An open platform for Aerosol InfraRed Spectroscopy analysis – AIRSpec
<p>AIRSpec is a platform consisting of several chemometric packages developed for analysis of Fourier transform infrared (FTIR) spectra of atmospheric aerosols. The packages are accessible through a browser-based interface, which also generates the necessary input files based on user interacti...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-04-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://www.atmos-meas-tech.net/12/2313/2019/amt-12-2313-2019.pdf |
| Summary: | <p>AIRSpec is a platform consisting of several chemometric packages developed
for analysis of Fourier transform infrared (FTIR) spectra of atmospheric
aerosols. The packages are accessible through a browser-based interface,
which also generates the necessary input files based on user interactions for
provenance management and subsequent use with a command-line interface. The
current implementation includes the task of baseline correction, organic
functional group (FG) analysis, and multivariate calibration for any analyte
with absorption in the mid-infrared. The baseline correction package uses
smoothing splines to correct the drift of the baseline of ambient aerosol
spectra given the variability in both environmental mixture composition and
substrates. The FG analysis is performed by fitting individual Gaussian line
shapes for alcohol (aCOH), carboxylic acid (COOH), alkane (aCH), carbonyl (CO),
primary amine (<span class="inline-formula">aNH<sub>2</sub></span>), and ammonium (ammNH) for each spectrum.
The multivariate calibration model uses the
spectra to estimate the concentration of relevant target variables (e.g.,
organic or elemental carbon) measured with different reference instruments.
In each of these analyses, AIRSpec receives spectra and user choices on
parameters for model computation; input files with parameters that can later
be used with a command-line interface for batch computation are returned
together with diagnostic figures and tables in text format. AIRSpec is built
using the open-source software consisting of R and Shiny and is released
under the GNU Public License v3. Users can download, modify, and extend the
package, or access its functionality through the web application
(<span class="uri">http://airspec.epfl.ch</span>, last access: 3 April 2019) hosted at the École polytechnique
fédérale de Lausanne (EPFL). AIRSpec provides a unified framework by
which different chemometric techniques can be shared and accessed, and its
underlying suite of packages provides the basic functionality for extending
the platform with new types of analyses. For example, basic functionality
includes operations for populating and accessing spectra residing in
in-memory arrays or relational databases, input and output of spectra and
results of computation, and user interface development. Moreover, AIRSpec
facilitates the exploratory work, can be used by FTIR spectra acquired with
different methods, and can be extended easily with new chemometric packages
when they become available. Therefore AIRSpec provides a framework for
centralizing and disseminating such algorithms. This paper describes the
modular architecture and provides examples of the implemented packages using
the spectra of aerosol samples collected on PM<span class="inline-formula"><sub>2.5</sub></span> polytetrafluoroethylene (Teflon) filters.</p> |
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| ISSN: | 1867-1381 1867-8548 |