Flow Injection Analysis (Chapter 33) Automatic no feedback to control Automated-feedback to control Advantages of Automation (1)Economic operator costs reduced waste human errors (2)Speed (3)Precision Disadvantages of Automation: (1)Cost Initial purchase Setup cost (2)Inflexible Two types of auto analysis (A)Discrete/batch-sample remains isolated throughout (robot,no cross-contamination problem) (B)Continuous-sample introduced into stream(simpler instrumentation,more efficient) CEM 333 page 13.1
Flow Injection Analysis (Chapter 33) Automatic - no feedback to control Automated - feedback to control Advantages of Automation: (1) Economic operator costs reduced waste human errors (2) Speed (3) Precision Disadvantages of Automation: (1) Cost Initial purchase Setup cost (2) Inflexible Two types of auto analysis (A) Discrete/batch - sample remains isolated throughout (robot, no cross-contamination problem) (B) Continuous - sample introduced into stream (simpler instrumentation, more efficient) CEM 333 page 13.1
Flow Injection Analysis (FIA)developed in response to need for automated analysis -especially in clinical field Fig 33-1 Peristaltic pump Reactor Sample Photometer nL/mir coil 50cm W ⊙+To Fe3+ 0.50mm waste (a) A 08 (b) K75 (c) 6 6 min 30 15s 0 0.0 Time (b) CEM 333 page 13.2
Flow Injection Analysis (FIA) developed in response to need for automated analysis - especially in clinical field Fig 33-1 CEM 333 page 13.2
In first instruments,regular air bubbles introduced to (i)reduce dispersion(diffusion along tube) (ii)improve mixing Air-segmented continuous flow analysis (ASCFA) Mixing Air Bubbles Detector A Reagent AO Reagent B Reaction Net Flow Bolus Flow Profile But.bubbles (i)increase analysis time (ii)require bubble introduction/removal (bubble gate) (iii)increase startup/settle time CEM 333 page 13.3
In first instruments, regular air bubbles introduced to (i) reduce dispersion (diffusion along tube) (ii) improve mixing Air-segmented continuous flow analysis (ASCFA) Reagent A Reagent B Air Mixing Bubbles Net Flow Bolus Flow Profile Reaction Detector But, bubbles (i) increase analysis time (ii) require bubble introduction/removal (bubble gate) (iii) increase startup/settle time CEM 333 page 13.3
However,in FIA system with narrow id tubing and low flow rates no need for bubbles At injection,sample zone (plug)concentration profile is rectangular Profile changes downstream (i)Laminar flow profile develops due to friction with walls Net Flow Laminar Flow Profile (ii)Radial diffusion from center to walls of tube (iii)Longitudinal diffusion in forward and backward flow directions CEM 333 page 13.4
However, in FIA system with narrow id tubing and low flow rates no need for bubbles At injection, sample zone (plug) concentration profile is rectangular Profile changes downstream (i) Laminar flow profile develops due to friction with walls Net Flow Laminar Flow Profile (ii) Radial diffusion from center to walls of tube (iii) Longitudinal diffusion in forward and backward flow directions CEM 333 page 13.4
Direction of flow Time Time Time Time (a ) (c) (d) Fig 33-5 When flow rate/tube id is small (d)is approached-no need for bubbles！ Radial diffusion from walls to center helps minimize cross- contamination between sample plugs CEM333 page 13.5
Fig 33-5 When flow rate/tube id is small (d) is approached - no need for bubbles! Radial diffusion from walls to center helps minimize crosscontamination between sample plugs CEM 333 page 13.5