Phytoremediation potential of Ulva ohnoi (Chlorophyta): Influence of temperature and salinity on the uptake efficiency and toxicity of cadmium.

Ulva ohnoi is a green macroalga with fast growth and high rates of nitrogen and phosphorus absorption. Recently, this species has been recorded in several places with record green tide formation in some of them. Using molecular tools, we herein report the first occurrence of this species in Brazil and demonstrate its potential for phytoremediation in typical environmental concentrations of Cd (0.625-15 µg L-1). Similarly, the effects of physicochemical parameters (salinity and temperature) on the toxicity and uptake efficiency of this species were evaluated. Molecular analysis of two sequences (1141 bp) obtained corroborates another 34 sequences for U. ohnoi obtained from GenBank. The addition of Cd in the medium affected photosynthetic parameters and reduced growth rate. U. ohnoi showed resistance to Cd when cultivated at 18 °C, S15 and 18-25 °C, S35, at concentrations between 0.625 and 2.5 µg. L-1 of Cd; yet, positive growth rate was maintained. Dose-dependent accumulation was observed in all combinations of factors used with a maximum value of 4.20 µg Cd per gram of dry seaweed at 15 µg. L-1 of Cd at 18 °C and S35. Maximum value of the concentration factor was 81.3 ±â€¯1.1% of Cd added at the concentration of 0.625 µg. L-1 to S15 and 18 °C. Our results demonstrate the potential of using U. ohnoi in the phytoremediation of Cd in saltwater or brackish water.

Determination of hormones in urine by hollow fiber microporous membrane liquid-liquid extraction associated with 96-well plate system and HPLC-FLD detection.

In this work, hollow-fiber microporous membrane liquid-liquid extraction (HF-MMLLE) was associated with a 96-well plate system for the determination of estrone, 17-ß-estradiol, estriol and 17-α-ethinylestradiol in urine samples. This method exhibited some advantages, such as low cost, easy application, high-throughput and environmentally-friendly aspects. The type of organic solvent to fill the membrane, ionic strength effect, sample dilution, extraction and desorption time, and desorption solvent were examined. After the optimizations, the conditions were comprised of 45 min of extraction, 1-octanol as organic solvent and 15% (w/v) of NaCl; methanol was used as desorption solvent, and the desorption time was fixed at 10 min. The dilution of the sample increased the sensitivity due to the reduction of matrix effects; thus, urine samples were diluted 40-fold. The limits of detection ranged from 0.03 µg L-1 for 17-ß-estradiol to 15 µg L-1 for estrone, and the limits of quantification ranged from 0.1 µg L-1 for 17-ß-estradiol to 10 µg L-1 for estrone. The intra-day precision varied from 1.0% for estriol to 13.3% for 17-α-ethinylestradiol, and inter-day precision varied from 7.3% for estrone to 18.1% for estriol. The relative recoveries varied from 82 to 118%.

The use of microwave-induced plasma optical emission spectrometry for fluorine determination and its application to tea infusions.

This study presents a novel method for fluorine quantification determination by microwave-induced plasma optical emission spectrometry (MIP-OES). Due to the low temperature of this plasma, atomic emission of fluorine could not be measured, instead CaF molecular emissions were measured by using a calcium solution mixed in the spray chamber with the sample using a T-piece. Several wavelengths were studied to find the best signal to noise ratio for fluorine determination and 530.45 nm was chosen. The limit of detection for the determination of fluorine via CaF using MIP-OES was 1.1 mg L-1. A linear response was observed over two orders of magnitude (R2 = 0.998). The developed method was applied to ten tea infusion samples from the UK and Saudi Arabia. The results were not significantly different (paired Student's t-test, p = 0.97) to the results obtained using the reference method, high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-GF MAS). The total fluorine in the tea infusions varied between 2.7 and 7.8 mg L-1; all of which were above the WHO recommended level of fluoride (0.8-1.5 mg L-1) in drinking water. This method can potentially be used for total fluorine determination and might be useful for fluorine speciation analysis when coupled with HPLC.

The use of high resolution graphite furnace molecular absorption spectrometry (HR -MAS) for total fluorine determination in extractable organofluorines (EOF).

The determination of total fluorine content using high-resolution graphite furnace continuum source molecular absorption spectrometry (HR- MAS) has been employed in a variety of samples for over 10 years. However, most of the samples analysed by HR- MAS are rich in fluoride, with negligible levels of organic fluorinated species. With an increase in concern surrounding per- and polyfluoroalkyl substances (PFASs), new methods to measure total fluorine of organofluorine using different techniques have been developed. However, no studies focused on PFASs behaviour in HR-MAS have been performed. As these compounds encompass a wide range of different structures, boiling points, decomposition temperatures and matrix interactions, a loss of accuracy can occur when an aqueous external calibration is performed using only one compound. To overcome this issue, an investigation into permanent modifiers for the graphite furnace was performed. After optimisation similar sensitivity for different PFCA was achieved when 400 µg of W was used as a permanent modifier together with an optimised temperature program. The relative deviation between the different PFCA standard slopes relative to the PFOA slope was lower than 15%. The instrumental limit of detection and quantification (LOD and LOQ, respectively) of total fluorine as total PFCA was 0.1 mg L-1 and 0.3 mg L-1, respectively, while the method LOD and LOQ (using solid phase extraction) was 0.3 µg L-1 and 1.0 µg L-1, respectively. The developed method gave satisfactory recoveries for the spiked PFCA into seawater, river water and effluent using PFOA calibration standards. The optimised method is useful for measuring extractable organofluorines (EOF) when only ionic PFASs such as PFCA are expected. When other organofluorines are expected, the results using HR GF-MAS should be taken with caution.

Determination of arsenic in agricultural soil samples using High-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample analysis.

Soils around coal-fired thermal power plants based on coal combustion can present high concentrations of arsenic. This fact has a direct effect on the food chain. Arsenic can be absorbed by plants and vegetables through the soil, which will then serve as food for different animals, spreading the contamination. A method has been developed using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) for direct determination of arsenic in solid soil samples. Different chemical modifiers were tested to suppress the matrix effects observed. Among them, the modifier that showed the best results was the Zr, used as a permanent modifier. The optimized pyrolysis and atomization temperatures were 1000 °C and 2200 °C, respectively. A calibration curve was established using aqueous standard solutions which was linear up to 16 ng of arsenic. The characteristic mass and limit of detection were 22 pg and 73 pg As, respectively. The accuracy of the method was verified using two certified reference materials and comparison with results obtained for samples after microwave-assisted digestion. Eleven soil samples were collected around the power plant Complex Jorge Lacerda-Tractebel Suezin, in the south of Santa Catarina, Brazil. The concentration of As ranged from 3.4 mg kg-1 to 9.7 mg kg-1, which is within the limits allowed by Brazilian legislation.