SQID-1: Cuttlefish certified reference material for trace metals, arsenobetaine, and methylmercury

The following tables show those trace elements along with arsenic and mercury species for which certified, reference and information values have been established for this cuttlefish 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. All listed values are expressed on a dry mass basis.

Table 1: Certified values for SQID‑1

Element/compound Mass Fraction,
mg/kg
arsenic (b,c) 14.1 ± 2.2
cadmium (a,c) 0.0691 ± 0.0106
mercury (a,c) 0.342 ± 0.054
lead (a,c) 0.1433 ± 0.0098
arsenobetaine (as As) (e,f) 13.96 ± 0.54

Table 2: Reference values for SQID‑1

Element/compound Mass Fraction,
mg/kg
calcium (c) 760 ± 100
copper (c,d) 5.7 ± 0.8
magnesium (c) 1750 ± 180
phosphorus (c,d) 8400 ± 400
potassium (c) 4660 ± 1420
sodium (c) 14 600 ± 1600
strontium (c) 7.2 ± 1.2
uranium (c) 0.0062 ± 0.0018
zinc (c,d) 63 ± 8
methylmercury (as Hg) (g) 0.324 ± 0.028

Table 3: Information values for SQID‑1

Element/compound Mass Fraction,
mg/kg
antimony (c) 0.12
chromium (c) 1.7
cobalt (c) 0.016
iron (c,d) 8.5
manganese (c) 1.9
molybdenum (c) 0.052
selenium (c) 2.03
silver (c) 0.040
tin (c) 0.037
dimethylarsenic (as As) (e) 0.03
arsenic(III) (inorganic) (e) 0.019
arsenic(V) (inorganic) (e) 0.028

Coding

The coding refers only 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 (ICP-MS)
  • c - Inductively-coupled plasma mass spectrometry (ICP-MS)
  • d - Inductively-coupled plasma atomic emission spectroscopy (ICP-AES)
  • e - Standard addition liquid chromatography ICP-MS (LC-ICP-MS)
  • f - Isotope dilution liquid chromatography electrospray orbitrap mass spectrometry
  • g - Isotope dilution gas chromatography ICP-MS (ID-GC-ICP-MS)

Intended use

This reference material is primarily intended for use for the development of methods for the determination of matrix trace metals and metal speciation in marine fauna and materials with similar matrices. A minimum sample mass of 250 mg is recommended.

Storage and sampling

It is recommended that the material be stored at –20oC. Each bottle is packaged in a trilaminate aluminium foil pouch which serves as an impermeable vapour barrier. The bottle contents should be well mixed by rotation and shaking prior to use, and tightly closed immediately thereafter. Certified values are based on a minimum 250 mg sub-sample from the bottle.

Instructions for drying

Although initially free from moisture following the freeze drying, the materials adsorb moisture during subsequent operations. A separate sample aliquot should be dried to a constant mass to obtain moisture content. SQID‑1 can be dried to constant mass by: (1) drying at reduced pressure (e.g., 50 mm Hg) at room temperature in a vacuum desiccator over magnesium perchlorate for 24 hours; (2) vacuum drying (about 0.5 mm Hg) at room temperature for 24 hours. The moisture content is estimated at 0.011 g/g.

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 SQID‑1

Element/compound uc,
mg/kg
uchar,
mg/kg
uhom,
mg/kg
umethod,
mg/kg
arsenic 1.1 0.3 0.2 1.0
cadmium 0.0053 0.0022 0.0031 0.0037
mercury 0.027 0.011 0.004 0.024
lead 0.0049 0.0025 0.0042 0.0000
arsenobetaine (as As) 0.27 0.22 0.15 0.00
calcium 50 20 0 50
copper 0.4 0.3 0.0 0.3
magnesium 90 90 0 0
phosphorus 200 200 0 0
potassium 710 710 0 0
sodium 800 800 0 0
strontium 0.6 0.5 0.0 0.3
uranium 0.0009 0.0009 0.0000 0.0000
zinc 4 4 0 0
methylmercury (as Hg) 0.014 0.014 0.000 0.000

Date of issue: July 2016
Date of expiry: July 2023
Revised: May 2018 (date of expiry extended)

Date modified: