Total Nitrogen Determination in Sugar and Starch by Catalyst-Free High-Temperature Combustion and Chemiluminescence Detection Application Note · multi EA 5100

Introduction

Saccharides, often commonly referred to as sugars and starch, are important ingredients in food production, e.g. in soft drinks, confectionery and others. The possibility of easily and quickly converting them into alcohol by fermentation processes also makes them interesting for the chemical industry and for fuel production (e.g. bio ethanol, E10).

Sugars can be produced in many ways, either directly by refining processes from natural sources (sugar cane, beet root) or industrially by enzymatic hydrolysis of starch (corn, potato) with amylase. Depending on the origin and type of raw materials and the production process, the final products can contain different amounts of nitrogen. In raw materials the present TN content results from natural (plant metabolism, minerals) or artificial sources (fertilizers), but it can also be incorporated into the product during the production process. No matter where they come from, N-compounds are undesirable due to the lower quality of the final products (purity, formation of byproducts). But also during the refining of sugar from sugar plants, increased nitrogen content has a negative effect on the ratio between molasses and sugar. That is why the determination of the parameter TN is an integral part of process control and quality assurance. Due to the widely varying concentrations, down to trace contents, elemental analysis coupled with highly sensitive chemiluminescence detection has proven to be the best suited technique for this challenging task.

Oxygen-rich aliphatic or polycondensed cyclic materials such as mono- (dextrose, maltose), oligo- or polysaccharides (starch) tend to decompose thermally when being heated. This severe reaction releases lighter molecules such as water and short-chained hydrocarbons under smoke formation, while the remaining materials form unsaturated pyrolysis products which are condensed even higher. This is a real challenge for analytical technology. A controlled and complete conversion, which is essential for reliable analytical results, becomes impossible.

Flame sensor technology facilitates time and matrix-optimized decomposition. The smart sensor used in the multi EA 5100 ensures the quantitative combustion of all components without splattering during melting, fuming off, explosive ignition or soot formation. This avoids outliers or TN results that are too low as well as a contamination of the analysis system.