Metals
7
Table 2.1
Native arsenic and arsenic recovered from river sediment samples (from [3])
Arsenic 1lS/15 g
Native
Added
Total
Recovered Recovery Standard
Deviation
%
%
Sediment (North Edisto River) 1.02
2.0
3.05
2.03
101.5
4.9
Sediment (South Edisto River) 1.27
2.0
3.18
1.91
95.5
4.2
Sediment (Caw Caw Swamp)
3.16
2.0
5.13
1.97
98.5
4.3
Goulden et al. [4] have described a continuous flow semi-automated system for the
determination of arsenic (and selenium, see later) in river sediments. By use of a
four-fold preconcentration step, detection limits of 0.02 Ilg I-I were achieved for
arsenic. Sediments were brought into solution by fusion with sodium hydroxide in a
zirconium crucible. Arsenic is determined using inductively coupled argon plasma
excitation (ICAP) using a plasma power of 1400 W. The manifold used for the sodium
borohydride automated hydride generation is shown in Fig. 2.1a whilst Fig.2.1b
shows details of the gas separation employed.
Sediment samples are pretreated in the following way. Into a zirconium crucible,
2 g of solid sodium hydroxide is placed and 0.2 g of the dried ground sediment is
added. The crucible is placed in a cold furnace which is then heated to 350°C for 2 h.
The crucible is cooled and the contents are dissolved in 40 ml of 0.2 N hydrochloric
acid. Then 20 ml hydrochloric acid is added and the solution heated to about 90°C for
I h. The precipitated silicic acid is allowed to settle and the solution decanted into the
sampler tubes. A calibration curve is obtained by using standard solutions of arsenic
in 4 N hydrochloric acid. The results obtained by this method in arsenic determinations on reference soils are shown below.
Sample
Nominal
Found
So-1
1.9
1.9
So-2
1.2
1.3
So-3
2.6
2.6
So-4
7.1
6.5
IAEA soils a
93.9 ± 7.5
95.1
NBS (SRMI645)
66.0
66.4
International Atomic Energy Authority, Vienna, Brannon and Patrick [19] have reported on the transformation and fixation of arsenic(V) in anaerobic sediments and
long term release of natural and added arsenic, and sediment properties which
affected the mobilization of arsenic(III), arsenic(V) and organic arsenic.
2.1.3
Bismuth
Bismuth has been determined in amounts down to 1 mg kg- I in river sediments by
electrothermal atomic absorption spectrometry with low temperature atomization
7
Table 2.1
Native arsenic and arsenic recovered from river sediment samples (from [3])
Arsenic 1lS/15 g
Native
Added
Total
Recovered Recovery Standard
Deviation
%
%
Sediment (North Edisto River) 1.02
2.0
3.05
2.03
101.5
4.9
Sediment (South Edisto River) 1.27
2.0
3.18
1.91
95.5
4.2
Sediment (Caw Caw Swamp)
3.16
2.0
5.13
1.97
98.5
4.3
Goulden et al. [4] have described a continuous flow semi-automated system for the
determination of arsenic (and selenium, see later) in river sediments. By use of a
four-fold preconcentration step, detection limits of 0.02 Ilg I-I were achieved for
arsenic. Sediments were brought into solution by fusion with sodium hydroxide in a
zirconium crucible. Arsenic is determined using inductively coupled argon plasma
excitation (ICAP) using a plasma power of 1400 W. The manifold used for the sodium
borohydride automated hydride generation is shown in Fig. 2.1a whilst Fig.2.1b
shows details of the gas separation employed.
Sediment samples are pretreated in the following way. Into a zirconium crucible,
2 g of solid sodium hydroxide is placed and 0.2 g of the dried ground sediment is
added. The crucible is placed in a cold furnace which is then heated to 350°C for 2 h.
The crucible is cooled and the contents are dissolved in 40 ml of 0.2 N hydrochloric
acid. Then 20 ml hydrochloric acid is added and the solution heated to about 90°C for
I h. The precipitated silicic acid is allowed to settle and the solution decanted into the
sampler tubes. A calibration curve is obtained by using standard solutions of arsenic
in 4 N hydrochloric acid. The results obtained by this method in arsenic determinations on reference soils are shown below.
Sample
Nominal
Found
So-1
1.9
1.9
So-2
1.2
1.3
So-3
2.6
2.6
So-4
7.1
6.5
IAEA soils a
93.9 ± 7.5
95.1
NBS (SRMI645)
66.0
66.4
International Atomic Energy Authority, Vienna, Brannon and Patrick [19] have reported on the transformation and fixation of arsenic(V) in anaerobic sediments and
long term release of natural and added arsenic, and sediment properties which
affected the mobilization of arsenic(III), arsenic(V) and organic arsenic.
2.1.3
Bismuth
Bismuth has been determined in amounts down to 1 mg kg- I in river sediments by
electrothermal atomic absorption spectrometry with low temperature atomization