230
Phytoplankton
sion to N-hexylaldonamide and alditol acetates. The sample was first hydrolysed with
hydrofluoric acid at 135°C to produce the N-alkylaldonamide acetates.
9.5
Organometallic Compounds
9.5.7
Arsenic
The hydride generation atomic absorption spectrometric method [318], described in
Sect. 4.5.1 for the determination of organoarsenic compounds in marine sediments,
has also been applied to the analysis of algae. The organoarsenic compound was
extracted from the algae by digestion with 0.1 mol 1-1 sodium hydroxide followed by
filtration, concentration to dryness and dissolution of the residue in 8.5 mol I-I
hydrochloric acid. A toluene extract of the acidic phase was prepared, and arsenic
back extracted from this phase with hydrochloric acid-potassium dichromate reagent.
Arsenic species were separated on an ion-exchange column. Arsenic in each of the
fractions was reduced to arsine on a zinc reductor column. Arsine was evaluated in
the extract by carbon tube atomic absorption spectrometry at 193.7 nm
Typical results obtained in a study of the forms of arsenic in several species of
macro algae, tissues of Mercenaria mercenaria, and estuarine sediments collected
from the southern coast of England were discussed.
Inorganic arsenic in algae was in the range 0.1-3.2 mgkg- I , whilst monomethyl
arsenic acid and dimethyl arsinic acids, respectively, were in the ranges 0.2-0.6 and
7.6-15.6 mgkg-I, giving total arsenic contents in the range 20 to 49 mgkg- I .
White and Englar [666] have described a procedure for the determination of
inorganic and organically bound arsenic in marine brown algae. In this method,
inorganic arsenic was removed from the brown algae by distillation as the corresponding trichloride, and assessed by absorption of the arsine-silver diethyldithiocarbamate complex. Severe digestion conditions for organic bound arsenic were found
necessary to determine total arsenic analysed subsequently by the silver diethyldithiocarbamate-pyridine reagent. Arsenic in the inorganic and organic forms ranged from
0.5 to 2.7 and 40.3 to 89.71lg g-I dry weight respectively in seven species of the
Laminariaceae and three species of the Alariaceae and Lessoniaceae collected in
British Columbia, providing levels of inclusion similar to commercially available
brown seaweed products. By contrast, Sargassum muticum contained 20.8 Ilg g-I dry
weight of inorganic arsenic, about 38 % of the total concentration, and a commercial
specimen of Hizikia fusiforme contained 71.8 !lg g-I inorganic arsenic, some 58 % of
the total concentration, suggesting the propensity of members of the Sargassaceae
family to accumulate the inorganic form of arsenic.
Phytoplankton
sion to N-hexylaldonamide and alditol acetates. The sample was first hydrolysed with
hydrofluoric acid at 135°C to produce the N-alkylaldonamide acetates.
9.5
Organometallic Compounds
9.5.7
Arsenic
The hydride generation atomic absorption spectrometric method [318], described in
Sect. 4.5.1 for the determination of organoarsenic compounds in marine sediments,
has also been applied to the analysis of algae. The organoarsenic compound was
extracted from the algae by digestion with 0.1 mol 1-1 sodium hydroxide followed by
filtration, concentration to dryness and dissolution of the residue in 8.5 mol I-I
hydrochloric acid. A toluene extract of the acidic phase was prepared, and arsenic
back extracted from this phase with hydrochloric acid-potassium dichromate reagent.
Arsenic species were separated on an ion-exchange column. Arsenic in each of the
fractions was reduced to arsine on a zinc reductor column. Arsine was evaluated in
the extract by carbon tube atomic absorption spectrometry at 193.7 nm
Typical results obtained in a study of the forms of arsenic in several species of
macro algae, tissues of Mercenaria mercenaria, and estuarine sediments collected
from the southern coast of England were discussed.
Inorganic arsenic in algae was in the range 0.1-3.2 mgkg- I , whilst monomethyl
arsenic acid and dimethyl arsinic acids, respectively, were in the ranges 0.2-0.6 and
7.6-15.6 mgkg-I, giving total arsenic contents in the range 20 to 49 mgkg- I .
White and Englar [666] have described a procedure for the determination of
inorganic and organically bound arsenic in marine brown algae. In this method,
inorganic arsenic was removed from the brown algae by distillation as the corresponding trichloride, and assessed by absorption of the arsine-silver diethyldithiocarbamate complex. Severe digestion conditions for organic bound arsenic were found
necessary to determine total arsenic analysed subsequently by the silver diethyldithiocarbamate-pyridine reagent. Arsenic in the inorganic and organic forms ranged from
0.5 to 2.7 and 40.3 to 89.71lg g-I dry weight respectively in seven species of the
Laminariaceae and three species of the Alariaceae and Lessoniaceae collected in
British Columbia, providing levels of inclusion similar to commercially available
brown seaweed products. By contrast, Sargassum muticum contained 20.8 Ilg g-I dry
weight of inorganic arsenic, about 38 % of the total concentration, and a commercial
specimen of Hizikia fusiforme contained 71.8 !lg g-I inorganic arsenic, some 58 % of
the total concentration, suggesting the propensity of members of the Sargassaceae
family to accumulate the inorganic form of arsenic.