Acrichi AGS-72 Automated Non-Methane Hydrocarbons (NMHC) Gas Sampler

Overview

The Acrichi AGS-72 is a fully automated, benchtop gas sampling and injection system engineered for precise, high-reproducibility introduction of non-methane hydrocarbon (NMHC) gas samples into gas chromatographs (GC). It operates on a quantitative loop injection principle—where a fixed volume of sample gas is captured in an inert, temperature-stable loop prior to pressurized transfer into the GC inlet—ensuring stoichiometric accuracy and minimal carryover. Unlike syringe-based or pressure-balanced gas injectors, the AGS-72 eliminates manual intervention, flow-dependent variability, and adsorption losses by integrating electropneumatic valve sequencing, passivated stainless-steel fluidic pathways, and programmable reverse-purge needle cleaning. Designed for compliance with EPA Method 25A, ISO 11890-2, and ASTM D6667 for NMHC speciation, it supports both discrete laboratory analysis and continuous process monitoring when interfaced with industrial GC systems.

Key Features

• 72-position sample carousel with barcode-compatible vial recognition (optional)
• Quantitative loop injection architecture with customizable loop volumes (standard 1 mL; optional 0.5–5 mL)
• Sub-0.3 mm robotic positioning repeatability ensures consistent loop filling and transfer timing
• Electro-pneumatically actuated, chemically inert valves (electropolished 316L SS + PTFE seals) for long-term stability under humid or corrosive gas matrices
• Integrated corrosion-resistant sampling pump capable of zero-pressure and slight negative-pressure (< −20 kPa) extraction from stack ducts, canisters, or Tedlar bags
• Onboard reverse-purge cleaning cycle for injection needle and loop after each analysis—prevents cross-contamination without solvent use
• Modular pneumatic interface compatible with standard GC carrier gas supplies (He, N₂, H₂) and auxiliary purge lines

Sample Compatibility & Compliance

The AGS-72 accommodates gaseous samples stored in 6–12 mL evacuated glass or aluminum canisters, stainless-steel passivated cylinders, and flexible gas-tight bags (e.g., FlexFoil®, Tedlar®). Its fluidic path is constructed entirely from sulfur-passivated stainless steel and perfluoroelastomer (FFKM) seals, minimizing catalytic degradation of reactive NMHC species (e.g., isoprene, terpenes, aldehydes). The system meets hardware-level requirements for GLP-compliant operation: all motion commands, valve actuations, and timing events are timestamped and logged locally. When paired with validated software (see Software & Data Management), it supports audit trails compliant with FDA 21 CFR Part 11 for regulated environmental laboratories.

Software & Data Management

The AGS-72 is controlled via Acrichi GC-Sampler Suite—a Windows-based application supporting method-driven scheduling, multi-level user authentication, and real-time status monitoring. Users define custom sequences including sample dwell time, loop pressurization duration, injection delay, and number of replicate injections per vial. All operational parameters—including valve timing logs, motor encoder feedback, and pressure transducer readings—are archived in a relational SQLite database with SHA-256 hash integrity verification. Export options include CSV, PDF analytical reports, and direct integration with LIMS via ODBC drivers. Remote diagnostics and firmware updates are supported over Ethernet (TCP/IP), enabling centralized fleet management across distributed monitoring sites.

Applications

• Regulatory NMHC monitoring per EPA Method 25A and Chinese HJ 38-2017 in ambient air, landfill gas, and combustion exhaust
• Industrial hygiene screening for volatile organic compounds (VOCs) in workplace atmospheres
• Calibration gas delivery for GC-FID, GC-PID, and GC-MS systems requiring trace-level hydrocarbon standards
• Long-term unattended operation in fenceline monitoring networks with scheduled 24/7 sampling cycles
• Method development for speciated hydrocarbon analysis where loop-based reproducibility outperforms thermal desorption or direct injection approaches

FAQ

Can the AGS-72 be integrated with third-party gas chromatographs without hardware modification?
Yes—the system uses standardized pneumatic interfaces (¼” Swagelok fittings) and TTL-level trigger signals compatible with Agilent, Thermo Fisher, Shimadzu, and PerkinElmer GC models.
Is the 1 mL quantitative loop volume fixed, or can it be changed during routine operation?
Loop volume is hardware-defined; however, Acrichi offers factory-swappable loop modules (0.5 mL, 1 mL, 2 mL, and 5 mL) with recalibrated valve timing profiles—no field tools required.
How does the reverse-purge cleaning cycle prevent memory effects between high-concentration and low-concentration samples?
Each cycle delivers ≥3× the internal volume of the needle and loop with carrier gas at 150 kPa, followed by a 5-second dwell under vacuum—validated to reduce residual methane signal to <0.2% of previous injection peak area.
Does the AGS-72 support dynamic headspace or thermal desorption modes?
No—it is optimized exclusively for direct gas-phase injection via quantitative loop. For solid-phase or liquid-phase matrices, Acrichi recommends coupling with its HS-72 headspace sampler or TD-20 thermal desorber.
What environmental certifications does the instrument hold?
CE marking (EMC Directive 2014/30/EU and Low Voltage Directive 2014/35/EU); RoHS 2011/65/EU compliant; conforms to IEC 61000-4-2/3/4 for industrial electromagnetic environments.