Tort-2: Lobster hepatopancreas reference material for trace metals

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The following table lists those elements for which certified values have been established. Certified values and their uncertainties are reported as mass fractions (based on dry mass). The uncertainties represent 95% confidence limits for an individual subsample. That is, 95% of samples, 250 mg or greater, from any bottle would be expected to have concentrations within the specified range 95% of the time.

Table 1: Certified quantity values for TORT-2

Element	Mass fraction, (mg/kg)
Arsenic (g,h,m)	21.6 ± 1.8
Cadmium (g,p)	26.7 ± 0.6
Chromium (g,p)	0.77 ± 0.15
Cobalt (g,m)	0.51 ± 0.09
Copper (g,i,p)	106 ± 10
Iron (g,i)	105 ± 13
Lead (g,p)	0.35 ± 0.13
Manganese (g,i,m)	13.6 ± 1.2
Mercury (c,e)	0.27 ± 0.06
Molybdenum (g,p)	0.95 ± 0.10
Nickel (g,p)	2.50 ± 0.19
Selenium (g,h,q)	5.63 ± 0.67
Strontium (i,p)	45.2 ± 1.9
Tin (p)	(0.04)*
Vanadium (g,i,m)	1.64 ± 0.19
Zinc (g,i,p)	180 ± 6
Methylmercury (as Hg)(e,t)	0.152 ± 0.013

* an information value is listed due to insufficient information to accurately assess uncertainties.

Coding

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

• c - cold vapour atomic absorption spectrometry
• e - cold vapour microwave induced plasma atomic emission spectrometry
• g - graphite furnace atomicabsorption spectrometry (GFAAS)
• h - hydride generation GFAAS
• m - inductively coupled plasma mass spectrometry (ICPMS)
• p - isotope dilution inductively coupled
• q - isotope dilution hydride generation ICPMS
• t - gas chromatography - electron capture detection

Intended use

This reference material is primarily intended for use in the calibration of procedures and the development of methods for the determination of trace metals in marine fauna and materials of similar matrix.

Storage and sampling

This material should be stored in a cool and dark location. Prior to use, the bottle should be rotated and shaken to ensure the contents are well mixed. The bottle should be tightly closed thereafter. Certified values are based on a minimum 0.250 g sub-sample from the bottle.

Instructions for drying

Determination of dry mass should be performed on a separate sample to avoid contamination. TORT-2 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.

Preparation of material

The starting material for TORT-2 was freshly frozen "edible grade" lobster tomalley from Prince Edward Island. The processing was performed at the Canadian Institute of Fisheries Technology, Technical University of Nova Scotia, Halifax, Nova Scotia. The material was stored at -30°C to inhibit protein/oil degradation prior to processing. The tomalley was thawed and homogenized to produce a finely divided slurry and spray dried.

Following extraction with acetone to remove the oil, the powder was vacuum dried. The material was then mixed in a rotary blender, screened through a 0.058" polyethylene seive, reblended and bottled. After bottling the material was sterilized by subjecting it to a minimum dose of 25 kGy gamma irradiation at the Canadian Irradiation Centre, Laval, Québec.

Stability

The predecessor CRM, TORT-1 has been periodically analyzed for more than seventeen years and found to be both physically and chemically stable over this time interval. We expect similar results for TORT-2.

The methymercury content of TORT-2 is continually monitored by NRC. Studies indicate the methylmercury content in similar materials has been stable for twelve years. This is not expected to change, provided the material is stored as noted above.

Metrological traceability

Results presented in this certificate are traceable to the SI through gravimetrically prepared standards of established purity and international measurement intercomparisons. As such, they serve as suitable reference materials for laboratory quality assurance programs, as outlined in ISO/IEC 17025. This CRM is registered at the Bureau International des Poids et Mesures (BIPM) in Appendix C of the Comité International des Poids et Mesures database listing Calibration and Measurement Capabilities accepted by signatories to the Mutual Recognition Arrangement of the Metre Convention.

Accreditation

The Chemical Metrology laboratory is compliant to ISO 17025 and ISO Guide 34, with approval by The Inter-American Metrology System (SIM). The certificate of approval is available upon request.

Updates

Users should ensure that the certificate they have is current. The NRC web site will contain any new information.

Acknowledgements

The following staff members of the Measurement Science and Standards portfolio at the NRC contributed to the production and certification of TORT-2: S.S. Berman, V.J. Boyko, V.P. Clancy, J. Lam, P.S. Maxwell, J. W. McLaren, B. Methven, K.W.M. Siu, R.E. Sturgeon and S.N. Willie.

The cooperation of the following in the preparation and analysis of this material is gratefully acknowledged:

C. Hotton, D.S. Singer. I.J. Britt and M.A. Tung, Canadian Institute of Fisheries Technology, Technical University of Nova Scotia, Halifax, Nova Scotia.

D.C. Baxter, H. Emteborg and W. Frech, Department of Chemistry, University of Umeå, S-901 87 Umeå, Sweden.

C. Anderson, M. Deuth and B. Lasorsa, Marine Science Laboratories, Battelle Pacific Northwest, Sequim, Washington.

Date of issue: December 1994
Date of expiry: December 2013

Approved by:

Zoltan Mester, Ph. D.
Group Leader, Chemical Metrology
Measurement Science and Standards

Comments, information and inquiries should be addressed to:

National Research Council of Canada
Measurement Science and Standards
1200 Montreal Road
Building M-12
Ottawa, Ontario K1A 0R6

Telephone: 613-993-2359
Fax: 613-993-2451
Email: CRM-MRCInorganic-Inorganiques@nrc-cnrc.gc.ca