://Commonly Used Solid Phase Extraction Procedure

Commonly Used Solid Phase Extraction Procedure

Reversed phase packing – This type of packing includes the most widely used reversed-phase packing C18. In addition, C8, C2 cyclohexyl and phenyl bonded phases are also available and offer different selectivity. Generally, non-polar to moderately polar compounds remain on the reverse phase packing in a polar matrix. Such fillers require equilibrium adjustment with an organic solvent and subsequent aqueous solution prior to use. The elution of moderately polar compounds is usually methanol, and the elution of non-polar compounds requires less polar solvents.
Reverse SPE operation steps:
A. Adjustment First rinses the packing with 3-5ml methanol. Rinse the packing with 3-5 ml of water or buffer. Do not allow the packing to drain before loading.
B. Loading The sample is applied to the top of the packed bed. The sample was pushed or pumped through the packing at a rate of 1-5 mL/min. If the desired sample is not retained, collect the sample for analysis.
C. Flush If the desired sample is retained, use a polar solvent to flush out the weakly retained interference.
D. Elution The desired compound was eluted using 1-2 mL of a non-polar solvent. Samples were collected for analysis.

Normal phase fillers – silica gel, Florisil, amino, cyano, diol, and alumina are available. The normal phase filler retains polar compounds that are soluble in the non-polar medium. The equilibrium is adjusted using a non-polar solvent and eluted with a more polar solvent. The basic compounds are retained on the silica gel filler, and very polar compounds such as carbohydrates are irreversibly retained in the silica filler. In this case, a diol or amino bonded phase is a better choice.
Normal phase SPE operation steps:
A. Adjustment Flush the packing with 3-5mL of non-polar solvent.
B. Loading The sample is applied to the top of the packed bed. The sample was pushed or pumped through the packing at a rate of 1-5 mL/min. If the desired sample is not retained, collect the sample for analysis.
C. Flush If the desired sample is retained, use a non-polar solvent to flush out the weakly retained interference.
D. Elution The desired compound was eluted using 1-2 mL of a polar solvent. Samples were collected for analysis.

Ion exchange packing – both strong anion (SAX) and strong cation (SCX) exchange groups are available. The anion/cation exchange in the sample with the anion/cation on the resin respectively causes the anion/cation to remain on the relevant resin. The elution uses a high ionic strength buffer (0.1M – 0.5M) or the compound in the sample is no longer charged by changing the pH of the eluent. The backbone of these resins is typically a styrene-divinylbenzene copolymer, and an increase in the organic solvent content of the sample will result in a decrease in exchange capacity.
Ion exchange SPE operation steps:
A. Adjustment Wash the packing with 5mL deionized water or low ionic strength buffer solution (0.001M-0.01M).
B. Loading The sample is applied to the top of the packed bed. The sample was pushed or pumped through the packing at a rate of 1-2 mL/min. If the desired sample is not retained, collect the sample for analysis.
C. Flush If the desired sample is retained, rinse off the weakly retained interference with deionized water or a low ionic strength buffer solution.
D. Elution The desired compound is eluted using 1-5 mL of a high concentration of salt solution (0.1-0.5 M), or the pH of the elution buffer is changed so that the sample compound is no longer ionized. Samples were collected for analysis.

2019-04-03T01:49:01+00:00September 14th, 2018|