Towards miniaturized sensors for determination of exchangeable potassium in soil samples (original) (raw)
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LookUs Bilisim A.S., 2021
In this study, a novel all-solid-state contact poly(vinylchloride) (PVC) membrane potassium selective sensor with a pyrazole derivative molecule as an ionophore has been developed. The potassium selective sensor has a composition of PVC, ionophore, anion excluder (potassium tetrakis (p-chlorophenyl)borat (KTpClPB)) and plasticizer (bis(2ethylhexyl)adipate (DEHA)) in the ratio of 32.0:4.0:1.0:63.0 (mg). The potassium selective sensor works in a linear concentration range of 1.0×10-5 to 1.0×10-1 M with a low detection limit of 6.02 × 10 −6 M The developed potassium selective sensor works in pH range of 6.0-10.0 and has good repeatability, selectivity and a short response time of 10 seconds. Finally, the developed potassium selective sensor was successfully used in the determination of potassium in tap water and a drug sample. Bu çalışmada, pirazol türevi bir molekülünün iyonofor olarak kullanıldığı yeni tümüyle katı hal kontak poli(vinilklorür) (PVC) membran potasyum sensörü geliştirildi. Potasyum seçici sensör PVC, iyonofor, potasyum tetrakis (p-klorofenil)borat (KTpClPB)) ve plastikleştirici (bis (2-etilheksil)adipat (DEHA))'ın 32.0:4.0:1.0:63.0 (mg)'lık bileşimine sahiptir. Geliştirilen potasyum seçici sensör, 6.02×10-6 M'lık düşük algılama limiti ile 1.0×10-5-1.0×10-1 M konsantrasyon aralığında doğrusal olarak çalışmaktadır. Geliştirilen potasyum seçici sensör pH 6.0-10.0 aralığında çalışmaktadır, iyi tekrarlanabilirlik, iyi seçicilik ve 10 saniyelik kısa cevap zamanına sahiptir. Son olarak, geliştirilen potasyum seçici sensör musluk suyu ve ilaç örneğinde potasyum tayininde başarıyla kullanılmıştır.
A double-membrane ion-selective electrode for the potentiometric determination of potassium
Microchemical Journal, 1989
A potassium double-membrane ion-selective electrode based on an internal conductor membrane made of tetrabutylammonium bromide and another external electroactive membrane formed with the precipitate 18-crown6/phosphotungstic acid was prepared, with dibutylphthalate as the plasticizer and poly(viny1 chloride) as the inert matrix. The electrode exhibited a linear response in the concentration range l-lO-4.5 M potassium, with a Nemstian slope (55.50 mV decade-') at 25 + 0.2"C. The reproducibility (coeffkient of variation) was 0.9% (n = 10 determinations).
Transactions of the ASABE, 2007
Knowledge of the spatial variation of soil attributes is critical for precision agriculture. On-the-go soil sensors have been able to provide relatively high mapping density while assessing this variation. A new ion-selective electrode (ISE) based approach was developed and tested for simultaneous mapping of soil pH, residual nitrate (NO 3-), and soluble potassium (K +) contents. In this article, results of laboratory experiments investigating the effects of key measurement factors on ISE performance are presented. In addition to four different soils, these factors included: soil/water ratio (SWR), quality of water used for electrode rinsing (QWR) and for ion extraction (QWE), presence of ionic strength adjuster (ISA), and solution agitation (stirring). After the targeted ion activity presented by different soils, SWR was the second most influential factor causing increased measurement variance, while the influence of QWE was only significant for pH measurements. Based on this study, the following measurement parameters were recommended: agitated purified water extraction without ISA, addition of a fixed amount of water (preferably 1:1 soil/water ratio), and use of regular (tap) water for electrode rinsing.
Development and calibration of an electrolytic cell for ion determination in a soil solution
Acta Scientiarum. Technology, 2015
An electrolytic cell was developed to monitor soil modifications after crop fertigation with wastewaters from agroindustrial plants. The device was first calibrated with different levels of potassium chloride dissolved in aqueous solutions at various temperatures. Nernst´s model was used to fit the voltage indicated from the electrolytic cell versus the ionic activity of the potassium from the aqueous solutions of electrical conductivity and known ionic concentrations and the diluted wastewater samples. The equipment accurately indicated the tensions after appropriated correction of the electrical current and the temperature. The device estimated with accuracy the ionic coefficient of activity, the concentration of the potassium chloride and the concentration of the ion K dissolved in the agro-industrial wastewater.
Simultaneous Analysis of Soil Macronutrients Using Ion-Selective Electrodes
Soil Science Society of America Journal, 2007
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. M onitoring nutrient levels in soils is necessary to effi ciently use fertilizers and minimize the environmental impact of fertilization practices. Conventional soil testing methods, however, which combine soil sampling in the fi eld and chemical analysis in the laboratory, are costly and time consuming, thereby limiting the number of samples analyzed in the fi eld and making it diffi cult to characterize spatial variability in soil nutrient concentrations in an agricultural fi eld (Schepers and Schlemmer, 1998; Artigas et al., 2001). A higher resolution than the current commercially practiced 1-ha grid sampling is needed for site-specifi c crop management to more accurately characterize within-fi eld variability (Schepers and Schlemmer, 1998). For example, accurate monitoring of soil NO 3 levels has been limited by relatively high temporal and spatial variability of NO 3-N in the fi eld (Magdoff et al., 1984; Ruffo et al., 2005), leading to the need for real-time measurements with a high sampling intensity (Birrell and Hummel, 2001). The need for fast in-fi eld monitoring has led to the investigation of ion-selective electrode (ISE) technology for determining soil chemical properties. Among the advantages of ISE technology over current analytical methods (e.g., spectroscopic techniques) are simplicity of use, direct measurement of analyte, sensitivity across a wide concentration range, low cost, and portability (Carey and Riggan, 1994). An important component of an ISE is the ion-selective membrane that responds to one analyte in the presence of other ions in a solution. Due to an increased demand for measurement of new ions, and advances in micro-electro-mechanical systems technology, signifi cant progress has been made in recent years in the development of various ion-selective membranes in the area of analytical chemistry. There are currently ion-selective membranes available for most of the important soil nutrients, including NO 3 ,
Evaluation of Ion-Selective Membranes for Real- Time Soil Nutrient Sensing
A key to developing a real time, automated soil nutrient sensor depends on the ability to effectively extract soil nutrients from a soil sample and precisely detect them in a very short time period. An ion-selective field effect transistor (ISFET) chip has proven to be a good candidate for use in real-time soil nutrient sensing because of its rapid response and low sample volume. This paper describes the evaluation of nitrate ionselective membranes and the investigation of the interaction between the ion-selective membranes and soil extracting solutions. The response characteristics of the membranes and their suitability for use for real-time soil nutrient sensing were investigated through evaluation of their sensitivity and selectivity using 16 ion selective electrodes (ISEs) in a computer-controlled system. All membranes showed an approximately linear Nernstian response when nitrate concentrations were above 10 -3 M, irrespective of extracting solution type. At low nitrate concentrations, below 10 -4 M, both the extracting solution and ligand types significantly affected the sensitivity and selectivity of each membrane. A TDDA-NPOE membrane showed greater sensitivity to nitrate than did the MTDA-NPOE and MTDA-TOTM membranes. In addition, the selectivity of the TDDA membrane was superior to that of the MTDA membranes when bicarbonate, chloride, and bromide were considered as the interfering ions.
Ion-Selective Electrodes as Simple and Inexpensive Detectors for Soil Analysis
The problem of heavy metal contamination arising from abandoned mining operations such as at Silvermines, Ireland, represents a challenge in terms of monitoring the extent of contamination in the surrounding area. Ion-selective electrodes (ISEs) are very sensitive and inexpensive analytical tools that can be applied to the determination of heavy metals that were until recently thought to be inappropriate for many environmental applications due to relatively high limits of detection. In this work, we examine the possibility of using ISEs for monitoring heavy metals in the environment using approaches that offer improved limits of detection. A more environmentally friendly method for extracting heavy metals from soil samples based on dilute nitric acid is also evaluated. The ISEs used were Pb 2+-selective solid-contact electrodes with polypyrrole as the inner contact. As the existence of an inner water layer between the ion-selective membrane and the solid support can significantly affect the electrode response and detection limit, electrodes were first tested for the presence of a water layer. Water layer was observed in electrodes having ion selective membrane deposited directly to the solid support (i.e. no conductive polymer as inner layer). The presence of polypyrrole as an inner layer resulted in negative water layer test. Only electrodes that tested negative for this water layer were used for measurement of Pb concentrations. In calibration experiments, the electrodes showed a detection limit of 1.2x10-6 M (0.25ppm). The ISEs were used to measure the concentration of lead in digested field samples, and the results were compared with a reference method (AAS). The average percent of recovery for the ISEs when compared to AAS was 65% which is to a large extent due to differences in the fundamental response characteristics of the two methods, as ISEs only detect the free metal, whereas AAS detects total concentration. A good correlation between the two methods was observed which suggests that ISEs could be used for in-situ direct measurements.
Development and calibration of an electrolytic cell for ion determination in a soil solution
An electrolytic cell was developed to monitor soil modifications after crop fertigation with wastewaters from agroindustrial plants. The device was first calibrated with different levels of potassium chloride dissolved in aqueous solutions at various temperatures. Nernst´s model was used to fit the voltage indicated from the electrolytic cell versus the ionic activity of the potassium from the aqueous solutions of electrical conductivity and known ionic concentrations and the diluted wastewater samples. The equipment accurately indicated the tensions after appropriated correction of the electrical current and the temperature. The device estimated with accuracy the ionic coefficient of activity, the concentration of the potassium chloride and the concentration of the ion K dissolved in the agro-industrial wastewater. Desenvolvimento e calibração de um equipamento para determinação da concentração de íons na solução do solo RESUMO. Uma célula eletrolítica foi desenvolvida para monitorar as modificações do solo após a fertirrigação de culturas com águas residuárias agroindustriais. Neste primeiro passo, o dispositivo fabricado foi calibrado utilizando diferentes níveis de cloreto de potássio dissolvido em soluções aquosas sob várias temperaturas. O modelo de Nernst foi utilizado para ajustar a tensão indicada a partir da célula electrolítica versus a actividade iónica do potássio a partir de soluções aquosas de condutividade elétrica e concentração iônica conhecidas e amostras de águas residuárias diluídas. O equipamento indicou com precisão as tensões após a correção apropriada tanto da corrente eléctrica como da temperatura. O dispositivo estimou com precisão o coeficiente de atividade iónica, a concentração do cloreto de potássio e a concentração do íon K dissolvido nas águas residuárias agroindustriais. Palavras-chave: atividade iônica, potássio, água residuária, fertirrigação.