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Manual samplers draw a known volume of air through a filter. The filter is weighed on an analytical balance before and after sampling, and the difference in weight divided by the volume of air pulled through the filter gives the mass concentration of the particulate.
An impactor is a device that classifies particles present in a sample of air or gas into known size ranges. It does this by drawing the air sample through a cascade of progressively finer nozzles. The air jets from these nozzles impact on plane sampling surfaces and each stage collects finer particles than its predecessor.
In general, sampling has better detection sensitivity for low levels of airborne radioactivity, due to the much larger total volume of air passing through the filter medium over the sampling interval (which may be on the order of hours), and also due to the more sophisticated forms of quantitative analysis available once the filter medium is ...
Beta attenuation monitoring (BAM) is an air monitoring technique employing the absorption of beta radiation by solid particles extracted from air flow. The technique allows for the detection of PM 10 and PM 2.5 , which are monitored by most air pollution regulatory agencies.
An alternative measurement for particulates, particle number, expresses the concentration in terms of the number of particles per volume of air instead, which can be a more meaningful way of assessing the health harms of highly toxic ultrafine particles (PM 0.1, less than 0.1 μm in diameter).
The instrument was invented in 1957 by Leonard Skeggs, PhD and commercialized by Jack Whitehead's Technicon Corporation. The first applications were for clinical analysis, but methods for industrial and environmental analysis soon followed. The design is based on segmenting a continuously flowing stream with air bubbles.
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Generally, a pipette has optimal accuracy from 35-100% of its nominal volume, and should not be used below 10% of that volume. [5] For example, using a 1,000 μl pipette for 50 μl of liquid is not ideal, and using a 100 μl pipette will give better results.