Michael J. Brisson

Interlaboratory Evaluation of a Portable Fluorescence Method for the Measurement of Trace Beryllium in the Workplace

Researchers at Los Alamos National Laboratory (LANL) developed a field-portable fluorescence method for the measurement of trace beryllium in workplace samples such as surface dust and air filters. The technology has been privately licensed and is commercially available. In cooperation with the Analytical Subcommittee of the Beryllium Health and Safety Committee, we have carried out a collaborative interlaboratory evaluation of the LANL field-portable fluorescence method. The interlaboratory study was conducted for the purpose of providing performance data that can be used to support standard methods. Mixed cellulose ester (MCE) membrane filters and Whatman 541 filters were spiked with beryllium standard solutions so that the filters spanned the range ≈0.05 - ≈0.5 µg Be per sample. Sets of these filters were then coded (to ensure blind analysis) and sent to participating laboratories, where they were analyzed. Analysis consisted of the following steps: 1. Removal of the filters from transport cassettes and placement of them into 15-mL centrifuge tubes; 2. mechanically- assisted extraction of the filters in 5 mL of 1 % ammonium bifluoride solution (aqueous) for 30 min; 3.-4. filtration and transfer of sample extract aliquots (100 µL) into fluorescence cuvettes; 5. introduction of 1.9 mL of detection solution (to effect reaction of the fluorescence reagent with beryllium in the extracted sample); and 6. measurement of fluorescence at ≈475 nm using a portable fluorometer. This work presents performance data in support of a procedure that is targeted for publication as a National Institute for Occupational Safety and Health (NIOSH) method and as an ASTM International standard.

Analytical Performance Criteria: Standardized Surface Dust Sampling Methods for Metals, with Emphasis on Beryllium

This article was prepared by U.S. government employees as part of their official duties and legally may not be copyrighted in the United States of America. Mention of company names or products does not constitute endorsement by the Centers for Disease Control and Prevention, the U.S. Departments of Defense and Energy, or their contractors. The contents and conclusions of this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health. INTRODUCTION

Interlaboratory Evaluation of a Standardized Inductively Coupled Plasma Mass Spectrometry Method for the Determination of Trace Beryllium in Air Filter Samples

A collaborative interlaboratory evaluation of a newly standardized inductively coupled plasma mass spectrometry (ICP-MS) method for determining trace beryllium in workplace air samples was carried out toward fulfillment of method validation requirements for ASTM International voluntary consensus standard test methods. The interlaboratory study (ILS) was performed in accordance with an applicable ASTM International standard practice, ASTM E691, which describes statistical procedures for investigating interlaboratory precision. Uncertainty was also estimated in accordance with ASTM D7440, which applies the International Organization for Standardization Guide to the Expression of Uncertainty in Measurement to air quality measurements. Performance evaluation materials (PEMs) used consisted of 37 mm diameter mixed cellulose ester filters that were spiked with beryllium at levels of 0.025 (low loading), 0.5 (medium loading), and 10 (high loading) μ g Be/filter; these spiked filters were prepared by a contract laboratory. Participating laboratories were recruited from a pool of over 50 invitees; ultimately, 20 laboratories from Europe, North America, and Asia submitted ILS results. Triplicates of each PEM (blanks plus the three different loading levels) were conveyed to each volunteer laboratory, along with a copy of the draft standard test method that each participant was asked to follow; spiking levels were unknown to the participants. The laboratories were requested to prepare the PEMs by one of three sample preparation procedures (hotplate or microwave digestion or hotblock extraction) that were described in the draft standard. Participants were then asked to analyze aliquots of the prepared samples by ICP-MS and to report their data in units of μ g Be/filter sample. Interlaboratory precision estimates from participating laboratories, computed in accordance with ASTM E691, were 0.165, 0.108, and 0.151 (relative standard deviation) for the PEMs spiked at 0.025, 0.5, and 10 μ g Be/filter, respectively. Overall recoveries were 93.2%, 102%, and 80.6% for the low, medium, and high beryllium loadings, respectively. Expanded uncertainty estimates for interlaboratory analysis of low, medium, and high beryllium loadings, calculated in accordance with ASTM D7440, were 18.8%, 19.8%, and 24.4%, respectively. These figures of merit support promulgation of the analytical procedure as an ASTM International standard test method, ASTM D7439.

The Real Issue with Wall Deposits in Closed Filter Cassettes—What's the Sample?

The measurement of aerosol dusts has long been utilized to assess the exposure of workers to metals. Tools used to sample and measure aerosol dusts have gone through many transitions over the past century. In particular, there have been several different techniques used to sample for beryllium, not all of which might be expected to produce the same result. Today, beryllium samples are generally collected using filters housed in holders of several different designs, some of which are expected to produce a sample that mimics the human capacity for dust inhalation. The presence of dust on the interior walls of cassettes used to hold filters during metals sampling has been discussed in the literature for a number of metals, including beryllium, with widely varying data. It appears that even in the best designs, particulates can enter the sampling cassette and deposit on the interior walls rather than on the sampling medium. The causes are not well understood but are believed to include particle bounce, electrostatic forces, particle size, particle density, and airflow turbulence. Historically, the filter catch has been considered to be the sample, but the presence of wall deposits, and the potential that the filter catch is not representative of the exposure to the worker, puts that historical position into question. This leads to a fundamental question: What is the sample? This article reviews the background behind the issue, poses the above-mentioned question, and discusses options and a possible path forward for addressing that question.

Opportunities for Standardization of Beryllium Sampling and Analysis

Since the U. S. Department of Energy (DOE) published the DOE Beryllium Rule (10 CFR 850) in 1999, DOE sites have been required to measure beryllium in air filter and surface wipe samples for purposes of worker protection and for release of materials from beryllium-controlled areas. Measurements in the nanogram range on a filter or wipe are typically required. Industrial hygiene laboratories have applied methods from various analytical compendia, and a number of issues have emerged concerning sampling and analysis practices. As a result, a committee of analytical chemists, industrial hygienists, and laboratory managers was formed in November 2003 to address the issues. The committee developed a baseline questionnaire and distributed it to DOE sites and other agencies in the U.S., Canada, and the U.K. The results of the questionnaire are presented in this paper. These results confirmed that a wide variety of practices was in use in the areas of sampling, sample preparation, and analysis. Additionally, although these laboratories are generally accredited by the American Industrial Hygiene Association (AIHA), there are inconsistencies in execution among accredited laboratories. As a result, there are significant opportunities for development of standard methods that could improve consistency. The current availabilities and needs for standard methods are further discussed in a companion paper.

Sampling and analysis issues relating to the ACGIH notice of intended change for the beryllium threshold limit value.

Column Editor Kevin AshleyBeryllium in various forms is widely used throughout the world in ceramics, aerospace and military applications, electronics, and sports equipment. Workplace exposure to beryllium is a growing industrial hygiene concern due to the potential for development of chronic beryllium disease (CBD), a lung condition with no known cure, in a small percentage of those exposed. There are workplace exposure limits for beryllium that have been in place for several decades. However, recent studies suggest that the current American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) and the Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) may not be sufficiently protective for workers who are potentially exposed to airborne beryllium. Early in 2005, ACGIH issued a Notice of Intended Change (NIC) to the current TLV for beryllium which entails a 100-fold reduction (from 2 to 0.02 micrograms per cubic meter of sampled air). It is noted that ACGIH TLVs do not carry legal force in the manner that OSHA PELs or other federal regulations do. Nevertheless, OSHA plans a beryllium rulemaking in the near future, and a reduction in the PEL is anticipated. Also, if this change in the TLV for beryllium is adopted, it is reasonable to assume that at least some sampling and analysis activities will need to be modified to address airborne beryllium at the lower levels. There are implications to both the industrial hygiene and the laboratory communities, which are discussed.

Interlaboratory evaluation of a standardized inductively coupled plasma-mass spectrometry method for the determination of trace elements in air filter samples: preliminary results

An interlaboratory evaluation of a standardized inductively coupled plasma-mass spectrometry (ICP-MS) method for determining trace elements in workplace air samples was carried out, toward fulfillment of method validation requirements for international voluntary consensus standard test methods. The interlaboratory study was performed in accordance with an applicable ASTM International standard practice, ASTM E691, which describes statistical procedures for investigating interlaboratory precision. Performance evaluation materials, prepared by a contract laboratory, consisted of mixed-cellulose ester filters that were spiked with 21 elements of interest at levels of 0.50 or 5.0 micrograms (µg) per filter. Triplicates of each spiked filter, plus media blanks spiked with blank reagent, were conveyed to each volunteer laboratory; spiking levels were unknown to the participants. The laboratories were requested to prepare the filter samples by one of the three sample preparation procedures (hotplate or microwave digestion or hotblock extraction) that are described in the standard test method, ASTM D7439. Participants were then asked to analyze aliquots of the prepared samples by ICP-MS using ASTM D7439, and to report their data in units of µg per filter sample. Preliminary interlaboratory precision and recovery estimates from 20 volunteer laboratories are reported.