TLC of Barbiturates and Benzodiazepines

Having carried out presumptive tests for these drugs, if a positive result occurs, then further analysis is required. The next phase in the analysis is TLC. Methanol solutions of the drugs can be used, while the standards employed should include the drug which has been suggested through physical examination of the dosage form. However, these drug groups also present some special difficulties in their TLC analysis - these are discussed below. 9.2.3.1 TLC Analysis of Barbiturates In this case,...

Duquenois Levine Reagent for Cannabis Products

The components of this reagent are 2.5 ml of acetaldehyde and 2 g of vanillin dissolved in 100 ml of 95 ethanol (1), concentrated hydrochloric acid (2) and chloroform (3). Testing is carried out as follows. Five drops of solution (1) are added to the material under investigation, which has previously had a drop of ethanol added to it to solubilize the cannabinoids, and the system shaken. Five drops of solution (2) are then added and after shaking again, 10 drops of solution (3) are added. The...

Comparison of Cocaine Samples

The profiling and comparison of cocaine is a complex process, the details of which are beyond the scope of this present book. However, it is useful to consider the compounds which might be present in a sample and how they arise. These include the cocaine content itself, both from the drug and the ecgonines, and other by-products from the process of cocaine synthesis, along with various breakdown products. In addition, there is nor-cocaine, the N-demethylated product which arises as a...

Quantification of Cocaine by UV Spectroscopy

This technique works particularly well if the cocaine is mixed with sugars, from which it can be easily separated by dissolution. Calibration standards are prepared, in methanol solution, at concentrations of 1.0, 0.5, 0.25, 0.125, 0.0625, 0.031 25 and 0.0156 mgml-1, using serial dilutions. A UV spectrum of a holmium filter is first measured to confirm that the instrumental set-up is performing satisfactorily. 0.50 1.00 1.50 2.00 2.50 3.00 3.50 Cocaine (mg ml-1) 0.50 1.00 1.50 2.00 2.50 3.00...

Identification of Herbal Material

Botanically, Cannabis sativa can be identified on the basis of its gross morphological features and, more importantly, by the presence of microscopic structures on the surface of the plant, namely the trichomes. At the macro-morphological level, it has a square stem, with four corners, and has palmate leaves with serrated edges. These are the characteristics with which most people are familiar. Microscopically, three types of trichome are observed, namely the glandular tri-chomes (Plate 4.1),...

Scott Reagent for Cocaine

This is a modification of the previous test, with the reagent consisting of a 2 (wt vol) solution of cobalt isothiocyanate in water, diluted with an equal volume of glycerine (1), concentrated hydrochloric acid (2) and chloroform (3). Testing for cocaine is carried out as follows. A small amount of the material is placed in a test-tube and five drops of component (1) added, when a blue colour will develop if cocaine is present. One drop of concentrated hydrochloric acid (2) is then added and...

Identification of Other Materials

If the morphological characteristics of Cannabis sativa are not all present, or if they have been destroyed, in, for example, resinous material or material that has been smoked (Plate 4.4), it is necessary to identify the material through its phytochemical content. This is also true for hash oil, and all three materials will be considered in the following sections. This involves the identification of the principle drugs which characterize the plant, namely A9-tetrahydrocannabinol (THC), CBD and...

Quantification of Cocaine by GCMS

This method relies on the response of the detector being in direct proportion to the concentration of drug in the sample being evaluated. A series of standards of known concentrations is prepared and analysed, with each analysis being separated by a blank. Why should each sample be separated by a blank in the analytical process The same solution system must be used to prepare both the standards and the samples. Why are internal standards necessary Why is there a requirement to use the same...

Presumptive Tests for Cocaine

There are a number of presumptive tests for cocaine available from the literature. These are described below. 6.3.1.1 The Cobalt Isothiocyanate Test Although there are several presumptive tests available for cocaine and related compounds, none alone is specific to cocaine itself. A very simple test for cocaine is the addition of the material under investigation to a 2 (wt vol) solution of cobalt isothiocyanate in water. The presence of cocaine and related alkaloids results in a blue colour...

Definitive Identification of Cocaine

GC-MS is routinely applied to the identification of cocaine. This is because the technique is both sensitive and of very high resolution. However, this method can also be used on simple mixtures. Trace samples should be obtained by swabbing the surfaces to be examined and subsequently processing the swabs by eluting the drug using methanol or ethanol. Where bulk samples are to be analysed, the sample should be thoroughly homogenized in preparation for this. Derivatization is frequently used and...

Analytical Sequence Bulk and Trace Sampling Procedures

Prior to the process of identifying whether or not a material contains cannabis or its products, a decision must be made as to whether the sample is a bulk or a trace sample. A bulk sample can be defined as anything that can be seen (herbal material, resin or oil), while a trace sample, in terms of cannabis, can be loosely defined as one which would easily be contaminated. Trace samples might be present, for example, on the surfaces of scales used to weigh cannabis materials, the surfaces of...

Identification Quantification and Comparison of Khat Samples

There are few reports in the literature of analyses of material from C. edulis and the only known prosecution for the production of cathine and cathinone from Khat (R. vs. Farmer, Lewes Crown Court, 1998) was unsuccessful 5 . Nevertheless, it is still necessary and useful to understand how to identify, quantify and compare such materials. 7.2.1.1 Identification and Quantification of Khat Basic forensic science principles should be adhered to when carrying out the analysis of a Khat seizure....

Thin Layer Chromatography

Prior to the use of any further method for the analysis of the material and identification of cocaine, the latter must be extracted. For powdered samples, which have been thoroughly homogenized, a 1 mgml-1 solution in methanol will suffice. For herbal material, the situation is rather more complex if the problems associated with extraction of chlorophyll, etc. are to be avoided. One study, where methanol and ethanol alone and in the presence of either diethylamine or ammonia were used,...