33
COMPARISON OF PARTICLE SIZE DISTRIBUTIONS FROM SIX TYPES OF AEROSOL SAMPLERS.
J. Park, J. Rock, C. Parnell, Texas A&M University, College Station, TX.
During the last century, knowledge about potential health effects of the exposure to particulate matter (PM) has grown. The health effects of PM depend on where they deposit in the respiratory tract and whether they are hydrophilic, corrosive, or reactive. Three particulate mass factions have been defined as inhalable, thoracic, and respirable with 50% cutoff at aerodynamic equivalent diameter of 100 µm, 10 µm, and 4 µm, respectively. These size conventions were co-developed and adopted by the International Organization for Standardization, the American Conference of Governmental Industrial Hygienists, and the Comité Européen de Normalisation in the early 1990s. This paper reports on a study of six types of aerosol samplers, evaluated experimentally with polydisperse fly ash. Three broad particle size distributions (PSDs) for inhalable, thoracic, and respirable were obtained by the Andersen and RespiCon samplers; a total suspended particulate (TSP) sample was quantified by particle volume using a Coulter Counter Multisizer (CCM). Fly ash samples were imaged with an environmental scanning electron microscope. Two Andersen, two RespiCon, four TSP, and four PM10 samplers were used to estimate airborne dust fractions. Two DustTraks and two SidePaks were used to monitor real time aerosol concentration. The results show that the Andersen, PM10, and TSP/CCM samplers provided comparable concentrations. There is good correlation (R2 = 0.9, 0.97, and 0.81) between Andersen, RespiCon, and TSP samplers for the PSDs of respirable, thoracic, and inhalable in the chamber study.
34
A COMPARATIVE ANALYSIS OF PERFORMANCE OF AEROSOL SAMPLERS UNDER FIELD CONDITIONS
FOR CAPTURING RESPIRABLE AND THORACIC DUST.
K. Hopp, S. Erdal, L. Brown-Ellington, T. Schoonover, L. Conroy, University of Illinois at Chicago, Chicago, IL.
The research focuses on characterizing aerosol sampler performance in two exposure environments, a woodshop and an industrial welding facility. A comparative analysis of the thoracic and respirable fractions is performed to gain insight into worker exposures in these industries, and an attempt is made to identify the most appropriate exposure assessment tool(s) to measure worker exposure. At the woodshop, area samples were collected at a fixed site. At the welding facility, air samples were collected at four stations across the facility. The Marple cascade impactor (CI) was used as the reference sampler in both locations due to the ability to construct particle size distributions, and to use the distribution to calculate concentrations in each of the three fractions, along with total dust concentrations. An IOM sampler was utilized at both locations to measure the inhalable fraction; the respirable fraction was measured with a personal exposure monitor (PEM2.5) at the welding facility but a PEM10 was used at the woodshop. A 37-mm open-face cassette measured total dust at both locations. The data indicates that the particle size distribution is normally distributed at the woodshop and log-normally distributed at the welding facility; the standard deviations and means will be discussed further with focus on the change in both of these variables spatially. In both data sets, the CI performed differently then the single stage samplers. In both settings, the IOM concentrations trended higher than the CI. The PEM2.5 and PEM10 concentration estimates were higher than the CI. The differences in concentration estimates between samplers were affected by the total concentrations in the environment, with higher concentrations creating higher discrepancies. Samplers used in this study are used extensively in both the field and research; the understanding of the performance of these samplers in different environments is an important subject needing further investigation.
35
FIELD INFRARED DETECTION ENHANCED WITH SOLID PHASE CONCENTRATION.
C. Bryant, Uniformed Services University of the Health Sciences, Bethesda, MD.
First responders and industrial hygienists are sometimes confronted with having to identify unknown substances in the field. Attenuated Total Reflection (ATR) Fourier Transform Infrared spectrometers can identify a wide range of unknown chemicals in liquid, powder, gel, and solid forms. Recent ATR designs have become lightweight and rugged, making them appealing for use in the field. The major shortcoming of an ATR instrument is that samples must have high concentrations of contaminant that must remain in contact with the diamond interface. ATR instruments currently cannot detect contaminants in water at concentrations less than 10% and they cannot detect chemicals in air. Solid-phase extraction media are known to concentrate chemicals from air or water by as much as eight orders of magnitude. In this research, common sorbent media and solid-phase extraction technologies are used to concentrate various chemicals from air and water. The performance of the various media on the portable HazMatID, manufactured by Smith’s Detection, are compared against each other. Using media capable of concentrating a chemical of interest will expand the capability of ATR technology in detecting chemicals found in trace concentrations in the environment.
36
COMPARISON OF NEW MERCURY VAPOR ANALYZER PERFORMANCE.
W. Raisanen, Reliable Instruments LLC, Washington, PA.
This report summarizes the results of comparative testing of a Jerome 431X and four prototypes of Reliable Instruments’ MVA-1 mercury analyzer. All units were challenged with mercury vapor concentrations ranging from 0.02 to 2.1 mg/M3.
All of the MVA-1 units tested were generally capable of meeting the accuracy specification of +/- 5%. Two exceptions are noted. Unit 10 was 6.67% low at the lowest concentration tested, and Unit 17 was 6.65% low at the 0.210 mg/m3 concentration. All other tests were within specification.
The Jerome instrument was 10 to 17% low at the lower levels, and within specification at the higher levels.
Low readings are typically produced at the end of the dynamic capacity of the gold film sensor used in both instrument designs. Regeneration of the sensor restores full accuracy. Each instrument was regenerated as needed during the testing.
The Reliable Instruments’ MVA-1 is substantially more repeatable than the Jerome 431X as indicated by the much smaller coefficient of variation values for the MVA-1.
37
USE OF PORTABLE X-RAY FLUORESCENCE (PXRF) IN MONITORING ARSENIC EXPOSURE DURING
THE PREVENTIVE MAINTENANCE TASK IN THE MICROELECTRONIC INDUSTRY.
Y. Hwang, W. Chu, National Taiwan University, Taipei, Taiwan Republic of China; T. Shi, D. Taung, Y. Hsiou, C. Chen, Institute of Occupational Safety and Health, Taipei, Taiwan Republic of China.
With the advantages of convenience and time-saving, the portable X-ray fluorescence (PXRF) is one of the best choices for arsenic monitoring in the relevant workplaces, such as preventative maintenance work in the semiconductor industry. The focus of the present study was thus set to evaluate the efficacy of PXRF use in the monitoring of arsenic exposure in workplace. Toyo Advantec 1 90-mm disc filter was selected for wipe sampling. In order to evaluate the validity of PXRF measurement for arsenic, standard arsenic/gallium mixed wipe samples were prepared for examination. Besides, 61 field wipe samples were collected from the workplace of a gallium arsenide wafer plant. All the standard and field wipe samples were analyzed in order with PXRF and inductively coupled plasma mass spectrometry (ICP-MS). Results show the arsenic measurement by PXRF was overestimated below the arsenic level around 25 ug/sample, and was underestimated for higher arsenic levels. The detection limit and quantitation limit for the PXRF arsenic measurement were 4.83 and 16.1 ug/sample, respectively, while the variation coefficients were at the well accepted level of less than 5% for arsenic contents greater than 50 ug/sample. Arsenic contents in all types of field samples ranged widely from 2.5 to 57,000 ug/sample. High correlation was observed between PXRF’s and ICP-MS’s arsenic measurements, r = 0.982 (p < 0.0001). Based on the correction equation, most of the arsenic contents in field samples could be estimated by the adjusted PXRF measurements with relative error less than 10%. It was concluded that the PXRF measurement for arsenic might be biased due to the interference from the existence of confounding element(s) and the width limitation of detection windows. Nevertheless, close estimate for arsenic exposure with PXRF measurement is possible for arsenic contents ranging from 16.1 up to 57,000 ug/sample.
38
FEASIBILITY STUDY FOR THE CLOSED CASSETTE EXTRACTION OF IOM SAMPLE CASSETTES.
C. Herrman, Broadspire (NATLSCO Laboratory), Lake Zurich, IL.
Closed cassette extraction of IOM cassettes has not been feasible due to the current cassette design. Polypropylene well plates were custom designed for the closed cassette extraction of 25-mm IOM sample cassettes containing 17-Beta Estradiol as a test article. 25-mm polytetrafluoroethylene (PTFE) filters spiked with known amounts of 17-Beta Estradiol were placed within an IOM cassette bottom and cassette top. The assembled cassettes were placed into individual wells of the extraction plate. 17-Beta Estradiol samples and matrix blank samples were extracted by pipetting 2 mL of solvent into each well containing an IOM cassette. Counter-sinking lids were attached to each well plate sealing each well, thus preventing cross-contamination. The well plates were agitated via a horizontal shaking device for 30 minutes. A high performance liquid chromatography (HPLC) method was developed for the determination of 17-Beta Estradiol as a test article, with Ethinyl Estradiol used as an internal standard. Standard linearity, precision, accuracy, and specificity were evaluated to test the effectiveness of the extraction procedure and the HPLC method. The HPLC method was found to be linear over the range of 4 to 100 ng/mL and met both precision and accuracy requirements at all concentrations. Intra-run precision met validation requirements over a 66-hour period. 17-Beta Estradiol samples were prepared at mass levels of: 10, 80, and 100 ng. Over the three levels, the percent recovery of 17-Beta Estradiol ranged from 90.9 to 98.8%, with a relative standard deviation of 1.77%. Matrix sample blanks demonstrated no interference with the test analyte or the internal standard throughout the study. Extraction of 17-Beta Estradiol from 25-mm PTFE filters using closed cassette extraction of IOM cassettes proved to be accurate, precise, and specific over the studied range. The custom well plates met the requirements as a feasible technique for the closed cassette extraction of IOM cassettes.
39
WORKPLACE AND AMBIENT AIR MONITORING OF BENZENE AND 1,3-BUTADIENE USING
DIFFUSIVE SAMPLING AND AUTOMATIC THERMAL DESORPTION.
A. Sunesson, M. Sundgren, J. Levin, National Institute for Working Life, Umea, Sweden.
Diffusive (passive) sampling of hazardous substances in air has been recognized as an efficient method for personal exposure assessment in occupational hygiene. In recent years diffusive sampling has also been increasingly utilized in ambient air quality studies, mainly in the form of stationary sampling and to some extent for personal monitoring in the general population. Diffusive samplers offer advantages: they are simple and convenient to use (and re-use), inexpensive, well characterized, appropriate for range of analytes, user-friendly, and can be operated by inexperienced personnel. There are disadvantages: it is important to ensure adequate air movement, they are not suitable for particulates, and sampling (uptake) rates are not always available. The simplicity of use makes the diffusive samplers suitable for personal exposure measurements. Workplace air monitoring is typically done with sampling times of 30 min to eight hours. For comparison with ambient air quality norms, prolonged sampling times, typically 1–4 weeks, are needed. We have validated the Perkin Elmer ATD diffusive sampler with Carbopack X adsorbent for sampling of benzene and 1,3-butadiene with sampling times from 30 min to one week. The Perkin-Elmer sampler with Carbopack X adsorbent is thermally desorbed in an automatic system, and benzene and 1,3-butadiene determined by gas chromatography-mass spectrometry. Uptake rates were determined in laboratory experiments using standard atmospheres and/or field comparisons with reference methods.
The following uptake rates were obtained:
40
DETERMINATION OF THE SAMPLING RATE VARIATION FOR ASSAY TECHNOLOGY CHEMDISK 571
ALDEHYDE MONITORS, SKC UMEX 100 PASSIVE SAMPLERS, AND SUPELCO DSD-DNPH PASSIVE
SAMPLERS.
M. Eide, U.S. DOL/OSHA Salt Lake Technical Center, Sandy, UT.
The sampling rate variation (SRV) has been established by OSHA as a measure of sampling rate error for diffusive samplers. SRV is the diffusive sampler equivalent of the often cited ± 5% sampling pump error used for active samplers. It is a unique number that is experimentally determined for each individual design of diffusive sampler because the SRV is presumed to be a function of sampler design. SRV provides the sampling error component of the sampling and analytical error calculations, which determine the uncertainty of an analytical result. SRV has been defined as the pooled relative standard deviation of sampling rates obtained in a modified version of the 16-run factor test described in the NIOSH testing protocol for diffusive samplers. The test requires sample collection from 16 different combinations of high and low analyte concentration, short and long sampling time, high and low face velocity, high and low relative humidity, and parallel and perpendicular sampler orientation to air flow direction in a sampling chamber. The Assay Technology ChemDisk 571 aldehyde monitors, SKC UMEx 100 passive samplers, and the Supelco DSD-DNPH Passive Samplers are intended by the manufacturer for use to measure the amount of formaldehyde and other aldehydes present in workplace air. The sampler uses 2,4-dinitrophenyl hydrazine (DNPH) chemistry to produce a stable aldehyde derivative. The SRV determination was based on the diffusive sampling rates of test atmospheres containing five different aldehydes: acetaldehyde, benzaldehyde, butyraldehyde, formaldehyde, and glutaraldehyde.
41
DIFFUSION BADGES AS A LONG-TERM, LOW-LEVEL METHOD OF AMBIENT AIR ANALYSIS.
K. Parker, Nova Research Inc., Alexandria, VA; S. Rose-Pehrsson, D. Kidwell, Naval Research Laboratory, Washington, DC.
Passive diffusion badges are being tested as a long-term, low-level method of analyte-specific air analysis onboard U.S. Navy nuclear submarines. Continuous atmosphere monitoring for potentially hazardous compounds is necessary for the protection of personnel living and working in closed space environments. Passive badge monitors, however, are only validated for a typical eight-hour working environment exposure. Long-term sampling efficiency is evaluated for a 28-day period by comparing the response of the passive badge to an active tube sampling method. Simultaneous exposure of badges and tubes occurs within a test chamber designed to provide a homogeneous gas sample. The badge exposure reflects a concentration level relevant to U.S. Navy 90-day submarine-specific limits. The samples are analyzed by their respective OSHA or NIOSH analytical methods, which include the use of HPLC, GC, GCMS, and UV spectroscopy. Formaldehyde, nitrogen dioxide, monoethanolamine, ozone, acrolein, and VOCs are among the various compounds of interest. As the badges are analyte-specific, a different chemistry is encountered with each compound. Preliminary analysis of formaldehyde demonstrated that badge and tube results may diverge over time. Although badges continued to accumulate analyte for 28 days, a non-linear trend was observed that may indicate saturation or an unstable derivative of the analyte. Analysis of NO2, however, did not show a decrease with time. Analyses of other gas analytes are currently underway. It is expected that accumulation may vary with each analyte in a way that is predictable, once the response characteristics of each analyte are established. With the relationships of accumulation known, passive diffusion badges may provide long-term, quantitative air monitoring.
42
PASSIVE VAPOR SAMPLING AND CONCENTRATION MODELING: SAMPLER AND METHOD
DEVELOPMENT.
J. Hodny, H. Anderson, II, W. L. Gore & Associates Inc., Elkton, MD.
Passive vapor sampling is used routinely for site assessment to delineate the nature and extent of subsurface impact by organic compounds as seen in the soil gas. Further, passive vapor sampling can be conducted to evaluate the presence of organic compounds in indoor and outdoor air. This approach usually employs a sorbent media which captures the compounds over a period of time. Compared to alternative active vapor sampling methods, passive sampling is simpler, more sensitive, and can analyze for a broad range of compounds at parts per trillion concentrations.
One available passive sampler combines engineered sorbents housed in a vapor permeable, chemically-inert, waterproof membrane. The membrane allows unimpeded vapor migration of organic compounds to the sorbent, while protecting the sample integrity. Traditionally, this method of passive vapor sampling provided quantitative mass-based results adequate to identify the kinds of compounds present, and spatially locate the extent of subsurface contamination. New techniques are now available to extend this technology by calculating vapor concentrations in air and in soil gas. Therefore, a more direct and comprehensive determination of health concerns are achieved when performing risk-based calculations that require vapor data in units of concentration.
The presentation includes a description of the sampler and the methods developed to report the vapor concentration data. Side-by-side passive and active vapor sampling events are compared for both indoor air and soil gas data. In this initial development effort, the comparison between the active and passive sampling data is quite good in general. The capability for reporting concentration data in vapor is demonstrated and can be used by the environmental professional to assess health risks.
43
DETERMINATION OF HEXAMETHYLENETETRAMINE IN AIR AND OFF-GAS EMISSIONS FROM
INDUSTRIAL PROCESSES.
C. Chan, CASSEN Testing Labs, Toronto, ON, Canada; D. Leong, Ontario Ministry of Labour, Toronto, ON, Canada.
Hexamethylenetetramine (HMTA) is widely used in many industrial applications and its demand has increased over the years. The currently revised Ontario Occupational Exposure Limits lists a STEL value of 0.35 ppm or 2 mg/m3 for this compound, however, there was no available validated method for its determination. Recent concern about health effects such as skin, eyes, mucous membranes, and upper respiratory tract irritation has led to the development of a method to measure HMTA in workplaces.
This paper describes a sampling and analytical method for the determination of HMTA in workplaces. Systematic evaluations of the method including precision, accuracy, recovery, MDL, background interferences, storage and stability studies, etc., have been undertaken. Field evaluation studies were also conducted to test the applicability of this method in industrial environments. In addition, other organic emissions from the manufacturing processes were identified to give complete profiles of VOCs using thermal desorption gas chromatography/mass spectrometry technique, which assisted in the determination of overall occupational exposure to airborne organics. The results demonstrate a rugged, reliable, and versatile method for the sampling and analysis of HMTA, as well as other organic emissions.
44
A SIMPLER, MORE COST-EFFECTIVE APPROACH FOR PERFORMING OSHA METHOD PV2120
COMPLIANT CANISTER SAMPLING.
D. Cardin, C. Casteel, T. Robinson, Entech Instruments Inc., Simi Valley, CA.
Small silonite-coated canisters are used to perform OSHA Method PV2120 for determination of a wide range of volatile chemicals in indoor air. These canisters have numerous advantages over other air sampling methods in that they do not physically change the sample in the field as do tubes and cartridges. Rather than performing the chemical separation in the field, the entire sample is collected with subsequent separation and analysis being performed in the laboratory under more controlled conditions. A drawback for this technique has been the initial cost of the canisters and field samplers used to fill the canisters. A new “valveless” canister has been developed that reduces the cost of the canisters and associated samplers, which in turn results in lower cost for analysis. Grab sampling, or virtually instant filling of the evacuated canister, is performed by simply removing and then replacing a vacuum-sealing plug. A septum in the plug allows a needle orifice to be used for time-weighted sampling. The internal o-ring seal is very inexpensive, allowing replacement prior to sampling to reduce the possibility for cross-contamination between sampling events. Performance of this new design compared to traditional valve-based canisters will be evaluated and presented, including compound recovery and practical considerations important to the sampling professional.
Posted May 30, 2005