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One part per trillion (ppt) denotes one part per 1,000,000,000,000 (10 12) parts, and a value of 10 −12. This is equivalent to about thirty seconds out of every million years. This is equivalent to about thirty seconds out of every million years.
1 volume percent = 10,000 ppmv (i.e., parts per million by volume) with a million being defined as 10 6. Care must be taken with the concentrations expressed as ppbv to differentiate between the British billion which is 10 12 and the USA billion which is 10 9 (also referred to as the long scale and short scale billion, respectively).
0.1 × ( 12 ÷ 8 ) = 0.15 grain per dscf when corrected to a gas having a specified reference CO 2 content of 12 volume %. Notes: Although ppmv and grains per dscf have been used in the above examples, concentrations such as ppbv (i.e., parts per billion by volume), volume percent, grams per dscm and many others may also be used.
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, and ...
It is expressed in terms of nano-grams (ng), pico-grams (pg) or femto-grams (fg) with fg being better than pg better than ng. It can also be expressed in terms of parts per billion (ppb), parts per trillion (ppt) or parts per quadrillion (ppq). Sensitivity is important because most explosives have a low vapor pressure .
The word promille is the cognate in Dutch, German, Finnish and Swedish, and is sometimes seen as a loanword in English with the same meaning as per mille. [7] [4] The symbol is included in the General Punctuation block of Unicode at U+2030 ‰ PER MILLE SIGN. [5] There is also an Arabic-Indic per mille sign at U+0609 ؉ ARABIC-INDIC PER MILLE SIGN.
In a photoionization detector, high-energy photons, typically in the vacuum ultraviolet (VUV) range, break molecules into positively charged ions. [2] As compounds enter the detector they are bombarded by high-energy UV photons and are ionized when they absorb the UV light, resulting in ejection of electrons and the formation of positively charged ions.
By using a laser that is locked to an atomic transition, a CCD or PMT will detect the laser induced fluorescence to allow highly selective, parts-per-trillion to parts-per-quadrillion concentration measurement with single atom detection. [1]