Immunoassays in Forensic Science: ELISA, RIA, FPIA, Lateral Flow and Case Analysis (UGC-NET Unit II)
Published:
Questions
30
Duration
30 min
Faculty-reviewed
0
Updated
17 May 2026
About this mock
UGC-NET Forensic Science Paper II Unit II hard-band drill on advanced immunoassay theory and forensic casework: the molecular basis of antigen-antibody binding, monoclonal versus polyclonal antibody selection, the four major label chemistries (radioactive RIA, enzymatic ELISA and EMIT, fluorescent FPIA, chemiluminescent CLIA), competitive and sandwich formats, sensitivity and specificity trade-offs, and the cross-reactivity matrices that govern false positives in drugs-of-abuse screening. Each question walks the student through a casework scenario, a SAMHSA Mandatory Guidelines cut-off, or a cross-reacting compound (poppy-seed morphine for opiates, dextromethorphan for PCP, Vicks l-methamphetamine for amphetamine, NSAIDs and pseudoephedrine for structural mimics) and tests the confirmatory analysis requirement under SAMHSA, ASB / SOFT, and the NDPS Act analytical chain.
Designed for UGC-NET Paper II aspirants, NFSU MSc Forensic Science students, and FACT candidates revising serology and toxicology immunoassays. Hard-band distractors differ from the correct answer on a single subsection, a single numerical cut-off, or a single mechanistic step, so the student must know the precise SAMHSA threshold, the specific antibody cross-reactivity, and the right confirmatory technique rather than the broad concept.
Topics covered:
- Antigen-antibody binding kinetics and antibody selection for forensic immunoassays
- Label chemistries: radioactive (RIA), enzymatic (ELISA, EMIT), fluorescent (FPIA), chemiluminescent (CLIA)
- Competitive versus sandwich formats and when each applies
- SAMHSA Mandatory Guidelines cut-offs for cannabinoids, opiates, amphetamines, cocaine and PCP
- Cross-reactivity matrices and structural-mimic false positives in drugs-of-abuse screening
- Forensic biological assays: Hexagon OBTI, ABAcard p30, RSID-Saliva, ABAcard HemaTrace
- Species identification by precipitin and ELISA with anti-human antibodies
- Confirmatory testing under SAMHSA, ASB / SOFT guidelines, and the NDPS Act analytical chain
Calibrated for serious UGC-NET preparation in the run-up to the next cycle and aligned with the current Paper II Unit II syllabus references to immunological techniques, serology, and forensic toxicology.
Allow 30 minutes.
Sources & references
Questions in this mock are written and verified against the following sources. Citations are recorded per question and shown in the explanation after submission.
- cited in 3 questions
Moeller K.E., Kissack J.C., Atayee R.S., Lee K.C., Clinical Interpretation of Urine Drug Tests, Mayo Clin Proc 2017; 92(5):774
Methamphetamine cross-reactivity and the Vicks-inhaler licit-use defence; chiral GC-MS resolution
Open source - cited in 2 questions
SAMHSA Mandatory Guidelines for Federal Workplace Drug Testing Programs (Urine), 82 FR 7920
Section 3.5: opiate confirmation cut-off 2000 ng/mL; separate 6-acetylmorphine cut-off 10 ng/mL for heroin proof
Open source - cited in 1 question
Old J.B., Schweers B.A., Boonlayangoor P.W., Reich K.A., Developmental validation of RSID-Saliva, J Forensic Sci 2009; 54:866
Validation of Rapid Stain Identification of Saliva (RSID-Saliva) targeting human salivary alpha-amylase AMY1
Open source - cited in 1 question
ASB Standard 036, Standard for Method Validation in Forensic Toxicology; SOFT/AAFS Forensic Toxicology Laboratory Guidelines 2006
Confirmation requirements: GC-MS or LC-MS/MS, retention-time and ion-ratio criteria, reference-standard traceability
Open source - cited in 1 question
NDPS Act 1985 and Narcotics Control Bureau Standing Order 1/89; DFSS, MHA, Forensic Toxicology Quality Manual
Indian analytical framework for drugs-of-abuse casework; chain of custody and confirmation requirements
Open source - cited in 1 question
Smith M.L., Cone E.J., Drugs of Abuse Testing: Interpretation and Pitfalls, in Levine B. (ed.), Principles of Forensic Toxicology, 5th Edition
Cross-reactivity of opiate immunoassays and the oxycodone false-negative problem
- cited in 1 question
Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 6th Edition
Immunochemical Techniques, competitive versus sandwich ELISA, format selection by analyte size
- cited in 1 question
SAMHSA Mandatory Guidelines for Federal Workplace Drug Testing Programs (Oral Fluid), 84 FR 57554 (2019)
Oral-fluid initial-test and confirmatory cut-offs; DRUID project comparators
Open source - cited in 1 question
Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 6th Edition (Rifai N, ed.)
Chapter on Immunochemical Techniques, antibody affinity and immunoassay design
- cited in 1 question
NDPS Act, 1985, Section 52A, read with Union of India v. Mohanlal, (2016) 3 SCC 379
Mandatory sampling procedure before Magistrate; FSL analytical chain through immunoassay screen and GC-MS confirmation
Open source - cited in 1 question
Johnston E., Ames C.E., Dagnall K.E., Foster J., Daniel B.E., Comparison of presumptive blood test kits including Hexagon OBTI, J Forensic Sci 2008; 53(3):687
Validation of Hexagon OBTI human-haemoglobin lateral-flow immunoassay for forensic stain identification
Open source - cited in 1 question
Yalow R.S., Berson S.A., Immunoassay of endogenous plasma insulin in man, J Clin Invest 1960; 39:1157
Foundational paper on radioimmunoassay; competitive heterogeneous format with 125I tracer
Open source - cited in 1 question
SAMHSA Mandatory Guidelines for Federal Workplace Drug Testing Programs (Urine), revised effective 1998 and consolidated in 82 FR 7920
Section 3.4 to 3.5: opiate cut-off raised to 2000 ng/mL; separate 6-acetylmorphine cut-off at 10 ng/mL
Open source - cited in 1 question
Cone E.J., Welch P., Mitchell J.M., Paul B.D., Forensic drug testing for opiates: poppy-seed urine, J Anal Toxicol 1991; 15:1
Computation of morphine-equivalent immunoassay signal from cross-reactivity matrix; SAMHSA cut-off implications
- cited in 1 question
Hochmeister M.N., Budowle B., Rudin O. et al., Evaluation of prostate-specific antigen (PSA) membrane test assays for the forensic identification of seminal fluid, J Forensic Sci 1999; 44:1057
Validation of ABAcard p30 lateral-flow PSA test for forensic seminal-fluid identification
Open source - cited in 1 question
Huestis M.A., Mitchell J.M., Cone E.J., Detection times of marijuana metabolites in urine by immunoassay and GC-MS, J Anal Toxicol 1995; 19:443
Window of detection for THC-COOH in urine in chronic heavy users versus occasional users
- cited in 1 question
SAMHSA Mandatory Guidelines for Federal Workplace Drug Testing Programs (Urine), Final Rule, 82 FR 7920
Section 3.4 to 3.5: Validity testing and initial test analytes; cross-reactivity documentation
Open source - cited in 1 question
Directorate of Forensic Science Services (DFSS), MHA, Quality Manual for Toxicology Section, CFSLs
Two-tier workflow for narcotics analysis: immunoassay screening followed by GC-MS or LC-MS/MS confirmation
Open source - cited in 1 question
Weeks I., Beheshti I., McCapra F., Campbell A.K., Woodhead J.S., Acridinium esters as high-specific-activity labels in immunoassay, Clin Chem 1983; 29:1474
Foundational paper on acridinium ester chemiluminescence in immunoassay
- cited in 1 question
SD Bioline Multi-Drug Urine Test Cassette package insert (Abbott Diagnostics, Standard Diagnostics)
Competitive lateral-flow read interpretation: test line present below cut-off, absent at or above cut-off
- cited in 1 question
Posthuma-Trumpie G.A., Korf J., van Amerongen A., Lateral-flow (immuno)assay: its strengths, weaknesses, opportunities, Anal Bioanal Chem 2009; 393:569
Operational comparison of lateral-flow immunoassays and plate ELISA in diagnostic and forensic biology workflows
Open source - cited in 1 question
Rubenstein K.E., Schneider R.S., Ullman E.F., Homogeneous enzyme immunoassay, Biochem Biophys Res Commun 1972; 47:846
Foundational EMIT paper, glucose-6-phosphate dehydrogenase conjugate format
- cited in 1 question
Schweers B.A., Old J., Boonlayangoor P.W., Reich K.A., Developmental validation of a fluorescence-detected immunoassay, J Forensic Sci 2008; 53(1):104
Lateral-flow sandwich immunoassay limitations, high-dose hook effect at saturating antigen concentration
Open source - cited in 1 question
Levine B. (ed.), Principles of Forensic Toxicology, 5th Edition, AACC Press
Chapter on Drugs-of-Abuse Testing: design philosophy of screening immunoassays and the role of mass-spectrometric confirmation
- cited in 1 question
Dandliker W.B., Feigen G.A., Quantification of the antigen-antibody reaction by the polarisation of fluorescence, Biochem Biophys Res Commun 1961; 5:299
Foundational fluorescence polarisation immunoassay paper; basis of the Abbott TDx platform
- cited in 1 question
Saferstein R., Criminalistics: An Introduction to Forensic Science, 12th Edition
Chapter on Forensic Serology, Uhlenhuth precipitin test and species identification by ELISA
- cited in 1 question
National Institute of Biologicals (NIB), Noida, official mandate, Ministry of Health and Family Welfare
National reference laboratory for vaccines, sera, and immunoassay reagents
Open source
How our mocks are built
Questions are written and edited by the ForensicSpot team and cited from peer-reviewed forensic textbooks, official syllabi and primary case law. Each one is verified before publishing. Detailed explanations show after you submit, so the test stays a real test. See a mistake? Tell us.
Common questions
What does the Immunoassays in Forensic Science: ELISA, RIA, FPIA, Lateral Flow and Case Analysis (UGC-NET Unit II) mock cover?+
UGC-NET Forensic Science Paper II Unit II hard-band drill on advanced immunoassay theory and forensic casework: the molecular basis of antigen-antibody binding, monoclonal versus polyclonal antibody selection, the four major label chemistries (radioactive RIA, enzymatic ELISA and EMIT, fluorescent FPIA, chemiluminescent CLIA), competitive and sandwich formats, sensitivity and specificity trade-offs, and the cross-reactivity matrices that govern false positives in drugs-of-abuse screening. Each q
How many questions and how long is the test?+
30 multiple-choice questions, 30 minutes total. Difficulty: hard. Tier: Premium.
Who is this mock for?+
Forensic science students and aspirants who want timed, exam-style practice with explanations and verified source citations on NET. Useful for postgraduate entrance preparation and for BSc / MSc forensic students testing their recall under time.
Are the questions reviewed?+
Each question carries a verified source citation. Faculty review for individual questions is in progress.
Do I need an account to take this mock?+
Yes, a free ForensicSpot account is required to start a timed attempt — this lets you save progress, see per-question explanations after submission, and track your topic-level performance over time.