This document specifies a method for the quantitative determination of the sum of short-chain polychlorinated n-alkanes also known as short-chain polychlorinated paraffins (SCCPs) in the carbon bond range n-C10 to n-C13 inclusive, in mixtures with chlorine mass fractions ("contents") between 50 % and 67 %, including approximately 6 000 of approximately 8 000 congeners.This method is applicable to the determination of the sum of SCCPs in unfiltered surface water, ground water, drinking water and waste water using gas chromatography-mass spectrometry with electron capture negative ionization (GC-ECNI-MS).Depending on the capability of the GC-ECNI-MS instrument, the concentration range of the method is from 0,1 °g/l or lower to 10 °g/l. Depending on the waste water matrix, the lowest detectable concentration is estimated to be > 0,1 °g/l. The data of the interlaboratory trial concerning this method are given in Annex I.