ABC Drug Analysis flashcards
ABC Drug Analysis · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Presumptive color test
- A rapid chemical screening test that changes color when a drug class is present; it narrows possibilities but cannot identify a substance and requires confirmation by an instrumental method.
- Gas chromatography retention time
- The elapsed time from injection to the maximum of a compound's detector peak under fixed conditions; it is the primary qualitative parameter for identifying an analyte by GC.
- Electron-impact mass spectrum
- A fragmentation pattern produced when molecules are ionized by 70 eV electrons; the molecular ion gives molar mass and fragment ions provide a structural fingerprint for library matching.
- FTIR fingerprint region
- The 1500–400 cm⁻¹ region containing many overlapping absorption bands; a compound is confirmed only when all major bands match the reference spectrum, not a single peak.
- Cocaine HCl versus base
- The hydrochloride salt is water-soluble and organic-insoluble, while the free base (crack) is water-insoluble and organic-soluble; solubility behavior distinguishes the two forms.
- Internal standard
- A known amount of a chemically similar compound added to every sample and standard; it corrects for injection volume and recovery variation during quantitation.
- Cobalt thiocyanate test
- A presumptive color test in which cocaine forms a blue complex with cobalt thiocyanate; the result is screening only and must be confirmed instrumentally.
- Hypergeometric sampling
- A statistical model that estimates the probability of finding at least one positive unit when a random sample is drawn without replacement from a finite seizure population.
- Clandestine lab scene safety
- Entry requires hazard assessment for toxic gases, flammable solvents, and corrosive chemicals; sampling follows documented safety protocols before any evidentiary collection.
- Derivatization in GC-MS
- Chemical conversion of nonvolatile or thermally labile analytes (e.g., amphetamines) into volatile derivatives to improve chromatographic peak shape and mass-spectral specificity.
- Chiral analysis of methamphetamine
- Enantiomer ratio (d- vs l-) is determined by chiral chromatography or chiral derivatization; the ratio can distinguish illicit synthesis from pharmaceutical sources.
- Solvent extraction recovery
- The fraction of analyte transferred from matrix to solvent, determined by comparing extracted samples to unextracted standards; pH and solvent polarity control the recovery.
- Standard addition method
- A quantitation approach in which known analyte increments are added to sample aliquots; the extrapolated intercept gives the original concentration and corrects for matrix effects.
- Chain of custody
- A chronological written record of each person who handled evidence, the date, and the purpose; an unbroken record is required for the evidence to be admissible.
- Schedule I substance
- A controlled substance with high abuse potential and no currently accepted medical use in treatment; examples include heroin and LSD under the federal scheduling system.
- Limit of detection
- The lowest analyte amount that can be reliably distinguished from a blank, typically estimated as three times the standard deviation of blank measurements.
- Limit of quantification
- The lowest analyte amount measurable with acceptable precision and accuracy, commonly taken as ten times the standard deviation of blank measurements.
- Specificity
- The ability of a method to measure only the intended analyte without interference from matrix components or structurally similar compounds present in the sample.
- Measurement uncertainty
- A quantified range around a reported result that accounts for statistical and calibrated-instrument contributions, usually reported at a stated confidence level such as 95%.
- Batch blank
- A negative control processed alongside samples in the same analytical batch; it detects contamination and confirms that reagents and glassware are free of analyte.
- Chromatographic resolution
- A measure of separation between two peaks, calculated as Rs = 2(t2 − t1)/(w1 + w2); Rs of 1.5 or greater indicates baseline resolution.
- Analytical balance verification
- Periodic checking of balance accuracy with certified weights traceable to a national standard, performed before weighing evidence and documented in the record.
- Calibration curve
- A plot of detector response versus analyte concentration for standards of known composition; linear regression of the plot is used to calculate sample concentrations.
- Qualitative versus quantitative
- Qualitative analysis establishes the identity of a substance; quantitative analysis determines how much is present, reported with a calibration curve and uncertainty estimate.
- Federal Schedule II
- A controlled substance with high abuse potential but an accepted medical use, such as methamphetamine or oxycodone; prescribing is tightly restricted and refills are prohibited.
- Blind duplicate sample
- A second aliquot of the same sample submitted under a different identifier; agreement between results assesses precision and detects sample mix-ups.
- Selectivity
- The degree to which a method responds to the analyte of interest relative to other substances in the matrix; it is the qualitative counterpart of specificity.
- Traceability
- The property of a measurement result whereby it can be related to a national or international reference standard through an unbroken chain of documented calibrations.
- Sample homogeneity
- The degree to which analyte concentration is uniformly distributed within a seized material; heterogeneity in tablets or powders affects sampling strategy and result interpretation.
- Confirmatory method
- An analytical technique with high specificity, such as GC-MS or FTIR, that provides structural information sufficient to identify a substance when compared to a reference standard.
- Reference standard
- A well-characterized material of known purity and identity used to calibrate instruments and to compare retention times or spectra during qualitative identification.
- Type A uncertainty
- Uncertainty component evaluated by statistical analysis of repeated measurements, such as the standard deviation of replicate analyses of a sample.