EPA-680/4-75-007
JUNE 1975
Environmental Monitoring Series
PRELIMINARY MILK REPORT
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
LAS VEGAS, NEVADA 89114
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Develop-
ment, U. S. Environmental Protection Agency, have been
grouped into five series. These five broad categories
were established to facilitate further development and
application of environmental technology. Elimination of
traditional grouping was consciously planned to foster
technology transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL MONI-
TORING series. This series describes research conducted
to develop new or improved methods and instrumentation
for the identification and quantification of environ-
mental pollutants at the lowest conceivable significant
concentrations. It also includes studies to determine
the ambient concentrations of pollutants in the environ-
ment and/or the variance of pollutants as a function of
time or meteorological factors.
EPA REVIEW NOTICE
This report has been reviewed by the National Environ-
mental Research Center-Las Vegas, EPA, and approved for
publication. Approval does not signify that the contents
necessarily reflect the views and policies of the U.S.
Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorse-
ment or recommendation of use.
Document is available to the public for sale through
the National Technical Information Service, Springfield,
Virginia 22161.
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EPA-680/4-75-007
June 1975
PRELIMINARY MILK REPORT
by
Arthur N. Jarvis and David G. Easterly
Quality Assurance Branch
Technical Support Laboratory
National Environmental Research Center
Las Vegas, Nevada
ROAP 21BEK/22AAJ
Program Element 1HA327
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
LAS VEGAS, NEVADA 89114
-------
ABSTRACT
A summary of the results of the milk cross-check program from
July 1973 through November 1974 is given. These data indicate a need
for improvement in the laboratory analysis of both beta and gamma-
emitting radionuclides in milk, Also, the expected relationship, i.e.,
with increasing sample activity the accuracy of the analysis should
improve, was not seen with any consistency at the levels of activity
used in these studies. Accurate analysis of strontium-89 was particu-
larly difficult for most laboratories to achieve, while the accurate
analysis of cesium-137 was the least difficult.
These results exemplify the need for improvement in analytical
procedures through the adoption of standard reference methods, more
frequent calibration and maintenance of counting instruments, improved
quality control practices within each laboratory, and greater partici-
pation in laboratory intercomparison studies conducted by the National
Bureau of Standards, the Energy Research and Development Administration,
and the U.S. Environmental Protection Agency.
iii
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CONTENTS
Page
Abstract • H*
List of Tables and Figures v
Introduction *
Methods and Procedures 2
Results and Discussion 3
Summary 6
References 31
APPENDIX. Statistical Calculations 32
1v
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TABLES
Number Page
1 Summary of Cross-Check Programs ... 8
2 Summary of Milk Analysis Data, July 1973 to
November 1974 9
3 Limits Established by the Analytical Quality
Control Service 12
4 Results of Milk Cross-Check Analyses, July 1973
to November 1974 12
FIGURES
Number Page
1 Sample Analysis and Report of Participant's Data .... 13
2 Control Chart 15
3-A Histogram of Monthly Analysis for Strontium-89 17
3-B Histogram of Monthly Analysis for Stront1um-90 20
3-C Histogram of Monthly Analysis for Sarium-140 23
3-D Histogram of Monthly Analysis for Iodine-131 25
3-E Histogram of Monthly Analysis for Cesium-137 28
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PRELIMINARY MILK REPORT
INTRODUCTION
Environmental radiation measurements are made daily by federal,
state, local, and private agencies. The data obtained from these
measurements are utilized by the U.S. Environmental Protection Agency
(EPA) and other agencies for such purposes as estimating dose and
health effects, establishing standards and guides, and conducting
regulatory activities. It is therefore imperative that the precision
and accuracy of the data be assured so that policy decisions concerning
environmental quality are based on valid and comparable data.
The present radiation quality assurance program of the EPA is
designed to encourage the development and implementation of quality
control procedures at all levels of sample collection, analysis, data
processing, and reporting. As an integral part of the EPA's program,
the Quality Assurance Branch of the National Environmental Research
Center-Las Vegas (NERC-LV) distributes calibrated radionuclide solutions
for instrument calibration and chemical yield determinations, and con-
ducts a number of laboratory performance studies involving the analysis
of radionuclides in environmental media.
The intercomparison studies program enables participating labora-
tories to maintain checks on their analyses and assists them in docu-
menting the validity of their data. In addition, this program enables
the EPA to obtain an overall estimate of the precision and accuracy of
environmental radiation measurements, or more precisely the precision
and accuracy of laboratory radioassay procedures of environmental
samples.
-------
Studies currently in progress involve samples of most environmental
media and include milk, air, water, soil, diet, urine, and noble gases.
Table 1 is a summary of the cross-check programs. Participants include
nuclear facilities or their contractors, state, federal, and inter-
national laboratories. The number of participants has increased
steadily during the past two years. Because of the large number of
participants and the continuing nature of the programs, sufficient
data are generated to enable valid periodic statistical assessment
of the quality of environmental data.
Laboratories perform the analyses and return their data to the
Quality Assurance Branch for statistical analysis. Comparisons are
made between laboratories and within an individual laboratory for
accuracy and precision. A computer report and a periodically updated
performance chart are returned to each participant. This enables each
laboratory to document the precision and accuracy of its radiation
data, to identify instrumental and procedural problems, and to compare
performance with other laboratories.
METHODS AND PROCEDURES
Through December 1973, reconstituted powdered milk was used in the
milk cross-check program. Two modifications were made to the program
beginning 1n 1974: (1) fresh, whole, pasteurized, homogenized milk
was used in preparing the samples, and (2) sample distribution was
changed from monthly to a bimonthly basis.
The milk was prepared for distribution by thoroughly mixing with
10 ml/gallon of formalin and 3.79 ml/gallon of antifoaming agent
(Dow Corning Antifoam,R FG-10 Emulsion, Food Grade). Three aliquots
were gamma counted for background determination. The remaining milk
was "spiked" using calibrated solutions of the radionuclides. The milk
was again thoroughly mixed and three aliquots taken for gamma analysis.
If these results Indicated homogeneity, the milk was packaged for
-------
shipment. A 4-liter sample containing strontium-89, strontium-90,
cesium-137, iodine-131, and barium-140 was distributed to each of
approximately 35 participating laboratories.
Each participating laboratory made three independent determinations
for each radionuclide included in the particular cross-check sample and
reported its results to the Quality Assurance Branch. Control limits
(sigma limits) previously established by the Analytical Quality Control
Service in Winchester, Massachusetts, were used in analyzing the quality
of the results obtained by these laboratories (1,2). These limits were
based on the purpose for which the data were being obtained and on
reasonable laboratory ability. Upon receipt of the reports from all
participating laboratories, the data were transferred to punch cards
and analyzed using a CDC 6400 computer. This analysis included determi-
nation of the experimental average and standard deviation of the sample,
the normalized range, standard error normalized deviation, experimental
sigma, and the grand average of all laboratories for each radionuclide.
Examples of sample calculations to illustrate the computations per-
formed by the computer are shown in the appendix.
A report was generated containing the data reported by all par-
ticipating laboratories, listed according to their identity code, along
with the results of the data analysis. Examples are shown in Figure 1.
In addition, a control chart was generated for each radionuclide in-
cluded in the sample (Figure 2). The control charts are updated each
time a laboratory participates in a cross-check study, thus giving each
laboratory a continuous record of its performance.
A copy of the computer printout and a control chart for each radio-
nuclide is mailed to each participant approximately two weeks following
the report due date.
RESULTS AND DISCUSSION
A summary of the results of the milk analysis data is shown in
Table 2. All participants received samples containing strontium-89,
3
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strontium-90, cesium-137, iodine-131, and barium-140; however, all did
not submit results for each analysis. This resulted in a different
number, N, being reported for the various radionuclides.
A comparison may be made between the experimental standard devia-
tion, s, calculated from the data supplied by the participating labora-
tories (Table 2) and the standard deviation, a, expected for various
analyses listed in Table 3.
For the purpose of comparison, the experimental [(s/known)100] and
expected [(a/known)100] standard deviations, expressed as a percent of
the known values, are shown for each month in Table 2. The experimental
standard deviation divided by the known value (s/p) indicates no im-
provement in the analytical results when whole milk was used instead
of powdered.
Figure 3-A shows the results in the form of a histogram for the
strontium-89 analysis by month.* The February results were the poorest
over the period for which strontium-89 data were analyzed. When com-
paring the grand average (X) to the known value (u), a negative bias
was observed for all monthly samples except February. No explanation
for either the negative bias or the poor analytical performance by the
participating laboratories is readily apparent. It is now necessary
to determine if this is due to the analytical method(s) being used and
if so if a different method of analysis or modification of the existing
method(s) is warranted.
The monthly results of the strontium-90 analysis are shown in
Figure 3-B. On an average the (s/y) values were lower and the devia-
tions from y were less than for strontium-89 analysis. Even though
the results show some inconsistency from month to month, in general
they may be viewed with some optimism since data for at least one
* For all data used in this report, Chauvenet's criterion was used as
the basis for acceptance or rejection of the X value of each laboratory.
-------
month are sufficiently accurate to indicate good results are attainable.
More frequent calibration and maintenance of counting instruments, im-
proved quality control practices within the laboratories, and greater
participation in laboratory intercomparison studies may be beneficial
for some of the laboratories having analytical difficulties.
The monthly results of the barium-140 analysis are shown in Figure
3-C. Because of the manufacturer's production schedules and the half-
life of barium-140, some monthly cross-check samples did not contain
this isotope. Unlike strontium-89 and 90, generally no "wet" chemistry
is involved in the barium-140 analysis. Most analysts determine the
gamma emitters by gamma spectroscopy. This would indicate errors arise
from improper, infrequent, or erroneous calibration; faulty or inade-
quate instrumentation; or erroneous processing and interpretation of
data. Participants obtaining inaccurate results for their barium
analysis should restandardize and calibrate their instruments more
frequently using the same geometry as that used for sample counting.
It appears from this limited amount of data that the barium-140 results
are better in terms of accuracy and (s/y) than the strontium analysis.
The monthly results of the iodine-131 analysis are shown in Figure
3-D. These results are as good as the barium-140 results in terms of a
small deviation from y, and are better than the barium-140 results in
terms of s/y. With proper calibration and interpretation, accurate
results appear readily attainable. During the six-month period where
reconstituted powdered milk was used, the results were relatively good,
with two of the six analyses having an experimental sigma value of
less than 10 pCi/liter. Results were the best for the September
sample.
The monthly results of the cesium-137 analysis are shown in Figure
3-E. These results are considerably better in terms of the ratio s/y
than those for any of the other radionuclides used in the milk cross-
check program. The reason for the better results with cesium may be
partially attributed to the fact that many participants standardize
their instruments with a cesium-137 source. The cesium-137 peak area
-------
may also be somewhat easier defined than the iodine-131 and barium-140
peaks. Even better results for cesium-137 analysis could be attained
if improvement was made by a few of the participants, This may best be
accomplished through consultation with the laboratories having the
analytical problem.
Table 3 gives the limits previously established by the Analytical
Quality Control Service (1,2). During the period July 1973 to November
1974, with few exceptions, results from the milk cross-check program
did not approach these established limits. Examination of these results
reveals that 29% of the participants were within the plus or minus
3 sigma control limits for the strontium-89 analysis, 42% for the
strontium-90, 52% for barium-140, 60% for iodine-131, and 77% for
cesium-137 (Table 4).
SUWARY
Data compiled for the milk cross-check program from July 1973 to
November 1974 indicate the need for improvement in analytical procedures
for all radionuclides studied. Accurate analysis of strontium-89 was
particularly difficult for most laboratories to achieve, while the
accurate analysis of cesium-137 was the least difficult.
It is hoped that results similar to those obtained for cesium-137
can be accomplished for analysis of the other radionuclides. The data,
although generally having relatively large measures of random devia-
tions, indicate this may be possible for all except strontium-89.
There was at least one month where the experimental sigma approached
the established limits for all radionuclides except strontium-89. In
September 1973 the cesium-137 experimental sigma was less than the
established limits. These data would indicate the laboratories can
achieve good accuracy for most of the samples being analyzed.
Two things are apparent from these data. The expected relation-
ship, i.e., the accuracy of the analysis should improve with increas-
ing sample activity, was not seen with any consistency at the levels
-------
of activity used in the studies (Table 2). There is a need for con-
siderable improvement in the laboratory analysis of both beta and gamma-
emitting radionuclides in milk.
One reason for the variability in the results may be due to the
expansion of the milk cross-check program to include new participants.
The number of participants more than doubled during the first half
of 1973. As these laboratories become more familiar with the analysis,
hopefully the accuracy of the results will improve. For strontium-89,
and possibly strontium-90, it appears that new methods of analysis
should be evaluated since less than a third of the participating labora-
tories are doing a satisfactory job of strontium-89 analysis and less
than half for strontium-90. If data over the next several months indi-
cate that the present limits are unrealistic for some radionuclides
and cannot be attained by the majority of participants, then the limits
should be made more realistic. Available information does indicate
good internal precision for most laboratories, but poor accuracy in
many cases. This exemplifies the need for improvement in analytical
procedures through the adoption of standard reference methods and
protocols for establishing equivalency to the reference method, more
frequent calibration and maintenance of counting instruments, improved
quality control practices within each laboratory, and greater partici-
pation in laboratory intercomparison studies conducted by the National
Bureau of Standards, the Energy Research and Development Administration,
and the Environmental Protection Agency.
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Table 1. SUMMARY OF CROSS-CHECK PROGRAMS*
SAMPLE
Milk
Water
Gross a, 6*
Gamma
3H
239pu*
226Ra
Air
Gross a, 0*
239pu*
Soil*
Diet
Urine
Gas
ANALYSIS
89Sr, 9<>Sr> 131If
137Cs, '""Ba, K
Gross o, B
60Co, 106Ru, 134Cs,
137Cs. 51Cr. 65Zn
3H
239pu
226Ra
a.' B» Y
239Pu
239pu
89Sr, 9°Sr, 1311,
137Cs. li.OBa. K
3H
85Kr
ACTIVITY
PER ISOTOPE
< 200 pCi/1
< 100 pCi/1
< 500 pCi/1
< 3500 pCi/1
< 10 pCi/1
< 20 pCi/1
< 200 pCi /sample
< 2 pCi/sample
< 50 pCi /sample
< 200 pCi/kg
< 3500 pCi/1
< 20 pCi/ml
QUANTITY
SUPPLIED
^ 4 liters
^ 4 liters
^ 4 liters
•v 60 ml
^ 4 liters
\> 4 1 i ters
3 - 2" or 4"
diam. air filters
3 - 2" or 4"
diam. air filters
-b 100 g
3 - 4-liter
samples
•v 60 ml
10 liters
PRESERVATIVE
Formalin
0.5 N HN03
0.5 N HN03
none
0.5 N HN03
0.5 N HN03
none
none
none
Formalin
Formalin
none
DISTRIBUTION
Bimonthly
Bimonthly
Bimonthly
Bimonthly
Semiannual ly
Quarterly
Quarterly
Quarterly
Semi annually
Quarterly
Quarterly
Semiannual ly
TIME FOR
ANALYSIS
& REPORT
6 weeks
4 weeks
4 weeks
4 weeks
8 weeks
6 weeks
4 weeks
6 weeks
8 weeks
8 weeks
4 weeks
8 weeks
00
* Laboratories are required to have the necessary licenses before receiving these samples.
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Table 2. SUMMARY OF MILK ANALYSIS DATA, JULY 1973 TO NOVEMBER 1974
\0
Oul'73
Aug'73
Sep'73
Oct'73
Nov'73
Dec '73
Feb'74
Apr'74
Jul'74
Sep'74
Nov'74
Strontlum-89
Known pCi /liter
1 a limit pCi /liter
1 a/known %
N
X pCi/liter
s pCi /liter
s/known %
98
5
5.1
17
87.2
11.0
11.2
96
5
5.2
14
61.5
29.6
30.8
85
5
5.9
13
76.9
12.3
14.5
133
7
5.3
19
112.3
25.4
19.1
123
6
4.9
16
98.3
24.9
20.2
89
5
5.6
18
69.5
30.8
34.6
83
5
6.0
23
92.6
44.0
53.0
204
10
4.9
28
171.9
36.7
18.0
151
8
5.3
26
128.1
27.6
18.3
157
7.9
5.0
23
137.8
25.7
16.4
172
8.6
5.0
30
137.3
39.1
22.7
Strontium-90
Known pCi/liter
1 o limit pCi/liter
1 o/known %
N
55 pCi/liter
s pCi /liter
s/known %
65
3
4.6
23
64.0
8.3
12.8
158
8
5.1
17
130.4
44.5
28.2
72
4
5.6
16
67.6
6.4
8.9
119
6
5.0
23
106.1
19.9
16.7
135
7
5.2
22
115.2
26.9
19.9
103
5
4.9
22
93.1
16.4
15.9
198
10
5.1
21
182.7
20.0
10.1
172
9
5.2
31
169.9
22.9
13.3
152
8
5.3
29
152.7
28.8
18.9
124
6.2
5.0
28
124.1
15.6
12.6
102
5.1
5.0
33
94.1
15.2
14.9
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Table 2 (continued). SUMMARY OF MILK ANALYSIS DATA, JULY 1973 TO NOVEMBER 1974
Jul'73
Aug'73
Sep'73
Oct'73
Nov'73
Dec' 73
Feb'74
Apr' 74
Jul'74
Sep'74
Nov'74
Barium- 140
Known pCi/ liter
1 a limit pCi/liter
1 a/known %
N
X pCi/liter
s pCi/liter
s/known %
148
7
4.7
27-
152.6
11.0
7.4
152
8
5.3
21
158.4
24.9
16.4
146
7
4.8
22
145.3
27.9
19.1
104
5
4.8
32
107.4
19.2
18.5
0
0
159
8
5.0
35
159.3
11.9
7.5
0
0
193
9.6
5.0
33
195.2
21.9
11.3
0
Iodine- 131
Known pCi/liter
1 a limit pCi/Hter
1 a/known %
N
X pC1/liter
s pCi/liter
s/known %
115
6
5.2
33
125.1
18.3
15.9
144
7
4.9
22
147.8
13.7
9.5
123
6
4.9
22
121.3
8.8
7.2
493
25
5.1
34
486.3
28.2
5.7
104
5
4.8
26
99.7
11.0
10.6
177
9
5.1
25
175.8
9.6
5.4
150
8
5.3
40
149.9
27.7
18.5
150
8
5.3
41
154.6
20.7
13.8
142
7
4.9
35
145.8
15.9
11.2
188
9.4
5.0
31
192.2
20.4
10.9
126
6.3
5.0
36
122.4
10.5
8.3
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Table 2 (continued). SUMMARY OF MILK ANALYSIS DATA, JULY 1973 TO NOVEMBER 1974
Jul'73
Aug'73
Sep'73
Oct'73
Nov'73
Dec '73
Feb'74
Apr'74
Jul'74
Sep'74
Nov'74
Cesium- 137
Known pCi/liter
1 o limit pCi/liter
1 o/known %
N
X pCi/Hter
s pCi/liter
s/ known %
116
6
5.2
34
116.5
6.6
5.7
122
6
4.9
22
120.1
7.7
6.3
84
5
6.0
22
81.6
3.9
4.6
91
5
5.5
35
88.7
8.5
9.3
126
7
5.6
28
123.1
9.3
7.4
101
5
5.0
30
100.1
9.4
9.3
214
11
5.1
38
208.9
12.7
5.9
174
9
5.2
42
171.1
16.1
9.3
155
8
5.2
37
157.3
10.0
6.5
126
6.3
5.0
35
132.2
7.6
6.0
101
5.1
5.0
38
102.8
5.6
5.5
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Table 3. LIMITS ESTABLISHED BY THE ANALYTICAL
QUALITY CONTROL SERVICE
Radionucl ide
131J
137 Cs
'""Ba
89Sr
90 Sr
la Limits for Single Determination
For Levels <100 pCi/1 iter
(pCi /liter)
5
5
5
5
For Levels <30 pCi /liter
1.5
For Levels >100 pCi/liter
(X)
5
5
5
5 -
For Level s >30 pCi/1 iter
(*)
1.5
Table 4. RESULTS OF MILK CROSS-CHECK ANALYSES,
JULY 1973 TO NOVEMBER 1974
Radionucl ide
a Limits
<1
<2
<3
>3
89Sr
90Sr
llt0Ba
131J
137Cs
Laboratories Within a Limits (%)
11.2
20.7
28.5
71.5
19.4
31.6
42.4
57.6
25.3
42.9
52.0
48.0
29.7
49.9
59.7
40.3
39.0
63.1
76.7
23.3
12
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NERC-LV RADIONUCLIDES IN MILK CROSS-CHECK PROGRAM — JUNE 1975
6/15/75 SAMPLE - A 137CS
KNOWN VALUE = 101 PCI/L
EXPECTED LABORATORY PRECISION (IS, 1 DETERMINATION) = 5.1 PCI/L
EXPERIMENTAL RNG ANLY NORMALIZED DEVIATION
LAB RESULT SIGMA (R + SR) AVERAGE (GRAND AVG) (KNOWN)
D 98
D 102
D 102 2.3 .46 101 -.7 -.1
P NO DATA PROVIDED
Q 104
Q 104
Q 108 2.3 .46 105 .9 1.5
R 95
R 99
R 93 3.1 .69 96 -2.4 -1.8
S 108
S 105
S 106 1.5 .35 106 1.2 1.8
V 96
V 110
V 98 7.6 2.18 101 -.5 .1
EXPERIMENTAL SIGMA (ALL LABS) = 7 GRAND AVERAGE = 103
* - NOT USED FOR CALCULATING GRAND AVERAGE
** - INSUFFICIENT INFORMATION TO CALCULATE
Figure 1. Sample Analysis and Report of Participant's Data
13
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Explanation of terms in Figure 1:
Title:
Column 1:
Colume 2:
Column 3:
Columns 4
and 5:
Column 6:
Column 7:
Column 8:
Bottom of
Chart:
Program name, sample collection date, sample code
letter, analysis type, known concentrations of radio-
nuclide, expected standard deviation of analysis -
single determination.
Laboratory identification code (A, B, C, etc.).
Laboratory results (0-25 results listed down column).
Is (standard deviation) of the experimental results.
Normalized range value in "mean range + standard error
of the range" (R + aR units for comparability. (See
Statistical Techniques for Quality Control of Environ-
mental Badioaasay, AQCS Report Stat-1. November 1964,
pages 4-8.) (Sp = c^ for printing purposes.)
Average value.
Normalized deviation from the grand average value of
all laboratories expressed in a^ units.
Normalized deviation from the known value expressed in
cfy units.
Is experimental error of all laboratories, and the
grand average of all laboratories.
14
-------
RADIONUCLIDES IN MILK CROSSCHECK PROGRAM
LAB - D 137CS
NORMALIZED DEVIATION FROM KNOWN
1973 1974
1U
9
8
7
6
5
4
3
s 2
' 1
® o
M
A -1
-2
-3
-4
-5
-6
-7
-8
-9
_m
.
L* r-f i A
FA f\ ;^
V^ / L_j
A/
*
>»-^ — J^v
^" X
N^^x^ w
CL
WL
WL
CL
NORMALIZED RANGE
1973 1974
R +5
R +2
R +1
R +0
O
.
J F M A M J
I
J A
_J
1
.1 . 1 •
SONDJ FMAHJJASUND
CL
WL
Figure 2. Control Chart
15
-------
Explanation of terms used in the control chart (Figure 2).
Title: Name of program, laboratory code letter, and type
of analysis.
Upper Graph: "Normalized deviation from known versus the month
of analysis." [The 95.0% (y ± 2 M) and the 99.7%
(y ± 3aM) confidence levels were chosen as the
warning levels and control limits respectively.]
Lower Graph: "Normalized range values (R + OR) versus the
month of analysis." [The 97.5% (R + 2cR) and
^100% (R + 3aR) confidence levels were chosen as
the warning levels and control limits respec-
tively.]
16
-------
STRONTIUM-89 IN MIX
JULY 1973
FREQ.
5 .
4 .
3 -
2 -
1 .
0
U -
x" =
s =
i i i i
0 10 20
98
87.
11.0
|
30
pCi/liter
2
|
"
..
| |
40
I i
50
I
60
I I I I I I I I I
50 60 70 80 90 100 110 120 130 140 150 160
CONCENTRATION IN pCi/liter
FREQ.
FREQ.
5..
4 . .
3 --
2 -.
1 4.
0
STRONTIUM-89 IN MIX
AUGUST 1973
Jl = 96 pCi/liter
X = 615
S = 296
X
+
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160
CONCENTRATION IN pCi/liter
5 ..
4 . .
3 --
2-.
1 ..
0 _
STRONTIUM-89 IN MILK
SEPTEMBER 1973
U = 85 pCi/liter
X" = 76.9 "
S = 12 3
I I I I I 111
I I I I I I
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160
CONCENTRATION IN pCi/liter
5 ..
4 ..
FREQ. 3 . .
2 -.
1 . .
o L
STRONTIUM-89 IN MILK
OCTOBER 1973
L| = 133 pCi/liter
X = 112.3
S = 254
I I I I I I I I I I I I
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160
CONCENTRATION IN pCi/liter
Figure 3-A. Histogram of Monthly Analysis for Strontium-89
17
-------
5 , .
4 . .
FREQ. 3 . .
2 - .
1 . .
o L
STRONTIUM-89 IN MILK
NOVEMBER 1973
U, « 123 pCi/liter
X = 98.3
S = 24 9
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160
CONCENTRATION IN pCi/titer
STRONTIUM-89 IN MILK
5 . .
4 . .
FREQ 3 . .
2. .
1 . .
0
DECEMBER 1973
LI » 89 pCi/litef
7 = 69 5 •
S = 308
0 10 20 30 40 5C 60 70 80 90 100 110 120 130 140 150 160
CONCENTRATION IN pCi/liter
STRONTIUM-89 IN MILK
FEBRUARY 1974
6- -
5- - L) = 83 pCi/liter
FREQ 4-- x = 926 •
3T
2-
1
° I ' ' I I I I I I I I I I I I I I I I | | I ^^ I I I ff I I I I | I I I
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230
CONCENTRATION IN pCi/liter
STRONTIUM-89 IN MILK
APRIL 1974
6- -
5- . L| = 204 pCi/liter
FREO 4- . X = 171 9
3- • S = 36 7
2- -
o'l I I I I I I I | I | I I I
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140' 150' 160 ' 170' 180' «o' 200 210'220 '230
11'' r^rtJrTvl~"^^~^W~^^~H-^^-
CONCENTRATION IN pCi/liter
Figure 3-A. Histogram of Monthly Analysis for Strontium-89 (continued),
18
-------
FREQ.
STRONTIUM-89 IN MILK
JULY 1974
6 "" LI = 151 pCi/liter
4 -~ X = '28.1 ••
27,6
3--
2- -
o'l I | I I I I I I I I I B I I I ^^ m-^^-^^ff fl I I I I M M | M
0 10 20 30 40 50 60 70 80 90 100 "0 120 130 140 150 160 170 180 190 200 210 220 230
CONCENTRATION IN pCi/liter
STRONTIUM-89 IN MILK
FREQ
SEPTEMBER 1974
JJ = 157 pCi/liter
137.8
6--
5--
4- -
3-- S = 257
2- -
1 - -
0 < | I I I I I I—| I I I I | I i i—fiii—i—n—i—i ' « i i t «—i i i i i i i i i i i i T—r
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230
CONCENTRATION IN pCi/liter
STRONTIUM-89 IN MILK
FREQ
6- -
i".
3- -
NOVEMBER 1974
U - 172 pCi/liter
X = 137 3 -
S = 39.1 -
1 I I | I | I I I | I
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160' 170'
CONCENTRATION IN pCi/liter
I I I I M
190 200 210 220 230
Figure 3-A. Histogram of Monthly Analysis for Strontium-89 (continued).
19
-------
STRONTIUM-90 IN MILK
FRED
JULY 1973
i i i i
0 10 20 30 40 50 60 70 80 90 WO 110 120 130 140 150 160 170 180 190 20C 210 220
CONCENTRATION IN pCi/liter
FREQ
STRONTIUM-90 IN MILK
AUGUST 1973
L4 = 158 pCi/liter
)T = 130.4
S = 44.5
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 20C 210 220
CONCENTRATION IN pCi/liter
FREQ
STRONTIUM-90 IN MILK
SEPTEMBER 1973
6 -
5 -
4 -
3 -
2 -
1 .
0
(
U = 72 pCi/liter
X = 67.6
S = 64
i 1 I I I i | | i
i
1 1 1 1 1 1 T 1 1 1
3 10 20 30 40 50
I I I
I I I I I I 1 I I I
I •! I 1 I I I I I | |l
70 80 90 100 110 120 130 140 150 160 170 180 190 20C 210 220
CONCENTRATION IN pCi/liter
STRONTIUM-90 IN MILK
FREQ
6 --
5 --
4 --
3 --
2 --
1 --
0
0
OCTOBER 1973
L| - 119 pCi/liter
X = 106.1
S = 19.9
I I I I I I I I I I I I |l
10 20 30 40 50 60 70 80 90 WO 110 120 130 140 150 160 170 180 190 20C 210 220
CONCENTRATION IN pCi/liter
Figure 3-B. Histogram of Monthly Analysis for Strontium-90
20
-------
STRONTIUM-90 IN MILK
FREQ.
6 --
5 --
4 - -
3 --
2 --
1 -j-
0
NOVEMBER 1973
Lj = 135 pCi/liter
X = 115.2
S - 26.9
10
20 30 40 50 60 70 80 90 CO 110 120 130 140 150 160 170 180 190 20C 210 220
CONCENTRATION IN pCi/liter
FREQ
FREQ.
STRONTIUM-90 IN MILK
DECEMBER 19/3
M = 103 pCi/liter
X = 93.1
S = 16 4
I I I
0 10 20 30 40 50 60 70 80 90 CO 110 120 130 140 150 160 170 180 190 20C 210 220
CONCENTRATION IN pCi/liter ,
STRONTIUM-90 IN MILK
6 - -
5 --
4 - -
3 •-
2 --
1 - -
o L-
FEBRUARY 1974
M = 198 pCi/liter
X = 1827 ••
S = 20.0
I I I .11 I I I I I I I I I I I I I I I I I I I I
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 15O 160 170 180 190 20C 210 220
CONCENTRATION IN pCi/liter
STRONTIUM-90 IN MILK
FREO
6 --
5 --
4 --
3 --
2 --
1 --
o L.
APRIL 1974
U, = 172 pCi/liter
3? = 169.9 ••
S = 22.9 "
-H-
0 10 20 30 40 50 60 70 80 90 OO 110 120 130 140 150 160 170 180 190 20C 210 220
CONCENTRATION IN pCi/liter
Figure 3-B. Histogram of Monthly Analysis for Strontium-90 (continued),
21
-------
FREQ
FREQ
STRONTIUM-90 IN MILK
JULY 1974
6 I L| = 152 pCi/liter
5 •- X = 1527
3 " S = 288
2 •-
0 T| | | | | | | | | |
0 10 20 30 40 50 60 70 80 90 XX) HO 120 130 140 150 160 170 180 190 20C 210 220
CONCENTRATION IN pCi/liler
STRONTIUM-90 IN MILK
SEPTEMBER 1974
6 • - H = 124 pCi/liter
4 . _ X = 124.1
3 - - s = 15.6
2 :-
1 . -
0 I I I I I I I I I I I I I I I
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 20C 210 220
CONCENTRATION IN pCi/liter
FREO.
STRONTIUM-90 IN MILK
NOVEMBER 1974
I I I I I I I I I I I I I I I I I I II
10 20 30 40 50 60 70 80 90 100 HO 120 130 140 150 160 170 180 190 20C 210 220
CONCENTRATION IN pCi/liler
Figure 3-B. Histogram of Monthly Analysis for Strontium-90 (continued)
22
-------
BARIUM-MO IN MILK
FREQ.
JULY 1973
L| = 148 pCi/liter
3< = 152.6 ••
S = 11.0
I I I i I
I I I I I I I I
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230240
CONCENTRATION IN pCi/litec
BARIUM-140 IN MILK
FREQ
FREQ.
AUGUST 1973
7 -
6 •
5 -
4 -
3 -
2 -
1 „
0
M • '52
pCi/liter
\ 7 = 158.4
S = 24.9
I-Ul I J I 4.
i-L I I
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230240
CONCENTRATION IN pCi/l.ter
BARIUM-140 IN MILK
7 ••
6 --
5 --
4 - -
3 --
2 --
1 - -
o L_i
SEPTEMBER 1973
U • 146 pCi/Uter
X = 145 3
S = 27.9
-M-4
40 5O 60 70 60 90 100 110 120 130 140 (50 160 170 180 190 200 210 220 230240
CONCENTRATION IN pCi/liter
BARIUM-(40 IN MILK
M I -t I .41 M M I I I I
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230240
CONCENTRATION IN pCi/liter
Figure 3-C. Histogram of Monthly Analysis for Barium-140
23
-------
BARIUM-140 IN MILK
FREQ.
FEBRUARY 1974
7 • •
6 --
5 -•
4 - -
3 --
2 --
1 - -
LJ = 159 pCi/liter
>T = 159-3 "
S = 1V9
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230240
CONCENTRATION IN pCi/liter
BARIUM-140 IN MILK
7 -•
6 --
FFREQ. 4 "
3 --
2 --
1 - -
0 -
SEPTEMBER 1974
Lj = 193 pCi/liter
X - 195.2
S = 21 9
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230240
CONCENTRATION IN pCi/liter
Figure 3-C. Histogram of Monthly Analysis for Barium-140 (continued).
24
-------
IODINE-131 IN MILK
FREQ.
FREQ.
JULY
9 -
8 -
7 -
6 -
5 -
4 -
3 -
2 -
1 -
n
1973
U =
X =
s =
115
125
18.3
pCi/liter
1
.
, J
M M I I I I I M I I I I I I
90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250
CONCENTRATION IN pCi/lrter
IODINE-131 IN MILK
AUGUST 1973
9 -
8 - -
7 - -
6 - -
5 - -
4 - -
3 - -
2 - -
1 - -
0 I—"
L| = 144 pCi/liler
H. = 147.8
S = 13.7
I I I I I 1 I I I 1 I I I I I
I I I I I I I I I I I I
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250
CONCENTRATION N pCi/liter
FREQ.
IODINE-131 IN MILK
SEPTEMBER 1973
9 - •
8 - -
7 - -
6 - -
5 - •
4 - -
3 - -
2 - -
1 - -
0 -
\\
123 pCi/liter
= 121.3
S = 8.8
I I I I I I I I I I I
40 50 60 70 80
90 100 110 120 130 140 150 160 170 180 190 200 210 220 2-30 240 250
CONCENTRATION IN pCi/liter
FREQ.
9
8
7
6
5
4 4-
3 - .
2 -.
OCTOBER 1973
U = 493 pCi/liter
X = 4863
S = 282
420 430 440 450 460 470 480 490 500 510 520 530 540 550 560
CONCENTRATION IN pCi/liter
Figure 3-D. Histogram of Monthly Analysis for Iodine-131
25
-------
IOOINE-131 IN MILK
NOVEMBER 1973
9 - • H = 104 pCi/liter
7 " ! "X • 99 7
6 - - S = 11 0
5 - •
FREO. 4 . .
3 - -
2 - -
1 - -
0 ' I I I I I I
I I I I I I I I I I I I I I I I I I I I I I I
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250
CONCENTRATON N pCi/liter
IODINE-131 IN MILK
DECEMBER 1973
9 - • L| - 177 pCi/liter
7 '. '. ^ = 1/58 "
FREQ. 65:: s = 96 •'
4 . .
3 - -
2 - -
1 - -
0 ' | | I I I I t I I | I I I I I I I I I I I '
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250
CONCENTRATION IN pCi/liter
IODINE-131 IN MILK
FEBRUARY 1974
U - 150 pCi/liter
7 * 149 9 ••
8-27-7 "
I I I I I I I I I
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250
CONCENTRATION IN pCi/liter
IODINE-131 IN MILK
APRIL 1974
9 -•
8 • •
7 - •
FREO. | " ~
4 • •
3 - -
2 - -
o T
D = 150 pCi/liter
X = 154.6
S - 20 7
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220
CONCENTRATION IN pCi/liter
230 240 250
Figure 3-D. Histogram of Monthly Analysis for Iodine-131(continued).
26
-------
FREQ. « "*"
4 ..
3 --
2 --
1 --
IOOINE-131 IN MILK
JULY 1974
9 .- L| - 142 pCi/liter
8 •- X = 1458 - "
7 + S = 159
I I I I I >
I I I I I I ^^^—^^^^^^^^^^^^^^^^—^—I—(—f—
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 2-30 240 250
CONCENTRATION IN pCi/liter
IODINE-131 IN MILK
SEPTEMBER 1974 _
9 • •
8 - -
FREQ. I " ;
4 - -
3 - -
2 --
LJ = 188 pCi/liter
X = 1922 "
S • 20.4
*
JLJL-i j
' I I'll 1H~^^^T~f~+•
•1 I I I I I I I I | I I I I I I
40 50 60 70 80 90 100 110 120 130 140 150 160 170 160 190 200 210 220 230 240 250
CONCENTRATION IN pCi/Mer
IODINE-131 IN MILK
NOVEMBER 1974
9 • •
FREQ.
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 2-30 240 250
CONCENTRATION IN pCi/liter
Figure 3-D. Histogram of Monthly Analysis for Iodine-131 (continued),
27
-------
CESIUM-137 IN MILK
JULY 1973
FREQ.
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240
CONCENTRATION IN pCi/liter
CESIUM-137 IN MILK
AUGUST 1973
12
11
10
9
8
FREQ. 7
6
5
4
3
2
1
0
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240
CONCENTRATION IN pCi/liter
CESIUM-137 IN MILK
SEPTEMBER 1973
• • U « 84 pCi/liter x
7 = 816 •• I
- • S = 3.9
M I I I I I I I M I I I I I I I I I I I I M I I
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240
CONCENTRATION IN pCi/liter
CESIUM-137 IN MILK
OCTOBER 1973
FREQ
I I I I I I I I I I I I I I I I I I I I I I I I
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240
CONCENTRATION IN pCi/liter
Figure 3-E. Histogram of Monthly Analysis for Cesium-137
28
-------
CESIUM-137 IN MILK
12 - -
FREQ
FREO.
FREQ
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240
CONCENTRATION IN pCi/liter
CESIUM-137 IN MILK
DECEMBER 1973
I I I I I I I I I I I I I I t I I I I I I I t
40 50 60 70 80 90 100 110 120 130 HO 150 160 170 180 190 200 210 220 230 240
CESIUM-137 IN MILK
CONCENTRATION IN pCi/liter
12
11
10
9
8
FREO 7
6
5
4
3
2
1
0
FEBRUARY 1974
(Lj = 214pCi/liter
"X » 2089 "
S = 127 "
I I I I i I I 1 I II I I I I I I I I I .....
40 50 60 70 80 90 100 110 120 130 140 )50 160 170 180 190 200 210 220 230 240
CONCENTRATION IN pCi/liter
CESIUM-137 IN MILK
12
11
10
9
8
7
6
5
4
3
2
1
0
APRIL 1974
174 pCi/liter
171.1
16.1
I ( I I I I I I I I I I I I I I I I
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240
CONCENTRATION IN pCi/liter
Figure 3-E. Histogram of Monthly Analysis for Cesium-137 (continued)
29
-------
CESIUM-137 IN MILK
JULY 1974
12 - -
11 - -
9 -.
8 . .
FREQ. 6 '. ".
5 - -
4 . .
3 - -
2 - -
U = 155 pCi/Uter
S = W.O
| | | | I I I I I | | I I I I I I I
40 50 60 70 80 90 100 110 120 130 140 ISO 160 170 180 190 200 210 220 230 240
CONCENTRATION IN pCi/liler
CESIUM-137 IN MLK
SEPTEMBER 1974
' ' L| = 126 pCi/liter
10 - • 3( = 1323
9 . .
8 - .
9 - • S - 7.6
FREQ. I
6 - -
5 . .
4 - -
3 - -
2 - -
1 - -
I I I I I |^PPPPPM-M-I I I I I I M I
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240
CONCENTRATION IN pCi/liter
CESIUM-137 IN MIX
NOVEMBER 1974
12 J-
11 - - |J * 101 pCi/litef
10 - •
9 - .
8 -. 5=56
FREQ. I ' •
6 - *
5 --
4 . .
3 - -
2 - -
X = 1028
M I I M I I I I F^^^^-t-l I I I II I I I I I I I M I I I I M I
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240
CONCENTRATION IN pCi/liler
Figure 3-E, Histogram of Monthly Analysis for Cesium-137 (continued),
30
-------
REFERENCES
1. F. Knowles, "Interlaboratory Study of Iodine-131, Cesium-137,
Barlun-140, Strontium-89, and Strontium-90 Measurements in Milk,
May-July 1970," Technical Experiment 70-MKAQ-l, Analytical Quality
Control Service, Bureau of Radiological Health (1970).
2. F. Knowles, "Rapid Field Method for Radiostrontium in Milk,"
Technical Report 70-TEC-l, Analytical Quality Control Service,
Bureau of Radiological Health (1970).
31
-------
APPENDIX. STATISTICAL CALCULATIONS
To illustrate the computations performed by the computer, example
calculations are given using data for three actual samples analyzed at
one laboratory (Laboratory D).
The experimental data are listed and the mean, range, and the
experimental sigma are computed. These statistics provide measures of
the central tendency and dispersion of the data.
The normalized range is computed by first finding the mean range,
R, the control limit, CL, and the standard error of the range, aD.
K
The normalized range measures the dispersion of the data (precision)
in such a form that control charts may be used. Control charts allow
one to readily compare past analytical performance with present per-
formance. In the example, the normalized range equals 0.3 R which
falls inside the upper warning level, R + 2oR. The precision of the
results is acceptable.
The normalized ^deviation is calculated by computing the deviation
and the standard error of the mean, a. The normalized deviation
allows one to readily measure central tendency (accuracy) through the
use of control charts. Trends in analytical accuracy can be determined
in this manner. For this example, the normalized deviation is -0.7
which falls within the upper and lower warning levels. The accuracy of
the data is acceptable.
Finally, the experimental error of all laboratories, the grand
average, and the normalized deviation from the grand average are cal-
culated in order to ascertain the performance of all the laboratories
as a group. Any bias in methodology or instrumentation may be found
from these results.
32
-------
EXAMPLE CALCULATIONS (Laboratory D Data)
Experimental data:
Known value = y = 3273 pCi 3H/liter urine on September 24, 1974
Expected laboratory precision = a = 357 pCi /liter
Laboratory Samp! e Result
D Xi 3060 pCi/liter
D x2 3060 pCi /liter
D x3 3240 pCi /liter
Mean = x
N
x = - = T- = 312° PCi /liter
M j
where N = number of results
Range = r
r = [maximum result - minimum result)
= | 3240 - 3060 | = 180 pCi /liter
Experimental sigma = s
N - 1
- V
3060)' + (3060)^ + (3240)^ - (3060 + 3060 + 3240)^
= 103.9 pCi/liter
33
-------
Normalized range = wR + xaR
Mean range = R
R = d2a where d2 = 1.693 for N = 3*
= (1.693)(357)
= 604.4 pCi/liter
Control limit = CL
CL = R + 3aR
= DuR where D* = 2.575 for N = 3*
= (2.575)(604.4)
= 1556 pCi/liter
Standard error of the range = OD
K
aR = 1/3 (R + 3aR - R)
= 1/3 (D*R - R)
= 1/3 (1556 - 604.4)
= 317.2 pCi/liter
wR + xaR = 1R + XCTR
1R
r - wR
°R
on for r > R
* Rosensteln, M., and A. S. Goldin, Statistical Techniques for Quality
Control of Environmental Radioassay, AQCS Report Stat-1, U.S. Depart-
ment of Health, Education and Welfare, PHS, November 1964.
34
-------
wR + xaR = wR + oaR
wR
Frl R for r < R
LRj
OTT
since 18° < 604-4
= 0.30 R
Normalized deviation of the mean from the known value = ND
Deviation of mean from the known value = D
D = x - y
= 3120 - 3273
= - 153 pCi /liter
Standard error of the mean = a
ND = _
am
_ - 153
" 2S57T
= - 0.7
= 357
= 206.1 pCi/liter
35
-------
Experimental sigma (all laboratories) = st
= 149 pCi/liter
Grand average = GA
N
N
49345
= 3290 pCi/liter
Normalized deviation from the grand average = ND1
Deviation of the mean from the grand average = D'
D1 = x - GA
= 3120 - 3290
= - 170 pCi/liter
ND' = .
am
- - 170
20FT
= - 0.8
36
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-680/4-75-007
3. RECIPIENT'S ACCESSIOWNO.
4. TITLE AND SUBTITLE
Preliminary Milk Report
5. REPORT DATE
June 1975
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Arthur N. Jarvis and David G. Easterly
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORG \NIZATION NAME AND ADDRESS
Technical Support Laboratory
National Environmental Research Center
P. 0. Box 15027
Las. Vegas, Nevada 89114
10. PROGRAM ELEMENT NO.
1HA327
11. CONTRACT/GRANT NO.
In-house report
12. SPONSORING AGENCY NAME AND ADDRESS
Office of Research and Development
U.S. Environmental Protection Agency
Washington, D.C. 20460
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A summary of the results of the milk cross-check program from July 1973 through
November 1974 is given. Examination of these results reveals that 29% of the
participants were within the plus or minus 3 sigma control limits for strontium-89
analysis, 42% for the strontium-90, 52% for barium-140, 60% for iodine-131, and
77% for cesium-137. These results indicate the need for improvement in analytical
procedures for the radionuclides studies. Accurate analysis of strontium-89 was
particularly difficult for most laboratories to achieve, while the accurate
analysis of cesium-137 was the least difficult.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. cos AT I Field/Group
milk analysis
isotopes 89Sr, 90Sr,
quality control
quantitative analysis
laboratory performance
131I, 13?Cs
i sotopes
quality assurance
radioactivity
radiochemistry
07 05
12 02
14 07
18 02, 04, 08
18. DISTRIBUTION STATEMENT
Release unlimited
19. SECURITY CLASS (This Report)
unclassified
21. NO. OF PAGES
40
20. SECURITY CLASS (Thispage>
unclassified
22. PRICE
EPA Form 2220-1 (9-73)
GPO 693-
i-740/4
'60
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