CC lec prelim analytical methods

Wavelength

Distance between two successive peaks, expressed in nanometers (nm).

Frequency

Number of vibrations of wave motion per second.

Planck's Formula

Describes the inverse relationship between wavelength, frequency, and energy (E).

Visible Spectrum

The region of the electromagnetic spectrum spanning 400 to 700 nm.

Ultraviolet Region (UV)

The region of the electromagnetic spectrum with wavelengths less than 400 nm.

Infrared Region

The region of the electromagnetic spectrum with wavelengths greater than 700 nm.

Spectrophotometry

Measurement of light transmitted by a solution to determine the concentration of light-absorbing substances.

Single-beam Spectrophotometer

Simplest type of spectrophotometer designed to make one measurement at a time at one specified wavelength.

Double-beam in Space

Spectrophotometer design that splits light and uses two photodetectors to measure sample and reference simultaneously.

Double-beam in Time

Spectrophotometer design that splits light but uses only one photodetector with a chopper to measure over time.

Continuum Source

Light source that emits radiation that changes continuously in intensity (e.g., tungsten, deuterium, xenon).

Tungsten Light Bulb

Most commonly used light source for visible and near-infrared spectrophotometry.

Deuterium Lamp

Light source routinely used to provide UV radiation down to 165 nm.

Xenon Discharge Lamp

Light source that covers both UV and visible light spectra.

Line Source

Light source emitting limited radiation and wavelength, such as a hollow cathode lamp or laser.

Entrance Slit

Component that minimizes unwanted stray light and prevents scattered light from entering the monochromator.

Stray Light

Wavelengths outside the transmitted band that do not originate from the light source and cause absorbance errors.

Diffraction Gratings

Most commonly used monochromator, made by cutting grooves or slits into an aluminized flat piece of crown glass.

Exit Slit

Controls the width of the light beam (bandpass), allowing only a narrow fraction of the spectrum to reach the cuvette.

Bandpass

The total range of wavelengths transmitted by the exit slit of a monochromator.

Alumina Silica Glass Cuvette

Most commonly used cuvette type, suitable for wavelengths from 350 nm to 2000 nm.

Quartz / Plastic Cuvette

Cuvette type required for solutions measured in the ultraviolet spectrum.

Photodetector

Component that detects transmitted light and converts it into photoelectric energy.

Photomultiplier Tube (PMT)

The most sensitive photodetector type, which amplifies the initial electronic signal.

Photodiode

Photodetector that is not as sensitive as PMT but features excellent measurement linearity.

Didymium / Holmium Oxide Filter

Filter used to monitor and check the wavelength accuracy of a spectrophotometer.

Neutral Density Filter / Dichromate

Used to verify the photometric linearity of a spectrophotometer.

Beer's Law

Concentration of an unknown is directly proportional to absorbed light and inversely proportional to transmitted light.

Reagent Blank

Blanking technique that subtracts the inherent color of the reagents from each unknown reading.

Sample Blank

Blanking technique that corrects for optical interferences by measuring sample and reagent without the end product.

Flame Emission Photometry

Measures light emitted by excited electrons returning to ground state using a flame as both source and cuvette.

Indirect Internal Standard Method

Flame photometry method utilizing lithium or cesium as internal standards to minimize variations.

Atomic Absorption Spectrophotometry

Measures light absorbed by ground-state, unexcited atoms dissociated from chemical bonds by heat.

Hollow-cathode Lamp

The specialized light source used in atomic absorption spectrophotometry.

Turbidimetry

Determines the amount of light blocked by particulate matter suspended in a turbid solution.

Nephelometry

Determines the amount of scattered light (at an angle) by particulate matter in a turbid solution.

Fluorometry

Measures light emitted by a molecule after excitation over a zero background, using primary and secondary filters.

Chemiluminescence

Chemical reaction yielding an electronically excited compound that emits light as it returns to its ground state.

Freezing Point Depression Osmometry

Measures osmolality by supercooling a solution and detecting the stable temperature depression caused by solute particles.

Thermistor

The temperature-sensing device used in osmometry to detect the exact freezing point of the sample.

Electrophoresis

Migration and separation of charged particles (such as proteins) in an electric field based on charge densities.

Cellulose Acetate

Electrophoretic support medium that separates proteins primarily by molecular size.

Agarose Gel

Electrophoretic support medium separating by electrical charge that does not bind protein.

Polyacrylamide Gel

Electrophoretic medium separating by charge and size, dividing proteins into 20 fractions; used to study isoenzymes.

Densitometry

Measures the absorbance of electrophoresis stains to scan and quantitate individual protein bands.

Isoelectric Focusing

Separates molecules by migrating them through a pH gradient until they reach their neutral charge point.

Capillary Electrophoresis

Separation of molecules inside a fused silica capillary driven by electro-osmotic flow.

Potentiometry

Electrochemistry measuring electrical potential differences (voltage) between a reference and measuring electrode.

Nernst Equation

Mathematical equation used in potentiometry to calculate ion concentration from measured potential difference.

Saturated Calomel Electrode

Reference electrode consisting of mercury in contact with a solution saturated with mercurous chloride.

Silver-silver Chloride Electrode

Reference electrode ideal for high temperatures above 60 degrees Celsius.

Severinghaus Electrode

Modified pH electrode contained in a sodium bicarbonate jacket with a gas-permeable membrane to measure pCO2.

Direct ISE

Ion-selective electrode assay performing measurements directly on undiluted patient serum.

Indirect ISE

Ion-selective electrode assay requiring dilution of patient serum (usually 1:16 to 1:34) before measurement.

Coulometry

Electrochemistry measuring the quantity of electricity at a fixed potential, following Faraday's Law.

Amperometry

Electrochemistry measuring current flow produced by an oxidation-reduction reaction at a constant voltage.

Clark Electrode

Amperometric polarographic electrode used to measure partial pressure of oxygen (pO2).

Voltametry

Measures current after applying potential, allowing sample preconcentration to detect minimal analyte levels.

Chromatography

Separation of soluble components using physical-chemical differences between a mobile and stationary phase.

Retention Time

The time required for an analyte to travel through a chromatographic column, used for qualitative identification.

Area Under the Peak

The chromatographic metric used to measure and quantitate the concentration of an analyte.

Gas Chromatography (GC)

Separation of volatile compounds using inert carrier gases (helium, nitrogen, hydrogen, argon) as the mobile phase.

Reversed-Phase HPLC

Liquid chromatography style with a nonpolar stationary phase (C-18) and a polar mobile phase.

Size Exclusion Chromatography

Separates molecules based on size and shape, where larger molecules elute rapidly from the column first.

Mass Spectrometry (MS)

Fragments and ionizes molecules, plotting components by mass-to-charge (m/z) ratio and relative abundance.

Proteomics

Study of proteins to identify potential disease biomarkers for clinical diagnosis.

Metabolomics

Study measuring the concentration of very small metabolites using separation and mass-to-charge ratios.

MALDI-TOF MS

Separates ionized samples through a time-of-flight tube to measure travel time to the detector.

Point-of-Care Testing (POCT)

Near-patient, bedside, or decentralized clinical testing performed outside the lab, typically by non-laboratorians.

Continuous Flow Analyzer

Automated system pumping liquids through continuous tubing, running sequential panels on all samples sharing a pathway.

Centrifugal Analyzer

Automated system using centrifugal force to spin specimens and reagents into separate matched perimeter cuvettes.

Discrete Analyzer

Most popular and versatile automated system, using random access to run only requested tests one-at-a-time per sample.

Open Reagent System

Automated analyzer allowing the use of reagents from third-party manufacturers.

Closed Reagent System

Automated analyzer restricting the operator to use only the manufacturer's proprietary reagents.

Master Lot

Calibration information embedded in barcoded reagent labels, containing curves, expectancies, and tolerances.

Middleware

Central software hub consolidating data and interactions from all instruments onto a single technologist display.

Physical Workcell

A cluster of clinical laboratory devices physically connected by a track with a single sample loading area.

Virtual Workcell

A cluster of clinical laboratory devices connected digitally via middleware instead of fingerprints physically by a track.