Determination Of Total Phosphorus Research Articles

Spectrophotometric Determination of Total Phosphorus in Fresh Water Using Ammonium Molybdate

Spectrophotometric Determination of Total Phosphorus in Fresh Water Using Ammonium Molybdate

Validation of a small-scale method for determination of phosphorus in meat and meat products by molecular absorption spectroscopy

The purpose of this study was to evaluate the applicability of an alternative analytical technique to the reference method for phosphorus detection in meat and meat products established by ISO 2294:1974, revised by ISO 23776:2021. When an analytical method is modified or a new one is developed and implemented, it should be validated before being accepted for routine determinations. Furthermore, it is necessary to demonstrate that the new or alternative method has good performance characteristics in comparison with the reference method. Therefore, a comparison of the performance of the alternative and the reference method should be made. In the present study, a statistical evaluation of the calibration model of the alternative method was made with data from interlaboratory studies made in five consecutive years using fifty analyses of meat and meat products. The statistical parameters evaluated over time for the calibration curve were the y-intercept and slope; correlation and linearity; analytical limits: detection and quantification; working range; and accuracy (precision and trueness). In the interlaboratory tests, the results obtained by the alternative analytical method were compared with those obtained by the reference method, and their performance in these tests was also evaluated. The results obtained by the alternative method indicated better accuracy than the reference method due to lower relative errors, more precision, and a good trueness evaluation through lower absolute values of the z-score. The study demonstrated that the phosphorus alternative method is applicable for the determination of total phosphorus in the matrix of meat and meat products.

Large-scale prediction of stream water quality using an interpretable deep learning approach

Deep learning methods, which have strong capabilities for mapping highly nonlinear relationships with acceptable calculation speed, have been increasingly applied for water quality prediction in recent studies. However, it is argued that the practicality of deep learning methods is limited due to the lack of physical mechanics to explain the prediction results of water quality changes. A knowledge gap exists in rationalizing the deep learning results for water quality predictions. To address this gap, an interpretable deep learning framework was established to predict the spatiotemporal variations of water quality parameters in a large spatial region. Mereological, land-use, and socioeconomic variables were adopted to predict the daily variations of stream water quality parameters across 138 sub-catchments in a total of over 575,250 km2 in southern China. The coefficients of determination of chemical oxygen demand (COD), total phosphorus (TP), and total nitrogen (TN) predictions were over 0.80, suggesting a satisfactory prediction performance. The model performance in terms of prediction accuracy could be improved by involving land-use and socioeconomic predictors in addition to hydrological variables. The SHapley Additive exPlanations method used in this study was demonstrated to be effective for interpreting the prediction results by identifying the significant variables and reasoning their influencing directions on the variation of each water quality parameter. The air temperature, proportion of forest area, grain production, population density, and proportion of urban area in each sub-catchment as well as the accumulated rainfall within the previous 3 days were identified as the most significant variables affecting the variations of dissolved oxygen, COD, ammoniacal nitrogen(NH3–N), TN, TP, and turbidity in the stream water in the case area, respectively.

Determination of total nitrogen and phosphorus in soil by ion chromatography with conductivity detector following persulfate digestion method

This study introduces a new method to determine both TP and TN in one process, reducing the analytical cost and time. During this procedure, soil samples were digested in alkaline potassium persulfate (K2S2O8) at 150 °C for two hours in a reactor to convert organic N (including NH3/NH4+) and P species to the highest oxidation states NO3-, PO43-. After that, H2O2 removes the color of the digest, which could influence the efficiency of the analytical process. Finally, ions NO3- and PO43- were separated on the anion-exchange column and quantified by a conductivity detector. According to the spiked samples, which were made by mixing Bovine serum albumin (BSA) with organic nitrogen and triphenyl phosphate containing organic phosphorus with real soil matrix, the recovery of TN and TP was 85% and 97%, respectively. Both TN and TP linear concentration ranges were between 0.50 and 50 µg.mL-1. The results of relative standard deviation and limit of detection for TN were from 4.2%, and 0.31 mg.kg-1; and for TP were from 3.5%, and 0.25 mg.kg-1.

Turbidity as a Surrogate for the Determination of Total Phosphorus, Using Relationship Based on Sub-Sampling Techniques

Turbidity as a Surrogate for the Determination of Total Phosphorus, Using Relationship Based on Sub-Sampling Techniques

Experience in the toothpaste’s hygienic effectiveness assessment by oral fluid biochemical parameters

Relevance. The oral hygiene and prevention quality depends on toothpaste. The literature analysis shows the underuse of saliva biochemical parameters for assessing oral hygiene product effectiveness.Materials and methods. Thirty-three subjects aged 19 to 22 years participated in the study. The participants used four kinds of toothpaste by the same manufacturer to evaluate the toothpaste’s effectiveness. We conducted clinical examinations and collected saliva samples on the 1st, 14th and 28th days of the study. The saliva was collected on an empty stomach without stimulation in the morning. Then it was centrifuged. The supernatant was biochemically studied.Results. The study established the criteria for the toothpaste’s low effectiveness, which involve a signifcant increase in hygienic indices and total antioxidant activity, associated with a statistically signifcant trend towards an increase in lactate content. The criteria for a toothpaste with medium effectiveness are a signifcant decrease in one of the hygienic indices, associated with an alkaline pH shift, and an increase in the total antioxidant activity, without signifcant changes in the lactate content. The criteria for a highly effective toothpaste are a signifcant decrease in hygienic indices, and an alkaline pH shift, associated with a signifcant lactate decrease. Determination of total calcium and inorganic phosphorus in the oral fluid may be crucial for assessing the toothpaste remineralizing properties. The glucose content in mixed saliva yields little information for the toothpaste’s hygienic effectiveness assessment.Conclusion. We can recommend saliva biochemical parameters for assessing the oral hygiene status and the effectiveness of oral hygiene products during oral hygiene product comprehensive studies.

Influence of Chroma and Turbidity on Determination of Total Phosphorus in Surface Water

Influence of Chroma and Turbidity on Determination of Total Phosphorus in Surface Water

Electrochemical impedance sensor based on nano-cobalt-oxide-modified graphenic electrode for total phosphorus determinations in water

In this work, an electrochemical sensor equipped with nano-cobalt-oxide-modified graphenic working electrode is demonstrated for the quantification of total phosphorus through electrochemical impedance spectroscopy (EIS) in water environment. Prior to EIS measurements, phosphorus with various valent ions was electrochemically oxidized to orthophosphate through anodic polarization with graphenic electrode. Orthophosphate specifically binds with nano-cobalt oxide-decorated working electrode, and the generation of Co3(PO4)2 on the modified electrode surface increased the electron transfer resistance, which was characterized by means of EIS. We systematically investigated the impacts of pH, ionic strength, and digestion time on analytical efficiency. Under optimal conditions, a calibration curve is obtained in the linear range of 0.013 to 1.2 mg L−1 with a detection limit (LOD) of 0.013 mg L−1, accompanied by high sensitivity and accuracy exceeding 90% in comparison with National Standard Method, and this proposed method is also well suited for the phosphorus detection in real water sample. Therefore, this designed sensor demonstrated the potential applicability to determine the phosphorus in water environment rather than traditional methods.

Total phosphorus determination in eutrophic tropical river sediments by laser-induced breakdown spectroscopy techniques.

Total phosphorus (TP) in sediments is an important chemical variable in the study of the extent of eutrophication in water bodies. Two methods, based on single pulse (SP) and double pulse (DP) laser-induced breakdown spectroscopy (LIBS), were developed for determining TP in the sediment cores of Brazilian rivers upstream from the Barra Bonita reservoir. TP concentration in the sediments was determined by inductively coupled plasma optical emission spectrometry (ICP OES) on digested samples. Besides, a LIBS system operating in SP and DP modes was used to develop methods for TP quantification in sediment pellets. In LIBS, the most appropriate wavelength to measure P was 214.91 nm. The calibration curves showed correlation coefficients of 0.93 and 0.92 and limits of detection of 709 mg kg-1 and 349 mg kg-1 for SP and DP LIBS, respectively. The two proposed methods were validated and the average percentage errors were 14% and 10% for SP and DP LIBS, respectively. The ICP OES and SP and DP LIBS data showed that the most superficial layers of the Piracicaba River, all the sedimentary layers of the Tietê River, and the confluence region present a high concentration of TP, according to the Brazilian sediment quality criterion. In conclusion, SP and DP LIBS were confirmed as promising alternative tools to traditional analytical methods for monitoring the TP content in the sediments that come from different hydrographic units. The proposed method using DP LIBS proved more sensitive than SP LIBS, but the SP LIBS method demonstrated enough precision for determining TP in eutrophic river sediments.

Water Pollution Control and Treatment Based on Quantum Dot Chemical and Biological High‐Sensitivity Sensing

Inorganic pollutants in water can have an important impact on ecosystems and human health, so the development of rapid and sensitive detection methods for typical inorganic pollutants in water samples is important for understanding the pollution status of the water environment, as well as water pollution prevention and protection of drinking water safety. Fluorescence sensing technology has the advantages of fast response, high sensitivity, simple operation, and low cost but still has the problems of low quantum yield, cumbersome construction process, and limited practical applications. Based on the excellent fluorescence properties, a series of fluorescence sensing was constructed for the rapid, highly sensitive, and selective detection of various typical inorganic pollutants in water. And the related fluorescence sensing mechanism was investigated in this paper. In this paper, nitrogen/sulfur codoped carbon quantum dots (N, S‐CQDs) were prepared for the sensitive and selective detection of sulfide and ferric ion. The blue fluorescent N, S‐CQDs were prepared by a one‐step hydrothermal method using ammonium citrate and L‐cysteine as raw materials, which have excitation wavelength dependence and fluorescence quantum yield of 16.1% for the selective detection of sulfides with a detection limit (S/N = 3) of 11.0 nM (about 0.35 μg/L). CQDs with significantly higher fluorescence quantum yields (69%) and no excitation dependence were prepared when citric acid was used instead of ammonium citrate and were used for the selective detection of ferric ion with a detection limit of 14.0 nM (~0.8 μg/L). The method has been successfully applied to the determination of total phosphorus in surface water and human urine, and the fluorescence color change of the dual‐emission sensing can be used for the naked‐eye identification and semiquantitative detection of phosphate.

Determination of total phosphorus in biodiesel by ion chromatography

Phosphorus content in biodiesel is an important parameter for evaluating its quality. In this paper, the total amount of phosphorus in biodiesel was determined by Ion Chromatography (IC) with on-line matrix elimination function. An effective and safe sample pretreatment method and IC quantification method were adopted. The method has good linear correlation (r = 0.9998), low detection limit (Cmin = 0.007 mg L−1) and reasonable reproducibility. By measuring the residual carbon of biodiesel ashing products at different temperature points as an index of ashing degree, phosphate from biodiesel ashing products at different temperature points was determined by IC; the optimum ashing temperature was 680 °C. At 680 °C, the amount of phosphorus in Jatropha curcas biodiesel was determined by both IC and ICP-OES; the measured phosphorus content was 13.53 mg·kg−1 and 11.25 mg·kg−1, respectively, and exceeded the national standard of 10 mg·kg−1. In addition, the phosphorus content of soybean oil biodiesel was tested by IC at different ashing temperatures. Those results showed that at 680 °C, the biodiesel phosphorus content in soybean oil was 5.41 mg·kg−1, lower than the 10 mg·kg−1 stipulated by ASTM D 6751 and GB 25199, but higher than the 4 mg·kg−1 stipulated by EN14214.

Quantitative determination of phosphorus in seafood using laser-induced breakdown spectroscopy combined with machine learning

Quantitative determination of phosphates or total phosphorus in seafood is of great importance for the fraud detection as well as food security issues. In this work, laser-induced breakdown spectroscopy (LIBS) was applied as a rapid method for phosphorus determination in three types of seafood including codfish, scallop and shrimp. Both univariate and multivariate regression models were established with special attentions on the correction of matrix effect to improve the analytical performances of LIBS. The obtained results showed that compared with the traditional univariate model and the linear PLS model, the non-linear SVM model could provide the best figures-of-merit with R2 of 0.9904, RMSEC, RMSEP and ARE of 1.68 g/kg, 1.42 g/kg and 3.70%, respectively. The average RSD of prediction of SVM is 5.18%, which is much lower than the value of PLS (9.40%) and is comparable to the value of univariate model (4.11%). This indicates that SVM may be more suitable to address the non-linear behaviors in LIBS spectra caused by the matrix effect, and therefore leads to a more robust calibration model. The present results demonstrated the capacity of LIBS combined with machine learning in phosphorus determination of seafood products, which could be potentially used for on-site phosphates detection within the food supply chains.

Determination of phosphorus in different types of waste using the ICP-MS technique

The research aimed to provide an optimized method for the determination of phosphorous concentration in different types of solid waste using inductive coupled plasma mass spectrometry (ICP-MS) technique. The analyzed waste matrices are: a) vegetable waste (P1), b) ash from the incineration of medical waste (P2) c) sewage sludge (P3) and d) sludge from the meat processing industry (P4). The results obtained by the ICP-MS method were compared with the UV-VIS spectrophotometric method for the determination of total phosphorus. In the case of using the colorimetric method by UV-VIS technique, lower results were obtained compared to the ICP-MS method due to the interferences given by the reagents used to determine the total phosphorus. The interferences given by other elements (metals) were also investigated and the performance parameters were determined such as detection limit, quantification limit, recovery and expandend incertainty using ICP-MS technique.

Total Phosphorus Determination in Soils Using Laser-Induced Breakdown Spectroscopy: Evaluating Different Sources of Matrix Effects.

Laser-induced breakdown spectroscopy (LIBS) is a potential alternative to wet chemical methods for total soil phosphorus determination, but matrix effects related to physical and chemical sample properties need to be further understood. The aim of this study was to explore matrix effects linked to particle size distribution and chemical form of phosphorus on LIBS response and the ability of LIBS to predict total phosphorus in a range of different soil types. Univariate calibration curves were developed by spiking the soils with increasing doses of phosphorus, and limits of detection for LIBS determined phosphorous (P) (LIBS-P) were calculated. Different particle size distributions in otherwise identical soils were obtained by four milling treatments and effects of chemical form of phosphorus were examined by spiking soils with identical amounts of phosphorus in different chemical compounds. The LIBS-P response showed a high correlation (R2 > 0.99) with total phosphorus for all soils. Yet, the sensitivity of LIBS differed significantly among soils, as the slope of the calibration curves increased with increasing sand content, resulting in estimated limits of detection of 10 mg kg-1 for the sandiest and 122 mg · kg-1 for the most clayey soils. These limits indicate that quantitative evaluation of total phosphorus in sandy and loamy sandy soils by LIBS is feasible, since they are lower than typical total phosphorus concentrations in soil. A given milling treatment created different particle size distributions depending on soil type, and consequently different LIBS-P results. Thus, procedures that specify the required degree of homogenization of soil samples prior to analysis are needed. Sieving after milling could be an option, but that should be tested. The soils spiked with Fe(III) phosphate, potassium phosphate and phytic acid had similar LIBS-P, except for soils with hydroxyapatite, which resulted in markedly lower response. These results suggested that matrix effects related to the chemical nature of phosphorus would be minor for non-calcareous soils in humid regions, where apatites comprise only a small fraction of total phosphorus. Strategies to overcome matrix effects related to particle size and content of apatite-phosphorus by combining multivariate models and soil type groupings should be further investigated.

Application of total phosphorus sequential injection system in Qingdao coastal area

An integrated system was developed for automatic determination of total phosphorus in seawater based on sequential injection analysis combined with spectrophotometric detection. The experimental parameters of digestion were optimized based on a univariate experimental design. The upper limit of the linear range of the proposed method was 1000 μg/L. The relative standard deviations (RSDs) of accuray were below ±2% (n=3) and the RSD of presicion was 2.18% (n=6). This system has been successfully applied to determine total phosphorus in Qingdao Coastal area. The F test and t test implied the results of the system had no evident difference with those detected by nutrient flow analyzer in the laboratory.

Organic and nutrient removal during start-up period for domestic sewage treatment by an A/O mixed carrier system

This study combined biofilm method and A/O process reasonably to form the biological treatment system. This experiment focused on the performance of the system for domestic sewage according to the determination of CODCr, ammonia nitrogen, total nitrogen, and total phosphorus. The A/O-mixed carrier system had a good removal effect on organic pollutants for simulated domestic sewage. At the start-up period, the average removal rates of CODCr, ammonia nitrogen and total nitrogen were 92%, 90% and 55%, respectively. But the removal effect of total phosphorus was not ideal.

Quantitative Determination of Total-Phosphorus Recovered from Natural Water Bodies Using Iron-Oxidizing Bacteria and Woody Biomass

Quantitative Determination of Total-Phosphorus Recovered from Natural Water Bodies Using Iron-Oxidizing Bacteria and Woody Biomass

Ecosystem history of a tropical reservoir revealed by metals, nutrients and photosynthetic pigments preserved in sediments

Many studies have found evidence of processes of eutrophication and contamination by metals in reservoirs worldwide. The present work discusses the history of changes associated with anthropic impacts in a tropical reservoir (São Paulo, Brazil), using the analysis of metals, nutrients, and pigments in sediment cores. Three cores were obtained in the dam area of the reservoir. One was used for determination of grain size, organic matter (OM), total phosphorus (TP), and total nitrogen (TN). The second core was used for 210Pb dating and analysis of metals (Cr, Cu, Ni, Pb, Zn, Mn, Al, and Fe). The third core was used for analysis of the pigments chlorophyll-a (Chl-a), beta-carotene (Bet), fucoxanthin (Fuc), lutein (Lut), and zeaxanthin (Zea). For the metals, no significant signs of contamination or enrichment were observed. Only Mn presented an increase over time, which was suggestive of increased effluent inflows and erosion processes. Sedimentation rates (SR) tended to increase from the 1990s onwards, which appeared to be due to eutrophication and changes related to land use and occupation in the watershed. In the case of the pigments, there were increases mainly of lutein and zeaxanthin, indicating the presence of Chlorophyta and Cyanobacteria, respectively, associated with eutrophication. Principal component analysis (PCA) was performed, with the first component (PC1) for the deepest layers indicating that they were characterized by the presence of the metals Al, Pb, and Zn (score of −0.89), together with Fe and sand (score of −0.81), which did not indicate enrichment or any significant contamination, hence representing a condition of lower impacts. On the other hand, the upper layers, representing the period from the 1990s onwards, were characterized by variables in PC1 that could be associated with increase of the trophic level (such as Chl-a, score of 0.81) and increased erosive processes (such as SR, score of 0.79). This study helps to address the lack of long-term data for the Broa reservoir and provides information relevant to trophic reconstruction studies of reservoirs using the analysis of photosynthetic pigments. This research helps in identifying recovery targets and could be applied in other contexts, since the impact of eutrophication processes on water bodies is a global scale problem.

Simultaneous Determination of Various Phosphates in Water-Soluble Ammonium Polyphosphate

Based on ion chromatography, this study developed a rapid method for simultaneous determination of linear polyphosphates (PPs) of orthophosphate (P1), pyrophosphate (P2), trimetaphosphate (P3m), tripolyphosphate (P3), tetraphosphate (P4), pentaphosphate (P5), and hexaphosphate (P6) in water-soluble ammonium polyphosphate (WAPP). Investigation indicated that the retention of PPs in column was endothermic and cooling column benefited the elution of PPs. With adjusting the elution mode, eluent (KOH) concentration, gradient time, flowrate, and column temperature, the optimized results were as follows: the injection volume of sample was 1.3 μL, column temperature was 30 °C, and flowrate of the eluent was 1.2 ml min−1. The linear equations for six phosphates are: y = 0.011cP1 + 0.021 (r = 0.9998), y = 0.012cP2 + 0.023, y = 0.011cP3m − 0.013 (r = 0.9997), y = 0.12cP3 + 0.017 (r = 0.9999), y = 0.011cP4 + 0.004 (r = 0.9983), y = 0.011cP5 − 0.082 (r = 0.9962), and y = 0.013cP6 − 0.029 (r = 0.9989), respectively. The determination ranges are: 1–500 mg L−1 for P1, P2, P3m, and P3; and 1–100 mg L−1 for P4, P5, and P6. The recovery is in the range 95–104% for P1, P2, P3m, P3, P4, P5, and P6; the detection limit is in the range 0.17–0.54 mg L−1 and RSDs of intra- and inter-day determination are 0.56–2.51% (n = 5) for seven PPs, and the analysis period is 15 min. The method was consistent with both gravimetric method and molybdenum blue method, while the RSD was in the range 0.61–1.87%. This rapid method can be applied in the determination of total phosphorus and various phosphates in PPs.

A simple phosphorus determination in walnuts and assessment of the assimilable fraction

In this work, a method for the determination of phosphorus in walnuts has been developed due to the fact that there is no specific method for this purpose. A closed-vessel microwave-assisted digestion of the samples was optimized and a modified molybdenum blue spectrophotometric method was carried out with excellent precision and selectivity. To differentiate assimilable and non-assimilable phosphorus, an easy extraction procedure using 1 M NH4Cl was used. FTIR spectra ensured that the phytate extraction was successful. A sampling of thirteen different walnuts available to consumers from different crops and geographical origin was performed. Comparative statistical tools to differentiate walnuts were also carried out. Significant differences based on total content of phosphorus were obtained. Finally, a correlation study between total phosphorus concentration and the non-assimilable fraction showed a non-linear relationship (R2 = 0.435). Therefore, in relation to consumer health the total phosphorus determination must be complemented with information about assimilable phosphorus.