Applications

Tartaric Sulfuric Anodizing (TSA) is an established technique for corrosion protection in the aerospace industry. It is an alternative to the environmentally harmful chromic anodizing process. As such, a method to monitor the levels of sulfuric acid and tartaric acid in TSA plating baths is required. Potentiometric titration methods have been developed, and are widely used across the industry. Their disadvantage is that two titrations with different electrodes and solvents are required.In this Application Note, an alternative method is presented, where the concentration of both acids is determined in sequence using a thermometric sensor. Compared to potentiometric titration, thermometric titration is faster and more convenient (no sensor maintenance required). On a fully automated system, the determination of both parameters takes about 7 minutes.

The thermometric titration method presented here permits a simple and direct determination of the total acid number (TAN) in petroleum products. It is an invaluable alternative to current manual and potentiometric methods. Thermometric titration uses a maintenance-free temperature sensor that does not require rehydration and is free of fouling and matrix effects. The procedure requires minimal sample preparation. Results agree closely with those from the potentiometric titrimetric procedure according to ASTM D664, but the thermometric titration method is far superior in terms of reproducibility and speed of analysis, with determinations being complete in approximately one minute.

The determination of the total causticizer, sodium carbonate and aluminum oxide contents in (Bayer) process liquors can be accomplished with high precision and speed by using the 859 Titrotherm in a thermometric acid-base titration. A complete titration takes approximately 5 minutes.The procedure is an automated adaptation of the traditional Watts-Utley method, and is similar to the VanDalen-Ward thermometric titration method, but with the added advantage that the analysis can also be performed for the carbonate content of the liquor.

This Application Bulletin describes the determination of the total acid number in various oil samples by catalytic thermometric titration as per ASTM D8045.

This Application Note describes the determination of aluminum in samples containing silicon dioxide using thermometric titration and EDTA as the titrant. Excess EDTA is titrated with a Cu2+ solution of known concentration. The initial, uncomplexed Cu2+ ions react immediately with the H2O2 present in the solution, leading to a recognizable sudden increase in temperature.

Hydrogen peroxide solutions can be determined through thermometric endpoint titration (TET) using iodometry. Iodide is oxidized to become iodine, which is then titrated with a standard thiosulfate solution in an exothermic reaction.

Automated thermometric titration of the nickel content of electroless nickel plating solutions. The determination is suitable for fully automated titration employing a 814 Sample Processor.

Metrohm has partnered with industry leaders to develop an alternative standard for the measurement of acid number (AN) in crude oil and petroleum products to overcome shortcomings in the current method (ASTM D664). This new standard method (ASTM D8045) describes the use of thermometric catalytic titration for this analysis. Results agree closely with those from ASTM D664, but the thermometric catalytic titration method is far superior in terms of reproducibility and speed of analysis, with determinations being complete in one minute.Solvent usage is much less compared to older methods, saving on waste disposal cost. Comparison studies show very close data correlation between ASTM D8045 and traditional potentiometric AN titration methods making implementation into a refinery with historic data practical.

Weak, organic bases that are soluble in nonaqueous solvents (including nonpolar solvents) are determined in glacial acetic acid using titration with strong acids, e. g., anhydrous perchloric acid or trifluoromethanesulfonic acid. The endpoint of such titrations can be determined thermometrically, insofar as a suitable thermometric endpoint indicator exists. The exceptional suitability of isobutyl vinyl ether (IBVE) as indicator has been demonstrated.

Boric acid is used in many primary circuits of nuclear power plants, in nickel plating baths, and in the production of optical glasses. Furthermore, boron compounds are found in washing powders and fertilizers. This bulletin describes the potentiometric and thermometric determination of boric acid. The determination also covers further boron compounds, when acidic digestion is applied.

This Application Note describes in detail how to determine the blank value and the titer for thermometric titrations using tiamo™.

Samples of shredded, grated, or sliced cheese are dispersed with a high-speed disintegrator in a solution of trichloroacetic acid, which denatures protein and assists in the liberation of all sodium from the matrix. Toluene is added in a second step of the dispersion process to assist in the solubilization of fat. Ammonium fluoride solution is then added, and the sodium titrated with a titrant comprising 0.5 mol/L Al(NO3)3 and 1.1 mol/L KNO3 to an exothermic endpoint.Na+ + 2K+ + Al3+ + 6F- ↔ NaK2AlF6 ↓In this determination, ammonium fluoride (NH4F) has been found to give sharper endpoints than ammonium bifluoride (NH4F ∙HF). In addition to this application note, you can find more information on thermometric sodium determination in foods in our application video available on YouTube:https://youtu.be/lnCp9jBxoEs

Phosphorus is a primary macronutrient for plants and is a constituent of DNA and adenosine triphosphate (ATP), which is involved in many biological processes requiring energy. In fertilizers, phosphorus is present in the form of phosphate, as the most accessible form of phosphorus for plants is dihydrogen phosphate. Knowledge of the phosphorus content helps to select the right fertilizer for the plants.Traditionally, phosphate is determined gravimetrically (a time consuming procedure) or spectrophotometrically (expensive instrumentation). In this Application Note, an alternative method is presented, where phosphate is determined by a precipitation titration with magnesium. Various solid and liquid NPK fertilizers with phosphorus contents between 6.5 and 17% were analyzed. The analysis by thermometric titration requires no sample preparation in case of liquid NPK fertilizers and only minimal sample preparation in case of solid NPK fertilizers. One determination takes about 5 minutes.

Agriculture at significant scale without fertilizers is no longer possible in the modern world. To grow a sufficient amount of produce for nearly 8 billion people as well as for domesticated animals and industrial uses, fertilizers of different nutrient compositions are available to cater to the unique needs of various soil types. Information on the fertilizer’s composition (e.g., total nitrogen, phosphorus, and potassium) is available to help select the ideal fertilizer for a specific soil. Conventionally these constituents are determined either gravimetrically (e.g., phosphorus, potassium, or sulfate) or with ICP-OES (e.g., phosphorus or potassium). These methods either have the disadvantages of long analysis times combined with laborious sample preparation (gravimetry), or require expensive instrumentation with high running costs (ICP-OES). This White Paper elaborates how thermometric titration is a fast and inexpensive alternative method to provide information on the content of various nutrients in different fertilizers.

Sulfur is a secondary macronutrient for plants and is essential for chloroplast growth and function. In fertilizers, sulfur is usually provided in the form of sulfate. Traditionally the sulfate content is determined gravimetrically by precipitation with barium. The drawback of this method is that it requires numerous time consuming and laborious analysis steps.In this Application Note, an alternative method is presented, where sulfate is determined by a precipitation titration with barium chloride. Various solid and liquid NPK fertilizers with sulfur contents between 1 and 8% were analyzed. The analysis of sulfate in fertilizers by thermometric titration requires no sample preparation at all for liquid NPK fertilizers, and only minimal sample preparation for solid NPK fertilizers. One determination takes about 3 minutes only. To increase the sensitivity of the method, the samples are spiked with a standard sulfuric acid solution, which is then considered when calculating the result.

Thermometric titration can solve application problems that potentiometry cannot solve at all, or at least not satisfactorily.

Thermometric titration is used for the determination of hydrochloric acid and phosphoric acid in acid mixtures. Two endpoints appear on the titration curve that are used for the determination of the two acids.

Thermometric titration is used to determine hydrofluoric acid and nitric acid in etching baths containing ethanol and acetonitrile. Two endpoints appear on the titration curve that are used individually for the quantification of the respective acid.

Thermometric titration can be used for the ready determination of sulfuric acid and phosphoric acid in acid mixtures. An endpoint for each acid appears on the titration curve that can be used to quantify the respective acid.

Thermometric titration is used to determine hydrochloric acid and hydrofluoric acid (hydrogen fluoride) in etching baths containing ethanol and acetonitrile. Two endpoints appear on the titration curve that are used individually for the quantification of the respective acid.

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.

Many refiners look at discounted opportunity crudes as a means to improve their margin spread. The varieties of these cheap crude oils on the market are growing in number, but they have hidden risks for the purchaser caused by factors such as high naphthenic acid and sulfur content. Sulfur compounds and naphthenic acids are among the substances that contribute to the corrosive nature of crude oils and petroleum products. This is why the risk of corrosion is increased when processing crude oils with high naphthenic acid and sulfur content. The refiner must balance the cost benefit versus the risk and the cost of corrosion control when processing these crudes. A reliable acid number determination is a crucial part of corrosion control. Guest authors Bert Thakkar, Bryce McGarvey, and Colette McGarvey of Imperial Oil and Larry Tucker and Lori Carey of Metrohm USA were involved in the development of the new ASTM Method D8045 for acid number determination. Here, they report on the method and how it came to be.

This Bulletin describes potentiometric titration methods for the determination of the acidity in milk and yoghurt according to DIN 10316, ISO/TS 11869, IDF/RM 150, ISO 6091 and IDF 86, the chloride content in milk, butter and cheese according to EN ISO 5943, IDF 88, ISO 15648, IDF 179, ISO 21422, and IDF 242. Additionally the determination of the sodium content in milk using the thermometric titration is described. The determination of the oxidation stability of butter in accordance to AOCS Cd 12b-92, ISO 6886 and GB/T 21121 as well as the determination of lactose in lactose free milk by ion chromatography is also described.For the determination of the pH value in dairy products see Application Bulletin AB-086 and for the determination of calcium and magnesium see Application Bulletin AB-235.

Potassium is a primary macronutrient for plants, as it plays an important role in water regulation as well as plant growth. In NPK fertilizers, potassium is present besides nitrogen and phosphorus, which are the other two primary macronutrients. Knowing the quality and content of a NPK fertilizer allows an optimal fertilizer management for a planned culture, saving costs and increasing profitability.Traditionally potassium is determined gravimetrically or by flame photometry. In this Application Note, an alternative method is presented, where potassium is determined a precipitation titration. Various solid and liquid NPK fertilizers with potassium contents between 10 and 27% were analyzed. After the removal of any present ammonia, the potassium can be determined reliably in about 5 minutes.

Following the addition of caustic soda, hexafluorosilic acid can be determined through back titration of excess hydroxide with hydrochloric acid. Hydrofluoric acid (hydrogen fluoride) is determined by precipitation with aluminum in the presence of sodium and potassium ions. Nitric acid is determined by subtracting the equivalence concentrations of hexafluorosilic acid and hydrofluoric acid from the total acid concentration.

The analysis described in this poster dicusses thermometric titration as a promising method for the straightforward sodium determination in foodstuffs. Thermometric sodium titration was tested for its applicability to various food matrices such as soups, gravy and several salty snacks. Enthalpy change can be monitored as a change in temperature of the solution using a sensitive digital thermometer. The sodium determination described here relies on the exothermic precipitation of elpasolite (NaK2AlF6). The titrant is a standard aluminum solution which contains an excess of potassium ions. The titration is performed directly on a suspension of the food sample and is completed in under two minutes. The method is robust, can be fully automated and due to the highly reproducible high-frequency homogenization, copes with a variety of challenging food matrices (ketchup, instant soups, pretzels, etc.). In addition to this application note, you can find more information on thermometric sodium determination in foods in our application video available on YouTube: https://youtu.be/lnCp9jBxoEs

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 describes the determination of total sodium content in canned fish products using thermometric titration. In addition to this application note, you can find more information on thermometric sodium determination in foods in our application video available on YouTube:https://youtu.be/lnCp9jBxoEs

This bulletin discusses automated determination of sodium in milk products available to the public using a 859 Titrotherm and a 814 USB Sample Processor. The sodium content of milk can be rapidly and easily titrated thermometrically with a standard solution of Al3+ as titrant. Thermometric titrations are conducted under conditions of constant titrant addition rate. The molarity of the titrant is computed automatically in tiamoTM (software) with the SLO command. Results are reported as mg Na/100 mL. In addition to this application bulletin, you can find more information on thermometric sodium determination in foods in our application video available on YouTube:https://youtu.be/lnCp9jBxoEs

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.

Sodium can be determined thermometrically in cheese without sample preparation and addition of additives. A homogenizer is responsible for distribution and stirring. In addition to this application note, you can find more information on thermometric sodium determination in foods in our application video available on YouTube:https://youtu.be/lnCp9jBxoEs

Iron sucrose injections are used during the treatment of iron deficiency anemia. They contain a mixture of ferric iron (Fe3+) and ferrous iron (Fe2+). Ferrous iron content may be determined by subtracting the ferric iron content from the total determined iron content. Yet, this increases the measurement error due to error propagation. Alternative determination of iron(II) with cerium(IV) by potentiometric titration may be hampered, as the equivalence point cannot be determined unequivocally. Determination by thermometric titration is a more robust and therefore more reliable alternative, as this method is unaffected by the sample matrix. Here, the endpoint of the titration is indicated by a fast responding thermometric sensor. Endpoint detection is further improved by spiking the sample with 0.2% ammonium iron(II) sulfate (FAS), increasing the reliability of the determination. Compared to potentiometric titration, thermometric titration is faster and more convenient as no sensor maintenance is required. One determination takes about 2–3 minutes.

Automated mixing of a suspension and a solvent in a 50 mL dosing unit can be used to add a well-defined amount of a suspension-solvent mixture to a sample solution without clogging the dosing unit and tubing by the undiluted suspension.The method is explained by means of the TAN determination of a petroleum sample using thermometric titration. For a better endpoint recognition, small amounts of a paraformaldehyde-solvent suspension are added (catalyzed endpoint thermometric titration).

Thermometric titration can determine the total acid number (TAN) of various crude oil products according to ASTM D8045 without requiring any sensor maintenance.

Standardization of ~1mol/L tetrasodium EDTA solutions for thermometric complexometric analysis.

In an acidic solution (containing NH4F * HF, Al(NO3)3 / KNO3) sodium forms NaK2AlF6 which precipitates in an exothermic solution, enabling analysis by thermometric titration. Several foods were analyzed, namely bouillon, gravy, tomato ketchup, corn chips, pretzel sticks as well as crackers. The reproducibility of the results was good. After weighing in and adding solutions, samples were crushed with a polytron to ensure homogeneity in the measuring solution. Relative standard deviations were between 0.08% and 3.75%. In addition to this application bulletin, you can find more information on thermometric sodium determination in foods in our application video available on YouTube:https://youtu.be/lnCp9jBxoEs

Standardization of disodium dimethylglyoximate by thermometric titration with standard Ni(II) solution.

Determination of bicarbonate and carbonate in a mixture by sequential thermometric titrations.

Determination of low levels of sulfate (to approximately 20mg/L SO42-) by thermometric titration.

Standardization of 0.1mol/L perchloric acid in glacial acetic acid by catalyzed endpoint thermometric titration.

Determination of low levels of chloride (to approximately 5 mg/L Cl-) by thermometric titration.

Dissolution of oil in toluene, and titration with standard 0.1 mol/L trifluoromethanesulfonic acid in acetic acid using isobutyl vinyl ether as a thermometric endpoint indicator.

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

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

This Application Note outlines the determination of total acidic active surface sites in zeolites with thermometric titration.

Standardization of 0.1 mol/L ammonium ferrous sulfate solution for use in thermometric titration of Cr(VI) solutions.

This Application Note shows that the parameter of surface basicity of zeolites can be measured by thermometric titration.

This Application Note discusses the standardization of thiosulfate titrant for use in the determination of copper with thermometric titration.

Thermometric titration is presented as a simple, fast, and reliable method to determine calcium content in various drilling fluids.

Thermometric titration quickly and accurately assesses the total solids content of fluids employed in drilling oil and gas wells within minutes.