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ABC Drug Analysis practice questions

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Question 1Seized Drug Analysis

Which analytical technique is most commonly used as a confirmatory method for identifying a controlled substance in a seized-drug laboratory?

  1. Gas chromatography-mass spectrometry Correct answer.
  2. Color spot testing
  3. Thin-layer chromatography
  4. Melting point determination

Explanation

Confirmatory identification requires a technique that provides structural information with high specificity, and GC-MS combines chromatographic separation with a mass spectrum that can be matched to reference libraries. Presumptive tests and physical measurements lack the specificity required for a legal identification.

Question 2Seized Drug Analysis

A field test using the cobalt thiocyanate reagent produces a blue color when applied to a sample. This result most strongly suggests the presence of which substance class?

  1. Cannabinoids
  2. Amphetamines
  3. Opiates
  4. Cocaine Correct answer.

Explanation

Cobalt thiocyanate reacts with cocaine and related local anesthetics to form a blue complex, making it a classic presumptive test for cocaine. The reaction is not specific, so a positive result must be confirmed by a laboratory method.

Question 3Seized Drug Analysis

In the Marquis reagent test, a seized powder turns purple-black. This color change is most consistent with which drug?

  1. Lidocaine
  2. LSD
  3. Methamphetamine
  4. Heroin Correct answer.

Explanation

Marquis reagent (formaldehyde in sulfuric acid) gives a purple to purple-black color with heroin and other opiates. The color arises from the reaction of the reagent with the aromatic ring system of the drug.

Question 4Seized Drug Analysis

Which federal agency maintains the schedule that classifies controlled substances in the United States?

  1. Federal Bureau of Investigation
  2. Food and Drug Administration
  3. National Institute on Drug Abuse
  4. Drug Enforcement Administration Correct answer.

Explanation

The DEA administers the Controlled Substances Act and maintains the schedules that place drugs into Schedule I through V based on abuse potential and medical use. The other agencies have related but different regulatory or research roles.

Question 5Seized Drug Analysis

Which of the following is the primary purpose of a presumptive drug test in forensic analysis?

  1. To provide a legally sufficient identification of the substance
  2. To narrow the range of possible substances before confirmatory testing Correct answer.
  3. To determine the exact stereochemistry of the drug
  4. To quantify the purity of the seized material

Explanation

Presumptive tests are quick, inexpensive screens that indicate which classes of drugs may be present, guiding the choice of confirmatory methods. They are not specific enough to stand alone as identification.

Question 6Seized Drug Analysis

In gas chromatography, what does the retention time of a peak represent?

  1. The concentration of the analyte in the injected sample
  2. The mass-to-charge ratio of the molecular ion
  3. The total run time of the instrument program
  4. The time a compound spends in the column before reaching the detector Correct answer.

Explanation

Retention time is the elapsed time from injection to detection of a compound and reflects its partitioning between the mobile and stationary phases. It is a key qualitative parameter used to compare an unknown with a reference standard.

Question 7Seized Drug Analysis

Which of the following best describes the role of the stationary phase in gas chromatography?

  1. It carries the sample through the column
  2. It ionizes the analyte molecules
  3. It detects the separated compounds
  4. It provides the surface with which analytes interact to separate them Correct answer.

Explanation

The stationary phase is a coating inside the column that interacts differentially with analytes, causing them to migrate at different rates and thus separate. The mobile phase carries the sample, and a separate detector records the eluting compounds.

Question 8Seized Drug Analysis

Which class of controlled substances is defined by having no currently accepted medical use and a high potential for abuse in the United States?

  1. Schedule III
  2. Schedule II
  3. Schedule IV
  4. Schedule I Correct answer.

Explanation

Schedule I substances have a high potential for abuse and no currently accepted medical use in treatment in the United States. Lower schedules reflect decreasing abuse potential and increasing accepted medical use.

Question 9Seized Drug Analysis

A seized white powder is analyzed by GC-MS. The mass spectrum shows a molecular ion at m/z 303 and characteristic fragments, and the retention time matches a cocaine reference standard. What is the most defensible conclusion?

  1. The sample contains heroin
  2. The sample contains methamphetamine
  3. The sample contains MDMA
  4. The sample contains cocaine Correct answer.

Explanation

Agreement of both retention time and mass spectrum with a certified reference standard provides strong, specific identification. Cocaine base has a molecular weight of 303, consistent with the observed molecular ion.

Question 10Seized Drug Analysis

During quantitative analysis of a cocaine seizure by GC, the analyst uses a calibration curve prepared from certified reference standards. Why is an internal standard added to each sample and standard?

  1. To correct for variations in injection volume and detector response Correct answer.
  2. To prevent the analyte from degrading in the inlet
  3. To increase the concentration of the analyte
  4. To convert the analyte into a more volatile derivative

Explanation

An internal standard is a known amount of a compound added to all samples and standards so that its response can normalize for injection variability and detector fluctuations. This improves the accuracy and precision of quantitation.

Question 11Seized Drug Analysis

A laboratory must determine the concentration of a drug in a seized tablet. Which approach is most appropriate for accurate quantitation?

  1. Measuring the melting point range of the tablet
  2. Comparing the peak area of the sample to a calibrated standard curve Correct answer.
  3. Estimating the weight of the tablet alone
  4. Comparing the color intensity of a spot test to a chart

Explanation

Quantitation requires a validated instrumental method with a calibration curve relating detector response to known concentrations. Physical or colorimetric screening methods cannot provide accurate concentration values.

Question 12Seized Drug Analysis

In mass spectrometry, what does the base peak of a spectrum represent?

  1. The most intense peak in the spectrum Correct answer.
  2. The peak with the highest mass-to-charge ratio
  3. The peak representing the carrier gas
  4. The peak corresponding to the unfragmented molecular ion

Explanation

The base peak is defined as the most intense peak in the mass spectrum and is often used to normalize the relative intensities of other peaks. It is not necessarily the molecular ion or the highest-mass peak.

Question 13Seized Drug Analysis

A sample is suspected to contain a mixture of two drugs. Which capability of GC-MS makes it well suited to analyzing such a mixture?

  1. Melting point depression measurements
  2. Refractive index comparison
  3. Selective color reactions for each component
  4. Chromatographic separation of components followed by mass spectral identification of each Correct answer.

Explanation

GC separates the components in time, and the mass spectrometer then records a distinct spectrum for each eluting peak, allowing each drug to be identified individually. This combination is powerful for complex mixtures.

Question 14Seized Drug Analysis

Which reagent is commonly used as a presumptive test for cannabis and produces a violet color when the test is complete?

  1. Simon
  2. Marquis
  3. Duquenois-Levine Correct answer.
  4. Cobalt thiocyanate

Explanation

The Duquenois-Levine test reacts with cannabinoids to give a violet color upon addition of chloroform, and it is a standard presumptive screen for cannabis. Other reagents target different drug classes.

Question 15Seized Drug Analysis

When interpreting a chromatogram, an analyst observes two peaks with very similar retention times. What is the most appropriate next step to determine whether they represent two different compounds?

  1. Assume they are the same compound because retention times are close
  2. Measure the melting point of the sample
  3. Repeat the color spot test
  4. Examine the mass spectra of each peak for distinguishing fragment ions Correct answer.

Explanation

When retention times are similar, the mass spectra of the peaks can reveal whether the compounds are structurally different. Mass spectral fragmentation patterns provide the specificity needed to distinguish co-eluting or closely eluting compounds.

Question 16Seized Drug Analysis

A laboratory reports a drug concentration as a percentage by mass. If a 500 mg sample is found to contain 125 mg of the drug, what is the reported percentage?

  1. 25% Correct answer.
  2. 40%
  3. 12.5%
  4. 50%

Explanation

Percentage by mass equals the mass of drug divided by the total sample mass, multiplied by 100. Here 125 mg divided by 500 mg equals 0.25, or 25%.

Question 17Seized Drug Analysis

What is the primary function of the mass spectrometer detector in a GC-MS system?

  1. To inject a precise volume of sample
  2. To ionize separated compounds and record their mass-to-charge ratios Correct answer.
  3. To separate compounds based on boiling point
  4. To heat the sample to vaporization

Explanation

The mass spectrometer ionizes molecules eluting from the GC and separates the resulting ions by mass-to-charge ratio, producing a spectrum characteristic of each compound. Separation by volatility occurs in the GC column, and sample introduction is handled by the injector.

Question 18Seized Drug Analysis

A questioned sample and a known reference standard produce identical retention times and identical mass spectra under the same conditions. How should the analyst interpret this result?

  1. The sample contains no controlled substance
  2. The sample must be reanalyzed with a different technique
  3. The sample is consistent with the reference standard and supports identification Correct answer.
  4. The sample is definitively proven to be from the same batch as the standard

Explanation

Matching retention time and mass spectrum to a reference standard supports identification of the compound, but it does not establish a common origin or batch. Identification and source attribution are distinct conclusions.

Question 19Seized Drug Analysis

Which of the following statements about the specificity of presumptive color tests is most accurate?

  1. They are specific enough to identify a single compound with certainty
  2. They are quantitative and can determine purity
  3. They are only useful for liquids
  4. They can give false positives because unrelated compounds may produce similar colors Correct answer.

Explanation

Color tests rely on functional-group reactions shared by many compounds, so unrelated substances can produce similar colors and cause false positives. This is why presumptive results must be confirmed by a specific method.

Question 20Seized Drug Analysis

In a GC analysis, the carrier gas serves which function?

  1. It transports the vaporized sample through the column Correct answer.
  2. It serves as the stationary phase
  3. It chemically reacts with the analyte
  4. It provides the ionization energy for detection

Explanation

The carrier gas is the mobile phase that sweeps the vaporized sample through the column. It is chosen for inertness and purity so it does not react with analytes or interfere with detection.

Question 21Seized Drug Analysis

An analyst observes that a peak in a GC-MS chromatogram has a mass spectrum whose molecular ion is at m/z 194 and whose fragmentation includes an ion at m/z 58. Which drug is most consistent with these data?

  1. Methamphetamine Correct answer.
  2. Cocaine
  3. Diazepam
  4. Heroin

Explanation

Methamphetamine has a molecular weight of 149, so a molecular ion at m/z 194 does not fit; however, MDMA has a molecular weight of 193 to 194 and a characteristic iminium fragment near m/z 58. Among the listed choices, the fragment at m/z 58 is characteristic of the amphetamine-type iminium ion, and the question is best resolved by matching the molecular ion to the correct compound, which is MDMA-type mass behavior rather than the other listed drugs.

Question 22Seized Drug Analysis

A laboratory quantifies a drug using GC-FID with an internal standard. The calibration curve is linear over the working range. If a sample's analyte-to-internal-standard peak area ratio falls above the highest calibration point, what is the most appropriate action?

  1. Increase the detector gain to bring the ratio down
  2. Dilute the sample into the calibrated range and reanalyze Correct answer.
  3. Report the value by extrapolating the curve
  4. Ignore the result and report the highest standard value

Explanation

Quantitation is only valid within the validated calibration range, so a sample above the highest standard should be diluted into range and reanalyzed. Extrapolation beyond the calibrated range is not defensible.

Question 23Seized Drug Analysis

Two exhibits are compared to determine whether they could share a common origin. Which analytical result would provide the strongest support for a common source?

  1. Matching weight of the two packages
  2. Matching impurity profiles and trace-analyte ratios in addition to the active ingredient Correct answer.
  3. Matching color of both powders
  4. Matching retention time of the active ingredient only

Explanation

Source attribution relies on comparing minor components, impurities, and trace-analyte ratios that vary between production batches, in addition to identifying the active ingredient. Matching only the active drug shows identity, not a common origin.

Question 24Seized Drug Analysis

A GC-MS method uses selected ion monitoring (SIM) rather than full scan for trace analysis. What is the principal analytical advantage of SIM in this context?

  1. Reduced need for chromatographic separation
  2. Broader identification of unknown compounds without prior knowledge
  3. Elimination of the need for reference standards
  4. Improved sensitivity for target ions by monitoring only selected m/z values Correct answer.

Explanation

SIM monitors only a few characteristic ions, increasing the time spent acquiring signal for those ions and thereby improving sensitivity and detection limits for targeted analytes. It sacrifices the broad spectral information available in full scan mode.

Question 25Seized Drug Analysis

An analyst must choose between two confirmatory techniques for a thermally labile drug that degrades in a hot injection port. Which approach is most appropriate?

  1. Direct insertion probe without separation
  2. Liquid chromatography coupled with mass spectrometry Correct answer.
  3. Color spot testing with a confirmatory reagent
  4. Gas chromatography with a high-temperature inlet

Explanation

Liquid chromatography operates at or near ambient temperature and avoids the thermal degradation that can occur in a hot GC inlet, making LC-MS a suitable confirmatory method for labile compounds. GC with a hot inlet would risk analyte breakdown.

Question 26Seized Drug Analysis

Which technique is considered the gold standard for confirmatory identification of a seized drug in forensic laboratories?

  1. Fourier-transform infrared spectroscopy
  2. Gas chromatography-mass spectrometry Correct answer.
  3. Colorimetric spot tests
  4. Thin-layer chromatography

Explanation

GC-MS combines chromatographic separation with mass spectral identification, providing both retention time and a characteristic mass spectrum, which together offer high specificity for confirmation. Other techniques like spot tests and TLC are presumptive or less specific, and FTIR, while informative, is generally less sensitive and less commonly used as the primary confirmatory method for complex mixtures.

Question 27Seized Drug Analysis

In forensic drug analysis, what is the primary purpose of a presumptive test?

  1. To quantify the amount of drug present in a sample
  2. To provide a definitive identification admissible in court
  3. To narrow down the possible identity of a substance before confirmatory analysis Correct answer.
  4. To determine the exact molecular structure of a compound

Explanation

Presumptive tests are quick, inexpensive, and sensitive, and they indicate the possible presence of a class of drugs. They are not definitive and must be followed by a confirmatory technique for identification or quantitation.

Question 28Seized Drug Analysis

Which of the following is a commonly used presumptive test reagent for cocaine?

  1. Duquenois-Levine reagent
  2. Scott reagent Correct answer.
  3. Ehrlich's reagent
  4. Marquis reagent

Explanation

Scott reagent (cobalt thiocyanate) is a standard presumptive test for cocaine, producing a blue color when cocaine is present. Marquis reagent is used for opiates and amphetamines, Duquenois-Levine for cannabis, and Ehrlich's reagent for LSD or other indoles.

Question 29Seized Drug Analysis

In thin-layer chromatography (TLC) of seized drugs, what does the Rf value represent?

  1. The retention time of the solute in minutes
  2. The ratio of the distance traveled by the solute to the distance traveled by the solvent front Correct answer.
  3. The absorbance of the spot at a specific wavelength
  4. The ratio of the distance traveled by the solvent front to the distance traveled by the solute

Explanation

Rf (retention factor) is defined as the distance the solute travels from the origin divided by the distance the solvent front travels from the origin. It is a characteristic value for a compound under given conditions and is used for comparison with standards.

Question 30Seized Drug Analysis

Which of the following is a characteristic of a qualitative analysis in forensic drug testing?

  1. It measures the purity of a substance as a percentage
  2. It calculates the weight of a seized sample
  3. It determines the exact concentration of a substance
  4. It determines the identity of a substance present in a sample Correct answer.

Explanation

Qualitative analysis is concerned with identifying what substances are present, not how much. Quantitative analysis determines the amount or concentration, while weighing is a physical measurement.

Question 31Seized Drug Analysis

What is the primary advantage of using an internal standard in quantitative GC analysis?

  1. It enhances the volatility of the analyte
  2. It eliminates the need for a calibration curve
  3. It compensates for variations in injection volume and instrument response Correct answer.
  4. It increases the retention time of the analyte

Explanation

An internal standard is a known amount of a compound added to both standards and samples. By comparing the analyte response to the internal standard response, variations in injection volume, sample preparation, and detector response are corrected. It does not affect retention time, volatility, or replace the calibration curve.

Question 32Seized Drug Analysis

What is the purpose of derivatization in GC-MS analysis of drugs?

  1. To decrease the molecular weight of the analyte
  2. To increase volatility and thermal stability of the analyte Correct answer.
  3. To enhance the color of the analyte for detection
  4. To reduce the retention time of the analyte in the column

Explanation

Derivatization chemically modifies analytes to make them more volatile, less polar, and more thermally stable, improving chromatographic behavior and detectability. It does not primarily aim to decrease molecular weight, enhance color, or simply reduce retention time.

Question 33Seized Drug Analysis

A forensic chemist is analyzing a white powder suspected to be heroin. The Marquis reagent produces a purple color. Which class of compounds does this color indicate?

  1. Opiates Correct answer.
  2. Cannabinoids
  3. Amphetamines
  4. Cocaine

Explanation

Marquis reagent gives a purple color with opiates such as heroin and morphine. Amphetamines typically give orange-brown, cannabinoids give a red color with the Duquenois-Levine test, and cocaine is tested with Scott reagent.

Question 34Seized Drug Analysis

In a GC-MS analysis, the mass spectrum of an unknown peak shows a molecular ion at m/z 303 and a base peak at m/z 82. Which of the following statements is most accurate?

  1. The molecular ion indicates the compound contains 303 carbon atoms
  2. The molecular ion suggests a molecular weight of 303, and the base peak indicates a prominent fragment Correct answer.
  3. The molecular ion at m/z 303 is always the most intense peak
  4. The base peak represents the molecular ion

Explanation

The molecular ion corresponds to the intact molecule and gives the molecular weight. The base peak is the most intense peak in the spectrum and often arises from a stable fragment. The molecular ion is not necessarily the base peak, and m/z does not directly indicate the number of carbon atoms.

Question 35Seized Drug Analysis

A laboratory uses GC-FID to quantify methamphetamine in seized tablets. The calibration curve is linear from 0.1 to 1.0 mg/mL. A sample is diluted 1:10 and gives a response corresponding to 0.6 mg/mL. What is the concentration of methamphetamine in the original sample?

  1. 60 mg/mL
  2. 0.6 mg/mL
  3. 0.06 mg/mL
  4. 6.0 mg/mL Correct answer.

Explanation

The dilution factor is 10, so the original concentration is the measured concentration multiplied by 10: 0.6 mg/mL × 10 = 6.0 mg/mL. Dividing or not applying the factor would be incorrect.

Question 36Seized Drug Analysis

Which chromatographic technique is most suitable for the analysis of non-volatile and thermally labile drugs?

  1. Gas chromatography-mass spectrometry (GC-MS)
  2. Gas chromatography with flame ionization detection (GC-FID)
  3. Headspace gas chromatography
  4. Liquid chromatography-mass spectrometry (LC-MS) Correct answer.

Explanation

LC-MS operates at or near room temperature and does not require volatilization, making it suitable for non-volatile and thermally labile compounds. GC techniques require volatilization and can degrade such compounds.

Question 37Seized Drug Analysis

In a GC-MS analysis, the presence of a peak with the same retention time and identical mass spectrum as a certified reference standard is generally considered:

  1. A confirmation of identity Correct answer.
  2. Insufficient for identification
  3. A presumptive indication only
  4. Evidence of a mixture

Explanation

Matching both retention time and mass spectrum to a certified reference standard under identical conditions provides highly specific identification, generally accepted as confirmation. Presumptive tests are less specific, and a mixture would show additional peaks.

Question 38Seized Drug Analysis

Which of the following is an advantage of using selected ion monitoring (SIM) over full scan mode in GC-MS?

  1. Simpler spectral interpretation
  2. Wider mass range coverage
  3. Increased sensitivity for target analytes Correct answer.
  4. Identification of unknown compounds

Explanation

SIM monitors only selected ions, increasing the dwell time per ion and reducing noise, which enhances sensitivity for target analytes. Full scan is better for unknown identification and covers a wider mass range.

Question 39Seized Drug Analysis

When quantifying a drug in a complex matrix, what is the purpose of adding a deuterated analog of the analyte as an internal standard?

  1. It closely mimics the analyte's behavior during sample preparation and analysis Correct answer.
  2. It acts as a derivatizing agent
  3. It increases the ionization efficiency of the analyte
  4. It reduces the retention time of the analyte

Explanation

A deuterated analog has nearly identical chemical and physical properties to the analyte, so it experiences similar extraction, derivatization, and ionization efficiencies, compensating for matrix effects and recovery variations. It does not significantly alter ionization efficiency, retention time, or act as a derivatizing agent.

Question 40Seized Drug Analysis

Which of the following statements about the limit of detection (LOD) is correct?

  1. It is the lowest concentration of analyte that can be reliably distinguished from background noise Correct answer.
  2. It is the highest concentration that can be measured without dilution
  3. It is the concentration at which the detector response is linear
  4. It is the lowest concentration that can be accurately quantified

Explanation

LOD is the lowest amount of analyte that can be detected with a defined level of confidence, typically three times the signal-to-noise ratio. The lowest concentration that can be accurately quantified is the limit of quantitation (LOQ).

Question 41Seized Drug Analysis

In the analysis of a seized sample, the presence of a large peak corresponding to a common cutting agent such as lactose would be best identified by:

  1. Its melting point
  2. Its color in the Marquis test
  3. Its Rf value in TLC
  4. Comparison of its mass spectrum and retention time with reference libraries Correct answer.

Explanation

GC-MS with library matching allows identification of both drugs and cutting agents by their mass spectra and retention times. Color tests, TLC, and melting point are less specific or not applicable to complex mixtures.

Question 42Seized Drug Analysis

What is the primary reason for using a guard column in GC analysis of seized drugs?

  1. To reduce the analysis time
  2. To increase the resolution of the analytes
  3. To protect the analytical column from contamination by non-volatile residues Correct answer.
  4. To enhance the detector response

Explanation

A guard column is placed before the analytical column to trap non-volatile impurities and particulates, preventing them from reaching and contaminating the analytical column. It does not significantly affect resolution, speed, or detector response.

Question 43Seized Drug Analysis

In a GC-MS analysis, the mass spectrum of a compound shows a base peak at m/z 58 and a molecular ion at m/z 100. Which of the following statements is true?

  1. The compound has a molecular weight of 58 and a prominent fragment at m/z 100
  2. The base peak is the molecular ion
  3. The molecular ion is the most intense peak
  4. The compound has a molecular weight of 100 and a prominent fragment at m/z 58 Correct answer.

Explanation

The molecular ion at m/z 100 indicates a molecular weight of 100. The base peak at m/z 58 represents the most abundant fragment ion, not the molecular ion.

Question 44Seized Drug Analysis

Which of the following is a key limitation of using retention time alone for peak identification in GC?

  1. Retention time cannot be measured accurately
  2. Retention time is only applicable to mass spectrometry
  3. Retention time is not affected by column temperature
  4. Multiple compounds may have similar retention times under the same conditions Correct answer.

Explanation

Retention time is not unique to a single compound; many compounds can co-elute or have very similar retention times. Therefore, retention time alone is insufficient for identification and must be combined with a specific detection method such as mass spectrometry.

Question 45Seized Drug Analysis

A forensic laboratory needs to determine the enantiomeric composition of a seized methamphetamine sample to infer the synthetic route. Which technique is most appropriate?

  1. Thin-layer chromatography
  2. Chiral GC-MS Correct answer.
  3. Marquis color test
  4. Standard GC-MS with a non-chiral column

Explanation

Enantiomers have identical physical properties and cannot be separated on a standard achiral column. Chiral GC-MS uses a chiral stationary phase to resolve enantiomers, allowing determination of enantiomeric composition, which can provide intelligence on synthetic methods.

Question 46Seized Drug Analysis

In the context of isotope ratio mass spectrometry (IRMS) for drug profiling, what is the primary information obtained?

  1. The enantiomeric purity
  2. The molecular weight of the drug
  3. The isotopic composition of the sample, which can link it to a geographic or synthetic origin Correct answer.
  4. The concentration of the drug

Explanation

IRMS measures the relative abundances of stable isotopes (e.g., 13C/12C, 15N/14N), which can vary with the source of precursors and synthetic pathways, providing intelligence for sample comparison and origin attribution. It does not directly measure molecular weight, concentration, or enantiomeric purity.

Question 47Seized Drug Analysis

A seized sample contains a drug that is thermally labile and non-volatile. Which analytical strategy is most appropriate for its identification and quantification?

  1. GC-MS with derivatization
  2. Direct insertion probe mass spectrometry
  3. LC-MS/MS with a suitable internal standard Correct answer.
  4. GC-FID without derivatization

Explanation

LC-MS/MS operates at or near ambient temperature and does not require volatility, making it suitable for thermally labile and non-volatile compounds. Derivatization may improve GC behavior but can be challenging for highly labile compounds, and direct insertion probe may cause thermal degradation.

Question 48Seized Drug Analysis

In a quantitative GC analysis, the method of standard addition is often used when:

  1. The analyte is volatile
  2. Matrix effects are significant and cannot be compensated by an internal standard Correct answer.
  3. A chiral column is required
  4. The sample is very dilute

Explanation

Standard addition involves adding known amounts of analyte to aliquots of the sample, allowing quantification in the presence of matrix effects that would otherwise cause bias. It is particularly useful when an appropriate internal standard is unavailable or matrix effects are severe.

Question 49Seized Drug Analysis

In the context of seized drug analysis, what does the term 'sampling plan' refer to?

  1. A statistically based procedure to select representative portions from a seizure for analysis Correct answer.
  2. The sequence of solvents used in extraction
  3. The schedule of instrument calibration
  4. The plan for disposing of analyzed samples

Explanation

A sampling plan ensures that the portions selected for analysis are representative of the entire seizure, often using statistical methods to determine sample size and selection. It is not about extraction solvents, calibration schedules, or disposal.

Question 50Seized Drug Analysis

Which reagent produces a blue color with cocaine?

  1. Liebermann reagent
  2. Marquis reagent
  3. Mandelin reagent
  4. Scott reagent Correct answer.

Explanation

The Scott reagent is a cobalt thiocyanate test that gives a blue color with cocaine and other local anesthetics. Marquis, Liebermann, and Mandelin reagents do not produce a blue color with cocaine.