Cardiovascular drugs in environmental waters and wastewaters: method optimization and real sample analysis.

A sensitive method for determination of the eight most prescribed drugs used in combined cardiovascular therapy in Serbia was developed and optimized. The method was based on SPE followed by LC/ion trap-MS/MS with positive electrospray ionization. Parameters that affect the SPE were optimized, such as the eluent, sample pH, and sample volume.

Methods for monitoring of pesticide residues in water: current status and recent trends.

An overview of analytical methods currently used for the determination of pesticide residues in water samples is presented. As liquid chromatography and gas chromatography, coupled to mass spectrometry, are considered to be the most appropriate techniques for determination of pesticides in environmental waters, the most recent developments and applications in this field are discussed, as well as the extraction procedures employed for analyte isolation and preconcentration.

Pharmaceutical residues in the Danube River Basin in Serbia - a two-year survey.

Pharmaceuticals are emerging contaminants with damaging effects to the environment and human health. Their presence in surface and especially groundwaters is regarded as detrimental, as they can ultimately reach drinking water. The aim of this work was to monitor pharmaceutical contamination of the Danube River and its tributaries in Serbia, and to assess the potential of their passing through all natural filtrations and reaching the groundwater.

Monomer elution from nanohybrid and ormocer-based composites cured with different light sources.

Objectives: To study monomer elution from four resin-based composites (RBCs) cured with different light sources.

Methods: Twenty-eight premolars were randomly allocated to four groups. Standardized cavities were prepared and restored with a nanohybrid (Filtek Supreme XT or Tetric EvoCeram), an ormocer (Admira) or a microhybrid RBC (Filtek Z250) which served as control.

Determination of pesticides in surface and ground waters by liquid chromatography-electrospray-tandem mass spectrometry.

The sensitive multiresidual analytical method for simultaneous analysis of 14 most commonly used agricultural pesticides in Serbia was developed and optimized. The selected insecticides, fungicides and herbicides belong to seven chemical classes (organophosphates, neonicotinoids, carbamates, diacylhydrazines, benzimidazoles, triazines and phenylureas). The method was based on solid-phase extraction followed by liquid chromatography-tandem mass spectrometry.

Determination of selected pesticides in environmental water by employing liquid-phase microextraction and liquid chromatography-tandem mass spectrometry.

An optimised extraction and cleanup method for the analysis of pesticide in natural water samples is presented. Sixteen pesticides of different polarity and from the different chemical classes (organophosphates, triazines, benzimidazoles, carbamates, carbamides, neonicotinoides, methylureas, phenylureas and benzohydrazides), most frequently used in Serbia, were selected for the analysis. Liquid-phase microextraction in a single hollow fibre (HF-LPME) has been applied for sample preparation.

Determination of multiple pharmaceutical classes in surface and ground waters by liquid chromatography-ion trap-tandem mass spectrometry.

This paper describes development, optimization and application of analytical method for determination and reliable confirmation of nineteen pharmaceuticals from different therapeutic classes (antibiotics--beta-lactams, cephalosporines, sulfonamides, macrolides and tetracyclines; benzodiazepines; antiepileptics and analgoantipyretics) in surface and ground waters at ng l(-1) levels. Water samples were prepared using solid-phase extraction and extracts were analyzed by liquid chromatography-ion trap-tandem mass spectrometry with electrospray ionization in both positive and negative ionization mode. The efficiency of ten different SPE cartridges to extract diverse compounds from water was tested.

Optimization of artificial neural network for retention modeling in high-performance liquid chromatography.

An artificial neural network (ANN) model for the prediction of retention times in high-performance liquid chromatography (HPLC) was developed and optimized. A three-layer feed-forward ANN has been used to model retention behavior of nine phenols as a function of mobile phase composition (methanol-acetic acid mobile phase). The number of hidden layer nodes, number of iteration steps and the number of experimental data points used for training set were optimized.

Study on the formation of an amoxicillin adduct with methanol using electrospray ion trap tandem mass spectrometry.

The possibility of using the protonated methanol-adduct of antimicrobial amoxicillin for its identification and quantification at residue levels has been investigated, since it is impossible to completely suppress the formation of these adducts when methanol is present in the solvent system. This process has been monitored over time and as a function of concentration. It was determined that adducts were instantly formed and that the abundance of the protonated methanol-adduct at m/z 398 increased at the expense of the protonated molecule m/z 366 with storage time.

Determination of carbendazim residues in fruit juices by liquid chromatography-tandem mass spectrometry.

In this paper a rapid optimized method for routine analysis of carbendazim residues in fruit juices is reported. The procedure is based on matrix solid-phase dispersion (MSPD) with diatomaceous earth and analysis of the extract by liquid chromatography-tandem mass spectrometry, with electrospray ionization (LC-ESI-MS/MS). In the method optimization, finding of the optimal pH for the extraction of carbendazim from juice was particularly critical.