With special reference to their physical and photochemical properties and to analytical methods

Zscheile, F. P.

doi:10.1007/bf02872435

Cited by 23 publications

(6 citation statements)

References 208 publications

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“…In the absence of yellow pigments, the known ratio of heights of the absorption bands in the red and in the blue of the chlorophylls a and b will be altered when degradation products occur. (13~ 20) Likewise the presence of particularly brown products can be checked by measuring the ratio of the absorbancies in the red and in the green, pheophytins and pheophorbides showing a peak in the latter region.Ql) A third application, in which the extinction readings at the red peaks of the chlorophylls a and b are checked by a measurement at an intermediate wave length, will be discussed below.…”

Section: Extractionmentioning

confidence: 99%

THE QUANTITATIVE ANALYSIS OF CHLOROPHYLLS a AND b IN PLANT EXTRACTS

Bruuinsma¹

1963

Photochem & Photobiology

527

188

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Section: Extractionmentioning

confidence: 99%

THE QUANTITATIVE ANALYSIS OF CHLOROPHYLLS a AND b IN PLANT EXTRACTS

Bruuinsma¹

1963

Photochem & Photobiology

527

188

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“…A series of dilutions was then made from the stock acetone solution and the light transmission of each of these dilutions was measured on the photelometer as described by Petering, Wolman, and Hibbard (5). The chlorophyll content of each of the above solutions was calculated from the value obtained -Discussion Numerous workers (8,4,6,7) have discussed the disagreements in the reported spectroscopic values for the chlorophylls and the factors involved in chlorophyll degradation. It is to be emphasized that chlorophyll is not stable, and tends to form pheophytin as one of the first products of decomposition.…”

Section: Methodsmentioning

confidence: 99%

Calibration of Photoelectric Colorimeter for Determination of Chlorophyll Relation between Spectra of Standards and Accuracy of Analytical Results

Comar¹,

Benne²,

Buteyn³

1943

Ind. Eng. Chem. Anal. Ed.

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“…Errors in total carotenoid contents might differ among samples if the characteristic curves should vary considerably in relation to the wave length-sensitivity characteristics of the instrument employed. Factors applicable to the subject of methods were discussed by Zscheile (1941).…”

Section: Clhroinatographio and Detailed Spectroscopic Observations Onmentioning

confidence: 99%

CAROTENOID CONTENT OF CARROT VARIETIES AND STRAINS¹

Harper

Zscheile

1945

Journal of Food Science

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The carrot root (Daucus carota, L.) has been the source of material for much research on carotenoids and it serves as an important commercial source of carotene for experimental and nutritional purposes. Considerable discrepancy has been reported in the literature between the carotenoid content of carrots, as determined by chemical and physical methods and converted to provitamin A activities, and the actual potencies found by animal feeding experiments. This general problem has been reviewed recently by Graves (1942). It appeared possible that in some cases the analytical methods might be unreliable in that nonactive carotenoids were determined and calculated as provitamin A-active pigments. For this reason a spectroscopic study of carrot extracts and fractions was undertaken to provide a basis for more critical evaluation of methods.Very few carrot varieties and strains have bgen compared with respect to carotenoid content, and the contents of various parts of the root have not been studied quantitatively and spectroscopically to determine varietal differences. These problems are of considerable practical importance to those interested in the commercial use and value of carrots as a source of provitamin A. This paper reports results obtained in a survey of 16 commercial varieties and 18 special strains. EXPERIMENTAL PROCEDURE Extraction and FractioNation Methods:No method tried provided complete removal of the carotenoids in one acetone-hexane extraction (with Waring blender ) without preliminary blanching. The pigment remaining in the residue from unblanched carrots was not extracted by hexane or carbon disulfide but usually could be removed completely by a second acetone extraction. Samples of 10 to 15 grams fresh weight were extracted twice in a Waring blender with 125 ml. of acetone. The carotenoids thus removed were transferred to hexane by washing carefully with water three times. Carotenols2 were removed by washing the hexane solution successively with 90-per cent methanol, 20-per cent methanolic potassium hydroxide, and 90-per cent methanol (25 ml. each). The remaining methanol and alkali were removed with water and the solutions were dried with sodium sulfate, made to 100 ml., and stored at 4'C.(39.2"F.) for spectroscopic analysis. Journal Paper No. 164 of the Purdue University Agricultural Experiment Station. 'The term "carotenolJ' is used in this paper to denote the carotenoids extracted from hexane by 90-per cent methanol. The use of this term was discussed by Zscheile (1941). Such extraction should remove dihydroxy cornpounds but very little of the monohydroxy type, as shown by White and Zscheile (1942). 84

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With special reference to their physical and photochemical properties and to analytical methods

Cited by 23 publications

References 208 publications

THE QUANTITATIVE ANALYSIS OF CHLOROPHYLLS a AND b IN PLANT EXTRACTS

THE QUANTITATIVE ANALYSIS OF CHLOROPHYLLS a AND b IN PLANT EXTRACTS

Calibration of Photoelectric Colorimeter for Determination of Chlorophyll Relation between Spectra of Standards and Accuracy of Analytical Results

CAROTENOID CONTENT OF CARROT VARIETIES AND STRAINS¹

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With special reference to their physical and photochemical properties and to analytical methods

Cited by 23 publications

References 208 publications

THE QUANTITATIVE ANALYSIS OF CHLOROPHYLLS a AND b IN PLANT EXTRACTS

THE QUANTITATIVE ANALYSIS OF CHLOROPHYLLS a AND b IN PLANT EXTRACTS

Calibration of Photoelectric Colorimeter for Determination of Chlorophyll Relation between Spectra of Standards and Accuracy of Analytical Results

CAROTENOID CONTENT OF CARROT VARIETIES AND STRAINS1

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CAROTENOID CONTENT OF CARROT VARIETIES AND STRAINS¹