Research Article

A Statistical Estimation Approach for Quantitative Concentrations of Compounds Lacking Authentic Standards/Surrogates Based on Linear Correlations between Directly Measured Detector Responses and Carbon Number of Different Functional Groups

Table 5

Comparison of percent difference (PD) between the actual and projected response factor (RF) values for all ( ) or three chemical groups ( ) in relation to three major variables of reference VOCs used for prediction: carbon number, molecular weight, and boiling point.

OrderVariablesFunctional groupNumber of chemicalsPDaPredictive equationb P value
MeanSDSlopeIntercept

1 Carbon numberAll compoundsc18 17.9 19.0 34,175 −82,472 0.9396
2 Aldehyde4 9.83 6.55 24,836 −60,290 0.9725
3 Aromatic6 2.03 0.76 29,456 −43,139 0.9713
4 Carboxylic4 12.7 4.30 29,818 −58,701 0.9012

Mean0.9462 0.0162
 SD      0.0336 0.0239

5 Molecular weightAll compounds18 40.6 27.4 2,784 −145,760 0.5445
6 Aldehyde4 9.79 6.49 1,773 −88,781 0.9726
7 Aromatic6 1.73 1.22 2,142 −33,879 0.9738
8 Carboxylic4 12.7 4.28 2,126 −126,763 0.9013

Mean0.8481 0.0163
 SD      0.2052 0.0238

9 Boiling pointAll compounds18 81.5 112 609 31,947 0.1404
10 Aldehyde4 16.2 10.0 961 −30,600 0.8870
11 Aromatic6 2.08 0.89 949 58,007 0.9687
12 Carboxylic4 17.7 7.19 1,358 −158,432 0.7813

Mean0.6944
 SD      0.3772

Percent difference (PD) = /RF(actual) * 100.
bThe predictive equations are derived from linear regression analysis between the number of carbon (x-axis) and actual RF values (y-axis).
cAA is not considered.