Competing ligand exchange-solid phase extraction method for the determination of the complexation of dissolved inorganic mercury (II) in natural waters.
نویسندگان
چکیده
A method employing dual competitive ligand exchange followed by solid phase extraction (CLE-SPE) for characterizing the complexation of inorganic Hg(II) in natural waters is described. This method employs parallel use of two competing ligands: diethyldithiolcarbamate (DEDC), which forms hydrophobic complexes with Hg(II), and thiosalicylic acid (TSA), which forms hydrophilic complexes with Hg(II). Inorganic mercury complexed by natural and competing ligands are separated based on hydrophobicity using C18 solid phase extraction columns. Data modeling allows for the calculation of the concentration and conditional stability constants of natural ligands capable of complexing Hg(II) in both the operationally defined hydrophilic and hydrophobic fractions. The use of multiple ligand concentrations, and thus multiple analytical windows, to characterize different ligand classes within both of these two fractions is described. Studies of the kinetics of the ligand exchange involved, potential for changes in the stability of natural ligands during freezing and thawing, potential breakthrough during solid phase extraction, as well as the method's precision and estimation of error, are presented and discussed. Results from the application of the method to natural freshwaters demonstrated that in the limited samples collected over 99.99% of the ambient inorganic mercury is strongly complexed by ligands with conditional stability constants (K(HgL)(cond), Hg2+) on the order of 10(30), values similar to that of reduced sulfur ligands. At ambient conditions 85-90% of the mercury exists in hydrophobic complexes in these freshwaters, but strong Hg-binding ligands exist in both the hydrophobic and hydrophilic fractions.
منابع مشابه
Cold Vapor Atomic Absorption Determination of Hg in Crude Oil and Gasoline Samples after Solid Phase Extraction Using Modified Disks
A facile and highly efficient method have been developed for the preconcentration of the mercury content in crude oil and gasoline samples after digestion with microwave-assisted digestion. Octadecyl silica membrane disk has been modified by the recently synthesized triazene ligand, (E)-1-(2-ethoxyphenyl)-3-(4-nitrophenyl) triaz-1-ene (ENT), then the modified membrane was used for the preco...
متن کاملMicelle Mediated Preconcentration of Mercury in pH Controlled Mode for Trace Analysis
A micell-mediated phase separation method for preconcentration of ultra-trace quantities of mercury as a prior step to its determination by UV-Vis spectrophotometry has been developed. The method is based on Hg(II)-dithizone complex formation in alkaline aqueous solution, and extraction of this Hg(II)-dithizone secondary complex into the surfactant-rich phase of the non-ionic surfactant oct...
متن کاملExtraction sorbent with nanographene with aminopropyltriethoxysilane for the preconcentration (APTES) on surfactant coated C18 of Cd(II) in water
Solid phase extraction (SPE) or liquid-solid extraction is poplar and growing techniques that areused to sample preparation for analysis. Metal nanoparticles have been studied for decades, and this is due to the properties that these materials do not have in bulk state. In nanoscale materials, the numbers of surface atoms is high and hence, have significant surface effects. A novel, simpl...
متن کاملSolid-phase Extraction Using Modified Carbon Nanotube and Cupferron Ligand for Preconcentration and Determination of Trace Amounts of Copper in Real Samples
A solid phase extraction procedure for simultaneous separation and preconcentration of traceamounts of Cu+2 ion from various real samples prior to its determination by flame atomicabsorption spectrometry has been developed. The proposed method is based on the utilization ofmultiwalled carbon nanotube in combination with Cupferron ligand as a solid phaseextractant. The influences of the analytic...
متن کاملApplication of Nanoanalysis: Amine-Functionalized Mesoporous Silica nanoparticles for Mercury Speciation in Human Samples
Mercury (Hg) causes hazardous cumulative effects in humans; like central nervous system disorders,hypertension and chromosomal aberrations. Therefore, due to high toxicity and bioaccumulationfactor, mercury determination and speciation in human blood is very important. A sensitive,accurate, precise and inexpensive method was demonstrated for preconcentration and speciationof ultra-trace mercury...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Analytica chimica acta
دوره 598 2 شماره
صفحات -
تاریخ انتشار 2007