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 ¼g/l or lower to 10 ¼g/l. Depending on the waste water matrix, the lowest detectable concentration is estimated to be > 0,1 ¼g/l.