High performance liquid chromatography technique

Despite its potential importance, formic acid has proven difficult to quantify at submicromolar levels in non-saline water samples. Formidable analytical difficulties are associated with its detection in highly saline samples. Ion exclusion, anion exchange, and reversed-phase high performance liquid chromatography techniques based on the direct detection of formic acid in aqueous samples are prone to interferences (especially from inorganic salts) that ultimately limit the sensitivity of these methods. 

The isocratic system (Fig. 1.2 (a)) provides an economic first step into high-performance liquid chromatography techniques. The system is built around a high-performance, dual-piston, pulse-free pump providing precision flow from 0.01 to 5ml min-1. 

High performance liquid chromatography techniques may be successfiilly applied to analyze phthalate esters. A 15 or 25 cm column filled with 5 or 10 pm silica-based packings is suitable. Short columns (3.3 cm x 4.6 mm), commonly called 3x3 columns, offer sufficient efficiency and reduce analysis time and solvent consumption Phthalate esters resolve rapidly on a 3 x 3 Supelcosil LC-8 column (3 pm packing) at 35°C and detected by a UV detector at 254 nm. Acetonitrile-water is used as mobile phase (flow rate 2 ml/min injection volume 1 mL). Other equivalent columns under optimized conditions may be used. 

High-performance liquid chromatography techniques have also been used in the determination of logP values. A potential problem with the use of HPLC retention data is that it is not a direct method and thus requires calibration. Purthermore, there may be problems with performing experiments above pH 8. 

Shamsul Hairi, S., Yoshihiro, S., Yoshiaki, K., and Kiyokatsu, J., Solventless sample preparation procedure for organophosphorus pesticides analysis using solid-phase microextraction and online supercritical fluid extraction/high performance liquid chromatography technique. Anal. Chim. Acta, 433, 207-215, 2001. 

High performance liquid chromatography Technique for separating chemicals in solution by passing an inert solvent over a sorbent. 

Separation of Polysaccharides Using High-Performance Liquid Chromatography Technique... 

Solid phase extraction (SPE) is a relatively new technique, which is similar in appearance and function to column chromatography and high-performance liquid chromatography (Techniques 19 and 21). In some applications, SPE is also similar to liquid-liquid extraction, discussed in this technique chapter. In addition to performing separation processes, SPE can also be used to carry out reactions in which new compounds are prepared. 

Diets rich in plant-derived foods can provide more than 1 g of phenolic compounds per day, although there are major international and interindividual differences in exposure. Flavonols, flavones, and fla-van-3-ols constitute the three major subclasses of flavonoids, and a significant amount of information on the content of selected flavonoids from these subclasses in fruits and vegetables has been obtained using high-performance liquid chromatography techniques. The other subclasses are flavanones, anthocyanidins, and isoflavones. 

Typically, quantitative protein determination is done on the one hand by colorimetric or nephelometric methods, on the other hand for more difficult analytical problems by more sophisticated techniques such as high performance liquid chromatography (HPLC), gel-electrophoresis and immunoassay. However, these methods are tedious, time-consuming and expensive. 

High performance liquid chromatography (HPLC) is an excellent technique for sample preseparation prior to GC injection since the separation efficiency is high, analysis time is short, and method development is easy. An LC-GC system could be fully automated and the selectivity characteristics of both the mobile and stationary... 

Purification of poloxamers has been extensively investigated due to their use in medical applications, the intention often being to remove potentially toxic components. Supercritical fluid fractionation and liquid fractionation have been used successfully to remove low-molecular weight impurities and antioxidants from poloxamers. Gel filtration, high-performance liquid chromatography (HPLC), and ultrafiltration through membranes are among the other techniques examined [5]. 

In this book, I have tried to show the way in which high performance liquid chromatography-mass spectrometry (LC-MS) has developed, somewhat slowly it has to be said, into a powerful hybrid analytical technique. 

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