Organometallic Compounds
65
Hg kg-I, i. e. relative standard deviations ofS.4-12 % at the 17.2-32.3 mg Hg kg-I level
in sediments. Recoveries in methyl mercuric chloride spiking studies were between S5
and 125 %.
Cappon and Crispin Smith [ISO] have described a method for the extraction,
clean-up and gas chromatographic determination of alkyl and aryl mercury compounds in sediments. The organomercury compounds are converted to their chloroderivatives and solvent extracted. Inorganic mercury is then isolated as methylmercury upon reaction with tetramethyltin. The initial extract is subjected to a thiosulphate
clean-up and the organomercury species are isolated as their bromoderivatives. Total
mercury recovery was in the range 75-90 % and down to 1 ~g kg- I of specific compounds can be determined.
Cold vapour atomic absorption spectrometry has been applied to the determination of methylmercury compounds in sediments [lSI, lS2]
2.5.3
Tin
Various workers have discussed the determination of alkyl and aryltin compounds in
sediments [lS3-1S6]. In the method described by Hattori et al. [lS3], the sediment
samples were extracted into methanolic hydrochloric acid and then, following mixing
with water and sodium chloride, the mixture was extracted with benzene. Following
dehydration and concentration, the tin compounds were cleaned up on a silica gel
column impregnated with hydrochloric acid and then hydrides generated using an
ethanol solution of sodium borohydride. The organotin hydrides were determined
using gas chromatography with electron-capture detection. Recoveries were 70-95 %
from sediment samples and the detection limits 0.02 mg kg-I.
Mueller [lS4] described a method for determining 0.5 ~g kg- I tributyltin in sediments in which tributyltin is first converted to tributyl methyltin and then analysed
using capillary gas chromatography with flame photometric detection and gas chromatography-mass spectrometry.
Gilmour et al. [ISS] determined picogram quantities ofmethyltins in sediments as
their hydride derivatives (methylstannanes) using gas chromatographyquadrupole
mass spectrometry. Hydride derivatives were prepared by addition of sodium borohydride in a closed, flow-through system. Borate buffer was added to the samples and
hydrogen generated from the borohydride which resulted in high purge efficiencies
for mono-di- and tri-methyltin. Selected ion monitoring with the mass spectrometer
allowed detection limits of 3-5 pg as tin for methyltins. Detection limits for 5 g
sediment sample were below pg tin g-I levels with a standard deviation of 6-1S %
depending on the methyltin species and the sample type.
Rapsomankis et al. [lS6] studied the biological methylation of inorganic tin in river
sediments Cal et al. [739] employed derivativization and supercritical fluid extraction
for the simultaneous determination of butyltin and phenyltin compounds from sediments.
65
Hg kg-I, i. e. relative standard deviations ofS.4-12 % at the 17.2-32.3 mg Hg kg-I level
in sediments. Recoveries in methyl mercuric chloride spiking studies were between S5
and 125 %.
Cappon and Crispin Smith [ISO] have described a method for the extraction,
clean-up and gas chromatographic determination of alkyl and aryl mercury compounds in sediments. The organomercury compounds are converted to their chloroderivatives and solvent extracted. Inorganic mercury is then isolated as methylmercury upon reaction with tetramethyltin. The initial extract is subjected to a thiosulphate
clean-up and the organomercury species are isolated as their bromoderivatives. Total
mercury recovery was in the range 75-90 % and down to 1 ~g kg- I of specific compounds can be determined.
Cold vapour atomic absorption spectrometry has been applied to the determination of methylmercury compounds in sediments [lSI, lS2]
2.5.3
Tin
Various workers have discussed the determination of alkyl and aryltin compounds in
sediments [lS3-1S6]. In the method described by Hattori et al. [lS3], the sediment
samples were extracted into methanolic hydrochloric acid and then, following mixing
with water and sodium chloride, the mixture was extracted with benzene. Following
dehydration and concentration, the tin compounds were cleaned up on a silica gel
column impregnated with hydrochloric acid and then hydrides generated using an
ethanol solution of sodium borohydride. The organotin hydrides were determined
using gas chromatography with electron-capture detection. Recoveries were 70-95 %
from sediment samples and the detection limits 0.02 mg kg-I.
Mueller [lS4] described a method for determining 0.5 ~g kg- I tributyltin in sediments in which tributyltin is first converted to tributyl methyltin and then analysed
using capillary gas chromatography with flame photometric detection and gas chromatography-mass spectrometry.
Gilmour et al. [ISS] determined picogram quantities ofmethyltins in sediments as
their hydride derivatives (methylstannanes) using gas chromatographyquadrupole
mass spectrometry. Hydride derivatives were prepared by addition of sodium borohydride in a closed, flow-through system. Borate buffer was added to the samples and
hydrogen generated from the borohydride which resulted in high purge efficiencies
for mono-di- and tri-methyltin. Selected ion monitoring with the mass spectrometer
allowed detection limits of 3-5 pg as tin for methyltins. Detection limits for 5 g
sediment sample were below pg tin g-I levels with a standard deviation of 6-1S %
depending on the methyltin species and the sample type.
Rapsomankis et al. [lS6] studied the biological methylation of inorganic tin in river
sediments Cal et al. [739] employed derivativization and supercritical fluid extraction
for the simultaneous determination of butyltin and phenyltin compounds from sediments.