藥物分析新方法與新技術(shù)-液相色譜聯(lián)用技術(shù)及其應(yīng)用-張尊建-文庫吧資料
2025-01-12 08:39本頁面
【正文】 w ? In this mode, the eluent is directly flowing from the chromatographic system into the NMR probe. As only selected peaks are measured in the NMR spectrometer. The separation is monitored in parallel with an LC detector (typically a UV detector). ? The peak is selected from the chromatogram recorded by the LC detector. The separation is interrupted after a certain time delay which is necessary to allow the peak to ‘move’ from the LC detector to the NMR detection cell. ? The sample remain static in the flow cell and the condition will remain stable during the whole NMR experiment. The parameters can be precisely adapted for the measurement of each individual sample. ? Advantage: Good NMR signal, LC2D NMR. ? Disadvantage: timeconsuming and peak broadening. a precise TD value has to be tested. memory effect. 26 LCNMR under static conditions － Loop storage/loop transfer ? In this case, the eluent is directly flowing from the chromatographic system into a storage device. As only selected peaks are measured in the NMR system. The separation is monitored in parallel with an LC detector (typically a UV detector). ? The peak is selected from the chromatogram recorded by the LC detector, and the storage loop is isolated after a certain time delay which is necessary to allow the peak to ‘move’ from the LC detector into the loop. ? At a later stage, after the separation is finished, the loop contents are transferred in arbitrary order into the NMR spectrometer. Now, all kinds of 1D and 2D NMR measurements can be carried out. 27 LCSPENMR （ Combined use of HPLCMS and HPLCNMR together with solidphase extraction） ? Be utilized to solve the problem of low concentration, such as：trace analysis.
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