Comparison of methods for determination of desorption efficiencies

Abstract

Three methods for desorption efficiencey determination were compared with a reference dynamic method for 12 compounds. Only one of them gave values that were statistically different. The method, in which standard solutions of determined compounds in CS2 are injected onto charcoal, is recommended to all laboratories dealing with air analysis as it is simpler than the dynamic method. Independence of the desorption efficiency on charcoal loading was also confirmed. The desorption efficiences for individual compounds and their mixtures were found to be different.

Rapid determination of desorption efficiency, and analysis of solvent mixtures for occupational exposure studies

“…The DE is influenced by factors such as air humidity, collection flow rate, the amount of vapors collected, the desorption liquid, and the volume used, and by the composition of the solvent mixture being collected and analyzed [3,7,9,12,14]. DE is influenced by the mixture characteristics in two ways.…”

“…This method requires determination of, and control over, air humidity, temperature, atmospheric pressure, gas concentrations, and homogeneity, and independent means of testing are required for confirmation. The high cost of instrumentation, training, and labor, and the extended period of time necessary for the preparation of the standardized atmospheres, have motivated proposals for more accessible alternatives [7,9].…”

“…Determination of the DE is an important step in analysis, and it is necessary perform this step for each examination, because of the possibility of variation between lots of adsorbent material, or for other reasons, e. g. the composition of the chemical mixture collected [7,8].…”

Sampling and sample preparation of environmental material

“…Krajewski 97) compared three methods of determining desorption efficiencies to dynamically prepared standards and found the phase equilibrium data somewhat higher in most cases. Evans and Horstman ,00) also showed that the recovery of styrene from dynamically sampled tubes was 18 ~ lower than the direct spike method.…”

Occupational exposure to rubber vulcanization products during repair of rubber conveyor belts in a brown coal mine

“…This method of determination of desorption efficiencies is routinely used in our laboratory as yielding results closest to that of the dynamic method. 12 Examples of desorption of the determined compounds are given in Table 3. The desorption coefficients of the analyzed Efficiencies of extraction of separate PAHs from glass fibre filters did not have to be determined since the calibration was carried out on glass fibre filters treated exactly as the collected air samples.…”