Disposable Receptor-Based Optical Sensor for Nitrate

Abstract

A new optical absorption-based disposable sensor for nitrate is described. The nitrate-sensitive element is a bicyclic cyclophane receptor next to a suitable pH-sensitive lipophilic dye immobilized in a plasticized polymeric membrane. The rigid amide-based receptor with C3 symmetry controls the anion selectivity pattern of the optical element. The optical selectivity coefficients obtained for nitrate over a variety of naturally occurring anions in natural waters meet the requirements for the determination of nitrate in waters. The disposable sensor responds to nitrate rapidly-the typical response time is 5 min-and reversibly over a wide dynamic range (26 microM-63 mM) with sensor-to-sensor reproducibility (relative standard deviation, RSD, 3.68%, as log aNO3-, at the medium level of the range and RSD 1.39% for repeated measurements with the same sensor). The performance of the optical disposable sensor was tested for the analysis of nitrate in different types of natural waters (river, well, spring), validating results against a reference procedure. The proposed method is quick, inexpensive, selective, and sensitive and uses only conventional instrumentation.

Potassium disposable optical sensor based on transflectance and cromaticity measurements

“…Different properties have been used in optical disposable sensors for measurement, including radiation absorption by transmission [1,2] as well as other techniques which rely on luminescence, both fluorescence [3] and phosphorescence [4] and chemiluminescence [5,6]. The measurement of fluorescence excited within the evanescent field has been proposed in connection with a one-shot sensor chip [7].…”

“…We have studied the use of transparent membranes containing the necessary reagent in disposable sensors for the optical determination of different analytes measuring the optical property (absorption, luminescence) in transmission mode [2,[17][18][19]. In this paper we investigate the use of these disposable sensors in reflectance mode.…”

Portable light-emitting diode-based photometer with one-shot optochemical sensors for measurement in the field

“…23,25 This analytical parameter is experimentally obtained from the change in the optical properties of the membrane. In the case of absorbance measurements, it is obtained from…”

“…Everything, from the one-shot sensor to the signal processing electronics, has also been designed with the aim of applying a novel measurement procedure to dissolve analytes in natural waters and beverages simply and with enough sensitivity and repeatability for in situ measurement at low cost. As examples of one-shot sensors to be used along with the measurement procedure described here, we have selected two ionophore-based membranes for potassium 23,24 and nitrate 25 previously reported by us for the analysis of these species in water.…”

Análisis químico del extracto peciolar para evaluar el estado nutricional en la vid

“…Además, es una técnica más económica y rápida en relación a un análisis convencional (MacKown & Weik, 2004;Capitán-Vallvey et al, 2005). Este análisis se ha utilizado para determinar el estado nutricional en olivo (Hidalgo et al, 2006) y en distintos cultivos hortícolas, tales como ajo (Gaviola & Lipinski, 2004), tomate (Taber, 2001;Cadahía López, 2005), melón (Fontes et al, 2003), alcachofa (Rodrigo et al, 2005(Rodrigo et al, , 2006, brócoli (Villeneuve et al, 2002) y zapallo (Studstill et al, 2003).…”