Drugs: Physiological Changes In The Body - Essay Example

Drugs: Physiological Changes In The BodyIntroductionDrugs are substances which produce some physiological change in the body. They are mostly used for therapeutic purpose for curing some disease. Other uses may involve intentional abuse of such substances. In order to identify drugs, a number of sophisticated analytical methods and tools are available today. Samples of hair, urine, blood, saliva and sweat can be obtained for analysis of drugs and their residues by very sophisticated tests which give accurate results (aboutdrugtesting.org). However some very preliminary chemical tests are available, which can provide a fair indication of the type of drug by a mere color change which can be detected in any chemistry laboratory.

These tests are rapid in action and inexpensive and can be used in conjunction with more precise and elaborate tests for confirmatory diagnosis (Karch, S.B.). Some of these simple tests include color tests or spot tests which are based on the property of some substances to react with chemical reagents to give a specific color which is discernible to the naked eye. With such preliminary tests we can say with a high degree of confidence that the unknown sample we test contains a particular drug.

Some of the simple chemical reagents used for chemical color tests include Liebermann’s reagent, Sulfuric Acid and Ferric chloride reagent. Liebermann’s reagent is prepared by adding 1 gm. Potassium nitrite to 10 ml. of concentrated sulfuric acid. This reagent produces intense color when any drug containing phenols is tested. Typical color displayed when it reacts with Caffeine is yellow; with Ibuprofen, dark red; with Phenacetin, purple to black; with quinine, yellow, and orange with Salicylic acid.

It is also used to detect drugs which are liable for abuse such as Morphine and Cocaine with which it gives black and yellow colors respectively (www.answers.com). Concentrated Sulfuric acid by itself produces a variety of colors when it reacts with some drugs. For example it produces light yellow color when it is mixed with Quinine. Similarly a 5% solution of Ferric chloride produces color changes when it reacts with certain chemical compounds. It reacts to produce yellow color with Caffeine, Ibuprofen, Phenacetin and Quinine and purple color with Salicylic acid.

Such color tests have been developed by chemists along the course of history and give a fair indication of the composition of an unknown substance. However they are not confirmatory tests and modern diagnostic techniques like chromatography and spectrophotometers are used for accurate analysis of an unknown chemical compound. With the multitude of drugs and chemical agents available today, finding the exact chemical composition of an unknown chemical substance is difficult but the modern diagnostic laboratories are equipped with sophisticated instruments for drug analysis and discovery.

Increasing levels of contaminants and chemical residues are present in the air, water and other surroundings which need to be detected under certain circumstances for the toxicological investigations.A spot test can be done with the aid of very basic instruments in an ordinary school chemistry laboratory. A glass tube, a porcelain plate or a simple laboratory filter paper can be used for the purpose. Mere mixing of the unknown substance with the reagent can lead to chemical reactions involving color change which can be interpreted due to already established knowledge about such reactions.

In history the first spot test was developed when it was found that iodine crystals react with starch to show a blue color. This is one of the basic spot tests for starch used till now for detection in feedstuffs (Delly J.G.). The development of spot tests has not been a uniform and methodical research, but chance discoveries which have lead to the development of some of the spot tests described above. All chemicals are either acidic, alkaline or neutral in their chemical properties and this is exploited by the chemists for the detection of salts and elements based on their chemical reaction with other compounds as well as innate capability of eliciting physically discernible changes of color, smell and effervescence.

The color tests are not definite tests and serve the purpose of acting as a simple guide or hint for further analysis with modern techniques for confirmation of the result. REFERENCESAbout Drug Testing, online article available at: http://aboutdrugtesting.org/drug_test.htmDelly J.G., The Literature of Classical Microchemistry, Spot Tests, and Chemical Microscopy, Online article available at: http://www.modernmicroscopy.com/main.asp?article=69&page=2 Karch Steven B., (2006). Drug Abuse Handbook, 2nd Edition, Published by: CRC Press pp 992-993Liebermann Test, Description available at: http://www.answers.com/Liebermann%20test