Solutions to common problems in solid phase extraction


Shanghai Haozhuang Instrument Co., Ltd. has developed the LNB brand solid phase extraction device, which is energy-saving and environmentally friendly, leading the country. The solid phase extraction device uses a solid adsorbent to adsorb the target compound in the liquid sample, separate it from the sample matrix and interfering compounds, and then elute with the eluent or heat to desorb to achieve the purpose of separating and enriching the target compound ( That is, the separation, purification and enrichment of samples), the purpose is to reduce sample matrix interference and improve detection sensitivity, which is used in various food safety tests, agricultural product residue monitoring, medicine and health, environmental protection, commodity inspection, tap water and chemical production laboratories .

The following are common questions about solid phase extraction equipment:
1. Which sampling method is best for the solid phase extraction instrument?
Currently, two methods of positive pressure and negative pressure sampling are commonly used in the market, but negative pressure sampling causes unstable recovery rate and poor instrument repeatability due to the inability to effectively control the flow rate, so mainstream manufacturers generally use positive pressure sampling In this way, the automatic solid phase extraction instrument uses a high-precision syringe pump to positively load the sample to elute the sample, which controls the liquid flow rate more accurately, thereby significantly improving the repeatability of the instrument and ensuring sample recovery.
2. What are the requirements for the sample processing speed of automatic solid phase extraction?
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. Fully automatic solid phase extraction uses 6 channels + 3 modes for flexible extraction, which maximizes the sample processing speed.
3. Can the automatic solid phase extraction instrument effectively avoid the blockage of the flow path during the extraction process?
Common problems encountered in the application of automatic solid phase extraction equipment: blockage of the flow path causes instrument failure.
When column clogging occurs, most solid phase extraction instruments cannot be automatically detected, causing samples and solvents to leak, causing serious losses and cross-contamination. The flow path of the automatic solid phase extraction instrument is equipped with a highly sensitive pressure sensor. When the flow path pressure is greater than 0.6Mpa, the system will automatically alarm to effectively protect the device.
4. Can the automatic solid phase extraction instrument effectively control cross contamination?
In some automatic solid phase extraction instruments, the sample and solvent use the same pipeline, which is easy to cause pollution. Especially for instruments with no cleaning function, many compounds will remain in the pipeline in a short time, which is the root cause of many experimental failures. . The automatic solid phase extraction instrument adopts a flow path separation unit to automatically select the solvent, and the organic solvent waste liquid has an independent waste liquid channel, which effectively avoids cross contamination.
5. How should users choose the appropriate solid phase extraction method?
The easiest way to establish a solid phase extraction method is to search from published standard literature or information provided by SPE column manufacturers. But because the sample matrix may be different, even the target compound is different, the method provided in the literature is not necessarily the most optimized method. Therefore, the extraction parameters in these methods need to be optimized.
There are three steps to establish a solid phase extraction method:
(a) Assemble relevant information;
(b) Establish a preliminary solid phase extraction method;
(c) Optimize the parameters in the method;
The AutoSPE control software of the automatic solid phase extraction instrument is a user-friendly and graphical Chinese operation software. From the system configuration and method establishment to the establishment of special instructions, the user's needs are fully considered. The solid-phase extraction instructions included in the software include activation, sample loading, rinsing, drying, and elution, as well as the common liquid handling instructions in the laboratory, which makes the establishment and optimization of the method more convenient.
6. Common problems in solid phase extraction:
(1) Flow rate: Vacuum, pressure, gravity and other factors will affect the flow rate of liquid through the SPE column. Stable flow rate is very important for extraction efficiency, especially the sample passing through the column and the elution step. Too fast a flow rate will reduce the recovery rate of target compounds, especially solid phase extraction based on ion exchange. Too slow a flow rate will extend the analysis time and reduce work efficiency.
Six high-precision ceramic metering pumps are used to load samples at positive pressure, which ensures accurate delivery of liquid at the specified flow rate at a stable flow rate, ensuring high accuracy and repeatability of the analysis results.
(2) Recovery rate problem: Generally speaking, when the extraction recovery rate result is not ideal, it should be carefully and systematically eliminated item by item, find out the cause, and then improve the extraction method. To establish a stable and reliable method, the flow rate can directly affect the final result, so it is very important to control the flow rate.
(3) Pollution problem: The pollution generated by the column depends largely on the concentration of the target compound and the detection method used. Manufacturers with quality control can usually control pollutants in the order of PPb, and pollutants below this order may exist. If these contaminants interfere with the detection of target compounds, the column should be pre-cleaned.
Shanghai Haozhuang has a recognized team of experts in the industry and first-class scientific and technological talents, with a deep understanding and mastery of scientific instrument technology, serving customers!

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