Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N1/00—Sampling; Preparing specimens for investigation
  • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
  • G01N1/40—Concentrating samples
  • G01N1/405—Concentrating samples by adsorption or absorption
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
  • G01N31/22—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators
  • G01N31/223—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators for investigating presence of specific gases or aerosols
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
  • G01N33/98—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving alcohol, e.g. ethanol in breath
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N1/00—Sampling; Preparing specimens for investigation
  • G01N1/02—Devices for withdrawing samples
  • G01N1/22—Devices for withdrawing samples in the gaseous state
  • G01N1/2202—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling
  • G01N1/2214—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling by sorption

Definitions

• the invention relates to the detection of low molecular weight compoundsr especially ethanol andmethanol/ in the presence of highermolecularweight compounds and is particularly but not exclusively related to a methanol detector for atmosphere monitoring in closed environments.
• Methanol (CH30H) is a toxicsubstanceandwhenpresentinclosedenvironments thereisaneedtoroutinelymonitortheair. Amoni ormustbeableto signal that the ambient level of methanol is less than a maximum permissible concentration.
• a commercially availableDraeger detector tube Methanol 50/a
• Methanol 50/a can be used tomonitor methanol in the range 50 to 3000 ppm.
• Other tubes are available for themonitoringof other compounds.
• the detector itself consists of a narrow bore tube containing a precleansing layer of drying agent followed by crystals impregnated with an orange Chromium (Cr(VI)) compound.
• Cr(VI) Chromium
• a sample of air of standard volume is drawn through the detector tube by means of a bellows pump.
• the presence of methanol in that sample causes a colour change in the tube fromorange to black.
• Thelength of theblack stain thendetermines the amount of methanol present in the sample for the given volume of air.
• the detection process is illustrated by:
• An object of the present invention is to provide a means to detect low molecular weight compounds when present in a sample with higher molecular weightcontaminants.
• Afurtherobjectofthepresentinventionisto provide ameanstomonitormethanol inthepresenceofnoctane.
• Ayetfurtherobject is to provide a means to detect ethanol in the presence of other organic species.
• the invention provides a detector for monitoring low molecular weight compounds in the presence of higher molecular weight species comprising: a porous adsorber having relatively low retention for the low molecular weight co ⁇ pounds and relatively high retention for highermolecularweight species; and a reagent which undergoes a colour change on reaction with low molecular weight compounds; the arrangement being such that the adsorber and reagent are contained such that a sampleofair canbepassedthroughtheadsorberbeforepassingthrough the reagent, th amount of low molecular weight compound being calculable from the amount of reagent which changes colour.
• lowmolecularweightcompound canbe referingtoeitherorganicor inorganic compounds.
• the low molecular weight compounds are organic Compounds.
• theorganiccompounds areeithermethanol or ethanol.
• the lowmolecularweightcompound isanorganiccompound itpreferably contains between1 and5 carbonatomsandmaybe straightchainoroptionally branched.
• the compounds may also be substituted. Typical groups of compounds would be Cj to C5 alkanes, alkenes, amines, alcohols, aldehydes, ketones organo-halides, such as vinyl chloride, etc.
• SUBSTITUTE SHEET molecular weight compound is inorganic it will preferably comprise 2 to 4 atoms and typical examples could includeNCfc, S02, C02, NO, CO etc.
• Higher molecularweight compounds referstocompoundscontainingmore than5 atoms. Thesevalues are thosewhichare generally applicable to theporous adsorber Tenax andwhere other adsorbers are used thetypesofcompoundsand retention on the adsorber on the basis ofmolecularweightmayvary.
• the reagent isas specificaspossibletothecompoundsorclasses of compounds which require detection.
• the reagent is a Chromium (VI) compound which changes colour from orange to black on reaction with methanol or ethanol.
• the Chromium (VT) compound is impregnated on crystalscontainedwithinatubewithwiregauzesbeingprovidedtoretainthe crystals.
• a drying agent may also be included in the tube to removewater from the air sample before passing over the reagent.
• the adsorber is a porous powdered polymer, poly 2,6 diphe ⁇ l-p-phe ⁇ ylene oxide which may be retained by glass wool plugs.
• the adsorber may be contained withinthesametubeasthereagentorinasecondtubewhichisconnectableto thereagenttube. Inapreferredarrangementthereagentandadsorbermaybe sealed before air sairpling and a pumpmeans is provided to draw a standard volume of air sample through the detector.
• the reagent tube 10 available from Draeger, is a narrow-bore tube partly filled with orange Chromium (VI) compound 12, retained by plugs 13 ofwire.
• VI Chromium
• SUBSTITUTE SHEET show that Tenax selectively removes the n octane, thereby removing amajor cross sensitivity problem when detecting methanol.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Immunology (AREA)
• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Pathology (AREA)
• General Physics & Mathematics (AREA)
• General Health & Medical Sciences (AREA)
• Biochemistry (AREA)
• Analytical Chemistry (AREA)
• Molecular Biology (AREA)
• Urology & Nephrology (AREA)
• Hematology (AREA)
• Biomedical Technology (AREA)
• Medicinal Chemistry (AREA)
• Food Science & Technology (AREA)
• Microbiology (AREA)
• Cell Biology (AREA)
• Biotechnology (AREA)
• Dispersion Chemistry (AREA)
• Biophysics (AREA)
• Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)

Applications Claiming Priority (6)

Publications (1)

Family

ID=27264566

Family Applications (1)

Country Status (2)

Families Citing this family (7)

Family Cites Families (3)

• 1990
  • 1990-07-04 EP EP19900910797 patent/EP0485410A1/de not_active Withdrawn
  • 1990-07-04 WO PCT/GB1990/001029 patent/WO1991001001A1/en not_active Ceased

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events