Solid Phase Extraction Coupled With Atomic Adsorption/Optical Emission Spectrometry For Determination Of Elements And Their Specieses In Environmental Samples

Solid phase extraction （SPE） is to absorb the target compound in the liquid sampleswith solid adsorbent, then elute or desorb by heating to separate and enrich the targetcompound. SPE has been frequently used in pharmaceutical, fine chemicals,biological medicine, food and environmental analysis in terms of high efficiency,great reliability, high automation, high enrichment, absence of emulsion, lowconsumption and convenient to combine with other analytical instrumentscharacteristics.The purpose of this work is to develop and research new functional materials, toestablish new technologies of solid phase extraction combine with atomic spectrumfor determination of trace heavy metal and species in environmental samples. Themain contents are as follows:（1） A new method has been developed for pre-concentration and separation of traceCu, Pb and Cd in environmental water samples, followed by flow injection solidphase extraction （SPE） combined with flame atomic absorption spectrometry （FAAS）determination using coal cinder of solid waste as extractant. The parameters of SPEwere optimized systematically. Under the optimun conditions, the limits of detectionare0.6μg L^-1Cu,4.9μg L^-1Pb and1.6μg L^-1Cd with enrichment factors of20³3.3,respectively, and the relative standard deviations （R.S.D.） are0.72%Cu (n=9, C=0.05μg mL^-1),5.0%Pb (n=9, C=0.1μg mL^-1) and3.4%Cd (n=9, C=0.2μgmL^-1), respectively. The proposed method has been successfully applied to thedetermination of Cu, Pb and Cd in environmental water samples.（2） A new, simple, novel and selective method was developed for speciation ofinorganic selenium in environmental water samples, followed by flow injection solidphase extraction （SPE） combine with inductively coupled plasma optical emissionspectrometry （ICP-OES） determination, using sol-gel technique introduced amesoporous zirconia film to coal cinder as new functional materials. The parametersof SPE were optimized in detail. Under the optimun conditions, the detection limits ofSe（IV） is9.0ng L^-1with enrichment factor of100, and the relative standarddeviations （R.S.D.） is3.65%(n=9, C=5.0ng mL^-1). The developed method forassay of Se（VI） is based on subtracting Se（IV） from total selenium by controllingdifferent adsorption medium without employing any oxidation reduction procedure.And the developed method was successfully applied to speciation of inorganic selenium in environmental water samples with satisfactory results.（3） Zirconia coated coal cinder was employed in removal of As（Ⅲ） and As（V） fromaqueous solution followed inductively coupled plasma atomic emission spectrometry（ICP-OES） detection. Effects of pH, initial concentration, reaction time, adsorptionkinetic, thermodynamic and sorption isotherm were investigated in detail. both As（Ⅲ）and As（V） can be quantitatively removed at a wide pH range of2.0to9.0. Theoptimum equilibrium time was1.5h. The process of inorganic arsenic adsorptionfollowed well pseudo-second order rate kinetics and Freundlich isotherm equations.ΔG^o<0, ΔH^o>0and ΔS^o>0revealed the endothermic and spontaneous of the sorptionreaction in natural condition and the randomness increases at the solid-liquidinterface.（4） A new solid phase extraction material SiO₂@thiourea was developed forpre-concentration and separation of trace Pb and Cd in environmental water samples,followed by flow injection solid phase extraction （SPE） combine with inductivelycoupled plasma optical emission spectrometry （ICP-OES） determination. Theparameters of SPE were optimized in detail. Under the optimun conditions, thedetection limits of Pb and Cd are6.36and0.093μg L^-1with enrichment factor of20,respectively, and the relative standard deviations （R.S.D.） are7.5%Pb (n=9, C=0.5μg mL^-1) and1.7%Cd (n=9, C=0.05μg mL^-1), respectively. The proposed methodhas been successfully applied to the determination of Pb and Cd in environmentalwater samples with satisfactory results.