2 methoxy 4 methylphenol

Diethyl ether, dansyl chloride, and saturated
alkane standards were purchased from Sigma-Aldrich (Gillingham, Dorset,
UK). O-(2,3,4,5,6-Pentafluorobenzyl)-hydroxylamine
hydrochloride (PFBHA) was purchased from Fluka (Loughborough, UK).
The following food-grade aroma compounds were purchased from Sigma-Aldrich
(purity in parenthesis): acetaldehyde (≥99%), acetic acid (≥99.5%),
2,3-butanedione (97%), butanoic acid (≥99%), (E)-β-damascenone (≥98%), dimethyl sulfide (≥99%),
5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone (97%),
5(or 2)-ethyl-4-hydroxy-2(or 5)-methyl-3(2H)-furanone
(96%), (Z)-4-heptenal (≥98%), 3-hydroxy-4,5-dimethyl-2(5H)-furanone (10% in propylene glycol), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (≥98%), methional (≥97%), 2-methoxy-4-methylphenol
(≥98%), 2-methoxyphenol (≥99%), 2-methoxy-4-vinylphenol
(≥98%), 2-methylbutanal (≥95%), 3-methylbutanal (≥97%),
3-methylbutanoic acid (99%), 3-methyl-1-butanol (≥98%), methylpropanal
(≥98%), 2,3-pentanedione (≥96%), phenylacetaldehyde
(10% in ethanol), 2-phenylacetic acid (≥99%), 2-phenylethanol
(≥99%), vanillin (≥97%), and 4-vinylphenol (10% in propylene
glycol). Encapsulated 3-methyl-2-butene-1-thiol flavor standard (0.02–4
ng/g) was purchased from FlavorActiV (Aston Rowant, UK).

Methyleugenol (4-allyl-1,2-dimethoxybenzene);
eugenol (4-allyl-2-methoxyphenol); 3,4-dimethoxytoluene; 2-methoxy-4-methylphenol;
3,4-dimethoxyphenol; cerium(IV) sulfate; sulfuric acid; DTPA; hemoglobin;
and HRP (Type VI) were purchased from Sigma-Aldrich (St. Louis, MO).
Reagents were generally of the highest purity available and were used
as received. The buffer for those reactions using it was 50 mM, pH
7.4, phosphate buffer prepared by diluting a 500 mM solution treated
with Chelex 100 resin (Bio-Rad, Hercules, CA) to remove adventitious
transition metal ions. These solutions also contained either 1.0 mM
or 0.1 mM DTPA to further hinder trace metal catalysis. The H₂O₂ concentration was confirmed by absorbance measurements
at 240 nm (ε₂₄₀ = 39.4 M^–1 cm^–1).^{40 (link)} In some experiments,
the commercial preparation of HRP was loaded onto a PD-10 gel filtration
column and eluted with 50 mM phosphate buffer, pH 7.4, treated with
chelex before use. This was done primarily to remove reducing impurities
from the sample. The concentration of HRP was determined from the
Soret maximum at 412 nm (ε_native HRP = 102 mM^–1 cm^–1).^{41 (link)}