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Figure 5.10 A typical procedure for the extraction of methylmercury .
Table 5.2 Summary of the various methods used for methylmercury determination 
Extraction technique“ Separation technique6 Detection6
250 mg of sample extracted twice with HCl, followed by UV irradiation Ion-exchange (Dowex 1x8 100-200 mesh) AAS
1500-2000 mg of pre-wetted sample extracted with HCl and toluene, followed by LLE with cysteine and back-extraction into toluene“ cGC ECD
800-1000 mg of sample treated with H2SO4, followed by toluene extraction cGC ECD
400-500 mg of sample treated with HCl and extracted into toluene and cysteine, followed by back-extraction into toluene cGC ECD
500 mg of sample treated with NaCl/HCl and extracted into benzene and re-extracted with a thiosulfate solution cGC ECD
50 mg of sample extracted with H2SO4/MeCOOH into water cGC AFS
500 mg of sample treated with NaCl/HCl, extracted into benzene and re-extracted with a thiosulfate solution ETAAS
Table 5.2 (continued )
Methods for Environmental Trace Analysis
Extraction techniquea Separation technique ?b Detection6
100 mg of sample treated with hot HCl and extracted into toluene. Extracts treated with thiosulfate solution and heated. Mercury species converted to hydride with NaBH4 cGC FTIR
50 mg of sample treated with NaCl, followed by HCl, and extracted with DDTC (pH 9) into toluene. Mercury species butylated with Grignard reagent cGC MIP
300 mg of sample distilled with H2SO4 in 20% KCl at 145°C. Mercury species derivatized with 1% NaBEt4 in acetic acid Sediment GC CVAFS
2000 mg of sample treated with HCl, and extracted into toluene and cysteine and back-extracted into toluene cGC ECD
250 mg of sample treated with HCl, followed by toluene extraction cGC ECD
200 mg of sample treated with H2SO4/NaCl and extracted into toluene and thiosulfate solution. Mercury species converted to hydride with NaBH4 cGC CVAAS
250 mg of sample treated with HCl and extracted into toluene, followed by clean-up with cysteine solution, and back-extraction into toluene cGC CVAAS
500 mg of sample microwave-digested with HNO3, followed by derivatization with NaBEt4 cGC QFAAS
200 mg of pre-wetted sample distilled with H2SO4/KCl at 145° C. Mercury species derivatized with NaBEt4 in acetate buffer GC CVAFS
25 mg of sample distilled with H2SO4/NaCl/H2O. Mercury species derivatized with NaBEt4 GC CVAAS
250 mg of sample distilled with H2SO4/NaCl/H2O at 140° C. Distillate treated with 5% NH4OAc at pH 6. Mercury species complexed with 0.5% SPDC HPLC CVAAS
200 mg of sample distilled with H2SO4/NaCl at 145°C. Distillate treated with NH4OAc at pH 6. Mercury species complexed with 0.5 mmoll-1 SPDC, followed by on-line UV irradiation, and reduction by NaBH4 HPLC ICP-MS
1000 mg of sample treated with HCl, extracted into toluene and back-extracted into Na2S2O3. Complexation by mercaptoethanol performed on-line HPLC followed by on-line oxidation (H2SO4 and CuSO4) and reduction with SnCl2 CVAAS
500 mg of sample extracted with supercritical CO2 and eluted with toluene. Mercury species butylated with Grignard reagent cGC MIP
aUV, ultraviolet; LLE, liquid-liquid extraction; DDTC, diethyldithiocarbamate; SPDC, sodium pyrrolidinedithio-carbamate.
bGC, gas chromatography; cGC, capillary gas chromatography; HPLC, high performance liquid chromatography; AAS, atomic absorption spectroscopy; ECD, electron-capture detection; AFS, atomic fluorescence spectroscopy; ETAAS, electrothermal atomization atomic absorption spectroscopy; FTIR, Fourier-transform infrared (spectroscopy); MIP, microwave-induced plasma; CVAFS, cold-vapour atomic fluorescence spectroscopy; QFAAS, quartz-furnace atomic absorption spectroscopy; ICP-MS, inductively coupled plasma-mass spectrometry. cSee Figure 5.10 for a more complete description.
By reference to Table 5.2, can you identify any similarities between the different extraction methods for methylmercury from fish and sediment matrices?
Butyl- and phenyltin compounds are known to be toxic in the marine environment . Historically, tributyltin (TBT) has been released into the marine environment from the leaching of TBT-based antifouling paints used on the undersides of boats and ships. Triphenyltin (TPT) has also been used as an antifouling agent in paint and in herbicide formulations.
Methods have therefore been developed to extract tin compounds from sediment, particularly in estuarine environments. The specific details for organ-otin compound (excluding monoalkyl tin compounds) extraction from sediment, sewage sludge, weeds and fish tissue are shown in Figure 5.11, while the conditions employed for the analysis of organotin extracts by electrothermal (graphite furnace) atomic absorption spectroscopy are shown in Table 5.3. Calibration
Figure 5.11 A typical procedure used for the extraction of organotins .
Methods for Environmental Trace Analysis
Table 5.3 Conditions employed for the analysis of organotin extracts using electrothermal atomic absorption spectroscopy