1Solid phase extraction instrumentCore principles and device composition

Solid phase extraction (SPE) selectively adsorbs target compounds from liquid samples using solid adsorbents, achieving separation from the matrix and interferents, and then enriching the target compounds through elution or desorption. Its core devices include:

Solid phase extraction column: composed of medical polypropylene column tube, porous polypropylene sieve plate (20 μ m), and packing (40-60 μ m or 80-100 μ m), common specifications include 100mg/1ml, 500mg/3ml, etc.

Vacuum system: including vacuum pump, pressure gauge, buffer bottle, used to provide negative pressure to facilitate sample passage through the extraction column.

Collection device: test tube rack (12/24 adjustable), collection bottle, used for collecting eluent.

Auxiliary components: large volume sampler, StopCock valve (precise control of flow rate), anti cross contamination device.

2、 Preparation before operation: Details determine success or failure

Environment and Safety

Ensure that the control panel is stable, free from water accumulation, acid and alkali corrosion, and kept away from direct air conditioning to prevent instrument aging.

Wear protective gloves and goggles, verify the laboratory voltage regulator, and check the capacity of the waste liquid collection bottle.

Sample and reagent preparation

Sample processing:

Liquid phase sample: direct injection.

Solid samples: Dissolve and filter (0.45 μ m filter membrane), centrifuge or dilute to appropriate concentration.

Reagent selection:

Extraction column: Select the packing material based on the properties of the target substance (e.g. C18 column is suitable for non-polar substances, NH2 column is suitable for acidic compounds).

Activation solvent: Reverse phase column with methanol (6 times column volume) → water (4 times column volume); The positive phase column uses the organic solvent in which the sample is located; Use 3-5ml of deionized water for the ion exchange column.

Equipment inspection

Check the output pressure of the vacuum pump (<0.1MPa, negative pressure>-0.09MPa), and confirm that there are no foreign objects in the sealing gaskets of each channel.

The independent control channel needs to confirm its opening status in advance to avoid abnormal pressure.

3、 Operation steps: Standardized process and key parameters

Activated extraction column

Purpose: To remove impurities and create a suitable solvent environment.

Method: Methanol (6 times column volume) and water (4 times column volume) were sequentially passed through the extraction column at a flow rate of 0.5-1ml/min, and the surface of the sieve plate was observed to be a horizontal smooth infiltration surface.

sampling

Method: Slowly add the sample solution to the extraction column and control the total sample loading to ≤ 2000 times the column volume (e.g. 1ml column can handle up to 2L of sample).

Flow rate: ≤ 5ml/min for biological samples, ≤ 15ml/min for industrial wastewater, pause and check if the hydraulic gauge pointer is stable in the green zone every 300ml passed.

Collection: The target compound starts to be collected when it flows out with the sample base solution, and impurities are retained on the column.

Rinse (remove impurities)

Purpose: To remove interfering substances and preserve the target object.

Method: Pass 5ml of 0.1% acetic acid aqueous solution through the column three times at the same flow rate as the loading stage.

elute

Objective: To elute the target substance with a small volume solvent.

Method:

Single system elution: 75% 0.35mol/L methanol+25% acetone mixed solution, flow rate reduced to 65% in the initial stage.

Dual system elution: alternate the use of two solvents and record the receiving tube numbers for each group.

Elution volume: Avoid excessive volume (can be controlled by reducing solvent dosage or shortening time).

post-processing

Eluent treatment: drying (nitrogen blow drying), redissolution (methanol/water), or concentration (rotary evaporation).

Column regeneration: Rinse with distilled water for 30 minutes → maintain with 60% methanol for 45 minutes, remove and store in a vacuum dryer.

4、 Post operation maintenance: Extend equipment lifespan

Cleaning and Storage

Cleaning: Rinse the pipeline with deionized water or cleaning agent until there is no residue.

Storage: Moisture proof, dust-proof, and light proof. If not used for a long time, the automatic drainage mode should be activated to eliminate the liquid in the pump. The self check program should be started every month to prevent seal adhesion.

Data recording and shutdown

Register the machine time, model code, and sample pH parameters in the 'Usage Registration Book'.

Turn off the main power control circuit breaker and check the status of the shutdown indicator light.

5、 Common Problems and Solutions

Extraction column blockage

Reason: The sample contains particles or loose fillers.

Solution: Backwash with methanol (low flow rate), if ineffective, replace the extraction column.

Poor elution effect

Reason: Improper selection of elution solvent or excessive flow rate.

Solution: Optimize the elution conditions (such as increasing the proportion of methanol) and reduce the flow rate to 65% in the initial stage.

Abnormal pressure

Reason: The sealing gasket is leaking or the channel is not closed.

Solution: Check the flatness of the sealing gasket and close any unused channels.