High pressure liquid chromatography curves

Measurements of the common physical constants such as boiling point or refractive index are not sufficiently sensitive to determine the trace amounts of impurities in question. Besides the common spectroscopic methods, techniques like gas chromatography (GC), high-pressure liquid chromatography (HPLC), or thin-layer chromatography (TLC) are useful. The surest criterion for the absence of interfering foreign compounds lies in the polymerization itself the purification is repeated until test polymerizations on the course of the reaction under standard conditions are reproducible (conversion-time curve, viscosity number of the polymers). 

Benzoic acids (BAs), and their respective sodium, potassium, and calcium salts are the most commonly used preservatives in foodstuffs. Most often high-pressure liquid chromatography (HPLC) methods [71] are used for the determination of benzoates in food and beverage products. Several attempts have been made [72, 73] for developing the benzoate-selective electrode as a sensor applicable in a simple cost-effective measuring procedure. Alizadeh et al. [74] developed a solid contact electrode on a platinum-based sensing element. For the preparation of the selective benzoate measuring film, pyrrole was electropolymerized in the presence of sodium benzoate and sodium dodecyl benzenesulfonate. The slope of the calibration curve of the electrode was 55.4mV/decade in the benzoate concentration... 

A procedure for the rapid separation of berkelium from other actinides, lanthanides, and fission products was developed in order to measure the decay properties of short-lived isotopes [54]. Bk and Ce were separated from other elements using solvent extraction with HDEHP followed by cation-exchange high-pressure liquid chromatography (HPLC) using a-hydroxyisobutyrate as the eluant. The elution curve, showing a clean separation of Bk from Ce, is shown in... 

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