Short name:
HR-AMS

Full name:
High-Resolution Aerosol Mass Spectrometer

What is being measured:
Submicron non-refractory aerosol OA, nitrate, sulfate, ammonium, chloride species mass concentrations. O/C and H/C elemental ratios. Positive matrix factorization sometimes applied to separate OA into source factor time series and mass spectra.

Sampling Protocol:
Online

Manufacturer:
Aerodyne Research, Inc

Model:
HToF

Instrument year :
2007

Data recording software:
Aerodyne AMS DAQ v4.11 to 5.0.8.12

Data analysis software:
Latest Squirrel/Pika analysis package in Igor. http://cires1.colorado.edu/jimenez-group/ToFAMSResources/ToFSoftware

Raw data time resolution:
10 s to 2 minutes for “GenAlt” and 1 Hz for “Fast MS”

Analysis data averaging:
None

Detection limit:
OA (22 ng/m3), sulfate (5 ng/m3), nitrate (3 ng/m3), ammonium (38 ng/m3), chloride (12 ng/m3) for 1-minute averages.

Sensitivity to temperature (and correction method, if applicable): :
little and not relevant to laboratory sampling

Sensitivity to relative humidity (and correction method, if applicable): :
None

Sampling method:
1-2 lpm pulled from chamber through ¼” OD Stainless Steel or copper tubing (3-6 m long) to instrument outside of temperature-controlled chamber enclosure. Dried with nafion drier during humid experiments. ~0.1 lpm sampled into instrument.

Sample preparation method:
None

Sample residence time (chamber to instrument) (seconds):
1

Length of tubing (cm):
600

Instrument flow rate:
1-2 lpm

Tubing inner diameter:
.16 in

Tubing material:
Stainless Steel

Chemical identification method:
NA

Data analysis method:
Squirrel/Pika analysis package in Igor. http://cires1.colorado.edu/jimenez-group/ToFAMSResources/ToFSoftware

Quantification method:
Standard Squirrel/Pika analysis methods. http://cires1.colorado.edu/jimenez-group/wiki/index.php/ToF-AMS_Main#Data_Analysis_Resources

Calibration method:
Overall sensitivity calibrated with monodisperse 300-400 nm dry ammonium nitrate particles size-selected with a DMA. Typically “event trigger” or “BFSP” method used while also running “MS mode” and “PToF mode”. Sometimes cross-checked with “CPC method”. Relative ionizations efficiencies (RIE) for ammonium and sulfate are calibrated with ammonium nitrate and ammonium sulfate particles (in “MS mode”). Particle time-of-flight (particle sizing) is calibrated with PSLs and size-selected ammonium nitrate for ~50-800 nm. See more details at: http://cires1.colorado.edu/jimenez-group/wiki/index.php/ToF-AMS_Main#Data_Analysis_Resources

Calibration drift estimate:
Medium (on the order of days)

Calibration schedule:
Every chamber experiment or every 3-5 days for intensive multi-day experiment series.

Uncertainty estimation method:
Bahrein et al. (JGR) 2009 (http://cires1.colorado.edu/jimenez/Papers/jgrd15378-sup-0003-txts01.pdf)l Xu et al. AS&T 2018 (https://www.tandfonline.com/doi/abs/10.1080/02786826.2018.1439570)

Known interferences:
NA

Link to supplemental information:
http://cires1.colorado.edu/jimenez-group/wiki/index.php/FAQ_for_AMS_Data_Users

Additional notes:
Mass concentration accuracies (2-sigma) of 38% for OA and 34% for inorganic species have been estimated for field measures with AMS. However, for pure compounds and laboratory-generated SOA, the sensitivity to organic compounds (relative ionization efficiency, RIE) may be substantially different from the standard applied RIE of 1.4, so uncertainties/biases may be much larger for OA if not constrained with additional knowledge of experiment-specific OA sensitives, comparisons to other measurements (e.g. SMPS, CPMA), etc. See for example Xu et al., 2018: https://www.tandfonline.com/doi/full/10.1080/02786826.2018.1439570

Measurement uncertainty:
Up to factor of 2 if not calibrated recently but more typically within. ~50%. If calibrated in last few days, typically within ~10%

Measurement units:
ug/m3