Minimizing ultraviolet noise due to mis-matches between detector flow cell and post column mobile phase temperatures in supercritical fluid chromatography: effect of flow cell design.

摘要: Abstract A mis-match between the post-column mobile phase temperature and UV detector flow cell can cause significant noise in supercritical fluid chromatography (SFC). Deviations as little 5 °C increase much 5 times, making unsuited for trace analysis. Two approaches were used to minimize this noise. When a was direct thermal contact (metal on metal) with optical bench, actively controlled measured temperature, by using one of heat exchangers (HX) column compartment. However, some older, but still widely designs, required repeated, hourly monitoring repeated manual adjustment exchanger due drift. Flow design had strong influence susceptibility thermally induced Thermally insulating from bench made cells less susceptible such Five different cells, insulated, un-insulated, evaluated. Most truncated conical path, cylindrical path. Using either approach, ASTM noise, 10 mm, 13 μL cell, could be optimized ≈0.007 mAU at 2.5 Hz, SFC, which is very near 0.006 mAU manufacturer's specification HPLC. The insulated version far optimization, compared un-insulated version. At 150 bar, an experimental 3 mm, 2 μL only side yielded slightly too high (≈0.16–0.18 mAU) analysis, 80 Hz. 200 bar, 80 Hz 10. Even partially Further failed improve performance.