PM2.5 Chemical Speciation

U.S. Environmental Protection Agency (EPA) standards for air quality include provisions for particulate matter (PM) with aerodynamic diameters smaller than 2.5 microns (PM2.5). The deployment of a PM2.5 monitoring network is a critical component in the national implementation of these standards. We have extensive experience and capabilities in assisting the nation's particle monitoring networks.

The RTI Difference

As the national leader for PM2.5 chemical speciation studies, RTI was selected as EPA's sole contractor for the chemical speciation of PM2.5 filter sample analysis for the nationwide network of monitoring sites. We are one of only a few labs in the U.S. that can perform this service. Our laboratory facilities and instrumentation meet or exceed the very stringent Federal Reference Method (FRM) requirements for PM2.5 analysis. Our gravimetry laboratory and staff have been featured in EPA training videos for the national compliance (mass) and chemical speciation programs for PM2.5.

We understand the challenges associated with supporting a continuously operating network of samplers. Our staff specialize in coordinating with field operators and data handlers to maintain a set sampling schedule, while protecting sample integrity during shipment and data integrity during analysis.


In support of states, tribal councils, and commercial consulting and engineering firms, we offer chemical speciation of 2.5 particles and related gases, gravimetric analysis, and quality assurance services.

Chemical Speciation

  • Site selection for PM2.5 monitoring
  • Installation and calibration of speciation samplers
  • Data management and analysis: data entry, database management, data analysis and interpretation
  • Turnkey laboratory services
    • Preparation and shipment of speciation sampler components (filter cassettes, filter packs, denuders, absorbents)
    • Extraction and analysis of major ions by ion chromatography
    • Carbon analysis by thermal/optical carbon analyzer (total, elemental, organic, carbonate)
    • X-ray fluorescence spectroscopy for elements Al through Pb
    • Analytical services for toxic substances and semivolatile compounds in PM2.5
    • Denuder refurbishment and analysis

Gravimetric Analysis

  • Filter preparation, shipping, and weighing
  • Data compilation, data validation, and data entry to the EPA Air Quality System
  • Skills and equipment training in the client lab, the RTI lab, or the field
  • Filter and filter/cassette evaluations for moisture pickup, alkalinity, and surface imperfections
  • Single-particle characterization by X-ray diffraction and light or electron microscopy

Environmental Scanning Electron Microscopy

  • High resolution
  • Elemental analysis and particle imaging
  • Differentiation and relative abundance of particle types

Quality Assurance and Training

  • Training in quality assurance and the operation and maintenance of commercially available speciation and FRM samplers
  • Independent review of networks, including third-party systems and performance reviews, collocated sampler studies, and field system audits
  • Preparation and review of documents such as quality assurance project plans and standard operating procedures for FRM and speciation sampler networks