Drug Identification

Drug Identification Screening tests vs. Confirmation • Screening- a test that is nonspecific and preliminary in nature. • Confirmation- a single test that specifically identifies a substance

Drug Identification • Color Tests • Microcrystalline Tests • Chromatography • Spectrophotometry • Mass Spectrophotometry

Marquis(2% formaldehyde in sulfuric acid) Turns purple in presence of opium derivatives Turns orange-brown when mixed with amphetamines and methamphetamines Dillie-Koppanyi(1% cobalt acetate in methanol is 1st added to the suspect material, followed by 5% isopropylamine in methanol) Turns violet-blue in presence of barbiturates. Duquenois-Levine(Solution A a mixture of 2% vanillin and 1% acetaldehyde in ethyl alcohol; sol. B concentrated hydrochloric acid; sol C is chloroform) Turns purple in the presence of marijuana. Van Urk (1% solution of p-dimethylaminobenzaldehyde in 10% concentrated hydrochloric acid and ethyl alcohol) Turns blue-purple in presence of LSD. Scott Test ( solution A is 2% cobalt thiocyanate dissolved in water and glycerine 1:1; solution B is concentrated hydrochloric acid; solution C is chloroform) This is a test for cocaine. Will turn blue in the presence of solution A, pink in the presence of solution B, and back to blue in the presence of solution C. Page 255 Color Tests: Five (5) primary test reagents

Microcrystalline Tests • Test to identify specific substances by the color and morphology of the crystals formed when the substance is mixed with specific reagents. What is a crystalline precipitate?

Microcrystalline Tests • These tests are rapid and often do not require the isolation of the drug from its diluents. • Most color and crystal tests are largely empirical, that is we do not fully understand why they produce the results that they do.

Chromatography • We know it is used to separate mixtures. • Qualitative versus Quantitative Qualitative tells us a substance is a mixture of heroin and quinine Quantitative tells us that mixture is 10% heroin and 90% quinine

Chromatography • The theory of chromatography works due to Henry’s Law. (page 125) • The law states “ When a volatile chemical compound is dissolved in a liquid and is brought to equilibrium with the air, there is a fixed ratio between the concentration of the volatile compound in air and its concentration in the liquid, and this ratio remains constant for a given temperature.

Chromatography : Henry’s Law • An equivalent way of stating the law is that the solubility of a gas in a liquid at a particular temperature is proportional to the pressure of that gas above the liquid. Henry's law has since been shown to apply for a wide range of dilute solutions, not merely those of gases. • An everyday example of Henry's law is given by carbonatedsoft drinks. Before the bottle or can is opened, the gas above the drink is almost pure carbon dioxide at a pressure slightly higher than atmospheric pressure. The drink itself contains dissolved carbon dioxide. When the bottle or can is opened, some of this gas escapes, giving the characteristic hiss (or "pop" in the case of a champagne bottle). Because the pressure above the liquid is now lower, some of the dissolved carbon dioxide comes out of solution as bubbles. If a glass of the drink is left in the open, the concentration of carbon dioxide in solution will come into equilibrium with the carbon dioxide in the air, and the drink will go "flat".

Chromatography What is it and how does it work?

Types of Chromatography • Gas Chromatography (GC) • High Performance Liquid Chromatography (HPLC) • Thin-Layer Chromatography (TLC)

Types of Chromatography:Gas Chromatography • A gas chromatograph is a chemical analysis instrument for separating chemicals in a complex sample. A gas chromatograph uses a flow-through narrow tube known as the column, through which different chemical constituents of a sample pass in a gas stream (carrier gas, mobile phase) at different rates depending on their various chemical and physical properties and their interaction with a specific column filling, called the stationary phase. As the chemicals exit the end of the column, they are detected and identified electronically. The function of the stationary phase in the column is to separate different components, causing each one to exit the column at a different time (retention time). Other parameters that can be used to alter the order or time of retention are the carrier gas flow rate, and the temperature.

Gas Chromatography

Gas Chromatography • Look at page 129 Figure 5-6 shows a chromatogram • GC is highly sensitive and can yield quantitative results. This is seen if compared with a known amount of substance compared with the peaks of the unknown in the chromatogram.

Gas Chromatography • An added extension to GC for forensic scientist is PYROLYSIS gas chromatography. This is where solid physical evidence material such as paint chips, fibers, and plastics which normally can not be dissolved in a gas can be subjected to very high temperatures (500-1000’C) so they will decompose into numerous gaseous products. These can now be ran through a GC to produce a pyrogram. The complexity of the pyrogram serves as a “fingerprint”. See figure 5-7 page 131.

High-Performance Liquid Chromatography (HPLC) • Liquid is used as the ‘moving’ phase through the column instead of gas. • Major advantage is the entire process takes place at room temperature. This helps with organic explosives and drugs that are generally heat sensitive. LSD is an example of such a drug.

Thin-Layer Chromatography (TLC) • Is a SHEET chromatography • Has solid stationary phase and liquid moving phase. • If the sample to be analyzed is solid, it must first be dissolved in a suitable solvent. • Once the liquid has moved a sufficient distance (usually 10cm) the development is complete. • Then it must be visualized. Separation of black ink via TLC

Thin-Layer Chromatography (TLC) To visualize: • Plates can be placed under ultraviolet light revealing those materials that fluoresce as bright spots on dark background. • The plate can be sprayed with a chemical reagent that reacts with the separated substances and causes them to form colored spots.

Thin-Layer Chromatography (TLC)Turn to page 133. See figure 5-9 and 5-10 What is a Rf value? Value defined as the distance traveled by the component divided by the distance traveled by moving liquid phase. In fig 5-10 the moving liquid was allowed to move 10 cm and the heroin moved 8 cm. The Rf value is 8/10 which = .8. The quinine moved 4 cm. What is the Rf value?

Thin-Layer Chromatography (TLC) Powerful tool to forensic scientist due to: • Both rapid and sensitive • Takes less than 100 micrograms for analysis • Minimal costs and space to use • Numerous samples can be analyzed simultaneously

Spectrophotometry • In physics, spectrophotometry is the quantifiable study of electromagnetic spectra. It is more specific than the general term electromagnetic spectroscopy in that spectrophotometry deals with visible light, near-ultraviolet, and near-infrared. Also, the term does not cover time-resolved spectroscopic techniques. • Spectrophotometry involves the use of a spectrophotometer. A spectrophotometer is a photometer (a device for measuring light intensity) that can measure intensity as a function of the color (or more specifically the wavelength) of light. Important features of spectrophotometers are spectral bandwidth and linear range of absorption measurement. Spectrophotometer

Spectrophotometry • Three measurement types • Ultraviolet (UV) • Visible • Infrared (IR) Compare figures 5-16 and 5-17 on page 141 IR provides a much more complex pattern.

Mass Spectrometry • Combination of gas chromatography and mass spectrometry (GC/MS). GC separates the mixture and immediately sends to spectrometer in combination of a computer. Figure 5-18 page 144

Collection / Preservation of drug evidence. • Refer to Appendix I starting on page 543.

Drug Identification