Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Todd Eichholz is active.

Publication


Featured researches published by Todd Eichholz.


Chemosphere | 2016

Single particle ICP-MS characterization of titanium dioxide, silver, and gold nanoparticles during drinking water treatment.

Ariel R. Donovan; Craig D. Adams; Yinfa Ma; Chady Stephan; Todd Eichholz; Honglan Shi

One of the most direct means for human exposure to nanoparticles (NPs) released into the environment is drinking water. Therefore, it is critical to understand the occurrence and fate of NPs in drinking water systems. The objectives of this study were to develop rapid and reliable analytical methods and apply them to investigate the fate and transportation of NPs during drinking water treatments. Rapid single particle ICP-MS (SP-ICP-MS) methods were developed to characterize and quantify titanium-containing, titanium dioxide, silver, and gold NP concentration, size, size distribution, and dissolved metal element concentration in surface water and treated drinking water. The effectiveness of conventional drinking water treatments (including lime softening, alum coagulation, filtration, and disinfection) to remove NPs from surface water was evaluated using six-gang stirrer jar test simulations. The selected NPs were nearly completely (97 ± 3%) removed after lime softening and alum coagulation/activated carbon adsorption treatments. Additionally, source and drinking waters from three large drinking water treatment facilities utilizing similar treatments with the simulation test were collected and analyzed by the SP-ICP-MS methods. Ti-containing particles and dissolved Ti were present in the river water samples, but Ag and Au were not present. Treatments used at each drinking water treatment facility effectively removed over 93% of the Ti-containing particles and dissolved Ti from the source water.


Talanta | 2015

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

Qihua Wu; Honglan Shi; Yinfa Ma; Craig D. Adams; Todd Eichholz; T Timmons; Hua Jiang

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.


Analytical and Bioanalytical Chemistry | 2016

Rapid simultaneous analysis of 17 haloacetic acids and related halogenated water contaminants by high-performance ion chromatography-tandem mass spectrometry

Runmiao Xue; Ariel R. Donovan; Honglan Shi; John Yang; Bin Hua; Enos C. Inniss; Todd Eichholz

AbstractHaloacetic acids (HAAs), which include chloroacetic acids, bromoacetic acids, and emerging iodoacetic acids, are toxic water disinfection byproducts. General screening methodology is lacking for simultaneously monitoring chloro-, bromo-, and iodoacetic acids. In this study, a rapid and sensitive high-performance ion chromatography-tandem mass spectrometry method for simultaneous determination of chloro-, bromo-, and iodo- acetic acids and related halogenated contaminants including bromate, bromide, iodate, and iodide was developed to directly analyze water samples after filtration, eliminating the need for preconcentration, and chemical derivatization. The resulting method was validated in both untreated and treated water matrices including tap water, bottled water, swimming pool water, and both source water and drinking water from a drinking water treatment facility to demonstrate application potential. Satisfactory accuracies and precisions were obtained for all types of tested samples. The detection limits of this newly developed method were lower or comparable with similar techniques without the need for extensive sample treatment requirement and it includes all HAAs and other halogenated compounds. This provides a powerful methodology to water facilities for routine water quality monitoring and related water research, especially for the emerging iodoacetic acids. Graphical abstractHigh performance ion chromatography-tandem mass spectrometry method for detection of haloacetic acids in water


Journal of Environmental Sciences-china | 2017

Simultaneous removal of ammonia and N-nitrosamine precursors from high ammonia water by zeolite and powdered activated carbon

Runmiao Xue; Ariel R. Donovan; Haiting Zhang; Yinfa Ma; Craig D. Adams; John Yang; Bin Hua; Enos C. Inniss; Todd Eichholz; Honglan Shi

When adding sufficient chlorine to achieve breakpoint chlorination to source water containing high concentration of ammonia during drinking water treatment, high concentrations of disinfection by-products (DBPs) may form. If N-nitrosamine precursors are present, highly toxic N-nitrosamines, primarily N-nitrosodimethylamine (NDMA), may also form. Removing their precursors before disinfection should be a more effective way to minimize these DBPs formation. In this study, zeolites and activated carbon were examined for ammonia and N-nitrosamine precursor removal when incorporated into drinking water treatment processes. The test results indicate that Mordenite zeolite can remove ammonia and five of seven N-nitrosamine precursors efficiently by single step adsorption test. The practical applicability was evaluated by simulation of typical drinking water treatment processes using six-gang stirring system. The Mordenite zeolite was applied at the steps of lime softening, alum coagulation, and alum coagulation with powdered activated carbon (PAC) sorption. While the lime softening process resulted in poor zeolite performance, alum coagulation did not impact ammonia and N-nitrosamine precursor removal. During alum coagulation, more than 67% ammonia and 70%-100% N-nitrosamine precursors were removed by Mordenite zeolite (except 3-(dimethylaminomethyl)indole (DMAI) and 4-dimethylaminoantipyrine (DMAP)). PAC effectively removed DMAI and DMAP when added during alum coagulation. A combination of the zeolite and PAC selected efficiently removed ammonia and all tested seven N-nitrosamine precursors (dimethylamine (DMA), ethylmethylamine (EMA), diethylamine (DEA), dipropylamine (DPA), trimethylamine (TMA), DMAP, and DMAI) during the alum coagulation process.


Chemosphere | 2017

Evaluation of thirteen haloacetic acids and ten trihalomethanes formation by peracetic acid and chlorine drinking water disinfection

Runmiao Xue; Honglan Shi; Yinfa Ma; John Yang; Bin Hua; Enos C. Inniss; Craig D. Adams; Todd Eichholz

Free chlorine is a commonly used disinfectant in drinking water treatment. However, disinfection by-products (DBPs) are formed during water disinfection. Haloacetic acids (HAAs) and trihalomethanes (THMs) are two major groups of DBPs. Iodo-HAAs and iodo-THMs (I-HAAs and I-THMs) are formed during the disinfection of the water containing high levels of iodide and are much more toxic than their chlorinated and brominated analogs. Peracetic acid (PAA) is a strong antimicrobial disinfectant that is expected to reduce the formation of HAAs and THMs during disinfection. In this study, the formations of thirteen HAAs and ten THMs, including the iodinated forms, have been investigated during PAA disinfection and chlorination as the comparison. The DBP formations under different iodide concentrations, pHs, and contact times were systematically investigated. Two types of commercial PAAs containing different concentrations of PAA and hydrogen peroxide (H2O2) were studied. A solid-phase microextraction gas chromatography-mass spectrometry method was upgraded for THM analysis including I-THMs. HAAs were analyzed by following a recently developed high performance ion chromatography-tandem mass spectrometry method. Results show that the ratio of PAA and H2O2 concentration significantly affect the formation of I-THMs and I-HAAs. During PAA disinfection with lower PAA than H2O2, no detectable levels of THMs and HAAs were observed. During PAA disinfection with higher PAA than H2O2, low levels of monoiodoacetic acid, diiodoacetic acid, and iodoform were formed, and these levels were enhanced with the increase of iodide concentration. No significant quantities of chloro- or bromo-THMs and HAAs were formed during PAA disinfection treatment.


Chemosphere | 2018

Fate of nanoparticles during alum and ferric coagulation monitored using single particle ICP-MS

Ariel R. Donovan; Craig D. Adams; Yinfa Ma; Chady Stephan; Todd Eichholz; Honglan Shi

In this study, aluminum sulfate, ferric sulfate, ferric chloride, and poly(diallyldimethylammonium chloride) (pDADMAC) coagulation removal of citrate-stabilized silver and gold nanoparticles (NPs) and uncoated titanium dioxide, cerium dioxide, and zinc oxide NPs was investigated using a single particle (SP) ICP-MS direct monitoring technique. Zone 2 (charge neutralization) coagulation was performed in river water and more commonly used Zone 4 (sweep floc) coagulation was performed in both river and lake water with environmentally relevant concentrations of selected NPs added. SP-ICP-MS was used to detect NP and dissolved species, characterize the size distribution, and quantify particle concentration as well as dissolved species before and after treatments. Other parameters including pH, dissolved organic carbon, turbidity, and UV254 absorbance were monitored to characterize treatment efficiency. Charge neutralization (Zone 2) coagulation resulted in 48-85% removal of citrate-stabilized NPs and 90-99% removal of uncoated NPs from river water. Sweep floc (Zone 4) coagulation in river water resulted in 36-94% removal of citrate-stabilized NPs and 91-99% removal of uncoated NPs both with and without polymer addition. Zone 4 coagulation conditions in lake water resulted in 77-98% removal of citrate-stabilized NPs and 59-96% removal of uncoated NPs without polymer. These results indicate that NP removal depends on NP surface and stability, the nature of the source water, and the coagulant type and approach.


Urban Water Journal | 2017

Detection, occurrence, and removal of selected pharmaceuticals in Missouri source and finished drinking waters

Ruipu Mu; Honglan Shi; Craig D. Adams; Todd Eichholz; Yinfa Ma

Abstract A simple, sensitive, and selective solid phase extraction – ultra-fast liquid chromatography – tandem mass spectrometry (SPE-UFLC-MS/MS) method was developed and applied for the analysis of selected important pharmaceutical compounds in source and finished drinking waters. The method detected the following six pharmaceuticals, cotinine, cephapirin, ciprofloxacin, enrofloxacein, azithromycin, and diphenhydramine, at sub-μg/L level in multiple water matrices after pre-concentration by SPE. Cotinine-d3 and 13C315 N-Ciprofloxacin were used as internal standards for accurate quantitation. This method was validated through spike recoveries (67–129%), reproducibility (RSD: 2.3–15.7%), and method detection limits (MDLs: 2–5 ng/L). The method was used to test for occurrence of these pharmaceuticals in source and drinking waters from 13 Missouri water treatment facilities in four different seasons. In general, higher detection frequency and concentrations of pharmaceuticals were observed in colder months due presumably to less dilution (at lower flows) and slower degradation. The PPCP removals by different activated carbons were also evaluated. The occurrence and removal results in this study provide valuable information to help water treatment facilities taking appropriate strategies for better control of trace pharmaceuticals in drinking water.


Analytical and Bioanalytical Chemistry | 2016

Detection of zinc oxide and cerium dioxide nanoparticles during drinking water treatment by rapid single particle ICP-MS methods

Ariel R. Donovan; Craig D. Adams; Yinfa Ma; Chady Stephan; Todd Eichholz; Honglan Shi


Environmental Science and Pollution Research | 2015

Simultaneous detection of perchlorate and bromate using rapid high-performance ion exchange chromatography–tandem mass spectrometry and perchlorate removal in drinking water

Danielle M. West; Ruipu Mu; Sanjeewa Gamagedara; Yinfa Ma; Craig D. Adams; Todd Eichholz; Joel G. Burken; Honglan Shi


Separation and Purification Technology | 2015

Removal of N-nitrosamine Precursors in Drinking Water System using Adsorption Methods

Qihua Wu; Honglan Shi; Yinfa Ma; Craig D. Adams; Hua Jiang; Jianmin Wang; Todd Eichholz; T Timmons

Collaboration


Dive into the Todd Eichholz's collaboration.

Top Co-Authors

Avatar

Honglan Shi

Missouri University of Science and Technology

View shared research outputs
Top Co-Authors

Avatar

Yinfa Ma

Missouri University of Science and Technology

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Ariel R. Donovan

Missouri University of Science and Technology

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Runmiao Xue

Missouri University of Science and Technology

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Haiting Zhang

Missouri University of Science and Technology

View shared research outputs
Top Co-Authors

Avatar

Hua Jiang

Missouri University of Science and Technology

View shared research outputs
Researchain Logo
Decentralizing Knowledge