ANALYTICAL METHODS Flashcards
IT IS TRANSMITTED VIA ELECTRONIC WAVES BY FREQUENCY AND WAVELENGTH
ENERGY
RELATIONSHIP BETWEEN WAVELENGTH AND ENERGY
PLANCK’S FORMULA
DISTANCE BETWEEN TWO SUCCESSIVE PEAKS EXPRESSED IN NANOMETERS
WAVELENGTH
400-470NM
VISIBLE SPECTRUM
<400NM
UV LIGHT
> 700NM
INFRARED REGION
IT IS THE NUMBER OF VARIATIONS OF WAVE MOTION PER SECOND
FREQUENCY
RELATIONSHIP OF FREQUENCY AND WAVELENGTH
INVERSELY PROPORTIONAL
MEASUREMENT OF LIGHT IN A NARROWER WAVELENGTH
SPECTROPHOTOMETRIC MEASUREMENT
MEASUREMENT OF LIGHT WITHOUT WAVELENGTH
PHOTOMETRIC MEASUREMENT
MEASURES LIGHT TRANSMITTED TO DETERMINE ITS CONCENTRATION
SPECTROPHOTOMETRY
EMITS RADIATION TAHT CHANGES IN INTENSITY
CONTIMUUM SOURCE
EMITS LIMITED RADIATION AND WAVELNGTH
LINE SOURCE
INTENSE BEAM LIGHT IS DIRECTED THROUGH
MONOCHROMATOR AND SAMPLE
COMMONLY USED LIGHT SOURCE IN VISIBLE AND IR
TUNGSTEN LIGHT BULB
IT GIVES ACCURATE ABSORBANCE MEASUREMENTS AND RESPOSNSE TO CHANGE IN LIGHT INTENSITY
LINEARITY
FACTORS FOR CHOOSING LIGHT SOURCE
- SPECTRUM
- STABILITY
- SOURCE
- RANGE
- TEMPERATURE
ALTERNATIVES FOR COLORIMETRY UV LIGHT
MERCURY ARC
DEUTERIUM LAMP
HYDROGEN LAMP
XENON LAMP
IT MINIMIZES UNWANTED STRAY LIGHT
ENTRANCE SLIT
IT IS A WAVELENGTH OUTSIDE THE BAND CAUSES ABSORBANCE ERROR
STARY LIGHT
MOST COMMON CAUSE OF LOSS OF LINEARUTY AT HIGH ANALYTE CONCENTRATION
STRAY LIGHT
KINDS OF MONOCHROMATORS
PRISMS
DIFFRACTION GRATINGS
FILTER
- GLASS, QUARTZ, SODIUM CHLORIDE
- REFRACTED TO MORE DENSE GLASS
- CAN BE ROTATED
PRISMS
MOST COMMONLY SED AND BETTER RESOLUTION THAN PRISM
DIFFRACTION GRATINGS
–CROWN GLASS
- BENT TO SHARP CORNER
DIFFRACTION GRATINGS
FILTERS HAS SEMI TRANSPARENT SILVER FILMS SUCH AS
MAGNESIUM FLUORIDE
LIGHT BASED ON CONSTRUCTIVE INTERFERENCE OF WAVES
FILTERS
- REFLECTED
- PASS A WIDE BAND OF RADIANT ENERGY
- LOW TRANSMITTANCE
FILTERS
CONTROLS WIDTH OF LIGHT BEAM
ALLOWS ONLY NARROW FRACTION OF SPECTRUM
EXIT SLIT
THE SPECTRAL PURITY OF SPECTROPHOTOMETER IS REFLECTED BY
BANDPASS
REQUIRED BANDPASS FOR ACCURATE ABSORBANCE MEASUREMENT
<1/5
TEH DEGREE OF WAVELENGTH ISOLATION DEPENDS ON
DEVICE
ENTRANCE SLIT
EXIT SLIT
THE RANGE PF WAVELENHTHS BETWEEN POINTS
1/2 PEAK TRANSMITTANCE
BANDPASS
MOST COMMONLY USED CUVETS
ALUMINA SILICA GLASS
CUVET FOR MEASUREMENT OF SOLUTION REQUIRES UV SPECTRUM
QUARTZ/PLASTIC
CUVETS TRANSMIT LIGHT AT >220NM
SILICA OR SOFT GLASS
SOLUTIONS THAT PRODUCES ETCHING
ALKALI SOLUTIONS
DETECTS AND CONVERTS TRANSMITTED LIGHT INTO PHOTOELECTRIC ENERGY
PHOTODETECTOR
- SIMPLIEST, CHEAP, TEMPERATURE SENSITIVE
- SELENIUM PLATE WITH SILVER COVER
- NO EXTERNAL VOLTAGE
BARRIER LAYER CELL/ PHOTO CELL/PHOTOVOLTAIC CELL
IT IS USED IN FILTER PHOTOMETERS WITH WIDE BANDPASS
BARRIER CELL/PHOTOCELL/PHOTOVOLTAIC CELL
- CATHODE AND ANODE
- GLASS CASE
- PHOTOSENSITIVE MATERIAL; GIVES OFF ELECTRONS
- REQUIRES EXTERNAL VOLTAGE
PHOTOTUBE
MOST COMMON TYPE OF DETECTORS
PHOTOMULTIPLIER TUBE
- MEASURES VISIBLE AND UV REGIONS
- EXCELLENT SENSITIVITY AND RAPID
- DETECTS AND AMPLIFIES RADIANT ENERGY
PHOTOMULTIPLIER TUBE
DISADVANTAGE OF PM TUBE
WILL BURN OUT AT ROOM LIGHT
- EXCELLENT LINEARITY
- MULTITUDE OF WAVELENGTHS
- DETECTS LESS AMOUNT OF LIGHT
PHOTODIODE
DISPLAYS OUTPUT OF DETECTION SYSTEM
GALVANOMETER/AMMETER
IT STATES THAT CONCENTRATION OF UNKNOWN SUBSTANCE IS DIRECTLY PROPORTIONAL TO ABSORBED LIGHT AND INVERSELY PROPORTIONAL TO TRANSMITTED LIGHT
BEER’S LAW
IS PROPORTIONAL TO THE INVERSE LOG OF TRANSMITTANCE
ABSORBANCE
IT IS THE RATIO OF RADIANT ENERGY TRANSMITTED OVER INCIDENT RADIANT ENERGY
PERCENT TRANSMITTANCE
INSTRUMENT THAT SPLITS LIGHT INTO 2 COMPONENTS
DOUBLE BEAM SPECTROPHOTOMETER
PASSAGE WAY OF BEAM ACCORDING TO DOUBLE BEAM SPECTROPHOTOMETER
THROUGH THE SAMPLE AND REFERENCE SOLUTION OR BLANK SOLUTION
WHAT DO ADDITIONAL BEAM CORRECTS
LIGHT SOURCE INTENSITY
TYPE OF SAMPLE BEAM
- USES 2 PHOTODETECTORS
- FOR SAMPLE AND REFERENCE BEAM
DOUBLE BEAM IN SPACE
TYPE OF DOUBLE BEAM
- 1 PHOTODETECTOR
- ALTERNATELY ON MONOCHROMATIC LIGHT THROUGH SAMPLE AND REFERENCE CUVET
- CHOPPER
DOUBLE BEAM IN TIME
THE OBSERVED COLOR FROM LIGHT ABSORBED FROM SOLUTION
COMPLEMENTARY COLOR
THEY ARE GREATER IN BLUE REGION THAN IN RED REGION
TURBIDITY
USED TO CHECK WAVELENGTH ACCURACY
DIDYMIUM OR HOLMIUM OXIDE FILTER
VERIFY ABSORBANCE ACCURACY ON LINEARITY
NEUTRAL DENSITY FILTERS AND DICHROMATE SOLUTION