Solid Phase Extraction (SPE in short) technology was developed in the 1970s. Due to its advantages such as reliability, low consumption of reagents, etc., it has replaced traditional liquid-liquid extraction in many fields and has become an effective means of sample pretreatment, which have been used more and more widely in the laboratory.
When low recovery of analyte and poor reproducibility of extraction occur, it is better to collect the sample, then carry out analysis, and determine the source of the problem. SPE cartridge can be used as a good supplement to pretreatment, but it is necessary to be aware of the advantages and disadvantages, pay attention to local conditions, strengths and circumvent weaknesses.
1. Which sample loading method is suitable for the SPE instrument? Currently, there are two methods of extraction: positive pressure loading and negative pressure loading. However, negative pressure loading can not effectively control the flow rate, which results in unstable recovery and poor repeatability of the instrument. Therefore, mainstream manufacturers generally use positive pressure loading method. The automatic solid-phase extraction instrument uses a high-precision syringe pump to positively load the sample to elute the sample, which further controls the liquid flow rate, thereby significantly improving the repeatability of the instrument and ensuring the sample recovery rate.
2. What are the requirements for the processing speed of the automatic SPE? The solid-phase extraction cycle of a single sample is generally about 20 minutes, and the solid-phase extraction instruments of general manufacturers are similar. Therefore, in general, the more samples the instrument processes simultaneously, the faster the processing speed. Full-automatic solid-phase extraction has more flexible extraction, which maximizes sample processing speed.
3. Can the SPE instrument effectively avoid the blockage of the flow path during the extraction process? Common problems encountered in the application of automatic solid-phase extraction instrument: blockage of the flow path causes the instrument to malfunction. When column clogging occurs, most solid-phase extraction instruments cannot detect automatically, causing samples and solvents to leak, causing serious losses and cross-contamination. HAWACH solid-phase extraction instrument has a built-in high-sensitivity pressure sensor in the flow path. When the pressure in the flow path is> 0.6Mpa, the system will automatically alarm to protect the device effectively.
4. Can the HAEACH SPE instrument effectively control cross-contamination? In some automatic solid-phase extraction instruments, the sample and solvent use the same pipeline, which is likely to cause pollution. Especially for instruments without cleaning function, a variety of compounds will remain in the pipeline in a short time, which is the root cause of many experimental failures. The HAWACH solid-phase extraction instrument uses a flow path separation unit to automatically select the solvent. The organic solvent waste liquid has an independent waste liquid channel, which effectively avoids cross-contamination.