“…Cool, and determine absorbance at 820 µ in a colorimeter or spectrophotometer, using water to set the instrument. Discussion Gedansky et al (12) clearly demonstrated the necessity for an oxidizing and fusing medium in the combustion zone to achieve high recoveries of phosphorus by the combustion technique. The use of anhydrous sodium carbonate as recommended by these workers proved inconvenient for the techniques used in this study; therefore, an alternative medium was developed in which the combustion paper was dipped into an aqueous alcoholic sodium hydroxide solution prior to application of the sam- pie.…”