Metals
175
interference from copper, iron, and nickel cations. With the described procedure, the
arsenic found in NBS 1566 standard oyster tissue (13.17 ± 0.34 mg kg-I) agreed well
with the certified value of 13.4 ± 1.9 mg kg-I. Sensitivity and absolute detection limits
of the method were 0.11 ng and 0.14 ng respectively.
Gas Chromatography. Siu et al. [540] determined arsenic in standard reference materials including lobster hepatopancreas and oyster tissue. Biological samples were
analysed after digestion with concentrated acid and derivatization with 2,3dimercaptopropanol using gas chromatography with electron capture detection. Results of analysis compared favourably with certified values. A detection limit of 10 pg
was reported with an analytical precision of 10 %.
Brzezinska-Paudyn et al. [541] compared detection limits for arsenic in various
standard references samples (oyster, lobster, scallop) for five different analytical
techniques. The results obtained by graphite furnace atomic absorption, combined
furnace-flame atomic absorption, nondestructive neutron activation analysis, conventional inductively coupled plasma atomic emission spectroscopy (ICP AES), and
flow injection /hydride generation ICPAES showed all these methods were appropriate for arsenic determinations at concentrations higher than 5 mg kg-I. Graphite furnace atomic absorption, with a L'vov platform and nickel matrix modifier, was the most
suitable method for analysis of arsenic in biological materials. This method had a
detection limit of 0.5-1.0 mg kg-I.
8.1.2
Cadmium
Atomic Absorption Spectrometry. This technique has been applied to the determination of cadmium in mussels [542, 543] and clam tissue [360].
The molybdenum and lanthanum coated graphite furnace atomic absorption spectrometric method [360], described in Sect. 7.1.2 for the determination of cadmium in
fish, has also been applied to the determination of cadmium in clam tissue. An
average value of 1.3 mg kg-I was found. The determined cadmium content (0.31 ±
0.05 mg kg-I) of NBS SRM 1577 bovine liver standard is in good agreement with the
nominal value (0.34 ± 0.04 mg kg-I). Average analytical recovery of cadmium in the
clam sample is 104 ± 10 %.
Cadmium determinations in clam tissue digests obtained by the above procedure
agreed well with those obtained by anodic scanning voltammetry in the range 1.0 to
2.3 mgkg-I.
Ashworth and Farthing [543] have described a procedure for extracting cadmium
from common mussels prior to analysis by atomic absorption spectrometry. The
individual whole mussels were dehydrated to constant weight at 50 °c, digested under
simple reflux in nitric acid, and the solution buffered to pH 5 with sodium hydroxide
and sodium citrate. The cadmium was extracted into dithizone in methyl isobutyl
ketone and the organic layer stored in polyethylene containers for analysis by atomic
absorption spectrometry.
Mussels collected from the same region of Port Phillip Bay were found to have a
cadmium concentration of approximately 0.5 mg kg-I dry weight. A surprisingly high
175
interference from copper, iron, and nickel cations. With the described procedure, the
arsenic found in NBS 1566 standard oyster tissue (13.17 ± 0.34 mg kg-I) agreed well
with the certified value of 13.4 ± 1.9 mg kg-I. Sensitivity and absolute detection limits
of the method were 0.11 ng and 0.14 ng respectively.
Gas Chromatography. Siu et al. [540] determined arsenic in standard reference materials including lobster hepatopancreas and oyster tissue. Biological samples were
analysed after digestion with concentrated acid and derivatization with 2,3dimercaptopropanol using gas chromatography with electron capture detection. Results of analysis compared favourably with certified values. A detection limit of 10 pg
was reported with an analytical precision of 10 %.
Brzezinska-Paudyn et al. [541] compared detection limits for arsenic in various
standard references samples (oyster, lobster, scallop) for five different analytical
techniques. The results obtained by graphite furnace atomic absorption, combined
furnace-flame atomic absorption, nondestructive neutron activation analysis, conventional inductively coupled plasma atomic emission spectroscopy (ICP AES), and
flow injection /hydride generation ICPAES showed all these methods were appropriate for arsenic determinations at concentrations higher than 5 mg kg-I. Graphite furnace atomic absorption, with a L'vov platform and nickel matrix modifier, was the most
suitable method for analysis of arsenic in biological materials. This method had a
detection limit of 0.5-1.0 mg kg-I.
8.1.2
Cadmium
Atomic Absorption Spectrometry. This technique has been applied to the determination of cadmium in mussels [542, 543] and clam tissue [360].
The molybdenum and lanthanum coated graphite furnace atomic absorption spectrometric method [360], described in Sect. 7.1.2 for the determination of cadmium in
fish, has also been applied to the determination of cadmium in clam tissue. An
average value of 1.3 mg kg-I was found. The determined cadmium content (0.31 ±
0.05 mg kg-I) of NBS SRM 1577 bovine liver standard is in good agreement with the
nominal value (0.34 ± 0.04 mg kg-I). Average analytical recovery of cadmium in the
clam sample is 104 ± 10 %.
Cadmium determinations in clam tissue digests obtained by the above procedure
agreed well with those obtained by anodic scanning voltammetry in the range 1.0 to
2.3 mgkg-I.
Ashworth and Farthing [543] have described a procedure for extracting cadmium
from common mussels prior to analysis by atomic absorption spectrometry. The
individual whole mussels were dehydrated to constant weight at 50 °c, digested under
simple reflux in nitric acid, and the solution buffered to pH 5 with sodium hydroxide
and sodium citrate. The cadmium was extracted into dithizone in methyl isobutyl
ketone and the organic layer stored in polyethylene containers for analysis by atomic
absorption spectrometry.
Mussels collected from the same region of Port Phillip Bay were found to have a
cadmium concentration of approximately 0.5 mg kg-I dry weight. A surprisingly high