Study On Performance Evaluation And Application Of Two Kinds Of Domestic Solid Phase Extraction Materials

Solid phase extraction is a sample pre-preparation process, in this process, the target compounds are adsorbed by solid phase adsorbent which makes them separated with the interferences, and then the targets are eluted by appropriate solvent. Reversed-phase and ion exchange cartridge is a kind of solid phase extraction cartridges, it has two kinds of adsorption mode: reversed phase partition and ion exchange, which makes it have better purification for ionic compounds. There are ion exchange SPE cartridges that are used in the experiments, but most of them are imported materials, which increases the cost of the experiments. Domestic SPE cartridges have diversity species, uneven quality and poor stability which make it difficult to meet the requirements of the experiments. Therefore, it has great practical significance to improve the adsorbent’s enrichment, purification and anti-disturbance ability of realizing the adsorption properties and the mechanism of the adsorbent. So this paper focused on domestic reversed-phase and ion exchange adsorbent, and the main contents and results were as follows:(1) Adsorption capacity of the reversed phase and weak cationic exchange adsorbent(WCX) was studied.①The adsorbent was characterized by SEM and FT-IR which confirmed the adsorbent was synthesized by Polystyrene and Divinylbenzene and there was a –COOH bonded on the polymer. The surface of the adsorbent was smooth, the particles were regularly oriented. There were gaps between the particles which made it easier to adsorb the analytes. The research of the adsorption properties showed that: the saturated adsorption capacity at 30 °C was 200 ng/mg. The adsorption kinetic data were well described with pseudo-second-order model and the equilibrium data were well fitted by Freundlich model. The calculated thermodynamic parameters indicated that the adsorption of melamine on the novel SPE adsorbent was spontaneous and exothermic.②Through the study of pre-preparation, a method of SPE-HPLC-MS/MS to detect 4 kinds of quaternary compounds in rice was established. The targets were extracted by acetonitrile and eluted by acetonitrile/water/acetic acid.The results showed that: in the concentration ranges of 0.005 μg/g ~0.25 μg/g good linear range relationships were shown with the correlation coefficient over 0.99.The spike levels were 0.025 μg/g, 0.05 μg/g, 0.1μg/g, the recoveries were between 61.9%~97.8%, the RSD was lower than 10%, LOQ was between 0.002 μg/g ~0.006 μg/g, and the LOD was between 0.0005 μg/g ~0.002 μg/g.(2) Adsorption capacity of the reversed phase and strong cationic exchange adsorbent(MCX) was studied.①The adsorbent was characterized by SEM and FT-IR which confirmed the adsorbent was synthesized by N-vinylpyrrolidone and Divinylbenzene and that there was a –SO3 bonded on the polymer. The surface of the adsorbent was smooth, the particles were regularly oriented. The gaps between the particles made it easier to adsorb analytes. The research of the adsorption properties showed that: The saturated adsorption capacity at 30 °C was 81.45 μg/mg. The adsorption kinetic data were well described with pseudo-second-order model and the equilibrium data were well fitted by Langmuir model. The calculated thermodynamic parameters indicated that the adsorption of melamine on the novel SPE adsorbent was spontaneous and endothermic and the adsorption process was a chemisorption.②Through the study of pre-preparation, a method of SPE-HPLC-MS/MS to detect melamine in milk was established. Melamine was extracted by acetonitrile and eluted by 5% ammonia in methanol. The results showed that: in the concentration range of 0.05 μg/g~5 μg/g, good linear range relationship was shown with a correlation coefficient of 0.9986. The spike levels were 0.125 μg/g, 0.25 μg/g and 0.5 μg/g, and the recoveries were between 92.3%~102.7%, the relative standard deviations were all below 9.3%, LOQ and LOD were 0.07 μg/g and 0.02 μg/g, respectively. Through the study of pre-preparation, a method of SPE-HPLC-MS/MS to detect 13 kinds of sulfanilamides in milk was established. Sulfanilamides were extracted by perchloric acid at p H 2 and eluted by methanol/water. The results showed that: in the concentration range of 5 ng/g ~100 ng/g good linear range relationships were shown with the correlation coefficient over 0.99.The spike levels were 10 ng/g, 20 ng/g and 40 ng/g, the recoveries were between 63.0%~112.3%, LOQ was between 0.005 μg/g ~0.25 μg/g, and the LOD was between 0.001 μg/g ~0.075 μg/g.Through the study of performance evaluation and application of the two kinds of adsorbent, three methods were established to detect quaternary compounds in rice, melamine in milk and 13 kinds of sulfanilamides in milk by using LC-MS/MS. These methods had high purification, good recoveries and were easy to operate. They can meet the limit of these targets.Comparison experiments were also conducted, the results showed that the recoveries of the targets on these two kinds of novel reversed phase and ion exchange SPE cartridges were close to the same kinds on the market, even better than some of them.