NASS-6: Seawater reference material for trace metals

The following table lists the elements for which certified values have been established, along with their expanded uncertainty(UCRM) = kuc, where uc is the combined standard uncertainty calculated according to the JCGM Guide and k=2 is the coverage factor.” According to the english certificate should read as “along with their expanded uncertainty (UCRM= kuc, where uc is the combined standard uncertainty calculated according to the JCGM Guide and k=2 is the coverage factor). The difference being how the parentheses are used. It is intended that UCRM encompasses every aspect that reasonably contributes to the uncertainty of the certified mass fraction. Certified values are based on the results of determinations by at least two independent methods of analysis. Information values (identified with an "*") are listed for elements which could not be certified because of insufficient information for accurate assessment of the associated uncertainties. A measured density of 1.024 g/mL was used to calculate mass concentrations in NASS-6.

Table 1: Certified quantity value

Element Mass Fraction,
μg/kg
Mass Concentration,
μg/L
Arsenic (j,r) 1.40 ± 0.12 1.43 ± 0.12
Cadmium (i,p,r,t) 0.0303 ± 0.0019 0.0311 ± 0.0019
Chromium (p,r) 0.116 ± 0.008 0.118 ± 0.008
Cobalt (q) 0.015* 0.015*
Copper (i,p,r) 0.242 ± 0.025 0.248 ± 0.025
Iron (i,p) 0.483 ± 0.045 0.495 ± 0.046
Lead (p,t) 0.006 ± 0.002 0.006 ± 0.002
Manganese (i,q) 0.516 ± 0.047 0.530 ± 0.050
Molybdenum (p) 9.66 ± 0.70 9.89 ± 0.72
Nickel (i, p, r) 0.294 ± 0.025 0.301 ± 0.025
Uranium (p) 3.* 3.*
Vanadium (q,t) 1.42 ± 0.16 1.46 ± 0.17
Zinc (i,p) 0.251 ± 0.020 0.257 ± 0.020

Coding

The coding refers only to the instrumental method of analyte determination.

  • i - Immobilized ligand separation, determination by graphite furnace atomic absorption spectrometry (GFAAS)
  • j - Hydride generation, atomic absorption determination
  • p - Immobilized ligand separation, determination by isotope dilution ICPMS
  • q - Immobilized ligand separation, determination by ICPMS
  • r - Reductive precipitation separation, determination by GFAAS
  • r - Reductive precipitation separation, determination by GFAAS
  • t - Immobilized ligand separation, determination by ICP-TOFMS

Intended use

This certified reference material is primarily intended for use in the calibration of procedures and the development of methods used for the analysis of seawater for trace metals.

Date of issue: June 2010
Date of expiry: June 2020
Revised: February 2012 (Mo updated), March 2016 (editorial update)

Date modified: