High-performance liquid chromatography column ovens

To control and maintain the critical temperature of the mobile phase (CO2), the column is installed in an oven, similar to those used for GC or high-performance liquid chromatography (HPLC), depending on the type of column used (Fig. 2). 

Chemical Analysis. Gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) techniques were used to analyze 4-chlorophenol and its oxidation intermediates. For GC-MS analysis, the samples were acetylated in pyridine. The samples were first evaporated to dryness. Then 200 xL of pyridine and 200 (xL of acetic anhydride were added to the dry residue. The samples were heated at 65 °C for 2-3 h to ensure the complete acetylation reaction, and then gently evaporated to dryness in a nitrogen stream. Finally, the residue was redissolved in 0.1 mL of hexane for GC analysis. A GC (HP model 5890) equipped with mass selective detector (HP model 5971) and SPB-5 capillary column (Supelco Co., PA., 25- X 0.2-mm i.d. X 0.33-p.m film thickness) was used. To separate different intermediate products, various oven-temperature programs were performed. The GC-MS interface line was maintained at 300 °C. The mass-... 

Total Hg determined by CVAAS after pressurized digestion with H2SO4/HNO, in microwave oven, and reduction with SnCU. For MeHg, 250 mg pre-treated by addition of H2S04/NaCl, water steam distillation, addition of acetate buffer, and complexation with sodium pyrrolidine dithiocarbamate, separation by high performance liquid chromatography after preconcentration on a CIS column, followed CVAAS detection (Lab.05)... 

Procedure (See Chromatography, Appendix BA.) Use a suitable high-performance liquid chromatograph equipped with differential refractometer, autosampler injection unit, mobile-phase degasser, column heating block or oven, and a computing integrator. The column is Lichrosorb RP-18 250-mm x 4.5 mm (id) (GL Science, Inc., or equivalent) and YMC-Pack ODA-A A-303 250-mm x 4.5 mm (id) (YMC Company, Ltd., or equivalent) connected in a series, or equivalent, maintained at 50°. Use 80 20 acetone acetonitrile as the eluent, at a flow rate of 2 mL/min. 

SEC was performed according to the method of Chin et al. (1994). A Shodex KW802.5 SEC column (Waters Corp., Milford, MA., USA) was used and a Waters liquid chromatography system consisting of the following components was used for the analysis Waters 501 high pressure pump. Waters 717 autosampler, InterAction column temperature control oven, Waters 484 UV/VIS detector, and Waters Millenium 2.0 computer software package. 

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