CDS 7350 Automated Liquid Purge and Trap Concentrator

Overview

The CDS 7350 Automated Liquid Purge and Trap Concentrator is a high-reliability, fully automated sample preparation system engineered for the quantitative enrichment of volatile organic compounds (VOCs) from aqueous matrices prior to gas chromatographic analysis. It operates on the fundamental principle of dynamic headspace extraction: a controlled stream of inert carrier gas (typically helium or nitrogen) purges VOCs from a heated aqueous sample; the evolved analytes are then selectively trapped on a sorbent-packed concentrator tube at ambient temperature. Subsequent thermal desorption transfers the enriched analytes quantitatively into the GC or GC–MS inlet. Unlike cryogenic trapping systems, the 7350 employs room-temperature capture — eliminating liquid nitrogen or mechanical refrigeration — thereby reducing operational complexity, moisture co-elution risk, and methanol carryover often associated with cold-trap condensation. This architecture supports robust, long-term unattended operation in regulated environmental, drinking water, and wastewater laboratories.

Key Features

• Ambient-temperature trap technology: Eliminates cryogens and avoids ice/methanol formation, ensuring consistent trap efficiency and minimizing baseline artifacts.
• Integrated optical foam sensor: Detects foam generation during purge in real time, automatically halting purge and initiating rinse to prevent cross-contamination and system blockage.
• Precision 2 µL internal standard delivery: Fixed-volume quantitative loop ensures repeatable spiking accuracy critical for EPA Method 524.4, 624.1, and ISO 15681 compliance.
• 72-position autosampler tray: Enables true high-throughput batch processing without manual intervention — ideal for large-volume regulatory monitoring programs.
• Flow-path-isolated moisture removal: Dedicated water trap positioned upstream of the concentrator tube; desiccant-based removal occurs independently of the analytical desorption path, preserving peak shape and sensitivity for polar VOCs (e.g., vinyl chloride, chloroform, benzene).
• Ultra-inert fluidic pathway: Entire sample and transfer path — from vial to trap to GC interface — uses SilcoNert®-passivated stainless steel and fused-silica components, preventing adsorptive losses of reactive or low-concentration analytes (e.g., acrolein, epichlorohydrin).

Sample Compatibility & Compliance

The CDS 7350 is validated for use with potable water, surface water, groundwater, wastewater, and leachate per U.S. EPA Methods 502.2, 524.2, 524.4, and 624.1. Its design conforms to key requirements for GLP and GMP environments: full audit trail capability via CDS AutoControl™ software (including user login, method versioning, run log timestamps, and parameter change history), electronic signature support aligned with FDA 21 CFR Part 11, and traceable calibration verification logs. The absence of cryogenic hardware simplifies facility qualification (IQ/OQ/PQ) and reduces maintenance-related downtime.

Software & Data Management

CDS AutoControl™ v5.x provides intuitive method development, sequence scheduling, real-time status monitoring, and integrated diagnostics. All instrument parameters — purge time, trap desorption profile, bake-out cycles, internal standard timing, and moisture trap saturation alerts — are programmable and stored with digital signatures. Raw method files and run reports export in CSV and PDF formats compatible with LIMS integration. Audit trails are encrypted and tamper-evident; data retention policies align with ISO/IEC 17025 documentation requirements.

Applications

Primary applications include regulatory compliance testing for trihalomethanes (THMs), haloacetic acids (HAAs) precursors, BTEX (benzene, toluene, ethylbenzene, xylenes), chlorinated solvents (e.g., PCE, TCE), and emerging contaminants such as 1,4-dioxane. The system is routinely deployed in EPA-certified environmental labs, municipal water quality divisions, and contract testing facilities performing multi-analyte VOC panels under state and federal mandates. Its compatibility with both single-quadrupole and triple-quadrupole GC–MS platforms enables confirmatory analysis and low-level quantitation down to sub-ppt levels in complex aqueous backgrounds.

FAQ

Does the CDS 7350 require liquid nitrogen or mechanical cooling?

No — it utilizes ambient-temperature sorbent trapping, eliminating cryogen dependency and associated safety and logistical constraints.
Can it be interfaced with non-CDS gas chromatographs?

Yes — it features a universal GC interface with standardized 1/16″ OD stainless-steel transfer line and Swagelok®-compatible fittings, supporting all major GC and GC–MS vendors.
How does the system handle foaming samples such as wastewater or detergent-laden effluents?

An optical foam sensor detects bubble formation in real time and triggers automatic purge termination and vial rinsing to prevent carryover and maintain system integrity.
Is moisture management validated for high-humidity samples?

Yes — the isolated, inline water trap achieves >95% water removal efficiency while preserving VOC recovery; performance is verified per EPA Method 524.4 Appendix B protocols.
What regulatory documentation is provided for installation qualification?

CDS supplies comprehensive IQ/OQ documentation packages, including factory calibration certificates, material certifications for inert components, and traceable test reports against ASTM D5059 and ISO 15681-2 specifications.