Diazomethane, used for derivatization of phenolic compounds, was prepared from N-methyl-N-nitroso-p-toluenesulfonamide (Dielsald) (24) obtained from Sigma-Aldrich (Steinheim, Germany).
The partitioned phenolic compounds were acidified and back extracted with hexanes, dried over sodium sulfate, and derivatized with
diazomethane. We generated
diazomethane as needed from nitrosomethylurea precursor, as described elsewhere (28).
We converted the free acid to the methyl ester by adding 0.01-0.02 mL ethereal
diazomethane (previously diluted 1:10 with MTBE).
The internal standard (IS) 2,6-D was added at the same level as the SRS; the extract was then adjusted to 1 mL with 5% methanol in methyl-t-butyl ether and then methylated with
diazomethane (8,11).
These metabolites were measured by GC/EC after methylation with
diazomethane and micro-extraction of the esters from the reaction mixture using methyl tertiary butyl ether (MTBE).
Diazomethane was prepared from N-methyl-N-nitroso-P-toluene-sulfonamide (Diazald) obtained from Sigma-Aldrich (Steinheim, Germany) (20).
Those methods that derivatize using methylating agents such as
diazomethane cannot obtain an accurate analysis of DMP because endogenous inorganic phosphate produces the same trimethyl derivative.
Five drops of methanol were added, and the phenolic compounds were derivatized with
diazomethane in diethyl ether (0.5 mL).
Diazomethane was synthesized as described by Furniss et al.
Diazomethane was prepared by reacting N-nitroso-N-methylurea with concentrated KOH solution in ether (Kelm et al.
Phenolic compounds in the sample extracts and calibration standards were methylated by adding 1 mL
diazomethane. We synthesized
diazomethane in hexane by using N-nitroso-N-methylurea (Sigma-Aldrich, St.
The preparation and reactions of
diazomethane. Aldrichimica Acta 16:3-10.