Quantitative dermination of hydrogen sulfide in gases, e.g. for monitoring waste gases, using flow system with biosensor comprising sulfur-oxidizing bacteria immobilized on oxygen sensor and/or pH sensor

摘要

Selective quantitative determination of hydrogen sulfide (H2S) in a gas phase is carried out in a flow system using a biosensor comprising living chemolithoautotropic sulfur-oxidizing bacteria immobilized on an oxygen sensor and/or a pH sensor, over which oxygen-containing buffer solution flows. An analyte-enriched absorbent is injected cyclically into the flow, such that biochemical reaction with the microorganisms causes variation (to be detected and evaluated) in the oxygen utilization and/or pH value of the buffer solution. Independent claims are included for: (A) a method for controlled transfer of analytes (A) (preferably H2S) from a gas phase into a liquid phase for measuring purposes, involving supplying the (A)-containing gaseous sample through a gas channel (7) within a diffusion module (6), such that (A) permeates a semipermeable membrane (8) and enters an absorbent (16) flowing (in cocurrent or countercurrent) in a liquid channel (9) at the opposite side of the membrane, so that the resultant (A) concentration in the absorbent is adjustable to a measurable region of the measurement device by variation of the volume flow of the absorbent pump (14), on the basis of varying material exchange in the diffusion module; and (B) apparatus for selective quantitative determination of H2S in a gas phase, comprising: (a) an automated flow system with a sensor capsule (1) containing immobilized microorganisms (as above) (2), close to a signal generator (3) and linked to a control, evaluation and display unit (5); (b) a diffusion module (6) for controlled transfer of the analyte (i.e. H2S) from a gas phase into a liquid absorbent (16), connected to an injection unit (10) so that at least one (preferably two) sample loop(s) (12) is/are fillable within the injection unit; and (c) an injection unit (10) for injection of H2S-containing absorbent into flowing buffer solution (17), linked with the sensor capsule such that the buffer solution flows over the immobilized microorganisms.