\<<>V *hf<^y>^/ CONTENTS 



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General Part 



Page 



Introduction 3 



L The mode of occurrence of carotenoids in plants and animals. The detection 



and estimation of carotenoid pigments 5 



1 . Mode of occurrence in plants 5 



2. Mode of occurrence in animals 5 



3. Detection and estimation 6 



4. Colour reactions 7 



5. Spectroscopy 8 



6. Colorimetry 8 



7. Fluorescence spectra 8 



References 8 



II. The formation of carotenoids in plants and their physiological significance 10 



1. Mode of formation 10 



2. Function of carotenoids in plants 10 



3. Function of carotenoids in the animal organism 11 



a) Carotenoids as provitamins A 11 



b) Function of carotenoids in the visual process 16 



References 17 



III. The isolation of carotenoids 20 



1. Extraction of carotenoids 20 



2. Separation into hypophasic and epiphasic carotenoids 21 



3. Separation of the carotenoid mixtures of the two phases 23 



4. Crystallisation 28 



References 28 



IV. The chemical constitution of carotenoids 29 



References 37 



V. The cis-trans isomerism of carotenoids 38 



References 42 



VI. Methods of elucidating the constitution of carotenoids 43 



1. Determination of the number of double bonds 43 



2. Determination of side-chain methyl groups 44 



3. Determination of isopropylidene groups 45 



4. Determination of hydroxyl groups 45 



5. Determination of methoxyl groups 45 



6. Detection and estimation of carbonyl groups 46 



7. Determination of carboxyl groups 46 



8. Oxidation with permanganate and ozone 47 



9. Partial degradation of carotenoids with permanganate and chromic acid 47 

 10. Thermal degradation 48 



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