AIR SAMPLING DEVICES.pptx

AIR SAMPLING DEVICES.pptx

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  AIR SAMPLING DEVICES ASSISTANT PROFESSOR DEPARTMENTOF MICROBIOLOGY
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  INTRODUCTION • Air canharvest many different kinds of microorganisms. • Monitoring air quality is an essential criterion in quality control in laboratories. • Air quality monitoring can be done either by collecting air samples or passively by settled plate methods. • The microbial air sampler is a way to collect air samples for active air quality monitoring.
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  TYPES AIR SAMPLING DEVICES BASEDON MEDIUM LIQUID MEDIUM SOILD MEDIUM BASED ON SIZE SETTLING UNDER GRAVITY AIR CENTRIFUGE FILTRATION IMPINGEMENT OF LIQUIDS IMPINGEMENT ON SOILDS
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  SETTLING UNDER GRAVITY •Method used for collecting the air with particles by gravity. • Eg: Hesse’s Tube 1 • Hesse’s tube  horizontal glass tube + layer of solid medium at the bottom 2 • Air pass through the tube & particles with microbes 3 • Analysis of Microbes
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  AIR CENTRIFUGE • Developedby Wells – 1993. • The air containing particles are centrifuged on to the culture medium. SAMPLE AIR PASSED THROUGH TUBE & ROTATED ON ITS LONG AXIS BACTERIA PRESENT IN THE PARTICLES SETTLE ON THE MEDIUM ANALYSIS
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  FILTRATION • Simple methodfor collecting air. • The filter can be made up of glass fibre, sand, alginate wool etc., • The recovery of organisms from the filter is not easy Tube sampler
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  FILTRATION TUBE SAMPLER: 1 • Tubewith inlet at the top and outlet at the bottom • Sand layer used as filter 2 • Sterilize the tubes • Air is passed through it 3 • Particles deposited on the medium • Analysis
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  • RAISED IMPINGER• BEAD – BUBBLER DEVICES IMPINGEMENT INTO LIQUIDS
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  IMPINGEMENT INTO SOLIDS SOLIDS HOLLAENDER& DALLA VALLE SAMPLER SLIT SAMPLER SIEVE SAMPLER
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  A. HOLLAENDER &DALLA VALLE SAMPLER • Brass container with removable bottom. • Lower portion contain agar medium. • Air passes through the funnel. • The air borne microorganisms are impinged on the agar medium. • Simple, portable and efficient method.
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  B. SLIT SAMPLER •Has an enclosed chamber. • Air drawn into the sampler through the slit and the particles get impinged on the medium. • The plates are incubated at 37C for 24 hours.
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  C. SIEVE SAMPLER MULTISTAGESEIVE SAMPLER SINGLESTAGE SEIVE SAMPLER • Simple & efficient method. • The particles are separated based on size.
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  D. ELECTROSTATIC PRECIPITATION •Litton Air Sampler. • The air is allowed to pass through the electrodes. • The charged particles fall on the rotating disc which is later fed into the collecting fluid.
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  QUICK RECALL • Whatis meant by air sampling? • Techniques involved based on medium? • Types of methods employed based on size? • Example of settling under gravity. • Two example of impingement into liquids. • Principle of Sieve sampler. • Electrostatic precipitation is based on what? 14
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