QA/QC of sugars using the Agilent Cary
630 ATR-FTIR analyzer

Manufacturers who use sugars in their products need a ready-to-deliver, robust technology, free from system calibrations, that can test and accept or reject the sugar powder on the spot, ideally immediately on receiving the sample.

Small amounts of sugar samples were placed without weighing onto the sampling surface of the Agilent Cary 630 ATR-FTIR analyzer. The samples were pressed against the diamond crystal using the attached pressure clamp. A slip clutch on the clamp prevents overtightening.
Spectra were acquired in about 30 seconds by co-adding 64 spectra with a resolution of 4 cm-1. Each resulting spectrum was displayed on the computer screen along with its closest spectral analogue chosen from a spectral library database of sugar standards acquired using the Cary 630 ATR-FTIR analyzer and its MicroLab FTIR software.

All carbohydrate-based sugars possess strong and characteristic infrared absorptions between 1200 and 600 cm-1 attributed to C-O-H and C-O-C bonds. Protein-based sweeteners like thaumatin show unique absorption bands between 1700 and 1500 cm-1, which can be attributed to the amide I and amide II absorption bands belonging to the proteins. Artificial sweeteners also possess unique absorptions depending on their chemical structure.

Accordingly, the spectrum of a sugar can be easily assigned to a particular sugar class (carbohydrate, protein-based or artificial sweetener) and in most cases assigned with a high degree of accuracy to a specific sugar. Hence, when a new or unknown sweetener is
received, its spectrum can be compared to those stored in the database of previously recorded sweeteners, and its identity can be correctly established by the MicroLab FTIR software.

Excerpt from Agilent Technologies Application Note 5991-0786EN