Lieben test

Hypoiodites are used for qualitative tests for methyl ketones (Lieben test). For this purpose, a compound to be tested is stirred with an aqueous solution of sodium hydroxide (80 mol/mol of methyl ketone). Iodine (4.5 mol of 12) is added portionwise with stirring, and the mixture is set aside for 20 min at 25 °C before acidification. In the presence of a methyl keto group, a yellow heavy precipitate of iodoform settles at the bottom of the test tube. Iodoform can be identified easily not only by its characteristic smell but also by its melting point (120-123 °C) [1173], This test applies not only to methyl ketones but to any compound that can be converted in the reaction medium into a species containing the COCH3 group, for example, isopropyl or ethyl alcohol. 

Newer methods of chemical analysis led to the isolation of the major alkaloids from crude drug preparations. By 1833, aconitine, atropine, codeine, hyoscyamine, morphine, nicotine, and strychnine had been isolated from plants. Color tests for alkaloids were developed between 1861 and 1882 by 1890 quantitative analysis methods became available. Physiological tests for alkaloids, particularly strychnine, first used in 1856, were employed well into the twentieth century. Tests for alcohol, devised by Lieben (iodoform crystal test, 1870) and others, were later perfected for the quantitative analysis of alcohol in body fluids and tissues. Qualitative tests for carbon monoxide in the blood were developed about this time and in 1880, Fodor developed a palladium chloride reduction method to quantitate carbon monoxide in blood. 

McKee etal. 1943 WHO 1979). For the present, the biomarker that correlates best with exposure is measurement of metabolites in the urine. The iodine-azide and TTCA tests can be conducted to measure urinary levels of carbon disulfide metabolites as they have been shown to correlate with exposure (Baselt 1980 Beauchamp et al. 1983 Campbell et al. 1985 Lieben 1974 WHO 1986), with the TTCA test being more sensitive and specific than the iodine-azide test. 

At the present time, the biomarkers that correlate best with exposure are metabolite levels in the urine (Baselt 1980 Beauchamp et al. 1983 Campbell et al. 1985 Lieben 1974 WHO 1986). The iodine-azide and the TTCA tests, which measure the presence of urinary carbon disulfide metabolites, have been shown to correlate well with actual exposure. However, the iodine-azide test is nonspecific (Dox et al. 1992). TTCA is produced in humans after exposure to Antabuse and in rats after exposure to Captan (Cox et al. 1992). Moreover, other investigations are necessary in order to determine whether the interaction of carbon disulfide with other substances (such as hydrogen sulfide, drugs, carbon tetrachloride, malathion, and alcohol), disease states, and variations in diet and in individual metabolism, as well as other factors, could confound the results of the iodine-azide test and the TTCA test for carbon disulfide exposure. Baseline urine, breath, and blood samples are necessary to correct for non-workplace exposures. For exposures around hazardous waste sites, the influence of workplace exposures must also be corrected for in this manner. 

When iodine is used the reaction serves for recognition of a group RCOCH3 (R = H, alkyl, or aryl) or of a group such as ethanol that is oxidizable to RCOCH3 by hypoiodite (Lieben s iodoform test) ... 

Robert s dissertation advisers were both good friends of Albert Einstein Hans Thirring, whose Lense-Thirring equation had provided a method for testing Einstein s special theory of relativity, and Felix Ehrenhaft, who had provided support for Einstein s theory of Brownian motion by making observations of the movement of silver particles in air (which brought him the Lieben Prize of the Vienna Academy of Sciences). For his postdoctoral research topic Robert approached Thirring, chair of the Institute for Theoretical Physics, who directed him to Herman Mark in the First Chemical Laboratory of the University of Vienna. 

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