Search results
Results From The WOW.Com Content Network
[1] [4] According to IUPAP, "a continued source of annoyance to unit purists has been the continued use of percent, ppm, ppb, and ppt". [5] Although SI-compliant expressions should be used as an alternative, the parts-per notation remains nevertheless widely used in technical disciplines. The main problems with the parts-per notation are set ...
Concentration. In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration. [1] The concentration can refer to any kind of chemical mixture, but most ...
Ultrapure water (UPW), high-purity water or highly purified water (HPW) is water that has been purified to uncommonly stringent specifications. Ultrapure water is a term commonly used in manufacturing to emphasize the fact that the water is treated to the highest levels of purity for all contaminant types, including: organic and inorganic compounds; dissolved and particulate matter; volatile ...
Odor detection value. Odor threshold value (OTV) (also aroma threshold value (ATV), Flavor threshold) is defined as the most minimal concentration of a substance that can be detected by a human nose. Some substances can be detected when their concentration is only few milligrams per 1000 tonnes, which is less than a drop in an Olympic swimming ...
Low concentrations of pollutant gases in air are often expressed in units of ppm or ppb by volume (ppmv and ppbv). Volume-based units refer to the partial volume of the trace gas in the total volume of air. Assuming the ideal gas law, parts by volume is equivalent to parts by molecule count as described in the article.
Air quality monitoring sensors in Port Pirie, South Australia. Air pollution measurement is the process of collecting and measuring the components of air pollution, notably gases and particulates. The earliest devices used to measure pollution include rain gauges (in studies of acid rain), Ringelmann charts for measuring smoke, and simple soot ...
Total organic carbon (TOC) is an analytical parameter representing the concentration of organic carbon in a sample. TOC determinations are made in a variety of application areas. For example, TOC may be used as a non-specific indicator of water quality, or TOC of source rock may be used as one factor in evaluating a petroleum play. [1]
Stripping analysis has the following properties: sensitive and reproducible (RSD<5%) method for trace metal ion analysis in aqueous media, 2) concentration limits of detection for many metals are in the low ppb to high ppt range (S/N=3) and this compares favorably with AAS or ICP analysis, field deployable instrumentation that is inexpensive ...