Assessing selected estrogens and xenoestrogens in Brazilian surface waters by liquid chromatography-tandem mass spectrometry

A sensitive and specific method was developed and validated for the determination of estrogen and xenoestrogen in surface waters using liquid chromatography followed by tandem mass spectrometry. Chromatographic separation was performed using ammonium hydroxide solutions in water and in methanol as mobile phase. Compounds were determined in a triple quadrupole mass spectrometer equipped with an electrospray ionization interface operating in the negative mode. Multiple reaction monitoring conditions were optimized for estrone, 17β-estradiol, estriol, 17α-ethinylestradiol, bisphenol A, 4-n-octylphenol, and 4-n-nonylphenol. The method was linear from 0.1 ng L^− 1 to 10 µgL^− 1. Limits of quantification varied between 0.1 and 3.1 ng L^− 1 and recoveries for a 50 ng L^− 1 spiked-surface water solution varied between 72 and 140%. The method was successfully used to determine estrogen and xenoestrogen levels in Brazilian water samples collected along the Atibaia River Basin, in the State of São Paulo. Concentrations of estrogens varied from 2.2 to 39 ng L^− 1. Bisphenol A was the most frequently detected compound as well as the only xenoestrogen in the samples with concentrations between 25 and 84 ng L^− 1.     

New materials for solid-phase extraction and multiclass high-performance liquid chromatographic analysis of pesticides in grapes

Sample preparation procedures which included the use of new aminopropyl (NH2) and octadecyl (C18) solid-phase extraction (SPE) sorbents are proposed for the simultaneous multiclass determination of the fungicide benomyl and of the herbicides tebuthiuron, diuron, simazine, atrazine, and ametryn in grapes, using single wavelength high-performance liquid chromatography. Sorbent preparation uses a fast, easy, and effective procedure to obtain silica-based materials, made by depositing polysiloxanes on a silica support followed by thermal immobilization. Recovery results of the compounds, after elution from the SPE cartridges, indicate that the most efficient system employed silica loaded with 40% of an aminofunctional polydimethylsiloxane as sorbent, using dichloromethane:methanol (95:5, v/v) as eluent. Method validation, carried out in agreement with International Conference on Harmonization directives, was performed at three fortification levels (100, 200, and 1000 microg kg(-1)). Limits of detection and quantification show that the method developed can be used to detect the pesticides at concentrations below the maximum residue levels established by Codex Alimentarius, the US Environmental Protection Agency, the European Union, and Brazilian legislation.     

Effect of Diets,Familial History,and Alternative Therapies on Genomic Instability of Breast Cancer Patients

This study evaluates a correlation between family history, micronutrients intake, and alternative therapies with genetic instability, before and during breast cancer treatment. For this study, a total of 150 women were selected. Among those, 50 women were breast cancer patients on chemotherapy, while 50 breast cancer patients were on radiotherapy, and 50 were healthy females. All the participants signed the informed consent form and answered the public health questionnaire. Samples of buccal epithelial and peripheral blood cells were collected and analyzed through micronucleus and comet assays. The cells were evaluated for apoptosis and DNA damage. Results showed the association of patients’ family history with an increase in toxicogenetic damage before and during cancer therapy. On the other hand, patients with late-onset cancer also presented genetic instability before and during therapy, along with those who did not take sufficient vegetables and alternative therapies. A positive correlation was observed between the genetic instability and alternative therapies, while inverse correlation was recorded with the vegetable consumption. Results clearly explain that the nutritional aspects and alternative therapies influence the genetic instability before and during cancer therapies especially in radiotherapy treated patients. Our data could be used for the monitoring therapies and management of breast cancer patients.

     

New Stationary Phase Prepared by Immobilization of a Copper-Amine Complex on Silica and Its Use for High Performance Liquid Chromatography

Chromatographic silica (10 μm) was chemically modified with the silylating agent: [3-(2-aminoethyl)aminopropyl]trimethoxysilane (AEAPTS). The reaction product was characterized by elemental analysis and infrared and ¹³C and ²⁹Si NMR spectra. The chemically modified silica was treated with Cu(II) in methanol medium. This cation was strongly adsorbed through complexation by the pendant ethylenediamine groups attached to the silica surface. The complex formed on the silica surface was shown to be stable in both aqueous and non-aqueous media. The aim of Cu(II) immobilization is to use this new material as a stationary phase in High Performance Liquid Chromatography (HPLC). Separations of synthetic mixtures of aromatic amines and of polyaromatic hydrocarbons were undertaken using 150×3.9 mm HPLC columns packed with the modified silica, with and without copper ions, to follow the influence of the cation on the chromatographic separation and to verify the efficiency of the new stationary phase for HPLC.     

A simple spectrophotometric procedure for the determination of antimony (III) and (V) in antileishmanial drugs

A spectrophotometric method for the selective determination of antimony (III) and (V) in antileishmanial drugs is described. The procedure is based on the reaction of Sb(III) with bromopyrogallol red (BPR) in neutral solution. As a consequence of the Sb-BPR complex formed, the absorbance of BPR, at 560 nm, decreases proportionally to the amount of Sb(III) in the analyte solution. The calculated apparent molar absorptivity and determination limits are 3.67 × 10⁴ L?·?cm^–1?·?mol^–1 and 1.65 × 10^–6 mol/L, respectively. Sb(V) is determined after reduction to Sb(III) by iodide. The Sb(V) content determined in ten samples of Glucantime varied from 75.40 ± 0.97 to 94.47 ± 1.0 mg/mL. Sb(III) was detected in all samples analyzed, and mean values ranged from 5.19 ± 0.16 to 10.52 ± 0.15 mg/mL. The method is suitable for the routine quality control of pharmaceutical formulations.     

Foliations by curves on threefolds

We study the conormal sheaves and singular schemes of one-dimensional foliations on smooth projective varieties X of dimension 3 and Picard rank 1. We prove that if the singular scheme has dimension 0, then the conormal sheaf is μ-stable whenever the tangent bundle $TX$ is stable, and apply this fact to the characterization of certain irreducible components of the moduli space of rank 2 reflexive sheaves on ${\mathbb{P}}^3$ and on a smooth quadric hypersurface $Q_3\subset {\mathbb{P}}^4$. Finally, we give a classification of local complete intersection foliations, that is, foliations with locally free conormal sheaves, of degree 0 and 1 on Q₃.