ACTRIS ACSM intercomparison – Part 1: Reproducibility of concentration and fragment results from 13 individual Quadrupole Aerosol Chemical Speciation Monitors (Q-ACSM) and consistency with co-located instruments

Abstract

Abstract. As part of the European ACTRIS project, the first large Quadrupole Aerosol Chemical Speciation Monitor (Q-ACSM) intercomparison study was conducted in the region of Paris for 3 weeks during the late-fall -early-winter period (November-December 2013). The first week was dedicated to the tuning and calibration of each instrument, whereas the second and third were dedicated to side-by-side comparison in ambient conditions with co-located instruments providing independent information on submicron aerosol optical, physical, and chemical properties. Near real-time measurements of the major chemical species (organic matter, sulfate, nitrate, ammonium, and chloride) in the non-refractory submicron aerosols (NR-PM 1 ) were obtained here from 13 Q-ACSM. The results show that these instruments can produce highly comparable and robust measurements of the NR-PM 1 total mass and its major components. Taking the median of the 13 Q-ACSM as a reference for this study, strong correlations (r 2 > 0.9) were observed systematically for each individual Q-ACSM across all chemical families except for chloride for which three Q-ACSMs showing weak correlations partly due to the very low concentrations during the study. Reproducibility expanded uncertainties of Q-ACSM concentration measurements were determined using appropriate methodologies defined by the International Standard Organization (ISO 17025, 1999) and were found to be 9, 15, 19, 28, and 36 % for NR-PM 1 , nitrate, organic matter, sulfate, and ammonium, respectively. However, discrepancies were observed in the relative concentrations of the constituent mass fragments for each chemical component. In particular, significant differences were observed for the organic fragment at mass-to-charge ratio 44, which is a key parameter describing the oxidation state of organic aerosol. Following this first major intercomparison exercise of a large number of Q-ACSMs, detailed intercomparison results are presented, along with a discussion of some recommendations about best calibration practices, standardized data processing, and data treatment.

Secondary organic aerosol from chlorine-initiated oxidation of isoprene

“…Low abundance has been cited as the reason for highly variable measurements of ambient particulate chlorine using ACSM and similar instruments (Crenn et al, 2015). Overall, our results indicate that the standard operating procedure of the ACSM and similar instrumentation may systematically underestimate particulate chlorine concentration.…”

“…The empirical correlations were derived using a comprehensive collection of aerosol mass spectrometer data sets but may underestimate O : C values for SOA formed under low-NO x conditions from isoprene or toluene . Variability in f 43 and f 44 among different ACSMs has also been reported (Crenn et al, 2015).…”

Chemical characterization and source apportionment of submicron aerosols measured in Senegal during the 2015 SHADOW campaign

“…It must be noted, however, that the uncertainties of mass concentrations with aerosol mass spectrometers are estimated at 20-35 % (2σ ) for the total mass (Bahreini et al, 2009). Furthermore, Crenn et al (2015) reported reproducibility-related uncertainties of Q-ACSM concentration measurements of 9, 15, 19, 28 and 36 % for NR PM 1 , nitrate, organic matter, sulfate and ammonium, respectively, during an intercomparison that involved 13 Q-ACSMs in the Paris area during springtime. In addition to the relative ion transmission efficiency correction applied using a naphthalene internal standard, the collection efficiency (CE) due to particle losses induced by an incomplete vaporization and/or transmission through the aerodynamic lens was also determined for the whole dataset.…”

Elemental composition of ambient aerosols measured with high temporal resolution using an online XRF spectrometer

“…The Q-ACSM determines quantitative mass spectra of nonrefractory (NR) particles up to mass to charge ratios (m/z) of 150 (Crenn et al, 2015;Ng et al, 2011). Ion fragments were attributed mainly to organic aerosols, nitrate, sulfate, ammonium, and chloride, which comprise the reported data used in this study.…”