Analytical Methods

Detection Levels

Quick Tests

element

Flame color

Titration Setup

pipette

titrationsolution

Colorimetry

warning zone

nitrate zone

Air pollution measurement

Outdoor / indoor air pollution measurement

Outdoor measurement: Emissions – from sources

Imissions - in outdoor air

Emissions + imissions: Mass concentration.

Emissions: Mass flow

What is necessary to know:

volume, flow and gas velocity,

temperature, pressure

Emission measurement:

Emission limit: concentration (mg/m3), ppm, mass flow (kg/h)

Particulate matter measurement:

• Gravimetric analysis

• Radiometric metod

• Photometric metod

Toxic matter estimation:

• Chemical analysis

Common estimation of solid chemical elements:

• Atomic absorption spectrometry

• Neutron Activation Analysis

• Roentgen fluorescent analysis

• Mass Spectrometry

Estimation of gas‘s pollutants:

• Infrared spectrometry – SO2, CO, NO, CO2, HCl, NH3, H2O

• Ultraviolet spectrophotometry – SO2, NO, Cl2, NO2, O3

• Potentiometry – HF, HCl

• Colorimetry – H2S

• Ionisation in flame - CxHy

• Catalytic burning - CxHy

• Chemiluminisce – NO

• Paramagnetic princip – O2

• Photometric method – SO2, NO

Imission measurement:

Imission limits (mass concentration)

AIM stations (net)

Particle aerosol: Radiometry

SO2: UV – fluorescence

NOx: Chemiluminiscence

O3: UV spectrometry

Cx Hy: Gas chromatografy

CO Infrared spectrometry

TX/RX 1

TX/RX 2

Classification of analysators

1) Physical princip

• Density• Sound velocity• Heat conductivity• Viscosity• Diffusion• Absorption of radiation• Light refraction• Magnetic susceptibility• Ionisation• Elektrolytic conductivity

2) Physical – chemical princip

• Temperature measurement through chemical reaction • Current measurement at electrochemical cell • Voltage measurement between two electrode immersed into analysed

fluid

3) Chemical princip• Difference of values before and after a chemical reaction

Obr.3 Time progression of measured value andmeasuring device reading

Obr.5 Absorption/concentration dependence (Lambert-Beer law) c – concentration of absorbing matter, A – absorption of light–

dependance on λ, ε - absorption coefficient of the absorber, l - path length

I = I0 e-εcl

A = (I0-I)/ I0

Obr.6 Modification of absorption. 1 – exponencial dependence(Lambert-Beer law), 2 – if filter is wide, 3 – if solid particles are present

Obr.7 Setup of photometric analysator. 1- source ofradiation, 2-filter, 3-measuring cell, 4-detector, 5-signal

processing

Obr.9 Two beam photometric analysator with commondetector. 3- filter for λ, 7-rotating shutter, 4-measuring cell, 8-

reference cell

Obr.11 Photometric analysator with switching of thewavelength

Obr.12 Absorption for heterochromatic arrangement ofpfotometric analysator. λ1-created by interf. filter If1, dark area –

absorbance of the measured sample, A,B- low concentration of measured sample, C,D-higher concentration

Obr.14 Light dispersion on particles–nephelometry

Obr.15 Light absorption at particles–turbidimetry

Obr.16 Absorption spectra of some gases in UV region

Obr.21 Absorptionspectra of some

gases in infrared region

Obr.23 Infrared analysator Hartmann & Braun URAS21 – source of infrared radiation, 2 – reflector, 3 – rotating shutter, 4 –

measuring cell, 5 – reference cell, 6 – detector, 7 – membrane of pressure sensor, 8 – solid stable electrode, 9 – amplifier

Obr.24 Infrared analysator Brüel a Kjær1 – source of infrared radiation, 2 – detector, 3 – rotating shutter– modulator, 4 – carousel with filters, 5 – infrered transparent window, 6 – měřící kyveta, 7 – pressure sensor – micropfone, 8 – valve, 9 – measuring gas supply, 10 –

filter

Obr.50 Fluorescent analysator SO21 – Hg gas tube, pulsed supplied, 2 –lens, 3 – interferential filter, 4 –

measuring cell, 5 – pfotomultiplier, 6 – amplifier

Obr.54 Chemiluminiscent analysator Horiba1 – light detector, 2 – measuring gas supply, 3 – measuring cell, 4 –

modulation gas valve, 5 – generator of ozone, 6 – clean air supply, 7 –amplifier, 8 – gas output

Obr.56 Magnetic field effect to fifferent matters - paramagneticspenetrate to highest magnetic field. Pole, d- diamagnetics are expeled, f-

paramagnetics stronger penetrate to magnetic field

Obr.57 Magnetical analysator. 1- support for fibre, 2- pole extension, 3-nitrogen filled bulb, 4- mirror, 5- led diode, 6- photo-cell twins

Obr.60 Magnetic analysator. 1-measuring tube, 2-magnetic pole extension, 3,5-heated coils , 4-analysed gas input, 6-circlar chamber, 7-analysed

gas output, 8-second resistor branche of Wheatst. bridge, 10-power supply

ELECTROCHEMICAL ANALYZERS

1) Potentiometry

2) Amperometry: ConductivityPolarographyDepolarisation

Metals in some electrolyte are dissolved into ions. Potential is created. Polarity depends on metal.

atomselectrons

Zn

Negative charge on Zn (ignoble) electrode

electrolyte

Potentials of different electrodes against refence electrodeNernst equation

Obr.65 Princip of pH measurement (potentiometry), 1 – sensingglass electrode, 2 – reference (standard) usually silver chloride electrode or calomelelectrode, 3,4 – inner electrodes, 5 – pH sensitive membrane (Si glass), 6 – solution

of determinate Ph value, 7 –solution of KCl, 8 – diafragma (nonmetalic, iont connection of electrode to analysed electrolyt).

pH is a measure of the acidity or alkalinity of asolution

Fig.66 Amperometry, dependence I=f(U,c)ME – sensing electrode, SE – reference electrode

Obr.64a Electrochemical analyser with solid state electrolyte, thin Pt electrode (potentiometry), p1 – partial pressure (concentration) of oxygen at one electrode, p2 – – partial pressure of oxygen at the other electrode.

ZrO2

Oxyxen penetrates to the negative electrode through a small hole. O2 isionisated because of high temperature room (350 °C) and goes to positive

electrode to leave there their negative charge. Flowing current isproportional to oxygen concentration.

heating hole

ZrO2

Oxygen sensor

Catalytic convertersThe catalytic converter is a device, placed in the exhaust pipe, which converts various emissions into less harmful ones using, generally, a combination of platinum, palladium and rhodium as catalysts. They make for a significant, and easily applied, method for reducing tailpipe emissions.

The lead emissions were highly damaging to human health, and its virtual elimination has been one of the most successful reductions in air pollution.

λ probe catalysator

λ probe Catalytic covertor

cover of catalysator

Principle of engine with catalytic convertorPrinciple of engine with catalytic convertor

Carburatorcontrol

petrolmotor

gaswaste

convertor

λ proberegulator

petrol

Fig. 64d - Fig. 64eAir offer ratio λ – Waste gases behaviour

λ>1 (light mixture):It is necessary to increasepetrol input.

λ<1It is necessary to decreasepetrol input.

V – real air volumeVs – stechiometric required air volume

λ window

Analyser with ionisation by mean of flame1 –thermocouple, 2 – collecting electrode, 3 – flame jet– second electrode, 4 –

ignition electrode, 6 – output of gas, 7 – amplifier, 8 – voltage wiring, 9 – air input, 10 – hydrogene input, 11 – measured gas input

Rarefactive probes1 – oddělovací filtr, 2 – filtr ze skleněné vlny, 3 – skleněná dýza s nadkritickým

průtokem, 4 – ejektor, 6 – přívod kalibračního plynu, 7 – přívod čistého tlakovéhovzduchu, 8 – výstup směsi k analyzátorům

Principle of gas chromatography1 – measured gas input, 2 – carrying gas input – mobile phase, 3 – sampling unit,

4 – chromatographic cell (stationary phase eg. charcoal), 5 – thermostat, 6 –detector, 7 – plotter

Measured gas and carrying gas move at different rates because of relativeattraction to stationary phase. The separation is based on physical principles like

dissolution, adsorption and ions exchange

Succession of the different parts of measured gasmixture through cell

Chromatograph output

Mass Spectrometry1 – source of ionts, 2 – input of measured substance, 3 – electron source (glowing fiber), 4 – positive ionts, 5 – accelerating electrode, 6 –input slot, 7 – magnetic field, 8 –output slot, 9 – heavy ionts10 – light ionts, 11 – measured ionts, 12 –collector, 13 – collector electrode, 14 – current amplifier, 15 – signal processing.

An ionized vapour is passed betweenmagnets which separate the ions by charge to mass ratio. The patternproduced is characteristic of theparticular substance, which can beidentified by comparison withcomputerized „libraries“ of massspectra. For environmental analyses, where several substances occure atonce, mass spectrometry is usuallyused in tandem with anothertechnique – eg. chromatography.

Tab. 27: Meze postřehu pro některé prvky přiatomové absorpční spektrofotometrii

Záznam diferenční pulsní polarografie

Mezepostřehuněkterýchprvků při

neutronovéaktivačníanalýze

Analýza směsi pesticidů plynovým chromatografem

Monitoring oxidantů v ovzduší

Monitoring ozónu