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analysis is its inability to analyze high molecular weight organosilicons. The second problem in either techniq ue has been the choice or standards, since sensitivities may vary greatly and the composition or a mixture rrom the natural environment will probably be very complex. METHOD I (GAS CHROMATOGRAPHY) (Morrow et al. 1969) Column or 2 m x 0.6 cm (od) stainless steel packed with 20% SE-30 on 30-60-mesh Chromosorb W. Use helium carrier gas. METHOD 2 (HIGH PRESSURE LIQUID CHROMATOGRAPHY) (Cassidy et al. 1976) Place the eluted or extracted material in a reverse-phase liquid chromatography system which has a 30 cm C I8 fL-Bondapak column. Elute with 15% (V IV) water/methanol mixture at 2.5 ml/min. V. Detection Pipe material rrom either system via II.!" stainless steel tubing into an atomic absorption spectrometer. Wavelength 251.6 nm; nitrous oxide/acetylene reducing flame. Notes: (a) Freq uent calibration is necessary to allow ror flame changes. (b) Remove build-up orcarbon deposit on burner head to prevent baseline shirt. (c) Method 2 - The atomic absorption spectrometer may be insensitive to minor changes in solvent composition; however, large changes will alter the ruel/air ratio, and thus the atomization efficiency. Gradient elution may prove very difficu I t, ir not im possible. (d) Chemical Abstracts Service is publishing a special biweekly series on this subject: CA Selects Organosilicon Chemistry, Chemical Abstracts Service, Ohio State University, Columbus, Ohio, 43210. This may be consulted ror the current state orthe art. References CASSIDY, R. M., M. T. HURTEAU. 1. P. MISLAN. AND R. W. ASHLEY. 1976. Preconcentration of organosilcons on porous polymers and separation by molecular-sieve and reversed-phase chromatography with an atomic absorption detection system. 1. Chromo Sci. 14: 444-447. MORROW, R. W. , 1. A. DEAN , W. D. SHULTZ. AND M. R. GUERIN. 1969. A SILICON-SPECIFIC DETECTOR BASED ON INTERFACING A GAS CHROMATOGRAPH AND A FLAME EMISSION OR ATOMIC-ABSORPTION SPECTROMETER. 1. CHROM. SCI. 7: 572-575. SMITH, A. L. (ed.) 1974. Analysis of silicones. John Wiley and Sons LId., New York, N.Y. 407 p. 6.22 Total Organic-Inorganic Carbon Inorganic, organic and total carbon measurements are not included in the list orscheduled items in the Ocean Dumping Control Act. These data are orten very userul in evaluating both the physical and chemical analyses and aid in predictions or the rate or dredged materials when dumped into the ocean. For this reason, a procedure is included here. I. Theory The technique involves oxidation or all carbon in the sediment and measurement or the resultant carbon dioxide. Another part or the sediment is treated with acid to dissolve carbonate (inorganic carbon), and the material is again oxidized to carbon dioxide. The second rraction is taken to represent organic carbon. However, there have been many suggestions that some or the more labile components or the organic rraction are also destroyed by the acid treatment. Analysis by this method is reasonable ror total carbon; however, determination orinorganic/organic rractions may be only semiquantitative. n. Instrumentation Oxidizing rurnace Crucibles or heating tubes appropriate to instrument used 65
High-purity gases Catalysts and standards suggested by manufacturer's handbook III. Procedure (based on Pocklington and Hagell 1975) (I) Weigh out the manufacturer's recommended quantity of dried sediment (50-60°C, overnight) in the appropria te crucible or combustion tube. (2) Set up flow rate of gases and other instrument parameters as per manu facturer 's instructions. (3) As per manufacturer's instructions, determine the total carbon content of the sa mple. (4) Destroy inorganic carbon (carbonate sediments) by placing known weight of sediment in porcelain crucible adding 10% hydrochloric acid (to cover sediment) and heat covered dish in shallow water bath at 60°C for 2 h. Additional acid may have to be added at end offirst hour. Take care on addition' (5) Dry sediment from (4) in oven a t 60°C a,nd redetermine carbon con ten t as for the first three steps. (6) The carbon con tent of (3) represen ts the " total"; the carbon con ten t from (5) represents the "organic fraction." The difference in carbon contents represents the" inorganic carbon fraction." Note: The acidification step for destruction of inorganic carbon is the step most likely to cause problems with the determination of the values for inorganic-organic carbon. It is suggested that reagent grade hydrochloric acid be used and that the sample not be washed after acidification. IV. Alternative Procedure An alternative procedure involves the destruction of organic carbon in a low-temperature asher (oxygen plasma). Total carbon is determined as for steps ( I ) to (3) above. Another section of the sam pie is fully oxidized in a low-temperature asher to destroy the organic fraction. The inorganic carbon fraction is then determined by the same procedure as for total carbon (steps 1-3). The difference between the two carbon contents represents the organic carbon content; however, it should be noted that very refractory organic com pounds may not be oxidized in the low-tern pera ture asher. References POCKLINGTON. R .. AND G . T. HAG ELL. 1975. The quantitative determination or organic carbon. hydrogen. nitrogen and lignin in marine sediments. Bedrord Ins!. Oceanogr. Rep. 75·18: 16 p. 66
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· Available from : Scientific Info
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FOREWORD On December 13, 1975, the
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ABSTRACT WALTON, A. (ed. ).1978. Me
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5. Organosilicon compounds 6. Cyani
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The consolidated core sample in the
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drive the core barrel through sand
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2.4 Field Notes; Labels for Sample
Page 26: SECTION 4 SAMPLE STORAGE Stored sed
Page 30 and 31: 5.1.4 Dry Coarse Fraction The coars
Page 34: In order to ensure a constant tempe
Page 38 and 39: SECTION 6 CHEMICAL ANALYSIS This se
Page 40 and 41: IV. Reagents Concentrated high puri
Page 42 and 43: (4) The analysis proced ures are ou
Page 44 and 45: (I) Place 220 ml of solution in a 5
Page 46 and 47: Flameless: 0.000 I mgll (solution)
Page 48 and 49: Chelating reagent: ammonium pyrroli
Page 50: B. Reagents Chelating reagent: ammo
Page 54 and 55: efore use. Then rinse with conc. hy
Page 56: (8) Add 3 g of20- 30 mesh high qual
Page 60 and 61: B. Proced ure (\) To 50-ml portion
Page 62 and 63: (5) Analyze the extract or a suitab
Page 64 and 65: will probably involve the analysis
Page 66 and 67: = O.S ml (40°C water bath, use a s
Page 68 and 69: A 9lA-cm column of 10% OV -Ion SO-I
Page 70 and 71: Note: All organohalogen methods sho
Page 72 and 73: (3) Extract benzene extracts from (
Page 74 and 75: VI. Analysis (Coburn et al. 1976) A
Page 78 and 79: SECTION 7 CHEMICAL TESTS WHICH MAY
Page 80: (5) Analyze" after" water sample as
Page 83 and 84: III. Method (Fuller 1969) Place pla
Page 85: GENERAL REFERENCES AND SOURCE MATER
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