Applikationer

Determination of chloride and sulfate in the presence of high nitrate concentrations. Optimization of the chromatographic separation by variation of the temperature and eluent composition.

A potentiometric, nonaqueous method is described for analyzing nitrating acid using cyclohexylamine as titrant. Both sulfuric and nitric acid can be determined quantitatively.

Sulfate can be rapidly and easily titrated thermometrically using a standard solution of Ba2+ as titrant. In industry, the widespread procedure is applied to the determination of sulfate in wet-process phosphoric acid.

Determination of sodium, ammonium, potassium, calcium, and magnesium in 4% boric acid using cation chromatography with direct conductivity detection.

Determination of magnesium, cadmium, and iron in phosphoric acid using cation chromatography with direct conductivity detection.

Tafel analysis is an important electrochemical technique used to understand reaction kinetics. By studying the Tafel slope, it reveals the rate-determining steps in electrode reactions, aiding fields like corrosion and fuel cell research. This method helps industries optimize processes and improve device performance by tailoring materials and conditions for greater efficiency.

The study of the electrochemical behavior of platinum in acidic media is of crucial importance in fundamental electrochemistry and electrocatalysis. Most electrocatalytic processes occurring at Pt electrodes are highly sensitive to the structure of the platinum surface. Cyclic voltammetry (CV) is a widely used rapid measurement technique that provides both a qualitative and quantitative fingerprint of platinum surfaces. A comparison of results given by linear and staircase CVs is presented in this Application Note.

Many different configurations are made possible when using two-, three-, or four-electrode cell setups in research. Depending on the experimental requirements, one setup may be preferred over another. Therefore, the proper electrode arrangements for these three situations are defined in this Application Note. As an example, the potential at the counter electrode is measured during the platinum oxidation in acidic media, with the second sense (S2) of VIONIC powered by INTELLO. Since dissolved Pt in solution could bias the results, it is important to be able to monitor the potential of the counter electrode.

In this Application Note, hydrogen permeation experiments are conducted following the procedure described in the ASTM standard G148.

The Devanathan-Stachurski cell (or «H cell») is successfully used to evaluate the permeation of hydrogen through sheets or membranes. As small amounts of hydrogen pass through the sheet or membrane, a very sensitive potentiostat is required for its detection. A study of the hydrogen permeation properties of different iron sheets is discussed in this Application Note while taking the instrumental requirements into account.

This Application Note presents a walkthrough of an experiment on 4-nitrothiophenol using hyphenated EC-Raman, a combination of Raman spectroscopy and electrochemistry.

Determination of the sulfate content of wet process phosphoric acid.

This Application Note explains how fluoride determination in acid etching baths can be performed with thermometric titration.

Determination of sulfate and total acids in a nitrating mixture.

Determination of hydrofluoric acid in mixed acid etchant solutions.

Automated determination of the H2SiF6 and HF contents of industrial grade hexafluorosilicic acid.

This Application Note describes the determination of fluoride in silicon etch solutions with thermometric titration.

Determination of the total acids concentration in mixtures of nitric-hydrofluoric acid intended for etching silicon substrates.

A sample of concentrated mineral acid is dissolved in anhydrous acetonitrile, and the water content titrated with a solution of TEOF in acetonitrile. The TEOF reacts exothermically with water in the presence of a strong acid (acting as a catalyst).

Results from three separate single endpoint titrations are used to calculate the results. The mixture of H2SO4, HF, and NH4F/HF contains H+ from H2SO4, HF, and NH4F/HF, SO42- from H2SO4, and F- from HF and NH4F/HF. Analysis of total H+ («total acids») by NaOH titration, F- by titrating with Al(NO3)3 («total fluoride») and SO42- by titrating with BaCl2 provides the information required to determine the composition of the mixture.

Two separate titration sequences are required to analyze the mixture:- titration of the HF content with Al(NO3)3 (the «elpasolite» reaction)- titration of the H2SO4 with BaCl2 followed by titration with NaOH to determine the «total acids» contentThe HF, H2SO4, and «total acids» contents are converted to a HNO3 equivalent, with the HNO3 content found by subtracting the HF and H2SO4 from the «total acids» content.

A direct thermometric titration (TET) with 2 mol/L NaOH is used to determine the HF, NH4F, and maleic acid (C4H4O4) contents of acid cleaning solutions. Three endpoints (EPs) are obtained, which may be assigned as follows:EP1: C4H4O4 (pKa1 = 1.9), HF (pKa = 3.17)EP2: C4H4O4 (pKa2 = 6.07)EP2: NH4F (pKa = 8.2)The HF content is determined by subtracting the difference (EP2-EP1) from EP1.

This Application Note supplements AN-H-003 with the treatment of the standard addition of sulfate as sulfuric acid. This technique may be contemplated when either sulfate levels are too low for a satisfactory direct titration, or when the sample matrix hinders endpoint detection, leading to poor precision and accuracy.

The presence of the hydrated ion [Fe(H2O)6]3+ can interfere with the determination of «free acid» due to the low pKa value (~2.2) of this ion. Ions of metals such as Fe, Cu, and Al can be masked effectively with fluoride, and permit the determination of the acid content by thermometric alkalimetric titration with good accuracy and precision.

This Application Note deals with the determination of ferric ion in acidic and copper-free solutions using thermometric titration. The ferric ion is reduced by iodide. The released iodine reacts exothermically when titrated with thiosulfate solution. The endpoint is determined through temperature plotting by the temperature sensor Thermoprobe.

This Application Note describes the determination of aluminum ion down to approximately 0.5 g/L in acidic solutions containing ferric, ferrous, and other ions whose hydroxides do not dissolve in strongly basic solutions.

This Application Note looks at the determination of ferrous ion in acidic solutions from approximately 0.25 g/L by thermometric titration with ceric titrant. The exothermic oxidation reaction shows a sharp endpoint that is detected using the Thermoprobe as a sensitive temperature sensor.

This Application Note looks at the determination of ferrous ion in acidic solutions through redox titration with potassium permanganate as titrant and thermometric titration.

Thermometric titration is used for the determination of hydrochloric acid and nitric acid in acid baths. The entire acid content is titrated with caustic soda in the initial titration; the hydrochloric acid content is then determined in a second titration using silver nitrate solution.

Determination of NO3- and ClO4- in the presence of a large excess of HCl using anion chromatography with direct conductivity detection (using time program for full scale change after 18 min).

Determination of traces of iodide in HCl (25%) using anion chromatography with amperometric detection at a silver electrode.

Determination of traces of bromide in HCl (32%) using anion chromatography with amperometric detection at the silver electrode.

Boric acid is growing in demand for various industrial applications, but requires a more cost-efficient and environmentally friendly production process. This Application Note describes the performance of a Raman process analyzer (PTRam) when measuring low-concentration boric acid and sodium sulfate solutions (<100 mg/L) during boric acid production.

Fentanyl, a powerful synthetic opioid, is illegally distributed worldwide. Overdosing can be fatal, causing symptoms like stupor, pupil changes, cyanosis, and respiratory failure. Just 2 mg of fentanyl can be lethal, depending on factors like body size and past usage. Given its severe impact, identifying and detecting fentanyl is crucial, as it has become a major public health crisis. Combining electrochemical surface-enhanced Raman spectroscopy (EC-SERS) with screen-printed electrodes (SPEs) offers a fast, effective, and precise method for detecting fentanyl.

Determination of phosphate and tetrafluoroborate in 2% HF using anion chromatography with conductivity detection after chemical suppression.

Determination of traces of chloride in a technical product using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride, chloride, phosphate, and sulfate in boric acid using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride, chloride, nitrate, phosphate, and sulfate in boric acid with sample preconcentration using anion chromatography with conductivity detection after chemical suppression.

Determination of sulfate in methansulfonic acid (70%) using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride and sulfate in hypophosphoric acid using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride in concentrated nitric acid using anion chromatography with conductivity detection and chemical suppression.

Determination of chloride, nitrate, and sulfate in 85% H3PO4 using two-dimensional anion chromatography with conductivity detection after sequential suppression.

Determination of fluoride, chloride, and nitrate in concentrated sulfuric acid (96…98%) using anion chromatography with conductivity detection after sequential suppression.

Electronic-grade nitric acid may not contain more than the slightest traces of anion contaminations (in the mg/L range). The ion chromatography determination of these kinds of anion traces requires not only a high-capacity column but also an eluent that allows the nitrate to be eluted by the column, although only after all of the other ions of interest have been eluted. This separation is achieved on a column of the Metrosep A Supp 16 - 250/4.0 type with the aid of a strong carbonate/hydrogen carbonate eluent.

Spectroelectrochemical experiments not only provide outstanding qualitative information about samples, but also offer other quantitative data that can be considered when performing analyses. A single set of experiments allows analysts to obtain two calibration curves: one with the electrochemical data and another with the spectroscopic information. The concentration of tested samples is calculated by using both curves, confirming the obtained results by two different routes. In this Application Note, comparison between electrochemical and spectroscopic determinations demonstrates that the two methods measure uric acid (UA) indistinctively, with close agreement of the calculated values with empirical data.

The development of a novel reflection cell for conventional electrodes facilitates the performance of spectroelectrochemical measurements. This device allows researchers to work in aqueous solutions as well as in organic media due to its chemical resistance.

Hydrochloric acid is a strong, inorganic mineral acid with great significance in the chemical industry. The potentiometric titration of hydrochloric acid with sodium hydroxide is one of the most important and also most frequent analyses performed in the laboratory. In this Application Note, an acid-base titration is presented where the concentration of HCl is determined with NaOH using a pH electrode with an integrated Pt1000 temperature senor for the most accurate results

Phosphoric acid is a triprotic inorganic acid used for many purposes: as a raw material for the production of phosphate fertilizers, detergents, as an electrolyte in phosphoric acid fuel cells, rust removers, and for the passivation of iron and zinc to protect against corrosion. This Application Note presents an acid-base titration where the concentration of phosphoric acid is determined over all three of its dissociable protons by titrating it with sodium hydroxide.

Determination of aluminum in phosphoric acid using cation chromatography with UV detection after post-column reaction with catechol violet.

Determination of aluminum in an acidic extract containing metals (e.g., alkali, alkaline earth, iron, chromium, molybdenum, etc.) using cation chromatography with UV detection after post-column reaction with Tiron.