Questions
3-4 questions in university semester exams
Difficulty
Medium-Hard
Importance
High yield for clinical and core instrumentation papers
Overview
Laboratory instrumentation covers the fundamental principles and operational mechanisms of analytical devices used in clinical and industrial settings. Mastering these techniques is essential for accurate diagnostics and material characterization, forming the backbone of practical laboratory assessments in health and engineering sciences.
Spectrophotometry and Electrophoresis
Spectrophotometry quantifies substances by measuring light absorbance based on the Beer-Lambert Law, while electrophoresis separates charged particles in a matrix under an electric field. These are the two most frequently tested diagnostic techniques in clinical biochemistry.
- Beer-Lambert Law: A = εcl
- Visible range: 400-700 nm
- Electrophoresis buffer maintains pH
- Separation based on charge-to-mass ratio
- Supporting media: Agarose or Polyacrylamide
Immunoassay Techniques (RIA, ELISA, Chemiluminescence)
These techniques rely on specific antigen-antibody binding reactions to detect trace amounts of analytes like hormones and viral markers. ELISA uses enzymatic signals, while RIA utilizes radioactive isotopes and Chemiluminescence produces light via chemical reactions.
- ELISA: Enzyme-linked immunosorbent assay
- RIA: Radioimmunoassay using isotope tracers
- Chemiluminescence: Light emission from excited states
- High sensitivity for hormone assays
- Requires stringent washing steps to prevent noise
High-Performance Liquid Chromatography (HPLC)
HPLC is a robust analytical method used to separate, identify, and quantify each component in a mixture by forcing the mobile phase through a stationary phase column. It is the gold standard for purity analysis in pharmaceuticals.
- High-pressure pump system
- Stationary phase: Silica or modified silica
- Retention time (Rt) is the identification metric
- Detector types: UV-Vis, PDA, or Mass Spectrometry
- Normal phase vs. Reverse phase chromatography
Ion-Selective Electrodes & ABG Analyzers
Ion-Selective Electrodes (ISEs) provide real-time concentration measurements of specific ions in solution, which is the operational principle behind Arterial Blood Gas (ABG) analyzers. These tools are critical for monitoring acid-base balance in critical care.
- Nernst Equation: E = E0 + (RT/zF) ln a
- Potentiometric measurement technique
- Glass membrane for pH electrodes
- Direct measurement of pO2, pCO2, and pH
- Requires frequent calibration with standard buffers
Formula Sheet
Absorbance A = log(I0/It) = εcl
Nernst Equation: E = E0 + 0.0592/n * log[ion]
Retention Factor k = (tR - tM) / tM
Exam Tip
Always state the underlying physical principle—like the Nernst Equation or Beer-Lambert Law—in the first sentence of your long-answer responses to ensure maximum marks.
Common Mistakes
- Confusing the roles of mobile and stationary phases in HPLC chromatography.
- Neglecting the log-linear relationship in the Beer-Lambert Law during numerical problems.
- Failing to mention specific detectors like UV-Vis when asked about the principle of a device.
More Revision Notes
Ready to test yourself?
Play topic-wise Laboratory Instrumentation & Analytical Techniques questions in Aspirant Arcade — gamified MCQ practice.
Download Free