Beschreibung:
<jats:p>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<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="E1"><mml:mn>25</mml:mn><mml:mtext> cm</mml:mtext><mml:mo>×</mml:mo><mml:mn>22</mml:mn><mml:mtext> cm</mml:mtext><mml:mo>×</mml:mo><mml:mn>10</mml:mn><mml:mtext> cm</mml:mtext></mml:math>, weighs circa 3 kg, and costs 650 €. System performance was evaluated for different chemistries without changing hardware configuration for determinations of (i)<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="E2"><mml:msup><mml:mtext>Fe</mml:mtext><mml:mrow><mml:mn>3</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math>with<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="E3"><mml:msup><mml:mtext>SCN</mml:mtext><mml:mtext>-</mml:mtext></mml:msup></mml:math>, (ii) iodometric nitrite determination, (iii) phenol with sodium nitroprusside, and (iv) 1-naphthol-N-methylcarbamate (carbaryl) with<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="E4"><mml:mi>p</mml:mi></mml:math>-aminophenol. The detection limits were estimated as 22, 60, 25, and 60 ng<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="E5"><mml:msup><mml:mtext>mL</mml:mtext><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:math>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</jats:p>