Rapid perchloric acid digestion methods for analysis of phosphorus and sulfur in aquacultural wastewater and biosolids by ion chromatography

Abstract

Ion chromatography (IC) is one of the most efficient analytical techniques available for the determination of ions in solution. However, there is a need for an equally efficient organic matter destruction procedure which does not lengthen run times due to matrix effects. Rainbow trout manure (RTM) was digested with 1.0 mL each of nitric acid (HNO₃) and perchloric acid (HClO₄) and subsequently cleared with 1.0 mL hydrogen peroxide (H₂O₂) for a total digestion time of 30 min. Rainbow trout effluent (RTE) was lyophilized and then digested with 50 μL of HClO₄ and 100 μL H₂O₂ for 15 min. Phosphate (PO₄) and sulfate (SO₄) were separated and quantified with a Dionex IonPac‐AG4A guard column in less than 10 min. Digestion of RTM gave complete recovery of phosphorus (P) and sulfur (S); digestion of RTE gave complete recovery of P and 86% recovery of S. By combining the rapid IC method with the HClO₄ digestion procedure developed in this paper, ion chromatography can rapidly quantitate P and S in rainbow trout effluent and manure.