The behavior of pharmaceutically active compounds and contrast agents during wastewater treatment - Combining sampling strategies and analytical techniques: A critical review.

Increasing consumption of pharmaceuticals and the respective consequences for the aquatic environment have been the focus of many studies over the last thirty years. Various aspects in this field were investigated, considering diverse pharmaceutical groups and employing a wide range of research methodologies. Various questions from the perspectives of different research areas were devised and answered, resulting in a large mix of individual findings and conclusions.

Spatial and temporal trends in the fate of silver nanoparticles in a whole-lake addition study.

Studies of the fate and toxicity of nanoparticles, including nanosilver (AgNPs), have been primarily conducted using bench scale studies over relatively short periods of time. To better understand the fate of AgNPs in natural aquatic ecosystems over longer time scales and ecological settings, we released suspensions of AgNPs (30-50 nm, capped with polyvinylpyrrolidone) into a boreal lake at the Experimental Lakes Area in Canada. Approximately 9 kg of silver was added from a shoreline point source from June to October 2014, which resulted in total Ag (TAg) concentrations of about 10 μg L-1 or less.

A Method for Preparing Silver Nanoparticle Suspensions in Bulk for Ecotoxicity Testing and Ecological Risk Assessment.

Methods are needed to prepare stable suspensions of engineered nanoparticles in aqueous matrixes for ecotoxicity testing and ecological risk assessments. We developed a novel method of preparing large volumes of silver nanoparticles (AgNP) in suspension using a commercially available rotor-stator dispersion mill. AgNP in powder form (PVP capped, 30-50 nm) was suspended in deionized water and natural lake water at 1 g/L and the addition of 0.

Carbon Nanotube Integrative Sampler (CNIS) for passive sampling of nanosilver in the aquatic environment.

Nanomaterials such as nanosilver (AgNP) can be released into the aquatic environment through production, usage, and disposal. Sensitive and cost-effective methods are needed to monitor AgNPs in the environment. This work is hampered by a lack of sensitive methods to detect nanomaterials in environmental matrixes.

Single particle ICP-MS as a tool for determining the stability of silver nanoparticles in aquatic matrixes under various environmental conditions, including treatment by ozonation.

Silver nanoparticles (AgNPs) are used in a large number of consumer products due to their antimicrobial and antifungal properties, and these materials may be discharged into municipal wastewater. Wastewater treatment, including advanced oxidation processes (AOPs), may modify the forms of silver in wastewater before they are discharged into surface waters. In addition, little is known about the changes in AgNPs that occur in natural waters under different environmental conditions.

Gadolinium-uptake by aquatic and terrestrial organisms-distribution determined by laser ablation inductively coupled plasma mass spectrometry.

Gadolinium (Gd) based contrast agents (CA) are used to enhance magnetic resonance imaging. As a consequence of excretion by patients and insufficient elimination in wastewater treatment plants they are detected in high concentrations in surface water. At present, little is known about the uptake of these species by living organisms in aquatic systems.

Sensitive quantification of gadolinium-based magnetic resonance imaging contrast agents in surface waters using hydrophilic interaction liquid chromatography and inductively coupled plasma sector field mass spectrometry.

The application of gadolinium(Gd)-based contrast agents to support medical examinations by magnetic resonance imaging (MRI) results in a large input of Gd into the environment. The long-term effects of the anthropogenic Gd anomaly, especially on aqueous ecosystems, are mostly unknown. The identification and quantification of Gd-based contrast agents in the aquatic environment requires the use of powerful methods of speciation analysis.

Determination of gadolinium-based MRI contrast agents in biological and environmental samples: a review.

The development of analytical methods and strategies to determine gadolinium and its complexes in biological and environmental matrices is evaluated in this review. Gadolinium (Gd) chelates are employed as contrast agents for magnetic resonance imaging (MRI) since the 1980s. In general they were considered as safe and well-tolerated, when in 2006, the disease nephrogenic systemic fibrosis (NSF) was connected to the administration of MRI contrast agents based on Gd.

Speciation and isotope dilution analysis of gadolinium-based contrast agents in wastewater.

The fate of Gadolinium (Gd)-based contrast agents for magnetic resonance imaging (MRI) during sewage treatment was investigated. The total concentration of Gd in influent and effluent 2 and 24 h composite samples was determined by means of isotope dilution analysis. The balancing of Gd input and output of a sewage plant over seven days indicated that approximately 10% of the Gd is removed during treatment.

Speciation of Gd-based MRI contrast agents and potential products of transmetalation with iron ions or parenteral iron supplements.

The risk of transmetalation reactions between gadolinium complexes used as contrast agents for magnetic resonance imaging (MRI) and iron ions is examined under physiological conditions. A fast separation of gadopentetate (Gd-DTPA) and gadoterate (Gd-DOTA) and the respective Fe transmetalation products was accomplished by high-performance liquid chromatography. For detection, the LC system was coupled to an Orbitrap electrospray ionization mass spectrometer to achieve a detection limit as low as 50 nmol/L for Fe-DTPA.

Identification and quantification of potential metabolites of Gd-based contrast agents by electrochemistry/separations/mass spectrometry.

Oxidative and potentially metabolic pathways of the five most frequently used contrast agents for magnetic resonance imaging (MRI) based on gadolinium (Gd) are examined. The oxidation of gadopentetate (Gd-DTPA) was studied with a focus on electrochemical oxidation coupled to analytical separation methods and mass spectrometric detection. Mass voltammograms generated with online electrochemistry/electrospray ionization mass spectrometry (EC/ESI-MS) gave a first overview of oxidation products.

Simple and rapid quantification of gadolinium in urine and blood plasma samples by means of total reflection X-ray fluorescence (TXRF).

A simple and rapid method to determine gadolinium (Gd) concentrations in urine and blood plasma samples by means of total reflection X-ray fluorescence (TXRF) was developed. With a limit of detection (LOD) of 100 μg L(-1) in urine and 80 μg L(-1) in blood plasma and a limit of quantification (LOQ) of 330 μg L(-1) in urine and 270 μg L(-1) in blood plasma, it allows analyzing urine samples taken from magnetic resonance imaging (MRI) patients during a period of up to 20 hours after the administration of Gd-based MRI contrast agents by means of TXRF. By parallel determination of the urinary creatinine concentration, it was possible to monitor the excretion kinetics of Gd from the patient's body.

Quantification and excretion kinetics of a magnetic resonance imaging contrast agent by capillary electrophoresis-mass spectrometry.

A novel method for the analysis of Gadolinium-based contrast agents in complex clinical matrices is presented. Three commonly applied ionic contrast agents for magnetic resonance imaging were separated by CE and detected by ESI-MS. Blank urine samples were spiked with Dotarem (Gd-DOTA, Gadolinium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), Magnevist (Gd-DTPA, Gadolinium-diethylenetriaminepentaacetic acid) and Multihance (Gd-BOPTA, Gadolinium-benzyloxymethyl-diethylenetriaminepentaacetic acid) to determine the recovery rates.

Analysis of the contrast agent Magnevist and its transmetalation products in blood plasma by capillary electrophoresis/electrospray ionization time-of-flight mass spectrometry.

To study transmetalation effects of the gadolinium-based contrast agent Magnevist (Gd-DTPA), the first analytical method for the simultaneous determination of Gd-DTPA and its transmetalation products in complex clinical samples was developed. The high separation efficiency of capillary electrophoresis (CE) was employed to separate Gd-DTPA, Fe-DTPA, Cu-DTPA, Zn-DTPA, and the free DTPA (diethylenetriaminepentaacetic acid) ligand. The coupling of CE with electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) provided the required sensitivity and excellent selectivity for the analysis of complex samples, such as blood plasma and whole blood.

Speciation analysis of gadolinium-based MRI contrast agents in blood plasma by hydrophilic interaction chromatography/electrospray mass spectrometry.

The first analytical method for simultaneous speciation analysis of five of the most important gadolinium-based magnetic resonance imaging (MRI) contrast agents in blood plasma samples was developed. Gd-DTPA (Magnevist), Gd-BT-DO3A (Gadovist), Gd-DOTA (Dotarem), Gd-DTPA-BMA (Omniscan), and Gd-BOPTA (Multihance) were separated by hydrophilic interaction liquid chromatography (HILIC) and detected with electrospray mass spectrometry (ESI-MS). Spiking experiments of blank plasma with Magnevist and Gadovist were performed to determine the analytical figures of merit and the recovery rates.