 nm - 1144 nm
• Methyl C-H stretching 1190 nm - 1195 nm
• Methylene C-H stretching 1135nm - 1215 nm
• Methyl C-H stretch and bending combination at 1375 nm - 1400 nm
• Methylene C-H stretch and bending combination at 1410 nm - 1440 nm

1st (2n) overtone C-H stretch bands

• Aromatic C-H stretching 1650 nm - 1682 nm
• Methyl asymmetric stretching C-H 1690 nm - 1695 nm
• Methyl symmetric stretching C-H 1700 nm - 1705 nm
• Methylene asymmetric stretching C-H 1725 nm - 1730 nm
• Methylene symmetric stretching C-H 1755 nm - 1765 nm

 

Part VI

• The combination region of the fundamental (n) vibrational bands of C-H
• Methylene C-H asymmetric stretch and bending combination at 2300 nm - 2320 nm
• Methylene C-H symmetric stretch and bending combinations at 2340 nm - 2360 nm
• Methyl 2nd (3d) overtone C-H bending

Part VII

• A complex example of spectra-structure assignments (8 cm-1 resolution spectra)

Part VIII

• NIR Spectra-Structure Correlation References

Jerry Workman, Ph.D.

Jerome (Jerry) J. Workman, Jr. is the Director of Research, Technology & Applications Development for Molecular Spectroscopy & Microanalysis at the Thermo Electron Corporation. He was formerly Chief Technical Officer and Vice President of Research & Engineering at Argose Inc., Senior Research Fellow at Kimberly-Clark Analytical Science & Technology, and Principal Scientist at Perkin-Elmer.

In his career, his focus has been on multiple aspects of spectroscopy, including fluorescence, near infrared, infrared, ultraviolet-visible, Raman, and process spectroscopy as well as chemometrics. He is co-author of the popular Spectroscopy series Statistics in Spectroscopy and Chemometrics in Spectroscopy which have published over 100 columns since 1986. He has authored multiple books, several hundred scientific papers, commercial software programs, and U.S. and international patents. In 2002 he was the recipient of the Eastern Analytical Symposium Award for Outstanding Achievements in the Field of Near Infrared Spectroscopy, the ASTM International Award of Merit, and IBC International Scientist of the Year.

Dr. Workman is a Fellow of the American Institute of Chemists, the American Society for Testing and Materials International, and the Royal Society of Chemistry (U.K.). He is also a Chartered Chemist (CChem) of the Royal Society of Chemistry (England) and a Chartered Scientist of the Science Council (UK/Europe). He has served as Chair of the Industrial Advisory Board for the Center for Process Analytical Chemistry (CPAC) at the Univ. of Washington; The Council for Near Infrared Spectroscopy; and is immediate past Chairman of ASTM Main Committee E13 on Molecular Spectroscopy and Chromatography. He has been a graduate advisor for several institutions and graduate students. He serves on the U.S. National Academies NRC Panel for assessment of NIST programs. He has degrees in natural sciences, genetics, biological chemistry and business. More biographical details may be found in Who's Who in America.