Short name:
CIMS

Full name:
Chemical Ionization Mass Spectrometer with CF3O-

What is being measured:
Gas-Phase Compounds

Sampling Protocol:
Online

Manufacturer:
Varian

Model:
1200 triple quadrupole mass analyzer

Instrument year :
None specified

Data recording software:

Data analysis software:
matlab

Raw data time resolution:
162 to 172 s

Analysis data averaging:
signal for the compound is normalized to the 86 signal

Detection limit:
ppb

Sensitivity to temperature (and correction method, if applicable): :

Sensitivity to relative humidity (and correction method, if applicable): :
Must account for the water signals

Sampling method:

Sample preparation method:

Sample residence time (chamber to instrument) (seconds):

Length of tubing (cm):

Instrument flow rate:

Tubing inner diameter:

Tubing material:

Chemical identification method:
In this analysis, benzyl alcohol concentration comes from the 193 scan

Data analysis method:
To get the concentration of benzyl alcohol in ppb, one takes the 193 signal at a given time and divides by the 86 signal (interpolated to that exact time) and then uses that signal to compare to the calibrated ppb/normalized signal value

Quantification method:

Calibration method:
The 193 m/z signal (the mass of benzyl alcohol + CF3O-), which was measured every 162 to 172 s, was normalized to the 86 m/z signal (the M+1 peak for CF3O-) and used to measure the benzyl alcohol concentration. This signal was calibrated using dilutions of a 800 L Teflon bag of ~44 ppb benzyl alcohol. The concentration in this bag was verified using fourier transform infrared absorption (FT-IR) spectroscopy with a 19 cm pathlength and absorption cross sections from the Pacific Northwest National Laboratory (PNNL) database. In this way, any wall or sampling loss was accounted for since the CIMS sampled from the same volume as the FT-IR. Multiple FT-IR samples were taken until they gave the same concentration; this was to ensure a minimal effect from any compound deposited on the instrument walls.

Calibration drift estimate:

Calibration schedule:

Uncertainty estimation method:
During the background collection period of ~1 h for each experiment, the standard deviation of the benzyl alcohol mixing ratio along with the uncertainty in the calibration was used to estimate the uncertainty of the initial benzyl alcohol mixing ratio. This combined standard deviation was also used as the uncertainty in the measurement of the time-resolved gas-phase mixing ratios throughout the experiment. Since the number that matters for the SOA yield is the reacted benzyl alcohol, which is the measured benzyl alcohol subtracted from the initial benzyl alcohol, the variance of the reacted benzyl alcohol is the sum of the variances of the initial and measured benzyl alcohol mixing ratios. The uncertainty reported is, then, the square root of the reacted benzyl alcohol mixing ratio variance.

Known interferences:

Link to supplemental information:

Additional notes:

Measurement uncertainty:
For benzyl alcohol, this is given in the third column

Measurement units:
ppb (otherwise, just signal)