Metals
93
either in dissolved form or attached to particulate material and thereafter rapidly
taken up by organisms [259-261].
Abo-Rady [262] has described a method for the determination of total inorganic
plus organic mercury in nanogram quantities in sediments. This method is based on
the decomposition of organic and inorganic mercury compounds with acid permanganate, removal of excess permanganate with hydroxylamine hydrochloride, reduction to metallic mercury with tin and hydrochloric acid, and transfer of the liberated
mercury in a stream of air to the spectrometer. Mercury was determined by using a
closed, recirculating air stream. Sensitivity and reproducibility of the 'closed system'
were better, it is claimed, than those of the' open system'. The coefficient of variation
was 5.6 % for sediment samples.
Hutton and Preston [263] have described a non-dispersive atomic fluorescence
method using cold vapour generation for the determination of down to 0.04 mg kg- I
mercury in marine sediments. In this procedure, mercury in the sediment was reduced to its elemental form with acidic stannous chloride solution, and swept with argon
into the fluorimeter. Marine and estuarine sediments examined by this procedure
were found to contain between 1 and 1611g mercury kg-I.
4.2.1
Molybdenum
Pavlova and Yatsimirskii [264] employed a spectrophotometric method based on the
catalytic acceleration by molybdenum of the oxidation of dithiooxamide by hydrogen
peroxide for the determination of down to 2 ng of molybdenum in seawater sediments.
4.2.8
Copper and Nickel
Burzminskii and Fernando [265] studied methods for the extraction of copper and
nickel as their oxalato complexes from deep sea ferromanganese nodules.
4.2.9
Platinum and Iridium
Hodge et al. [266] determined picogram quantltles of these elements in marine
sediments by isolation of anionic forms on a single ion exchange bead followed by
graphite furnace atomic absorption spectrometry.
4.2.70
Scandium
To determine scandium in marine sediments, Shimizu [267] digested the sample with
hydrochloric acid-hydrofluoric acid and then separated scandium from other elements by successive cation and anion exchange chromatography prior to coprecipitation of scandium with ferric hydroxide. Finally, scandium is determined spectrophoto metrically at 610 nm with bromopyrogallol red.
93
either in dissolved form or attached to particulate material and thereafter rapidly
taken up by organisms [259-261].
Abo-Rady [262] has described a method for the determination of total inorganic
plus organic mercury in nanogram quantities in sediments. This method is based on
the decomposition of organic and inorganic mercury compounds with acid permanganate, removal of excess permanganate with hydroxylamine hydrochloride, reduction to metallic mercury with tin and hydrochloric acid, and transfer of the liberated
mercury in a stream of air to the spectrometer. Mercury was determined by using a
closed, recirculating air stream. Sensitivity and reproducibility of the 'closed system'
were better, it is claimed, than those of the' open system'. The coefficient of variation
was 5.6 % for sediment samples.
Hutton and Preston [263] have described a non-dispersive atomic fluorescence
method using cold vapour generation for the determination of down to 0.04 mg kg- I
mercury in marine sediments. In this procedure, mercury in the sediment was reduced to its elemental form with acidic stannous chloride solution, and swept with argon
into the fluorimeter. Marine and estuarine sediments examined by this procedure
were found to contain between 1 and 1611g mercury kg-I.
4.2.1
Molybdenum
Pavlova and Yatsimirskii [264] employed a spectrophotometric method based on the
catalytic acceleration by molybdenum of the oxidation of dithiooxamide by hydrogen
peroxide for the determination of down to 2 ng of molybdenum in seawater sediments.
4.2.8
Copper and Nickel
Burzminskii and Fernando [265] studied methods for the extraction of copper and
nickel as their oxalato complexes from deep sea ferromanganese nodules.
4.2.9
Platinum and Iridium
Hodge et al. [266] determined picogram quantltles of these elements in marine
sediments by isolation of anionic forms on a single ion exchange bead followed by
graphite furnace atomic absorption spectrometry.
4.2.70
Scandium
To determine scandium in marine sediments, Shimizu [267] digested the sample with
hydrochloric acid-hydrofluoric acid and then separated scandium from other elements by successive cation and anion exchange chromatography prior to coprecipitation of scandium with ferric hydroxide. Finally, scandium is determined spectrophoto metrically at 610 nm with bromopyrogallol red.