Stability considerations of aspartame in the direct analysis of artificial sweeteners in water samples using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS)

A HPLC-MS/MS method is presented for the simultaneous determination of frequently used artificial sweeteners (ASs) and the main metabolite of aspartame (ASP), diketopiperazine (DKP), in environmental water samples using the direct-injection (DI) technique, thereby achieving limits of quantification (LOQ) of 10 ng L⁻¹. For a reliable quantification of ASP pH should be adjusted to 4.3 to prevent formation of the metabolite. Acesulfame (ACE), saccharin (SAC), cyclamate (CYC) and sucralose (SUC) were ubiquitously found in water samples. Highest concentrations up to 61 μg L⁻¹ of ACE were found in wastewater effluents, followed by surface water with concentrations up to 7 μg L⁻¹, lakes up to 600 ng L⁻¹ and groundwater and tap water up to 70 ng L⁻¹. The metabolite DKP was only detected in wastewater up to 200 ng L⁻¹ and at low detection frequencies.     

Depollution benchmarks for capacitors,batteries and printed wiring boards from waste electrical and electronic equipment (WEEE)

The article compiles and analyses sample data for toxic components removed from waste electronic and electrical equipment (WEEE) from more than 30 recycling companies in Switzerland over the past ten years. According to European and Swiss legislation, toxic components like batteries, capacitors and printed wiring boards have to be removed from WEEE. The control bodies of the Swiss take back schemes have been monitoring the activities of WEEE recyclers in Switzerland for about 15 years. All recyclers have to provide annual mass balance data for every year of operation. From this data, percentage shares of removed batteries and capacitors are calculated in relation to the amount of each respective WEEE category treated. A rationale is developed, why such an indicator should not be calculated for printed wiring boards. The distributions of these de-pollution indicators are analysed and their suitability for defining lower threshold values and benchmarks for the depollution of WEEE is discussed. Recommendations for benchmarks and threshold values for the removal of capacitors and batteries are given.     

Sources of pesticides in surface waters in Switzerland: pesticide load through waste water treatment plants--current situation and reduction potential

Concentrations of pesticides in Swiss rivers and lakes frequently exceed the Swiss quality goal of 0.1 microg/l for surface waters. In this study, concentrations of various pesticides (e.g., atrazine, diuron, mecoprop) were continuously measured in the effluents of waste water treatment plants and in two rivers during a period of four months. These measurements revealed that in the catchment of Lake Greifensee, farmers who did not perfectly comply with 'good agricultural practice' caused at least 14% of the measured agricultural herbicide load into surface waters. Pesticides, used for additional purposes in urban areas (i.e. protection of materials, conservation, etc.), entered surface waters up to 75% through waste water treatment plants.     

Comparing solid phase extraction and direct injection for the analysis of ultra-trace levels of relevant explosives in lake water and tributaries using liquid chromatography-electrospray tandem mass spectrometry

Off-line solid phase extraction and direct injection analysis were evaluated for the determination of traces of explosives such as TNT and its mono and diamino metabolites, HMX, RDX, nitroglycerin and PETN in lake water and tributaries applying liquid chromatography-electrospray tandem mass spectrometry. Improved chromatographic separation was achieved on a phenyl based stationary phase with baseline resolution of the mono- and diamino metabolites of TNT. Identification and quantification of the target compounds was performed by multiple reaction monitoring applying electrospray ionization in either the positive mode for the diaminometabolites of TNT or the negative mode for all other compounds. An extensive method validation was performed and limits of quantification were obtained for the explosives in preconcentrated lake water samples from 0.03 to 1 ng l(-1) and 0.1 to 5 ng l(-1) in river water. Direct injection analysis revealed comparable results to preconcentrated water samples for the most persistent explosives. Analysis of lake water samples collected at different depths showed the presence of HMX, RDX and PETN at concentrations from 0.1 to 0.4 ng l(-1). The analysis of main tributaries revealed concentrations from 0.1 to 0.9 ng l(-1) of the same compounds. They seem to be responsible for the contamination of the explosives in the lakes.