| Multiple organic acids content accounted for12%-16%of dry matter weight in tobacco. Among them, the three main multiple organic acids that malic acid, citric acid and oxalic acid account for70%-80%of total organic acids content in tobacco leaves. Citric acid and malic acid is the intermediate products of carbohydrates into nitrogen metabolic. Its also the composition of the Krebs cycle of sugar, protein, fat and other biological macromolecules intermediate metabolic pathways of mutual transformation between the components. Malic acid and other acids are feed ingredients in some cigarette formulation. Therefore, quantitative analysis of volatile organic acids in tobacco is of great significance to the quality evaluation and leaf formula. In this thesis, a method for determination of multiple organic acids in tobacco by high performance liquid chromatography (HPLC) was developed, and applied it to study the effect of multiple organic acids on different fertilizer, different producing areas, different light seeding in tobacco. The main results are summarized as follows:A method for simultaneous determination of oxalic acid, malic acid, citric acid, lactic acid and succinic acid in tobacco leaf by high performance liquid chromatography (HPLC) was established. The results showed that the recoveries reached more than85.37%by phosphorous acid extracting multiple organic acids with water bath of80℃, heating30min. The multiple organic acids in tobacco were well separated and determined with a Welch Ultimate, AQ C18column(250mm*4.6mm,5um), by using KH2P04(0.02mol/L; pH3.0) and methyl alcohol as mobile phase at the detection wavelength of215nm, with relative standard deviations of0.58%-1.99%and the limits of detection0.03-0.80μg/mL.Therefore, high performance liquid chromatography is an effective method for determination of the multiple organic acids in flue-cured tobacco with precision, high detection sensitivity, and high repeatability.The multiple organic acids content in flue-cured tobacco with dressing fermented cake or no-fermented cake (rapeseed meal, dregs of beans, cotton dregs, camellia pancake) was studied by using the fore mentioned method by HPLC. It showed that, among the treatment with cake fertilizer, the multiple organic acids total content in flue-cured tobacco all are more than of CK, but, Different kinds of cake processing for tobacco, the main non-volatile organic acids content are different. Their oxalic acid are obviously higher than that of ck(6.33mg/g); their malic acid are significantly higher than that of ck(34.91mg/g); in addition to the rapeseed meal processing, the citric acid content with other cakes processing were higher than that of ck.The multiple organic acids content in flue-cured tobacco from different areas was studied by using the fore mentioned method by HPLC. It showed that, the main non-volatile organic acids content are different from tobacco producing area and its stalk position. The oxalic acid content of Sanming, Fujian province is the highest, the citric acid content of Sanming and Baoshan is the highest, followed by that of Liangshan and Weining, and that of Chenzhou and Xuchang are relatively low. Malic acid content showed great difference in decreasing order of Henan, Yunnan, Guizhou, Sichuan, Hunan and Fujian. Moreover, malic acid and citric acid content have trended more with the decrease of leaves, but opposite for oxalic acid that it have trended lower with the decrease of leaves.The multiple organic acids content in flue-cured tobacco from different light seeding in tobacco was studied by using the fore mentioned method by HPLC. It showed that the multiple organic acids content in tobacco with the treatment of complex light of red LED and blue LED(3:1) is more than that of others, and the main non-volatile organic acids content are different from tobacco varieties. K326have great ability to respond than Yunyan87. The malic acid content of K326and Yunyan87with red LED seeding treatment is significantly higher than that of ck, and the citric acid content of K326is reduced, but it showed no apparent difference to the citric acid content of Yunyan87. |
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