S. M. Rahmat Ullah

Fat Extraction from Acid- and Base-Hydrolyzed Food Samples Using Accelerated Solvent Extraction

This paper describes a new in-cell method for pursuing accelerated solvent extraction (ASE) prior to lipid analysis from food samples. It is difficult to pursue direct ASE with acid- or base-hydrolyzed samples due to the corrosive nature of the reagents and material limitations. In this study ion exchange based materials were used to remove acid or base reagents in-cell without compromising the recovery of lipids. The performance data are presented here for the new methods for lipid extraction for a variety of food samples and compared to the Mojonnier method. NIST Standard Reference Materials (SRM-1546 and SRM-1849) were used to validate the ASE methods. Excellent fat recoveries were obtained for the ASE methods. The new methods presented here enhance the utility of ASE and eliminate labor intensive protocols.

Monitoring and Source Apportionment of Fine Particulate Matter at Lindon, Utah

Under the EPA Science to Achieve Results (STAR) and the Environmental Monitoring for Public Access and Community Tracking (EMPACT) programs an intensive sampling campaign was performed during the month of August 2002 at the state of Utah Air Quality monitoring site in Lindon, Utah. The concentrations and composition of PM2.5 were measured using a variety of continuous samplers including a TEOM monitor to measure non-volatile PM2.5, a RAMS monitor to measure total PM2.5 including semi-volatile species, an ion-chromatographic based instrument to measure sulfate and nitrate, and an Anderson Aethalometer to measure elemental carbon and UV adsorption. Integrated PM2.5 data were collected using a PC-BOSS sampler, for the determination of detailed particle composition. Continuous gas phase concentrations of NO, NO2, NOx, H2O2, and O3 were also monitored. One-hour average PM2.5 data have been combined with continuous gas phase data to perform source apportionment using the EPA UNMIX program. Sources of fine particulate matter were apportioned into primary emission sources and secondary formation processes. Identified were primary mobile sources, including diesel and gasoline combustion vehicles, and both a day-time and night-time secondary source.

Automated Low-Pressure Carbonate Eluent Ion Chromatography System with Postsuppressor Carbon Dioxide Removal for the Analysis of Atmospheric Gases and Particles

We present a low-pressure, automated, semi-continuous Gas-Particle Ion Chromatograph to measure soluble ionogenic gases and soluble ionic constituents of PM2.5. The system utilizes a short separation column, an isocratic carbonate eluent and post suppressor CO2 removal. Measured constituents include ammonium, nitrate, and sulfate in the particle fraction, and nitric acid, sulfur dioxide, and ammonia among soluble gases. Two independent sampling channels are used. In one channel, a wet denuder collects soluble gases. In the second channel, following removal of large particles by a cyclone and soluble gases by a wet denuder, a hydrophobic filter-based particle collector collects and extracts the soluble components of PM2.5. The aqueous particle extract is aspirated by a peristaltic pump onto serial cation and anion preconcentrator columns. Gas samples are similarly loaded onto another set of serial cation and anion preconcentrator columns. The cation preconcentrator is eluted with NaOH and the evolved NH3 is passed across a membrane device whence it diffuses substantially into a deionized water receptor stream; the conductivity of the latter provides a measure of NH3 (NH4 +). The anion preconcentrator column(s) are subjected to automated periodic analysis by ion chromatography. This system provides data every 30 min for both particles (NO3 −, SO4 2 − and NH4 +) and gases (HNO3, SO2 and NH3). Gas and particle extract samples are each collected for 15 min. The analyses of the gas and particle samples are staggered 15 min apart. The limit of detection (S/N = 3) for NO3 −, SO4 2− and NH4 + are 2.6, 5.3, and 2.1 ng/m3, respectively.