Drug Analysis

What is Drugs Analysis?

Within forensic science the role of the drugs section is to prove to a satisfactory level to the court, including the defence, what a substance is and ascertain whether or not it contains any drugs controlled under current legislation. To do this to the level required by the court involves performing a chemical analysis.  As well as determining exactly what drug may be in a given substance (qualitative analysis), further chemical analysis can determine the amount of the drug present and thereby provide the purity of the substance (quantitative analysis).

How We Analyse Drugs

There are a number of steps that a forensic chemist will carry out to analyse a substance.  Initially the chemist will weigh the substance and then take small samples, known as sub-samples, for various analyses. The next step would normally involve carrying out colour tests on one of these sub-samples.  These are simple chemical tests that produce distinctive colours which vary depending on the drug involved, if indeed any drug is present at all. The substance is added to a small amount of reagent and any colour changes that take place can be indicative of the presence of a particular drug type. This simple test, however, does not identify a drug specifically.

To do this the substance would generally be further analysed using gas chromatography-mass spectrometry (GC-MS). This is a combination technique, involving two distinct processes. The first of these, gas chromatography, separates out the different components that make up a given substance. The substance is vaporised and then passed through a column, the coating of which will bind to the individual components of the substance with varying strength. Because of this the components will leave the column at different times as it is heated, producing a chromatograph. The peaks shown on the resulting chromatogram are proportional to the quantity of the substance in the sample which has been analysed.

The second part of this technique, mass spectrometry, involves each of the separated components of the original substance being bombarded with a stream of electrons. This causes the molecules of the component to break up and become ionised. These are then separated by size and charge, the patterns of which can be thought of as a fingerprint for an individual component and used to identify it conclusively.

Following the analysis the forensic scientist prepares a report for the court. This report details the items that have been received and may also include the techniques used in the examination along with the results obtained. If the court requires further information the forensic scientist will attend in their role as an expert witness.

Drug Classification

The use of drugs in the UK is strictly controlled and governed by extensive legislation.  The two key pieces of legislation are the Misuse of Drugs Act, 1971, along with its amendments and modification orders, and the Misuse of Drugs Regulations, 2001.

The Misuse of Drugs Act, 1971 details drugs that are controlled and classifies them A, B or C, reflecting the potential harm they can cause, both in terms of health and social disorder. In general the Act defines what is NOT allowed in respect of these drugs and is continually being revised and amended.


Conversely, The Misuse of Drugs Regulations 2001 lays down what IS allowed. These Regulations define the rules for the use of controlled drugs under appropriate conditions (for example by hospitals and pharmacies).