3500 OTHER METALS

The following sections contain background information on, and refer the user to analytical methods for, a diverse group of metals that

occur in nature and/or have important industrial uses.

3500-Sb Antimony

Antimony (Sb) is the fourth element in Group VA in the

periodic table; it has an atomic number of 51, an atomic weight

of 121.75, and valences of 3 and 5. The average abundance of Sb

in the earth’s crust is 0.2 ppm; in soils it is 1 ppm; in streams it

is 1 g/L, and in groundwaters it is 0.1 mg/L. Antimony is

sometimes found native, but more commonly in stibnite (Sb2S3).

It is used in alloys of lead and in batteries, bullets, solder,

pyrotechnics, and semiconductors.

The common aqueous species are SbO2

, HSbO2, and complexes with carbonate and sulfate. Soluble salts of antimony are

toxic. The U.S. EPA primary drinking water standard MCL is 6

g/L.

The electrothermal atomic absorption spectrometric method

(3113B) or the inductively coupled plasma/mass spectrometric

method (3125) are the methods of choice because of their sensitivity. Alternatively use the flame atomic absorption spectrometric method (3111B) or the inductively coupled plasma

method (3120) when high sensitivity is not required.

3500-Ba Barium

Barium (Ba) is the fifth element in Group IIA in the

periodic table; it has an atomic number of 56, an atomic

weight of 137.33, and a valence of 2. The average abundance

of Ba in the earth’s crust is 390 ppm; in soils it is 63 to 810

ppm; in streams it is 10 mg/L; in U.S. drinking waters it is 49

g/L; and in groundwaters it is 0.05 to 1 mg/L. It is found

chiefly in barite (BaSO4) or in witherite (BaCO3). Barium’s

main use is in mud slurries used in drilling oil and exploration

wells, but it is also used in pigments, rat poisons, pyrotechnics, and in medicine.

The solubility of barium in natural waters is controlled by the

solubility of BaSO4, and somewhat by its adsorption on hydroxides. High concentrations of barium occur in some brines. Concentrations exceeding 1 mg/L constitute a toxicity hazard in the

marine environment. The U.S. EPA primary drinking water

standard MCL is 1 mg/L.

Perform analyses by the atomic absorption spectrometric

methods (3111D or E), the electrothermal atomic absorption

method (3113B), or the inductively coupled plasma methods

(3120 or 3125).

3500-Be Beryllium

Beryllium (Be) is the first element in Group IIA of the periodic

table; it has an atomic number of 4, an atomic weight of 9.01,

and a valence of 2. The average abundance of Be in the earth’s

crust is 2 ppm; in soils it is 0.8 to 1.3 ppm; in streams it is 0.2

g/L, in U.S. drinking waters and in groundwaters it is typically

0.1 g/L. Beryllium occurs in nature in deposits of beryls in

granitic rocks. Beryllium is used in high-strength alloys of copper and nickel, windows in X-ray tubes, and as a moderator in

nuclear reactors.

Beryllium solubility is controlled in natural waters by the

solubility of beryllium hydroxides. The solubility at pH 6.0 is

approximately 0.1 g/L. It is nonessential for plants and animals.

Acute toxicity occurs at 130 g/L, and chronic toxicity at 5 g/L

in freshwater species. The United Nations Food and Agriculture

Organization recommended maximum level for irrigation waters

is 100 g/L. The U.S. EPA primary drinking water standard

MCL for beryllium is 4 g/L.

The atomic absorption spectrometric methods (3111D and E,

and 3113B) and the inductively coupled plasma (ICP) methods

(3120 and 3125) are the methods of choice. If atomic absorption

or ICP instrumentation is not available, the aluminon colorimetric method detailed in the 19th Edition of Standard Methods may

be used. This method has poorer precision and bias than the

methods of choice.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

1
3500-Bi Bismuth

Bismuth (Bi) is the fifth element in Group VA in the periodic

table; it has an atomic number of 83, an atomic weight of 208.98,

and valences of 3 and 5. The average abundance of Bi in the

earth’s crust in 0.08 ppm; in streams it is 0.02 mg/L, and in

groundwaters it is 0.1 mg/L. Bismuth occurs in association

with lead and silver ores, and occasionally as the native element.

210Bi, 212Bi, and 214Bi are naturally occuring radioisotopes produced in the decay of uranium and thorium. The metal is used in

alloys of lead, tin, and cadmium, and in some pharmaceuticals.

In natural water, Bi3 ion will occur, and complex ions with

nitrate and chloride also might be expected. The iodide and

telluride compounds are toxic by ingestion or inhalation.

Perform analyses by the atomic absorption spectrometric

method (3111B) or by the electrothermal atomic absorption

method (3113B). The inductively coupled plasma mass spectrometric method (3125) also may be applied successfully in most

cases (with lower detection levels), even though bismuth is not

specifically listed as an analyte in the method.

3500-B Boron

See Section 4500-B.

3500-Cd Cadmium

Cadmium (Cd) is the second element in Group IIB of the

periodic table; it has an atomic number of 48, an atomic weight

of 112.41, and a valence of 2. The average abundance of Cd in

the earth’s crust is 0.16 ppm; in soils it is 0.1 to 0.5 ppm; in

streams it is 1 g/L, and in groundwaters it is from 1 to 10 g/L.

Cadmium occurs in sulfide minerals that also contain zinc, lead,

or copper. The metal is used in electroplating, batteries, paint

pigments, and in alloys with various other metals. Cadmium is

usually associated with zinc at a ratio of about 1 part cadmium

to 500 parts zinc in most rocks and soils.

The solubility of cadmium is controlled in natural waters by

carbonate equilibria. Guidelines for maximum cadmium concentrations in natural water are linked to the hardness or alkalinity

of the water (i.e., the softer the water, the lower the permitted

level of cadmium). It is nonessential for plants and animals.

Cadmium is extremely toxic and accumulates in the kidneys

andliver, with prolonged intake at low levels sometimes leading

to dysfunction of the kidneys. The United Nations Food and

Agriculture Organization recommended maximum level for cadmium in irrigation waters is 10 g/L. The U.S. EPA primary

drinking water standard MCL is 10 g/L.

The electrothermal atomic absorption spectrometric method

(3113B) is preferred. The flame atomic absorption methods

(3111B and C) and inductively coupled plasma methods (3120

and 3125) provide acceptable precision and bias, with higher

detection limits. Anodic stripping voltammetry (3130B) can

achieve superior detection limits, but is susceptible to interferences from copper, silver, gold, and organic compounds. When

atomic absorption spectrometric or inductively coupled plasma

apparatus is unavailable and the desired precision is not as great,

the dithizone method detailed in the 19th Edition of Standard

Methods is suitable.

3500-Cs Cesium

Cesium (Cs) is the sixth element in Group IA of the

periodic table; it has an atomic number of 55, an atomic

weight of 132.90, and a valence of 1. The average abundance

of Cs in the earth’s crust is 2.6 ppm; in soils it is 1 to 5 ppm;

in streams it is 0.02 mg/L; and in groundwaters it is generally

0.1 mg/L. Cesium is found in lepidolite and in the water of

certain mineral springs. 137Cs, with a 33-year half-life, is

widely dispersed on the earth’s surface as a result of the

radioactive fallout from the atmospheric testing of nuclear

weapons. Cesium compounds are used in photoelectric cells,

as a catalyst, and in brewing. Some cesium compounds are

fire hazards.

Perform analyses by the flame atomic absorption spectrometric method (3111B). The inductively coupled plasma/mass spectrometric method (3125) also may be applied successfully in

most cases (with lower detection levels), even though cesium is

not specifically listed as an analyte in the method.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

3500 OTHER METALS/Cesium

2
3500-Co Cobalt

Cobalt (Co) is the second element in Group VIII in the

periodic table; it has an atomic number of 27, an atomic weight

of 58.93, and valences of 1, 2, and 3. The average abundance of

Co in the earth’s crust is 29 ppm; in soils it is 1.0 to 14 ppm; in

streams it is 0.2 g/L; and in groundwaters it is 1 to 10 g/L.

Cobalt occurs only sparingly in ores, usually as the sulfide or the

arsenide. It is widely used in alloys of various steels, in electroplating, in fertilizers, and in porcelain and glass.

The solubility of cobalt is controlled by coprecipitation or

adsorption by oxides or manganese and iron, by carbonate precipitation, and by the formation of complex ions. Cobalt dust is

flammable and is toxic by inhalation. Cobalt is considered essential for algae and some bacteria, nonessential for higher

plants, and an essential trace element for animals. The United

Nations Food and Agriculture Organization recommended maximum level for irrigation waters is 100 g/L.

Perform analyses by the flame atomic absorption spectrometric methods (3111B and C), by the electrothermal atomic absorption method (3113B), or by the inductively coupled plasma

methods (3120 and 3125).

3500-Ga Gallium

Gallium (Ga) is the third element in Group IIIA in the periodic

table; it has an atomic number of 31, an atomic weight of 67.72,

and valences of 1, 2, and 3. The average abundance of Ga in the

earth’s crust is 19 ppm; in soils it is 1.9 to 29 ppm; in streams it

is 0.09 g/L; and in groundwaters it is 0.1 mg/L. Gallium

occurs in many zinc ores, and nearly always in bauxite. Gallium

compounds are used in semiconducting devices.

The element exists as Ga3 in natural water, and its solubility

is controlled by formation of the hydroxide. It is considered

nonessential for plants and animals.

Perform analyses by the electrothermal atomic absorption

method (3113B). The inductively coupled plasma/mass spectrometric method (3125) also may be applied successfully in most

cases (with lower detection levels), even though gallium is not

specifically listed as an analyte in the method.

3500-Ge Germanium

Germanium (Ge) is the third element in Group IVA in the

periodic table; it has an atomic number of 32, an atomic weight

of 72.59, and valences of 2 and 4. The average abundance of Ge

in the earth’s crust is 1.5 ppm; in streams it is 0.03 to 0.1 g/L;

and in groundwaters it is 0.1 mg/L. Germanium is found in

germanite, in certain zinc ores, and in elevated levels in certain

hot spring waters. Germanium alloys are used in transistors, gold

alloys, phosphors, and semiconducting devices.

Germanium is present in natural waters in the tetravalent state,

and its distribution in natural waters probably is controlled by

adsorption on clay mineral surfaces. It is nonessential for plants

and animals.

Perform analyses by the electrothermal atomic absorption

method (3113B). The inductively coupled plasma/mass spectrometric method (3125) also may be applied successfully in most

cases (with lower detection levels), even though germanium is

not specifically listed as an analyte in the method.

3500-Au Gold

Gold (Au) is the third element in Group IB in the periodic

table; it has an atomic number of 79, an atomic weight of 196.97,

and valences of 1 and 3. The average abundance of Au in the

earth’s crust is 0.004 ppm; in streams it is 2 g/L; and in

groundwater it is 0.1 mg/L. Gold occurs in the native form, and

is associated with quartz or pyrite. The main uses of gold are in

jewelry, dentistry, electronics, and the aerospace industry.

Gold solubility is restricted to acidic waters in the presence of

oxidizing agents and chloride, or in alkaline solutions in the

presence of hydrogen sulfide. Its solubility may be influenced by

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

3500 OTHER METALS/Gold

3
natural organic acids. Compounds of gold containing thiosulfate

and cyanide have some human toxicity.

Perform analyses by the atomic absorption spectrometric

method (3111B) or by the electrothermal atomic absorption

method (3113B). The inductively coupled plasma mass spectrometric method (3125) also may be applied successfully in

most cases (with lower detection levels), even though gold is

not specifically listed as an analyte in the method.

3500-In Indium

Indium (In) is the fourth element in Group IIIA in the periodic

table; it has an atomic number of 49, an atomic weight of 114.82,

and valences of 1, 2, and 3. The average abundance of indium in

the earth’s crust is 0.19 ppm; in streams it is 0.01 g/L; and in

groundwaters it is 0.1 mg/L. Indium often occurs in combination with zinc ores, and sometimes with pyrites and siderite.

Indium is used in alloys for bearings, brazing, solder, and in

electrical devices.

Indium exists as In3 and as a number of complex ions. Its

solubility is controlled by the formation of the insoluble hydroxide. The metal and its compounds are toxic by inhalation.

Perform analyses by the electrothermal atomic absorption

method (3113B). The inductively coupled plasma mass spectrometric method (3125) also may be applied successfully in most

cases (with lower detection levels), even though indium is not

specifically listed as an analyte in the method.

3500-Ir Iridium

Iridium (Ir) is the eighth element in Group VIII of the periodic

table; it has an atomic number of 77, an atomic weight of 192.2,

and valences of 1, 3, and 4. The average abundance of Ir in the

earth’s crust is probably 0.001 ppm, and in groundwaters it is

0.1 mg/L. Iridium occurs uncombined with platinum and other

metals. It is used in alloys with platinum in catalysts, thermocouples, electrodes, and wires.

The aqueous chemistry is controlled by complex compounds,

although the solubility in natural waters is relatively unknown.

Perform analyses by the flame atomic absorption spectrometric method (3111B). The inductively coupled plasma/mass spectrometric method (3125) also may be applied successfully in

most cases (with lower detection levels), even though iridium is

not specifically listed as an analyte in the method.

3500-Hg Mercury

Mercury (Hg) is the third element in Group IIB in the periodic

table; it has an atomic number of 80, an atomic weight of 200.59,

and valences of 1 and 2. The average abundance of Hg in the

earth’s crust is 0.09 ppm; in soils it is 30 to 160 ppb; in streams

it is 0.07 g/L, and in groundwaters it is 0.5 to 1 g/L. Mercury

occurs free in nature, but the chief source is cinnabar (HgS).

Mercury is used in amalgams, mirror coatings, vapor lamps,

paints, measuring devices (thermometers, barometers, manometers), pharmaceuticals, pesticides, and fungicides. It is often used

in paper mills as a mold retardant for paper.

The common aqueous species are Hg2, Hg(OH)2

0

, Hg0, and

stable complexes with organic ligands. Inorganic mercury can be

methylated in sediments when sulfides are present to form dimethyl mercury, (CH3)2Hg, which is very toxic and can concentrate in the aquatic food chain. Mercury poisoning occurred in

Japan in the 1950s as the result of consumption of shellfish that

had accumulated mercury. In times past, mercury was used in the

haberdashery industry to block hats (the cause of the “mad

hatter” syndrome).

Mercury is considered nonessential for plants and animals.

The U.S. EPA primary drinking water standard MCL is 2 g/L.

The cold-vapor atomic absorption method (3112B) is the

method of choice for all samples. The inductively coupled

plasma mass spectrometric method (3125) also may be applied

successfully in some cases, even though mercury is not specifically listed as an analyte in the method. The dithizone method

detailed in the 19th edition of Standard Methods can be used for

determining high levels of mercury (2 g/L) in potable waters.

Because mercury can be lost readily from samples, preserve

them by treating with HNO3 to reduce the pH to 2 (see Section

1060). Glass storage containers are preferred to plastic, because

they can extend the holding time to 30 d, rather than only the

14 d allowed in plastic containers.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

3500 OTHER METALS/Mercury

4
3500-Mo Molybdenum

Molybdenum (Mo) is the second element in Group VIB in the

periodic table; it has an atomic number of 42, and atomic weight of

95.95, and valences of 2, 3, 4, 5, and 6. The average abundance of

Mo in the earth’s crust is 1.2 ppm; in soils it is 2.5 ppm; in streams

it is 1 g/L, and in groundwaters it is 0.1 mg/L. Molybdenum

occurs naturally as molybdenite (MoS2) and wulfenite (PbMoO4). It

is used in alloys, ink pigments, catalysts, and lubricants.

The common aqueous species are HMoO4

, MoO42, and

organic complexes. It is considered an essential trace element for

plants and animals. The United Nations Food and Agriculture

Organization recommended maximum level for irrigation waters

is 0.01 mg/L.

Use one of the flame atomic absorption spectrometric methods

(3111D or E), the electrothermal atomic absorption spectrometric method (3113B), or one of the inductively coupled plasma

methods (3120 or 3125).

3500-Ni Nickel

Nickel (Ni) is the third element in Group VIII in the periodic

table; it has an atomic number of 28, an atomic weight of 58.69,

and a common valence of 2 and less commonly 1, 3, or 4. The

average abundance of Ni in the earth’s crust is 1.2 ppm; in soils

it is 2.5 ppm; in streams it is 1 g/L, and in groundwaters it is

0.1 mg/L. Nickel is obtained chiefly from pyrrhotite and garnierite. Nickel is used in alloys, magnets, protective coatings,

catalysts, and batteries.

The common aqueous species is Ni2. In reducing conditions

insoluble sulfides can form, while in aerobic conditions nickel

complexes with hydroxide, carbonates, and organic ligands can

form. It is suspected to be an essential trace element for some

plants and animals. The United Nations Food and Agriculture

Organization recommended maximum level for irrigation waters

is 200 g/L. The U.S. EPA primary drinking water standard

MCL is 0.1 mg/L.

The atomic absorption spectrometric methods (3111B and C),

the inductively coupled plasma methods (3120 and 3125), and

the electrothermal atomic absorption spectrometric method

(3113B) are the methods of choice for all samples.

3500-Os Osmium

Osmium (Os) is the seventh element in Group VIII in the

periodic table; it has an atomic number of 76, an atomic weight

of 190.2, and valences of 3, 4, and 6, and less commonly 1, 2, 5,

7, and 8. The average abundance of Os in the earth’s crust is

probably 0.005 ppm, and in groundwaters it is 0.01 mg/L.

Osmium occurs in iridosime and in platinum-bearing river sands.

Osmium is used as a hardener with iridium and as a catalyst with

platinum.

The aqueous chemistry is controlled by complex compounds, although the solubility in natural waters is relatively

unknown.

Analyze by flame atomic absorption methods (3111D and E).

3500-Pd Palladium

Palladium (Pd) is the sixth element in Group VIII of the periodic

table; it has an atomic number of 46, an atomic weight of 106.42,

and valences of 2 and 4. Palladium occurs with platinum in nature.

It is used in alloys to make electrical relays, catalysts, in the making

f “white gold,” and in protective coatings.

Palladium has no known toxic effects. The United Nations

Food and Agriculture Organization recommended maximum

level for irrigation waters is 5 mg/L.

Preferably analyze by flame atomic absorption method

(3111B). The inductively coupled plasma mass spectrometric

method (3125) also may be applied successfully in most cases

(with lower detection levels), even though palladium is not

specifically listed as an analyte in the method.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

3500 OTHER METALS/Palladium

5
3500-Pt Platinum

Platinum (Pt) is the ninth element in Group VIII of the

periodic table; it has an atomic number of 78, an atomic

weight of 195.1, and valences of 2 and 4. The average

abundance of Pt in the earth’s crust is probably 0.01 ppm,

and in groundwaters it is 0.1 mg/L. Platinum is usually

found in its native state, but also may be found as sperrylite

(PtAs2). Platinum is used as a catalyst and in laboratory ware,

jewelry, and surgical wire.

The aqueous chemistry in natural waters is relatively unknown, although its solubility is probably controlled by complex

compounds. In powder form, platinum can be flammable, and its

soluble salts are toxic by inhalation.

Preferably analyze by flame atomic absorption method

(3111B). The inductively coupled plasma mass spectrometric

method (3125) also may be applied successfully in most cases

(with lower detection levels), even though platinum is not specifically listed as an analyte in the method.

3500-Re Rhenium

Rhenium (Re) is the third element in Group VIIB in the

periodic table; it has an atomic number of 75, an atomic weight

of 186.21, and valences of 1 through 7, with 7 being the most

stable. The average abundance of Re in the earth’s crust is 7

ppm, and in groundwaters it is 0.1 mg/L. Rhenium is found in

columbite, tantalite, and wolframite, as well as in molybdenum

ore concentrates. It is used in tungsten-molybdenum-based alloys, thermocouples, filaments, and flash bulbs. Rhenium in the

powder form can be flammable.

For analysis methods, see flame atomic absorption methods

(3111D and E). The inductively coupled plasma mass spectrometric method (3125) also may be applied successfully in most

cases (with lower detection levels), even though rhenium is not

specifically listed as an analyte in the method.

3500-Rh Rhodium

Rhodium (Rh) is the fifth element in Group VIII in the periodic

table; it has an atomic number of 45, an atomic weight of 102.91,

and valences of 1 through 6, the most common being 1 and 3.

Rhodium is found in its native state in platinum-bearing sands. It is

used in platinum alloys for thermocouples, electrical contacts, and

jewelry.

The aqueous chemistry in natural waters is relatively unknown. The metal is flammable in the powder form, and its salts

are toxic by inhalation.

For analysis see flame atomic absorption method (3111B). The

inductively coupled plasma/mass spectrometric method (3125)

also may be applied successfully in most cases (with lower

detection levels), even though rhodium is not specifically listed

as an analyte in the method.

3500-Ru Ruthenium

Ruthenium (Ru) is the fourth element in Group VIII in the

periodic table; it has an atomic number of 44, an atomic weight

of 101.07, and valences of 1 through 7, the most common being

2, 3, and 4. The average abundance of Ru in the earth’s crust is

probably 0.01 ppm, and in groundwaters it is 0.1 mg/L. It

occurs in its native state in platinum-bearing river sands. It is

used in jewelry with platinum, in electrical contacts, and as a

catalyst.

The aqueous chemistry in natural waters is relatively unknown. Ruthenium has no known toxic effects.

For analysis see flame atomic absorption method (3111B). The

inductively coupled plasma mass spectrometric method (3125)

also may be applied successfully in most cases (with lower

detection levels), even though ruthenium is not specifically listed

as an analyte in the method.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

3500 OTHER METALS/Ruthenium

6
3500-Ag Silver

Silver (Ag) is the second element in Group IB of the periodic

table; it has an atomic number of 47, an atomic weight of 107.87,

and valences of 1 and 2. The average abundance of Ag in the

earth’s crust is 0.08 ppm; in soils it is 0.01 to 0.5 ppm; in

streams it is 0.3 g/L; in U.S. drinking waters it is 0.23 g/L,

and in groundwater it is 0.1 g/L. Silver occurs in its native

state and in combination with many nonmetallic elements such

as argentite (Ag2S) and horn silver (AgCl). Lead and copper ores

also may yield considerable silver. Silver is widely used in

photography, silverware, jewelry, mirrors, and batteries. Silver

iodide has been used in the seeding of clouds, and silver oxide to

a limited extent is used as a disinfectant for water.

In acidic water Ag would predominate, and in highchloride water a series of complexes would be expected.

Silver is nonessential for plants and animals. Silver can cause

argyria, a permanent, blue-gray discoloration of the skin and

eyes that imparts a ghostly appearance. Concentrations in the

range of 0.4 to 1 mg/L have caused pathological changes in

the kidneys, liver, and spleen of rats. Toxic effects on fish in

fresh water have been observed at concentrations as low as

0.17 g/L. For freshwater aquatic life, total recoverable silver

should not exceed 1.2 mg/L.

The atomic absorption spectrometric methods (3111B and C)

and the inductively coupled plasma methods (3120 and 3125) are

preferred. The electrothermal atomization method (3113B) is the

most sensitive for determining silver in natural waters. The

dithizone method detailed in the 19th edition of Standard Methods can be used when an atomic absorption spectrometer is

unavailable. A method suitable for analysis of silver in industrial

or other wastewaters at levels above 1 mg/L is available.1

If total silver is to be determined, acidify sample with conc nitric

acid (HNO3) to pH 2 at time of collection. If sample contains

particulate matter and only the “dissolved” metal content is to be

determined, filter through a 0.45-m membrane filter at time of

collection. After filtration, acidify filtrate with HNO3 to pH 2.

Complete analysis as soon after collection as possible. Some samples may require special storage and digestion; see Section 3030D.

Reference

1. U.S. ENVIRONMENTAL PROTECTION AGENCY. 1994. Approved Inorganic

Test Procedures. Federal Register 59(20):4504.

3500-Te Tellurium

Tellurium (Te) is the fourth element in Group VIA in the periodic

table; it has an atomic number of 52, an atomic weight of 127.60,

and valences of 2, 4, and 6. The average abundance of Te in the

earth’s crust is 0.002 ppm; in soils it is 0.001 to 0.01 ppm; and in

groundwaters it is 0.1 mg/L. Tellurium is found in its native state

and as the telluride of gold and other metals. It is used in alloys,

catalysts, batteries, and as a coloring agent in glass and ceramics.

The common aqueous species is TeO3

2. The metal and its

compounds are toxic by inhalation.

Perform analyses by the electrothermal atomic absorption

method (3113B). The inductively coupled plasma mass spectrometric method (3125) also may be applied successfully in most

cases (with lower detection limits), even though tellurium is not

specifically listed as an analyte in the method.

3500-Tl Thallium

Thallium (Tl) is the fifth element in Group IIIA in the

periodic table; it has an atomic number of 81, an atomic

weight of 204.38, and valences of 1 and 3. The average

abundance in the earth’s crust is 0.07 ppm, and in groundwaters it is 0.1 mg/L. The metal occurs chiefly in pyrites.

Thallium is used in the production of glasses and rodenticides, in photoelectric applications, and in electrodes for

dissolved oxygen meters.

The common aqueous species is Tl. It is nonessential for

plants and animals. Compounds of thallium are toxic on contact

with moisture, and by inhalation. The U.S. EPA primary drinking water standard MCL is 2 g/L.

For analysis, use one of the atomic absorption spectrometric methods

(3111B or 3113B), or one of the inductively coupled plasma methods

(3120 or 3125), depending upon sensitivity requirements.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

3500 OTHER METALS/Thallium

7
3500-Th Thorium

Thorium (Th) is the first element in the actinium series of the

periodic table; it has an atomic number of 90, an atomic weight

of 232.04, and a valence of 4. The average abundance in the

earth’s crust is 8.1 ppm; in soils it is 13 ppm; in streams it is 0.1

g/L, and in groundwaters it is 0.1 mg/L. Thorium is a

radioactive element, with 232Th having a half-life of 1.4  1010

years. It is widely distributed in the earth, with the principal

mineral being monazite. Thorium is used in sun lamps, photoelectric cells, incandescent lighting, and gas mantles.

The aqueous chemistry of thorium is controlled by the Th4

ion, which forms a set of complex species with hydroxides.

Thorium’s radioactive decay isotopes are dangerous when inhaled or ingested as thorium dust particles.

Either of the flame atomic absorption spectrometric methods

(3111D or E) may be used for analysis. The inductively coupled

plasma mass spectrometric method (3125) also may be applied

successfully in most cases (with lower detection limits), even

though thorium is not specifically listed as an analyte in the method.

3500-Sn Tin

Tin (Sn) is the fourth element in Group IVA in the periodic

table; it has an atomic number of 50, an atomic weight of 118.69,

and valences of 2 and 4. The average abundance in the earth’s

crust is 2.1 ppm; in soils it is 10 ppm; in streams it is 0.1 g/L,

and in groundwaters it is 0.1 mg/L. Tin is found mostly in the

mineral cassiterite (SnO2), in association with granitic rocks. Tin

is used in reducing agents, solder, bronze, pewter, and coatings

for various metals.

The common aqueous species are Sn4, Sn(OH)4,

SnO(OH)2, and SnO(OH)3

. Tin is adsorbed to suspended

solids, sulfides, and hydroxides. Tin can be methylated in

sediments. Tributyl tin undergoes biodegradation quickly.

Organo-tin compounds are toxic. Tin is considered nonessential for plants and animals.

Either the flame atomic absorption method (3111B) or the

electrothermal atomic absorption method (3113B) may be used

successfully for analyses, depending upon the sensitivity desired.

The inductively coupled plasma/mass spectrometric method

(3125) also may be applied successfully in most cases (with

lower detection limits), even though tin is not specifically listed

as an analyte in the method.

3500-Ti Titanium

Titanium (Ti) is the first element in Group IVB in the periodic

table; it has an atomic number of 22, an atomic weight of 47.88, and

valences of 2, 3, and 4. The average abundance of Ti in the earth’s

crust is 0.6%; in soils it is 1700 to 6600 ppm; in streams it is 3 g/L,

and in groundwaters it is 0.1 mg/L. The element is commonly

associated with iron minerals. Titanium is used in alloys for aircraft,

marine, and food-handling equipment. Compounds of the metal are

used in pigments and as a reducing agent.

Titanium species are usually insoluble in natural waters, with the

Ti4 species being the most common ion when found. Some compounds are toxic by ingestion and the pure metal is flammable.

Either of the flame atomic absorption spectrometric methods

(3111D or E) may be used. The inductively coupled plasma mass

spectrometric method (3125) also may be applied successfully in

most cases (with lower detection limits), even though titanium is

not specifically listed as an analyte in the method.

3500-U Uranium

Uranium (U) is the third element in the actinide series of the

periodic table; it has an atomic number of 92, an atomic

weight of 238.04, and valences of 3, 4, and 6. The average

abundance of U in the earth’s crust is 2.3 ppm, and in soils it

is 1.8 ppm. Concentrations of uranium in drinking waters

usually are expressed in terms of picocuries per liter, but that

is now being replaced by Becquerel per liter (Bq/L). The

approximate conversion factor, assuming equilibrium between 234U and 238U, is 1 g uranium equals 0.67 pCi. The

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

Joint Task Group: 20th Edition—See Section 3500-Al.

3500 OTHER METALS/Uranium

8
mean concentration of uranium in drinking water is 1.8 pCi/L.

The chief ore is uraninite, or pitchblende, uranous uranate

[U(UO4)2]. Uranium is known mainly for its use in the

nuclear industry, but has also been used in glass, ceramics,

and photography.

Uranium compounds are radioactive and are thereby toxic

by inhalation and ingestion. There are three natural radioisotopes of uranium. Uranium-238 has a half-life of 4.5 

109

years, represents 99% of uranium’s natural abundance,

and is not fissionable, but can be used to form plutonium-239,

which is fissionable. Uranium-235 has a half-life of 7.1  108

years, represents 0.75% of uranium’s natural abundance, is

readily fissionable, and was the energy source in the original

atomic bombs. Uranium-234 has a half-life of 2.5  105 years

and represents only 0.006% of uranium’s natural abundance.

The common forms in natural water are U4 and UO2

2. In

natural waters below pH 5, UO2

2 would dominate; in the pH

range of 5 to 10, soluble carbonate complexes predominate.

Although there is no U.S. EPA drinking water standard MCL

for uranium, an analysis for uranium is required if the gross

alpha activity of a water sample is greater than 15 pCi/L.

Perform analyses by the inductively coupled plasma/mass

spectrometry method (3125) or by one of the methods in 7500-U

(for regulatory compliance purposes).

3500 OTHER METALS/Uranium

9