Jean-Yves de Saint Laumer, Sabine Leocata, Emeline Tissot, Lucie Baroux, David M. Kampf,
Philippe Merle, Alain Boschung, Markus Seyfried, Alain Chaintreau
Our initial data set did not contain acetylenic compounds. However, we observed a systematic shift of about 33.4 kcal/mol for this functional class, in comparison with measured values reported in the literature, when the combustion enthalpies were predicted by Equation (7) . This shift has a significant impact only in the case of very small molecules. This bias rises to 13% for acetylene, the smallest possible acetylenic structure, and can be considered as the maximum error for this family of compounds. For compounds with four carbons such as 2-butyne, the bias decreases to 4.8%. Because our objective was to provide a very simple equation for the prediction of the flame ionization detector response factor, we did not introduce corrective parameters into our equations.
The robustness of the relative response factor (RRF) measurement was tested in a previous study
[1]
; however, the influence of the possible solvent had not been investigated.

As a test, we measured the purity of a series of fragrance allergens by using the predicted RRFs and the quick procedure (section 2.9.1). Four different solvents were used: dichloromethane, ethyl acetate, methyl pivalate, and toluene (Bp = 40, 77.1, 101, and 110.6 °C, respectively). The purities were consistent when the latter three solvents were used. However, when measured as a solution in the most volatile solvent, CH
2
Cl
2
, the purities were systematically overestimated because of an underestimation of the apparent RRFs. A very volatile solvent seems to give rise to injection selectivity.
Table S1 . Purities of commercial sources of fragrance allergens, and relative standard deviations
(RSDs) of purities over the different solvents.
Purities
 Products Solvent  EtOAc Toluene CH
2
Cl
2
Me Piv
Anisole
Limonene
Alpha Terpinolene
Linalool
4-Terpinen-1-ol
Geranial + Neral
(+)-R-8-methoxy-p-menthene
8-Methoxy-p-menthene
Linalyl Acetate
Hydroxy Citronellal
Gamma Damascone
Geranyl acetate
Coumarin
2E-Alpha Damascone a
2E-Alpha Damascone a
2E-Alpha Damascone a
102
87
99
106
106
98
102
84
50
107
91
99
105
116
105
108
108
92
110
112
115
105
106
86
51
108
96
96
102
113
106
110
102
88
100
106
110
99
102
84
50
106
90
99
105
115
105
108
101
85
96
105
102
95
100
84
50
96
90
99
104
111
105
107
RSD
All solvents
Without
CH
2
Cl
2
3.1%
3.3%
6.0%
3.0%
5.1%
4.2%
2.5%
1.2%
1.0%
5.3%
3.1%
1.5%
1.4%
1.9%
0.5%
1.2%
0.6%
1.8%
2.1%
0.5%
3.8%
2.1%
1.1%
0.0%
0.0%
5.9%
0.6%
0.0%
0.6%
2.3%
0.0%
0.5%

(E)-Beta Damascone b
(E)-Beta Damascone b
Methyl Isoeugenol o-Methoxy cinnamaldehyde
Methyl alpha ionone c
Methyl alpha ionone c
Propylidene Phthalide
Methyl Ionone (

+

+

)
Amylcinnamaldehyde
Farnesyl acetate
Geranyl benzoate
Median a, b, c Different batches.
98
99
87
100
76
89
88
78
89
90
85
98
105
90
105
81
94
98
81
95
92
81
106
110
98
124
87
101
108
88
106
105
96
99
102
89
105
79
92
94
80
93
88
81
3.9%
4.5%
5.3%
9.8%
5.8%
5.4%
8.7%
5.3%
7.6%
8.2%
8.3%
4.2%
The internal standard (ISTD) used to measure the experimental RRF values was an ester (methyl octanoate). Therefore, there was a risk of hydrolysis when it was added to the acidified biodegradation medium before extraction with CH
2
Cl
2
. To check its stability, we performed a blank experiment by using the biodegradation medium: the same amount of methyl octanoate was used as in a normal biodegradation experiment, plus an equal amount of tetralin as a second, nonhydrolyzable ISTD. The mixture was then extracted with CH
2
Cl
2
and the latter evaporated before dilution in ethyl acetate. The tetralin peak was used to quantify the remaining methyl octanoate, and its recovery was found to be 99.7%.
0.6%
2.9%
1.7%
2.8%
3.2%
2.7%
5.4%
1.9%
3.3%
2.2%
2.8%
1.9%
Resveratrol, malic and tartaric acids, and inositol, representing tri- to hexahydroxylated compounds, were derivatized with bis(trimethylsilyl)trifluoroacetamide/1% trimethylchlorosilane. The determination of their purities by using the quick procedure gave values between 90 and 108%. Whereas these values could fall within the variability of the RRF prediction, the lower calculated purity of tartaric acid and inositol could be inherent in a noncomplete derivatization, because it is known that steric hindrance can alter the silylation

yield. Thus, it is unlikely that the applicability of the algorithm to polysilylated products can be questioned by these results. In contrast, in the case of inositol, the hydroxyl groups were not hindered and a high predicted purity was observed.
Table S2 . Purity determination of polyhydroxylated compounds after silylation and by using the quick procedure (certified purities of underivatized compounds ≥ 99%).
Resveratrol-TMS
Malic acid-TMS
Tartaric acid-TMS
Inositol-TMS
TMS, trimethylsilyl.
OH
groups
4
6
3
3
Predicted
RRF
0.968
1.413
1.399
1.212
Apparent
RRF
0.897
1.532
1.557
1.350
Predicted
purity
108.0%
92.2%
89.9%
89.8%
[1] Cicchetti, E., Merle, P., Chaintreau, A. Flavour Fragrance J.
2008, 23, 450-459.