(1) Mobile phase: must be used after chromatography through the filter after use, and the mobile phase ratio can not be completely in accordance with the standard.
(2) Abnormal column pressure: the bubble inside the column, with the syringe to the bubble out, the column pressure back to normal. Column height: internal obstruction problems occur.
(3) Accuracy of external standard method: the accuracy of the external standard method related to the determination of the results, so the injection must be accurate results, the standard peak area RSD value should be less than 2.0. The general injector should not have bubbles present when extracting samples.
(4) When the test sample or standard peak pinning phenomenon, should check whether the phenomenon of collapse of the column occurred, if any, then re-column or change the new pillars.