Paperboard Wet End Additive Sorption Mechanics and Chemical Retention Verification
Verify paperboard wet end additive retention using dynamic drainage jars and extraction GC-MS to ensure food contact compliance and prevent converting failures.
Dumas Combustion
Elemental Method
Quantitative thermal oxidation measures total organic nitrogen within cellulose substrates by converting bound compounds into nitrogen gas through high temperature pyrolysis. Dumas combustion operates at temperatures exceeding nine hundred degrees Celsius inside a sealed quartz tube where a constant oxygen flow ensures complete oxidation. Interfering gases such as carbon dioxide and water vapor are scrubbed from the gas stream before quantification occurs through thermal conductivity detection.
Mill laboratories apply this procedure to specialty papers and coated board grades to verify protein based additives and wet strength resin content.
Nitrogen Conversion
Total nitrogen values obtained from thermal oxidation convert directly to protein percentages through specific multiplication factors depending on the botanical or synthetic origin of the pulp. Cellulose pulps derived from recycled fractions require distinct correction factors because residual urea formaldehyde resins alter the baseline nitrogen signature. Analytical technicians maintain strict calibration schedules using pure reference compounds such as EDTA to ensure mass recovery remains within acceptable tolerances during continuous shifting production cycles.
Board converters rely on these verified nitrogen metrics to demonstrate compliance with food contact migration limits established for paper packaging materials.
Oxidation Threshold
Complete destruction of refractory organic matter demands precise oxygen dosing because insufficient oxidant supply leaves unburned char residues inside the combustion zone. Excess oxygen floods the thermal conductivity detector and distorts baseline stability during the final integration phase of the chromatographic analysis. Sample mass must remain small enough to prevent localized oxygen depletion within the combustion reactor while large enough to represent inhomogeneous fibrous matrices.
Analytical repeatability drops significantly when particle size exceeds the mill pulverization standard required for dense multilayer laminated paperboard structures.