Lassaigne test

Sodium Fusion on Semi mlcro Scale. The Lassaigne test can be readily carried out with as little as 0 01 g. of material, using sodium pellets about 2 mm. in diameter in a tube about 3 x. After fusion, the red-hot tube is plunged into distilled water in a small porcelain crucible or in a boiling tube. The mixture is then heated, filtered and tested as already described. 

Halogens. Proceed as described under the Lassaigne test. If nitro gen is present, the cyanide must first be eliminated. 

Arsenic. The presence of arsenic in an organic compound is generally revealed by the formation of a dull grey mirror of arsenic on the walls of the test-tube when the compound is fusM with sodium in the Lassaigne test. Usually sufficient arsenic is found in the fusion solution to give a yellow precipitate of arsenic trisulphide when the solution is acidified with hydrochloric acid and treated with hydrogen sulphide. 

The mixture of magnesium and potassium carbonate recommended by Castellana as a safe substitute for molten sodium in the Lassaigne test can itself be hazardous,... 

Organic samples for qualitative analysis See LASSAIGNE TEST Other reactants Yoshida, 1980, 262-263 MRH values calculated for 19 combinations with various materials are given. ... 

Lassaigne test, 1039, 1040 defects in, 1043 Lead dioxide, 199 Lead tetracetate, 199, 951 Lessing rings, 92 Leuckart reaction, 561, 567 Liebermann nitroso reaction, 649 Light petroleum, purification of, 174 Ligroin, 174 Linseed oil, 445... 

Organic samples for qualitative analysis See LASSAIGNE TEST (reference 2)... 

Lanthanide iodide silicides, 200 Lanthanide metals, 200 Lanthanide nitrobenzoates, 200 Lanthanide—transition metal alloy hydrides, 201 Lassaigne test, 201 Lead salts of nitro compounds, 201 Lecture demonstrations, 202 Light alloys, 202 Lime fusion, 202 Linseed oil, 202 Liquefied gases, 203 Liquefied natural gas, 203 Liquefied petroleum gases, 203 Liquid air, 204 Liquid nitrogen cooling, 205 Lithium peralkyluranates, 205 Lubricants, 205 Lycopodium powder, 205... 

In a report, Hellwig and coworkers attempted to standardize particular types of caramel by means of the following tests (a) with citric acid, (b) solubility in 65% (v ) ethanol, and (c) the Lassaigne test (see Table 11). They also presented gel-permeation (g. p.) chromatograms (size exclusion chromatography) of various types of caramel. Values of for zones on the chromatograms evidently characteristic for the caramels studied are attributable to color components of caramel. These studies were directed to caramels standardized by ITCA. They allow division of these caramels into ten types and into further subtypes (see Table III). 

Sulfur in nonvolatile organic compounds can easily be converted into alkali sulfide by fusing with an alkali hydroxide in the reducing portion of an alcohol flame. The resulting sulfide is detected by the iodine-azide reaction. The following test is about ten times as sensitive as the Lassaigne test. 

Simple methods of chemical analysis are useful in certain cases. Qualitative chemical tests such as the Beilstein and Lassaigne tests for the presence of particular elements (e.g. halogens, nitrogen, sulphur) are of use in the identification of an unknown polymer. Combustion analysis for quantitative determination of elemental composition can be used to confirm the purity of a homopolymer and to determine the average... 

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