Water Phosphate Research Articles

Risk assessment and identification of factors influencing the historical concentrations of microcystin in Lake Taihu, China

Understanding the history of microcystins (MCs) pollution in large lakes can help inform future lake management. We collected sediment cores from Lake Taihu to: investigate the long-term record of MCs (MC-LR, MC-YR, and MC-RR), explore the main environmental drivers of MCs, and assess their public health and ecological risks. Results showed that MCs content in all cores increased over time. The core from north Taihu had the highest MC concentrations, with an average total MCs (sum of MC-LR, MC-YR, and MC-RR = TMCs) content of (74.31±328.55) ng/g. The core from eastern Taihu showed the lowest average TMCs content of (2.91±3.95) ng/g. PCA showed that sediment MCs at the three sites were positively correlated with sediment chlorophyll-a. MC-LR and MC-YR in northern and western Taihu negatively correlated with both the sediment total organic carbon/sediment total nitrogen ratio (STOC/STN) and water nitrate (NO3−-N) concentration, but three MC congeners at eastern Taihu showed positive correlations with water orthophosphate (PO43−-P), NO3−-N, and STOC/STN. Generalized additive model analysis at each site revealed that NO3−-N was the main TMCs driver in northern and western Taihu where phytoplankton dominated, whereas PO43−-P was the main TMCs driver in eastern Taihu where macrophytes dominated. At the whole lake scale, total phosphorus (TP) and PO43−-P were the most important environmental drivers influencing MCs; TP explained 47.4%, 44.2%, and 47.6% while orthophosphate explained 34.8%, 31.2%, and 34.7% of the deviance on TMCs, MC-LR, and MC-YR, respectively. NO3−-N also showed a strong effect on MCs variation, especially on MC-YR. Risk assessment showed that both ecological and public health risk has increased in recent years. We conclude that while control of phosphorus and nitrogen input should be a major focus for future lake management, lake zone-specific management strategies may also be important.

Colorimetric determination of trace orthophosphate in water by using C18-functionalized silica coated magnetite

In this study, we customized magnetic sorbents by functionalizing silica coated magnetite with octadecyl(C18)silane (Fe3O4@SiO2@C18). This sorbent was intended for the determination of trace orthophosphate (o-PO43−) in unpolluted freshwater samples. The o-PO43− was transformed to phosphomolybdenum blue (PMB), a known polyoxometalate ion. Then the PMB were coupled with cetyl trimethyl ammonium bromide (CTAB), cationic surfactant, in order to hydrophobically bound with the Fe3O4@SiO2@C18 particles through dispersive magnetic solid-phase extraction (d-MSPE) as part of sample preconcentration. The PMB–CTAB–magnetic particles are simply separated from the aqueous solution by the external magnet. The acidified ethanol 0.5 mL was used as PMB-CTAB eluent to produce an intense blue solution, which the absorbance was measured using a UV–Vis spectrophotometer at 800 nm. The proposed method (employing 2 mg of Fe3O4@SiO2@C18) yielded an enhancement factor of 32 with a linear range of 1.0–30.0 µg P L−1. Precision at 6.0 µg P L−1 and 25.0 µg P L−1 were 3.70 and 2.49% (RSD, n = 6) respectively. The lower detection limit of 0.3 µg P L−1 and quantification limit of 1.0 µg P L−1 allowed trace levels analysis of o-PO43− in samples. The reliability and accuracy of the proposed method were confirmed by using a certified reference material. Our method offers highly sensitive detection of o-PO43− with simple procedures that can be operated at room temperature and short analysis time.

Optimization of Conditions for Determination of Orthophosphate in Water by Molybdenum-Antimony Anti-Spectrophotometry

Optimization of Conditions for Determination of Orthophosphate in Water by Molybdenum-Antimony Anti-Spectrophotometry

Synthesis and characterization of stable lead (II) orthophosphate nanoparticle suspensions

There is great interest in producing nanoparticles for various applications. The objective of this work was to develop a procedure for reproducibly creating stable lead (Pb) phosphate nanoparticle aqueous suspensions. A stable 5 mg/L Pb-phosphate nanoparticle “stock” suspension was synthesized via chemical precipitation of Pb and orthophosphate in water at pH 7.5 with 4.4 mg soluble PO4/L and 7 mg C/L dissolved inorganic carbon. The stock suspension was subsequently diluted to produce stable 0.10 mg/L Pb “challenge” water suspensions without compromising the nanoparticle size, structure, mineralogy and solubility. Specifically, the hexagonal hydroxypyromorphite nanoparticles had an average diameter of 38 nm based on transmission electron microscopy analysis and an associated Pb solubility of 0.001 mg/L. The properties of the stock suspensions were not impacted by further dilutions, and the challenge water suspensions remained stable for 24 hours. In the context of drinking water, a protocol to produce such a stable Pb nanoparticle challenge water suspension would be very useful in evaluating Pb bioavailability, identifying Pb remediation strategies, and testing filter effectiveness to remove Pb from water.

Determination of potential genotoxic impurity hydrazine hydrate in ibrutinib by RP-liquid chromatography

A sensitive, simple, rapid and robust reverse phase HPLC method was developed for the determination of Potential genotoxic impurity Hydrazine hydrate in Ibrutinib by using Salicyldehyde as derivatization Reagent and Octadecyl as stationary phase with column dimension of 4.6 mm × 250 mm and 5 µm particle size (Inertsil ODS-3V). 0.02 M Ammonium dihydrogen orthophosphate in water and acetonitrile in the ratio (35:65) was used as mobile phase. Isocratic elution mode was used for the separation, using a flow rate of 1.0 mL/min and column oven temperature of 40 °C. Detection was carried out at wavelength of 354 nm. Developed method is validated as per ICH guidelines and found to be linear, accurate, specific, selective, precise and robust. Test solution was found to be stable up to 48 hrs. This method can be successfully applied for the determination of Hydrazine hydrate in Ibrutinib for routine analysis and stability assessment.

ESTIMATION OF ATOSIBAN ACETATE IN PARENTERALS BY RP HPLC

A simple, precise, rapid and accur a te reverse phase HPLC method was developed for the estimation of Atosiban Acetate in dosage form. A n XTerra MS C18 analytical column ( 250 x 4.6 mm , 5 μm partical size ) with mobile phase consisting of mixture of buffer 0.0 3 M Potassium Dihydrogen Orthophosphate in water and pH adjusted to 3.20 with o rtho - phosphoric acid and acetonitrile in the gradient program was used. The flow rate was 1.0 mL /min an d the effluents were monitored at 2 2 0 nm . The retention time was 1 1.3 min . The detector response was linear in the concentration of 15 - 225 mc g/ mL . The respective linear regression equation being y = 1286.9 x - 1290 . 8 . The limit of detection (LOD) and limit of quantification (LOQ) for Atosiban Acet ate were found to be 1.5 mcg/mL and 4.5 mcg/mL respectively . The percentage ass ay of Atosiban Acetate was 99. 6 %. The method was validated by determining its accuracy, precision and linearity . The results of the stu dy showed that the proposed RP - HPLC method is simple, rapid , precise and accurate, which is useful for the

Fósforo na alimentação de pacu (Piaractus mesopotamicus)

Objetivou-se avaliar o uso de fósforo na dieta de juvenis de pacu (Piaractus mesopotamicus) sobre a qualidade da água, o desempenho zootécnico, o rendimento corporal e a composição química da carcaça. Foram utilizados 100 juvenis com peso médio inicial de 25,9±1,32 g, distribuídos em delineamento inteiramente ao acaso, em 20 tanques de fibra de vidro, com cinco tratamentos e quatro repetições. Os peixes foram alimentados quatro vezes ao dia, às 8; 11; 14 e 17 h, com dietas extrusadas contendo 0,40; 0,55; 0,70; 0,85 e 1,0% de fósforo total. Não foram observadas diferenças nos parâmetros de qualidade de água, com exceção da concentração de ortofosfato na água, que apresentou aumento linear. Os parâmetros de desempenho zootécnico, rendimento corporal e composição química da carcaça não diferiram entre os níveis de suplementação de fósforo na dieta. A utilização de 0,40% de fósforo total atende às exigências de fósforo de juvenis de pacu (Piaractus mesopotamicus), além de disponibilizar menor concentração de ortofosfato da água.

Analytical method development and validation of prasugrel in bulk and its pharmaceutical formulation using the RP-HPLC method

Purpose: This study was designed to develop and validate a simple, sensitive, precise, and specific reverse phase high-performance liquid chromatographic (HPLC) method for the determination of prasugrel in bulk and its tablet dosage forms. Materials and Methods: The HPLC separation was carried out by reverse phase chromatography on an inertsil ODS-3V column (5μm; 250×4.6mm2) with a mobile phase composed of 0.02M potassium dihydrogen orthophosphate, 0.02M dipotassium hydrogen orthophosphate in water:acetonitrile (30:70v/v) in isocratic mode at a flow rate of 1ml/min. The detection was monitored at 210nm. Results: The calibration curve for prasugrel was linear from 100 to 600μg/ml. The inter-day and intra-day precision was found to be within limits. The proposed method has adequate sensitivity, reproducibility, and specificity for the determination of prasugrel in bulk and its tablet dosage forms. The limit of detection and limit of quantification for prasugrel were found to be 0.25μg/ml and 0.75μg /ml, respectively. Accuracy (recoveries: 99.8-101.2%) and reproducibility were found to be satisfactory. Conclusion: The proposed method is simple, fast, accurate, and precise for the simultaneous quantification of prasugrel in the dosage form, bulk drugs as well as for routine analysis in quality control.

A Validated Rapid Stability-Indicating Method for the Determination of Related Substances in Solifenacin Succinate by Ultra-Fast Liquid Chromatography

A rapid, sensitive, and accurate ultra-fast liquid chromatographic method is developed for the determination of related substances and degradants of Solifenacin Succinate, an active pharmaceutical ingredient used in the treatment of overactive bladder. Chromatographic separation of Solifenacin Succinate, its related substances, and degradants was achieved using a Shimpack XR-ODS-II column and mobile phase system containing 10 mM potassium dihydrogen orthophosphate in water. The pH of the buffer was adjusted to 7.0 using triethyl amine (mobile phase A). LC-grade acetonitrile was used as mobile phase B, employing a binary-gradient program at a flow rate 0.5 mL/min. The resolution between the critical pair of peaks (Impurity A and analyte) was found to be greater than 3.5. The limits of detection and quantification (LOQ) of Impurity A, Impurity B, and the analyte were 0.2 and 0.6 μg/mL, respectively for a 5-μL injection volume. The percentage recovery of impurities in the presence of sample matrix ranged from 95 to 104 w/w. The test solution and mobile phase was observed to be stable up to 24 h after the preparation. The validated method yielded good results of precision, linearity, accuracy, robustness, and ruggedness. The proposed method is found to be rapid, accurate, and suitable for the quantitative determination of related substances and degradants during quality control of Solifenacin Succinate active pharmaceutical ingredient.

Sediment Raking as a Tool for Enhancement of Phosphate and Productivity of Water in Tropical Pond System

Changes of orthophosphate in water, induced by raking of surface sediment in various ways, were compared. Twelve limnocorrals were installed in a shallow mesotrophic pond using four treatments with triplicate replication:(1) raking of surface sediment (R) by means of a rake for 5min per week (2) fish (F), by introducing six common carp and two silver carp per limnocorral, (3) raking plus fish (R+F) and (4) control (C), without raking and fishless. After day 122, treatments were reversed in limnocorrals by␣removing (netting) or introducing fish and stopping or initiating raking. Samples of water and sediment were collected from each limnocorral at weekly interval and monitored for orthophosphate (OP), primary productivity, phosphate solubilizing bacteria (PSB) and sediment available phosphorus. Raking in presence of fish caused 280 and 160% increase in OP concentrations in surface and bottom water, respectively, as compared with raking in absence of fish. Net effects of fish and raking were 13-81 and 26-241%, respectively in surface water and 48-100 and 46-95% in bottom water. This implied that in bottom water, net raking effect was 13-161% greater than net fish effect. Increase in PSB population, due to raking plus␣fish (R+F) was 6-82% higher than increase by fish alone (F). Responses of available-P in sediment were opposite to that of water, being highest in concentration in control (C) followed by fish (F), raking (R) and raking plus fish (R+F). The primary productivity showed variations parallel with that of orthophosphate of water. This suggests that raking accelerated the transformations of available-P from␣sediment to overlying water mediated through oxygen-dependent sediment water exchange mechanisms.

Flow-through solid-phase based optical sensor for the multisyringe flow injection trace determination of orthophosphate in waters with chemiluminescence detection

In this work, a novel flow-through solid-phase based chemiluminescence (CL) optical sensor is described for the trace determination of orthophosphate in waters exploiting the multisyringe flow injection analysis (MSFIA) concept with multicommutation. The proposed time-based injection flow system relies upon the in-line derivatisation of the analyte with ammonium molybdate in the presence of vanadate, and the transient immobilisation of the resulting heteropolyacid in a N-vinylpyrrolidone/divinylbenzene copolymer packed spiral shape flow-through cell located in front of the window of a photomultiplier tube. The simultaneous injection of well-defined slugs of luminol in alkaline medium and methanol solution towards the packed reactor is afterwards performed by proper switching of the solenoid valves. Then, the light emission from the luminol oxidation by the oxidant species retained onto the sorbent material is readily detected. At the same time, the generated molybdenum-blue compound is eluted by the minute amount of injected methanol, rendering the system prepared for a new measuring cycle. Therefore, the devised sensor enables the integration of the solid-phase CL reaction with elution and detection of the emitted light without the typical drawbacks of the molybdenum-blue based spectrophotometric procedures regarding the excess of molybdate anion, which causes high background signals due to its self-reduction. The noteworthy features of the developed CL–MSFIA system are the feasibility to accommodate reactions with different pH requirements and the ability to determine trace levels of orthophosphate in high silicate content samples (Si/P ratios up to 500). Under the optimised conditions, a dynamic linear range from 5 to 50 μg P l −1 for a 1.8 ml sample, repeatability better than 3.0% and a quantification limit of 4 μg P l −1 were attained. The flowing stream system handles 11 analysis h −1 and has been successfully applied to the determination of trace levels of orthophosphate in environmental samples such as mineral, ground, tap and pond waters as well as samples from a water-steam cycle of an incineration plant. The t-test comparison of the means for the developed optical sensor and the molybdenum-blue spectrophotometric APHA/AWWA/WPCF reference method revealed that there is no evidence of significant differences between the obtained results at the 95% confidence level.

Sequential injection standard addition system with a mixing chamber: determination of orthophosphate in waters

Sequential injection standard addition system with a mixing chamber: determination of orthophosphate in waters

Low-Cost Colorimetric Measurement of Phosphate Trace Levels in Water and in Soil Solutions by the Collinear Photothermal Beam Deflection Method

Abstract The collinear photothermal beam deflection technique with a c.w. AlGaAs semi-conductor diode laser (790nm) and He-Ne laser (630 nm) used as the pump and probe beam, respectively, has been combined with the molybdenum blue colorimetry to measure the level of orthophosphate in water and in soil solutions. A detection sensitivity of 0.1 mmol/m3 of PO3- 4 has been achieved with the present set-up.

Determination of orthophosphate in waters and soils using a flow analyser

A high-performance continuous flow analyser has been used for the determination of orthophosphate ion in potable waters and soil extracts by the heteropolymolybdenum blue method. Interference from a number of common ionic species has been examined and found to be small at the levels encountered in potable waters. The limit of detection for PO43– was calculated to be 14.5 p.p.b. (4.8 p.p.b. of P), a linear calibration range of up to 0–100 p.p.m. was demonstrated and the sample throughput was better than 120 samples h–1 using the calibration range 0–4 p.p.m. and above, and 50 samples h–1 using the range 0–0.5 p.p.m.

Analytical determination of orthophosphate in water

Analytical determination of orthophosphate in water

Untersuchungen zur Gleichwertigkeit von Analysenverfahren ? Flie�injektionsanalyse und DIN-Verfahren bei der Orthophosphatbestimmung in Oberfl�chenw�ssern

The German standard method for the determination of orthophosphate in water, waste water and sludge, laid down in the norm DIN 38405, part 11, is based on the absorbance measurement of the phosphormolybdic acid after reduction with ascorbic acid. In order to apply a more rapid method, flow injection analysis was used following a procedure published in the Tecator application note ASN 60/83. It is also based on the formation of molybdenum blue employing stannous chloride as reducing agent. The equivalence of both analytical methods is examined by statistical tests according to the norm DIN 38402, part 71. It is shown that no unequivocal assertion can be given because the examination is based on the selection of one sample only and the decision depends on the number of repeated determinations performed for the sample.

Solvent Extraction-Spectrophotometric Determination of Trace Orthophosphate in Water by Stopped-Flow Time Difference Analysis Technique

For the determination of phosphate from μg l-1 to sub-μg l-1 level in water, the time difference analysis technique (a sort of end-point assay using the stopped-flow method) was used by combining the Molybdenum Blue method and the pre-concentrating solvent extraction of 12-molybdophosphate. Isobutyl alcohol and stannous chloride were used as the solvent and the reductant, respectively. The reducing reaction was fast and the colored complex formed by the reaction was unstable. Phosphate concentration was easily determined by analyzing the reaction curves recorded for only 0.5s. The apparent molar absorptivity of phosphate was about 2×105M-1 cm-1 at 730nm, and the detection limit was 0.3μg l-1. The calibration curve was linear from zero to 5μg l-1. The method was applied to the determination of phosphate in tap water samples; the relative standard deviation was less than 3% and the recovery of 20μg l-1 phosphate was 100±6%.

Spectrophotometric determination of phosphorus as orthophosphate based on solvent extraction of the ion associate of molybdophosphate with malachite green using flow injection

Phosphorus as orthophosphate in water was determined by a spectrophotometric method involving flow injection coupled with solvent extraction. The ion associate formed between molybdophosphate and Malachite Green was extracted into benzene-4-methylpentan-2-one (1 + 2 V/V) and the absorbance was measured at 630 nm. The carrier stream was 0.005 M sulphuric acid and the reagent stream contained ammonium molybdate, Malachite Green and sulphuric acid. A newly designed phase separator was used to separate the organic phase. The sampling rate was 40 samples per hour. Calibration graphs were linear below 30 ng ml–1 and below 1 µg ml–1 of phosphorus on injecting samples of 300 and 10 µl, respectively. The detection limit was 0.1 ng ml–1 of phosphorus. Phosphorus in river water was determined satisfactorily by the proposed method.

Atomic absorption spectrophotometric determination of total phosphorus and orthophosphate in water and its application to underground water.

A simple and sensitive method for the determination of total phosphorus and orthophosphate in water was established by using atomic absorption spectrophotometry with a graphite furnace atomizer, and the method was applied to underground water samples. The proposed method is based on the atomic absorption spectrophotometric determination of molybdenum in a chelate complex produced by the reaction of orthophosphate with the molybdate reagent used in a spectrophotometric method. When the recoveries and coefficient values were estimated by applying this method to potassium dihydrogenphosphate as a standard compound in various kinds of water, they were within the range of 96.7-109.0% and below 6.1%, respectively, which are satisfactory. Since the proposed method is highly sensitive (detection limit : 0.0005 mg/l), a time-consuming concentration procedure of water samples could be omitted. When the proposed method and the spectrophotometric method described in the Official Gazette were applied to various kinds of water, a highly significant correlation (r=0.999) was observed between the two. The assayed values of total phosphorus in samples of underground water obtained from 77 stations situated in the southern area of Hyogo prefecture in Japan were distributed between 0.001 and 2.318 mg/l. The concentrations of total phosphorus in the underground water were confirmed to be influenced by the depth of the well, and there was a significant relationship between the concentration of total phosphorus in underground water and the degree of sewerage diffusion.

Rapid separation of soft drinks ingredients using high performance liquid chromatography

A method is described which uses high performance liquid chromatography in the reverse phase mode to separate amaranth, quinoline yellow, quinine sulphate, sunset yellow, caffeine, aspartame, saccharin, vanillin, sorbic acid, benzoic acid and green S in 4 min in samples of soft drinks. The final separation was achieved using 17·5% acetonitrile, 12·5% methanol, 70% buffer (0·85% v/v sulphuric acid and 17·5% m m potassium dihydrogen orthophosphate in water with the pH adjusted to 1·8), with a flow rate of 1·35 ml/min through a 100 mm × 4·6 mm column containing 3 μm Spherisorb octylsilane. The octylsilane material is fully capped with monolayer coverage and a carbon loading of 6% w/w, pore diameter of 8 nm and a surface area of 220 m 2 /g. This material was used in preference to the more widely used octadecylsilane as it provides shorter analysis time and allows for the use of more polar eluting solvents. Detection was at 220 nm, 0·1 AUFSD with an injection of 5 μl samples using a rotary injection valve. The standard solution concentration was 100 mg litre − 1 for aspartame; 20 mg litre − 1 for quinine sulphate, caffeine, vanillin, sorbic acid and benzoic acid and 5 mg litre − 1 for amaranth, quinoline yellow, sunset yellow, green S, tartrazine, indigo carmine and carmoisine.