Chemistry Reference
In-Depth Information
Table 1.
Seven elasticity classes obtained by binning samples with similar elasti-
city at 3 = 6.5 mN m
-1
Elasticity Class
Class ID
1
2
3
4
5
6
7
Bin elasticity
range
(mN m
-1
)
6.1
-7.7
8.5
-9.4
9.6
-10.6
11.2-
13.5
14.7
-15.6
24.5
-26.1
21.2
# Samples in
class *
18
12
15
21
9
3
12
Mean elasti-
city for class
(mN m
-1
)
7.2
±0.7
8.9
±0.3
10.3
±0.4
12.2
±0.9
15.2
±0.5
25.6
±0.8
21.2
Mean D1
Score for class
-0.097 -0.063 -0.056 -0.013
+
0.040
+
0.199 +0.222
Std. deviation of
D1 score
for class
±
0.001
±
0.019
±
0.006
±
0.007
±
0.007 n. a.
±0.003
*Individual mass spectrum/elasticity pairs
3. Results and Discussion
The Chemometricks analysis developed discriminant functions that distin-
guished each sample or sample class from every other based on the princi-
pal mass components of the spectra. Applied to individual spectra, the dis-
criminant functions yielded a function score that reflected the abundance
of those chemical components in the sample mixture that distinguished the
sample or class from the others. Experimentally measured static elasticities
for the samples were then compared with the discriminant scores to deter-
mine the degree of correlation between the spectral patterns and surface
elasticity.
In Figures 1-3, we present the results of the LDA analysis of the 30 F1
surfactant extracts for the case where classes were defined by binned elas-
ticity. Trends were roughly similar whether the spectral classes were de-
fined by replicates or by binned elasticity value. The Chemometricks algo-
rithm was not given any information about the elasticity values other than
which samples exhibited similar elasticities at a fixed surface pressure, yet
