radiello allows the sampling of presumed air concentration levels of a large number of airborne compounds, present both in the gaseous state and as vapours.
By choosing an appropriate sampling time, depending on the presumed air concentration levels, it is possible sampling presumed air concentration levels both at high concentrations (typically in a working environment) and at low concentrations (typically in an urban or indoor environment).
The sources of pollution can be the most varied: in an industrial environment they depend on work and production activities, in an urban environment they mainly consist of vehicle traffic, the use of domestic heating or the presence of nearby production facilities. Finally, in indoor environments, the sources of pollution are mainly furniture and furnishings, cigarette smoke, household hygiene products, food preparation and outdoor air, if you are in a highly urbanized area.
Finally, in indoor environments, the sources of pollution are mainly furniture and furnishings, cigarette smoke, household hygiene products, food preparation and outdoor air, if you are in a highly urbanized area. With the diffusive radiello sampling system it is possible sampling presumed air concentration levels of numerous categories of substances, listed below, with a brief description of the samplers and specific accessories for each type of compound and the recommended analytical techniques. The complete list of compounds and the details of the analytical techniques with which it is possible to measure sampling presumed air concentration levels of airbone pollutants is shown in the pages of the specific sampling methods.
Volatile Organic Compounds (VOCs)
Sampling presumed air concentration levels of Volatile Organic Compounds or VOCs (aliphatic, aromatic, chlorinated hydrocarbons, alcohols, esters, ketones, etc.) can be carried out with two types of radiello® diffusive samplers with radial symmetry:
The radiello diffusive sampler for VOCs with chemical desorption, which contains the adsorbing cartridge code 130: it consists of a stainless steel mesh tube (100 mesh), 60 mm long and 5.8 mm in diameter, filled with 530 ± 30 mg of active carbon 35-50 mesh; the cartridge is inserted in the white diffusive body (standard type); the VOCs are captured by adsorption, are deadsorbed with a suitable solvent (carbon sulfide) and are analyzed by capillary gas chromatography with flame ionization detector (HRGC-FID). The chemical desorption sampler, thanks to the high adsorbing capacity of the cartridge code 130, is recommended for sampling in the workplace, even with high concentrations, and for sampling of one or two weeks in urban air, for medium or high concentrations.
The radiello VOC sampler with thermal desorption, which contains the adsorbing cartridge code 145: it consists of a 60 mm long, 4.8 mm diameter, narrow mesh (3×8 µm aperture) stainless steel mesh tube filled with 350±10 mg of 35-50 mesh graphite carbon (Carbograph 4); the cartridge is inserted into the yellow diffusive body (high thickness); the VOCs are captured by adsorption, recovered by thermal desorption and analyzd by capillary gas chromatography with a FID or MS detector (HRGC-FID or HRGC-MS). The thermal desorption sampler, thanks to the great sensitivity offered by this technique, applied to the cartridge code 145, is recommended for sampling of low concentrations in ambient air or indoor air, for sampling of one or two weeks, and for sampling of low concentrations in non-industrial work environments.
In particular, with both techniques, the following classes of compounds can be sampled:
Aliphatic hydrocarbons (hexane to dodecane)
Aromatic hydrocarbons (benzene, toluene, ethylbenzene, xylenes or BTEX, trimethylbenzene, styrene)
More details on all compounds that can be sampled with one or the other technique, depending on the chemical affinity of the two adsorbents, are available on the specific pages.
The radiello system for sampling presumed air concentration levels for aldehyde sampler contains the chemiadsorbent cartridge code 165, consisting of a stainless steel mesh tube (100 mesh), 60 mm long and 5.8 mm in diameter, filled with FlorisilTM coated with 2.4-dinitrophenylhydrazine (2.4-DNPH). The cartridge is inserted in the blue diffusive body (photoprotective). The aldehydes react with the 2,4-DNPH to give the corresponding 2,4-dinitrophenylhydrazone. The 2,4-dinitrophenylhydrazones are extracted with acetonitrile and analyzed by reversed-phase HPLC with a UV detector. The following aldehydes can be sampled: formaldehyde, acetaldehyde, acrolein, benzaldehyde, propanal, butanal, isopentanal, pentanal, hexanal, glutaraldehyde.
Phenol, methylphenols and dimethylphenols dispersed in air are determined with the radiello diffusive sampler, containing the adsorbing cartridge code 147, containing a stainless steel mesh tube (100 mesh), 60 mm long and 4.8 mm in diameter, filled with Tenax TA; the cartridge is inserted in the white diffusive body (standard type); the analysis is performed by thermal desorption, followed by capillary gas chromatography, with mass spectrometry detection (ATD-HRGC-MS).
The following isomers of methylphenol are determined individually: 2-methylphenol (o-cresol), 3-methylphenol (m-cresol), 4-methylphenol (p-cresol); the following isomers of dimethylphenol are also determined: 2,3-dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol.
The radiello system for sampling presumed air concentration levels for 1,3-butadiene and isoprene contains the cartridge code 141, consisting of a stainless steel net tube with a narrow mesh (opening 3×8 µm), 60 mm long and 4,8 mm in diameter, filled with about 350 mg of graphite carbon (Carbopack X). To distinguish it from the cartridge code 145, which has a similar appearance and size, the cartridge code 141 bears the “Carbopack X” mark on the outer surface of the steel mesh; the cartridge is inserted into the yellow diffusive body (high thickness). The analysis is performed by thermal desorption, followed by capillary gas chromatography, with mass spectrometric detection (ATD-HRGC-MS). With this sampler 1,3-butadiene and isoprene can be determined.
The radiello sampler for hydrogen sulphide contains the code chemiadsorbent cartridge, consisting of an inert support, of microporous material, 60 mm long and 5.8 mm in diameter, impregnated with zinc acetate; aa cartridge is inserted in the white diffusive body (standard type). The reaction with hydrogen sulphide in the air produces zinc sulphide which is stable. The reaction with N,N-dimethyl-p-phenylenediammonium in a strongly acid solution and in the presence of ferric chloride as an oxidant produces the blue dye of methylene, which is determined by spectrophotometry. This sampler is specific for the determination of hydrogen sulphide.
The Radiello system for sampling presumed air concentration levels for hydrochloric acid contains the cartridge code 169, consisting of a stainless steel mesh tube (100 mesh), 60 mm long and 5.8 mm in diameter, filled with silica gel 0.1-0.4 mm; the cartridge is inserted into the white diffusive body (standard type). The gaseous hydrochloric acid is adsorbed by the silica gel, from which it is recovered with water and dosed by ion chromatography as chloride ion. The uptake is selective for hydrochloric acid: its salts, possibly present in the air as aerosols, are not able to cross the diffusive wall of radiello.
The radiello sampler for hydrofluoric acid contains the chemiadsorbent cartridge code 166, consisting of an inert support, made of microporous material, 60 mm long and 5.8 mm in diameter, impregnated with moist triethanolamine (TEA); the cartridge is inserted in the blue diffusive body (photoprotective). The gaseous hydrofluoric acid is adsorbed by the TEA, is recovered with water and dosed as fluoride ion in ion chromatography.
The radiello system for sampling presumed air concentration levels for ammonia contains the chemiadsorbent cartridge code 168, consisting of a hollow cylinder of microporous inert material, 60 mm long and 5.8 mm in diameter, impregnated with phosphoric acid; the cartridge is inserted in the blue diffusive body (photoprotective). Ammonia is absorbed in the form of ammonium ion. The ammonium salts dispersed in air in the form of corpuscles are not able to pass through the diffusive wall of radiello.
The ammonium ion is colorimetrically determined: in an alkaline environment, the ammonium ion reacts with phenol and sodium hypochlorite, under the catalytic action of pentacyanonitrosilferrate, to form indophenol, intensely colored in blue. This sampler is specific for the determination of ammonia.
The radiello ozone
sampler contains the chemiadsorbent cartridge code 172, consisting of a hollow
cylinder of inert microporous material, 60 mm long and 5.8 mm in diameter,
filled with silica gel coated with 4.4′-dipyridylethylene and closed at one end
by a PTFE cap; the cartridge is inserted in the blue diffusive body
(photoprotective). During exposure, ozonolysis of 4,4′-dipyridylethylene in an
acid environment leads to 4-pyridylaldehyde.
In the laboratory,
4-pyridylaldehyde is condensed with 3-methyl-2-benzothiazolinone hydrazone
(MBTH) to produce the corresponding azide, yellow coloured. The indirect
determination of ozone is then performed by spectrophotometry.
The radiello system for sampling presumed air concentration levels for nitrogen dioxide (NO2) and sulphur dioxide (SO2) contains the chemiadsorbent cartridge code 166, consisting of an inert support, of microporous material, 60 mm long and 5.8 mm in diameter, impregnated with moist triethanolamine (TEA); the cartridge is inserted in the blue diffusive body (photoprotective). Nitrogen dioxide (NO2) and sulphur dioxide (SO2) are adsorbed by the TEA respectively in the form of nitrite and sulphite ions, which are easily oxidised to sulphate ions. The nitrite ion can be measured by spectrophotometry in the visible; all ions (nitrite, sulphite and sulphate) can be determined by ion chromatography. In addition to nitrogen dioxide and sulphur dioxide, this sampler can also be used for the determination of hydrofluoric acid, formic acid and acetic acid. The latter are adsorbed by the TEA in the form of ions (formate and acetate respectively), which can also be determined by ion chromatography.
The radiello system for sampling presumed air concentration levels for anaesthetic gases and vapours contains the cartridge code 132 consisting of a stainless steel mesh tube (100 mesh), 60 mm long and 5.8 mm in diameter, filled with a mixture of molecular sieve and active carbon 35-50 mesh; the cartridge is inserted into the diffusive body with a silicone membrane (poorly permeable to water vapour).
Nitrous oxide and
halogenated anesthetics permeate the silicone membrane and are captured by the
molecular sieve and activated carbon respectively. The analytes are desorbed with a
water-methanol mixture and analyzed by headspace injection and capillary gas
chromatography coupled with mass spectrometry (required for the detection of
sevorane and desflurane). This sampler can be used for the determination of
nitrous oxide, forane, sevorane, desflurane.
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