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Application Notes – Technical support

Application Note 001: Uptake rates for tube-type axial diffusive samplers
This Application Note provides a listing of uptake rates for tube-type axial diffusive samplers, for a range of commonly used sorbents. Values are provided for hydrocarbons, halogenated compounds, esters, glycol ethers, ketones, aldehydes and alcohols, while separate lists are given for a few key compounds for exposure periods typical of workplace (8-hour) and environmental (24-hour to 4-week) monitoring scenarios.
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Application Note 002: Prediction of uptake rates for diffusive tubes
This Application Note describes the theory and practice of predicting the uptake rate for a particular analyte–sorbent combination when using diffusive (passive) samplers. This can help analysts to overcome the limitation of having to experimentally determine uptake rates for every analyte–sorbent combination of interest.
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Application Note 005: Advice on sorbent selection, tube conditioning, tube storage and air sampling
This Application Note gives advice on which sorbents to use for pumped or diffusive (passive) tube monitoring of various vapour-phase organics, and suggests optimum criteria for conditioning and storing packed tubes.
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Application Note 006: Troubleshooting analytical thermal desorption applications
This Application Note describes some of the most commonly encountered technical issues relating to the use of thermal desorption systems, and advises on how to solve them. Points covered include poor peak shape, chromatogram artefacts, carryover and poor recovery of analytes, poor peak precision, cold trap cooling problems, leak test failures, and problems relating to the presence of air and/or water.
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Application Note 007: Calibration: Preparing and introducing thermal desorption standards using sorbent tubes
This Application Note describes the theory and practice of using standards to calibrate thermal desorption systems. Guidance on the operation of Markes’ Calibration Solution Loading Rig™, use of internal standards, and methods for quality assurance and calibration are included.
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Application Note 008: The theory and practice of diffusive monitoring
This Application Note describes the theory and practice of using axial and radial samplers for diffusive (passive) monitoring of organic volatiles in air. Advice is given on how to calculate atmospheric concentrations from the weight of analyte on-tube, and criteria for successful sampling.
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Application Note 010: Use of diffusive samplers with TD–GC analysis for monitoring VOCs in ambient air
This Application Note reviews indoor and outdoor air monitoring of volatile organic compounds (VOCs) using tube-type diffusive samplers and thermal desorption (TD)–GC analysis. Specific attention is paid to general sampling/analytical procedures, concentration/detection limits, applicable analyte ranges, minimising artefacts, quality assurance and method limitations.
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Application Note 019: Minimising artefacts: Considerations for storage and transport of sorbent tubes
This Application Note describes the practical aspects of tube handling, capping and uncapping, short- and long-term tube storage, tube conditioning, and preparation of laboratory blanks.
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Application Note 020: Confirming sorbent tube retention volumes and checking for analyte breakthrough
This Application Note describes a simple procedure for checking analyte breakthrough prior to or during field monitoring, using pairs of tubes linked together in series. This guidance also complies with recommendations in standard thermal desorption methods for air monitoring.
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Application Note 021: Developing and optimising TD methods
This Application Note describes pre-desorption checks of thermal desorption (TD) systems, selecting and validating optimum TD conditions, and criteria for method performance.
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Application Note 022: Selection of gas flows and split ratios during thermal desorption
This Application Note describes how to select minimum and maximum gas flows, and how to calculate split ratios when optimising thermal desorption methods.
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Application Note 025: Calculating atmospheric concentrations from analyte masses retained on sorbent tubes
This Application Note describes how to calculate atmospheric concentrations from the analyte masses retained on sorbent tubes, for pumped and diffusive monitoring.
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Application Note 026: Minimising analytical interference from water during the analysis of sorbent tubes
This Application Note describes the four basic approaches to eliminating interference from water when monitoring air using sorbent tubes – minimising the volume of air sampled, the appropriate selection of sorbents, sample splitting, and the selective elimination of water.
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Application Note 030: Certified reference materials for analysis of VOCs in air by TD–GC
This Application Note describes the use of certified reference standards and methods to estimate analytical bias in thermal desorption (TD)–GC analyses.
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Application Note 038: Occupational exposure limit levels for VOCs compatible with TD–GC
This Application Note tabulates those chemicals with ‘standard’ occupational exposure limits at or below 10 ppm that are compatible with analysis by thermal desorption (TD)–GC. It also provides information on sorbents, sampling methods and safe sampling volumes (SSVs).
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Application Note 042: Uptake rates for radial diffusive samplers
This Application Note lists uptake rates for 22 representative airborne pollutants onto radial-type Radiello® diffusive samplers, with Carbograph™ 4TD sorbent cartridges and a sampling time of 7 days.
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Application Note 055: Using the FLEC to determine emissions of VOCs from materials and products
This Application Note describes the principles behind use of the Field & Laboratory Emission Cell (FLEC®) for material emissions testing according to standard methods.
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Application Note 075: Liquid standard injection, tube impedance and other factors that may cause discrimination during the calibration of TD methods
This Application Note describes the issues that may arise as a result of differences between samples and calibrants for thermal desorption (TD), and the operating conditions under which these effects may be significant. Guidance for minimising the impact of such differences (and for validating that a given method is not subject to these effects) is also presented, together with advice on routine monitoring of tube impedance.
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UK
UK
Markes International Ltd
Gwaun Elai Medi-Science Campus
Llantrisant
RCT
CF72 8XL, UK
Tel: +44 (0)1443 230935
Germany
Germany
Markes International GmbH
Schleussnerstrasse 42
D-63263 Neu-Isenburg
Frankfurt
Germany
Tel: +49 (0)6102 8825569
USA (West)
USA
Markes International, Inc
2355 Gold Meadow Way
Gold River
California 95670
USA
Tel: 866-483-5684 (toll-free)
Part of Schauenburg International
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