Analytical Method Flashcards
Distance between two successive peaks; expressed in nanometers
Wavelength
Range of visible light
400-700 nm
UV
Infrared
> 700 nm
Relationship between wavelength and energy is describe in
Planck’s formula
Number of vibrations of wave motion per second
Frequency
Note: Wavelength is INVERSELY proportional to frequency and energy.
⬆️ frequency = ⬇️ wavelength
Remeber this!
Wavelength in nanometers at peak transmittance
Nominal wavelength
Is the wavelength indicated on the control dial is the actual wavelength of light passed by the monochromator
Wavelength accuracy
Used to check for wavelength accuracy
Holmium oxide and didymium
Used to check for absorbance accuracy
Neutral density filters and dichromate solution
Is transmitted via electromagnetic waves that are characterized by their frequency and wavelength
Energy
Most common analytical method used in clinical chemistry
Colorimetry
Involves measurement pf the light transmitted by a solution to determine the concentration of the light absorbing substances in the solution
Spectrophotometry
Simplest type of absorption spectrometer; one measurement at a time at one specified wavelength
Single beam spectrophotometer
Instrument that splits the monochromatic light into two components
Double beam spectrophotometer
Note: 2 Types of Double-beam Spectro
Double beam in space - 2 photodetectors
Double beam in time - uses a rotator or chopper
Remember this!
Provides polychromatoc light and must generate sufficient radial energy or power to measure the analyte of interest
Light source
Type of a light source where it emits radiation that changes in intensity
Continuum souce
Type of light source wherein it emits limited radiation and wavelength
Line source
Most commonly used light souce in the visible and near infrared region
Tungsten light bulb
Light source for UV radiation
Deuterium lamp
Light source that produces a continous source of radiatoon which covers goth UV and the visible range
Xenon lamp
Minimizes unwanted or stray light
Entrance slit
Any wavelength outside the band
Stray light
Isolates specific or individual wavelength
Monochromator
Wedge-shaped piece of glass, quartz or sodium chloride
Prism
Most commonly used monochromator
Diffraction gratings
Simple, least expensive; based on tue principle pf constructive interference of waves
Filters
Controls the width of light beam (bandpass)
Exit slit
Total range of wavelength transmitted
Bandpass
Note:
The narrower the bandpass, the greater the resolution
Remember this!
Also known as the sample cell; it holds the solution
Cuvet
Most commonly used cuvet
Alumina silica glass
Cuvet for UV radiation
Quartz
It detects and converts transmitted light into photoelectric energy
Photodetector
Simplest photodetector; used in filter photometers; used for detecting and measuring radiation on the visible region; composed of selenium on a plate of iron covered with transparent later of silver
Barrier layer cell/ Photocell/ Photovoltaic cell
Contains cathode and anode; gives off electron when light energy strikes it
Phototube
Most commonly used detector; most sensitive
Photomultiplier tube (PMT)
Photodetector with excellent linearity
Photodiode