Several Problems Affecting the Flow Rate of SPE Cartridges
The basic operation of SPE cartridges includes five steps: activation, balance, sampling, washing, and elution. Generally speaking, those matters affecting the velocity of the SPE cartridges arise in these steps. Here we especially talk about the process of activation and balance. In that process, people fill out the fillers first. In general, reversed-phase or ion-exchange columns are activated and balanced by methanol and water respectively, while normal-phase columns are activated by petroleum ether or n-hexane.
First, filling too tight results in a slow flow rate. People can solve these matters by increasing the flow rate under pressure or purchasing products from manufacturers with strict quality control of the convection rate.
Second, when the size of the fillers is smaller, the flow rate will be slower. People need to select the proper size of columns according to the type of sample matrix and the usage habit.
The third is the difference in the pipe volume. Obviously, the large diameter and the low height of the fillers mean a fast flow rate. The selection of the columns with suitable pipe volume is also based on the type of sample matrix and the usage habit.
There are many types of SPE cartridges. In the specific experimental work, it is necessary to select suitable packing and reasonable specifications of solid-phase extraction cartridges according to the analysis object, detection methods, and laboratory conditions. We should consider the extraction ability of the solid-phase extraction cartridge for the analysis object, the volume of the sample solution, the final volume of the solution after elution, and the total amount of the analyte and the interferent in the sample solution.
Matters need attention
SPE Cartridge provided by Hawach Scientific is of high retention rate, uniform flow rate, and excellent stability. For better operation and application, there are some tips for attention. The recovery rate of the samples would be affected by inappropriate column activation conditions, too fast or too slow flow rate, improper action force of the sample solvent on the target compound, improper selection of cleaning solvent, and improper sample loaded rate. Besides, the target compounds cannot be eluted from the SPE Cartridge will be caused by too strong selectivity of fixed relative target components.
HAWACH SPE cartridges
Over the years, through the efforts of scientific and technological workers, Hawach has a wide range of products including organic element analysis, sample preparation, electrochemistry, physical optics, gas phase ion mobility spectrometry, spectroscopy, and chromatography. There are different specifications of SPE cartridges to meet various demanding experimental requirements. Moreover, they can be customized based on your specific requirements.
Several Problems Affecting the Flow Rate of the Hawach SPE Cartridges
When you use Reversed Phase C18 SPE Cartridge, Normal Phase PR Grade Florisil SPE Cartridges, and other SPE cartridge, there are several problems affecting the flow rate.
The first is the incorrect order of putting solvents. For example, if we take the water as an activating solvent for the reversed-phase column, the flow rate will be very slow. The reason for the phenomenon is that water has poor wettability to hydrophobic reversed-phase filler. Water is not as activated as methanol. Be careful when adding the solvents.
The second is insoluble activation and equilibrium solvents. When you try to use dichloromethane to activate and water to balance, you will see that the flow rate will slow down after adding water. This is due to the poor mutual solubility between water and dichloromethane, which can be solved by adding the transition solvent methanol. Methanol can be soluble in dichloromethane or water.
The third is the air in the fillers. The SPE cartridge is composed of a sieve plate, filler, and column tube. It is not organic. Therefore, there will be a slight loosening in the process of transportation, especially long-distance transportation, which leads to air entering the filler. And it is generally not easy to be found by the naked eye. It is easy to understand why there will be a slightly uneven flow rate of the same batch of columns. Dealing with this, you can use the SPE device to extract air by adding plus positive pressure, and then add the solvent together.
