Evaluation of a Multicommuted Flow System for PhotometricEnvironmental Measurements

Abstract

A portable flow analysis instrument is described for in situ photometric measurements. This system is based on light-emitting diodes (LEDs) and a photodiode detector, coupled to a multipumping flow system. The whole equipment presents dimensions of 25 cm × 22 cm × 10 cm, weighs circa 3 kg, and costs 650 €. System performance was evaluated for different chemistries without changing hardware configuration for determinations of (i) Fe3+ with SCN-, (ii) iodometric nitrite determination, (iii) phenol with sodium nitroprusside, and (iv) 1-naphthol-N-methylcarbamate (carbaryl) with p-aminophenol. The detection limits were estimated as 22, 60, 25, and 60 ng mL -1 for iron, nitrite, phenol, and carbaryl at the 99.7% confidence level with RSD of 2.3, 1.0, 1.8, and 0.8%, respectively. Reagent and waste volumes were lower than those obtained by flow systems with continuous reagent addition. Sampling rates of 100, 110, 65, and 72 determinations per hour were achieved for iron, nitrite, phenol, and carbaryl determinations

Development of a high sensitive automatic setup for screening of microcystins in surface waters by employing a LED-based photometric detector

“…The reduced volume of waste generated (100 L per determination) allows us to conclude that the proposed setup satisfies the Analytical Green Chemistry requirement concerning environmental sustainability [35][36][37].…”

A LED based photometer for solid phase photometry: zinc determination in pharmaceutical preparation employing a multicommuted flow analysis approach

“…This distance can be varied by changing the amount of solid material inserted into the flow cell channel. The control line (d 0 ) was coupled to the digital interface output port 11 in order to allow the LED shining to be controlled by a software.…”

“…[6][7][8][9] Its narrow emission band (l = 25 nm) has enabled it to be used without a monochromator system, thus simplifying the photometer design. [10][11][12] Multicommuted flow analysis process affords facilities to design active flow setup constituted by solenoid valves, which have been assembled to work as an independent commutator unit, thus allowing facilities to handle sample and reagent solutions controlled by microcomputer. [8][9][10][11]13,14 Zinc is present in all living cells as a constituent of several molecules involved in proteins, lipids and carbohydrates metabolism, as well as several enzymes.…”

“…[10][11][12] Multicommuted flow analysis process affords facilities to design active flow setup constituted by solenoid valves, which have been assembled to work as an independent commutator unit, thus allowing facilities to handle sample and reagent solutions controlled by microcomputer. [8][9][10][11]13,14 Zinc is present in all living cells as a constituent of several molecules involved in proteins, lipids and carbohydrates metabolism, as well as several enzymes. 15,16 In this sense, zinc is considered as an essential element for all animals, including humans.…”

Desenvolvimento de instrumentação e procedimentos automáticos para determinação de arsênio e fluoreto em águas empregando multicomutação em fluxo e detecção fotométrica

“…A procedimento proposto apresentou resposta linear na faixa de 2,5 a 40 µg L -1 (r = -0,995), limite de detecção de 0,3 µg L -1 , desvio relativo menor que 6,5 %, freqüência de amostragem de 25 h Reis et al, (1994). conforme descrito por Ródenas-Torralba, et al, (2006 Bergamin et al, (1978).…”