Activation Process of SPE Cartridge
Hawach solid phase extraction cartridges are designed for sample pretreatment to remove or minimize sample matrix and other interferences to “clean up” a sample prior to analysis. This procedure can also concentrate an analyte to achieve the desired sensitivity range of an analytical method. Compounds are isolated from complex mixtures by proper selection of a variety of sorbent chemistries.
It is mainly used for sample pretreatment of various foods, agricultural and livestock products, environmental samples and target compounds in biological samples. Solid phase extraction technology has been widely used in many national standards (GB/T) and industry analysis standards.
The simplest solid phase extraction can be done manually, by attaching a syringe to the upper end of the SPE cartridge and extruding the liquid from the extraction cartridge by squeezing the syringe. Alternatively, a batch sample may be subjected to a solid phase extraction operation using a positive pressure or negative pressure solid phase extraction apparatus.
With the development of technology and the increase in the number of samples, more and more analytical laboratories began to use automated solid phase extraction, especially multi-channel solid phase extraction to process batch samples.
Configuration of SPE Cartridge
The common solid-phase extraction cartridge is mainly used as a needle tube type device with polyethylene as a material, and two pieces of a plug piece with the material of polypropylene or glass fiber are arranged in the device, and a certain amount of chromatographic adsorbent (filler) is filled in the middle of the two plug sheets. The upper end of the solid-phase extraction column is open, the lower end is a liquid outlet, and the liquid is discharged from the outlet after passing through the adsorbent. The size of the solid-phase extraction column can be divided into 1 mL,3 mL,6 mL,10 mL,15 mL,20 mL,30 mL,60 mL, and the like based on the volume of space above the classical solid-phase extraction column filler.
The capacity of SPE Cartridge
The capacity of solid phase extraction cartridge refers to the adsorption capacity of solid-phase extraction cartridge packing. For solid phase extraction cartridge based on silica gel, the capacity of the column is generally 1 ≤ 5 mg/100 mg. The capacity of bonded silica gel ion-exchange adsorbents is expressed by meq/g, that is, the capacity per gram of packing is X mg equivalent.
Effect of Activation
The solid phase SPE cartridge should be eluted with an appropriate solvent before the sample is extracted to keep the absorbent moist and the target compound or interfering compound can be adsorbed. The solvents for the activation of solid phase extraction cartridge are different in different modes.
Types of activating Adsorbents
Weak polar or non-polar adsorbents used in reverse solid phase extraction usually washed with water-soluble organic solvents, such as methanol, and then washed with water or buffer solvents.
Polar adsorbents for positive phase solid phase extraction, usually eluted with the organic solvent in which the target compound is located.
The adsorbents used for ion exchange solid phase extraction can be eluted with sample solvents when they are used in non-polar organic solvents, and when they are used for samples in active solvents, after leaching with water-soluble organic solvents, they can be eluted with appropriate PH values and aqueous solutions containing certain organic solvents and salt.
In order to keep the adsorbents in the solid phase cartridge moist after activation and before the sample is added, the appropriate solvent should be maintained on the adsorbents after activation treatment.