SUMMARY Equations have been developed for calculation of the total quantity of pigments consisting of chlorophyll a and its derivatives (chlorophyllide a, pheophytin a, and pheophorbide a) and of chlorophyll b and its derivatives (chlorophyllide b, pheophytin b, and pheophorbide b) in a mixture of these pigments in diethyl ether. Calculations are based on conversion of the chlorophylls and chlorophyllides into the pheophytins and pheophorbides, respectively, by the addition of hydrochloric acid and reading absorbances at two wavelengths. After removal of chlorophyllides a and b and pheophorbides a and b from the diethyl ether solution of the pigment mixture by 0.01N KOH, the quantity of each of the eight components listed above is estimated by indicated experimental and mathematical procedures.

This study has been made to establish the molar absorbance coefficients of the zinc and copper(II) complexes of the pheophytins and pheophorbides. Spectral curves and metal analyses have been madefor each of the four mentioned chelates of zinc and copper(II) following purification by chromatography. Chelation was accomplished with ease in aqueous acetone solutions of the respective pheophytins and pheophorbides. Thin-layer chromatography procedures, developed during this study, provided reliable indication of the purity of the complexes. Zinc and copper(II) salts and their solutions promoted rapid allomerization of the pigment during chelation. Molar absorbance coefficients are presented.

The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Experiment Station of the products named, nor criticism of similar ones not mentioned.

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complex f(Ph3P)2PdC03] tended to decompose in solution as it was formed, so with [(Ph3P)2PdCl2], the suspension was stirred only for about 15 min. However, the product obtained was always impure.Adduct of Carbon Disulfide with [(Ph3P)2Pt02]. Carbon disulfide was added dropwise to a solution or suspension of f(Ph3P)2-Pt02] (0.75 g) in ice-cold benzene-ether (5 ml/5 ml) until no further reaction was observed (usually 3-4 drops). The orange crystals formed were filtered off rapidly, washed with ice-cold ether, and dried in vacuo.The compound tended to decompose to the dithiocarbonate analog in solution but was quite stable when dry; yield, 0.75 g (about 90%). A similar procedure with [(Ph3P)2-Pd02] gave the dithiocarbonate directly, and oxygen was evolved on addition of CS2.