MOOS-3: Seawater certified reference material for nutrients

The following table lists the measurements 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. It is intended that UCRM encompasses every aspect that reasonably contributes to the uncertainty in amount content.

Table 1: Certified Quantity Values

Nutrient Form Concentration,
µmol/L
Mass concentration,
mg/L
Mass fraction,
mg/kg
Phosphate (a,b) P 1.60 ± 0.15 0.050 ± 0.005 0.048 ± 0.004
PO43– 1.60 ± 0.15 0.152 ± 0.014 0.147 ± 0.013
Silicate (a,c,d) Si 30.5 ± 0.8 0.86 ± 0.02 0.83 ± 0.02
SiO2 30.5 ± 0.8 1.83 ± 0.05 1.78 ± 0.04
Nitrite (e) N 3.54 ± 0.06 0.0496 ± 0.0008 0.0481 ± 0.0008
NO2 3.54 ± 0.06 0.1630 ± 0.0026 0.1581 ± 0.0026
Nitrate (e) N 23.0 ± 0.3 0.322 ± 0.005 0.313 ± 0.004
NO3 23.0 ± 0.3 1.427 ± 0.020 1.384 ± 0.020
Nitrite plus nitrate (f) N 26.6 ± 0.3 0.372 ± 0.005 0.361 ± 0.004

Additional information:

Density of MOOS‑3 (at 20 oC) as determined by pycnometry:
ρMOOS‑3 = 1.0307(8) kg/L;

Mass concentration of nitrite as determined by colorimetry:
γ(NO2) = 0.157(15) mg/L or γ(N) = 0.048(5) mg/L.

Standard atomic weights used:
Ar(N) = 14.0069(2), Ar(O) = 15.9994(2),
Ar(P) = 30.973 762(2), Ar(Si) = 28.0850(6)

Coding

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

  • a - Spectrophotometry
  • b - Ion exchange chromatography inductively coupled plasma mass spectrometry (ICPMS)
  • c - Isotope dilution ICPMS
  • d - Inductively coupled plasma atomic emission spectrometry
  • e - Isotope dilution gas chromatography mass spectrometry
  • f - Calculated from nitrite and nitrate content

Intended Use

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

Uncertainty

Included in the overall combined uncertainty estimate (uc) are uncertainties in the batch characterization (uchar) and uncertainties related to possible between-bottle variation (uhom). Expressed as standard uncertainties relative to the combined uncertainty, these components are listed below:

Table 2: Relative uncertainty components

Nutrient uc,
relative
uchar,
relative
uhom,
relative
Phosphate (PO43–) 100% 66% 34%
Silicate (SiO32–) 100% 94% 6%
Nitrite (NO2) 100% 96% 4%
Nitrate (NO3) 100% 93% 7%

Date of issue: November 2013
Date of expiry: November 2018
Revised: November 2014, March 2016 (editorial update), May 2016 (editorial update, storage and sampling section update)

Date modified: