Tobacco Starch And Total Nitrogen Quantification By NIR And FTIR

Starch is a kind of important compounds in tobacco. On one hand, it influence theburning rate and the completeness of combustion of tobacco, on the other hand, the starch willgenerate Irritant,parching smell and offensive odor when burning. It has a bad effect on tastequality. Nitrogen mainly exist in the protein and nicotine which also has an important effecton the quality of tobacco. At present the determination methods of total nitrogen and starchcontent in tobacco often are chemical methods. The process is complex and it is difficult toquantify rapidly. This paper attempts to establish a rapid and accurate method for a rapidquantifying of starch and total nitrogen in tabacco.The feasibility of starch and total nitrogen content quantification by FTIR and FT-NIRwas studied in the thesis, by which a rapid quantification method for starch and total nitrogenin tobacco cluld be established. The main results are as follows.（1） The iodine chromogenic method, which was modified in our study, was applied todetermination of the starch content in tobacco, the variation coefficient was2.11%, standardaddition recovery rate is97.2%on average. Compared with the perchloric acid extraction, itwas shown that the modified iodine chromogenic method is simple,rapid, and the accuracy ishigher. The starch content in50tobacco samples were assayed by this method.（2）The near infrared spectrum data of tobacco samples was collected by Near InfraredSpectroscopy （NIRS）. The NIR spectra were associated with the value of chemical method byOPUS/QUANT27.0software. Regression models of starch and total nitrogen content intobacco were established.The R²of models’ cross validation respectively are0.9177and0.9014, the corresponding RMSECV of models’cross validation respectively are0.296and0.511. The models were examined by unknown samples.The R²of models’ external inspectionrespectively are0.9539and0.9120, and the corresponding RMSEP are0.200and0.477.Internal cross inspection and external validation were proved that FT-NIR analysis had highaccuracy.（3）FTIR method was applied on the determination of starch content in tobacco, the resultshowed that the area of C-O-H shock absorption peak(1340nm^-1) has high correlation withthe content of starch. The correlation between the FTIR peak area and corresponding value of chemical composition by OPUS/QUANT17.0analysis software was obtained. In the study oftotal nitrogen content, The relevance between individual characteristic peaks and totalnitrogen content were not significant. But the linear regression between the total area ofcharacteristic peaks and the nitrogen content is statistically significant. The determinationcoefficient is0.98. The unknown samples were used for models examination and the meanvariation coefficient were2.918%and2.014%respectively. It preliminarilly indicated thatthis method could be used for determination of starch and total nitrogen content in tobacco.