A Syringe and Cartridge Method for Down-Hole Sampling for Trace Organics in Ground Water

A newly developed technique which allows the down-hole sampling and subsequent analysis of ground water for trace organic contaminants was tested during an investigation of contaminant migration at an inactive landfill site in Burlington, Ontario, Canada. The sampling device, which is lowered down piezometers with a tube, consists of a small cylindrical cartridge of sorbent material attached to a syringe. Vacuum or pressure applied at the surface controls the movement of the plunger in the syringe. The volume of the syringe determines the volume of sample water that passes through the cartridge. The cartridge is removed from the syringe at the surface. One cartridge is used for each sampling; the syringe is reusable. The residual water in the cartridge is removed in the laboratory, and the cartridge is desorbed to a fused silica capillary column for analysis by gas chromatography (GC). The analyses discussed here were performed on a GC/mass spectrometer/data system (GC/MS/DS). Of the many organic compounds that were identified in the samples, three compounds were clearly landfill-related: 1,1,1-trichloroethane, chlorobenzene, and para-dichlorobenzene. The three compounds were found at levels substantially above blank levels in 9, 5, and 5 piezometers, respectively. The average concentrations were 14., 5.3, and 0.88μg/1 (ppb), respectively. The pooled coefficients of variation for the analyses for the three compounds were 27., 6.9, and 6.4%, respectively. The volatility of 1,1,1-trichloroethane was probably the cause of the greater variability in its analytical data. The main advantages of the technique over most conventional sampling methods include: (1) down-hole sampling in a manner which minimizes the potential for volatilization losses; (2) avoidance of passage of the sample through long sections of tubing that may contaminate the sample or cause adsorptive losses; (3) convenience of sample handling, storage, and shipping; and (4) high sensitivity.     

The Effect of Air Bubbles and Headspace on the Aqueous Concentrations of Volatile Organic Compounds in Sampling Vials

The presence of headspace and air bubbles in volatile organic analysis sampling vials lowers the actual aqueous concentration of these compounds due to the partitioning of solutes into the gaseous phase. This could make the sample invalid for analysis.
In this work, the effects of air bubbles and headspace on the aqueous concentration of 60 volatile organic compounds listed in U.S.Environmental Protection Agency (U.S. EPA) Method 8260 were evaluated experimentally and theoretically. The results showed that for air to water ratios of 1 to 20 and less, there was no significant effect on the aqueous concentrations of target organic solutes in the sampling vials. When the air to water ratio was increased to 1 to 10, the recovery rates of four organic compounds were lower than the control. Laboratory experiments on sampling vials showed that the presence of air bubbles or headspace with the volumetric air to water ratios of 1 to 20 and less do not produce any significant effect on the original concentrations for most targeted volatile organic compounds.
The experimental results also indicated that in 40 mL sampling vials with headspace range of 2 to 8 mL, the recovery rates of most volatile organic compounds with high values of Henry's law constant (> 0.01 Atm m³/mol. at 25°C) were larger than the calculated rates.     

Evaluation of a Carbon Adsorption Method for Sampling Gasoline Vapors in the Subsurface

Monitoring of the vapor phase has emerged as a very convenient method for detecting volatile organic contaminants in the subsurface. It can provide a reliable way of placing ground water monitoring and recovery wells. The most common method uses a driveable ground probe (DGP) to extract a vapor-phase sample followed by direct injection of the vapor into a portable gas chromatograph (GC). However, many regional offices of regulatory agencies and consultants do not have ready access to such equipment. This research explores an alternative–the carbon adsorption method—in which the vapor is withdrawn by the DGP but concentrated on a small activated carbon trap (150mg). The carbon traps can be returned to a central laboratory for solvent extraction and GC analysis. This provides the advantages of increased sensitivity, reduction in field equipment and convenience of in-lab analyses (multiple GC injections are possible). A simple DGP and carbon trap system was constructed and tested at a field site. Vapor-phase concentrations of target compounds present in gasoline were mapped quite conveniently, ranging from 10,000μg/liter (vapor phase) to less than 10μg/L. These concentrations were also shown to decrease in the direction of the ground surface, as expected. Measurements of target compounds in soil showed that the vapor phase contributed a large fraction of the total contaminant burden where a non-aqueous-phase layer (NAPL) had been identified; as important, however, is the rather uniform contamination of the soil outside the NAPL region. Finally, the concentrations of target compounds in the vapor phase and ground water could be related in a manner roughly described by a simple equilibrium model, although exceptions were noted.     

Macro- and Micro-Purge Soil-Gas Sampling Methods for the Collection of Contaminant Vapors

Purging influence on soil‐gas concentrations for volatile organic compounds (VOCs), as affected by sampling tube inner diameter and sampling depth (i.e., system volume) for temporary probes in fine‐grained soils, was evaluated at three different field sites. A macro‐purge sampling system consisted of a standard, hollow, 3.2‐cm outer diameter (OD) drive probe with a retractable sampling point attached to an appropriate length of 0.48‐cm inner diameter (ID) Teflon^® tubing. The macro‐purge sampling system had a purge system volume of 24.5 mL at a 1‐m depth. In contrast, the micro‐purge sampling systems were slightly different between the field sites and consisted of a 1.27‐cm OD drive rod with a 0.10‐cm ID stainless steel tube or a 3.2‐cm OD drive rod with a 0.0254‐cm inner diameter stainless steel tubing resulting in purge system volumes of 1.2 and 7.05 mL at 1‐m depths, respectively. At each site and location within the site, with a few exceptions, the same contaminants were identified in the same relative order of abundances indicating the sampling of the same general soil atmosphere. However, marked differences in VOC concentrations were identified between the sampling systems, with micro‐purge samples having up to 27 times greater concentrations than their corresponding macro‐purge samples. The higher concentrations are the result of a minimal disturbance of the ambient soil atmosphere during purging. The minimal soil‐gas atmospheric disturbance of the micro‐purge sampling system allowed for the collection of a sample that is more representative of the soil atmosphere surrounding the sampling point. That is, a sample that does not contain an atmosphere that has migrated from distance through the geologic material or from the surface in response to the vacuum induced during purging soil‐gas concentrations. It is thus recommended that when soil‐gas sampling is conducted using temporary probes in fine‐grained soils, the sampling system use the smallest practical ID soil‐gas tubing and minimize purge volume to obtain the soil‐gas sample with minimal risk of leakage so that proper decisions, based on more representative soil‐gas concentrations, about the site can be made.     

Phytoscreening: A Comparison of In Planta Portable GC‐MS and In Vitro Analyses

Phytoscreening has been proven to rapidly delineate subsurface contaminant plumes for semiquantitative site assessment, with minimal impact to property or ecology through the collection and analysis of tree cores. Here, three phytoscreening methods were applied concurrently to identify multiple chlorinated volatile organic compounds (cVOCs) in a phytoremediation treatment system at a contaminated industrial facility. Tree coring, in planta gas chromatography–mass spectrometry (GC‐MS), and in planta passive sampling showed general agreement, with the in planta GC‐MS providing the quickest but least quantitative results. The portable GC‐MS sampling and analysis method identified six cVOCs in the xylem of hybrid poplars (Populus sp.) in the phytoremediation plot. These real‐time data can permit onsite identification and delineation of the contaminants, allowing for adaptive sampling during a single mobilization to a site. The in vitro methods provided quantitative data across two sampling campaigns, as relative cVOC concentrations remained similar between the two trips, despite a decrease in absolute cVOC concentrations from August to October. Overall, this research demonstrates the advantages and limitations of three phytoscreening techniques.     

Rapid Assessment of Trichloroethylene in Ground Water

On-site analysis of trichloroethylene (TCE) in aqueous samples by head- space sample preparation and gas chromatography (HS/GC) provides for quick and precise concentration estimates. This analytical approach is well suited for the on-site determination of volatile organic compounds (VOCs) in a variety of sample matrices, including ground water and saturated and unsatured soils. For these reasons, HS/GC can be used to establish analyte concentrations on a near real time basis to help select appropriate casing material during monitoring well installation. This application and the collection of multiple well samples during sampling events facilitates the hydrogeological site interpretation and the formulation of remediation strategies.     

Impact of Recharge Through Residual Oil Upon Sampling of Underlying Ground Water

At an aviation gasoline spill site in Traverse City, Michigan, historical records indicate a positive correlation between significant rainfall events and increased concentrations of slightly soluble organic compounds in the monitoring wells of the site. To investigate the recharge effect on ground water quality due to infiltrating, water percolating past residual oil and into the saturated zone, an in situ infiltration experiment was performed at the site. Sampling cones were set at various depths below a circular test area, 13 feet (4 meters) in diameter. Rainfall was simulated by sprinkling the test area at a rate sufficiently low to prevent runoff. The sampling cones for soil-gas and ground water quality were installed in the unsaturated and saturated zones to observe the effects of the recharge process. At the time of the test, the water table was below the residual oil layer. The responses of the soil-gas and ground water quality were monitored during the recharge and drainage periods, which resulted from the sprinkling.
Infiltrated water was determined to have transported organic constituents of the residual oil, specifically benzene, toluene, ethylbenzene, and ortho-xylene (BTEX), into the ground water beneath the water table, elevating the aqueous concentrations of these constituents in the saturated zone. Soil-gas concentrations of the organic compounds in the unsaturated zone increased with depth and time after the commencement of infiltration. Reaeration of the unconfined aquifer via the infiltrated water was observed. It is concluded that water quality measurements are directly coupled to recharge events for the sandy type of aquifer with an overlying oil phase, which was studied in this work. Ground water sampling strategies and data analysis need to reflect the effect of recharge from precipitation on shallow, unconfined aquifers where an oil phase may be present.     

A Diffusive Sampler for Passive Monitoring of Underground Storage Tanks

Passive measurements of volatile organic compounds (VOCs) provide a method for early detection and long-term monitoring of potential leaks from underground storage tanks (USTs) and associated fuel service lines. A diffusive sampler was constructed of a sorbent tube that fits inside a specially designed sampling chamber. VOCs in the soil enter the chamber by molecular diffusion and are collected by the sorbent. The sorbent is easily retrieved for laboratory analyses by thermally desorbing into a gas chromatograph/mass spectrometer (GC/MS), or qualitative concentrations can be determined directly in the field with specific-indicator detectors.
The diffusive samplers were evaluated in an exposure chamber under controlled conditions. Laboratory measurements of the sorbed mass of organic vapor were found to be in close agreement with theoretical values and indicate the passive sampling approach is viable for detecting relatively low concentrations of organic vapors in the vadose zone over a one-day sampling period, as well as providing relatively long-term monitoring periods up to 58 days. A field test found the sampling approach successful in identifying an area where the vadose zone was contaminated by leaking petroleum USTs.     

An Improved Gas Chromatographic Method for the Determination of C6–C12 Petroleum Hydrocarbons in Soil Water

In this work, investigations dealing with the determination of hydrocarbons in contaminated soil water are presented. The hydrocarbons under investigation range from low to high volatility compounds. A GC‐FID method was developed that due to its efficiency, routine suitability, relative rapidity, and low cost is suitable for the analysis of complex chemical mixtures of highly volatile hydrocarbons (with boiling points between 69 and 190°C). The standard used was a gasoline mixture with boiling points ranging from 100 to 190°C. For this standard, no supplementary preparation is needed and it is suitable for the whole range of hydrocarbons under investigation. The determination of the hydrocarbon content of the samples was performed applying univariate and multivariate statistical analysis to the experimental data. In the characterization of a contamination with highly volatile hydrocarbons of soil water originating from different depth layers from the chemistry location Leuna (Sachsen‐Anhalt, Germany), the advantages of a multivariate method are demonstrated in exemplary manner.     

A Method to Assess Analytical Uncertainties Over Large Concentration Ranges With Reference to Volatile Organics in Water

The uncertainty associated with a volatile organic concentration measurement is a function of variability and bias introduced at the various levels of sample handling: collection, storage, and analysis. During the past decade, sampling materials and the development and/or improvement of sampling protocols have been the subject of considerable research activity. As a result, in cases of samples properly handled, the analytical variability can be the dominant source of uncertainty in a given concentration value. Here analytical variability refers to any error that might arise during analysis, including the detector response error and any sample handling errors common to both standards and samples. This can be a particular concern for field analyses by gas chromatography (GC), Well-established statistical methods are available to estimate analytical uncertainty from linear calibration curves, but these methods are poorly suited for the analysis of volatile organics because organic samples frequently require instrument calibration (usually GC) over several orders of magnitude in concentration. If a single linear calibration curve is used to determine sample concentrations and uncertainties, then unrealistically large uncertainties may be assigned to low concentration samples. However, the methods can be adopted for extended concentration range calibration curves by breaking the overall calibration line down into smaller sub-calibration lines that span smaller ranges. These can then be examined and used selectively to determine concentrations with more appropriate uncertainties attached. The method of multiple callbration line analysis described here is suitable for programming with any high level computer language. It can be used to calculate meaningful analytical uncertainty values for any substance analyzed over a wide range in concentrations (i.e., an order of magnitude or more).     

Design, Installation, and Uses of Combination Ground Water and Gas Sampling Wells

Waste disposal sites with volatile organic compounds (VOCs) frequently contain contaminants that are present in both the ground water and vadose zone. Vertical sampling is useful where transport of VOCs in the vadose zone may effect ground water and where steep vertical gradients in chemical concentrations are anticipated. Designs for combination ground water and gas sampling wells place the tubing inside the casing with the sample port penetrating the casing for sampling. This physically interferes with pump or sampler placement. This paper describes a well design that combines a ground water well with gas sampling ports by attaching the gas sampling tubing and ports to the exterior of the casing. Placement of the tubing on the exterior of the casing allows exact definition of gas port depth, reduces physical interference between the various monitoring equipment, and allows simultaneous remediation and monitoring in a single well. The usefulness and versatility of this design was demonstrated at the Idaho National Engineering and Environmental Laboratory (INEEL) with the installation of seven wells with 53 gas ports, in a geologic formation consisting of deep basalt with sedimentary interbeds at depths from 7.2 to 178 m below land surface. The INEEL combination well design is easy to construct, install, and operate.     

Progressive Packer/Zone Sampling Method for VOC Plume Delineation in Consolidated Aquifers

The progressive packer/zone sampling method was used to identify the bottom of a plume of volatile organic compounds (VOCs) in the parts-per-million (ppm) range using one well in each of three separate locations. The method involves progressively drilling a 20-foot length of borehole through casing, setting an inflatable packer at the top of the drilled zone, purging the zone of three volumes of water using the airlift method, sampling the zone in situ through the packer string using a bailer, then repeating the procedure.
A plume consisting of chlorinated VOCs, alcohols, and vinyl chloride occurs in a low-yielding fractured bedrock aquifer located in the Passaic Formation at a site in central New Jersey. The thickness of the plume in total VOC concentrations exceeding 1 ppm was determined using the progressive packer/zone sampling method to a depth of 200 feet. The first borehole was completed as a monitoring well in the "hottest" zone encountered during testing. Additional wells were then clustered with this exploratory well to delineate the plume in the parts-per-billion (ppb) range. Cross contamination from previously sampled zones was not a problem as long as total VOCs in the ppm range were targeted and the sample interval was properly purged.
Instead of using a multiple well cluster consisting of an indefinite number of wells to determine the bulk thickness of a plume at a specific location, information from one borehole may suffice during the exploratory phase. Costs to the client and cross contamination potential to the aquifer can be minimized by limiting the number of boreholes needed for vertical delineation.     

Screening of Ground Water Samples for Volatile Organic Compounds Using a Portable Gas Chromatograph

A portable gas chromatograph was used to screen 32 ground water samples for volatile organic compounds. Seven screened samples were positive; four of the seven samples had volatile organic substances identified by second-column confirmation. Four of the seven positive, screened samples also tested positive in laboratory analyses of duplicate samples. No volatile organic compounds were detected in laboratory analyses of samples that headspace screening indicated to be negative. Samples that contained volatile organic compounds, as identified by laboratory analysis, and that contained a volatile organic compound present in a standard of selected compounds were correctly identified by using the portable gas chromatograph. Comparisons of screened-sample data with laboratory data indicate the ability to detect selected volatile organic compounds at concentrations of about 1 microgram per liter in the headspace of water samples by use of a portable gas chromatograph.     

Field Investigation of Vapor‐Phase‐Based Groundwater Monitoring

The use of in‐field analysis of vapor‐phase samples to provide real‐time volatile organic compound (VOC) concentrations in groundwater has the potential to streamline monitoring by simplifying the sample collection and analysis process. A field validation program was completed to (1) evaluate methods for collection of vapor samples from monitoring wells and (2) evaluate the accuracy and precision of field‐portable instruments for the analysis of vapor‐phase samples. The field program evaluated three vapor‐phase sample collection methods: (1) headspace samples from two locations within the well, (2) passive vapor diffusion (PVD) samplers placed at the screened interval of the well, and (3) field vapor headspace analysis of groundwater samples. Two types of instruments were tested: a field‐portable gas chromatograph (GC) and a photoionization detector (PID). Field GC analysis of PVD samples showed no bias and good correlation to laboratory analysis of groundwater collected by low‐flow sampling (slope = 0.96, R² = 0.85) and laboratory analysis of passive water diffusion bag samples from the well screen (slope = 1.03; R² = 0.96). Field GC analysis of well headspace samples, either from the upper portion of the well or at the water‐vapor interface, resulted in higher variability and much poorer correlation (consistently biased low) relative to laboratory analysis of groundwater samples collected by low‐flow sample or passive diffusion bags (PDBs) (slope = 0.69 to 0.76; R² = 0.60 to 0.64). These results indicate that field analysis of vapor‐phase samples can be used to obtain accurate measurements of VOC concentrations in groundwater. However, vapor samples collected from the well headspace were not in equilibrium with water collected from the well screen. Instead, PVD samplers placed in the screened interval represent the most promising approach for field‐based measurement of groundwater concentrations using vapor monitoring techniques and will be the focus of further field testing.     

The Sensitivity of Four Monitoring Well Sampling Systems to Low Concentrations of Three Volatile Organics

Four state-of-the-art ground water sampling systems were analyzed to determine their reliability in providing representative samples of the volatile chlorinated hydrocarbons trichloroethylene (TCE), perchloroethylene (PCE), and 1,1,1-trichloroethane (TCA) from a simulated monitoring well. The sampling systems studied represent four commonly used devices, including a stainless steel and Teflon® piston pump, a Teflon bailer, a Teflon bladder pump, and a PVC air-lift pump.
Controlled laboratory sampling experiments were conducted in a tank and well test chamber designed to approximate field conditions. A well purging and sampling procedure was used in the test apparatus to determine the accuracy and precision of each device for detecting low concentrations of the compounds in ground water. The compounds selected are some of the most ubiquitous hazardous contaminants found in shallow aquifers near hazardous waste sites throughout the United States.
No significant statistical difference was found among the four sampling systems in detecting the compounds.     

Observed Spatial and Temporal Distributions of CVOCs at Colorado and New York Vapor Intrusion Sites

The vapor intrusion impacts associated with the presence of chlorinated volatile organic contaminant plumes in the ground water beneath residential areas in Colorado and New York have been the subject of extensive site investigations and structure sampling efforts. Large data sets of ground water and indoor air monitoring data collected over a decade-long monitoring program at the Redfield, Colorado, site and monthly ground water and structure monitoring data collected over a 19-month period from structures in New York State are analyzed to illustrate the temporal and spatial distributions in the concentration of volatile organic compounds that one may encounter when evaluating the potential for exposures due to vapor intrusion. The analysis of these data demonstrates that although the areal extent of structures impacted by vapor intrusion mirrors the areal extent of chlorinated volatile organic compounds in the ground water, not all structures above the plume will be impacted. It also highlights the fact that measured concentrations of volatile organic compounds in the indoor air and subslab vapor can vary considerably from month to month and season to season. Sampling results from any one location at any given point in time cannot be expected to represent the range of conditions that may exist at neighboring locations or at other times. Recognition of this variability is important when designing sampling plans and risk management programs to address the vapor intrusion pathway.     

Comparison of Two Integrated Methods for the Collection and Analysis of Volatile Organic Compounds in Ground Water

The principal difficulties with determinations of volatile organic compounds (VOCs) in ground water are the reliability of sampling procedures and analytical methods. Two integrated methods have been developed for routine sampling, processing, and analysis of VOCs in ground water. These methods involve in situ collection of ground water using a modified syringe sampler from PVC piezometers or using dedicated glass syringes from stainless steel multilevel bores. The samples are processed in the syringe using purge and trap or microsolvent extraction and analyzed by GC/MSD.
The modified purge-and-trap method is time-consuming and limited to volatile organic compounds. However, it is extremely sensitive and flexible: the volume of sample used can be varied by the use of different-size glass syringes (sample volumes from 1 to 100 mL).
In cases where extremely low sensitivity (<10 mg 1⁻¹) is not critical, the microextraction technique is a more cost-effective method, allowing twice as many samples to be analyzed in the same time as the purge-and-trap method. It enables less volatile compounds such as polynuclear aromatic hydrocarbons, phenol, and cresols to be analyzed in the same GC run. Also, the microextraction method can be used in the field to avoid delays associated with transportation of ground water samples to the laboratory.     

Removal of Volatile Organic Compounds in Vertical Flow Filters: Predictions from Reactive Transport Modeling

Vertical flow filters are containers filled with porous medium that are recharged from top and drained at the bottom, and are operated at partly saturated conditions. They have recently been suggested as treatment technology for groundwater containing volatile organic compounds (VOCs). Numerical reactive transport simulations were performed to investigate the relevance of different filter operation modes on biodegradation and/or volatilization of the contaminants and to evaluate the potential limitation of such remediation mean due to volatile emissions. On the basis of the data from a pilot‐scale vertical flow filter intermittently fed with domestic waste water, model predictions on the system’s performance for the treatment of contaminated groundwater were derived. These simulations considered the transport and aerobic degradation of ammonium and two VOCs, benzene and methyl tertiary butyl ether (MTBE). In addition, the advective‐diffusive gas‐phase transport of volatile compounds as well as oxygen was simulated. Model predictions addressed the influence of depth and frequency of the intermittent groundwater injection, degradation rate kinetics, and the composition of the filter material. Simulation results show that for unfavorable operation conditions significant VOC emissions have to be considered and that operation modes limiting VOC emissions may limit aerobic biodegradation. However, a suitable combination of injection depth and composition of the filter material does facilitate high biodegradation rates while only little VOC emissions take place. Using such optimized operation modes would allow using vertical flow filter systems as remediation technology suitable for groundwater contaminated with volatile compounds.     

Evidence for Instantaneous Oxygen-Limited Biodegradation of Petroleum Hydrocarbon Vapors in the Subsurface

Petroleum hydrocarbon vapors biodegrade aerobically in the subsurface. Depth profiles of petroleum hydrocarbon vapor and oxygen concentrations from seven locations in sandy and clay soils across four states of Australia are summarized. The data are evaluated to support a simple model of biodegradation that can be used to assess hydrocarbon vapors migrating toward built environments. Multilevel samplers and probes that allow near‐continuous monitoring of oxygen and total volatile organic compounds (VOCs) were used to determine concentration depth profiles and changes over time. Collation of all data across all sites showed distinct separation of oxygen from hydrocarbon vapors, and that most oxygen and hydrocarbon concentration profiles were linear or near linear with depth. The low detection limit on the oxygen probe data and because it is an in situ measurement strengthened the case that little or no overlapping of oxygen and hydrocarbon vapor concentration profiles occurred, and that indeed oxygen and hydrocarbon vapors were largely only coincident near the location where they both decreased to zero. First‐order biodegradation rates determined from all depth profiles were generally lower than other published rates. With lower biodegradation rates, the overlapping of depth profiles might be expected, and yet such overlapping was not observed. A model of rapid (instantaneous) reaction of oxygen and hydrocarbon vapors compared to diffusive transport processes is shown to explain the important aspects of the 13 depth profiles. The model is simply based on the ratio of diffusion coefficients of oxygen and hydrocarbon vapors, the ratio of the maximum concentrations of oxygen and hydrocarbon vapors, the depth to the maximum hydrocarbon source concentration, and the stoichiometry coefficient. Whilst simple, the model offers the potential to incorporate aerobic biodegradation into an oxygen‐limited flux‐reduction approach for vapor intrusion assessments of petroleum hydrocarbon compounds.     

Laboratory Comparison of Polyethylene and Dialysis Membrane Diffusion Samplers

The ability of diffusion samplers constructed from regenerated cellulose dialysis membrane and low density, lay flat polyethylene tubing to collect volatile organic compounds and inorganic ions was compared in a laboratory study. Concentrations of vinyl chloride, cis -1, 2-dichloroethene, bromochloromethane, trichloroethene, bromodichloromethane, and tetrachloroethene collected by both types of diffusion samplers reached equilibrium with the concentrations of these compounds in test solution within three days. Concentrations of bromide and iron collected by the dialysis membrane diffusion samplers reached equilibrium with the concentrations of these compounds in a test solution within three to seven days. No detectable concentrations of bromide or iron were found in polyethylene diffusion samplers even after 21 days. No measurable concentrations of aluminum, arsenic, barium, cadmium, chromium, iron, mercury, manganese, nickel, and lead, or sulfide, were leached out of dialysis membrane samplers over seven days. Compared with using a gas-tight syringe to sample the diffusion sampler, clipping the bag and pouring the water sample into a sample vial resulted in only a small 6.2% average loss of volatile organic compounds. Dialysis membrane diffusion samplers offer promise for use in sampling ground water for inorganic constituents as well as volatile organic compounds.