When performing precipitation in a centrifuge tube, use […]
When performing precipitation in a centrifuge tube, use a dropper to draw the reagent dropwise into the centrifuge test tube containing the test solution of the ion to be detected. Each drop of reagent should be fully shaken.
In order to check whether the precipitation is complete, centrifuge the centrifuge tube with the reagent added, and then drop the reagent along the tube wall, carefully observe whether there is turbidity in the supernatant, if there is no turbidity, it means the precipitation is complete.
Otherwise, the reagents must be added dropwise and centrifuged again until the precipitation is complete.
After centrifugal sedimentation, the lower end of the centrifuge tube is the sediment, and the upper part is the solution. At this time, a capillary pipette can be used to suck the supernatant into another centrifuge tube to separate the precipitate and the solution. Note that when using a capillary pipette to suck the solution, you must pinch the rubber nipple before inserting the solution. Do not pinch the rubber nipple after inserting the solution, because this will mix the clear liquid. After the capillary pipette is inserted into the solution, the rubber nipple should be relaxed slowly so that the solution is slowly sucked into the tube.
If necessary, repeat several times to separate the precipitate from the solution.
The pellet can also be washed in the centrifuge tube. Add a proper amount of deionized water or a suitable electrolyte solution to the centrifuge tube with the sediment, stir it with a stir bar, and then centrifuge.
When washing, use a washing solution equal to 2 to 3 times the precipitation volume each time, usually 1 to 3 times. Before each wash, remove the solution as much as possible. When washing, try to tilt the centrifuge tube and move it fully so that the precipitated particles come into contact with a large amount of washing liquid.