Table 3. Statistical analysis of HMX (mg/kg) results from discrete and composite samples
taken from subgrid D2B for short-range spatial heterogeneity assessment.
Discrete samples
On-site colorimetric
HPLC (acetone)
Method 8330 (acetonitrile)
Sample
Mean
Mean
Mean
1
100 c
111 c
170 b
2
16 a
15.7 a
11.8 a
3
183 d
190 e
285 c
4
111 c
142 d
135 b
5
321 e
328 f
300 c
6
324 e
325 f
405 d
7
54 b
75.2 b
82 a,b
Mean
158
169
198
Numbers designated with the same letter within each column are not significantly different using the least
significant difference test at the 95% confidence level.
Discrete samples
ANOVA for on-site and lab analyses
On-site colorimetric
HPLC (acetone)
Method 8330 (acetonitrile)
F ratios
257*
478*
26.1*
Error MS
118.5
59.9
1453
Least sign. diff.
25.7
18.3
90.1
Analysis s (RSD) =
10.9 (6.9%)
7.7 (4.6%)
38.1 (19.2%)
Sampling s (RSD) =
123 (77.9%)
120 (71.4%)
135 (68.2%)
(s = standard deviation)
(RSD = relative standard deviation)
Linear correlation analysis for on-site colorimetric vs. lab HPLC (acetone) analysis
(r = correlation coefficient)
Slope
Intercept
r
Nonzero intercept
1.027
15.5
0.996
Zero intercept
0.963
0
Linear correlation analysis for on-site colorimetric vs. lab Method 8330 (acetonitrile) analysis (r = correlation
coefficient)
Slope
Intercept
r
Nonzero intercept
0.848
9.86
0.945
Zero intercept
0.813
0
Composite samples
On-site colorimetric
HPLC (acetone)
Method 8330 (acetonitrile)
n
3
3
2
Mean value
176
184
180
Standard deviation
12.8
5.19
84.9
RSD
7.3%
2.8%
47.1%
* Significant at the 99.9% level
respectively, indicating that homogenization of
using acetonitrile extraction and HPLC analysis
samples using simple, manual procedures was
(EPA Method 8330, EPA 1995). Statistical analysis
entirely adequate when 20-g subsamples were
is presented in Table 3.
used for analysis. The correlation coefficient (r)
Duplicate analyses conducted using the field
for on-site colorimetric and acetone HPLC results
colorimetric method and HPLC of the acetone
was 0.996, and the intercept of the linear model
extracts were quite precise and in excellent agree-
was not significantly different from zero. The slope
ment (Table 3). Mean values for individual
of the zero intercept linear regression relation-
samples varied from about 16 mg/kg to over 300
ship was 0.963, indicating that the two methods
mg/kg. RSDs for analysis were 6.9% and 4.6% for
gave essentially equivalent results.
the on-site colorimetric and acetone HPLC results,
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