Short name:
CARMA SMPS

Full name:
Soft X-ray Differential Mobility Analyzer in Negative Mode

What is being measured:
particle number, area, volume, mass concentration

Sampling Protocol:
Online

Manufacturer:
Custom

Model:
Custom

Instrument year :
Until Spring of 2019

Data recording software:
NI DAQ with Labview

Data analysis software:
Inversion in Matlab

Raw data time resolution:
0.5 Seconds

Analysis data averaging:
330 Seconds

Detection limit:
10nm-1um

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

Sensitivity to relative humidity (and correction method, if applicable): :
Low up to 40%, if humidity is too high, connect a dryer tube before the inlet, and correct the size based on reduced humidity

Sampling method:
Direct Sampling

Sample preparation method:

Sample residence time (chamber to instrument) (seconds):
13

Length of tubing (cm):
80

Instrument flow rate:
0.5 lpm

Tubing inner diameter:
1/4 inch

Tubing material:
Stainless Steel

Chemical identification method:

Data analysis method:
Data analysis is carried through data inversion based on finite element analysis of particle trajectories along the DMA column, Monte Carlo simulation of particle Brownian motion, and CPC RTD modeling described in Mai et al (I & II, 2018). The custom build Matlab software takes in the raw output from the instrument, and inverts it to particle size distribution.

Quantification method:

Calibration method:
Flow calibration is performed by fitting pressure transducer response current and flow measure from Gilibrator directly. Voltage calibration is performed by fitting HV source loop feedback current and multimeter measurement. Peaks are adjusted by sampling PSL (50nm, 150nm, 300nm, 500nm) directly into the instrument.

Calibration drift estimate:
Low (on the order of weeks)

Calibration schedule:
As Needed

Uncertainty estimation method:
The uncertainty of data acquisition is low, and the uncertainty of data analysis mainly lies to the larger end of a size distribution. The uncertainty is estimated by comparing the original tail and adjusted tail (fitting normal distribution)

Known interferences:

Link to supplemental information:
https://www.tandfonline.com/doi/abs/10.1080/02786826.2018.1528005 https://www.tandfonline.com/doi/abs/10.1080/02786826.2018.1528006

Additional notes:

Measurement uncertainty:
10%

Measurement units:
particle number (#/cm3), particle area (um2/m3), particle volume (um3/m3), SOA mass (ug/m3)