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Questions and Answers

What is the purpose of the exit slit in a light source?

Absorbs excess light energy during transmission

Determines the total range of wavelengths transmitted (correct)

Controls the brightness of the light emitted

Filters out unwanted wavelengths completely

Which light source is appropriate for the UV region?

Tungsten iodide lamp

Xenon discharge lamp

Deuterium lamp (correct)

Tungsten light bulb

What is the main function of a sample cell in spectrophotometry?

To disperse light into its component wavelengths

To reflect light towards the photodetector

To generate light at specific wavelengths

To hold the solution for absorption measurement (correct)

Which of the following is NOT a recommended practice for using a cuvet?

Use a cuvet for multiple types of solutions simultaneously Signup and view all the answers

What is the role of a photodetector in a spectrophotometric system?

To convert light energy into electrical energy Signup and view all the answers

Which light source can be used for infrared measurements?

Merst glower Signup and view all the answers

What potential issue arises if high alkali solutions are left in a cuvet for too long?

Dissolution of cuvet components Signup and view all the answers

Which device allows only the emitted light spectrum of a specific element to strike the photodetector?

Monochromator system Signup and view all the answers

What process involves the separation of molecules based on their size and shape?

Steric/Size Exclusion Signup and view all the answers

What effect does increasing osmolality have on osmotic pressure?

Osmotic pressure increases Signup and view all the answers

What is a key feature of the affinity chromatography technique?

Involves immobilized biochemical ligands Signup and view all the answers

Which type of pipet is characterized by having a continuous etched ring located near the top?

Blow-out pipet Signup and view all the answers

Freezing point osmometry is most commonly used to measure changes in which property of a solution?

Colligative properties Signup and view all the answers

What distinguishes ultracentrifuges from other centrifuge types?

They achieve the highest speeds and are refrigerated Signup and view all the answers

Which pipet is specifically designed to transfer viscous fluids?

Ostwald-Folin pipet Signup and view all the answers

In the context of pipets, what is the function of a 'to deliver' pipet?

It dispenses the exact volume required Signup and view all the answers

Which application would likely utilize mass spectrometry?

Measurement of drugs of abuse in urine Signup and view all the answers

What distinguishes a TC pipet from a TD pipet?

TD pipets deliver a specific volume while TC pipets contain a specific volume Signup and view all the answers

What is a characteristic feature of a Mohr pipet?

Has no graduations up to the tip Signup and view all the answers

What happens to the centrifuge tubes in a swinging bucket type centrifuge during operation?

They are held horizontally during motion Signup and view all the answers

Which type of pipet is known for having the greatest degree of accuracy and precision?

Transfer pipet Signup and view all the answers

What does mass spectrometry primarily rely on for analysis?

The fragmentation and ionization of molecules Signup and view all the answers

Why are ultracentrifuges refrigerated during operation?

To reduce heat produced by high centrifugal forces Signup and view all the answers

What is the primary chemical grade used for reagent preparation as mentioned in the content?

Analytical Reagent Grade Signup and view all the answers

What is a primary role of proteins in the human body?

To provide structural strength and elasticity Signup and view all the answers

Which of the following diseases is related to defective lipid metabolism?

Niemann-Pick Disease Signup and view all the answers

What defines conjugated proteins?

Proteins containing non-protein parts attached Signup and view all the answers

What role do proteins play in gene expression?

They regulate biochemical events Signup and view all the answers

Which statement is true about the structure of proteins?

Proteins are polymers of amino acids linked by peptide bonds Signup and view all the answers

In what circumstance can the charge of a protein be altered?

By changing the pH of the surroundings Signup and view all the answers

What type of proteins are involved in immune defense?

Defensive proteins Signup and view all the answers

What is the purpose of interference experiments in clinical chemistry?

To measure systematic errors caused by substances other than analytes. Signup and view all the answers

Which of these proteins are classified as digestive enzymes?

Chymotrypsin and pepsin Signup and view all the answers

Which of the following statements best describes Beer’s Law?

The absorbance is directly proportional to the concentration of a substance. Signup and view all the answers

What is Point of Care Testing (POCT)?

Testing performed outside the lab, usually by nonlaboratory personnel. Signup and view all the answers

What does the physiologic limit (absurd value) help detect?

Method problems or incorrect data recording. Signup and view all the answers

Which component of the spectrophotometer minimizes stray light?

Entrance slit. Signup and view all the answers

How does the Formula A = abc relate to absorbance?

It shows the relationship between absorbance and the concentration of the analyte. Signup and view all the answers

What is the significance of recovery experiments in clinical chemistry?

They confirm whether a method measures all analytes accurately. Signup and view all the answers

What can cause loss of linearity in spectrophotometric measurements?

Presence of stray light within the monochromator. Signup and view all the answers

What is the primary characteristic of a continuous flow analyzer?

Samples flow through a common reaction vessel. Signup and view all the answers

Which statement best describes random access testing?

Any test can be performed on any sample in any sequence. Signup and view all the answers

In a centrifugal analyzer, what is the primary role of centrifugation?

To transfer the specimen and reagents. Signup and view all the answers

What is a defining feature of an open reagent system?

Users can utilize reagents from different manufacturers. Signup and view all the answers

Which approach to automation allows for the analysis of multiple tests at the same time?

Parallel testing Signup and view all the answers

What role do air bubbles play in a continuous flow analyzer?

They serve as a cleaning medium and ensure proper flow. Signup and view all the answers

What is the main disadvantage of batch testing compared to other automation methods?

It requires simultaneous loading of all samples. Signup and view all the answers

Which statement about the relationship between heating baths and reaction temperature is correct?

They help maintain the required temperature for color development. Signup and view all the answers

Study Notes

Quality Control

A system for ensuring accuracy and precision in laboratory measurements, including quality control reagents in every series of measurements.
Process to ensure analytical results are correct by testing known samples.
Monitors analytical processes and detects errors.
Assesses the "health" of an analytical method.

Quality Control Parameters

Sensitivity
Specificity
Accuracy
Precision/Reproducibility
Practicability
Reliability
Diagnostic sensitivity
Diagnostic specificity

Quality Control Types

Built-in Controls: Integrated into test kits; used to confirm that diluents and active ingredients are functional, but not a confirmation of sample application or kit performance. Validates kit performance, not the entire testing process.
Traditional Controls: Mimics patient samples, to evaluate the integrity of the entire testing process. Often included within a testing kit. Can also be commercially prepared.

Intralab (Internal QC)

Involves analyzing control samples alongside patient samples.
Monitors accuracy and precision of analytical methods.
Detects random and systematic errors.

Interlab (External QC)

Proficiency testing program using samples of unknown concentrations.
Maintains long-term accuracy of analytical methods.

Sources of Quality Control

Human-based
Bovine-based

Objectives of Quality Control

Validating the reliability of the test system
Verifying instrument and reagent conditions
Evaluating operator performance
Assessing environmental conditions impacting results
Checking machine and reagent stability.
Detecting and monitoring any technical errors

Ideal QC Material Characteristics

Resembles human samples
Inexpensive and stable for extended periods
Free of communicable diseases
No matrix effects (sample interference)
Known analyte concentration
Convenient and easy dispensing/storage

Coefficient of Variation (CV)

The standard deviation expressed as a percentage of the mean.
Used to monitor precision.
Used to compare methods.
Ideally should be less than 5%.

Analytical Variations/Errors

Systematic Error: Predictable errors, occurring in a pattern.
Random Error: Unpredictable, imprecise errors, based on imprecision.

Random Error Types

Mislabeling
Pipetting errors
Improper mixing of sample and reagents
Voltage fluctuations
Temperature fluctuations
Dirty optics

Systematic Error Types

Improper calibration
Deterioration (of reagents)
Contamination (of solutions)
Sample instability (unstable reagent blanks)
Changes in standard materials
Broken ion selective electrodes
Low lamp power
Incorrect instrument settings
Incorrect sample and reagent volume
Procedure errors

Quantitative Control Chart

Plots control material values, calculated mean and +/- 1, 2, and 3 standard deviations (SD).

Quality Control Chart

Gaussian Curve (Bell-Shaped Curve): Data is centered around the mean, with most elements close to the mean (accuracy). A shift in the mean indicates an accuracy problem, while increased SD points to a precision problem.
Shewhart Levey-Jennings Chart: Commonly used chart for continuous monitoring and detecting patterns or errors in analytical processes.
Control Rules: Standards for ruling out any irregularities. Includes 13s, 22s and 41s, these rules detect random and systematic errors.
Youden Plot: Compares results from high and low control sera, from different laboratories. Detects problems in different labs operating conditions.

Standard Deviation (SD)

Measure of variability used in the laboratory.

Delta Check

Used to compare present results with past results.

Interference and Recovery Experiments

Used to measure systematic errors or inaccuracies in an assay.

Point of Care Testing (POCT)

Analytical tests performed outside the laboratory, typically by non-laboratory personnel.
Examples include blood glucose meters.

Analytical Techniques and Instrumentation

Photometry: Measures the absorbance or transmission of light through a sample.
Spectrophotometry Single beam and double beam types Using light of selected wavelength Components: Source of light, monochrometer (isolates specific wavelengths), cuvette for sample, and detector(converts light to electrical energy).
Spectrophotometry: The quantitative measure of light absorbed or transmitted by a sample dissolved in a solution.

Quality Control (QC) Chart Elements

Gaussian Curve (Bell-Shaped Curve): Data elements are centered around the mean; elements close-to the mean -accuracy.
Deviation (SD): Increased SD -precision problem.
Mean/ Average: Increased or decreased mean-accuracy problem.
Rules: 13s, 22s, 41s, R4s, and 10x.

Other Analytical Methods

Turbidimetry: Measures the reduction in light transmission caused by particles in the liquid sample;
Nephelometry: Measures the scattering of light by particles in a liquid sample.
Chemiluminescence: Measures the light emitted from a chemical reaction.

General/Clinical Chemistry

Cuolometry: Measurement of the amount of electricity in coulombs at a fixed potential.
Voltammetry: Measurement of current at varying potential.
Electrophoresis: Separates charged molecules in an electrical field, based on size and charge.
Chromatography: Separates complex mixtures based on interactions between individual compounds and the stationary phase of the system.
- Gas Chromatography
- High-Performance Liquid Chromatography (HPLC)

Other Methods (e.g., Capillary Electrophoresis, Mass Spectrometry)

Briefly described

Specimen Collection and Handling

Describe common specimen collection practices (e.g., blood draws), preparation, and handling details.

Patient Preparation

Describe factors affecting test results (e.g., exercise, fasting, posture).

Capillary Puncture (Skin Puncture)

Discuss the procedure, considerations and precautions.

Anticoagulants

Types (e.g., oxalate, citrate, EDTA), their roles (e.g., combine with Calcium).

Other important elements (osmometry, hormones)

Described briefly, and other important aspects of clinical chemistry.

Automated Testing

Approaches (e.g., Continuous Flow, Centrifugal),
Terminologies (e.g., sequential testing, batch testing).

Other tests and procedures

Describe different types of blood tests, urine tests, and other relevant methods.

Reference Ranges

Provide reference values for specific components/tests.

Diseases

Describe conditions/diseases related to the mentioned elements and procedures.

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