Met One SASS & SuperSASS: PM2.5 Chemical Speciation Samplers

High-Fidelity Chemical Speciation for Regulatory Compliance & Air Quality Research

The Met One SASS (Speciation Air Sampling System) and SuperSASS are the established industry standards for the collection of PM2.5 samples for detailed chemical analysis. Engineered specifically for the rigorous demands of the EPA Chemical Speciation Network (CSN), these systems allow environmental agencies and researchers to capture particulate matter with exceptional integrity. Unlike standard gravimetric samplers, the SASS series is designed to preserve volatile chemical species—such as nitrates and organic carbon compounds—that are often lost due to temperature fluctuations or contamination during field handling.

Available in two configurations—the 5-channel SASS and the 8-channel SuperSASS—this platform offers the flexibility required for both routine regulatory monitoring and complex source apportionment studies. By utilizing individual, laboratory-sealed "sampling canisters," the system virtually eliminates field contamination, ensuring that the data returned from the laboratory reflects the true atmospheric composition.

Key Benefits

• Advanced Sample Integrity: Both models feature a specialized convective solar radiation shield that actively maintains sample cassette temperatures within 5°C of ambient air. This prevents the volatilization of temperature-sensitive semi-volatile compounds (SVCs) like ammonium nitrate and organic aerosols.

• Contamination-Free Workflow: The modular "Canister" design integrates the PM2.5 Sharp Cut Cyclone (SCC), denuders, and filter cassettes into a single unit. These canisters are prepared and sealed in the cleanroom environment of the laboratory, transported to the field, and returned without the operator ever touching the filters or inlet surfaces.

• Regulatory Compliance: Designed to meet and exceed U.S. EPA requirements for chemical speciation, these samplers are field-proven in major monitoring networks, including the EPA Speciation Trends Network and California Air Resources Board (CARB) sites.

• Flexible Multi-Channel Sampling:

  • SASS: Up to 5 simultaneous sampling channels for comprehensive single-event analysis.

  • SuperSASS: Up to 8 channels with sequential programming, allowing for multi-day sampling events or expanded chemical arrays without site visits.

Technical Overview

The SASS and SuperSASS systems are built around a philosophy of modular sampling. Each channel operates independently with its own volumetric flow control, typically set to 6.7 LPM—the optimal flow rate for the integrated Sharp Cut Cyclone (SCC) to achieve a precise PM2.5 cut-point.

The Canister Concept

The heart of the system is the Sampling Canister. Each canister houses:

1. Inlet: A dedicated PM2.5 size-selective inlet (SCC).

2. Denuder (Optional): To remove interfering gases (e.g., nitric acid, ammonia) before they reach the filter, preventing positive artifacts.

3. Filter Media: Supports various configurations including Teflon, Nylon, and Quartz filters, arranged in single or tandem packs.

Active Flow Control

The SuperSASS improves upon the original design by incorporating four independent volumetric flow controllers. This allows for complex sequencing (e.g., "Sample Group A" on Day 1, "Sample Group B" on Day 3) or simultaneous sampling with different flow requirements, all managed via an intuitive electronic interface.

Typical Use Cases

• Source Apportionment Studies: Collecting filter samples to analyze trace metals (XRF), ions (IC), and elemental/organic carbon (TOR/TOT) to determine if pollution originates from diesel traffic, biomass burning, or industrial smelters.

• National Speciation Networks: Deployed by government agencies to track long-term trends in hazardous air pollutants (HAPs) and secondary aerosol formation.

• Health Effect Research: Providing precise chemical data to link specific aerosol components (e.g., heavy metals vs. sulfates) to respiratory or cardiovascular health outcomes.

• Remote/Unmanned Monitoring: The SuperSASS's multi-day sequential capability makes it ideal for remote sites where daily operator access is impractical.

Why Choose This Sampler?

The Met One SASS series solves the "volatile loss" problem that plagues standard FRM samplers. If your monitoring objective goes beyond simple mass concentration to understanding what the pollution is made of, sample preservation is non-negotiable. The SASS/SuperSASS design ensures that the semi-volatile fraction of PM2.5—often a significant portion of the total mass—is retained on the filter rather than evaporating. Combined with the elimination of field cleaning (since the entire canister is swapped), it reduces operator error and guarantees laboratory-grade data quality in the field.

Specifications

• Measured Components:

  PM2.5 Chemical Speciation (including Trace Metals, Sulfate, Nitrate, Ammonium, Elemental Carbon, Organic Carbon, and Semi-Volatile Organic Compounds).

• Applications:

  EPA Chemical Speciation Networks (CSN), Source Apportionment, Atmospheric Chemistry Research, Secondary Aerosol Studies.

• Certifications:

  Exceeds U.S. EPA Speciation Sampler requirements; Field-verified by CARB and EPA testing programs.

• Measurement Principle:

  Multi-channel Gravimetric and Chemical Filter Sampling (Active Volumetric Flow Control with Denuder/Filter Pack configurations).