QUALITY ASSURANCE PROGRAM
FOR THE ANALYSES OF CHEMICAL CONSTITUENTS
IN ENVIRONMENTAL SAMPLES*
The following program of quality assurance is for use by labora-
*
tories engaged in the analysis of organic and inorganic chemicals,
metals, and general analysis parameters in environmental simples,
Each laboratory is responsible for maintaining a continuing
record of the data from all quality control checks and for using
these data to make decisions on the acceptability of the analytical
results as they are acquired. All quality control data generated,
problems identified* and corrective actions taken to resolve the
problems are to be recorded and provided to the responsible authority
when reporting the analytical results. As available, quality control
(QC) check samples of known value and performance evaluation (PE)
samples should be analyzed by the laboratory prior to initiation of
.
the analytical program.
*
U. S. Environmental Protection Agency, Environmental Monitoring and
Support Laboratory, Cincinnati, Ohio, March, 1978

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A. Intra!aboratory Quality Control
As a part of its intra!aboratory analytical quality
control program, the laboratory must develop single labora-
tory precision and accuracy criteria for each parameter that
it is required to measure. These criteria must compare
favorably with published data. Initially, these data may
be applied over a broad concentration range. As more data
accumulate, the precision and accuracy of the method should
be updated and criteria developed for multiple narrower
ranges.
1. Precision - To determine the precision of the method,
a regular program of analyses of replicate aliquots
of environmental samples must be carried out. The
precision criterion should be developed from 15 sets of
replicate results accumulated over a period of time
during the routine analysis program. At least two
replicate aliquots of a well mixed sample must be
analyzed with each set of 20 samples or less analyzed
at a given time. These replicate data must be obtained
for each parameter of interest.

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Initially, samples selected for replicate analyses
should be those that are most representative of the inter-
ference potential of the sample type. For example,
in the current Effluent Guidelines Verification Program,
the influent to the treatment process would be appro-
priate. As the program progresses, samples representing
the entire range of concentrations and interference
potential should be designed into the replicate analyses
program.
After 15 replicate results have been obtained,
calculate the range (R .) of these results as follows:
Ri = JX1l " Xi2 I
where is the difference between the results of the
pair (X^ and X^) from sample i=l through n. The
concentration of each sample is represented by the mean:
X. = (Xil + Xi2^
I 2
where X^ is the average of the results of the replicate
pair. A preliminary estimate of the critical difference
(Rc) between replicate analyses for any specific concentration
level (C) can be calculated as:
n n _
R_ = 3.27 (C z R.)/(Z Xj.
i-11 i=r

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From these data develop a table of such Rc values for
various C values that span the concentration range of
interest.
These preliminary critical difference values may
be used to judge the acceptability of the succeeding
replicate results. To do this, calculate the mean (X")
and difference (R) between the replicate results. Refer-
ring to the table of critical range values developed
above, find the C nearest to X" and use its Rc to evaluate
the acceptability of R. If the R is greater than R ,
V
the system precision is out of control and the source
of this unusual variability should be identified and
resolved before continuing with routine analyses. Record
the results of all replicate analyses and periodically
(after 25 to 30 additional pairs of replicate results
are obtained) revise, update, and improve the table of
critical range values.
2. Accuracy - In addition to the initial determination
of the precision of the method, a program must be main-
tained to verify that the laboratory accuracy continues
under control. This program is concurrent to the spiked

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sample analysis program outlined below and is carried
out by preparing check standards and analyzing them
according to the method. The check standards should
be approximately equal to the concentration found in
routine samples. Alternately, one standard above and
one standard below the midpoint of the range of the method
should be used. Analyze the standard and calculate
0.. (the observed value). The percent recovery (P^)
is then calculated as follows:
100 (0.)
p. = 	1_
Ti
where T. = the true value.
After determining the for approximately 15 check
standards, calculate the mean (P) and standard deviation
(S ) of the percentages as follows:
H
n
and:
where n = the number of results available.

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If the percent recovery for succeeding check standards
is not within the interval of P" ± 2 Sp, the system should
be checked for problems. If problems exist, they must be
resolved before continuing with routine analysis. This
criteria is tighter than the generally accepted P ± 3 Sp
but will result in more accurate data for real samples if
these check standards are used to adjust the calibration
curve.
At least one check standard must be analyzed along
with each set of 20 samples or less that is analyzed
at a given time. This check standard data must be
obtained for each parameter of interest.
Record the recovery of all check standards and
periodically revise, update and improve the accuracy
criteria.
3. Recovery - Determine the recovery of the method for
the analysis of environmental samples by adding a
spike (T., true value) sufficient to approximately double
the background concentration level (X^) of the sample
selected earlier for replicate analysis (Section Al).
If the original concentration is higher than the midpoint
of the standard curve (range of the method), then the
concentration of the spike should be approximately one-half
the original concentration. If the concentration of the

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original sample was not detectable, the concentration
of the spike should be five to fifteen times the lower
limit of detection. The volume of standard added in
aqueous solution should not dilute the sample by more
than ten percent. The volume of standard added in an
organic solvent solution should be kept small (100 yl/1
or less), so that the solubility of the standard in the
water will not be affected.
Analyze the sample, calculate the observed value (Q,-),
and then calculate the recovery for the spike as follows:
where P.. is the percent recovery. If the sample was
diluted due to the addition of the spike, adjust
accordingly.
After determining for at least 15 spike results,
calculate the mean percent recovery (P) and standard
deviation (S ) of the recovery as follows:
P
P, = 100(0, - X.)/T,
n
? * (i PJ/n
i=T
where n = the number of percent recovery values available.

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If the percent recovery of the spike is not within
the interval of P" ± 3 Sp, the system accuracy is out of
control and the source of this systematic error should
be identified and resolved before continuing with routine
analysis.
At least one spiked sample must be analyzed along
with each set of 20 samples or less that is analyzed at
a given time. This spiked data must be obtained for
each parameter of interest. Record the recovery data of
all spiked analyses and periodically (every 25 to 30
data points) revise, update, and improve the accuracy
criteria.
B. Additional Routine Quality Control Practices
In addition to the foregoing formal quality control program,
certain other practices must be included during routine analyses
by the laboratory to eliminate determinate errors and to insure
the quality of the data. These practices include: instrument
calibration and performance checks, preparation and daily
check of calibration curves, method blank analyses, and
field blank analyses. Some of these operations are common
to all analytical methods and some are unique to specific
methods.

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For additional information and guidance in analytical
quality control practices refer to the U. S. Environmental
Protection Agency's "Analytical Quality Control Handbook" (1).
1. Operations Common to all Methods
a. Standard Curve - Prior to the analysis of samples,
a standard curve that covers the entire working
range of the method must be constructed with at
least five standards, including one near the upper
limit of the concentration range and one near the
lower limit of the concentration range. The other
standards should be equally spaced throughout the
operating concentration range.
Each day, if operation is continuous, or prior
to analyzing each group of samples, if operation is
non-continuous, analyze a minimum of two standards
to establish the validity of the original standard
curve. These standards should represent the range
of the standard curve, i.e., one above and one below
the midpoint of the standard curve. If these stan-
dards fall outside the established limits, a new
standard curve must be constructed. These limits

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should be established by the analyst as a part
of his ongoing quality control program,
b. Method Blank - A method blank must be determined
for each set of samples analyzed and whenever a
new source (new container) of reagent or solvent
is introduced into the analytical scheme. (NOTE:
the individual solvents and reagents should be
checked for purity prior to use in determining
the method blank or in the analysis of samples.)
To determine the method blank, take a quantity
of reagents equivalent to that used in the analysis
of the sample and carry them through the entire
analytical procedure including all glassware and
other materials that come into contact with the
sample. Determine a method blank for each class
of compounds to be determined, i.e., pesticides,
base-neutrals and acids, metals, phenolics, cyanides,
etc.
Reagents having background levels that interfere
with the compounds to be determined must be purified
and shown to be acceptable or replaced with some that

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are acceptable prior to proceeding with the analyses.
Problems encountered and corrective actions taken
should be reported to the responsible authority for
information and possible resolution of problems
encountered by other analysts,
c. Field Blanks - A field blank must be analyzed with
each set of samples from a given source. This is
particularly important whenever automatic samplers
are used for collection of samples as in the current
Effluent Guidelines Program. The blanks must be
analyzed in the same manner as the sample. Prepara-
tion of field blanks is described in the sampling
and analysis protocol (2). Field blanks for
purgeables are sent from the laboratory to the sampling
site and returned as a check on possible contamination
of the sample by permeation of volatiles through
the septum seal.
When interferences occur, the analytical
results must be discarded unless sufficient data
from these blanks is available to permit correction
of the results.

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2. Operations Specific to Organic Analysis by Gas
Chromatograph.y-Mass Spectroscopy (GC-MS)
a. Calibration Check for the GC-MS System - At the
beginning of each day's operation, test the calibration,
resolution, and sensitivity of the GC-MS system
as follows:
When analyzing for purgeable organics or semi-
volatile acids, check the system by directly injecting
and analyzing 100 nanograms of pentafluorobromobenzene
(PFBB)\ Determine system performance using the ion
abundance criteria for this compound listed in Table
1 (31). If this test shows that the system is not
properly calibrated retune and recalibrate to meet
specifications.
When determining semivolatile base-neutral
organics, check by injecting and analyzing 20 nano-
grams of decafluorotriphenylphosphine (DFTPP).
Determine the system performance using the ion abundance
criteria listed in Table 2 (4). If this test shows that
Available from Aldrich
^Available from PCR, Inc.

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the system is not properly calibrated, retune
and recalibrate to meet specifications,
b. Internal Standards - The use of internal standards
provides a convenient mechanism for checking
the total analytical procedure. Their use is recom-
mended when appropriate standards are available.
The internal standards should be selected by the
analyst based upon prior knowledge of the sample
source and type. They should be similar to the
compounds being determined, but not co-elute with
them. At least two internal standards should be
selected for each class of compounds of interest,
e.g., purgeables, pesticides, base-neutrals, and
acids, so that the retention time range of the
analysis is covered. Having selected the appropriate
internal standards, spike an aliquot of every sample
at the appropriate time, i.e., just prior to purging
the volatiles or just prior to extraction of pesticides,
base-neutrals, and the acids. If available, deuterated
compounds are recommended for use when analyzing by
GC-MS.

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c. Quantification by GC-MS - Using a GC-MS system,
e.g., Finnigan 1015 series or equivalent, pre-
pare a multi-point calibration curve for each
compound that is to be measured. This curve
should be sufficiently accurate to permit a rough
estimate of the concentration of the unknown for
several weeks. From this estimate, make up a
single concentration of standard for the compound
or compounds of interest and analyze on the same
day as soon as possible after the sample is
analyzed. The concentration of this standard
should be within a factor of two of the actual
concentration of the unknown and is used to cal-
culate an accurate estimate of the concentration
of the unknown.
Peak areas should be integrated using ion
abundances from two or more of the characteristic ions

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for the priority pollutants. The GC-MS system
must have a program capable of supporting this type
of integration.
(1) PROCEDURE
(a)	Prepare a minimum of three standard
solutions (10 ng/ul, 100 ng/ul, and 500 ng/ul
concentrations are suggested) of each of the
compounds that are to be measured. One or more
compounds may be present in the same standard
solution. Record the total ion current profiles
for each of the solutions, and integrate the
peak areas of the target compounds over two or
more of the selected characteristic ion abundances.
Prepare a separate plot of concentration versus
peak area for each ion and each compound.
(b)	As described earlier under b. 2. a. the
stability of the GC-MS total system must be
verified daily with the use of standard reference
materials, i.e., decafluorotriphenylphosphine,
pentafluorobromobenzene, and other standards
and calibration diagnostic programs. Whenever

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significant instability is observed, i.e.,
any random peak area change greater than
25% or any drift sufficient to require
recalibration of the mass scale, step (a)
must be repeated.
(c)	Measure the total ion current profiles
of the unknowns. Integrate the peak areas of
the target compounds over the characteristic
ion abundances. Using the calibration curves,
make a rough estimate of the concentration of
each of the unknowns using the appropriate
peak areas.
(d)	Prepare a standard solution for each
compound to be measured that day. The concentration
should be as close as possible to the concentration
of the unknown and always within at least a factor
of two. More than one compound may be in this
standard solution. Measure the total ion current
profiles of the standards. Perform peak area
integrations with the unknowns and standards using
two of the characteristic ions. Calculate the

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unknown concentration by interpolation of peak
areas and the known concentration of the stan-
dard. If the results are similar for the two
ions, report the average concentration. If
the results differ by more than 50%, select
another ion or ions until two are found that
give similar results.
(e)	For 10% of the samples, duplicate the
measurements of the unknowns and standards and
report both the unknown concentration measurements.
(f)	The data shown in Table 3 were obtained by
a single laboratory using the above procedure
with a series of blind spikes in water. The
average bias from the spiked value was-30%.
Inter!aboratory Quality Control
In addition to establishing the precision and accuracy
of the method and routinely analyzing replicate and spiked
samples, the laboratory must also analyze a quality control
(QC) check sample, at least twice annually, and a performance
evaluation (PE) sample, at least once annually, for para-
meters of interest as they are available from the

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Quality Assurance Branch, EMSL, Cincinnati. This is in
addition to the initial checks made before sample analyses
begin. These quality assurance samples will be forwarded
to the laboratory at the request of the responsible authority.
Samples currently available from EMSL - Cincinnati include:
pesticides, polychlorinated biphenyls (PCBs), purgeable
organics, metals, minerals, nutrients, and the demand series.
The results of the QC check sample should be recorded and
forwarded to the responsible authority. The results of the
PE samples should be recorded and forwarded to EMSL, Cincinnati,
Quality Assurance Branch.

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TABLE 1
PFBB Key Ions
Ion Abundance Criteria
Mass
Ion Abundance Criteria
78
less than 1% of base
peak
79
15-35% of base peak
80
4-8% of mass 79

116
less than 1% of base
peak
117
base peak

118
4-8% of mass 117

166
less than 1% of base
peak
167
65-85% of base peak

168
5-9% of mass 167

245
less than 1% of base
peak
246
75-98% of base peak

247
5-9% of mass 246

248
75-98% of base peak

249
5-0% of mass 248

Mass 248 must be 93-99% of mass 246

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TABLE 2
DFTPP Key Ions and Ion Abundance Criteria
Mass
Ion Abundance Criteria

51
30-60% of mass 198

68
less than 2% of mass 69

70
less than 2% of mass 69

127
40-60% of mass 198

197
less than 1% of mass 198

198
base peak, 100% relative
abundance
199
5-9% of mass 198

275
10-30% of mass 198

365
1% of mass 198

441
less than mass 443

442
greater than 40% of mass
198
443
17-23% of mass 442


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TABLE 3
Example of Quantitative Data Obtained With GC-MS by a Single Laboratory
Using a Single External Standard
Reported Value	True Value	%
Semi volatile Organics	ug/liter	yg/1iter Deviation
Solvent Extract Sample 1
trichlorobenzene	0.3	0.79	-62
n-octadecane	1.4	2.17	-35
pentachlorophenol	0.5	0.75	-33
fluoranthene	1.5	2.97	-49
di-(2-ethylhexyl)phthalate	1.3	1.42	- 9
Solvent Extract Sample 2
trichlorobenzene	0.5	0.79	-37
n-octadecane	0.6	0.87	-31
pentachlorophenol	1.5	1.76	-15
fluoranthene	0.5	0.71	-30
di-(2-ethylhexyl)phthalate	2.5	3.57	-30
Solvent Extract Sample 3
trichlorobenzene	0.6	0.79	-24
n-octadecane	2.2	3.25	-32
pentachlorophenol	6.2	3.77	+64
fluoranthene	1.4	2.38	-41
di-(2-ethylhexyl)phthalate	0.8	0.71	+13
Volatile Organics Sample 1
Chloroform	6.3	10.7	-41
1,2-dichloroethane	1.3	1.05	+24
carbon tetrachloride	^1	1.86	-46
dichlorobromomethane	0.6	0.81	-26
dibromochloromethane	0.7	1-03	-32
bromoform	2.3	4.81	-52
Volatile Organics Sample 2
Chloroform	69.2	74.6	- 7
1,2-dichloroethane	3.4	3,06	+11
carbon tetrachloride	^5	3.87	+29
dichlorobromomethane	lo.l	9-15	+1°
dibromochloromethane	6.4	7-12	~10
bromoform	7_2	9.23	-22

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References
1.	"Handbook for Analytical Quality Control in Water and Wastewater
Laboratories", June, 1972. Available from U. S. Environmental
Protection Agency, Environmental Monitoring and Support Laboratory,
Cincinnati, Ohio, 45268. New edition in press, to be available
Fall, 1978.
2.	"Sampling and Analysis Procedures for Screening of Industrial
Effluents for Priority Pollutants", U. S. Environmental Protection
Agency, Environmental Monitoring and Support Laboratory, Cincinnati,
Ohio, 45268, April, 1977.
3.	Budde, W. L., and Eichelberger, J. W., U. S. Environmental Protec-
tion Agency, Environmental Monitoring and Support Laboratory,
Cincinnati, Ohio, 45268.
4.	Eichelberger, J. W., Harris, L. E., and Budde, W. L., Anal. Chem.
47, 995 (1975).

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