Eugene R. Kennedy

A Sampling and Analytical Method for the Simultaneous Determination of Multiple Organophosphorus Pesticides in Air

A sampling and analytical method for organophosphorus pesticides using a combined filter/XAD-2 sorbent sampler and gas chromatography (GC)-flame photometric detection (FPD) was developed. The method was evaluated for 19 organophosphorus pesticides based on the joint Occupational Safety and Health Administration/National Institute for Occupational Safety and Health Standards Completion Program methods evaluation protocol. The evaluation addressed analyte recovery, sampler capacity, sample stability, and precision and accuracy. Additional experiments addressed long-term sample stability (30-day storage), short-term exposure limits, limits of detection, and concentration levels down to 0.1 times an exposure limit value. Samples were stable for 30 days of storage under either ambient or refrigerated conditions. Based on this research, all 19 compounds studied can be successfully determined simultaneously using one method with an accuracy of +/- 25% of the true value 95 times out of 100.

Evaluation of the Du Pont Pro-Tek® Formaldehyde Badge and the 3M Formaldehyde Monitor

The 3M Formaldehyde Monitor and the DuPont Pro-Tek Formaldehyde Badge were evaluated for performance and reliability. This evaluation revealed that the 3M monitor results were variable and lower than reference concentrations determined independently. When the monitors were humidified before use and then exposed in humid (ca. 80% RH) formaldehyde-containing atmosphere, the monitors did give accurate results. Results of additional experiments led to the conclusion that quantitative reaction between formaldehyde generated in our chamber and the absorbent pad in the 3M monitor required the presence of a minimum level of absorbed water. The DuPont badges gave good agreement with the reference concentrations determined independently under the following conditions: sampling period of 1 to 12 hr with a minimum integrated sample loading of 4 ppm-hr; at least 3 m/min (10 ft/min) face velocity; correction for blank badges; and correction for loss of reagent from the samples. The evaluation indicated that the DuPont badge was not well suited to short term sampling and was subject to evaporation of liquid from the absorbing liquid blister. Blank values also were found to be variable, necessitating the analysis of several blanks to be used for blank correction with each set of samples. This blank variability also contributed to high variability found when short term measurements were made. The badge also had a negative interference from phenol at high phenol-to-formaldehyde ratios. Some of the major problems observed with both passive monitors were found only after devices which had been aged under storage conditions were analyzed and these results interpreted. If all testing had been done with fresh sampling devices, many of the problems would not have been noticed. Based on the results of this study, this factor of diffusive monitor aging needs to be addressed in any further work on passive monitor evaluation.

Application of multidimensional gas chromatography—mass spectrometry to the determination of glycol ethers in air

The applicability of multidimensional gas chromatography-mass spectrometry to the analysis of five glycol ethers in air was demonstrated. Air samples were collected on charcoal tubes and desorbed with 5% methanol in methylene chloride as is described in method 1403 of the National Institute for Occupational Safety and Health Manual of Analytical Methods. The glycol ethers were determined by multidimensional gas chromatography-mass spectrometry. The limit of detection was 5 to 7 micrograms/sample for each compound.

Workplace monitoring for volatile organic compounds using thermal desorption-gas chromatography-mass spectrometry.

The interest in the identification of volatile organic compounds in the workplace has been a major focus of many National Institute for Occupational Safety and Health (NIOSH) field studies. A primary technique for sampling and analysis of these compounds is summarized by NIOSH Manual of Analytical Methods (NMAM) 2549. This is a screening method that uses a multi-bed sorbent to trap a wide variety of compounds and compound classes. Thermal desorption techniques are used as a first attempt to characterize potential contaminants in a workplace and to determine what future sampling and analyses must be performed. Field examples are provided to show the versatility of thermal desorption methods and techniques. Due to their sensitivity, thermal desorption tube methods are sometimes required in order to measure the workplace concentrations of unusual compounds. In other situations, the exposures are too high or varied to make thermal desorption tubes practical. In these cases, the identification of contaminants with thermal desorption tubes leads to new method developments for the quantification of specific compounds using more conventional solid sorbent-solvent desorption based methods.

Instability of Formaldehyde Air Samples Collected on a Solid Sorbent

In May, 1980, an article appeared in the American Industrial Hygiene Association Journal which described a new method for sampling and analysis of formaldehyde vapor in air. Recent experiments have shown that samples collected according to this method (currently designated as NIOSH P&CAM 318) are unstable. This paper describes some of these experiments and presents data which show that ambient temperatures and storage times in excess of one week contribute to sample loss.

The Determination in Air of Selected Low-Molecular Weight Aldehydes as Their Oxazolidines by Capillary Gas Chromatography

Abstract The sampling of 2-furaldehyde, pentanedial, and pentanal from air has been accomplished using sorbent tubes containing 120-mg and 60-mg beds of XAD-2 coated with 10 percent 2-(hydroxymethyl)piperidine. Samples were collected at ca. 50 cm3/min for a maximum of 4 hours for 2-furaldehyde, ca. 80 cm3/min for a maximum of 8 hours, or ca. 200 cm3/min for minimum of 15 minutes for pentanedial and ca. 40 cm3/min for a maximum of 4 hours for pentanal. The oxazolidines, formed by reaction of the 2-(hydroxymethyl)piperidine with the aldehydes, were desorbed from the sorbent with 2 ml of toluene. Recovery from the sorbent was essentially quantitative for the aldehydes, and the resulting solution was analyzed by gas chromatography using a fused-silica capillary DB-5 column. Typical limits of detection ranged from 0.2–0.6 μg/sample for 2-furaldehyde, pentanedial, and pentanal. Pooled relative standard deviations for sets of 18 samples were 7.6 percent (3–41 mg/m3) for 2-furaldehyde, 8.7 percent (1–8 mg/m3) for...

Summary of the NIOSH guidelines for air sampling and analytical method development and evaluation

Suggested guidelines for the development and evaluation of sampling and analytical methods for industrial hygiene monitoring have recently been published in a NIOSH technical report. These guidelines are based in part on various published approaches for method development and evaluation and serve as an attempt at a more unified experimental approach. This paper presents some salient features of this unified approach for method development and evaluation. The basic goal of the approach is to determine if the method under study meets the criterion to produce a result that fell within 25% of the true value 95 times out of 100 on average, although other factors of method performance are evaluated. The experiments proposed for the evaluation of method performance include determination of analytical recovery from the sampler, sampler capacity, storage stability of samples and effect of environmental factors. Evaluation criteria for the experimental data and procedures for the calculation of method bias, precision and accuracy are also included.

Fourier Transform Infrared Spectrometry/Attenuated Total Reflectance Study of the Reaction of Pentanal and Propanal with 2-(Hydroxymethyl)Piperidine:

The reactions of propanal and pentanal with 2-(hydroxymethyl)piperidine were investigated by Fourier transform infrared spectrometry/attenuated total reflectance in both the solution phase and at the gas/solid interface. The reactions were studied with the use of a flow-through cylindrical internal reflection (“circle”) cell. Reaction intermediates were tentatively identified by their characteristic infrared absorption frequencies. At the gas/solid interface the reaction is thought to yield a hemiaminal intermediate. In the solution phase a hemiaminal intermediate is believed to form initially, followed by loss of water to generate an enamine product. In both gas-phase and solution-phase studies, an oxazolidine product is prepared only after an ultrasound treatment. The FT-IR/ATR technique reveals detailed mechanistic information concerning reactions between aldehydes and ethanol amines.

Development and Evaluation of a Method to Estimate Potential Formaldehyde Dose from Inhalable Dust/Fibers

Abstract A method for the estimation of formaldehyde dose from inhalable dust/fibers using a commercially available inhalable sampler was developed. Filters containing sampled dust/fibers were placed in 10 ml of distilled water and incubated at 37°C for 4 hours to liberate the formaldehyde from the dust/fibers. After incubation, the filter extracts were passed with a 0.45 μm filter to remove particles left in the extracts. Two analytical procedures were used for the analysis of the filter extracts. Either a 4-ml aliquot was analyzed using the chromotropic acid procedure, as outlined in NIOSH Method 3500, or a 1-ml aliquot was treated with 2,4-dinitrophenylhydrazine and a catalytic amount of perchloric acid and analyzed by high-performance liquid chromatography for the resulting 2,4-dinitrophenylhydrazone. The limits of detection for the chromotropic acid procedure and the 2,4-dinitrophenylhydrazine procedure were 0.44 and 0.08 μg per filter sample, respectively. Relative standard deviations of replicate d...

A Computer Program to Promote Understanding of the Monitoring Method Evaluation Guidelines Used at NIOSH

A computer-based training program has been devised to promote better understanding of the recently revised National Institute for Occupational Safety and Health (NIOSH) test guidelines applicable to methods requiring on-site sample collection and laboratory sample analysis of airborne toxic substances. A statistics section explains the basis of the NIOSH accuracy criterion (NAC); an experiments section provides details on the evaluation experiments; and a calculations section calculates method statistics based on data entered by the user. The statistics section graphically explains concepts such as the NAC and limit of detection, allowing the user to experiment with some parameters to see how the results are affected. This section also provides background material to show how some of the performance criteria evolved. The experiments section provides a summary of the experiments used to generate the data for method evaluation. The calculations section has several screens that work like customized spreadsheets for the entry of data collected during the laboratory evaluation of a method. A separate screen then calculates the precision (relative standard deviation) of analytical results at each of four concentrations, tests to see if the precision values are statistically homogeneous, and combines the homogeneous data for calculation of the relative standard deviation. It does the same for bias, and combines the precision with method bias to arrive at an estimate of method accuracy. Other screens in the calculations section facilitate the determination of method limit of detection and sample storage stability.