T Timmons

Investigation of Pharmaceuticals in Missouri Natural and Drinking Water Using High Performance Liquid Chromatography-Tandem Mass Spectrometry

A comprehensive method has been developed and validated in two different water matrices for the analysis of 16 pharmaceutical compounds using solid phase extraction (SPE) of water samples, followed by liquid chromatography coupled with tandem mass spectrometry. These 16 compounds include antibiotics, hormones, analgesics, stimulants, antiepileptics, and X-ray contrast media. Method detection limits (MDLs) that were determined in both reagent water and municipal tap water ranged from 0.1 to 9.9 ng/L. Recoveries for most of the compounds were comparable to those obtained using U.S. EPA methods. Treated and untreated water samples were collected from 31 different water treatment facilities across Missouri, in both winter and summer seasons, and analyzed to assess the 16 pharmaceutical compounds. The results showed that the highest pharmaceutical concentrations in untreated water were caffeine, ibuprofen, and acetaminophen, at concentrations of 224, 77.2, and 70 ng/L, respectively. Concentrations of pharmaceuticals were generally higher during the winter months, as compared to those in the summer due, presumably, to smaller water quantities in the winter, even though pharmaceutical loadings into the receiving waters were similar for both seasons.

Oxidative removal of selected endocrine-disruptors and pharmaceuticals in drinking water treatment systems, and identification of degradation products of triclosan

The potential occurrences of endocrine-disrupting compounds (EDCs), as well as pharmaceuticals, are considered to be emerging environmental problems due to their persistence and continuous input into the aquatic ecosystem, even at only trace concentrations. This study systematically investigated the oxidative removal of eight specially selected ECDs and pharmaceuticals by comparing their relative reactivity as a function of different oxidative treatment processes (i.e., free chlorine, ozone, monochloramine, and permanganate) under various pH conditions. For the oxidative removal study, EDC and pharmaceutical standards were spiked into both deionized water and natural water, followed by treatment using common oxidants at typical water treatment concentrations. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for identification and quantification. The removal efficiency of the EDCs and pharmaceuticals varied significantly between oxidation processes. Free chlorine, permanganate, and ozone treatments were all highly effective at the elimination of triclosan and estrone, while they were not effective for removing ibuprofen, iopromide, and clofibric acid. Monochloramine (at a dose of 3mg/L) was mostly ineffective in eliminating any of the selected EDCs and pharmaceuticals under the tested conditions. pH also played an important role in the removal efficiency of the EDCs and pharmaceuticals during free chlorine, permanganate, and ozone treatments. Additionally, the study identified the oxidation products of triclosan by permanganate, and 2,4-dichlorophenol was identified as the major oxidation product of triclosan by permanganate in drinking water system treatment. Furthermore, 2,4-dichlorophenol was further degradated to 4,5-dichloro-2-(2,4-dichlorophenoxy)phenol and/or 5,6-dichloro-2-(2,4-dichlorophenoxy)phenol. The kinetics for this reaction indicated that the reaction was first order in the drinking water system.

Release and Removal of Microcystins from Microcystis during Oxidative-, Physical- and UV-based Disinfection

Cyanotoxins released from cyanobacteria (or blue-green algae) pose an increasing public health risk worldwide. In this study, the release of the cyanotoxin microcystin, from Microcystis aeruginosa due to oxidative, ultraviolet (UV), and physical impacts during water treatment was studied. Additionally, the relative and absolute rates of chemical oxidation of the six microcystins were determined for selected oxidants. Cell viability was measured based on treatment dosage using a fluorescence method. The specific chemical oxidants studied were free chlorine ( HOCl/ OCl− ) , chlorine dioxide, ozone, permanganate, and monochloramine. UV energy was at 254 nm. For chemical oxidants and UV, the exposures or doses examined were selected based on typical disinfection dosages. Other treatments examined included low and high salinity, ultrasonics, and physical blending. Free chlorine, permanganate, chlorine dioxide, monochloramine, and ozone were observed to at least partially disinfect the cyanobacteria, while the ...

Effects of oxidative and physical treatments on inactivation of Cylindrospermopsis raciborskii and removal of cylindrospermopsin

The presence of toxic cyanobacterial blooms (or blue-green algae) in water bodies used either as drinking water or for recreational purposes may present serious health risks for the human population. In this study, the removal of the chemical toxin, cylindrospermopsin, via free chlorine, chlorine dioxide, monochloramine, permanganate, ozone, and UV irradiation was studied. Ozone and free chlorine were found to be highly effective for cylindrospermopsion removal while the other disinfectants were ineffective. Ozone and free chlorine were also determined to be highly effective for the inactivation of the cyanobacteria, Cylindrospermopsis raciborskii, at typical water treatment exposures, chlorine dioxide, monochloramine, and permanganate were only marginally effective at inactivation of Cylindrospermopsis raciborskii.

Determination of secondary and tertiary amines as N-nitrosamine precursors in drinking water system using ultra-fast liquid chromatography-tandem mass spectrometry.

N-Nitrosamines are potent mutagenic and carcinogenic emerging water disinfection by-products (DBPs). The most effective strategy to control the formation of these DBPs is minimizing their precursors from source water. Secondary and tertiary amines are dominating precursors of N-nitrosamines formation during drinking water disinfection process. Therefore, the screening and removal of these amines in source water are very essential for preventing the formation of N-nitrosamines. A rapid, simple, and sensitive ultrafast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method has been developed in this study to determine seven amines, including dimethylamine, ethylmethylamine, diethylamine, dipropylamine, trimethylamine, 3-(dimethylaminomethyl)indole, and 4-dimethylaminoantipyrine, as major precursors of N-nitrosamines in drinking water system. No sample preparation process is needed except a simple filtration. Separation and detection can be achieved in 11 min per sample. The method detection limits of selected amines are ranging from 0.02 μg/L to 1 μg/L except EMA (5 μg/L), and good calibration linearity was achieved. The developed method was applied to determine the selected precursors in source water and drinking water samples collected from Midwest area of the United States. In most of water samples, the concentrations of selected precursors of N-nitrosamines were below their method detection limits. Dimethylamine was detected in some of water samples at the concentration up to 25.4 μg/L.

Simultaneous Screening of Herbicide Degradation Byproducts in Water Treatment Plants using High Performance Liquid Chromatography-Tandem Mass Spectrometry

Currently, herbicides are widely used in various combinations at many stages of cultivation and during postharvest storage. There are increasing concerns about the public health impact of herbicide degradation byproducts that may be present in water bodies used either as drinking water or for recreational purposes. This work investigated the sulfonic acid and oxanilic acid degradation products of metolachlor, alachlor, acetochlor, and propachlor in a variety of water bodies. The objective was to develop a fast, accurate, and easy method for quantitative analysis of herbicide degradation products using liquid chromatography with tandem mass spectrometry without solid phase extraction, but performing levels of detection lower than those obtained in previous studies with solid phase extraction. This research also screened 68 water samples, both untreated source water and treated water, from 34 water treatment plants in Missouri. Finally, it examined seasonal trends in levels of those degradation products by collecting and testing samples monthly. This highly sensitive method can analyze these degradation products to low ng/L levels. The method limit of quantification ranges from 0.04 to 0.05 ppb for each analyte; and quantitative analyses show a precision with RSDs of around 0.6% to 3% in treated water and 2% to 19% in untreated source water. Concentrations of alachlor ESA, acetochlor OA, metolachlor OA, and metolachlor ESA were detected from the Missouri River and the Mississippi River water bodies in summer time. Occurrences of these compounds in treated water samples are all lower than those in the untreated source water samples.

Investigation of removal of N-nitrosamines and their precursors in water treatments using activated carbon nanoparticles

N-nitrosamines have been detected in various water types. A strategy for removal of this group of compounds should be taken to reduce the health risks for humans. In this study, a fast and sensitive LC-MS/MS method was developed for quantitative analysis of nine N-nitrosamines and four precursors in a single sample. The Method Detection Limits (MDLs) in natural water ranged from 0.05 μg/L to 5 μg/L without using SPE pre-concentration. Three different types of activated carbon nanoparticles (NPs) (bamboo, charcoal and coconut shell as raw materials) were used to carry out removal experiments in two different pHs (pH 6.6 and 8.6). The results indicated that coconut shell-based activated carbon NPs had higher removal efficiency than the other two with a typical dosage of activated carbon NPs, at a typical contact time of 4 hours. No significant differences in removal efficiency between the two selected pH values were observed.