CASS-6: Nearshore Seawater Certified Reference Material for Trace Metals and other Constituents

The following tables show those constituents for which certified, reference and information values have been established for this seawater certified reference material (CRM).

The expanded uncertainty (UCRM) in the certified value is equal to U = kuc where uc is the combined standard uncertainty calculated according to the JCGM Guide [1] and k is the coverage factor. A coverage factor of two (2) was applied for all elements. It is intended that UCRM accounts for every aspect that reasonably contributes to the uncertainty of the measurement. The density of CASS-6 is 1.021 g/mL a 21° C.

Table 1: Certified values for CASS-6

Element Mass fraction,
μg/kg
Mass concentration,
μg/
International recognition of measurement capability (CMC)
boron (a,b) 4010 ± 100 4090 ± 100 -
cadmium (a,b,c) 0.0213 ± 0.0018 0.0217 ± 0.0018 TEW20
cobalt (b,c) 0.0659 ± 0.0052 0.0672 ± 0.0052 TEW22
copper (a,b,c) 0.520 ± 0.032 0.530 ± 0.032 TEW23
iron (a,c) 1.53 ± 0.12 1.56 ± 0.12 TEW24
manganese (b,c) 2.18 ± 0.12 2.22 ± 0.12 TEW26
molybdenum (a,b,c) 8.96 ± 0.52 9.15 ± 0.52 TEW27
nickel (a,b,c) 0.410 ± 0.040 0.418 ± 0.040 TEW28
lead (a,b,c) 0.0104 ± 0.0040 0.0106 ± 0.0040 TEW25
uranium (a,b,c) 2.86 ± 0.42 2.92 ± 0.42 -
zinc (a,b,c) 1.24 ± 0.18 1.27 ± 0.18 TEW30

Table 2: Reference values for CASS-6

Element Mass fraction,
μg/kg
Mass concentration,
μg/
International recognition of measurement capability (CMC)
arsenic (b,c) 1.02 ± 0.10 1.04 ± 0.10 TEW19
chromium (a,b,c) 0.098 ± 0.016 0.100 ± 0.016 TEW21
vanadium (b,c) 0.49 ± 0.12 0.50 ± 0.12 TEW29

Table 3: Information values for CASS-6

Element Mass fraction,
μg/kg
Mass concentration,
μg/L
lanthanum (c) 0.007 0.007
cerium (c) 0.005 0.005
praseodymium (c) 0.002 0.002
neodymium (c) 0.004 0.004
samarium (c) 0.004 0.004
europium (c) 0.002 0.002
gadolinium (c) 0.002 0.002
terbium (c) 0.0003 0.0003
dysprosium 0.0014 0.0014
holmium (c) 0.002 0.002
erbium (c) 0.0014 0.0014
thulium (c) 0.0002 0.0002
ytterbium (c) 0.0016 0.0016
lutetium (c) 0.0004 0.0004

Table 3 (continued): Information values for CASS-6

Compound Mass fraction,
μg/kg
Mass concentration,
μg/L
tributyltin (as Sn) (d,e) 0.000 15 0.000 15
Inorganic arsenic (f) 0.49 0.50
monomethylarsenic (as As) (f) 0.019 0.020
dimethylarsenic (as As) (f) 0.195 0.199
trimethylarsenic (as As) (f) 0.023 0.024

Coding

The coding refers to the instrumental method of analyte determination.

  • a – Isotope dilution inductively-coupled plasma mass spectrometry (ID-ICP-MS)
  • b – Standard addition inductively-coupled plasma mass spectrometry (SA-ICP-MS)
  • c – Inductively-coupled plasma mass spectrometry (ICP-MS)
  • d – Headspace solid phase microextraction (HS-SPME) gas chromatography ID-ICP-MS
  • e – HS-SPME gas chromatography coupled to tandem mass spectrometry
  • f – Hydride generation cryo-trapping ICP-MS

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. A minimum sample volume of 10 mL is recommended.

Uncertainty

Included in the overall combined uncertainty estimate (uc) are uncertainties in the batch characterization (uchar), uncertainties related to possible between-bottle variation (uhom), and uncertainties related to inconsistency between the various measurement methods (umethod). Expressed as standard uncertainties, these components are listed in Table 4.

Table 4: Uncertainty components for CASS-6

Element uc,
μg/kg
uchar,
μg/kg
uhom,
μg/kg
ustability,
μg/kg
boron 50 50 10 0
cadmium 0.0009 0.0008 0.0003 0.0000
cobalt 0.0026 0.0022 0.0014 0.0000
copper 0.016 0.012 0.008 0.008
iron 0.06 0.04 0.05 0.01
manganese 0.06 0.06 0.01 0.00
molybdenum 0.26 0.24 0.09 0.00
nickel 0.020 0.012 0.014 0.008
lead 0.0020 0.0008 0.0018 0.0000
uranium 0.21 0.19 0.01 0.08
zinc 0.09 0.07 0.05 0.00

Table 4 (continued): Uncertainty components for CASS-6

Element uc,
μg/kg
uchar,
μg/kg
uhom,
μg/kg
ustability,
μg/kg
arsenic 0.05 0.05 0.01 0.00
chromium 0.008 0.005 0.006 0.002
vanadium 0.06 0.01 0.02 0.06

Date of issue: February 2016
Date of expiry: December 31, 2018
Revised: January 2017 (inorganic arsenic)

Date modified: