tailieunhanh - Drugs and Poisons in Humans - A Handbook of Practical Analysis (Part 5)

Introduction: The advancement of technologies was marvelous during the past half century; new analytical instruments have been being invented and improved. About 30 years ago, thin-layer chromatography (TLC) was being used most widely for detection and identification of drugs and poisons. Around that time, the use of GC/MS started in the field of medicine. Therefore, an ideal procedure for analysis of drugs and poisons was considered to be the screening by TLC, followed by the final identification and quantitation by GC/MS. However, recently, various enzyme immunoassays for drugs without need of pretreatments have appeared, and some disposable drug screening kits. | Detection methods By Osamu Suzuki Introduction The advancement of technologies was marvelous during the past half century new analytical instruments have been being invented and improved. About 30 years ago thin-layer chromatography TLC was being used most widely for detection and identification of drugs and poisons. Around that time the use of GC MS started in the field of medicine. Therefore an ideal procedure for analysis of drugs and poisons was considered to be the screening by TLC followed by the final identification and quantitation by GC MS. However recently various enzyme immunoassays for drugs without need of pretreatments have appeared and some disposable drug screening kits have become available resulting in a great change of analytical procedure for unknown toxins in human samples. Figure shows a flowchart of the current analytical procedure for human specimens. For the details of Flowchart of analytical methods for drugs and poisons. Springer-Verlag Berlin Heidelberg 2005 34 Detection methods preliminary spot or color tests the readers can refer to a new book 1 which has been published very recently. Thin-layer chromatography TLC TLC is a method of chromatography in which a thin-layer made of silica gel alumina florisil or cellulose is coated on glass or aluminum plates. Numerous types of TLC ready for use without the need of pretreatments are commercially available. An extract fluids is spotted onto a bottom area of a plate. After drying the spot the plate is developed with a mobile phase consisting of various ratios of organic solvents acids and or water. During the development with a mobile phase a compound spotted moves at a certain speed towards the top. The movement of a compound to be analyzed is usually expressed by Rf values distance which a compound travels from the origin distance which a solvent front travels from the origin . This method requires no expensive instruments and is very simple. Since relatively many samples can be .