Determination of tributyltin in marine sediment: Comit� Consultatif pour la Quantit� de Mati�re (CCQM) pilot study P-18 international intercomparison

Abstract

The capabilities of National Metrology Institutes (NMIs -those which are members of the Comité Consultatif pour la Quantité de Matière (CCQM) of the CIPM) and selected outside "expert" laboratories to quantitate (C 4 H 9 ) 3 Sn + (TBT) in a prepared marine sediment were assessed. This exercise was sanctioned by the 7th CCQM meeting, April 4-6, 2001, as an activity of the Inorganic Analysis Working Group and was jointly piloted by the Institute for National Measurement Standards of the National Research Council of Canada (NRC) and the Laboratory of the Government Chemist (LGC), UK. A total of 11 laboratories submitted results (7 NMIs, and 4 external labs). Two external laboratories utilized a standard calibration approach based on a natural abundance TBT standard, whereas all NMIs relied upon isotope dilution mass spectrometry for quantitation. For this purpose, a species specific 117 Sn-enriched TBT standard was supplied by the LGC. No sample preparation methodology was prescribed by the piloting laboratories and, by consequence, a variety of approaches was adopted by the participants, including mechanical shaking, sonication, accelerated solvent extraction, microwave assisted extraction and heating in combination with Grignard derivatization, ethylation and direct sampling. Detection techniques included ICP-MS (with GC and HPLC sample introduction), GC-MS, GC-AED and GC-FPD. Recovery of TBT from a control standard (NRCC CRM PACS-2 marine sediment) averaged 93.5±2.4% (n=14). Results for the pilot material averaged 0.680±0.015 µmol kg -1 (n=14; 80.7±1.8 µg kg -1 ) with a median value of 0.676 µmol kg -1 . Overall, performance was substantially better than state-of-the-art expectations and the satisfactory agreement amongst participants permitted scheduling of a follow-up Key comparison for TBT (K-28), a Pilot intercomparison for DBT (P-43), and certification of the test sediment for TBT content and its release as a new Certified Reference Material (HIPA-1) with a TBT content of 0.679±0.089 µmol kg -1 (expanded uncertainty, k=2, as Sn) (80.5±10.6 µg kg -1 ).

Certification of butyltins and phenyltins in marine sediment certified reference material by species-specific isotope-dilution mass spectrometric analysis using synthesized 118Sn-enriched organotin compounds

“…HIPA-1 and SOPH-1 were certified, and PACS-2 was recertified by NRCC. Their certified and re-certified values were based on results from the Comite Consultatif pour la Quantite de Matiere (CCQM) comparisons [23–25], in which we participated. These CRMs have certified values for DBT and TBT only, and their concentrations are higher than those in CRM7301-a and CRM7306-a.…”

Interpretation of butyltin mass spectra using isotope pattern reconstruction for the accurate measurement of isotope ratios from molecular clusters

“…So far, ID analysis of butyltin species with GC/MS has been performed using various fragment ions from their EI mass spectra. For example, ID analysis of ethylated tributyltin has been performed using clusters C 8 H 19 Sn ( m / z = 235)11, 12, C 10 H 23 Sn ( m / z = 263)11, 13, 14, and C 12 H 27 Sn ( m / z = 291)4, 11, and ethylated dibutyltin has been determined using clusters C 8 H 19 Sn ( m / z = 235)12 and C 10 H 23 Sn ( m / z = 263)4, 13, 14. However, the only justification of such selections seems to be the higher abundance of the ion fragment.…”

“…4) have a large systematic error in order of ∼3%. Despite this fact, it should be noted that this fragment ion has been used in the literature for isotope dilution analysis even in international, interlaboratory comparison studies 11, 12. This clearly demonstrates the need for a quantitative isobar detection algorithm for accurate isotope ratio measurements from molecular clusters.…”

Certification of mono-, di-, and tributyltin compounds in marine sediment certified reference material by species-specific isotope dilution mass spectrometric analysis using synthesized 118 Sn-labeled butyltins

“…Most recently a new CRM, HIPA-1 marine sediment, that has the certified value for TBT has been issued from NRCC/the Laboratory of the Government Chemist, UK (LGC) [10]. The certified values are listed in Table 4.…”