Publications by authors named "Jeff M Small"
The National Institute of Standards and Technology (NIST) has a wide range of Standard Reference Materials (SRMs) which have values assigned for legacy organic pollutants and toxic elements. Existing SRMs serve as homogenous materials that can be used for method development, method validation, and measurement for contaminants that are now of concern. NIST and multiple groups have been measuring the mass fraction of a group of emerging contaminants, polyfluorinated substances (PFASs), in a variety of SRMs.
View Article and Find Full Text PDFThe cycling of sulfur in freshwater environments plays an important role in the cycling of metals. In this study, acid volatile sulfides were measured at nanomolar levels using a purge-and-trap preconcentration, followed by methylene blue derivatization with HPLC separation and UV-Vis detection. The limit of detection using the preconcentration step was 7.
View Article and Find Full Text PDFStandard reference materials (SRMs) are homogeneous, well-characterized materials used to validate measurements and improve the quality of analytical data. The National Institute of Standards and Technology (NIST) has a wide range of SRMs that have mass fraction values assigned for legacy pollutants. These SRMs can also serve as test materials for method development, method validation, and measurement for contaminants of emerging concern.
View Article and Find Full Text PDFArticle Synopsis
- The study examined concentrations of herbicides mecospop, dichlorprop, and metolachlor in Ontario streams during 2006-2007 and compared them to data from 2003-2004.
- Median levels of dichlorprop and metolachlor remained stable, but mecoprop concentrations increased in the later study.
- The findings regarding enantiomer signatures suggest that higher concentration samples showed more active forms of mecoprop, while lower concentrations indicated a mix of degradation processes affecting metolachlor.
The environmental ubiquity of perfluorooctane sulfonate (PFOS) is well-known. However, little is known about the environmental fate of individual PFOS isomers. In this study, we investigated the fractionation and the bioaccumulation of PFOS isomers in water, sediment and biota collected from Lake Ontario.
View Article and Find Full Text PDFChiral current-use herbicides in Ontario streams.
Environ Sci Technol
November 2008
Article Synopsis
- The study analyzed concentrations of mecoprop, dichlorprop, and metolachlor in 393 Ontario stream samples from 2003-2004, finding peak levels significantly higher in 2004 compared to 2003.
- Mecoprop levels were consistent across agricultural and urban watersheds, while metolachlor concentrations were significantly greater in agricultural areas, suggesting distinct usage patterns of these herbicides.
- The analysis of enantiomer fractions revealed a predominance of the R(+) form of mecoprop during the transitional period of herbicide replacement, with significant variations in metolachlor's stereoisomer ratios depending on the concentration and watershed type.