| Several analytical approaches for the determination of butyltin (BT) species in sediments have been developed. An initial method, based on HPLC separation, utilized a strong cation-exchange column and an ammonium citrate buffer in a 60:40 methanol-water mixture as mobile phase in combination with ICP-MS detection. Separation of monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT) could be achieved in 8 minutes with estimated detection limits [3 times the standard deviation (SD) of sample blanks] of 0.08, 0.05 and 0.03 mug g-1 for MBT, DBT and TBT, respectively, normalized to a 0.5 g sub-sample. This approach was used to investigate microwave assisted extraction procedures for determination of BT in PACS-2 sediment certified reference material (CRM), as well as an initial stability study of butyltins in this sediment.; A GC-ICP-MS method was subsequently developed with which chromatographic separation of MBT, DBT and TBT could be achieved in 10 minutes with method detection limits of 0.006, 0.001 and 0.002 mug g-1 for MBT, DBT and TBT, respectively, based on a 0.5 g sub-sample. In addition to the slightly better precisions obtained in measured BT concentrations, resolution and sensitivity achieved for all BT peaks by GC-ICP-MS were far better than could be obtained using HPLC-ICP-MS. The GC-ICP-MS method was used to study the effects of gamma-sterilization on homogeneity of BTs and their content in candidate sediment CRMs, as well as their stability in PACS-2 sediment.; Since the accuracy of the natural abundance BT standards is critical for obtaining reliable results, a unique approach, using hydride generation (HG) GC-MS, was developed to quantify any inorganic Sn, MBT, DBT and TBT impurities in these BT calibration solutions. The true natural abundance BT concentrations were obtained following correction for these impurities.; To achieve accurate and precise results, isotope dilution (ID) calibration was applied to the determination of BTs in PACS-2. Significant improvements (close to 4-fold) in precision of measurement of TBT using a 117Sn-enriched TBT spike were obtained with both HPLC- and GC-ICP-MS methods, clearly demonstrating the superiority of ID as compared to the method of standard additions. A performance comparison was also made between a sector field and quadrupole ICP-MS instrument used for these measurements.; In an effort to simplify sample preparation for GC separation, solid phase microextraction (SPME) was investigated for determination of TBT in PACS-2. To overcome poor precision (typically 10% RSD) associated with SPME, species specific ID was investigated. (Abstract shortened by UMI.)... |
