Halogens detection

COCI2), nickel tetracarbonyl (Ni(CO)3), inorganic arsenic compoimds, chloroformates and halogens. Detection of some Choking Agents with PIDs or FIDs may be possible. Detection and identification with FT-IR is possible provided that the appropriate reference spectra are available. 

Standard halogen detecting devices can be used to find sulfur hexafluoride leaks and can help locate extremely small leaks. This equipment will detect concentrations in the parts per billion (ppb) range. 

Halogen detection. To a portion of the filtrate add excess of dilute nitric acid and boil in an evaporating basin for 10 minutes, or to half bulk, in order to remove any sulphide or cyanide, which interfere in the following test. Cool, and add dilute silver nitrate solution. A white or yeUow precipitate indicates the presence of chloride, bromide or iodide either singly or in admixture. 

Advantages Can be used for capillary chromatography. Selectivity can be chosen for halogens, amines, nitrogen and sulfur. High sensitivity at high selectivity. Can be used for halogen detection without a source of radioactivity, therefore no authorization necessary. Simple calibration, as the response is directly proportional to the number of heteroatoms in the analyte, for example, the proportion of Cl in the molecule. 

Beilstein s test A method for detecting the presence of halogen in an organic compound. A piece of copper gauze is heated in an oxidiz-... 

The Sodium Carbonate-Zinc Method for Detecting Nitrogen, Halogens and Sulphur in Organic Compounds. 

If C, H and a halogen (but no nitrogen) have been detected, and the substance is freely soluble in (or readily hydrolysed by) cold water, then O must also be present. 

Sulphur, as sulphide ion, is detected by precipitation as black lead sulphide with lead acetate solution and acetic acid or with sodium plumbite solution (an alkaLine solution of lead acetate). Halogens are detected as the characteristic silver halides by the addition of silver nitrate solution and dilute nitric acid the interfering influence of sulphide and cyanide ions in the latter tests are discussed under the individual elements. 

THE SODIUM CARBONATE - ZINC METHOD FOR THE DETECTION OF NITROGEN, SULPHUR AND HALOGENS IN ORGANIC COMPOUNDS... 

When an organic compound is heated with a mixture of zinc powder and sodium carbonate, the nitrogen and halogens are converted into sodium cyanide and sodium hahdes respectively, and the sulphur into zinc sulphide (insoluble in water). The sodium cyanide and sodium hahdes are extracted with water and detected as in Lassaigne s method, whilst the zinc sulphide in the residue is decomposed with dilute acid and the hydrogen sulphide is identified with sodium plumbite or lead acetate paper. The test for nitrogen is thus not affected by the presence of sulphur this constitutes an advantage of the method. 

Reference methods for criteria (19) and hazardous (20) poUutants estabHshed by the US EPA include sulfur dioxide [7446-09-5] by the West-Gaeke method carbon monoxide [630-08-0] by nondispersive infrared analysis ozone [10028-15-6] and nitrogen dioxide [10102-44-0] by chemiluminescence (qv) and hydrocarbons by gas chromatography coupled with flame-ionization detection. Gas chromatography coupled with a suitable detector can also be used to measure ambient concentrations of vinyl chloride monomer [75-01-4], halogenated hydrocarbons and aromatics, and polyacrylonitrile [25014-41-9] (21-22) (see Chromatography Trace and residue analysis). 

Fluorine is a pale yellow gas that condenses to a yellowish orange Hquid at — 188°C, sohdifies to a yellow soHd at —220°C, and turns white in a phase transition at —228° C. Fluorine has a strong odor that is easily detectable at concentrations as low as 20 ppb. The odor resembles that of the other halogens and is comparable to strong o2one (qv). 

Fluorine in the atmosphere can be detected by chemical methods involving the displacement of halogens from haUdes. Dilute fluorine leaks are easily detected by passing a damp piece of starch iodide paper around the suspected area. The paper should be held with metal tongs or forceps to avoid contact with the gas stream and immediately darkens when fluorine is present. 

Volatile impurities, eg, F2, HF, CIF, and CI2, in halogen fluoride compounds are most easily deterrnined by gas chromatography (109—111). The use of Ftoroplast adsorbents to determine certain volatile impurities to a detection limit of 0.01% has been described (112—114). Free halogen and haHde concentrations can be deterrnined by wet chemical analysis of hydrolyzed halogen fluoride compounds. 

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