{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,17]],"date-time":"2025-12-17T08:54:27Z","timestamp":1765961667837,"version":"build-2065373602"},"reference-count":53,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2023,2,13]],"date-time":"2023-02-13T00:00:00Z","timestamp":1676246400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"GEOMAR, Helmholtz for Ocean Research Centre, Kiel, Germany"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Autonomous on-site monitoring of orthophosphate (PO43\u2212), an important nutrient for primary production in natural waters, is urgently needed. Here, we report on the development and validation of an on-site autonomous electrochemical analyzer for PO43\u2212 in seawater. The approach is based on the use of flow injection analysis in conjunction with a dual electrochemical cell (i.e., a bi-potentiostat detector (FIA-DECD) that uses two working electrodes sharing the same reference and counter electrode. The two working electrodes are used (molybdate\/carbon paste electrode (CPE) and CPE) to correct for matrix effects. Optimization of squarewave voltammetry parameters (including step potential, amplitude, and frequency) was undertaken to enhance analytical sensitivity. Possible interferences from non-ionic surfactants and humic acid were investigated. The limit of quantification in artificial seawater (30 g\/L NaCl, pH 0.8) was 0.014 \u00b5M for a linear concentration range of 0.02\u20133 \u00b5M. The system used a Python script for operation and data processing. The analyzer was tested for ship-board PO43\u2212 determination during a four-day research cruise in the North Sea. The analyzer successfully measured 34 samples and achieved a good correlation (Pearson\u2019 R = 0.91) with discretely collected water samples analyzed using a laboratory-based colorimetric reference analyzer.<\/jats:p>","DOI":"10.3390\/s23042123","type":"journal-article","created":{"date-parts":[[2023,2,14]],"date-time":"2023-02-14T01:41:06Z","timestamp":1676338866000},"page":"2123","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["The Use of Bi-Potentiostat as a Simple and Accurate Electrochemical Approach for the Determination of Orthophosphate in Seawater"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8447-2907","authenticated-orcid":false,"given":"Mahmoud Fatehy","family":"Altahan","sequence":"first","affiliation":[{"name":"Chemical Oceanography Department, GEOMAR Helmholtz Centre for Ocean Research, 24148 Kiel, Germany"},{"name":"Central Laboratory for Environmental Quality Monitoring, National Water Research Centre, El-Qanater El-Khairia 13621, Egypt"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2575-7814","authenticated-orcid":false,"given":"Mario","family":"Esposito","sequence":"additional","affiliation":[{"name":"Chemical Oceanography Department, GEOMAR Helmholtz Centre for Ocean Research, 24148 Kiel, Germany"}]},{"given":"Boie","family":"Bogner","sequence":"additional","affiliation":[{"name":"Chemical Oceanography Department, GEOMAR Helmholtz Centre for Ocean Research, 24148 Kiel, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3061-2767","authenticated-orcid":false,"given":"Eric P.","family":"Achterberg","sequence":"additional","affiliation":[{"name":"Chemical Oceanography Department, GEOMAR Helmholtz Centre for Ocean Research, 24148 Kiel, Germany"}]}],"member":"1968","published-online":{"date-parts":[[2023,2,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"493","DOI":"10.1126\/science.271.5248.493","article-title":"Redox stabilization of the atmosphere and oceans by phosphorus-limited marine productivity","volume":"271","author":"Ingall","year":"1996","journal-title":"Science"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1071\/MF13059","article-title":"Nutrients and eutrophication: Introduction","volume":"64","author":"McDowell","year":"2013","journal-title":"Mar. 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