ISO 16000-38:2019 pdf free.Indoor air – Determination of amines in indoor and test chamber air- Active sampling on samplers containing phosphoric acid impregnated filters.
4 Amines in indoor air
4.1 Properties of amines
Amines are basic and polar substances.
There are primary, secondary, tertiary, and quaternary amines.
Quaternary amines are not included in this document as they have no free electron pair and therefore have very different properties. In this document, the term “amines” includes primary, secondary, and tertiary amines only.
Not protonated a mines are oxidation sensitive.
The reaction of arnines with acids results in ammonium salts of the amines. The ammonium salts are
not oxidation sensitive.
4.2 Origin and occurrence of amines in indoor air
Amines are produced by technical chemical processes and processing and in addition by biotic or abiotic decomposition of nitrogen compounds. Besides sources of biological origin, indoor air sources ofamines could be, for instance, products containing polyurethane, especially foams, such as in vehicle seats, mattresses, pillows, and upholstered furniture or as thermal insulation or sound absorbing material. Several amines, in particular aromatic amines, are known as harmful compounds. Furthermore, most amines have an unacceptable odour in combination with a low odour threshold.
Further sources are for example food, such as fish (aliphatic amines) and cigarette smoke (aromatic amines).
5 Sampling strategy — Measurement procedure
5.1 Structure and properties of the samplers
The basic structure of an amine sampler for active sampling consists of a container, preferably a glass or plastic tube, and a filter. The filter is impregnated with an acid with low vapour pressure and without an oxidizing effect. In this regard, phosphoric acid is most suitable. The filter material itself shall be inert, such as untreated glass wool, glass spheres or glass frits. Basically, the inert filter material could be a porous, inert polymer. The suggested sampler consists of a glass tube with 6,25 mm outside diameter on a length of 60 mm, and a tapering on a length of 20mm with an outside diameter of the tip of 2,5 mm. The suggested filter consists of 50 mg of untreated glass wool impregnated with approximately 100 iirnol or 9,8 mg H3P04, respectively. The sampler that is described as an example in this document (see £2) is handmade. Until now, no verified commercially available amine samplers for active sampling are known.5.2.2 Implementation Approximately 100 ml acetonitrile are filled into a 200 ml volumetric flask. Then 470 iii phosphoric acid 85 % are filled into the flask and mixed with the acetonitrile. After that, the flask is filled up to the 200 ml mark with acetonitrile and the solution is mixed again to get a 34,3 mmol/l 113P04 solution in acetonitrile. 2,5 g glass wool is transferred into a 500 ml round bottom flask together with 200 ml 34,3 mrnol/l H3P04 solution in acetonitrile. (2,74 nmol H3P04/g glass wool). The acetonitrile is distilled off in a rotary evaporator at 100 r/inin and at a temperature of 90 °C to 100 °C. Each glass tube is packed with (50,0 ± 0,5) mg of the resulting impregnated glass wool (corresponds to 137 itmol H3P04/sampler if all H3P04 remains on the glass wool and if the acid is equally distributed). The impregnated glass wool is compressed thoroughly in the glass tube. Both opening of the glass tube are scaled by suitable plastic caps. Until application, the samplers are stored in the freezer at —36 °C.
5.2.3 Verification
The mass of phosphoric acid on each sampler (approximately 9,8 mg or 100 irnoI, respectively) is verified by titrating 5 samplers for each batch (10 % of the batch) with a 0,01 molar aqueous solution of sodium hydroxide and phenolphthalein as an indicator. The change of colour corresponds to the second equivalence point (complies with approximately 20 ml 0,01 M NaOH solution).ISO 16000-38 pdf download.