ASTM D5673-96

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Designation: D 5673 – 96
Standard Test Method for
Elements in Water by Inductively Coupled Plasma—Mass
Spectrometry
This standard is issued under the fixed designation D 5673; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
TABLE 1 Recommended Analytical Mass and Estimated
1. Scope
Instrument Detection Limits
1.1 This test method covers the determination of dissolved
Recommended Estimated Instrument
Element
elements in ground water, surface water, and drinking water. It A
Analytical Mass Detection Limit, μg/L
may also be used for the determination of total-recoverable
Aluminum 27 0.05
elements in these waters as well as wastewater.
Antimony 121 0.08
Arsenic 75 0.9
1.2 This test method should be used by analysts experienced
Barium 137 0.5
in the use of inductively coupled plasma—mass spectrometry
Beryllium 9 0.1
(ICP-MS), the interpretation of spectral and matrix interfer-
Cadmium 111 0.1
ences and procedures for their correction. Chromium 52 0.07
Cobalt 59 0.03
1.3 It is the user’s responsibility to ensure the validity of the
Copper 63 0.03
test method for waters of untested matrices.
Lead 206, 207, 208 0.08
Manganese 55 0.1
1.4 Table 1 lists elements for which the test method applies,
Molybdenum 98 0.1
with recommended masses and typical estimated instrumental
Nickel 60 0.2
detection limits using conventional pneumatic nebulization.
Selenium 82 5.0
Silver 107 0.05
Actual working detection limits are sample dependent and, as
Thallium 205 0.09
the sample matrix varies, these detection limits may also vary.
Thorium 232 0.03
In time, other elements may be added as more information
Uranium 238 0.02
Vanadium 51 0.02
becomes available and as required.
Zinc 66 0.2
1.5 This standard does not purport to address all of the
A
Instrument detection limits (3s) estimated from seven replicate scans of the
safety concerns, if any, associated with its use. It is the
blank (1 % v/v HNO ) and three replicate integrations of a multi-element standard.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
3.2 Definitions of Terms Specific to This Standard:
bility of regulatory limitations prior to use.
3.2.1 calibration blank—a volume of water containing the
same acid matrix as the calibration standards (see 11.1).
2. Referenced Documents
3.2.2 calibration shock solution—a solution prepared from
2.1 ASTM Standards:
the stock standard solution(s) to verify the instrument response
D 1066 Practice for Sampling Steam
with respect to analyte concentration.
D 1129 Terminology of Terms Relating to Water
3.2.3 calibration standards—a series of known standard
D 1192 Specification for Equipment for Sampling Water
solutions used by the analyst for calibration of the instrument
and Steam in Closed Conduits
(that is, preparation of the analytical curve) (see Section 11).
D 1193 Specification for Reagent Water
3.2.4 dissolved—those elements that will pass through a
D 3370 Practices for Sampling Water from Closed Con-
0.45-μm membrane filter.
duits
3.2.5 instrumental detection limit—the concentration
equivalent to a signal which is equal to three times the standard
3. Terminology
deviation of the blank signal at the selected analytical mass(es).
3.1 Definitions—For definitions of other terms used in this
3.2.6 internal standard—pure analyte(s) added in known
test method, refer to Terminology D 1129.
amount(s) to a solution. This is used to measure the relative
instrument response to the other analytes that are components
1 of the same solution. The internal standards must be analytes
This test method is under the jurisdiction of ASTM Committee D-19 on Water
that are not a sample component.
and is the direct responsibility of Subcommittee D19.05 on Inorganic Constituents
in Water.
3.2.7 method detection limit—the minimum concentration
Current edition approved Feb. 10, 1996. Published April 1996.
of an analyte that can be identified, measured and reported with
EPA Test Method: Determination of Trace Elements in Waters and Wastes by
99 % confidence that the analyte concentration is greater than
Inductively Coupled Plasma—Mass Spectrometry, Method 200.8.
Annual Book of ASTM Standards, Vol 11.01. zero. This confidence level is determined from analysis of a
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 5673
TABLE 2 Recommended Analytical Isotopes and Additional
sample in a given matrix containing the analyte(s).
Masses That Are Recommended To Be Monitored
3.2.8 quality control reference solution—a solution with the
A
Isotope Element of Interest
certified concentration(s) of the analytes, prepared by an
independent laboratory, and used for a verification of the 27 Aluminum
121, 123 Antimony
instrument’s calibration.
75 Arsenic
3.2.9 reagent blank—a volume of water containing the
135, 137 Barium
9 Beryllium
same matrix as the calibration standards, carried through the
106, 108, 111, 114 Cadmium
entire analytical procedure.
52, 53 Chromium
3.2.10 total-recoverable—a term relating to forms of each
59 Cobalt
63, 65 Copper
element that are determinable by the digestion method included
206, 207, 208 Lead
in this procedure (see 12.2).
55 Manganese
3.2.11 tuning solution—a solution that is used to determine
95, 97,98 Molybdenum
60, 62 Nickel
acceptable instrument performance prior to calibration and
77, 82 Selenium
sample analysis.
107, 109 Silver
203, 205 Thallium
4. Summary of Test Method
232 Thorium
238 Uranium
4.1 This test method describes the multi-element determi-
51 Vanadium
nation of trace elements by inductively coupled plasma—mass
66, 67, 68 Zinc
83 Krypton
spectrometry (ICP-MS). Sample material in solution is intro-
99 Ruthenium
duced by pneumatic nebulization into a radiofrequency plasma
105 Palladium
where energy transfer processes cause desolvation, atomiza-
118 Tin
tion, and ionization. The ions are extracted from the plasma
A
Isotopes recommended for analytical determination are underlined. These
through a differentially pumped vacuum interface and sepa- masses were recommended and are reflected in the precision and bias data.
Alternate masses may be used but interferences must be documented.
rated on the basis of their mass-to-charge ratio by a quadrupole
mass spectrometer. The ions transmitted through the quadru-
pole are detected by a continuous dynode electron multiplier
All data obtained under such conditions must be corrected by
assembly and the ion information processed by a data handling
measuring the signal from another isotope of the interfering
system. Interferences relating to the technique must be recog-
element and subtracting the appropriate signal ratio from the
nized and corrected for (see Section 7 on interferences). Such
isotope of interest. A record of this correction process should
corrections must include compensation for isobaric elemental
be included with the report of the data. It should be noted that
interferences and interferences from polyatomic ions derived
such corrections will only be as accurate as the accuracy of the
from the plasma gas, reagents, or sample matrix. Instrumental
isotope ratio used in the elemental equation for data calcula-
drift as well as suppressions or enhancements of instrument
tions. Relevant isotope ratios and instrument bias factors
response caused by the sample matrix must be corrected for by
should be established prior to the application of any correc-
the use of internal standardization.
tions.
5. Significance and Use
6.1.2 Abundance Sensitivity—Abundance sensitivity is a
property defining the degree to which the wings of a mass peak
5.1 The test method is useful for the determination of
contribute to adjacent masses. The abundance sensitivity is
element concentrations in many natural waters and wastewa-
affected by ion energy and quadrupole operating pressure.
ters. It has the capability for the determination of up to 20
Wing overlap interferences may result when a small ion peak
elements. High analysis sensitivity can be achieved for some
is being measured adjacent to a large one. The potential for
elements that are difficult to determine by other techniques.
these interferences should be recognized and the spectrometer
6. Interferences
resolution adjusted to minimize them.
6.1 Several types of interference effects may contribute to 6.1.3 Isobaric Polyatomic Ion Interferences—Isobaric poly-
inaccuracies in the determination of trace elements. These atomic ion interferences are caused by ions consisting of more
interferences can be summarized as follows: than one atom that have the same nominal mass-to-charge ratio
6.1.1 Isobaric Elemental Interferences—Isobaric elemental as the isotope of interest, and which cannot be resolved by the
interferences are caused by isotopes of different elements mass spectrometer in use. These ions are commonly formed in
the plasma or interface system from support gases or sample
which form singly or doubly charged ions of the same nominal
mass-to-charge ratio and which cannot be resolved by the mass components. Most of the common interferences have been
spectrometer in use. All elements determined by this test identified, and these are listed in Table 3 together with the
method have, at a minimum, one isotope free of isobaric method elements affected. Such interferences must be recog-
elemental interference. Of the analytical isotopes recom- nized, and when they cannot be avoided by the selection of an
mended for use with this test method (see Table 2), only alternative analytical isotope, appropriate corrections must be
molybdenum-98 (ruthenium) and selenium-82 (krypton) have made to the data. Equations for the correction of data should be
isobaric elemental interferences. If alternative analytical iso- established at the time of the analytical run sequence as the
topes having higher natural abundance are selected in order to polyatomic ion interferences will be highly dependent on the
achieve greater sensitivity, an isobaric interference may occur. sample matrix and chosen instrument conditions.
D 5673
TABLE 3 Common Molecular Ion Interferences
effects), at the point of aerosol formation and transport to the
Background Molecular Ions plasma (for example, surface tension), or during excitation and
A
ionization processes within the plasma itself. High levels of
Molecular Ion Mass Element Interference
dissolved solids in the sample may contribute deposits of
+
NH 15 .
+
OH 17 . material on the extraction, or skimmer cones, or both, reducing
+
OH 18 .
the effective diameter of the orifices and, therefore, ion
+
C 24 .
+ transmission. Dissolved solids levels not exceeding 0.2 %
CN 26 .
+
CO 28 . (w/v) have been recommended to reduce such effects. Internal
+
N 28 .
standardization may be effectively used to compensate for
+
N H 29 .
+ many physical interference effects. Internal standards should
NO 30 .
+
NOH 31 . have similar analytical behavior to the elements being deter-
+
O 32 .
mined.
+
O H 33 .
36 + 6.1.5 Memory Interferences—Memory interferences result
ArH 37 .
36 +
ArH 39 . when isotopes of elements in a previous sample contribute to
40 +
ArH 41 .
the signals measured in a new sample. Memory effects can
+
CO 44 .
+ result from sample deposition on the sampler and skimmer
CO H 45 Sc
+ +
ArC , ArO 52 Cr
cones, and from the buildup of sample material in the plasma
+
ArN 54 Cr
torch and spray chamber. The site where these effects occur is
+
ArNH 55 Mn
+
dependent on the element and can be minimized by flushing the
ArO 56 .
+
ArOH 57 .
system with a rinse blank consisting of HNO (1+49) in water
40 36 +
Ar Ar 76 Se
between samples. The possibility of memory interferences
40 38 +
Ar Ar 78 Se
40 +
should be recognized within an analytical run and suitable rinse
Ar 80 Se
times should be used to reduce them. The rinse times necessary
Matrix Molecular Ions
for a particular element should be estimated prior to analysis.
Chloride
35 + This may be achieved by aspirating a standard containing
ClO 51 V
35 +
ClOH 52 Cr
elements corresponding to ten times the upper end of the linear
37 +
ClO 53 Cr
range for a normal sample analysis period, followed by
37 +
ClOH 54 Cr
35 +
analysis of the rinse blank at designated intervals. The length of
Ar Cl 75 As
37 +
Ar Cl 77 Se
time required to reduce analyte signals to within a factor of ten
Sulphate
of the method detection limit should be noted. Memory
32 +
SO 48 .
32 +
interferences may also be assessed within an analytical run by
SOH 49 .
34 +
SO 50 V, Cr
using a minimum of three replicate integrations for data
34 +
SOH 51 V
acquisition. If the integrated signal values drop consecutively,
+ +
SO ,S 64 Zn
2 2
32 +
the analyst should be alerted to the possibility of a memory
Ar S 72 .
34 +
Ar S 74 .
effect, and should examine the analyte concentration in the
Phosphate
previous sample to identify if this was high. If a memory
+
PO 47 .
+
interference is suspected, the sample should be re-analyzed
POH 48 .
+
PO 63 Cu
2 after a long rinse period.
+
ArP 71 .
Group I, II Metals
7. Apparatus
+
ArNa 63 Cu
+
ArK 79 .
7.1 Inductively Coupled Plasma–Mass Spectrometer—
+
ArCa 80 .
Instrument capable of scanning the mass range 5 to 250 amu
B
Matrix Oxides
with a minimum resolution capability of 1 amu peak width at
TiO 62 to 66 Ni, Cu, Zn
ZrO 106 to 112 Ag, Cd
5 % peak height. Instrument may be fitted with a conventional
MoO 108 to 116 Cd
or extended dynamic range detection system. See manufactur-
A
Method elements or internal standards affected by molecular ions.
ers instruction manual for installation and operation.
B
Oxide interferences will normally be very small and will only impact the method
elements when present at relatively high concentrations. Some examples of matrix
8. Reagents
oxides are listed of which the analyst should be aware. It is recommended that Ti
and Zr isotopes be monitored if samples are likely to contain high levels of these
8.1 Purity of Reagents—Reagent grade chemicals shall be
elements. Mo is monitored as a method analyte.
used in all tests. Unless otherwise indicated, it is intended that
reagents shall conform to the specifications of the committee
6.1.4 Physical Interferences—Physical interferences are as-
on analytical reagents of the American Chemical Society,
sociated with the physical processes that govern the transport
of the sample into the plasma, sample conversion processes in
th
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