High-performance liquid chromatography temperature

Vanheukelem, L. et al., Improved separations of phytoplankton pigment using temperature-controlled high-performance liquid chromatography. Mar. Ecol. Prog. Ser., 14, 303, 1994. 

Dapremont, O., Cox, G.B., Martin, M., Hilaireau, P., and Colin, H., Effect of radial gradient of temperature on the performance of large-diameter high-performance liquid chromatography columns I. Analytical conditions,. Chromatogr. A, 796, 81, 1998. 

Antia, F. D. and Horvath, Cs., High-performance liquid chromatography at elevated temperatures examination of conditions for the rapid separation of large molecules,. Chromatogr., 435, 1, 1988. 

Henderson, D. E. and Mello, J. A., Physicochemical studies of biologically active peptides by low-temperature reversed-phase high-performance liquid chromatography, /. Chromatogr., 499, 79, 1990. 

Vasanits, A. and Molnar-Perl, I., Temperature, eluent flow-rate and column effects on the retention and quantitation properties of phenylthiocarbamyl derivatives of amino acids in reversed-phase high-performance liquid chromatography, J. Chromatogr., A, 832,109, 1999. 

Stoll, D.R., Cohen, J.D., Carr, P.W. (2006). Fast, comprehensive online two-dimensional high performance liquid chromatography through the use of high temperature ultra-fast gradient elution reversed-phase hquid chromatography. J. Chromatogr. A 1122 (1-2), 123-137. 

In addition to GC/MS, high performance liquid chromatography (HPLC/MS) has been used to analyse natural resins in ancient samples, particularly for paint varnishes containing mastic and dammar resins [34]. A partial limitation of chromatographic techniques is that they do not permit the analysis of the polymeric fraction or insoluble fraction that may be present in the native resins or formed in the course of ageing. Techniques based on the direct introduction of the sample in the mass spectrometer such as direct temperature resolved mass spectrometry (DTMS), direct exposure mass spectrometry (DE-MS) and direct inlet mass spectrometry (DI-MS), and on analytical pyrolysis (Py-GC/MS), have been employed as complementary techniques to obtain preliminary information on the... 

As a consequence of the previous considerations Kieber et al. [75] have developed an enzymic method to quantify formic acid in non-saline water samples at sub-micromolar concentrations. The method is based on the oxidation of formate by formate dehydrogenase with corresponding reduction of /3-nicotinamide adenine dinucleotide (j6-NAD+) to reduced -NAD+(/3-NADH) jS-NADH is quantified by reversed-phase high performance liquid chromatography with fluorimetric detection. An important feature of this method is that the enzymic reaction occurs directly in aqueous media, even seawater, and does not require sample pre-treatment other than simple filtration. The reaction proceeds at room temperature at a slightly alkaline pH (7.5-8.5), and is specific for formate with a detection limit of 0.5 im (SIN = 4) for a 200 xl injection. The precision of the method was 4.6% relative standard deviation (n = 6) for a 0.6 xM standard addition of formate to Sargasso seawater. Average re-... 

These experiments were carried out mainly by NMR spectrometry ( H and ljC) and high performance liquid chromatography. Stopped-flow and low temperature techniques were used in some of the NMR experiments. In all cases the reactions were aimed at monitoring the half-life of the starting materials as well as monitoring the products which were formed. Detailed procedures will appear shortly [15]. 

As a consequence of this there has, in recent years, been a growing interest in applying high-performance liquid chromatography which is not subject to this temperature limitation, to the determination of the non-volatile fractions of water. 

High Performance Liquid Chromatography (HPLC) (Chapter 30) gives an elaborate discussion of theoretical aspects. Instrumentation encompasses the various important components e.g., solvent reservoir and degassing system pressure, flow and temperature pumps and sample injection system ... 

Lou, D.-W., Saito, Y., Zarzycki, P. K., Ogawa, M., and Jrrmo, K. (2006b). Isocratic separation of ginsenosides by high-performance liquid chromatography on a diol column at subambient temperatures. Ancd. Bioanal. Chem. 385, 96-104. 

Nitrobenzene oxidation was carried out by adding 50 mg of dry soda lignin into a mixture of 7 mL of 2 M NaOH and 4 ttiL of nitrobenzene in a 15 ttiL steel autoclave. Then, the antoclave was heated to 165°C for 3 hours in a preheated thermostat oil bath. After the autoclave was cooled to room temperature, the mixture was then transferred to a liqnid-hquid extractor for continuous extraction with chloroform (5 x 20 mL) in order to remove any nitrobenzene reduction product and excess nitrobenzene. The oxidation mixtnre was then acidified by concentrated HCl to pH 3 and further extracted with chloroform (5x15 mL). The solvent from the second chloroform solution was then removed using a rotary evaporator at 40°C under reduced pressure in order to obtain the nitrobenzene oxidation mixture. The mixture was then dissolved into dicloromethane and made up to 10 luL. This mixture was then used as a stock solution for high performance liquid chromatography (HPLC) analysis [6]. 

Assay of the reaction mixture. The samples were then resuspended in 1.5 mL isopropanol and assayed to determine both the yield and ee by chiral normal phase high-performance liquid chromatography (HPLC). A 250 mm x 4.6 mm Chiralpak AD-H column was used with an eluant of 95 5 heptane/ethanol, a flow rate of 3 mL min a temperature of 10 °C and a detection wavelength of 210 nm. 

---