Stanley E. Manahan

Development of a passive, in situ, integrative sampler for hydrophilic organic contaminants in aquatic environments

Increasingly it is being realized that a holistic hazard assessment of complex environmental contaminant mixtures requires data on the concentrations of hydrophilic organic contaminants including new generation pesticides, pharmaceuticals, personal care products, and many chemicals associated with household, industrial, and agricultural wastes. To address this issue, we developed a passive in situ sampling device (the polar organic chemical integrative sampler [POCIS]) that integratively concentrates trace levels of complex mixtures of hydrophilic environmental contaminants, enables the determination of their time-weighted average water concentrations, and provides a method of estimating the potential exposure of aquatic organisms to the complex mixture of waterborne contaminants. Using a prototype sampler, linear uptake of selected herbicides and pharmaceuticals with log K(ow)s < 4.0 was observed for up to 56 d. Estimation of the ambient water concentrations of chemicals of interest is achieved by using appropriate uptake models and determination of POCIS sampling rates for appropriate exposure conditions. Use of POCIS in field validation studies targeting the herbicide diuron in the United Kingdom resulted in the detection of the chemical at estimated concentrations of 190 to 600 ng/L. These values are in agreement with reported levels found in traditional grab samples taken concurrently.

Fate of heavy metals and radioactive metals in gasification of sewage sludge

The fates of radioactive cadmium, strontium, cesium, cobalt, arsenic, mercury, zinc, and copper spiked into sewage sludge were determined when the sludge was gasified by a process that maximizes production of char from the sludge (ChemChar process). For the most part the metals were retained in the char product in the gasifier. Small, but measurable quantities of arsenic were mobilized by gasification and slightly more than 1% of the arsenic was detected in the effluent gas. Mercury was largely mobilized from the solids in the gasifier, but most of the mercury was retained in a filter composed of char prepared from the sludge. The small amounts of mercury leaving the gasification system were found to be associated with an aerosol product generated during gasification. The metals retained in the char product of gasification were only partially leachable with 50% concentrated nitric acid.

Hazardous chemicals from coal conversion processes

It is evident that some health hazards are to be expected with the advent of a large-scale coal-conversion industry. The paper deals with the need to investigate the hazards associated with carcinogenic polycyclic aromatic hydrocarbons, aromatic amines, toxic metals and organometallic compounds. Although these processes look promising with respect to the removal of traditional pollutants, it is likely that they will produce chemicals that have not even been identified or characterized with respect to their health and environmental effects. The development of any new technology requires investigation of toxicological and environmental impacts of that technology. This is especially true of coal-conversion processes because of the diverse nature of the raw material. In order to prevent any delay in the large-scale development of this industry, a major effort should be made now, before developments proceed beyond the pilot-plant stage, to eliminate potential hazards that may be imposed upon the environment and the health of personnel.

Atomic Absorption Detector for Liquid-Liquid Chromatography

Abstract A detector system specific for the measurement of chelating agents and applicable to liquid-liquid chromatography has been developed. A solution containing the chelating agent is passed over a short column of chelating ion exchange resin in the copper form, and directly into the aspirator of a recording atomic absorption spectrophotometer set to measure copper. A quantity of copper proportional to the quantity of the chelating agent is stripped from the column and recorded as a peak. Precision and accuracy compare with normal atomic absorption techniques, with an average mean standard deviation of 3%, and a corresponding accuracy. The detection limit for this method is 5x10-7 millimoles of EDTA or NTA. Determinations are rapid and reproducible in solutions having a pH in the range of 4 to 9. The role of interfering ions is considered. The applicability of the method as a specific detector system for liquid-liquid chromatographic separations of chelating agents is discussed. Recovery of chelating ...

Atomic Absorption Detector for Chromium Organometallic Compounds Separated by High Speed Liquid Chromatography

Abstract Atomic absorption spectroscopy (AAS) has been demonstrated to be a metal-specific detector for chromium organometallic compounds separated by high pressure liquid chromatography (HPLC). Column effluent from the HPLC instrument was fed directly to the aspirator of the atomic absorption instrument set to record absorption due to chromium. Well defined peaks were obtained. In addition to being specific for a given metal, the method is free of some of the constrictions placed upon conventional ultraviolet absorption and refractive index detectors commonly used with HPLC. For example, solvents which absorb strongly in the ultraviolet may be employed and there is no need to use expensive spectroquality solvents. The method promises to be particularly useful for the analysis of specific organometallic compounds found in liquefied coal and shale oil.

Low-temperature precipitation titration of perchlorate and tetrafluoroborate with tetraphenylarsonium chloride and ion-selective electrodes

Abstract Perchlorate and tetrafluoroborate have been determined at low concentrations by precipitation titration with tetraphenylarsonium chloride, the appropriate anionselective electrodes being used to follow the course of the titration potentiometrically. A low temperature, 2°, was employed to sharpen the titration curves, thus resulting in greater accuracy and lower limits of analysis. As little as 0.05 mmol of perchlorate and 0.25 mmol of tetrafluoroborate have been determined to within 1% relative accuracy. These limits could easily be extended by a factor of 10 by using a miniaturized titration apparatus.

Stabilized Liquid Membrane Device (SLMD) for the Passive, Integrative Sampling of Labile Metals in Water

A stabilized liquid membrane device (SLMD) is described forpotential use as an in situ, passive, integrative samplerfor cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead(Pb), and zinc (Zn) in natural waters. The SLMD (patent pending)consists of a 2.5-cm-wide by 15-cm-long strip of low-density polyethylene (LDPE) layflat tubing containing 1 mL of an equalmixture (v/v) of oleic acid (cis-9-octadecenoic acid) and EMO-8Q (7-[4-ethyl-1-methyloctyl]-8-quinolinol). The reagentmixture continuously diffuses to the exterior surface of the LDPE membrane, and provides for sequestration of several divalent metals for up to several weeks. Depending on samplerconfiguration, concentration factors of several thousand canbe realized for these metal ions after just a few days. In addition to in situ deployment, the SLMD may be useful for laboratory determination of labile metal species in grab samples. Methods for minimizing the effects of water flow onthe sampling rate are currently under investigation.

Measurement of Chelating Agent Levels in Media with High Concentrations of Interfering Metal Ions

Abstract An ion-exchange method for the measurement of levels of chelating agents in media with high levels of metal ions has been developed. The test solution is passed through a specially prepared ion-exchange column, which both removes metal ion interferences, and places the chelating agent in the copper form. The copper levels in the column effluent are then measured by flame atomic absorption methods, the copper levels corresponding in a 1:1 ratio to the levels of chelating agent in the sample. The detection limit for this method is on the order of 1 ppm copper equivalent chelating capacity, and is applicable in situations where the interfering metal ions are at concentrations in the range of 10−2 M. The method is reproducible in the pH ranges of 4 to 9 Precision and

An Atomic Absorption Analysis Method for Cyanide

Abstract An atomic absorption analysis procedure for cyanide has been developed. The procedure is based upon the solubilization of copper(II) from a basic copper carbonate in an alkaline medium. The amount of copper complexed by the cyanide ion is determined by atomic absorption and a calibration curve is constructed concurrently. The stoichiometry of the cyanide-copper complex is 3:1, implying formation of the complex ion Cu(CN)− 3, with no formation of CuCN observed at the low concentration of cyanide used. The method is used primarily for analyzing low levels of cyanide; the sensitivity of the method extending down to 2.0 × 10−5 M CN−. The most likely interference, iron, is considered. Finally, recovery of cyanide from spiked samples is demonstrated.

Kinetics of the reactions of EDTA and coal humic acid with CuO

Abstract The kinetics of cupric ion extraction from solid cupric oxide by two chelating agents was studied. EDTA (disodium ethylenediaminetetraacetic acid) and humic acid (a natural product) were both observed to solubilize CuO at a rate largely independent of chelating agent concentration. A rate law was derived which explained deviations from pure zero order kinetics in terms of surface binding of H2O, OH−, chelating agents and copper chelates to CuO. Through application of the equation, it was shown that humic acid (H.A.) and copper humate (Cu-H.A.) inhibited ionic dissolution of CuO and that EDTA activated the dissociation process. Cu-EDTA had little effect on the rate of dissociation. The change in dissociation rate with varying pH, concentrations of chelating agent and copper chelate, etc. was interpreted in light of the probable effect of each in shifting the equilibrium of bound species on the CuO surface. The initial dissociation rate of CuO in the presence of either chelating agent was on the order of 10−7 m/1-sec in the pH range 9−5.