ABSTRACT
Naturally occurring diatomaceous earth (diatomite) has been tested as a potential sorbent for Pb(II) ions. The intrinsic exchange properties were further improved by modification with manganese oxides. Modified adsorbent (referred to as Mn-diatomite) showed a higher tendency for adsorbing lead ions from solution at pH 4. The high performance exhibited by Mn-diatomite was attributed to increased surface area and higher negative surface charge after modification. Scanning electron microscope pictures revealed a birnessite structure of manganese oxides, which was featured by a plate-like-crystal structure. Diatomite filtration quality was improved after modification by manganese oxides. Good filtration qualities combined with high exchange capacity emphasised the potential use of Mn-diatomite in filtration systems.
Subject(s)
Diatomaceous Earth/chemistry , Immunosorbents/chemistry , Lead/chemistry , Manganese Compounds/chemistry , Oxides/chemistry , Water Purification/methods , Adsorption , Filtration , Hydrogen-Ion Concentration , Microscopy, Electron, ScanningABSTRACT
A method is described for the determination of mercury by potentiometric stripping analysis. The analyte, Hg(2+), is employed for oxidizing a fixed amount of cadmium, previously reduced and amalgamated at a thin mercury film preplated on a glassy carbon electrode. The cadmium stripping signal correlates well with the amount of Hg(2+) added. Correlation coefficients of 0.9971 and 0.9960 were obtained for the two working ranges: (25 ng-2.5 microg) and (5.0-50) microg Hg(2+), respectively, in spiked water samples. The method was investigated with respect to precision and accuracy by spiking a natural water sample with 25 microg Hg(2+).Nine replicate determinations gave a mean value of 24.8 microg with a standard deviation +/-0.31 microg. The 95% confidence limit of the mean suggested the absence of systematic errors. Using the highest possible sensitivity, detection limits of 2.0 ng (167 ng/l) and 0.5 ng (4.2 ng/100 ml of whole blood) were obtained in water and blood samples, respectively. The applicability of the method was successfully extended to include the more complex matrices after recording a zero blank from authentic samples spiked with Cd(2+) (25 microg).The described PSA procedure is a simple and rapid method compared with the cold-vapor technique, with a 5.2% and 4.9% RSD, respectively.
ABSTRACT
A lead poisoned adult (blood lead level 384 micrograms/dL) had a specific urinary porphyrin profile of elevated porphyrins including coproporphyrin III and 5-carboxylic acid derivatives. A multilinear gradient elution, modified with an ion-pair and a reversed phase column were employed for the separation of the diagnostically important porphyrin isomers. Fluorescence detection enhanced both sensitivity and selectivity. Both compounds were restored to normal levels following two courses of meso 2,3-dimercaptosuccinic acid: 90 mg/kg/d x 5 d at one month intervals. The decrease of clinical symptoms was associated with increase of delta aminolevulinic acid dehydratase from 53 to 230 U/mL blood and hemoglobin from 8.4 to 12.7 g/dL. Blood lead decreased from 384 to 24 micrograms/dL, urine lead from 1286 to 188 micrograms/L and urine coproporphyrin III from 5712 to 25 micrograms/L.
