Phosphate In Water Samples Research Articles

An automated analyzer for the simultaneous determination of silicate and phosphate in seawater

Accurate and automated determination methods for silicate and phosphate are in high demand to improve understanding of biogeochemistry and ecology in dynamic and complex estuarine-coastal ecosystems. Here, a portable automated analyzer is reported for the simultaneous determination of silicate and phosphate in water samples with varying salinity. After comprehensive optimization of the chemical reactions and flow manifold, the system demonstrated limits of detection of 0.09 and 0.05 μmol L−1 for silicate and phosphate, respectively, exhibiting linearity at concentrations up to 400 and 200 μmol L−1 with automated dilution, achieving relative standard deviations (n = 11) of 0.27% (20 μmol L−1 silicate), 0.51% (5 μmol L−1 phosphate) and 0.80% (1 μmol L−1 phosphate). Compared with similar automated flow analyzers, the system exhibited advantages, such as low consumption of reagents (10–20 μL/sample), portability (4.8 kg), rapid start-up (5 min), reliability (automated analysis of quality control sample) and applicability within a broad salinity range (from 0 to 35) allowing analysis of dynamic estuarine and seawater samples. The system was successfully applied to a routine monitoring program by a national marine station and is potentially suitable for installation on different observation platforms for on-line and real-time underway analysis of nutrients in coastal areas.

Colorimetric Phosphate Detection Using Organic DFB Laser Based Absorption Spectroscopy.

A novel compact laser absorption spectrometer is developed for colorimetric detection. We demonstrate the realization of the system as well as example measurements of phosphate in water samples based on the malachite green (MG) method. A phosphate concentration range of to (which corresponds to a molar concentration range of to ) is investigated. This photometer demonstrates the ease of integration of organic distributed feedback (DFB) lasers and their miniaturizability, leading the way toward optofluidic on-chip absorption spectrometers. We constructed an optically pumped organic second-order DFB laser on a transparent substrate, including a transparent encapsulation layer, to have access to both emission directions of the surface-emitting laser. Using the two different surface emission directions of the laser resonator allows monitoring of the emitted light intensity without using additional optical elements. Based on these advances, it is possible to miniaturize the measurement setup of a laser absorption spectrometer and to measure analytes, such as phosphate.

Alcohol-Triggered Capillarity through Porous Pyrolyzed Paper-Based Electrodes Enables Ultrasensitive Electrochemical Detection of Phosphate.

The sensing field has shed light on an urgent necessity for field-deployable, user-friendly, sensitive, and scalable platforms that are able to translate solutions into the real world. Here, we attempt to meet these requests by addressing a simple, low-cost, and fast electrochemical approach to provide sensitive assays that consist of dropping a small volume (0.5 μL) of off-the-shelf alcohols on pyrolyzed paper-based electrodes before adding the sample (150 μL). This method was applied in the detection of phosphate after the formation of the phosphomolybdate complex (250-860 nm in size). Prior drops of isopropanol allow for the fast penetration of the sample through pores of this hydrophobic paper, delivering hindrance-free redox reactions across increasing active areas and ultimately improving the detection performance. The sensitivity (-1.9 10-6 mA cm-2 ppb-1) and limit of detection (1.1 ppb) were improved, respectively, by factors of 33 and 99 over the data achieved without the addition of isopropanol, listing among the lowest values when compared with those results reported in the literature for phosphate (expressed in terms of the concentration of phosphorus). The approach enabled the quantification of this analyte in real samples with accuracies ranging from 87 to 103%. Furthermore, preliminary measurements demonstrated the successful performance of the electrodes with prior addition of other widely used alcohols, that is, methanol and ethanol. These results may extend the applicability of the method. In special, the scalability and eco-friendly character of the electrode fabrication combined with the sensitivity and simplicity of the analyses make the developed platform a promising alternative that may help to pave the way for a new generation of disposable sensors toward the daily monitoring of phosphate in water samples, thus contributing to prevent ecological side effects.

Pyruvate Oxidase Biosensors Based on Glassy Carbon Electrodes Modified with Carbon Nanotubes and Poly(Neutral Red) Synthesized in Ethaline Deep Eutectic Solvent

AbstractA novel nanostructured platform for pyruvate oxidase biosensors comprises poly(neutral red) (PNR) prepared by electropolymerization of NR in ethaline deep eutectic solvent (DES) with acid dopant, on a multiwalled carbon nanotubes (MWCNT) modified glassy carbon electrode (GCE). Characterization was by cyclic voltammetry and electrochemical impedance spectroscopy and morphology was examined by scanning electron microscopy. Ascorbate and H2O2 gave a better response at PNRDES/GCE than at PNRaq/GCE. Biosensors for pyruvate and phosphate, immobilizing pyruvate oxidase onto PNRDES/MWCNT/GCE enabled selective determination of pyruvate and phosphate, with micromolar limits of detection. Pyruvate was determined in onion samples and phosphate in water samples.

Fast room temperature cloud point extraction procedure for spectrophotometric determination of phosphate in water samples

A novel fast room temperature cloud point extraction (RT-CPE) procedure for preconcentration and spectrophotometric determination of phosphate based on the heteropoly blue formation was developed. The proposed method includes the formation of yellow molybdoantymonatophosphoric heteropoly complex, its extraction into Triton X-100 micellar phase obtained at room temperature and reduction of heteropoly complex by ascorbic acid solution in ethanol and absorbance measurement of heteropoly blue at 790 nm. Under optimal conditions (1% (v/v) of Triton X-100 and 0.05 M of ammonium benzoate for initiating of RT-CPE; 0.13 M ethanolic solution of ascorbic acid for reduction of heteropoly complex and dilution of surfactant rich phase), the calibration graph is linear in the range of phosphate concentrations of 1.58–63 μg L−1. The proposed RT-CPE procedure has been successfully applied to preconcentration phosphates and its spectrophotometric determination in water samples.

A simple, highly selective and ultra-sensitive “off-on-off” fluorescent chemosensor for successive detection of aluminum ion and phosphate in water samples

A simple, highly selective and ultra-sensitive “off-on-off” fluorescent chemosensor L for successive detection of Al3+ and PO43− was synthesized and characterized. Sensor L showed a remarkable and highly selective fluorescence enhancement towards Al3+ against other interfering cations, owing to the suppression of intramolecular charge transfer (ICT) mechanism and CHN isomerization. A good linear relationship (R2 = 0.9974) was obtained between the fluorescence emission intensity of L and the concentration of Al3+ (0.025–2.0 μM) with the detection limit of 3.8 nM, which is much lower than the most literature reported. And the binding stoichiometry between L and Al3+ is 1:1 according to Job's Plot and ESI-MS. The resultant complex can be further utilized as a secondary probe for determination of PO43− with the detection limit as low as 0.56 μM. Meanwhile, the sensor L was successfully applied to detect Al3+ in real water, illustrating that sensor L was a promising alternative route for Al3+ detection. Additionally, the sensing mechanism of L to Al3+ was further demonstrated in detail by IR and 1H NMR titration experiment. The successive recognition feature of sensor L has the potential to quantitative analysis of Al3+ and PO43− in environment samples.

A novel platform based on gold nanoparticles chemically impregnated polyurethane foam sorbent coupled ion chromatography for selective separation and trace determination of phosphate ions in water

The sorption characteristics of phosphate ions from aqueous molybdate solution of pH ≤ 2 onto malachite green (MG) impregnated thiophenol (TP) functionalized Au nanoparticles based polyurethane foam (PUF) solid platform (MG-AuNPs-treated PUF) was studied. Phosphate uptakes followed Langmuir and Freundlich models. Based on the retention profile, a dual mechanism involving a “weak base anion exchanger i.e. solvent extraction” and a “surface adsorption” of phosphate retention as complex ion associate {[MG]+.[H2PMo12O40]−}PUF is anticipated. Complete retention of phosphate at various concentrations (0.01–100.0 μg mL−1) onto the sorbent packed column at 3–5 mL min−1 flow rate was achieved. A highly sensitive strategy for enriching, quantitative recovery and trace determination of phosphate in water using the sorbent packed column was developed. Under the optimized parameters, a linear concentration range of 0.07–25 μg L−1 and limits of detection (LOD) and quantification (LOQ) of 0.02 and 0.07 μg L−1 phosphate were achieved, respectively. The proposed and reference methods for analysis of phosphate in water samples were subjected to statistical treatment (student's t and F tests) at 95% confidence with no significant difference indicating the precision and accuracy of the proposed assay. The settled sorbent in flow mode was robust sufficient to be reused for five times without significant decrease in its performance. The intraday repeatability and interday stability of the established sorbent packed column towards phosphate (10.0 μg L−1) determination was studied. An estimated coefficient of variation less than ±5% was achieved revealing the suitably of the modified PUFs in column mode. The established column enabled multiple enrichment of phosphate from water and expanded the range of phosphate level which can be determined in water.

Evaluation of Water Quality Index of Water Bodies Channarayapatna Taluk, Karnataka Region, India

Present communication deals with a study of Physico-chemical parameters such as pH, Temperature, Total Suspended Solids, Turbidity, Dissolved Oxygen, Biochemical Oxygen Demand, Nitrate and Phosphate in water samples of Channarayapatna, Janivara, Anekere and Baghur water bodies in Channarayapatna taluka, Karnataka state of India. The water quality of the samples was compared with standard values given by World Health Organization (WHO) and United State Salinity Laboratory for drinking and irrigation purposes. Water Quality Index (WQI) was also calculated to know the overall quality of water samples. Water quality index (WQI) of Surface water body of various Sampling locations of Channarayapatna taluka, Karnataka ranged between 61.82 and 68.27 indicates the fair quality of water. The water quality index is calculated by indicator (100-point scale) shows that water is suitable for drinking purposes only after pretreatment like filtering, boiling, reverse osmosis and electro dialysis. WQI can play a big role in justifying the water pollution problems after encountered in different surface water bodies. Application of Water Quality Index (WQI) in this study has been found useful in assessing the overall quality of water and to get rid of judgment on quality of the surface water.Int J Appl Sci Biotechnol, Vol 4(4): 475-482

The alternative use of layered double hydroxides as extraction medium coupled with microcomplexation for determination of phosphate in water samples

A simple, rapid, in situ, and green extraction combined with a microcomplexation has been developed for the spectrophotometric determination of phosphate in water samples. Through their formation, layered double hydroxides (LDHs) were employed as the extraction medium, instantly commenced by a rapid addition of a mixed solution of Mg2+ and Al3+ ions into alkaline phosphate solution. After the extraction, LDH precipitate containing phosphate was dissolved by sulfuric acid and the released phosphate was subsequently detected via its complexation with molybdate in the presence of antimonyl and ascorbic acid. Under optimum conditions, the linearity in the range of 5–200μgL−1, with the correlation coefficient (r2) of 0.9969, and the enrichment factor (EF) of 14 were obtained. The limit of detection (LOD) of 5μgL−1 and good precision, with the relative standard deviations (RSDs) less than 8.16%, were achieved. The proposed method was successfully applied to determine phosphate in water samples and the relative recoveries of 72.97–115.32% were obtained.

Energy‐Dispersive X‐Ray Fluorescence Spectrometric Determination of Phosphate in Water Samples via a 12‐Molybdophosphate–Crystal Violet Complex

A simple and eco‐friendly procedure for determining total phosphate content in water has been developed by combining a miniaturized ion‐associated complex‐based preconcentration method with energy‐dispersive X‐ray fluorescence spectrometry (EDXRF). The method is based on indirect determination of phosphorus using molybdenum present in the ion‐associated complex formed by 12‐molybdophosphate and crystal violet. Since phosphorus is determined indirectly, via fluorescent radiation of molybdenum, the difficulties stemming from low fluorescence yield and low energy of phosphorus radiation can be successfully overcome. A good mole ratio of phosphorus to molybdenum (1:12) and a sensitive Kα line of molybdenum make it possible to determine low phosphorus concentrations. Under optimized conditions, a good linearity (up to 2 μg mL−1 of phosphorus, r = 0.9991), and a detection limit of 1.3 ng mL−1 were achieved. The total relative standard deviation (RSD) for EDXRF determination of phosphorus, following precipitation of the ion‐associated complex and its dissolution in a microdrop of 1‐hexanol was 2.6%. The enrichment factor was 167. The developed method was used to determine total phosphate content in surface waters. The reliability of the proposed methodology was tested with the use of samples spiked with a known concentration of the determined element and by comparative inductively coupled plasma‐optical emission spectrometry. The recovery (in the range of 93.5–97%) was satisfactory and indicates usefulness of the developed procedure.

A novel ultrasensitive phosphate amperometric nanobiosensor based on the integration of pyruvate oxidase with highly ordered gold nanowires array.

A novel phosphate amperometric nanobiosensor, based on an intimate integration of pyruvate oxidase (PyOx) and its cofactors, thiamine pyrophosphate (TPP) and flavin adenine dinucleotide (FAD), with a highly ordered gold nanowires array (AuNWA) has been developed. The successful integration of PyOx and the co-factors, via crosslinking with bovine serum albumin (BSA) and glutaraldehyde (GLA), onto the AuNWA was confirmed by cyclic voltammetry and amperometry. The resulting nanobiosensor achieved a detection limit of 0.1 µM, a linear concentration range of 12.5-1000 µM, and a sensitivity of 140.3 µA mM(-1)cm(-2). Notably, the incorporation of the AuNWA reduced the required PyOx concentration by 70-120 fold and the presence of common interferants, such as chloride, sulfate, fluoride, nitrite and nitrate ions did not interfere with phosphate detection. Furthermore, the nanobiosensor demonstrated a very high stability with repeated use over two weeks and was successfully used for the determination of phosphate in water samples with an average recovery of 96.6 ± 4.9%.

Screen-printed electrode modified with carbon black nanoparticles for phosphate detection by measuring the electroactive phosphomolybdate complex

We report a sensor for phosphate detection based on screen-printed electrodes modified with carbon black nanoparticles. The phosphate was measured in amperometric mode via electrochemical reduction of molybdophosphate complex. Carbon black nanoparticles demonstrated the ability to quantify the molybdophosphate complex at a low applied potential. Some analytical parameters such as the working solution (sulfuric acid 0.1M), applied potential (0.125V vs Ag/AgCl), and molybdate concentration (1mM) were optimized. Using these conditions, a linear range of 0.5–100µM was observed with a detection limit of 0.1µM, calculated as three times the standard deviation of the blank divided by the slope of calibration curve. The system was challenged in drinking, river, aquarium, and waste water samples yielding satisfactory recovery values in accordance with a spectrophotometric reference method which demonstrated the suitability of the screen-printed electrode modified with carbon black nanoparticles coupled with the use of molybdate to detect phosphate in water samples.

Application of solidification of floating organic drop microextraction for inorganic anions: Determination of phosphate in water samples

A novel dispersive liquid–liquid microextraction based on solidification of a floating organic drop (DLLME-SFO) for determination of orthophosphate was developed. The method includes the formation of molybdoantimonatophosphoric heteropoly blue (HPB) followed by a DLLME-SFO procedure and subsequent absorbance measurement using a micro volume cell (5μL) with 10mm path length. The final experimental conditions for HPB extraction were found to be: 0.6mL of ethanol as dispersive solvent containing 55μL of 1-undecanol as extraction solvent, magnetic stirring at 500rpm, 10min extraction time, decreasing the stirring rate to 150rpm in order to group all the droplets and then solidification of the organic droplet in an ice bath for 5min under continuous magnetic stirring. It should be pointed out that no centrifugation step is required. The calibration plot was linear in the range 4.0–60×10−8molL−1 of phosphate, with a correlation coefficient of 0.9982. The limit of detection (LOD), calculated as three times the standard deviation of the blank test (n=10), was 7.4×10−9molL−1 of phosphate. The reported procedure was applied for determination of phosphate in real water samples.

Amino-functionalized Nano-size Composite Materials for Dispersive Solid-Phase Extraction of Phosphate in Water Samples

An efficient analytical method for the preconcentration and determination of phosphate in water samples at trace levels was proposed. The method was based on sample enrichment using dispersive solid-phase extraction (dSPE) with tetraethylenepentamine (TEPA)-functionalized nano-size composite materials (TEPA-NCMs) as sorbents, which were fully characterized. Various parameters affecting the extraction efficiency were systematically investigated. After extraction, the post-adsorbed TEPA-NCMs were eluted by a NaOH solution for desorption of the phosphate. The resulting eluate containing phosphate was determined by a spectrophotometric method. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.29 and 0.96 μg L(-1), respectively. The relative standard deviations (RSDs) were lower than 8.0% with average recoveries ranging from 91 to 118%. The present method was successfully applied to the determination of phosphate at trace levels in real water samples, and it was confirmed that the TEPA-NCMs are highly effective dSPE materials.

Determination of Phosphate in Water Samples of Nashik District (Maharashtra State, India) Rivers by UV‐Visible Spectroscopy

The major rivers of Nashik District (Maharashtra State, India) are Godavari, Kadawa, Girna, Punad and Mosam. The major water pollutant of Nashik District Rivers is Phosphate. The amount of phosphate has been determined by the molybdenum blue phosphorous method in conjugation with UV‐Visible Spectrophotometer. The data has been analyzed by least square method. The more phosphate polluted river in Nashik district is Godavari. The least phosphate polluted river in Nashik District is Punad.

Competitive Sorption between Oxalate and Phosphate in Soil: An Environmental Chemistry Laboratory Using Ion Chromatography

A laboratory experiment was developed to introduce students to an important chemical phenomenon, anion sorption and desorption in the soil. In this lab exercise, competitive sorption between oxalate and phosphate was evaluated on aluminum oxide and a soil from a temperate region. Testings were done at two pH levels using a batch equilibrium technique. Ion chromatography was used for simultaneous measurement of oxalate and phosphate in water samples collected from the experiment. The results from this experiment clearly illustrated that oxalate exudation by the roots of certain plants may help them obtain phosphorus in phosphorus-deficient soils. Students gained hands-on experience in ion chromatography and knowledge about important chemical factors affecting the behavior of anions in the soil environment and their potential effects on plants. This lab exercise would be appropriate for use in undergraduate or master-degree courses in chemistry, environmental chemistry, and instrumental analysis.

Spectrophotometric determination of phosphate in waters of Egypt

The proposed method is used for determination of trace amounts of phosphate in water samples especially of Dakahlia Governorate. The recommended procedure is based on the formation of molydophosphoric acid which upon, selective reduction with the reducing agent oxalyldihydrazide produces a blue color due to the molybdenum blue. The intensity of the blue color is proportional to the amount of phosphate initially incorporated in the heteropoly acid. The resulting blue complex could be determined in the range of 2.25 to 22.46 μg P with molar absorptivity of 33418 L−1 mol−1 cm−1 at 880 nm. The reduction of phosphomolybdate complex by oxalyldihydrazide is chosen in the work and the result is compared with those obtained with the reducing agent potassium antimonyl tartrate, the reduction methods are frequently recommended for manual analysis of waters and wastes for P.

The Spectrophotornetric Determination of Inorganic Phosphate in Egypt Water using Resazurine and Para-rosolic acid

Abstract A sensitive method for rapid determination of inorganic phosphate in water samples is described which is based on a reaction between phosphomolybdate and resazurine; phosphomolybdrlte and p-rosolic acid. The molar absorptivities are 2867.5, 2656.9 at 495 and 470 nm with resazurine and p-rosolic acid reagents. Phosphate can be determirled in concentration range of 0.02 to 0.08 ppm, of 0.02 to 0.16 ppm with resazurine and p-rosolic acid reagents respectively.

Determination of trace amounts of phosphate in water samples by ion-exchange resin thin-layer spectrophotometry

A simple but highly sensitive method for determining trace amounts of phosphate in water has been developed. The method involves concentrating molybdenum blue in a thin layer prepared from a finely divided anion-exchange resin and measurement of the absorbance of the coloured layer. The dependence of the absorbance on the concentration of sulphuric acid and ammonium molybdate resulting from the procedure for producing molybdenum blue was reduced by adding gelatin to the sample solution. The calibration graph deviated slightly from linearity and the relative standard deviation was 1.95%(n= 4) for 0.5 µg of phosphate. This method was applied to the determination of trace amounts of phosphate in several water samples.

The colorimetric determination of phosphates in water at low p.p.m. levels by automatic discrete-sample analysis

Two colorimetric methods based on the formation of molybdenum blue (the tin(II)and ascorbic acid methods) have been adapted for the routine automatic determination of phosphate in water samples. Repeatability and linearity of both methods in discrete-sample automatic analysis are satisfactory. Some water samples were analyzed by both methods to compare final analytical results. An analytical rate of 60 readings per hour can be obtained.