This method covers the following groups of components:
Chlororganic pesticides:
Polychlorinated biphenyls,
These components may be determined in air samples. The air samples can be collected with an air sampler with a particle filter followed by two PUF plugs. Filter and PUF plugs are extracted separately with a hexane/diethylether 9:1 mixture in a soxhlet extractor.
The extracts are concentrated and then cleaned by using adsorption chromatography (silica). After the concentration to the appropriate volume and addition of the recovery standard the components are separated and quantified by using gas chromatography combined with mass spectrometry (MS), see the chemical analysis chapter 4.19.
Materials and equipment of similar or better performance or quality from other manufacturers may be used.
NILU PUF (polyurethane
foam) sampler consists of a glass cylinder (10 cm i.d.) supplied with a
filter holder in one end. The other end is connected to a Siemens ELMO vacuum
pump2BH5 via an adapter and tube. The PUF sampling unit is outlined in Figure 3.13.1.
Figure
3.13.1: The
PUF sampling unit.
Inserting unexposed filter and PUF plugs and starting sampling:
Stopping sampling and removing exposed filter and PUF plugs:
Please note: All handling of PUF plugs must be with disposable gloves. Exposed plugs and filters must be put in a freezer once the sampling is finished.
If the weight of particles on the filter is to be determined, the filter must be weighed before and after sampling.
In this case the filter should be conditioned for 24 hours in a room where temperature and humidity are kept constant before sampling. The filter should be unwrapped from its aluminium foil, which can be used as a bed during weighing. The filter should be wrapped in the same foil after the weighing. When volatile substances such as HCH and HCB are measured, the filter must be weighed after a well-defined period, i.e. ½ to 1 hour in the conditioned room.
After exposure the glass fibre filter containing the particle fraction of the sample is transferred to a 100 ml soxhlet extractor with 250-300 ml 10% diethyl ether/ hexane mixture and an internal standard. The filter is extracted for 6-8 hours.
The PUF plugs are put into a 250 ml soxhlet extractor. This extractor should be mounted on the flask containing the particle extract and extracted for another 6-8 hours.
The filter and the PUF plugs may also be extracted independently in order to quantify the distribution between gas and particle phase. In this case the internal standard should be added to both extractors.
Na2SO4 is added to the extract in order to remove water before further treatment of the samples. When samples are considered to be wet, they should be extracted for 3 hours with acetone, followed by an extraction with diethyl ether/ hexane. These extracts should be combined, dried with Na2SO4, and the volume reduced to 0.5 ml. The amount internal standard to be added depends on the concentration expected in the sample.
Keeper, 20 ml nonane should be added to the extract before evaporation to 0.5 ml with a TurboVap 500. Use A or B speed and 35°C water temperature. The sample is now ready for clean-up as described in the next section.
The sampler is disassembled and glass, metal parts and gaskets are washed using lab detergent (RBS 25) diluted with warm water. The parts, except the gaskets, rinsed well with warm water, thereafter with distilled water and finally with acetone. The gaskets are rinsed well with warm water and distilled water, not with acetone.
8 new plugs are put in a 2000 ml soxhlet extractor and extracted with toluene (24 h), acetone (8 h) and with toluene (8 h). Plugs, which have been previously extracted after sampling, are cleaned using soxhlet extraction with acetone (8 h) and toluene (8 h). After extraction the bulk of the solvent is removed by squeezing the plugs using solvent resistant lab gloves. The plugs are put in a desiccator placed in an oven and dried at 60°C under vacuum (100200 mbar). Following drying the plugs are wrapped individually in aluminium foil. Pairs of plugs are stored in a zip-shut plastic bag together with a glass fibre filter (see below). Storage time should not exceed 6 months. Expiry date is written on a label on the plastic bag and batch number is written in a logbook kept in the cleaning laboratory. A sampling form is put in each plastic bag.
Toluene used in the third cleaning step for cleaning new plugs may be used later in the first cleaning step in order to reduce solvent consumption.
Glass fibre filters are heated in an oven to 450 °C (8 h). After cooling they are wrapped individually in aluminium foil. Storage time should not exceed 6 months.
All glass equipment used for sampling and/or analysis of air, water, deposition, sediment and biological samples must be colour coded in order to separate it from equipment used for samples containing high levels. After use the glass equipment is put in a 2.5% (v/v) water dilution of the lab detergent RBS (16 h). Thereafter it is rinsed 10 times with warm tap water and twice with de-ionised water. Finally the equipment is dried and cleaned in an oven at 450°C (6 h). All glass equipment is rinsed with n-hexane before it is used.
Tweezers used for handling filters and PUF plugs are rinsed well with n-hexane.