ABC Drug Analysis key terms

Testing that establishes the identity of a substance, answering what a sample is rather than how much is present. In seized drug work it typically precedes or replaces quantitative measurement.

Testing that determines the amount or concentration of a substance in a sample. Results are usually reported with a measured value, an uncertainty, and the analytical method used.

A rapid screening test that suggests a substance's class but cannot prove identity on its own. A positive result must be followed by a confirmatory method before identification is reported.

An analytical method that provides specific structural or chemical evidence of a substance's identity, such as a mass spectrum or infrared spectrum. It is required to support a reported identification.

A test result indicating a substance is present when it is not. Presumptive color tests are especially prone to this because unrelated compounds can produce similar colors.

The tendency of a reagent or assay to react with compounds other than the target substance, producing a misleading signal. It is a common source of false positives in screening tests.

A presumptive chemical test in which a reagent added to a sample produces a characteristic color change. Examples include cobalt thiocyanate and Marquis reagent.

A presumptive reagent made from formaldehyde in concentrated sulfuric acid that produces colored products with many drugs. It is widely used to screen for opiates and amphetamines.

A presumptive color test in which cobalt thiocyanate reagent turns blue in the presence of cocaine. The color arises from formation of an ion-pair complex.

A presumptive technique in which a reagent is added to a sample on a slide and the resulting crystals are examined under a microscope. Crystal shape and habit help suggest drug identity.

An instrument technique that separates sample components by gas chromatography and identifies each by its mass spectrum. It is a standard confirmatory method in seized drug analysis.

An analytical technique that ionizes molecules, separates the ions by mass-to-charge ratio, and records their abundances. The resulting fragmentation pattern provides highly specific structural information.

The ion formed when a molecule loses or gains an electron without fragmentation, giving a mass corresponding to the intact molecule. Its mass helps establish molecular weight.

The most intense peak in a mass spectrum, assigned a relative abundance of 100 percent. It is used as a reference point for reporting the intensities of other peaks.

An ion produced when a molecular ion breaks apart during ionization. The pattern of fragment ions forms a fingerprint useful for identifying a compound.

The time between sample injection and the detector response for a given compound in a chromatographic run. It is a characteristic value used for tentative identification.

A graph of detector response versus time produced by a chromatographic separation. Each peak typically represents one separated component of the sample.

An analytical technique that measures absorption of infrared light by molecular bonds. The resulting spectrum serves as a distinctive fingerprint for confirming a compound's identity.

A well-characterized material of known identity and purity against which an unknown sample is compared. Matching data to a reference standard supports a confident identification.

One of two or more compounds with the same molecular formula but different structural arrangements. Isomers can be difficult to distinguish and may require comparison to reference standards.

A substance added to a drug to increase bulk or dilute potency, such as lactose, mannitol, or caffeine. Its presence complicates analysis and interpretation of purity.

A substance intentionally added to a drug preparation to alter its effects, appearance, or handling. It differs from a cutting agent, which mainly adds bulk.

The proportion of a sample that consists of the active drug, often reported as a percentage by mass. It requires quantitative analysis and is distinct from simple identification.

A documented procedure describing how many units and how much material are drawn from a seizure for testing. It supports defensible, representative conclusions about the whole exhibit.

A portion of material selected so that its composition reflects the larger exhibit. Proper sampling allows analytical results to be applied to the entire seizure.

The documented, unbroken record of who handled evidence, when, and for what purpose. Gaps or errors can undermine the admissibility and credibility of analytical results.

The condition of evidence being unaltered, properly sealed, and accounted for from seizure through testing and storage. It is protected by seals, logs, and secure storage.

A drug or chemical whose manufacture, possession, or use is regulated by law because of abuse potential or health risk. Schedules classify these substances by relative risk and accepted medical use.

The legal classification of controlled substances into ranked categories based on abuse potential, medical usefulness, and safety. Placement determines the penalties and controls that apply.

A compound structurally similar to a controlled substance that may produce comparable effects. Some laws treat certain analogs as controlled to prevent minor chemical modifications from escaping regulation.

A substance synthesized or selected to mimic the effects of a controlled drug while evading existing legal controls. Its structure is often a slight modification of a known compound.

The study of how substances interact with living systems, including their effects, mechanisms, and fate in the body. It provides context for understanding why drugs are controlled.

A product formed when a drug is chemically changed by the body. Metabolites can appear in biological samples and may be targeted in toxicological analysis.

Initial testing of samples to sort out which contain a target substance or class before more specific analysis. Screening results are presumptive and require confirmation.

A written, approved protocol describing how a laboratory performs a specific task. Following it supports consistency, traceability, and defensible results.

The set of checks, standards, and practices used to ensure analytical results are accurate and reliable. It includes blanks, controls, and calibration verification.

A graph relating instrument response to known concentrations of a standard. It is used to quantify unknown samples and to verify that measurements fall within a valid range.

The smallest amount of a substance that can be reliably distinguished from background signal by a method. It defines the lowest level at which a method can report presence.

The smallest amount of a substance that can be measured with acceptable accuracy and precision. It is generally higher than the limit of detection.