The Study Of Knotted Reactor Preconcentration On-line Heating Acidity Eluent Coupled With Atomic Spectrometry

In this thesis, a flow injection on-line sorption preconcentration and separation in a knotted reactor (PTFE) was coupled to atomic spectrometry for determining trace elements. The experimental devices were set up; experimental conditions were investigated and analytical methods were developed to determine trace elements in real samples.Sample preconcentration and separation were the key factors for detemining trace elements. Off-line procedures operated in the batch mode are time-consuming and laborintensive, require large sample volumes, and suffer great risks of contamination and analyte loss. With on-line operation using flow injection ( FI ) techniques, the drawbacks of batchwise operation can be overcome to a great extent, while preconcentration and separation can be further enhanced. FI on-line preconcentration and separation techniques for atomic spectrometry were introduced importantly. Choice of a proper eluent is critical to the successful coupling of FI on-line KR adsorption preconcentration to atomic spectrometry. Conventional organic reagent (eg: methanol, ethanol) eluent was unfit for determination in atomic spectrometry. Moreove, Atomic fluorescence was prone to be quenched by organic reagent. Electromagnetic induction heating technique was coupled to FI on-line KR preconcentration and separation for the first time. HNO₃ heated by Electromagnetic induction heating technique was used as eluent to remove the absorbed complex from the KR. The analytical method was developed to determine trace elements in real samples.In chapter two, flow injection on sorption preconcentration and separation in a knotted reactor (PTFE) was coupled to flame atomic absorbance spectrometry for determining trace cadmium in river water. Heating HNO₃ was used as eluent for the first time. Oil was used as heater. The effects of several experimental parameters of the proposed method were optimized in this system. The tolerance of coexisting ions as Zn²⁺,Cu²⁺,Fe³⁺,Hg²⁺,Ni²⁺,Se⁴⁺,As³⁺ was carefully examined in this system.The proposed method was of high sensitive and simple. It was successfully applied to the determination of cadmium in river water. In chapter three, a flow injection on sorption preconcentration and separation in a knotted reactor (PTFE) was coupled to cold vapor atomic fluorescence spectrometry for trace mercury in mineral water. Knotted reactor was fabricated by polytetrafluoroethylene (PTEF) (150cm,i.d./o.d.=0.50mm/1.05mm) that was covered by stainless steel wire. 20% HNO₃ heated by Electromagnetic induction heating technique was used as eluent to remove the absorbed Hg-DDTC from the KR, then mixed with KBH4 to form vapor mercury and determined on-line by cold vapor atomic fluorescence spectrometry (CV-AFS).20% HNO₃ was employed not only as the efficient eluent but also the required medium for subsequent hydride generation.Using 20% HNO₃ instead of organic as eluent, the proposed method is characterized by simple, easy operation and environmentally friendly. Under the optimal experimental conditions, the sample throughput were 30/h with enhancement factors of 35.The detection limit of mercury was 2.0ng/L.The precision (RSD, n=11) was 2.2% at the 0.1μg/L Hg²⁺ level.