Instrument - High-Resolution Aerosol Mass Spectrometer
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