Sediment Certified Reference Materials for the Determination of Tributyltin and Dibutyltin
SOPH-1 was prepared in-house at NRC following gravimetric blending of two NRC CRM marine sediments, PACS-2 and HISS-1, the latter containing negligible concentrations of TBT and thus serving as a solid, inert diluent. HISS-1 was collected from the Hibernia Shelf, off the coast of Newfoundland. PACS-2 was collected in the harbour of Esquimalt, B.C. Both sediments were freeze dried and screened to pass a No. 120 (125 µm) screen and blended by Institute staff using the facilities of CANMET, Mining and Mineral Sciences Laboratories, a division of Natural Resources Canada, in Ottawa.
The particle size distribution was characterized at NRC using a Horiba LA 920 Laser Scattering Distribution Analyser.
Particle Size, µm
Median 12.0
Mean 13.8
Mode 18.6
Storage and Sampling
To ensure the stability of the organotin species it is necessary to store these materials at a temperature of -20oC. Prior to use, the bottle should be well mixed by rotation, shaken and tightly closed immediately thereafter.
Characterisation
Mean values submitted by selected laboratories participating in CCQM P-18, CCQM P-43 and CCQM K-28 were used to calculate the certified value and the
uncertainty of characterization (uchar )[5].
Homogeneity
These materials were tested for homogeneity at NRC. Also, randomly bottles were selected for the analysis by the participating laboratories. Results from different
bottles, as determined by ID-GC-ICP-MS, resulted in an uncertainty as reported in Table 2. The homogeneity is warranted for samples of 500 mg and above.
Stability
Based on a 5 year study of the stability of tributyltin in PACS-2, an uncertainty component was assigned [6]. Similar behaviour from HIPA-1 and SOPH-1 is expected. An uncertainty component associated with the short term stability (transport) was evaluated but considered insignificant. Measurements were conducted on samples stored for one month at -20°C, +4°C and 22°C.
keywords: environmental material , soil/sediment , trace elements , heavy metals , organometallics, speciation analysis, tin speciation |
