On-site Analysis Technique Research And Application In Water Samples Based On Chemical Preconcentration Thin Sample Method And X-ray Fluorescence Spectum

Analysis of environmental water samples mainly operate in laboratory, which costs much time and money. Portable Energy Dispersive X-ray Fluorescence Spectrometry (P-EDXRF) is a key technology for mineral exploration, mine environment monitoring, as well as on-site determination. The multi-element character, acceptable speed and economy and nondestructive are the most important features that have made X-ray fluorescence (XRF) spectrometry a very mature analytical technique for elemental analysis of a wide variety of samples. The detection limits of conventional XRF direct analysis are in the1～10mg/L range, which are not satisfactory for liquid samples.Therefore a proper preconcentration procedure is needed to decrease the detection limit. Preconcentration methods coupled with XRF have been developed for determination of heavy metals, but a relatively complex operations, less element types can be measured using one pre-concentration strategy, these problems restrict the development of the technique.Firstly, this paper gives an overview of the preconcentration procedures prior to XRF analysis of twenty trace elements (mercury, zinc, lead, cadmium, chromium, manganese iron, cobalt, nickel, selenium, arsenic, strontium, etc)in liquid samples. This paper summarizes the state-of-the-art of the chemical preconcentration methods, discusses the advantages and disadvantages of these preconcentration, presents some new application of these methods and techniques extending the possibilities of XRF for liquid solutions analysis. Resin solid extraction material is proposed as an effect of technolog preconcentration of heavy metals in water samples. This paper introduces the adsorption mechanism of various of anion exchange resin, cationic exchange resin, adsorption resin and chelating resin.Secondly, an on-site-oriented rapid and convenient analysis method of heavy metal ions in aqueous solutions is developed utilizing portable Energy-Dispersive X-Ray Fluorescence (EDXRF) in this paper. The procedure of the experimental in the study is convenient and the price of the instrument and device is economic which suitable for enlarging this application of the on-site field analysis of aqueous solutions. This method skillfully make a thin-layer film sample which solve the pollution problem, simplify the preconcentration steps. The resin film samples can be directly measured by XRF.Tristly, based on preconcentration with purolite S930chelating resin and thin-layer sample preparation technique, the method can determinate trace vanadium manganese, iron, cobalt, nickel, copper, zinc and lead in environmental water samples. After the heavy metal ions being adsorbed by20mg of S-930resin powder for about30min in the pH=4solution, the resin powders are filtrated onto a0.45μn filter to form a thin-layer sample which can be directly measured by EDXRF using a homemade double polypropylene film sample cup. With an amount of100mL of solution, the linear ranges are about10-1000ug/L and the correlation coefficients of the calibration curves were good (R>0.997) for all the eight elements. The lower limits of detection are between10μg/L. Precision tests carried out on multi-element mixed solutions showe that the relative standard deviations (RSD, n=12) are better than5%except for those of Zn and Pb at the concentration level of20μg/L. Most of the recoveries are80-120%with spikes of20μg/L for each elements. The analysis results of DW standard substances and simulation samples are consistent with reference values and theoretical value respectively. A lower detection limit, better stability make the method suitable for a spot investigation and water quality monitoring, assessment of Fe, Co, Ni, Cu, V, Zn, Mn and Pb in heavy metals polluted environmental water. Then, an on-site-oriented rapid and convenient analysis method of V^Cr、Mn、Fe、Co、N1、Cu、Zn/As、Se、Sr、Mo、Cd、Hg、Pb heavy metal ions in aqueous solutions is developed utilizing LSC-100amino acid resin、LSC-200thiourea resin and LSC-500amino phosphonic acid resin.Above all, this method is applied in the field actual sample analysis. More than sixty surface water and underground water samples are obtained and analysed in Heilongjiang and Jiangxi province. The results measured by handheld XRF are consistent with the date of ICP-MS, no obvious systematic error. The preconcentration device and work without external power supply are suitabled for on-site analysis heavy metals and assessed the quality of water samples at the scene of the remote areas.Based on preconcentration device, thin-layer sample preparation technique, these rapid method can realize sampling, processing, data acquisition within twelve hours for about ten samples or within thirty minutes for one samples.Lastly, we are of the opinion that:the trends and future of XRF in trace analysis of liquid samples is the simple, rapid, multi-element and on-site analysis; portable XRF rapid analysis of many kinds of trace elements in liquid samples is of great significance for rapidly, simultaneous analysis of the surrounding water, sediment, soil, rock and atmospheric particulate matter samples in one study area only using XRF.