Control of predators in industrial scale microalgae cultures with Pulsed Electric Fields.

This work describes the utilization of Pulsed Electric Fields to control the protozoan contamination of a microalgae culture, in an industrial 2.7 m(3) microalgae photobioreactor. The contaminated culture was treated with Pulsed Electric Fields, PEF, for 6h with an average of 900 V/cm, 65 µs pulses of 50 Hz. Working with recirculation, all the culture was uniformly exposed to the PEF throughout the assay. The development of the microalgae and protozoan populations was followed and the results showed that PEF is effective on the selective elimination of protozoa from microalgae cultures, inflicting on the protozoa growth halt, death or cell rupture, without affecting microalgae productivity. Specifically, the results show a reduction of the active protozoan population of 87% after 6h treatment and 100% after few days of normal cultivation regime. At the same time, microalgae growth rate remained unaffected.

Rapid determination of piperazine-type stimulants in human urine by microextraction in packed sorbent after method optimization using a multivariate approach.

This paper describes the analysis of piperazine-type stimulants [1-benzylpiperazine (BZP), 1-(3-trifluoromethylphenyl)piperazine (TFMPP), 1-(3-chlorophenyl)piperazine (mCPP) and 1-(4-methoxyphenyl)piperazine (MeOPP)] in low volume urine samples (0.1 mL) by microextraction in packed sorbent and liquid chromatography-diode array detection. Analyte extraction has been comprehensively optimized, and the influencing factors were screened by means of the fractional factorial design approach. Several parameters susceptible of influencing the process were studied, and these included extraction sorbent type (C(8) and C(18)), sample dilution (1:2 and 1:4), number of aspirations through the device (2 and 8) and the amount of methanol on both the washing (0 and 10%) and eluting solvents (10 and 100%). The method was linear from 0.5 (lower limit of quantitation) to 5 µgmL(-1), with determination coefficients higher than 0.99 for all compounds. Intra- and interday precision ranged from 1 to 9%, trueness was within a ± 11% interval for all analytes, and analyte recoveries were of about 70% for mCPP and TFMPP, and of about 10% for MeOPP and BZP. The method has shown to be selective, as no interferences from endogenous substances were detected by analysis of blank samples, and the analytes were stable in the samples for short periods at room temperature, after three freeze/thaw cycles and in processed samples. Due to its simplicity and speed, this method can be successfully applied in the screening and quantitation of these compounds in urine samples, and is suitable for application in forensic toxicology routine analysis.

Ultrasonic energy as a tool to overcome some drawbacks in the determination of lead in brain tissue and urine of rats.

An ultrasonic assisted solid-liquid extraction method was developed to determine the level of lead in the brain and urine of rats. Lead was determined by electrothermal atomic absorption spectrometry with longitudinal-Zeeman background correction. Several analytical drawbacks were addressed and overcome, namely small brain sample mass and the formation of precipitate in the urine samples. Utrasonication provided by an ultrasonic probe succeeded in extracting lead from brain samples. Furthermore, it was demonstrated that the formation of a precipitate lowered the lead content in the liquid phase of the urine. Lead was back extracted from the precipitate to the liquid phase with the aid of ultrasonic energy and acidifying the urine with 10% v/v nitric acid. A microwave-assisted acid digestion protocol was used to check the completeness of the lead extraction. The within bath and between bath precision was 5% (n=9) and 7% (n=3) respectively. The limit of quantification was 1.05 µg g(-1) for brain samples and 2.1 µg L(-1) for urine samples. A total of 6 samples of urine and 12 samples of brain from control rats and another 6 samples of urine and 12 samples of brain from rats fed with tap water rich in lead acetate were used in this research. Lead levels in brain and urine from exposed rats ranged from 1.9 ± 0.2 µg g(-1) to 3.5 ± 0.2 µg g(-1) and from 752 ± 56 µg L(-1) to 60.9 ± 1.2 mg L(-1) respectively. Statistically significant differences of levels of lead in brain and urine were found between exposed and non exposed rats.

Ethics issues experienced in HBM within Portuguese health surveillance and research projects.

BACKGROUND: In keeping with the fundamental practice of transparency in the discussion and resolution of ethics conflicts raised by research, a summary of ethics issues raised during Portuguese biomonitoring in health surveillance and research is presented and, where applicable, their resolution is described. METHODS: Projects underway aim to promote the surveillance of public health related to the presence of solid waste incinerators or to study associations between human exposure to environmental factors and adverse health effects. The methodological approach involves biomonitoring of heavy metals, dioxins and/or other persistent organic pollutants in tissues including blood, human milk and both scalp and pubic hair in groups such as the general population, children, pregnant women or women attempting pregnancy. As such, the projects entail the recruitment of individuals representing different demographic and health conditions, the collection of body tissues and personal data, and the processing of the data and results. RESULTS: The issue of autonomy is raised during the recruitment of participants and during the collection of samples and data. This right is protected by the requirement for prior written, informed consent from the participant or, in the case of children, from their guardian. Recruitment has been successful, among eligible participants, in spite of incentives rarely being offered. The exception has been in obtaining guardians' consent for children's participation, particularly for blood sampling. In an attempt to mitigate the harm-benefit ratio, current research efforts include alternative less invasive biomarkers.Surveys are currently being conducted under contract as independent biomonitoring actions and as such, must be explicitly disclosed as a potential conflict of interests. Communication of results to participants is in general only practised when a health issue is present and corrective action possible. Concerning human milk a careful approach is taken, considering breast-feeding's proven benefits. CONCLUSION: No national legislation currently accounts for the surveillance component of biomonitoring as distinct from research. Ethics issues arising within the domain of research are resolved according to available regulations. For issues encountered during surveillance, the same principles are used as guidance, completed by the authors' best judgement and relevant ethics committees' findings.

Reduction of wastewaters and valorisation of by-products from "Serpa" cheese manufacture using nanofiltration.

Second cheese whey (SCW) is a by-product of cheese and curd cheese production that is usually not recovered and therefore contributes substantially to the negative environmental impact of the cheese manufacture plants. Membrane technology, namely nanofiltration (NF), is used in this work for the recovery of SCW organic nutrients, resulting from "Serpa" cheese and curd production. The SCW is processed by NF to recover a rich lactose fraction in the concentrate and a process water with a high salt content in the permeate. The permeation experiments were carried out in a plate and frame NF unit, where two NF membranes (NFT50 and HR-95-PP) were characterized and tested. The NF permeation experiments were performed accordingly with two different operation modes: total recirculation and concentration. In order to select the best membrane and operating pressure for the SCW fractionation, total recirculation experiments were carried out. After the membrane selection, the concentration experiments showed that the selected membrane (NFT50) at 30 bar allows a water recovery of approximately 80%, concentrating the second cheese whey nutrients approximately 5 times. Therefore, the NF operation can successfully reduce the wastewater organic load and simultaneously contribute to the valorisation of the cheese and curd cheese manufacture by-products.