RESUMEN
To assess worker isocyanate exposures in a variety of processes involving the manufacture and use of surface coatings, polyurethane foams, adhesives, resins, elastomers, binders, and sealants, it is important to be able to measure airborne reactive isocyanate-containing compounds. Choosing the correct methodology can be difficult. Isocyanate species, including monomers, prepolymers, oligomers, and polyisocyanates, are capable of producing irritation to the skin, eyes, mucous membranes, and respiratory tract. The most common adverse health effect is respiratory sensitization, and to a lesser extent dermal sensitization and hypersensitivity pneumonitis. Furthermore, isocyanate species formed during polyurethane production or thermal degradation may also produce adverse health effects. Isocyanate measurement is complicated by the fact that isocyanates may be in the form of vapors or aerosols of various particle size; the species of interest are reactive and therefore unstable; few pure analytical standards exist; and high analytical sensitivity is needed. There are numerous points in the sampling and analytical procedures at which errors can be introduced. The factors to be considered for selecting the most appropriate methodology for a given workplace include collection, derivatization, sample preparation, separation, identification, and quantification. This article discusses these factors in detail and presents a summary of method selection criteria based on the isocyanate species, its physical state, particle size, cure rate, and other factors.
Asunto(s)
Contaminantes Ocupacionales del Aire/análisis , Monitoreo del Ambiente/métodos , Isocianatos/análisis , Cromatografía de Gases/métodos , Humanos , Hipersensibilidad/etiología , Isocianatos/efectos adversos , Isocianatos/química , Concentración Máxima Admisible , National Institute for Occupational Safety and Health, U.S. , Estados UnidosRESUMEN
The NIOSH sampling and analytical method for inorganic acids employs a silica gel sorbent tube for the collection of five common inorganic acids with simultaneous determination of these acids in a single sample by ion chromatography. When the method was extended to the determination of hydrogen fluoride (HF) the sampled HF reacted with the silica gel and glass fiber of the sampler, but the reaction products remained trapped on the sorbent. Silica gel samplers were evaluated for the collection of HF from laboratory generated atmospheres. Factors tested included capacity, storage stability, humidity, accuracy and precision. Based on comparison with impinger collection, the mean recovery of HF from silica gel tube samples was 100.7% with a precision of 0.144.
Asunto(s)
Contaminantes Ocupacionales del Aire/análisis , Ácido Fluorhídrico/análisis , Dióxido de Silicio , Adsorción , Cromatografía por Intercambio Iónico , Estudios de Evaluación como Asunto , Humanos , Gel de Sílice , Estados Unidos , United States Occupational Safety and Health AdministrationRESUMEN
The following four commercial sulfur dioxide passive monitors were tested for performance and realiability: DuPont Pro-Tek C-20 air monitoring badges; MSA Vaporgard Dosimeter tubes; REAL BioBadges; and 3M Sulfur Dioxide Nutshell monitors. The experiments conducted were designed to test factors critical to the operation of passive samplers: accuracy and precision; capacity; stability; analytical recovery; and the effects of exposure time, concentration, humidity, face velocity, orientation, chemical interference, and temperature. The DuPont Pro-Tek badges performed satisfactorily for all the factors tested, and the REAL BioBadges performed satisfactorily except for the instability of the SO2/tetrachloromercurate complex when stored. An alternate monitoring system, REAL BioBadges containing deionized water absorbent had a limited capacity. Only the MSA dosimeters exhibited unsatisfactory performance. The 3M Nutshell monitor was withdrawn by the manufacturer after only partial evaluation.