title: Detection of organophosphate pesticides using a prototype liquid crystal monitor.
abstract: The precision and accuracy of a prototype wearable liquid crystal monitor (LCM) for the measurement of airborne organophosphate pesticide concentrations was explored in a series of laboratory experiments. LCM response to vapor-phase and aerosol diazinon was compared to concentrations obtained using a standard reference method (NIOSH 5600) at concentrations ranging from approximately 8 to 108 ppb (parts per billion) over durations of 2 to 80 hours. Temperature ( approximately 25, 30, and 35 degrees C) and relative humidity (15, 50, and 85%) were varied to estimate the effect of these factors on LCM performance. The LCM response to vapor phase pesticide exposure was linear for concentrations in the range of 8-20 ppb. At exposure concentrations above approximately 20 ppb, however, there was a decline in monitor response and measurement precision. Elevated temperatures improved diazinon vapor-only measurement precision, while increased relative humidity reduced LCM response at the extremes of tested temperatures. Compared to vapor-only exposures, the LCM was less sensitive to diazinon aerosol concentrations, but displayed reasonable precision over a relatively large range of exposures (29 to 1190 ppb-hr). Further efforts to characterize temperature and humidity effects and improve low-end sensitivity would likely provide a portable personal exposure monitor or environmental sensor for this widely used class of pesticides.
authors.affiliation: Division of Environmental Health Sciences School of Public Health, University of Minnesota, MMC 807, Room 1260 Mayo, 420 Delaware Street, S.E, Minneapolis, MN 55455-0392, USA. jadgate@umn.edu
authors.forename: John L
authors.initials: JL
authors.lastname: Adgate
authors.forename: Andrea
authors.initials: A
authors.lastname: Barteková
authors.forename: Peter C
authors.initials: PC
authors.lastname: Raynor
authors.forename: J Girard
authors.initials: JG
authors.lastname: Griggs
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Ryan
authors.forename: Bharat R
authors.initials: BR
authors.lastname: Acharya
authors.forename: Carla J
authors.initials: CJ
authors.lastname: Volkmann
authors.forename: Darrin D
authors.initials: DD
authors.lastname: Most
authors.forename: Siyi
authors.initials: S
authors.lastname: Lai
authors.forename: Michael D
authors.initials: MD
authors.lastname: Bonds
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D006813:Humidity; D050866:Liquid Crystals; D010755:Organophosphates / Q000032:analysis*; D010575:Pesticides / Q000032:analysis*; D013696:Temperature
chemical_list: D000393:Air Pollutants; D010755:Organophosphates; D010575:Pesticides