Fluoride standard solution

Materials Required Doxycyline Hydrochloride 0.30 g oxygen-combustion flask 1 L capacity Nessler cylinder 100 ml zirconyl alizarin solution 5.0ml fluoride standard solution(10ppmF)(dilute... 

Prescribed Limit The colour of the resulting solution is greater than that obtained by repeating the operation with no substance enclosed in the successive portions of filter paper burnt in the method for oxygen flask combustion, but adding 3.0 ml of fluoride standard solution (10 ppm F) to the combined absorption liquids before adding the acid zirconyl alizarin solution. ... 

Fluoride Determine as directed in Method IV under Fluoride Limit Test, Appendix IIIB, using a 2-g sample, Buffer Solution A, and 0.1 mL of Fluoride Standard Solution. 

Why is a fluoride-free toothpaste added to the standard solutions ... 

The following data were collected for the analysis of fluoride in tap water and in toothpaste, (a) For the analysis of tap water, three 25.0-mL samples were each mixed with 25.0 mL of TISAB, and the potential was measured with an F ISE relative to a saturated calomel electrode. Five 1.00-mL additions of a standard solution of 100.0-ppm F were added to each, measuring the potential following each addition. 

Discussion. In mixtures of magnesium and manganese the sum of both ion concentrations may be determined by direct EDTA titration. Fluoride ion will demask magnesium selectively from its EDTA complex, and if excess of a standard solution of manganese ion is also added, the following reaction occurs at room temperature ... 

A mixture of tin(IV) and lead(II) ions may be complexed by adding an excess of standard EDTA solution, the excess EDTA being determined by titration with a standard solution of lead nitrate the total lead-plus-tin content of the solution is thus determined. Sodium fluoride is then added and this displaces the EDTA from the tin(IV)-EDTA complex the liberated EDTA is determined by titration with a standard lead solution. 

Pipette 25 mL of solution B into a 100 mL beaker mounted on a magnetic stirrer and add an equal volume of TISAB from a pipette. Stir the solution to ensure thorough mixing, stop the stirrer, insert the fluoride ion-calomel electrode system and measure the e.m.f. The electrode rapidly comes to equilibrium, and a stable e.m.f. reading is obtained immediately. Wash down the electrodes and then insert into a second beaker containing a solution prepared from 25 mL each of standard solution C and TISAB read the e.m.f. Carry out further determinations using the standards D and E. 

Plot the observed e.m.f. values against the concentrations of the standard solutions, using a semi-log graph paper which covers four cycles (i.e. spans four decades on the log scale) use the log axis for the concentrations, which should be in terms of fluoride ion concentration. A straight line plot (calibration curve) will be obtained. With increasing dilution of the solutions there tends to be a departure from the straight line with the electrode combination and measuring system referred to above, this becomes apparent when the fluoride ion concentration is reduced to ca 0.2 mg L-1. 

Elemental composition H 5.04%, F 94.96%. The total acidity of an aqueous HF solution may be measured by titration with a standard solution of base using phenolphthalein or another suitable color indicator. Alternatively, the end point may be determined by potentiometric titration. The fluoride ion may be analyzed using a fluoride ion-selective electrode or by ion chromatography. The HF gas may be analyzed by GC/MS using a GC column having... 

Oxygen difluoride may be analyzed by GC, GC/MS, IR, and NMR methods. The compound may be identified by GC/MS, the characteristic mass ions are 54, 38 and 35. The compound can be measured quantitatively by wet methods based on its strong oxidizing ability (see Reactions). It liberates I2 from an acidified solution of potassium iodide and the liberated I2 can be measured by iodometric titration using Na2S20s titrant and starch indicator. Alternatively, the compound may he treated with a measured amount of excess NaOH and the unreacted excess NaOH measured hy titrating against a standard solution of HCl. Also, the fluoride ion, F, may he measured by fluoride selective electrode. 

A bare surface of silicon can only exist in fluoride containing solutions. In reality, in these media, the electrode is considered to be passive due to the coverage by Si— terminal bonds. Nevertheless, the interface Si/HF electrolyte constitutes a basic example for the study of electrochemical processes at the Si electrode. In this system, the silicon must be considered both as a charge carrier reservoir in cathodic reactions, and as an electrochemical reactant under anodic polarization. Moreover, one must keep in mind that, according to the standard potential of the element, both anodic and cathodic charge transfers are involved simultaneously (corrosion process) in a wide range of potentials. 

When a fluoride electrode was immersed in standard solutions (maintained at a constant ionic strength of 0.1 M with NaN03), the following potentials (versus S.C.E.) were observed ... 

Using an expanded scale pH meter, such as the Orion 801, pipet 10 ml of the stock solution into a small beaker and add 10 ml of Tisab (Orion No. 94-09-09). Determine the electrode potential using a fluoride electrode Orion 94-09. Comparison is made by bracketing with fluoride standards prepared similarly. 

Prepare a standard calibration curve using fluoride standards from 0 to 1.5 mg F /L. A 50-mL volume of standard solutions is treated with 10 mL of zirconyl-... 

Oikawa and Saitoh [89] reported studies of the application of ion chromatography to the determination of fluoride, chloride, bromide, nitrite, nitrate, sulphate, sulphite and phosphate ions in 3 ml samples of rainwater. The results show that the most suitable eluent for this purpose is 2m mol L 1 sodium carbonate/5m mol L 1 sodium hydroxide. The reproducibility of the determination was satisfactory for standard solutions of all the ions except nitrite. This problem was solved by preparing standard and sample solutions with the same composition as the eluent. 

Standard Solution Dissolve an accurately weighed quantity of USP Sodium Fluoride RS quantitatively in water to obtain a solution containing 1.1052 mg/mL. Transfer 20.0 mL of the resulting solution into a 100-mL volumetric flask containing 50 mL of Buffer Solution, dilute to volume with water, and mix. Each milliliter of this solution contains 100 p,g of fluoride ion. 

Standard Response Line Transfer 50.0 mL of Buffer Solution and 2.0 mL of hydrochloric acid into a beaker, and add water to make 100 mL. Add a plastic-coated stirring bar, insert the electrodes into the solution, stir for 15 min, and read the potential, in millivolts. Continue stirring, and at 5-min intervals, add 100 (xL, 100 xL, 300 xL, and 500 jxLof Standard Solution, reading the potential 5 min after each addition. Plot the logarithms of the cumulative fluoride ion concentrations (0.1, 0.2, 0.5, and 1.0 (xg/mL) versus potential, in millivolts. 

Buffer Solution, Standard Solution, and Electrode System Prepare as directed under Fluoride in the monograph for Calcium Phosphate, Dibasic. 

Electrode Calibration Pipet 50 mL of the Buffer Solution into a plastic beaker. Place the fluoride ion and reference electrodes (or a combination fluoride electrode) into the plastic beaker and stir. At 5-min intervals, add 100 pL and 1000 pi. of the 1000 mg/kg Fluoride Standard and read the potential, in millivolts, after each addition. The difference between the two readings is the slope of the fluoride electrode and should typically be in the range of 54 to 60 mV at 25°. If the difference in potential is not within this range, check, and, if necessary, replace the electrode, instmment, or solutions. 

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