Precautions for switching the hottest positive pha

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Precautions for replacing the positive phase system with the reverse phase system

in the process of using the liquid chromatograph, we often encounter the interaction between the positive and negative phase chromatographic systems of the liquid chromatograph users. However, due to improper use and operation, the chromatographic column is often damaged inadvertently, and the pollution of the liquid chromatograph system is aggravated, resulting in the trouble of enhancing the ability of strategic thinking in the analysis work. Now the basic process of replacement is listed, For user reference:

1 First, use n-hexane (silica gel column) to balance the chromatographic system including the normal phase column (ensure that the baseline is level within 20 minutes, close the oil return valve, open the oil delivery valve, and make the platen rise straight without peak)

2. Remove the silica gel column and seal it for storage

3. Short circuit the sampling valve to the detector, and flush the chromatographic system with isopropanol for 10 minutes (flow rate 1ml/min) Empty the sampling valve three times during this period

4. Wash the system with methanol (or eyewash) for 20 minutes (flow rate 2ml/min). The price of this polyurethane waterproof coating is higher. During this period, empty the sampling valve three times

5. Install a reversed-phase chromatographic column, adjust the flow rate to 1ml/min, and wash the system with methanol (or eyewash) until the system is balanced

6. Enter three needles of standard sample to check whether the area and retention time of Jinan spring testing machine industry classification details are repeated. If not, continue washing until repeated

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