HIPA-1: Sediment for the Determination of Tributyltin

Sediment Certified Reference Materials for the Determination of Tributyltin


HIPA-1 is a sediment reference material that 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.

HIPA-1 Particle Size, µm
Median      14.5
Mean         18.1
Mode         19.6


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.