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- Posts: 42
- Joined: Wed Sep 14, 2011 1:47 pm
Mobile phase: 0.005M Nitric acid (HPLC grade) diluted with de-ionized water (conductivity less than 0.1 µS). It is filtered through 0.45µm membrane and sonicated for 30 minutes to eliminate all remained bubble.
Column oven: 40 C (there is another component that needs temperature to be kept at 43 C but I do not know what to call it, sorry for my bad English)
Flow rate: 1.0 mL/minute.
My sample are prepared by diluting high-purity Potassium Chloride and Sodium Chloride in the same de-ionized water used for mobile phase preparation.
Here is my problems.
1. Peak due to Sodium is fronting (Asymmetry factor: 0.755), whereas, peak due to Potassium is tailing (Tailing factor: 1.749) although I am using a totally newly-purchased column (Shimadu column IC - C1) which is certified to have great performance with alkaline analysis using test conditions same to mine.
2. Retention time fluctuates day after day although I used the same mobile phase.
Any advice would be highly appreciated. Thanks in advance.