Determination of fluorine in herbs and water samples by molecular absorption spectrometry after preconcentration on nano-TiO2 using ultrasound-assisted dispersive micro solid phase extraction.

This work presents ultrasound-assisted dispersive micro solid phase extraction (USA DMSPE) for preconcentration of fluorine (F) in water and herb samples. TiO2 nanoparticles (NPs) were used as an adsorbent. The determination with slurry sampling was performed via molecular absorption of calcium monofluoride (CaF) at 606.440 nm using a high-resolution continuum source electrothermal absorption spectrometry (HR-CS ET MAS). Several factors influencing the efficiency of the preconcentration technique, such as the amount of TiO2, pH of sample solution, ultrasonication and centrifugation time and TiO2 slurry solution preparation before injection to HR-CS ET MAS, were investigated in detail. The conditions of detection step (wavelength, calcium amount, pyrolysis and molecule-forming temperatures) were also studied. After extraction, adsorbent with the analyte was mixed with 200 µL of H2O to prepare a slurry solution. The concentration limit of detection was 0.13 ng mL-1. The achieved preconcentration factor was 7. The relative standard deviations (RSDs, %) for F in real samples were 3-15%. The accuracy of this method was evaluated by analyses of certified reference materials after spiking: INCT-MPH-2 (Mixed Polish Herbs), INCT-SBF-4 (Soya Bean Flour), ERM-CAO11b (Hard Drinking Water) and TMDA-54.5 (Lake Ontario Water). The measured F contents in reference materials were in satisfactory agreement with the added amounts, and the recoveries were found to be 97-109%. Under the developed extraction conditions, the proposed method has been successfully applied for the determination of F in real water samples (lake, sea, tap water) and herbs.

Positive and negative aspects of green coffee consumption - antioxidant activity versus mycotoxins.

BACKGROUND: The quality of coffee depends not only on the contents of healthy compounds but also on its contamination with microorganisms that can produce mycotoxins during development, harvesting, preparation, transport and storage. RESULTS: The antioxidant activity of green coffee brews measured in this study by ABTS, DPPH and Folin-Ciocalteu assays showed that coffee extracts from Robusta beans possessed higher activity in all assays than extracts from Arabica beans. The occurrence of ochratoxin A and aflatoxins (B1, B2, G1 and G2) in green coffee beans was studied using liquid chromatography/mass spectrometry. Apart from mycotoxins, the content of ergosterol as a marker indicating fungal occurrence was also determined. Among aflatoxins, aflatoxin B1 was the dominant mycotoxin in coffee bean samples, with the highest level at 17.45 ng g-1 . Ochratoxin A was detected in four samples at levels ranging from 1.27 to 4.34 ng g-1 , and fungi potentially producing this toxin, namely Aspergillus oryzae, Alternaria sp., Aspergillus foetidus, Aspergillus tamarii and Penicillium citrinum, were isolated. CONCLUSION: Steaming and decaffeination of coffee beans increased antioxidant activities of brews in comparison with those prepared from unprocessed beans. Although toxins can be quantified in green coffee beans and novel fungi were isolated, their concentrations are acceptable according to legal limits. © 2017 Society of Chemical Industry.

Selenium in Gluten-free Products.

The nutritional value of gluten-free products is the subject of interest for food technologists and nutritionists, as the only effective treatment for celiac disease is a lifelong gluten-free diet. As selenium deficiencies in celiac disease are observed, the aim of the study was to determine the selenium content in 27 grain gluten-free products available on the European Union (EU) market. Moreover, selenium content in products based on popular gluten-free cereals like corn, rice, and buckwheat and in relatively new or less popular products based on oat, amaranth, teff, and quinoa was compared. Selenium content in the tested products ranged from 0.9 to 24.5 µg/100 g. The average content of selenium in products based on popular gluten-free cereals was 2.8 µg/100 g and in products based on oat, amaranth, teff, and quinoa was 10.8 µg/100 g. It indicates that products based on less popular grains, especially on oat, should be more frequently chosen as a source of selenium by people on gluten-free diet than traditionally consumed gluten-free grains.

Biodegradation and photo-Fenton degradation of bisphenol A, bisphenol S and fluconazole in water.

Bisphenol A, bisphenol S, and fluconazole are ubiquitous environmental pollutants and their removal from water is of utmost importance. As the biodegradation of these compounds is usually not enough effective, often other degradation methods are required. The study presents the difference between biodegradation and photo-Fenton degradation with a much higher efficiency obtained in the latter process. Levels of biodegradation and chemical degradation were assessed based on high-performance liquid chromatography determination. Optimization of the photo-Fenton removal of bisphenol A, bisphenol S, and fluconazole resulted in about 100 % primary degradation of both bisphenols during 10-20 min and almost 90 % primary degradation of fluconazole within an hour. Degradation products formed in the process were identified using liquid chromatography with mass spectrometry and showed central scission of bisphenol S with the formation of phenol and sulfuric acid while for bisphenol A and fluconazole the oxidation resulted in much smaller structural changes.

Potential health benefits and quality of dried fruits: Goji fruits, cranberries and raisins.

Dried fruits are important snacks and additives to other foods due to their taste and nutritional advantages. Therefore there is an important goal to control the quality of the food on the market for consumer's safety. Antioxidant activity of goji fruits (Lycium barbarum), cranberries (Vaccinium macrocarpon and oxycoccus) and raisins (Vitis vinifera) were studied using the DPPH (2,2-diphenyl-1-picrylhydrazyl) and Folin-Ciocalteu assays. Cu, Mn and Ge influencing antioxidant activity were determined together with selected toxic metals (Cd, Ni and Pb). Contamination with fungi was studied by quantification of their marker - ergosterol and important mycotoxins (aflatoxins B1, B2, G1 and G2, and ochratoxin A) were also determined. Antioxidant activity of all tested dried fruits was confirmed with goji fruits being the most profitable for consumers. Contamination of the tested fruits with toxic metals and mycotoxins was low.

Ultrasound-assisted dispersive micro solid-phase extraction with nano-TiO2 as adsorbent for the determination of mercury species.

The combination of ultrasound-assisted dispersive micro solid-phase extraction (USA DMSPE), with the use of TiO2 nanoparticles (NPs) as adsorbent, with cold vapor atomic absorption spectrometry (CV AAS) is proposed for preconcentration and determination of mercury species (Hgtotal, Hg2+ and CH3Hg+) in biological, geological and water samples. The experimental parameters including the amount of TiO2 NPs, pH of sample solution, ultrasonication and centrifugation time, TiO2 slurry solution preparation before injection to CV AAS were investigated. Effective preconcentration of trace mercury with 10mg of TiO2 was achieved in pH 7.5. After extraction, adsorbent with analytes was mixed with 500µL of 1molL-1 HNO3 to prepare slurry solution. The concentration limit of detection was 0.004ngmL-1 for Hg2+. The achieved preconcentration factor was 35. The relative standard deviations (RSDs, %) for mercury species in real samples were 4-20%. The accuracy of this method was evaluated by analyses of certified reference materials: DOLT-2 (Dogfish Liver), IAEA-085 (Human hair), SRM 2709 (San Joaquin Soil), SRM 2711 (Montana Soil) and SRM 2704 (Buffalo River Sediment). The measured mercury species contents in reference materials were in satisfactory agreement with the added amounts (according to the t-test for a 95% confidence level). The presented method has been successfully applied for the determination of mercury species in real water samples (lake and river water).

Generation of volatile copper species after in situ ionic liquid formation dispersive liquid-liquid microextraction prior to atomic absorption spectrometric detection.

The new procedure using in situ synthesis of ionic liquid extractant for dispersive liquid-liquid microextraction (in situ IL DLLME) combined with generation of volatile species prior to electrothermal atomic absorption spectrometry (ET AAS) for the determination of copper in soil samples was developed. Analytical signals were obtained without the back-extraction of copper from the IL phase prior to its determination. Under optimal conditions, the extraction in 10 mL of sample solution employing 8 µL of 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (HmimNTf2) (as the extraction solvent) was conducted. The ionic liquid served as two-task reagent: the efficient extractant and enhancement substance for generation step. The chemical generation of volatile species was performed by reduction of acidified copper solution (HCl 0.8 mol L(-1)) with NaBH4 (1.5%). Some essential parameters of the chemical generation such as NaBH4 and HCl concentrations, the kind and concentration of ionic liquid, carrier gas (Ar) flow rate, reaction and trapping time as well as pyrolysis and atomization temperatures were studied. For photogeneration the effect of the parameters such as the kind and concentration of low molecular weight organic acids and ionic liquid, carrier gas (Ar) flow rate, UV irradiation and ultrasonication time on the analytical signals were studied. The detection limit was found as 1.8 ng mL(-1) and the relative standard deviation (RSD) for seven replicate measurements of 100 µg mL(-1) in sample solution was 7%. The accuracy of the proposed method was evaluated by analysis of the certified reference materials. The measured copper contents in the reference materials were in satisfactory agreement with the certified values. The method was successfully applied to analysis of the soil and sediment samples.

In situ metathesis ionic liquid formation dispersive liquid-liquid microextraction for copper determination in water samples by electrothermal atomic absorption spectrometry.

In situ synthesis of ionic liquid extractant for dispersive liquid-liquid microextraction (in situ IL DLLME) combined with electrothermal atomic absorption spectrometry (ET AAS) for determination of copper in water samples was developed. Analytical signals were obtained without the back-extraction of copper from the IL phase prior to its determination by AAS. Some essential parameters of the microextraction and detection techniques such as the pH of sample solution, volume of components for in situ synthesis, matrix interferences and main parameters of graphite furnace atomizer have been studied. Under optimal conditions, high extraction efficiency for copper was achieved for the extraction of 0.7 µg L(-1) in 10.0 mL of sample solution employing 8 µL of 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (HmimNTf2) as the extraction solvent. The detection limit was found as 0.004 µg L(-1) with an enrichment factor of 200. The relative standard deviation (RSD) for seven replicate measurements of 0.7 µg L(-1) in sample solution was 4%. The accuracy of the proposed method was evaluated by analysis of the Certified Reference Materials: NIST SRM 2709 (San Joaquin Soil), NBS SRM 2704 (Buffalo River Sediment), NRCC DOLT-2 (Dogfish Liver) and NIST SRM 1643e (Trace Element in Water). The measured copper contents in the reference materials were in satisfactory agreement with the certified values. The method was successfully applied to analysis of the tap, lake and mineral water samples.