Wet oxidation with dichromate

The following method has been designed to give a rapid estimation of the amount of particulate organic material in sea water. The method involves the wet oxidation of carbon by acid dichromate and is based on the procedure described by Johnson (/. Biol. Chem., 181 707, 1949) adapted by us to spectrophotometry. The method may give higher results than the classic determination of carbon by measurement of carbon dioxide but the simplicity of the procedure allows a large number of determinations to be performed even under shipboard conditions without the use of specialized or complex equipment. 

The particulate matter is filtered on to a glass-fiber filter. Carbon is then determined by wet ashing with a mixture of potassium dichromate and concentrated sulphuric acid, and measuring the decrease in extinction of the yellow dichromate solution after it has been reduced by the organic matter. 

50-ml stoppered graduated measuring cylinders. There may be a requirement for 100-ml stoppered graduated cylinders. 

30-ml Pyrex glass beakers fitted with coverglasses. 

For details concerning the cleaning of this and other glassware, see Section F. 

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