MS calibration
curves for nitroglycerin and diphenylamine were collected every day
that had sample measurement following methods described previously.21 (link) Briefly, a length of 1/4-inch (outer diameter)
sulfinert stainless-steel tube (5 inches in length) was packed with
200 mg of deactivated glass wool (Restek; Bellefonte, PA). Several
milligrams of nitroglycerin (1 mg/mL in acetonitrile; Sigma-Aldrich;
Burlington, MA) or diphenylamine (≥99%; Sigma-Aldrich; Burlington,
MA) were deposited into the packed tubes using standard solutions,
and the solvents were dried at least overnight by passing N2 through the tube (50 mL/min). Once dried, sequential flow rates
of N2 were passed through the saturator tube into the ionization
source to create calibration curves.
For data processing, background
and sample intensities were separately averaged per sample measurement.
The background intensity was then subtracted from the sample intensity,
and the difference was calibrated to vapor concentration. Concentrations
from all monitored transitions were averaged together. For measurements
of GSRs over time, the concentration for a time point was reported
only if all transitions responded above the limit of quantitation
(LOQ; signal to noise over 10).
curves for nitroglycerin and diphenylamine were collected every day
that had sample measurement following methods described previously.21 (link) Briefly, a length of 1/4-inch (outer diameter)
sulfinert stainless-steel tube (5 inches in length) was packed with
200 mg of deactivated glass wool (Restek; Bellefonte, PA). Several
milligrams of nitroglycerin (1 mg/mL in acetonitrile; Sigma-Aldrich;
Burlington, MA) or diphenylamine (≥99%; Sigma-Aldrich; Burlington,
MA) were deposited into the packed tubes using standard solutions,
and the solvents were dried at least overnight by passing N2 through the tube (50 mL/min). Once dried, sequential flow rates
of N2 were passed through the saturator tube into the ionization
source to create calibration curves.
For data processing, background
and sample intensities were separately averaged per sample measurement.
The background intensity was then subtracted from the sample intensity,
and the difference was calibrated to vapor concentration. Concentrations
from all monitored transitions were averaged together. For measurements
of GSRs over time, the concentration for a time point was reported
only if all transitions responded above the limit of quantitation
(LOQ; signal to noise over 10).