All stock solutions (1000 ?g g−1 as Sn, Hg or Pb) were prepared by dissolving the corresponding salt either in a 3:1 mixture of acetic acid/methanol for OTC, methanol for MeHg and Et3Pb, 1% HCl in ultrapure water for iHg and were kept in the dark at 4 °C until use. Working
solutions of the organo-tin, -mercury and -lead compounds were prepared daily before analysis by dilution of the stock solutions with 1% HCl in ultrapure water.
2.2.2. Water sample preparation
2.2.3. Sediment sample preparation
2.3. GC-ICP/MS analysis
2.4. Quantification methods
Diethyllead was determined by interpolation on the external calibration curve of Et3Pb as no commercial standard for diethyllead, neither isotopic tracers, Galanthamine
The use of a mixed isotopic spike solution containing 199iHg, 201MeHg, 119MBT, 119DBT, 119TBT, 116MPhT, 116DPhT and 116TPhT allowed to quantify organotin and organomercury compounds by speciated isotope dilution mass spectrometry (SIDMS) which takes into account the cross-species transformations (only for Hg species, in this particular case), the loss of analytes during sample preparation and the signal drift. The isotopic spike was added to sediment
samples after the microwave extraction, as it is well known that no artifacts are formed during this procedural step (Rodriguez Martin-Doimeadios et?al., 2003 and Monperrus et?al., 2003), and method validation through the use of certified reference materials was performed.