Rafael, Dune Vienis Karen N. November 20, 2009BS-Pharmacy 4A Toxicology Lab

Activity No. 01PHOSPHOROUS

II. DATA:

Type of Test/Method of Detection

Observations/Data

1. Scherer’s Preliminary Test The paper strip moistened with silver nitrate is darkened in black color (Warren, 1920).Blank: No discoloration is observed.

2. Mitscherlich’s Method A luminous ring or band in the upper part of the condenser appeared. Chemiluminescence during distillation with steam is very characteristic of yellow phosphorous (Warren, 1920).Blank: No change observed.

3. Confirmatory Test to Detect Phosphoric Acida. Ammonium Molybdate

TestA yellow precipitate was formed (Warren, 1920).Blank: No precipitation was observed.

b. Magnesia Mixture Test/ Ammonium Magnesium Phosphate Test

A white crystalline precipitate was produced after vigorous shaking (Warren, 1920). Blank: No production of any precipitate occurred.

Data Analysis:

The principle of Scherer’s Test is that moist phosphorous vapor and silver nitrate form black silver phosphide (Ag3P), metallic silver, phosphoric and sometimes phosphorous acid. If the silver but not the lead paper is darkened, yellow phosphorous may be present. If both papers are darkened, hydrogen sulfide also is present. In the latter case yellow phosphorous may be present with hydrogen sulfide. In absence of hydrogen sulfide, darkening of the silver paper is not final proof of yellow phosphorous, for any volatile organic substance having reducing properties, as formaldehyde, or formic acid, may give the same result. Scherer’s Test is of value in proving the absence rather than the presence of yellow phosphorous. It is a good preliminary test, as it excludes phosphorous if the silver paper is unchanged (Warren, 1920).

The principle of Mitscherlich’s Method is that yellow phosphorous volatilizes with steam and becomes luminous in contact with air. The chemiluminescence is best seen in a dark room. Chemiluminescence usually appears as a luminous ring or band in the upper part of the condenser. When this is distinctly visible, the presence of yellow phosphorous is established. Chemiluminescence during distillation with steam is very characteristic of yellow phosphorous and frequently is the only sure and unquestionable test for this element (Warren, 1920).

When prolonged distillation fails to give a positive result, this must not be accepted as final proof of the absence of phosphorous until other tests have been made. Whatever the result,

confirmatory tests such as the Ammonium Molybdate Test and Ammonium Magnesium Phosphate Test (Magnesia Misture Test) should be conducted. Phosphoric acid precipitates yellow ammonium phosphor-molybdate in Ammonium Molybdate Test. Phosphoric acid gives a white crystalline precipitate of ammonium magnesium phosphate (H4N)-MgPO4.6H2O. When only traces of phosphoric acid are present, long standing is necessary before the precipitate appears. The precipitate should be examined with the microscope. It should consist a well-formed crystal or at least should be crystalline. These crystals are transparent, acicular prisms (Warren, 1920).

III. ANSWERS TO QUESTIONS:1. Why are we concerned about phosphorous?

Phosphorous, aside from being an essential trace element in the human body, it is also an essential plant nutrient. It finds its major use as a constituent of fertilizers for agriculture and farm production in the form of concentrated phosphoric acids, which can consist of 70% to 75% of phosphorous oxide (Wikipedia, 2009). Pesticides and fertilizers are the preferred method for suicide for residents of underdeveloped countries (Clarke, 1993). Therefore, we are concerned about phosphorus because it is a possible source of intoxication due to homicidal, accidental and suicidal reasons. As future pharmacists, we have the reason to be concerned since it is a part of our duty to detect, identify and manage any cases of intoxication.

2. List down environmental hazards caused by phosphorous.

Among the environmental hazards caused by phosphorous are: Explosive Gives off irritating odor or fumes Contaminates drainages and watercourses, harming fresh water and marine life.

IV. CONCLUSION:

Yellow phosphorus is a poisonous, flammable, gives off fumes, and evolves a peculiar garlicky odor, luminous in the dark, and preserved as transparent sticks. Phosphorous, aside from being an essential trace element in the human body, it is also an essential plant nutrient. It finds its major use as a constituent of fertilizers for agriculture and farm production. Since fertilizers are among the preferred method for suicide and homicide. The management of phosphorous intoxication poses a concern for pharmacists, toxicologists and physicians. In order to detect the presence of phosphorus in organ tissue specimens, tests of different method and principles are conducted. These tests are Scherer’s Preliminary Test, Mitscherlich’s method, Ammonium molybdate test and magnesia mixture test. Since phosphorus is explosive, obnoxious and can contaminate drainages and watercourses, proper waste disposal is needed to prevent environmental harm.

V. Gallery

Figure 1.1. Scherer’s test setup. Strips of silver nitrate and lead acetate solution are separately suspended in the mouth of the flask. The distillate is warmed gently upon a water bath of about 40 to 50 degrees Celsius (Warren, 1920).

Figure 1.2. Mitscherlich Apparatus. The condenser is supported in a vertical position and connected to the upper end with the flask by a glass tube about 8mm. internal diameter. This tube has two right-angle bends and each end passes through a cork (Warren, 1920).

Figure 1.3. Ammonium magnesium phosphate crystals as examined in the microscope. These

crystals are transparent, acicular prisms