『Abstract
　The NTA/EDTA fractionation of sediment-bound, inorganic phosphate was improved and made more effective. The iron-bound phosphate is now extracted with Ca-EDTA plus dithionite and followed by an extraction of calcium-bound phosphate by Na2-EDTA at pH = 4.5. A comparison is made with two other sequential extraction procedures: the SEDEX and the Hieltjes & Lijklema extractions. The EDTA extractions have an advantage over the other two methods.』

Abbreviations

　ASOP = Acid Soluble Organic Phosphate
　CaCO3−P = calcium-bound phosphate
　EDTA = Ethylene dinitrilo tetraacetic acid (or its salts)
　Fe(OOH)−P = iron-bound phosphate
　M = mol dm^-3
　NaOH-Pextr = phosphate extracted with NaOH (etc.)
　NTA = Nitrilo triacetic acid (or its salts)
　o-P = ortho phosphate
　TRIS-buffer = tris (hydroximethyl)-amino methane

Introduction
Methods
Results
Discussion
Comparison between old and new NTA/EDTA methods
Comparison of different methods
Acknowledgments
References
Annex 1
Protocol
Annex 2