Iii. Chlorophyll Derivatives in Dsdp Leg 14, 20, 26, 27, and 29 Sediments

Electronic absorption spectra were obtained using a Beckman ACTA CIII ultraviolet-visible linear wavelength spectrophotometer and a Beckman DK-2 spectrophotometer. An Aminco-Bowman 8202 spectrophotofluorometer was employed for fluorescence measurements, and mass spectra were recorded using an AEI MS9 mass spectrometer equipped with a solid sample probe inlet system. The general procedure described for treatment of Leg 15 (Baker and Smith, 1973) and Leg 22 (Smith and Baker, 1974) cores was used in the analysis of Leg 14,20, 26, 27, and 29 sediment samples (Table 1). Core extracts yielding insufficient tetrapyrrole pigment for UV-visible analysis were treated with methane sulfonic acid (MSA) following the method of Baker (1969). The extract was treated with MSA (5-ml MSA for each gram of extract concentrate) in a ball mill containing 16 glass marbles, rolling at low speed for 4 hours at 105 ±5°C. After 4 hours, a mixture of 5 g of ice and 5 ml water per gram of extract was added with stirring. The solution (ca 50°C) was filtered and extracted with methylene chloride in a liquid-liquid extractor. The porphyrin was converted from the dication to the free base by treatment with sodium acetate (100 ml, 10% wt/v). These solutions were analyzed for free-base porphyrins by both emission and excitation spectrofluorometry. The porphyrins were then partitioned between the organic solvent and 6N hydrochloric acid and the acid solution analyzed for dication fluorescence. Sample size of the standard compounds was approximately 10 mg, and the instrument parameters were set at a moderate sensitivity level.