Intercomparison 2337: pH, Conductivity, Alkalinity, NO3-N, Cl, SO4, Ca, Mg, Na, K, TOC, Tot-P, Tot-N, Al, Fe, Mn, Cd, Pb, Cu, Ni, and Zn.

Twenty laboratories from fifteen countries accepted the invitation to join the ICP Waters chemical intercomparison. Two sets of samples were prepared and distributed to the participants: one for the determination of ions and one for metals. This year, acceptance rates were based on the Z’-scores obtained by the participants. In general, acceptance rates were high for all parameters. General trends in the choice of techniques continue to shift towards plasma from atomic absorption, and to mass detection from ionic emission. This is especially promising for the determination of metals at low levels.