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.

Highly sensitive determination of dissolved ultra-trace phosphorus by ICP–MS with methane mixed plasma

Phosphorus concentrations in water are usually determined using phosphomolybdenum blue (PMB) spectrophotometric. However, the measurement of extremely low phosphorus concentrations by this method is limited for various reasons, making it...

Spectrophotometric Determination of Low Levels of the Orthophosphate Anion as Molybdenum Blue using Sodium Thiosulphate Reducing agent

A simple spectrophotometric method for the determination of low levels of the orthophosphate (PO43-) in environmental water systems is reported. The method is based the formation of the phosphomolybdate from the condensation of molybdate and orthophosphate in aqueous acid medium followed by reduction with sodium thiosulphate to form phosphomolybdenum blue. The system obeys Beer’s law at 880 nm (λmax) in the 0.005–0.06 mg P mL-1 phosphate concentration range. Molar absorptivity, Sandell’s sensitivity and correlation coefficient values for the determination were 57526 L mol-1 cm-1, 0.2835 μg cm-2 and 0.9948 respectively. The limit of detection was 2.213 x 10-3 mg P mL-1. The results of PO43- determination in water samples obtained using the spectrophotometric method developed in this study, compare favourably with those generated using the Murphy and Riley method which is commonly used for this analysis. Therefore, the study ably demonstrates the suitability of the present spectrophotometric method for analysis of the orthophosphate in environmental water samples.

Sebaran Fosfor Anorganik Partikulat (PIP) di Muara Sungai Banjir Kanal Barat Semarang

Muara Sungai Banjir Kanal Barat Semarang merupakan wilayah yang berpotensi mengalami eutrofikasi akibat buangan limbah rumah tangga dan industri. Sebagian besar penelitian sebelumnya lebih berfokus pada fosfor dalam sedimen dasar dan fosfat terlarut, sedangkan kandungan fosfor anorganik dalam total suspended solid (TSS) di perairan muara dan laut menerima lebih sedikit perhatian. Tujuan dari penelitian ini adalah mengetahui sebaran fosfor anorganik partikulat (PIP) di perairan sekitar muara Sungai Banjir Kanal Barat Semarang. Pengambilan sampel dilakukan pada lapisan permukaan (kedalaman 0,5 m). Analisis TSS dilakukan dengan metode gravimetri. Ekstraksi asam PIP dilakukan berdasarkan metodologi ekstraksi konvensional, menggunakan 1 M HCl, diikuti oleh prosedur untuk menurunkan keasaman dan dianalisis dengan metode spectrophotometric phosphomolybdenum blue pada panjang gelombang 880 nm. Konsentrasi PIP yang didapatkan berkisar antara 0,42 µmol/g – 1,28 µmol/g dengan nilai rata-rata sebesar 0,54 µmol/g. Sebaran PIP dipengaruhi oleh arus pasang surut, total suspended solid (TSS) dan salinitas. Sebaran PIP dominan ke arah barat – barat laut karena pengaruh arus pada saat pasang menuju surut. Konsentrasi PIP menurun seiring berkurangnya konsentrasi TSS dan meningkatnya nilai salinitas. Banjir Kanal Barat estuary is an area that has the potential to experience eutrophication due to household and industrial waste disposal. Most previous research has focused more on phosphorus in basic sediments and dissolved phosphate, whereas the inorganic phosphorus content in total suspended solid (TSS) in estuarine and marine waters received less attention. The purpose of this study was to determine the distribution of particulate inorganic phosphorus (PIP) in the waters around the Banjir Kanal Barat estuary. Sampling was carried out on the surface layer (0.5 m depth). TSS analysis was performed using the gravimetric method. PIP acid extraction was carried out based on conventional extraction methodology, which required 1 M HCl, followed by a procedure to reduce acidity and analyzed by spectrophotometric phosphomolybdate blue method at a wavelength of 880 nm. PIP concentrations obtained ranged from 0,42 µmol/g – 1,28 µmol/g with an average value of 0.54 µmol/g. Distribution of PIP is influenced by tidal currents, total suspended solid (TSS) and salinity. Distribution of PIP is dominant to west – northwest direction due to the influence of currents at ebb current. PIP concentration decreases with decreasing TSS concentration and increasing salinity.

Phosphomolybdenum Blue Detection – A Review of Characteristics, Achievements, Challenges and Future Prospects

Phosphate detection in the environment (especially, water bodies) is very essential in view of its consequent pollution effects on eutrophication. Continuous monitoring of phosphate concentration (and phosphorus compounds in general) in water samples has been based on phosphomolybdenum blue formation coupled with spectrophotometric detection. Continu­ous flow injection analyses (FIA) are well known to present numerous advantages over batch methods. Furthermore, the development of on-chip micro-channel analytical (μFIA) systems begun and have gained much attention within the last two decades in view of the striking advantages over conventional FIA techniques. This paper reviews published information on detection of phosphomolybdenum blue in conventional systems as well as on micro-chip. It reports on the challenges encountered (interference from other complex anions), the achieve­ments made so far (intereference removal by electrokinetic separation) and what the future holds (simultaneous determination).

Spectrophotometric Determination of Phosphate in Sugarcane Juice, Fertilizer, Detergent and Water Samples by Molybdenum Blue Method

A simple and sensitive spectrophotometric method has been developed for the determination of phosphate in mg per liter (parts per million) concentration range in sugarcane juice, water, fertilizer and detergent samples. The amount of phosphate is determined by molybdenum blue phosphorus method in conjugation with UV-visible spectrophotometer. This method is based on the formation of phosphomolybdate complex with the added molybdate followed by the reduction of the complex with hydrazine hydrate in aqueous sulphuric acid medium. The system obeys Lambert-Beer’s law at 840 nm in the concentration range 0.1-11 ppm. The colour intensity of the reduced phosphomolybdate solution is found to be proportional to the amount of phosphate present in sugarcane juice, water, fertilizer and detergent samples. The reaction conditions as well as the various experimental parameters affecting the development and stability of the coloured complex were carefully investigated and optimized for the quantitative determination of phosphate present in various samples. The optimized concentrations of various reagents used are 0.20N sulphuric acid, 0.02M hydrazine hydrate and 0.20% ammonium molybdate. The effect of time on the formation of phosphomolybdenum blue complex and addition of the order of the reagents was also studied. Scientific World, Vol. 11, No. 11, July 2013, page 58-62DOI: http://dx.doi.org/10.3126/sw.v11i11.9139

Thermal Assisted UV Digestion Utilizing Nano-TiO2 Photocatalyst for the Detection of Total Phosphorous

This work presents a novel thermal assisted ultra-violet (UV) photocatalysis oxidation method for total phosphorus (TP) detection. A 365nm wavelength UV light was used as the UV light source, and the TiO2 particles, immobilized on silicon wafer, were used as the catalyst. The sodium glycerophosphate was digested as the typical compound of TP. The digested samples were determined by spectrophotometry after the phosphomolybdenum blue reaction. The catalyst can be used repetitively with long-term stability in this work. For the photocatalysis digestion process under room-temperature, when the reaction time reached 120min, the conversion rates were 92.31% and 93.66% for 1mg/L and 4mg/L of C3H7Na2O6P solutions, respectively. And conversion rates were 95.48% and 99.37% respectively for thermal assisted ultra-violet (UV) photocatalysis digestion process at the condition of 30min and 60°C. Compared with the conventional thermal digestion method and photocatalysis digestion method for TP detection, this thermal assisted UV digestion method can greatly decrease the digestion time and enhance the efficiency.