The Selection of SPE Cartridge
To select the appropriate SPE cartridge, we normally consider it from two aspects: the selection of adsorbent and specification of the cartridge. The use of appropriate adsorbent can achieve good separation between interfering substance and target component, and also meet the requirement of recovery. However, the mass of chemical compound which can be adsorbed by the adsorbent is limited, once the mass of the sample is too large, there can be overload which happens in the SPE cartridge, and therefore makes the target component directly go through the cartridge without being reserved.
Basically, we can select the adsorbent according to the properties of the target component and the substance. Moreover, for the concrete examples, we can also select the adsorbent which is based on the principle of “distinguish the target component and the main interferent”.
After selecting the appropriate adsorbent, we need to select the corresponding specification of the cartridge according to the volume of sample which needs to be determined. Because the mass of chemical compound which can be adsorbed by the adsorbent in SPE cartridge is limited, once the value exceeds it, the target component will not be reserved effectively. As a result, it is necessary to select the appropriate specification of SPE cartridge.
About the frequently asked question when using SPE cartridge, normally there are low recovery rate, poor reproducibility, bad purifying effect, and excessively fast or slow flow rate.
For the low recovery rate, we can use blank solvent and then recycle the loading solution and eluent. If the actual detect concentration exceeds 5% of the content, it means the target component is not well reserved on the filler. The possible causes are a lot. For example, the selection of the SPE cartridge is not appropriate, then we should choose the cartridge with stronger reservation capacity. Also, the loading solution or the eluent of the sample may have excessively strong eluting power, all we need to do is to decrease the power.
Furthermore, if we also use blank solvent and recycle the loading solution and eluent, then we do not detect the target component. Meanwhile, we also get a low recovery rate when recycling the eluent. It means the target component is not completely eluted. In general, there are three possible causes. One is that the SPE cartridge has excessively strong reservation capacity. Another one is that the elution power is too strong. And the last one is that the elution volume is too small. To resolve the problems, we can choose the SPE cartridge with relatively weak reservation capacity, improve the elution power, and increase the elution volume respectively.
SPE Cartridge offered by Hawach Scientific has some remarkable characteristics, such as average pore size, great flow rate, the big range of PH and great chemical compatibility. Its unique modified surface structure is water-wettable to promote robust, reliable sample preparation; its media exhibits both reversed phase and ion exchange retention for a wide range of basic and neutral compounds which is stable over the complete PH range and suitable for a wide range of mobile phases. It also provides a unique alternation to packed column technology, which brings benefits in defining and controlling critical surface chemistry parameter and ensure performance consistency.
