Determination Of Phosphorus In Water Research Articles

Determination of phosphorus by phosphorus molybdenum blue spectrophotometry by bismuth antimony sensitization

ABSTRACT. The determination of phosphorus in rain water is of great significance. In this paper the optimum conditions of phosphorus molybdenum blue spectrophotometric method for the determination of phosphorus content were obtained. At the maximum absorption wavelength 690 nm, the apparent molar absorptivity is ε690 nm = 1.44 × 104 L·mol-1·cm-1. Beer’s law is followed over the range of 0.02-1.8 μg·mL-1 for phosphorus(V) content. Bismuth(III) and antimony(III) as the sensitizer has a sensitization effect on the phosphomolybdenum blue photometry. The addition of both simultaneously increases the sensitivity by 71.3%. The present method has been used for the determination of phosphorus in water samples. The recovery of method is between 99.20 - 100.1% and the relative standard deviation is between 1.31-1.33% for eleven determination. The results determined by the present method were in agreement with those of atomic absorption spectrometry. This method can avoid the harm of organic reagent to human body and to environmental pollution without organic solvent extraction. This method does not need heating with room temperature color development. Compared with other methods, it has the advantages that the operation is simple, fast and the sensitivity is high.
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1307-1313. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i6.1

Determination of phosphorus in water using iron hydroxide assisted laser-induced breakdown spectroscopy

Phosphorus (P) in water could be selectively detected using iron hydroxide assisted laser-induced breakdown spectroscopy.

Determination of phosphorus in water and chemical fertilizer samples using a simple drawing microfluidic paper-based analytical device.

A simple one-step drawing for the cost-effective fabrication of microfluidic paper-based analytical devices (µPADs) for the determination of phosphate content in water and fertilizer samples is presented in this paper. The hydrophobic barrier of µPAD was patterned using a 2-mm tip marker pen using a transparent acrylic sheet template. The molybdenum blue reaction using ascorbic acid as a reducing agent was used. A pre-concentration step of samples is proposed to improve the sensitivity of the measurement. The blue complex produced on the µPADs was recorded using a smartphone camera. The color intensities (red, green, blue and gray) were analyzed using ImageJ program. The proposed µPAD method provides a linear calibration range from 0 to 100mg L-1 P. The limit of detection (LOD) was found to be 0.7mg L-1 P with a precision of 3.1%RSD for 50mg L-1 P (n = 10). The proposed method was successfully applied to the determination of phosphorus contents in water and liquid chemical fertilizer samples. The results obtained from µPAD agreed with a spectrophotometric method using paired t test at a 95% confidence level.

Cobalt(III) Oxidation Pretreatment of Organic Phosphorus Compounds for a Spectrophotometric Determination of Phosphorus in Water

Cobalt(III) oxidation was applied to the decomposition of organic phosphorus compounds as a pretreatment of a spectrophotometric determination of organic phosphorus. A cobalt(III) solution (ca. 0.16mol dm-3), prepared through the electrolysis of a 0.2mol dm-3 cobalt(II) sulfate solution containing 5mol dm-3 sulfuric acid, was mixed with a sample solution containing a phosphorus compound at a volume ratio of 1:5, and allowed to stand for oxidation. After excess cobalt(III) ions had been reduced to cobalt(II) ions with ascorbic acid, the concentration of phosphate ions in the sample solution was determined by Molybdenum Blue spectrophotometry at 880nm. The cobalt(III) ions could completely convert the mg dm-3 level of phosphorus of organic compounds having a C-O-P or C-P bond into phosphate ions through the treatment within 10min at room temperature, and did not interfere with the subsequent determination. Although phosphonic and phosphinic acids could be oxidized by cobalt(III) ions, condensed phosphates required heating at 95-100°C during the cobalt(III) treatment for complete hydrolysis. Since the present method was free from any interference from coexisting organic and inorganic substances, except at a relatively high level of reducing substances, it is applicable to organic phosphorus determinations in real water samples.

Application of organic solvent-soluble membrane filters in the preconcentration and determination of trace elements: spectrophotometric determination of phosphorus as phosphomolybdenum blue

A simple and rapid preconcentration technique, based on collecting trace elements on a membrane filter and dissolving the membrane filter in an organic solvent, has been applied to the spectrophotometric determination of phosphorus in water. Phosphorus, 0.5–7 μg in 50–500 ml of water sample, is collected as phosphomolybdenum blue on a nitrocellulose or acetylcellulose membrane in the presence of n-dodecyltrimethylammonium bromide, the membrane is dissolved in 5 ml of dimethyl-sulphoxide (DMSO), and the absorbance of the DMSO solution is measured at 710 nm against a reagent blank. Moderate concentrations of silicate, anionic and non-ionic surfactants and high concentrations of sodium chloride do not interfere. Interference from arsenate can be eliminated by reducing the arsenate to arsenite. Condensed and organic phosphates can be determined if they are first converted into orthophosphoric acid by digestion with persulphate. The limit of determination is 0.002 μg of phosphorus in 100 ml of sample.

A semiautomated procedure for the determination of phosphorus in water, waste waters and particulates

Improved procedures for the determination of total dissolved phosphorus (TDP), particulate phosphorus (PP) and dissolved inorganic orthophosphate (DP) are described. Organic particulate material is solubilized in 5 n NaOH, and phosphorus compounds are oxidized and mineralized to orthophosphate by persulfate digestion. DP is determined by an improved automated molybdenum blue procedure that does not require sample pH adjustment or a correction for silicate interference in the 0–50 mg Si 1 −1 range. The use of 36-position digestion racks allows 32 TDP or PP samples to be digested in ca. 1 and 4 h respectively. Detection limits in μg of phosphorus 1 −1 are DP, 2; TDP, 5; and PP. 1. Waste water samples were analyzed for TDP and PP by the nitric acid-sulfuric acid procedure and by the proposed method. There was no significant difference between the two sets of data (P > 0.45).