Operative Step for C18 SPE Cartridge

Some SPE cartridges use reverse phase (nonpolar) silica gel as the matrix and the reverse filler is some kind of nonpolar adsorbent that extracts the nonpolar chemical compounds from the polar matrix. As for the reverse phase adsorbent, its extraction ability will go down when the non-polarity of the eluent increases.

In specific, the C18 SPE Cartridge is the bonding silica gel adsorbent with the strongest hydrophobicity. Because it has extremely strong extraction power to the nonpolar chemical compound, it is widely applied as the solid phase extraction adsorbent. Moreover, the C18 SPE Cartridge is normally considered as having the widest range of extraction among all kinds of bonding silica gel adsorbent, because it can extract most of the organic matter in the liquid matrix. When analyzing micro molecules and medium molecules, the C18 SPE Cartridge can be applied for removing salt in the liquid matrix before the ion exchange, because salt can go through the adsorbent without any reservation.

HAWACH SPE cartridges are available in 1ml, 3ml, 6ml and12ml and the packing materials include four major types: silicone bonded matrix, polymer matrix, adsorption matrix, and special column. The silicone bonded matrix includes reversed phase C18 SPE cartridge, C18-ne, C8; normal phase Silica, Diol, CN; ion exchange SCX, SAX, NH2, PRS, PSA; mixed mode C8/SCX, C8/SAX. The polymer matrix includes HLB, MCX (PS/DCB), MAX (PS/DCB), WCX (PS/DCB), and WAX (PS/DCB). The Adsorption matrix contains alumina (AI203), graphitized carbon black (GCB), and Florisil pesticide residue. As for the special column, it is for the azo dye detection column, etc.

In addition, the C18 SPE Cartridge does not resist macromolecule, so it is also suitable for the desalination of protein. On the whole, the C18 SPE Cartridge can effectively separate protein, polypeptide, or nucleotide in the laboratory.
C18A SPE Cartridges

Sample Treatment Process

Sample treatment is the most commonly used step in C18 SPE cartridge analysis. C18 cartridge can reduce the sample processing time and can be used as follows:

1. Purification: the packing in the solid phase cartridge will adsorb the compounds or the impurities in the sample. Thus, when the sample flows out, the selected compound is left on the cartridge.

2. Micro-extraction or concentration: when the amount of analytical material is below the limit of the method, the analyte can be concentrated.

3. Separation: gradient eluting, extracting the sample, and increasing the sample concentration.

4. Dissolution exchange: if the sample is insoluble, the appropriate solvent can be used to adsorb and wash the analytical substance.

Factors for Affecting Separation

The sample separation effect is related to the flow rate and upload. The sample size of the SPE cartridge depends on the sample structure, the volume of the solution, the polarity of the solvent, and the adsorption performance of the sample. Moreover, if the flow rate of the sample is too fast, the effective component may not remain in the adsorbent, so the flow rate is important in the activation process of the SPE cartridge.

Operation steps of C18 cartridge

The following are the five steps when using a C18 cartridge, each of which is different but not required.

Step 1: Prepare the sample-The sample can be either liquid or air phase. If it is a solid phase, the sample must be decomposed or extracted before the column.
Step 2: Activation or equilibration of the column-For reversed phase columns such as C18, activation is necessary. The strong column is used to wet the column’s stationary phase, and then the weak column is used to equilibrate and activate the column.
Step 3: Load– Load the sample into the extraction column. At this point, the packing in the solid phase extraction cartridge will adsorb the compound of interest or the impurities in the sample. Thus, when the sample flows out, the selected compound (including impurities) is left in the extraction column.
Step 4: Flushing–The impurities are rinsed with a rinse that is strong enough to elute the impurities and weak enough to retain the compound of interest.
Step 5: Eluting the compound of interest–Use a solvent to elute the compound adsorbed on the extraction column in the solution.

Usage of C18 SPE cartridge

Sample processing is the most common step in the analysis. C18 SPE cartridge is a sample-processing solid phase extraction device that is easy to use and recyclable. The C18 SPE cartridge reduces sample processing time and can be used as follows:

Purification: The packing in the SPE cartridge adsorbs the compound of interest or impurities in the sample. Thus, when the sample flows out, the selected compound (including impurities) is left in the extraction column.

Microextraction or concentration: The analyte can be concentrated when the amount of analyte is below the method limit.

Separation: Gradient elution based on different polarities of the sample, extraction of samples, and increase of sample concentration.
Dissolution exchange: If the sample is poorly soluble, the analyte can be adsorbed and eluted through the cartridge with a suitable solvent.

Factors affecting separation

The sample separation effect is related to the flow rate and upload. Here are suggestions:

(1)Flow rate of C18 – if the sample flow rate is too fast, the active ingredient may not remain in the adsorbent, so the flow rate is 5 to 10 ml minutes when the column is activated. When loading and eluting samples with other ion exchange columns, the flow rate of the crucible is 0.2~1ml minutes, and the flow rate of other small columns is 2~10ml minutes.

(2)Sample loading – the loading of the cartridge depends on sample structure, solution volume, solvent polarity, adsorbent type and amount, and sample adsorption performance.

Storage of C18 cartridge

The small column can be stored in a sealed plastic bag for a long time. If the unused column is placed in an open plastic bag, the air in the bag should be drained, the bag mouth should be tightened twice, and sealed with sealing tape. Store it in a desiccator.