Applications

Several testing methods such as the determination of the acid and the iodine numbers in biodiesel as well as the quantification of sulfate and chloride in bioethanol are described.

A complete tap water analysis includes the determination of the pH value, the alkalinity and the total water hardness. Both the pH measurement and the pH titration by means of a standard pH electrode suffer from several drawbacks. First, the response time of several minutes is too long and, above all, the stirring rate significantly influences the measured pH value. Unlike these standard pH electrodes, the Aquatrode Plus with its special glass membrane guarantees rapid, correct and very precise pH measurements and pH titrations in solutions that have a low ionic strength or are weakly buffered. Total water hardness is ideally determined by a calcium ion-selective electrode (Ca ISE). In a complexometric titration, calcium and magnesium can be simultaneously determined up to a calcium/magnesium ratio of 10:1. Detection limits for both ions are in the range of 0.01 mmol/L.

Commercially available fuels are complex mixtures of hundreds of different hydrocarbons. For the calibration of the test engines or advanced experimental and computational research they are modeled by means of multicomponent surrogate mixtures that adequately represent the desired physical and chemical characteristics. By definition, every octane and cetane number corresponds to a specific mixing ratio of primary reference fuels (PRFs). Based on this information, the tiamoTM controlled automatic dosing device prepares the surrogate mixtures. The setup drastically minimizes time-consuming and error-prone manual preparation steps and the contact with hazardous solvents. Additionally, precise and accurate results are displayed on customizable reports that fully comply with all current GLP and GMP requirements.

Compared to the classical Epton titration, potentiometrically indicated two-phase titrations using organic-solvent-resistant Surfactrodes can be easily automated and require no toxic and environmentally hazardous chloroform. Even challenging matrices such as fats and oils in bath oils and hair conditioners or strong oxidizing agents in washing powder and industrial cleaners do not interfere with the titration of the ionic surfactants. Results obtained show excellent agreement to those of the Epton titration. Irrespective of the matrix, relative standard deviations of threefold determinations are all below 2.1%. While the Surfactrode Resistant is mainly used for oil-containing formulations, the Surfactrode Refill is ideal for washing powders and soaps. Both electrodes excel by their ruggedness and allow the rapid and precise determination of anionic and cationic surfactants.

Benzbromaron is one of the main uricosuric drugs currently used. In addition to sophisticated and expensive LC-MS and GC-MS methods, benzbromaron can be effectively determined by titration with sodium hydroxide solution using a straightforward, fully automated sample preparation method. A high-frequency homogenizer comminutes one or three tablets within 90 or 120 s respectively. The overall analysis time is 8 minutes. Ten-fold determinations with one and three tablets resulted in a benzbromaron content of 99.2 and 98.7 mg per tablet respectively. Increasing the number of tablets from one to three lowers the RSD from 1.36 to 0.88%. These results show an excellent agreement with the benzbromaron content indicated by the manufacturer (approx. 100 mg/tablet).Besides the presented Titrando/homogenizer combination, the other two members of the 815 Robotic Soliprep Sample Processor family offer comprehensive sample preparation possibilities within the fields of IC, HPLC, ICP or voltammetry.

This poster presents a highly reproducible procedure for the determination of the sodium contribution of acid-extractable organic species in Bayer process liquor. The precision of the method is estimated to be 0.2% RSD.

Hydroxyl is an important functional group and knowledge of its content is required in many intermediate and end-use products such as polyols, resins, lacquer raw materials and fats (petroleum industry). The test method to be described determines primary and secondary hydroxyl groups. The hydroxyl number is defined as the mg of KOH equivalent to the hydroxyl content of 1 g of sample.The most frequently described method for determining the hydroxyl number is the conversion with acetic anhydride in pyridine with subsequent titration of the acetic acid released: H3C-CO-O-CO-CH3 + R-OH -> R-O-CO-CH3 + CH3COOH. However, this method suffers from the following drawbacks: - The sample must be boiled under reflux for 1 h (long reaction time and laborious, expensive sample handling) - The method cannot be automated - Small hydroxyl numbers cannot be determined exactly - Pyridine has to be used, which is both toxic and foul-smellingBoth standards, ASTM E1899-08 and DIN 53240-2, offer alternative methods that do not require manual sample preparation and therefore can be fully automated: The method suggested in ASTM E1899-08 is based on the reaction of the hydroxyl groups attached to primary and secondary carbon atoms with excess toluene-4-sulfonyl-isocyanate (TSI) to form an acidic carbamate. The latter can then be titrated in a non-aqueous medium with the strong base tetrabutyl- ammonium hydroxide (TBAOH). The method suggested in DIN 53240-2 is based on the catalyzed acetylation of the hydroxyl group. After hydrolysis of the intermediate, the remaining acetic acid is titrated in a non-aqueous medium with alcoholic KOH solution. The present work demonstrates and discusses an easy way to determine the hydroxyl number according to ASTM E1899-08 or DIN 53240-2 with a fully automated titrimetric system for a great variety of industrial oil samples.

Sodium fluoride is used as a preservative in biological samples for alcohol analysis. All submitted blood samples, including those taken from vehicle drivers suspected of driving under the influence of liquor, have to be tested for adequate preservation prior to alcohol determination by gas chromatography. This is critical to ensure adequate sample preservation. Inadequate sample preservation may allow glycolysis and/or microorganism growth to produce ethanol.In the past this has been done by direct potentiometric measurement using a fluoride-selective electrode (F ISE), an ion meter and certified NaF standards. The sodium fluoride level was determined manually by dipping the electrode directly into the blood sample. Results were recorded manually. This poster describes two independent automated methods of analysis that allow the minimization of this tedious and time-consuming procedure.In the first one, the fluoride content in a blood aliquot is measured by direct potentiometric measurement after the addition of TISAB and deionized water. The second method employs the titration of the sample aliquot with La(NO3)3 after adding a buffer solution.

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 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