Thermal Desorption Sample Introduction Instruments

Importance of Thermal Desorption in Analytical Chemistry

Thermal desorption is a critical sample introduction technique for gas chromatography that uses heat, rather than solvents, to extract organic compounds from solid or air samples. It provides high sensitivity, minimal sample handling, and eliminates solvent interference, making it indispensable in environmental monitoring, industrial hygiene, homeland security, and product emissions testing.

Objectives and Study Overview

This document presents an overview of CDS Analytical’s Dynatherm thermal desorption instruments. The aim is to illustrate their design features, performance capabilities, and application scope in high-precision trace analysis.

Methodology

Thermal desorption is performed in two sequential steps. First, volatile and semi-volatile analytes are trapped on a primary sorbent tube during sample collection. In the second step, the analytes are rapidly released by heating the tube and refocused on a smaller bore trap for narrow-band injection into a gas chromatograph. This cryogen-free process ensures high injection efficiency and minimizes water interference by purging moisture prior to desorption.

Used Instrumentation

Key instruments covered include:

• 9300 Series single-tube thermal desorber
• 9305 near-real-time sampler with mass flow control and vacuum pump
• 9350 continuous dual-tube real-time monitoring system
• 7500 and 7500S autosamplers with 72-position trays and optional internal standard addition
• Associated accessories: sorbent tube conditioners, multi-channel air samplers, focus traps

Key Findings and Discussion

Dynatherm systems span a broad analyte range (C2–C33+), covering polar and nonpolar, halogenated and nonhalogenated compounds at concentrations from sub-ppt to percent levels. Heating rates up to 1000°C/min for sample tubes and 900°C/min for traps enable rapid cycle times. Electronic controls and software interfaces allow method storage, leak checking, timed events, and integration with major GC platforms. The dual-stage trapping approach achieves efficient analyte capture and release without cryogenic cooling.

Practical Benefits and Applications

Advantages of this thermal desorption approach include high throughput, minimal solvent use, and automated operation. Common applications are:

• Ambient and indoor air toxics monitoring
• Stack and fugitive emissions analysis
• Soil gas and vapor intrusion studies
• Chemical warfare agent detection and demilitarization support
• Product emissions testing for carpets, fragrances, and food packaging
• Occupational hygiene assessments

Future Trends and Opportunities

Ongoing developments may include integration of thermal desorbers with mass spectrometry for enhanced compound identification, further miniaturization for field-deployable systems, and advanced automation with AI-driven method optimization. Expansion into real-time continuous monitoring and remote networked operation will further broaden application areas.

Conclusion

CDS Analytical’s Dynatherm thermal desorption platforms deliver robust, cryogen-free, high-sensitivity sample introduction for a wide range of volatile and semi-volatile compounds. Their modular design, coupled with advanced software control, supports diverse analytical challenges in environmental, industrial, and security sectors.

Reference

CDS Analytical LLC 2017 product literature.