IT-SPME-HPLC Applied To Analysis Of The Nitro Polycyclic Aromatic Hydrocarbons

Generally, over 80% of analysis time is consumed on the sampling and sample preparation processes including concentration, extraction, fractionation and isolation of analytes. Therefore, sample preparation has been regarded as the primary bottleneck of the analytical process, especially for analysis of low and trace components. Solid-phase microextraction(SPME) in sample pretreatment method has a very good development prospect due to its advantages such as simple operation,rapidity, sensitivity, high efficiency, simultaneous sampling and enrichment, etc..In this paper we used poly butyl methacrylate monolithic column as sample pretreatment device, and coupled to high performance liquid chromatography(HPLC)- laser induced fluorescence detector(LIF) to analyse three kinds isomers of nitro-polycyclic aromatic hydrocarbons(NPAHs). The details of this study are as follows:First of all, in order to improve the detection sensitivity and utilize the high selectivity of fluorescence detector, we need to reduce the NPAHs to amino polycyclic aromatic hydrocarbons(APAHs) which have strong fluorescence. We chose catalytic hydrogenation to reduce NPAHs. In the reduction experiments, we achieved higher efficiency of reduction through optimized reduction methods, catalyst species,reducing agent, reduction temperature, reduction time and other conditions. Reduction efficiency of the three kinds of Dinitropyrenes(DNPs) was between 98.39% and118.30%. And then, UV initiation method was used to prepare organic polymer monoliths. We optimized the various ratios of pre-aggregated solution to achieve high specific surface area and permeability. In this process, we made a homemade capillary rotating device which was used for UV polymerization preparation of micro/nano particles copolymerized monolithic capillary column. It can be used to overcome the problems of traditional UV polymerization preparation methods, such as micro/nano particles deposition in polymer and pre-aggregated solution by uneven UV irradiation.It can improve the dispersion of micro/nano particles in polymer. Moreover, it also can improve the uniformity and analytical performance of the prepared monolithic column. Next, we used optimal extraction column to extract reduced product Diaminopyrenes(DAPs), and the optimal extraction efficiency could reach 84.28%.Finally, we prepared packed separation column, and the three kinds of DAPs were separated and detected using HPLC-LIF system. We optimized concentration ofmobile phase, flow rate and p H value to achieve the best efficiency of separation. The baseline separation was obtained with the resolution of 1.23-2.71, number of theoretical plates of 8845.90-11930.58 and height equivalent to a theoretical plate of83.82-113.05 μm.This paper successfully established an IT-SPME-HPLC system, which can analyze NPAHs samples accurately. Each step of this system was optimized respectively, in order to achieve high accuracy analysis. The future work of the experiment is to make this system integrate on the microfluidic chip, so that we can achieve miniaturization and integration of IT-SPME-HPLC system.