Standard Phosphate Solution

Barium Sulphate To 1.0 g add a mixture of 3 ml 2M HNOs and 7 ml DW, heat on a water-bath for 5 minutes, filter, dilute the filtrate to 10 ml with DW, add 5 ml molybdovanadic reagent and allow to stand for 5 minutes. Any yellow colour produced is not more intense than that of a standard prepared simultaneously and in the same manner using 10 ml of phosphate standard solution (= 5 ppm P04) (50 ppm). 

Phosphate Evaporate 400 mg of sample to dryness on a steam bath. Dissolve the residue in 25 mL of approximately 0.5 N sulfuric acid, add 1 mL of ammonium molybdate solution [500 mg of (NH4)5Mo7024 4H20 in each 10 mL of water] and 1 mL of p-methylaminophenol sulfate TS, and allow it to stand for 2 h. Any blue color does not exceed that produced by 2.0 mL of Phosphate Standard Solution (20 pig PO4) (see Solutions and Indictors) in an equal volume of solution containing the quantities of the reagents used in the test. Residue on Evaporation Evaporate 25 g of sample to dryness in a tared porcelain or silica dish on a steam bath, and... 

Phosphate Standard Solution (10 pig P04 in 1 mL) Dissolve 143.3 mg of monobasic potassium phosphate (KH2P04) in water in a 100-mL volumetric flask, dilute to volume with water, and mix. Transfer 10.0 mL of this solution into a 1000-mL volumetric flask, dilute to volume with water, and mix. 

Transfer 20 /xl, 50 /xl, and 100 /xl of your extracted lipid sample in CHCI3 to three 4-ml glass vials with Teflon-lined screw caps. Transfer 0.30 ml of a 1 /xmol/ml phosphate standard solution to a fourth 4-ml glass vial. 

Prepare a series of phosphate standard solutions in 4-ml glass vials using the 0.3-ml sample of phosphate (1 /rrnol/ml) prepared on Day 2. 

Phosphate standard solution—Dissolve 13.8 mg of NaH2P04 H20 in 100 ml of distilled water. 

Figure 5, Recorder signals obtained with the manifold shown in Figure 4. The blank solution is artificial seawate (7). The remaining solutions were natural seawater containing —0.9 /xM PO4 to which phosphate standard solution...

Worked example 4. A confluence flow injection system with a very low confluent stream flow rate is designed for the spectrophotometric determination of phosphate in plant digests. The linearity of the analytical calibration graph is good and the recorded absorbance corresponding to a 100.0 mg L 1 P (as phosphate) standard solution is 0.21. Replacing the sample carrier stream by this standard solution (sample infinite volume) yields a steady state situation and the related absorbance is 0.68. The pump is then turned off and an asymptotic increase in absorbance towards 0.95 is observed determine the sensitivity improvement that in principle could be attained simply by increasing the sample volume and the mean sample residence time in the analytical path. 

To 100 ml of the soluhon prepared (neutralized as prescribed if necessary), 4 ml of sulphomolybdic reagent R3 is added. The solution is shaken and 0.1 ml of stannous chloride solution R1 is added. A standard is prepared in the same manner using 2 ml of phosphate standard solution (5 ppm PO ) R and 98 ml of water R. After 10 min, compare the colors using 20 ml of each soluhon. Any color in the test soluhon should not be more intense than that in the standard. 

Phosphate standard solution Potassium dihydrogen phosphate, KH2PO4 (relative molecular mass 136.09), is dried in an oven at 110 °C, then placed in a desiccator. Exactly 136.09 mg are dissolved in pure water to which has been added 0.2 mL of sulphuric acid (reagent 1) and made up to 100 mL. Stored cold in a glass bottle the solution is stable for months. This standard stock solution contains 10 mmol/L phosphate. 

Prepare phosphate standards in the range of 0-160 nmol phosphate using 0-400 pL of the phosphate standard solution which should be pipetted into glass test tubes. 

The spectrophotometric method recommends using standard solutions of phosphate in the range of 2-10 ppm, whereas the FIA method recommends standards in the range of 10-60 ppm. Explain why the methods use a different range of standards. 

In the FIA method we measure the absorbance before the reduction of the yellow-colored Mo(VI) complex is complete. For this reason, the absorbance for any standard solution of phosphate will always be smaller when using the FIA method. This means that the FIA method is less sensitive, and higher concentrations of phosphate are necessary. 

Silver compounds, available from commercial suppHers, are expensive. Reagent grades of sHver(I) carbonate, cyanide, diethjldithiocarbamate, iodate, nitrate, oxide, phosphate, and sulfate are available. Standardized solutions of silver nitrate are also available for analytical uses. Purified grades of sHver(I) acetate, bromide, cyanide, and iodide can be purchased silver nitrate is also made as a USP XX grade for medicinal uses (6). 

Assay of pholasin. Two different methods have been used. In the first method, light intensity or total light emission is measured when a standard solution of luciferase is added to a pholasin sample (Henry et al., 1970). In the second method, total light emission is measured when 1 ml of a degassed solution of 0.3 mM FeSC>4 is injected into 2 ml of 0.15 M phosphate buffer, pH 7.0, containing a pholasin sample and 0.75 M NaCl (Michelson, 1978). The luminescence reaction is complete within 2 or 3 min. 

The specifications and standardization include raw materials, preparation method of the standard solution, concentration of proteins, and the main band on SDS-PAGE. The outline of the procedure for preparation of the calibrators is shovm in Eig. 4.2. Table 4.5 shows the raw materials and the preparation method of the initial extract. To prepare the calibrators, the raw materials are extracted by the standard solution containing SDS and mercaptoethanol. The initial extract is prepared by centrifugation and filtration of the extract. The diluted extract is then prepared by 10-fold dilution of the initial extract with phosphate-buffered saline (PBS pH 7.4). The protein concentration of the diluted extract is assayed using the 2-D Quant kit (Amersham Bio Sciences). The standard solution is then... 

Procedure Separately inject into the chromatograph equal volumes (about 20 pL) of the solution under the test and a Standard solution having a known concentration of USP primaquine phosphate RS in the same Medium and record the chromto-grams. Measure the responses for the major peak, and calculate the amount of C15H21N3O2H3PO4 dissolved. 

Rao et al. [46] reported the use of a spectrophotometric method for the determination of primaquine phosphate with ninhydrin. Standard solution of 0.01% primaquine phosphate solution (3 mL) or solution prepared from the drug or its tablets was mixed with 2 mL of water, 5 mL of 2-methoxyethanol and then with 4 mL of ninhydrin reagent. The mixture was boiled for 35 min, and, after cooling and dilution to 25 mL with water, the absorbance was measured at 570 nm versus a reagent blank. Beer s law was obeyed from 4 to 20 pg/mL with recoveries of 99.4— 100.2% for 25 mg of primaquine phosphate. 

Competitive immunoassays may also be used to determine small chemical substances [10, 11]. An electrochemical immunosensor based on a competitive immunoassay for the small molecule estradiol has recently been reported [11]. A schematic diagram of this immunoassay is depicted in Fig. 5.3. In this system, anti-mouse IgG was physisorbed onto the surface of an SPCE. This was used to bind monoclonal mouse anti-estradiol antibody. The antibody coated SPCE was then exposed to a standard solution of estradiol (E2), followed by a solution of AP-labeled estradiol (AP-E2). The E2 and AP-E2 competed for a limited number of antigen binding sites of the immobilized anti-estradiol antibody. Quantitative analysis was based on differential pulse voltammetry of 1-naphthol, which is produced from the enzymatic hydrolysis of the enzyme substrate 1-naphthyl phosphate by AP-E2. The analytical range of this sensor was between 25 and 500pg ml. 1 of E2. 

The reference standard solution is prepared by dissolving about 35 mg. accurately weighed erythromycin standard in 100 ml. methanol in a 250 ml. volumetric flask. This is diluted with phosphate buffer pH 7.0 to 250 ml., mixed, and allowed to cool to room temperature, then again diluted to the mark and mixed well. 

How to analyze the phosphate counterion of a known active pharmaceutical compound (API), primaquine diphosphate, is shown as an example. A simplified method was used to demonstrate the feasibility of the method. For this purpose, we prepared three sample solutions and three standard solutions each at 70%, 100%, and 130% of the expected value. Octanoic acid was chosen as internal standard. 

Suitable conditions for the quantitative polarographic determination of technetium as pertechnetate are given by Miller et al. who propose a 0.1 M KCl solution of pH 10 or a phosphate buffer solution of pH 7. Since in pH 7 buffer the current is directly proportional to the concentration of technetium over the range of 0.1 to 1.1 ppm, this medium has been used for the determination of low concentrations of technetium in solutions of fission products by the standard addition technique. The half-wave potential of the used wave is —0.68 V vs. SCE. The reaction appears to be irreversible (Fig. 13). It has been found that neither rhenium, ruthenium nor other fission products interfere. However, tetraphenyl-arsonium chloride is reduced at a more positive potential than is pertechnetate therefore, (QH5) AsCl, if present, must be separated. 

Sulphate stock standard solution, 500 pg mM of SO -S - dissolve 2.717 g potassium sulphate (K SO ), previously dried at 105°C for 1 h and cooled in a desiccator, in calcium phosphate extractant, then transfer to a 1-1 volumetric flask with washings and make up to the mark with extractant. 

Sulphate working standard solutions, 0-12 pg mM of SO -S - pipette 1, 2, 4, 6, 8 and 12 ml of the 500 pg mh sulphate stock standard solution into 500-ml volumetric flasks, make up to the mark with calcium phosphate extractant and mix. This will give solutions containing 1, 2, 4, 6, 8 and 12 pg mh of sulphate-S. 

Stock standard solution, 2000 pg N mh 200 pg P mM, 1600 pg K mb, (400 pg Ca mb ) - omit the Ca if it is unlikely to be required, so as to avoid the precipitation of calcium sulphate in the diluted standards. This combined standard solution can be used for the autoanaiysis of P and K, and also provides a similar matrix to the sample digests. Each reagent should be dried at 102°C for 1 h and cooled in a desiccator before weighing. Dissolve 1.3745 g potassium chloride, 0.4393 g potassium dihydrogen phosphate, 4.7162 g ammonium sulphate, (and 0.5000 g calcium carbonate), in sulphuric acid (approximately 98% m/m H SO ) and make up to 500 ml with sulphuric acid. 

Biochemical oxygen demand (BOD) is one of the most widely determined parameters in managing organic pollution. The conventional BOD test includes a 5-day incubation period, so a more expeditious and reproducible method for assessment of this parameter is required. Trichosporon cutaneum, a microorganism formerly used in waste water treatment, has also been employed to construct a BOD biosensor. The dynamic system where the sensor was implemented consisted of a 0.1 M phosphate buffer at pH 7 saturated with dissolved oxygen which was transferred to a flow-cell at a rate of 1 mL/min. When the current reached a steady-state value, a sample was injected into the flow-cell at 0.2 mL/min. The steady-state current was found to be dependent on the BOD of the sample solution. After the sample was flushed from the flow-cell, the current of the microbial sensor gradually returned to its initial level. The response time of microbial sensors depends on the nature of the sample solution concerned. A linear relationship was foimd between the current difference (i.e. that between the initial and final steady-state currents) and the 5-day BOD assay of the standard solution up to 60 mg/L. The minimum measurable BOD was 3 mg/L. The current was reproducible within 6% of the relative error when a BOD of 40 mg/L was used over 10 experiments [128]. 

The total free chlorine in wastewaters as measured by colorimetric techniques constitutes both the dissolved molecular chlorine, hypochlorite ion, OCl, and hypochlorous acid. An equilibrium exists between these species, the concentrations of which depend on the temperature and pH of the waste-water. Concentration of the hypochlorous acid may be estimated from the K value or from the ratio (33% of the measured concentration of free chlorine). The free chlorine may be measured by amperometric titration after the addition of a phosphate buffer solution to produce a pH between 6.5 and 7.5. The sample is titrated against a standard solution of phenylarsine oxide. Alternatively, the syringaldazine (3,5-dimethoxy-4-hydroxybenzaldazine) colorimetric test may be performed. This color-forming reagent in 2-propanol yields a colored product with free chlorine, the absorbance of which may be... 

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