ASTM D5810-96(2001)
(Guide)Standard Guide for Spiking into Aqueous Samples
Standard Guide for Spiking into Aqueous Samples
SCOPE
1.1 This guide covers the general technique of "spiking" a broad range of materials into aqueous media. This guide will serve the analyst in preparing spiked samples for quality control purposes. Guidance is also provided to aid the analyst in calculating recoveries and interpreting results. It is the responsibility of the analyst to determine whether the procedures and materials described here are appropriate to the task at hand.
1.2 The procedures in this guide are focused on "matrix spike" preparation, analysis, and interpretation of results. The applicability of these procedures to the preparation of calibration standards, calibration check standards, laboratory control standards, reference materials, and other quality control materials by spiking is incidental. A sample (the matrix) is fortified (spiked) with the analyte of interest for a variety of analytical and quality control purposes. While the spiking of multiple sample portions is discussed, the method of standard additions is not covered.
1.3 This guide is intended for use in conjunction with the individual analytical test method that provides procedures for analysis of the analyte or component of interest. The test method is used to determine an analyte or component's background level and, again after spiking, its now elevated level. Each test method typically provides procedures not only for samples, but also for calibration standards or analytical control solutions, or both. These procedures include preparation, handling, storage, preservation, and analysis techniques. These procedures are applicable by extension, using the analyst's judgement on a case-by-case basis, to spiking solutions, and are not reiterated in this guide. See also Practice E200 for preparation and storage information.
1.4 These procedures apply only to analytes that are soluble in water at the concentration of the spike plus any background material, or to analytes soluble in a solvent that is itself water-soluble. The system used in the later case must result in a homogeneous solution of analyte and sample. Meaningful recovery data cannot be obtained if an aqueous solution or homogenous suspension of the analyte of interest in the sample cannot be attained. These procedures may be applicable to microbiological preparations if the homogeneity of the suspension can be adequately maintained throughout the course of the analysis, for example, by mechanical agitation or stirring.
1.5 Matrix spiking may be performed in the field or in the laboratory, depending on which part of the analytical process is to be tested. Field spiking tests the recovery of the overall process, including preservation and shipping of the sample. Laboratory spiking tests the laboratory process only. Spiking of sample extracts, concentrates, or dilutions will test only that portion of the process subsequent to addition of the spike.
1.6 The values stated in SI units are to be regarded as the standard.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D 5810–96 (Reapproved 2001)
Standard Guide for
Spiking into Aqueous Samples
This standard is issued under the fixed designation D 5810; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope recovery data cannot be obtained if an aqueous solution or
homogenoussuspensionoftheanalyteofinterestinthesample
1.1 This guide covers the general technique of “spiking” a
cannot be attained. These procedures may be applicable to
broad range of materials into aqueous media. This guide will
microbiologicalpreparationsifthehomogeneityofthesuspen-
serve the analyst in preparing spiked samples for quality
sioncanbeadequatelymaintainedthroughoutthecourseofthe
control purposes. Guidance is also provided to aid the analyst
analysis, for example, by mechanical agitation or stirring.
in calculating recoveries and interpreting results. It is the
1.5 Matrix spiking may be performed in the field or in the
responsibility of the analyst to determine whether the proce-
laboratory,dependingonwhichpartoftheanalyticalprocessis
dures and materials described here are appropriate to the task
to be tested. Field spiking tests the recovery of the overall
at hand.
process, including preservation and shipping of the sample.
1.2 The procedures in this guide are focused on “matrix
Laboratoryspikingteststhelaboratoryprocessonly.Spikingof
spike” preparation, analysis, and interpretation of results. The
sample extracts, concentrates, or dilutions will test only that
applicability of these procedures to the preparation of calibra-
portion of the process subsequent to addition of the spike.
tion standards, calibration check standards, laboratory control
1.6 The values stated in SI units are to be regarded as the
standards, reference materials, and other quality control mate-
standard.
rials by spiking is incidental.Asample (the matrix) is fortified
1.7 This standard does not purport to address all of the
(spiked) with the analyte of interest for a variety of analytical
safety concerns, if any, associated with its use. It is the
and quality control purposes. While the spiking of multiple
responsibility of the user of this standard to establish appro-
sample portions is discussed, the method of standard additions
priate safety and health practices and determine the applica-
is not covered.
bility of regulatory limitations prior to use.
1.3 This guide is intended for use in conjunction with the
individual analytical test method that provides procedures for
2. Referenced Documents
analysis of the analyte or component of interest. The test
2.1 ASTM Standards:
method is used to determine an analyte or component’s
D1129 Terminology Relating to Water
background level and, again after spiking, its now elevated
D1193 Specification for Reagent Water
level. Each test method typically provides procedures not only
D3694 Practices for Preparation of Sample Containers and
for samples, but also for calibration standards or analytical
for Preservation of Organic Constituents
control solutions, or both. These procedures include prepara-
D3856 Guide for Good Laboratory Practices in Laborato-
tion, handling, storage, preservation, and analysis techniques.
ries Engaged in Sampling and Analysis of Water
These procedures are applicable by extension, using the
D4375 Practice for Basic Statistics in Committee D19 on
analyst’s judgement on a case-by-case basis, to spiking solu-
Water
tions, and are not reiterated in this guide. See also Practice
E200 Practice for Preparation, Standardization, and Stor-
E200 for preparation and storage information.
age of Standard and Reagent Solutions for Chemical
1.4 These procedures apply only to analytes that are soluble
Analysis
in water at the concentration of the spike plus any background
material, or to analytes soluble in a solvent that is itself
3. Terminology
water-soluble. The system used in the later case must result in
3.1 Definitions—For definitions of terms used in this guide,
a homogeneous solution of analyte and sample. Meaningful
refer to Terminology D1129.
This guide is under the jurisdiction ofASTM Committee D19 on Water and is
the direct responsibility of Subcommittee D19.02 on General Specifications,
Technical Resources, and Statistical Methods. Annual Book of ASTM Standards, Vol 11.01.
Current edition approved Jan. 10, 1996. Published March 1996. Annual Book of ASTM Standards, Vol 11.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 5810–96 (2001)
3.2 Definitions of Terms Specific to This Standard: Training of field personnel and validation of their spiking
3.2.1 matrix spike, n—the quantity (mass) of a component techniques are necessary to ensure that spikes are added
(analyte) of interest that is added to a sample (matrix) in order accuratelyandreproducibly.Duplicatefieldspikescanbeused
to test the bias as measured by recovery (of that component to document the reproducibility of the technique. When envi-
under specific analytical conditions) and reported as percent ronmentally labile compounds are used as spikes, the spiking
recovery (P). solutionshallbeprotecteduptothepointofusebyappropriate
3.2.2 spike, v—the addition of a known amount of an meanssuchaschilling,protectionfromsunlightandoxygen,or
analyte of known identity to a measured volume of a sample chemical preservation.
(from a specific matrix) to determine the efficiency with which
NOTE 1—Anyfieldspikedsample,ifknowntothelaboratory,shouldbe
the added analyte can be “recovered” from (measured in) that
labeledasafieldspikeinthefinalresultsreport.Also,wheneverpossible,
matrix by the analytical system after exposure to a specific
field spiking of volatile compounds should be avoided.
portionofananalyticalprocess.Matrixspikingisaprocessfor
5.5 It is often tacitly assumed that an analyte component is
accomplishing this. The precision and bias estimates from
recovered from samples to approximately the same extent that
several trials under specific analytical conditions represent the
a spike of the same analyte is recovered from a spiked sample.
measurement efficiency with which the analyte may be deter-
One reason that this assumption may be incorrect is that the
mined under these conditions.
spike may not be bound up in the sample (for example, with
3.2.3 spiking solution—the solution in which one or more
suspended matter) in the same way that the naturally occurring
spikes are dissolved (along with any necessary preservatives).
analyte is bound in the sample. The spike may therefore be
This solution acts as a carrier to provide ease of measurement
recovered from the sample differently than the background
and more rapid and thorough mixing of the spike into the
level of the analyte. It is not good practice to correct analytical
sample, as compared to adding the spike as a pure compound.
data using spike recoveries for this reason, as well as the fact
that bias corrections can add variability. However, spike
4. Summary of Guide
recovery information should be reported along with related
4.1 This guide describes a technique for the addition of a
sample analysis results.
known amount of an analyte to an aqueous sample.Appropri-
5.6 This guide is also applicable to the use of spikes for
ate concentrations of the spike relative to the original concen-
quantification by the method of standard additions and to the
tration in the sample are discussed. Applications of the tech-
addition of surrogates and internal standards.
nique and aids in the interpretation of results obtained are
described.
6. Apparatus
5. Significance and Use 6.1 Pipetters—Plunger-actuated pipetters, to dispense small
volumesofspikesolutions.Thesemustbecalibratedandtested
5.1 Matrix spiking is commonly used to determine the bias
carefully for repeatability before use.
under specific analytical conditions, or the applicability of a
6.2 Volumetric Transfer Pipets—Class A, used to deliver
test method to a particular sample matrix in that context, by
knownvolumesofsampleandtoaddlargervolumesofspiking
determining the extent to which the spiked analyte or compo-
solutions.
nent is recovered from the sample matrix under these condi-
6.3 Volumetric Flasks—Class A volumetric flasks may be
tions. Reactions or interactions of the analyte or component of
used to measure known volumes of sample.
interestwiththesamplematrixmaycauseasignificantpositive
6.4 Balance—An analytical (0.1-mg), semimicro (0.01-
or negative effect on recovery and may render the chosen
mg), or micro (0.001-mg) balance.
analytical, or monitoring, process ineffectual for that sample
matrix.
7. Reagents
5.2 Matrix spiking can also be used to monitor the perfor-
7.1 Purity of Reagents—At a minimum, reagent grade
mance of a laboratory, individual instrument, or analyst as part
chemicals shall be used in all spike preparations. Reagents of
of a regular quality assurance program. Changes in spike
thehighestavailablepurityshallbeusedforspikeanalytesand
recoveriesorrecoverylimitsfromthesameorsimilarmatrices
demonstrated to be free of interfering substances for the
over time may indicate variations in the quality of analytical
subsequent tests to be performed. If possible, a primary
results.
standard grade shall be used. Unless otherwise indicated, it is
5.3 Spiking can be used to compare the recoveries of like
intended that all reagents conform to the specifications of the
spikes from reagent water samples and natural matrix samples
Committee on Analytical Reagents of the American Chemical
(measured with and without spike) to distinguish between (1)
Society. Other grades may be used, provided that the reagent
unusual interference and (2) inherent method recovery and
isofsufficientlyhighpuritytopermititsusewithoutadversely
instability effects. This guide does not attempt to deal with the
statistical significance of differences in spike recoveries from
different matrices.
5.4 Special precautions shall be observed when nonlabora-
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
tory personnel perform spiking in the field. It is recommended
listed by the American Chemical Society, see Analar Standards for Laboratory
thatallspikepreparationworkbeperformedinalaboratoryby
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
experienced analysts so that the field operation consists solely
and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
of adding a prepared spiking solution to the sample matrix. MD.
D 5810–96 (2001)
affecting the bias and precision of subsequent determinations. 9.2 Performananalysisonatleastoneportionofthesample
Purchasedspikingsolutionsshallbedemonstratedtobefreeof to estimate the concentration of the component(s) of interest.
substancesthatwouldinterferewithsubsequentanalysesbeing
9.3 Use the result of this analysis to determine the appro-
performed, and the supplier’s stated concentration shall be
priate amount of spike and spiking solution to be added to the
verified by analysis prior to use. Compensatory errors associ-
sample. If this is not possible (such as when spiking in the
atedwithself-referencingshouldbepreventedbyusingspiking
field),estimatetheconcentrationsofthecomponentsofinterest
solutions of a standard originating from a source, when
based on prior knowledge of the sample source.
available, different from that of the routine method calibration
9.3.1 To be of maximum value for quantification of the
standards.
analyte(s) or for the evaluation of method accuracy, the
7.2 Purity of Water—Unlessotherwiseindicated,references
concentration in the spiked sample should be at least double,
to water shall be understood to mean reagent water as defined
but ideally not over five times, the concentration of the analyte
by the individual test method to be used to analyze a sample
in the unspiked sample, as long as the total analyte concentra-
after spiking. If more than one test method is to be used, the
tion can be brought within the test method’s dynamic range.
minimum criteria of each test method must be met. If test
Spike concentrations below this range lead to highly variable
method reagent water specifications are not available, refer-
spike recoveries, as described in Section 11. Higher spike
ences to water shall be understood to mean reagent water as
concentrationsmaymasktheeffectthatrealinterferences,such
defined byType I of Specification D1193 and demonstrated to
as matrix effects, are having on the analyte at its background
be free of interfering substances for the test(s) being per-
levels,leadingtoover-optimisticestimatesofanalyterecovery.
formed.
9.3.2 If the spiked component is not present in the sample,
7.3 Solvents—Spectroscopic, high-pressure liquid chroma-
but is added only to validate the recovery of an analytical
tography(HPLC),orultrapuregrademethanolispreferablefor
method, the concentration after spiking should be at least five
use as a solvent for relatively water-insoluble components in
times the detection limit of the method or a concentration of
most trace-organic analyses. Other water-soluble solvents may
interest to the data user, whichever is greater.
be useful as solvents for certain analytes. Most inorganic
spiking solutions are prepared in water or dilute aqueous acid
9.4 Determine the volume of the portion of sample to be
solution. Solvents shall be checked before use by analysis for
spiked, depending on such factors as the sample volume
interfering substances.
required by the analytical method to be used, convenience of
7.4 Spiking Solutions—Spiking solutions of each analyte of
dilution factors, and amount of sample available.
interest are prepared individually or in combination, either
9.5 Prepare a spiking solution of suitable concentration
gravimetricallyorvolumetrically.Thepreservationandstorage
using the appropriate solvent as described in 7.4.
criteria found in the applicable analytical test method for its
9.5.1 Pertinent factors in determining the appropriate con-
calibration or check standards apply likewise to spiking solu-
centration of the spiking solution are as follows:
tions. The stability of a stored spiking solution should be
9.5.1.1 The desired final concentration of the spike in the
verified routinely by the appropriate dilution of a portion of
sample;
spiking solution to the laboratory’s analyte concentration of
9.5.1.2 Theworkingcalibrationrang
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