Which Chemical Testing Agency to Choose {Nanjing Aikon Quanxin} Purity Testing/Elemental Analysis Short Cycle

Nanjing Aikon Analysis and Testing Center is located in the Chemical Industry Park of Jiangbei New District, Nanjing. It was established by Jiangsu Aikon Biomedical R&D Co., Ltd. and serves as a window to provide analytical testing technical services to the public. Since its establishment, the testing center has continuously developed and improved, adhering to industry-standard analytical testing laboratories and the operational philosophy of "impartial behavior, scientific methods, accurate data, and efficient service" to provide professional and efficient technical services to all sectors of society.

Our testing center currently possesses domestically advanced high-resolution 400M automated nuclear magnetic resonance spectrometers, Agilent LC-MS, GC-MS, high-performance liquid chromatography, gas chromatography, and a series of other large analytical instruments. Here, we have a high-quality management team and an experienced technical team, all oriented toward meeting customer needs, continuously updating industry standards and technical means to provide effective solutions and consistent service to our clients.

7 Common Misuses of Liquid Chromatography Columns: How Many Have You Fallen For?

1. Avoid sudden changes in pressure and temperature. Sudden temperature changes or dropping the column from a height can affect the packing inside the column; sudden increases or decreases in pressure can also disturb the column packing. Therefore, flow rate adjustments should be made gradually to maintain the stability of the column packing. 2. Avoid directly changing solvent composition. When changing the composition of the sample solution, the solvent composition should be changed gradually, especially in reverse-phase chromatography. Do not switch directly from an organic solvent to pure water, or vice versa. Moreover, when using a strong eluent to flush the column, the replacement of the mobile phase in the system should be transitioned gradually with miscible solvents. The volume of each mobile phase should be about 20 times the column volume, i.e., 50–75 mL for routine analysis.

3. Avoid backflushing the column. Generally, chromatography columns should not be backflushed. Only if the column’s instruction manual indicates that it can be backflushed should this be done to remove impurities retained at the column inlet. Otherwise, backflushing will rapidly reduce column efficiency.

4. Avoid using inappropriate mobile phases that damage the stationary phase. Select a suitable mobile phase (especially regarding pH) to prevent damage to the stationary phase. Sometimes, a pre-column can be connected before the injector. When the analytical column is a bonded silica column, the pre-column should be silica, which allows the mobile phase to be "saturated" with silica before entering the analytical column, preventing dissolution of the silica matrix in the analytical column.

5. Do not inject untreated samples directly into the column. Avoid injecting samples with complex matrices, especially biological samples, directly into the column. Sample pretreatment is necessary, or a guard column should be connected between the injector and the analytical column. A guard column is typically a short column packed with a similar stationary phase. Guard columns can and should be replaced frequently.

6. Do not store buffer solutions in the column for extended periods. When storing the column, fill it with acetonitrile or methanol, and tighten the column fittings to prevent solvent evaporation and drying. Do not leave buffer solutions in the column standing overnight or longer.

7. Do not seal the column without proper treatment. After use, the column must be cleaned with an appropriate solvent. For example, an ODS column should be flushed with methanol until baseline equilibrium is achieved; when using salt buffer solutions as the mobile phase, flush with a salt-free mobile phase after use; compounds containing halogen elements (fluorine, chlorine, bromine) may corrode stainless steel tubing and should not be in prolonged contact; if the column installed on the HPLC is not used frequently, it should be flushed for 15 minutes every 4–5 days.

Article source: Analysis and GMP Reprinted platform: Analysis and GMP Responsible editor: Hu Jing