Barbara Kebbekus

Continuous monitoring of volatile organic compounds in air emissions using an on-line membrane extraction-microtrap-gas chromatographic system

Abstract A method for the continuous monitoring of volatile organic compounds (VOCs) in air using on-line membrane extraction followed by gas chromatographic analysis is presented. The air is passed through one or more hollow-fiber membranes and the VOCs selectively permeate across the membrane into a flow of inert gas such as nitrogen. Before entering the GC column, the VOCs are trapped and concentrated by a microtrap. A concentration pulse of the trapped VOCs is generated by direct electrical heating of the microtrap, which serves as injection for GC separation. Continuous monitoring is done by making injections at fixed intervals of time while the air stream flows continuosly through the membrane module.

Field Determination of Cr(VI) in Water At Low PPB Level

Methods for determining chromium (VI) at the ppb level, in tap water and ground water, were developed. These make use of anion exchange resin beads or anion exchange membrane filters to preconcentrate the Cr(VI) and separate it from interfering cations. The color is developed by reaction with diphenylcarbazide and the quantitation is carried out using a portable UV/Vis spectrometer, in the liquid or solid phase, or by visual color matching. These methods are suitable for use in the field.

Comparison of selected volatile organic compounds during the summer and winter at urban sites in New Jersey

Abstract This paper presents a comparison of summer and winter levels of twenty-five selected volatile organic compounds (VOC) measured as part of the New Jersey project on Airborne Toxic Elements and Organic Substances (ATEOS). Most of the selected VOC were found in the range of 0.01–1.00 ppbv, with the exception of toluene (1–5 ppbv) and benzene (1–3 ppbv). However, peak levels of many compounds increased more than 100 fold during specific pollutant episodes. Generally, VOC levels were higher in the winter than the summer. Day to day variations of measured aromatic VOC showed significant correlations at each site suggesting an area source (motor vehicles), while there was little relationship between chlorinated species. During summer oxidant episodes, selected VOC increased from 2–10 times at Newark and Elizabeth, but not at Camden. In the winter, nocturnal temperature inversions caused levels of selected VOC to increase from 2–3 times seasonal average at all sites.

Emission of Volatile Organic Compounds to the Atmosphere in the Solvent Sublation Process. I. Toluene

Abstract The mass of volatile organic compounds emitted to the atmosphere during solvent sublation was determined experimentally, using toluene as a test compound. It is shown that the emission of toluene to the atmosphere can be significantly reduced by using solvent sublation instead of air stripping under the same experimental conditions. The parameters which affect emission are the air flow rate, the nature and thickness of the organic layer, and the nature and concentrations of the co-solutes. Emissions are reduced as the thickness of the organic layer on the top of the column is increased. The use of decyl alcohol as the layer compound decreases emission to a greater extent than does paraffin oil. The emission of toluene during solvent sublation is further reduced as the air flow rate is lowered. The rate of toluene removal from water in solvent sublation is somewhat higher than in air stripping under the same experimental conditions. The effect of added anionic or cationic surfactants or alcohol wa...

Emission of Volatile Organic Compounds to the Atmosphere in the Solvent Sublation Process. II. Volatile Chlorinated Organic Compounds

Abstract The mass of trichloroethylene, chlorobenzene, and 1,3-dichlorobenzene removed from an aqueous solution and emitted to the atmosphere during solvent sublation was determined experimentally. It was shown that the emission of these compounds in solvent sublation was reduced by 30 to 85% over air stripping under the same experimental conditions. The efficiency of removal of these compounds from water was also studied. The reduction of emissions over air stripping was more effective for the more hydrophobic and less volatile compounds. Emissions are reduced as the thickness of organic layer on the top of the column is increased. The use of decyl alcohol as the layer compound decreases emissions to a greater extent than does paraffin oil. Removal of these chlorinated volatile organic compounds from water by solvent sublation at an elevated temperature of 45°C is significantly faster than at room temperature. However, the emissions to the atmosphere are also increased.

A study of some aromatic and halocarbon vapors in the ambient atmosphere of New Jersey

Abstract Concentrations of ten known or suspected toxic and/or carcinogenic volatile organic compounds, including benzene, chloroform, carbon tetrachloride, trichloroethylene, tetraehloroethylene, ortho‐ and para‐diehlorobenzene, 1,2‐dichloroethane, 1,1,1‐trichloroethane, and nitrobenzene were measured in ambient air. Samples were taken in three sections of northeastern New Jersey for purposes of discerning whether high concentrations of these species existed in selected areas of the state. The pollutants were collected by trapping on porous polymer (Tenax), thermal desorption, and high resolution gas chromatographic analysis. Concentrations in the low and sub‐part‐per billion range were found. Differences in the concentration levels of these pollutants were detectable when urban, suburban residential, and industrial areas were compared. The results obtained in this work prove to be comparable with those of researchers in other locations.

Speciation, preconcentration and determination of lead in natural water using chelating resin and direct GFAAS

Abstract A method has been developed for determination of trace metals in natural waters at the sub ppb level using sorption under static conditions on fine chelating resin beads. The metal can be quickly eluted from loaded beads with acid for GFAAS analysis, or the beads can be slurried in acid solution for direct GFAAS measurement. The method was applied to natural fresh water samples and lead was detected at levels down to 0.1 μg/L. The method distinguishes between lead in stable complexes and free lead ion. It permits preconcentration of trace metals from water in the field, thus avoiding the need to transport bulky water samples to the laboratory, and prevents the possibility of species inter-converting during storage and transportation. The sample-loaded beads can be stored before analysis with no apparent change in results.

Analysis of selected volatile organic compounds associated with residential kerosene heater use

Volatile organic species, including aliphatic hydrocarbons from hexane through dodecane, cyclohexane and the aromatic species benzene, toluene, ethyl benzene, nitrobenzene, ortho‐, meta‐, paraxylenes, styrene and naphthalene, associated with residential kerosene heater emissions, were measured at two sites: a small campus room (at NJIT) and living/dining room in a residence in Elizabeth, NJ. The analytical procedure involved collection of a series of air samples in stainless steel cartridges containing the porous polymer adsorbent, Tenax. The samples were recovered by thermal desorption, and analyzed by high resolution capillary column gas chromatography, employing a flame ionization detector. Mass spectral analysis was also used for qualitative identification of sample components. Moderately elevated levels of selected species (in 1–100 ppb range) were detected. Average pollutant level increases equivalent to 4.10 ppb and 7.35 ppb as hexane, were observed for NJIT and Elizabeth sites, respectively. The v...

Determination of selected toxic organic vapors in air by adsorbent trapping and capillary gas chromatography

Abstract Selected volatile organic species, including chloroform, 1,2‐dichloroethane, 1,1,1‐trichloroethane, benzene, carbon tetrachloride, trichloroethylene, tetrachloroethylene, p‐dichlorobenzene, o‐dichlorobenzene, and nitrobenzene, are determined in ambient air by collection and concentration on Tenax‐filled traps. The samples are recovered for analysis by a novel thermal desorption system which allows the injection of an aliquot of the sample into a 50M fused silica methyl silicone gas chromatographic column, which is programmed from ‐90 to 140° C. A standard addition process for qualitative analysis and an external standard method for quantitation are described, both using compressed gas standards. GC/MS is used for confirmation of sample identity on approximately 10% of the samples.

A study of the concentrations of selected organic vapors in the ambient atmosphere of suburban and rural New Jersey locations

Data were collected on a selected group of volatile organic compounds including aromatic, chlorinated aromatic, and halogenated one‐ and two‐carbon compounds at three sites in the state of New Jersey. Sampling took place at South Amboy, Rutherford and Batsto Village during 1979 and continued in 1980 at the latter two sites. Studies were also carried out on the correlation of the concentration data obtained with wind direction during sampling. The most frequently detected pollutants include the aromatic compounds, benzene, toluene, xylenes and chlorobenzene, as well as trichloroethylene and tetrachloroethylene. Concentration levels found were usually in the low part‐per‐billion range for Rutherford and South Amboy, with levels in Batsto averaging at least a factor of three lower. Correlation of wind direction with average concentration shows no significant trends for Rutherford or Batsto, but does indicate a general effect of industrial area pollution on South Amboy.