Annex I
177
Annex I
Determination of metals in water
Learning objective:
To illustrate an analytical process used in the determination of a wide variety of metals in different types of water. Depending on the particular concentration level, a direct process or one
that includes preconcentration by liquid-liquid extraction of the corresponding metal chelates is used.
Reference:
Standard Methods for Examination of Water and Wastewater
American Public Health Association, Washington, D.C., 1989, pp 152-157.
303 A. Determination of Antimony, Bismuth, Cadmium, Calcium, Cesium, Chromium, Cobalt, Copper, Gold,
Iridium, Iron, Lead, Lithium, Magnesium, Nickel, Platinum, Potassium, Rhodium, Ruthenium, Silver, Sodium,
Strontium, Thallium, Tin and Zinc by Direct Aspiration into an Air- Acetylene Flame
1. Apparatus
Atomic absorption spectrophotometer and
associated equipment: See Sect. 303.2. Use
burner head recommended by the manufacturer.
2. Reagents
a. Air, cleaned and dried through a suitable
filter to remove oil, water and other foreign
substances. The source may be a compressor
or commercially bottled gas.
b. Acetylene, standard commercial grade.
Acetone, which always is present in acetylene
cylinders, can be prevented from entering
and damaging the burner head by replacing a
cylinder when its pressure has fallen to 689
kPa acetylene.
c. Metal-free water: Use metal-free water
to prepare all reagents and calibration standards, and also as dilution water. Prepare
metal-free water by de-ionizing tap water
andlor by using one of the following processes, depending on the metal concentration in
the sample: single distillation, redistillation
or sub-boiling. Always check de-ionized or
distilled water to determine whether the element of interest is present in trace amounts.
(CAUTION: If the source water contains Hg
or other volatile metals, de-ionized and
single- or redistilled water may not be suitable for trace analysis because these metals
distill over with the distilled water. In such
cases, use sub-boiling to prepare metal-free
water).
d. Calcium solution: Dissolve 630 mg calciumcarbonate,CaC03,in 50 mL ofl + 5 HC!.
If necessary, heat and boil gently to obtain
complete solution. Cool and dilute to 1000
mL with water.
e. Hydrochloric acid. HCI, cone.
f. Lanthanum solution: Dissolve 58.65 g
lanthanum oxide, La203, in 250 mL cone. HC!.
Add acid slowly until the material is dissolved and dilute to 1000 mL with water.
g. Hydrogen peroxide. 30%.
h. Nitric acid. HN03, cone.
i. Aqua regia: Add 3 volumes cone. HCI to
1 volume cone HN03.
j. Iodine solution, 1 N: Dissolve 20 g potassium iodide, KI, in 50 mL water, add 12.7 g
iodine and dilute to 100 mL.
k. Cyanogen iodide (CNI) solution: To 50
mL water add 6.5 g potassium cyanide, KCN,
5.0 mL 1 N iodine solution, and 4.0 mL cone.
NH40H. Mix and dilute to 100 mL with water.
Prepare fresh solution every 2 weeks.
!. Standard metal solutions: Prepare a
series of standard metal solutions in the
optimum concentration range by appropriate dilution of the following stock metal
solutions with water containing 1.5 mL cone
HN03/L. Thoroughly dry reagents before
use. In general, use reagents of the highest
purity. For hydrates, use fresh reagents.
177
Annex I
Determination of metals in water
Learning objective:
To illustrate an analytical process used in the determination of a wide variety of metals in different types of water. Depending on the particular concentration level, a direct process or one
that includes preconcentration by liquid-liquid extraction of the corresponding metal chelates is used.
Reference:
Standard Methods for Examination of Water and Wastewater
American Public Health Association, Washington, D.C., 1989, pp 152-157.
303 A. Determination of Antimony, Bismuth, Cadmium, Calcium, Cesium, Chromium, Cobalt, Copper, Gold,
Iridium, Iron, Lead, Lithium, Magnesium, Nickel, Platinum, Potassium, Rhodium, Ruthenium, Silver, Sodium,
Strontium, Thallium, Tin and Zinc by Direct Aspiration into an Air- Acetylene Flame
1. Apparatus
Atomic absorption spectrophotometer and
associated equipment: See Sect. 303.2. Use
burner head recommended by the manufacturer.
2. Reagents
a. Air, cleaned and dried through a suitable
filter to remove oil, water and other foreign
substances. The source may be a compressor
or commercially bottled gas.
b. Acetylene, standard commercial grade.
Acetone, which always is present in acetylene
cylinders, can be prevented from entering
and damaging the burner head by replacing a
cylinder when its pressure has fallen to 689
kPa acetylene.
c. Metal-free water: Use metal-free water
to prepare all reagents and calibration standards, and also as dilution water. Prepare
metal-free water by de-ionizing tap water
andlor by using one of the following processes, depending on the metal concentration in
the sample: single distillation, redistillation
or sub-boiling. Always check de-ionized or
distilled water to determine whether the element of interest is present in trace amounts.
(CAUTION: If the source water contains Hg
or other volatile metals, de-ionized and
single- or redistilled water may not be suitable for trace analysis because these metals
distill over with the distilled water. In such
cases, use sub-boiling to prepare metal-free
water).
d. Calcium solution: Dissolve 630 mg calciumcarbonate,CaC03,in 50 mL ofl + 5 HC!.
If necessary, heat and boil gently to obtain
complete solution. Cool and dilute to 1000
mL with water.
e. Hydrochloric acid. HCI, cone.
f. Lanthanum solution: Dissolve 58.65 g
lanthanum oxide, La203, in 250 mL cone. HC!.
Add acid slowly until the material is dissolved and dilute to 1000 mL with water.
g. Hydrogen peroxide. 30%.
h. Nitric acid. HN03, cone.
i. Aqua regia: Add 3 volumes cone. HCI to
1 volume cone HN03.
j. Iodine solution, 1 N: Dissolve 20 g potassium iodide, KI, in 50 mL water, add 12.7 g
iodine and dilute to 100 mL.
k. Cyanogen iodide (CNI) solution: To 50
mL water add 6.5 g potassium cyanide, KCN,
5.0 mL 1 N iodine solution, and 4.0 mL cone.
NH40H. Mix and dilute to 100 mL with water.
Prepare fresh solution every 2 weeks.
!. Standard metal solutions: Prepare a
series of standard metal solutions in the
optimum concentration range by appropriate dilution of the following stock metal
solutions with water containing 1.5 mL cone
HN03/L. Thoroughly dry reagents before
use. In general, use reagents of the highest
purity. For hydrates, use fresh reagents.