assware and solvents are clean when you start. If you are going to recycle, use a very large volume of solvent like 5 liters for standard bore columns and be willing to deal with this problem. An unequilibrated mobile and stationary phase system can also produce this drift, just consider the first example of a gradient. If you are operating in an isocratic mode, wait longer until you are equilibrated. Try cleaning the column with a series of solvents and gradients before you start equilibrating. This will help in achieving a more rapid equilibration. Contamination bleed in the system can also cause this drift, especially when using a gradient. The contamination may precipitate from solution at the beginning, and then redissolve at the end of the gradient. Start w/clean.
鬼 峰 鬼峰——即使不样也会出现的峰 How many people have seen this? Peaks without a injection? We call these ghost peaks, and we usually see these in a blank gradient method. The problem is pronounced contamination in the mobile phase or the column. Once upon a time there was an environmental firm, new to HPLC, that was analyzing for PAH’s. The gradient acetonitrile/water method looked like this baseline, even without the sample being injected. When asked about the quality of the acetonitrile and water, they responded by showing their nice bottles from a reputable solvent vendor. Upon further investigation and inspection of the HPLC system, the application chemist for HP saw that their solvent reservoir marked "WATER", was in fact a Jacuzzi. Froth and foam everywhere! The moral of the story, always suspect your glassware, especially if you are using a dishwasher or dishwashing service. Residual soapy surfactants have been known to linger even after 2 to 3 rinses, producing profound contamination and possible destroying or permanently modifying the column stationary phase. Use HPLC grade. A good practice to get into with glassware, is too rinse the glass wear 2 to 3 more times with water to remove any soap film, then rinse 2 to 3 times with whatever solvent is appropriate for your system. You may have to rinse in between the water and solvent with a universal solvent such as THF, or IPA. Column contamination can be remedied by cleaning with a series of solvents and gradients, or a new column.
峰 型 可能原因： 柱中有死体积 过滤片部分堵塞 只有一个双峰——组分的共洗脱 样品与溶剂不匹配 There are many peak shape problems that can occur, this one is peak doubling. This is when the original analysis produces a certain number of peaks in a mixture, then after some time, these peaks multiply by 2, and look like the red chromatogram.
