The cleaning of solid-phase extraction columns is a key step in ensuring experimental accuracy and extending the lifespan of consumables. The following systematically explains the professional cleaning process from four aspects: pre-processing, deep cleaning, special material processing, and storage maintenance:
1、 Basic cleaning process
1. Forward flushing method
-Solvent selection logic: Following the principle of "high → medium → low" polarity gradient. Strong eluent (methanol/acetonitrile) eliminates stubborn residues, then switches to medium polarity solvents (dichloromethane/ethyl acetate) to remove intermediate products, and finally drives away water-soluble impurities with pure water. It is recommended to use 5-10 times the column volume of each solvent to ensure sufficient infiltration.
-Key points for flow rate control: Adopt low-pressure slow mode (≤ 2mL/min) to avoid severe flushing that may cause changes in the compactness of the filling material. Accurate speed control can be achieved with the help of a constant flow pump, and observing the effluent turning from turbid to clear is the standard signal.
2. Reverse shock strategy: For chromatography columns that have obvious blockages, connect them upside down to a solid phase extraction device and use high-pressure nitrogen cylinders to provide pulsed gas flow (0.4MPa). This mechanical action can effectively peel off the adhesive deposits attached to the surface of the sieve plate, and then immediately perform forward flushing to avoid secondary settling.
2、 Targeted pollutant disposal plan
1. Residual biological samples: Protein denaturation precipitation can be carried out using a combination of pH 7.4 phosphate buffer solution and 0.1% Tween-20. The former maintains the isoelectric point to prevent protein conformational changes, while the latter decomposes the adhesive layer by reducing surface tension. If necessary, introduce proteinase K for overnight digestion.
2. Invasion of lipid mixture: Acetone n-hexane (1:1) synergistic system is used, with the former dissolving phospholipid bilayers and the latter disrupting cholesterol crystal domains. The cyclic flushing effect is better under the condition of 60 ℃ water bath.
3、 Special filler regeneration technology
1. Ion exchange column revival technique: When the cationic resin is contaminated with metal chelates, 3mol/L HCl solution (releasing bound Ca ² ⁺/Mg ² ⁺) and deionized water are sequentially injected until neutral. Finally, functional groups are revived using Tris buffer containing 0.1mol/L EDTA (pH=8.0). The anion column needs to be replaced with NaOH instead of HCl for similar operations.
2. Maintenance of graphene composite media: This new type of adsorbent is strictly prohibited from ultrasonic vibration! Recommend using ethanol water (7:3) low-power continuous flushing, supplemented by magnetic stirrer low-speed stirring (<200rpm). After natural air drying, vacuum seal to prevent oxidation and degradation.
4、 Efficiency verification and quality control
1. Standard curve verification: Prepare a series of concentration standard solutions (covering the lower to upper limits of the linear range), and measure the recovery rate after treatment with a clean column. If the recovery rate of the target substance falls within the range of 85% to 115% and the RSD is less than 5%, it indicates that the cleaning procedure is reliable.
2. Blank control experiment: Randomly select washed empty columns for full process simulation operation. GC-MS/HPLC detection should not detect the previously used marker compounds. Pay special attention to residual traces of difficult to volatilize substances.