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The intricate balance between the beneficial and harmful effects of selenium (Se) intake means that its quantification in food needs to be done correctly. Therefore, in this review, we systematized 105 articles to identify the most studied methodologies, analytical techniques, and food matrices. Among the analytical techniques employed, inductively coupled plasma mass spectrometry (ICP-MS) (n = 29) emerged as the most commonly used method. The most prevalent hydrolysis methodology to digest Se in food matrices involved the use of nitric acid combined with ultrasound, which improved both the yield and digestion time. Optimal recovery values were achieved when total Se quantification accounted for the sum of Se(IV) and Se(VI) (94.4-99.4%) and for SeCys (88-96.5%). These findings are relevant for advancing methodological approaches, and their results emphasize the importance of developing alternative, faster, and lower-cost protocols for Se quantification in foods and beverages.
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Análise de Alimentos , Selênio/química , Bebidas/análise , Limite de DetecçãoRESUMO
Wastewater-based epidemiology has been described as a valuable tool for monitoring the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a community. However, there is no consensus on the best concentration method to allow reliable detection of SARS-CoV-2 in this matrix, considering different laboratory facilities. This study compares two viral concentration methods, ultracentrifugation (ULT) and skimmed-milk flocculation (SMF), for detecting SARS-CoV-2 in wastewater samples. The analytical sensitivity (limits of detection and quantification [LoD/LoQ]) of both methods was evaluated using a bovine respiratory syncytial virus (BRSV) as a surrogate. Three different approaches were conducted to establish LoD of each method based on the assays on the standard curve (ALoDsc), on the dilution of internal control (ALoDiC), and the processing steps (PLoD). For PLoD, ULT method had the lowest value (1.86 × 103 genome copy/microliter [GC/µL]) when compared to the SMF method (1.26 × 107 GC/µL). The LoQ determination showed a mean value of 1.55 × 105 GC/µL and 3.56 × 108 GC/µL to ULT and SMF, respectively. The detection of SARSCoV-2 in naturally contaminated wastewater revealed 100% (12/12) and 25% (3/12) of detection using ULT and SMF with quantification ranging from 5.2 to 7.2 log10 genome copy/liter (GC/L) and 5.06 to 5.46 log10 GC/L, respectively. The detection success rate of BRSV used as an internal control process was 100% (12/12) for ULT and 67% (8/12) for SMF, with an efficiency recovery rate ranging from 12 to 38% and 0.1 to 5%, respectively. Our data consolidates the importance of assessing the methods used; however, further analysis should be carried out to improve low-cost concentration methodologies, essential for use in low-income and developing countries.
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COVID-19 , Vírus , Animais , Bovinos , SARS-CoV-2/genética , COVID-19/diagnóstico , Águas Residuárias , Limite de Detecção , RNA ViralRESUMO
The estimation of limits of detection (LOD) for solely qualitative methods in analytical chemistry may prove challenging because all the approaches with which chemists are familiar require some type of numeric data input. The best model to describe the binary response in these methods (detected/not detected) is a logistic model; however, these models are not easily handled by most of the laboratories and generally demand expensive statistical software packages. In this work, the advantages of applying this approach are discussed and its implementation using commercial spreadsheet software is demonstrated. A free online application based on the R environment using shinyapps was developed and its application was validated and discussed with a dataset of 57 different target compounds analyzed in urine according to the requirements of the World Anti-Doping Agency (WADA). This tool allows free, extremely quick, and easy determinations of LOD in qualitative analyses as well as the determination of the probabilities of detection in any given concentration.
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Dopagem Esportivo , Espectrometria de Massas em Tandem , Limite de Detecção , Espectrometria de Massas em Tandem/métodos , Modelos Logísticos , InternetRESUMO
The present tutorial aims to review the most frequently reported criteria for the calculation of the limits of detection (LOD) and quantification (LOQ) in univariate calibration, summarizing their fundamentals, advantages, and limitations. The current criteria for estimating LOD and LOQ are based on diverse theoretical and/or empirical assumptions and require different amounts of experimental data, making the calculation rather complex in some cases. Moreover, alternative forms for calculating LOD/LOQ frequently lead to dissimilar results. This scenario might worsen in the case of complex analytical systems. Throughout this tutorial, different forms of calculating LOD/LOQ are illustrated using previously reported experimental datasets in the environmental chemistry field as examples. The influence of the sample matrix during the estimation of LOD/LOQ parameters is investigated through one calibration approache. The discrepancies in the obtained results with different criteria for the calculation of LOD/LOQ are highlighted. Finally, general guidelines and recommendations regarding experimental and data processing issues are proposed, aiming to promote fair criteria for the comparison of different analytical methodologies in terms of prediction ability and detection capability.
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Projetos de Pesquisa , Calibragem , Limite de DetecçãoRESUMO
Tuberculosis (TB) is the deadliest infectious caused by Mycobacterium tuberculosis complex (MTBC). Because most TB cases occur within low-income populations, developing a specific, sensitive, cost-saving, and rapid point-of-care test for the early diagnosis of TB is important for achieving the WHO's End Tuberculosis Strategy. In the current study, a novel nucleic acid detection strategy that includes multiplex loop-mediated isothermal amplification combined with a nanoparticle-based lateral flow biosensor (mLAMP-LFB) was used to detect MTBC. The two sets of LAMP primers specific to the IS6110 and gyrB genes of MTBC were successfully designed and validated for the detection of MTBC. The preferred reaction conditions for this assay were confirmed to be 65 °C for 40 min, and the amplification products could be visually identified through LFB within 2 min. The full assay process, including genomic DNA template extraction, LAMP reaction, and product detection, could be completed in 80 min. The limit detection of the assay was 100 fg of DNA in pure culture. The specificity of the assay was 100%, and it had no cross-reactions to other strains. Thus, the m-LAMP-LFB technology established in the present study was an objective, rapid, simple, and sensitive assay for MTBC identification, which could be applied in a clinical setting, especially in resource-constrained regions of the world.
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Técnicas Biossensoriais , Técnicas de Diagnóstico Molecular , Mycobacterium tuberculosis , Técnicas de Amplificação de Ácido Nucleico , Tuberculose , Humanos , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/isolamento & purificação , Nanopartículas , Sensibilidade e Especificidade , Tuberculose/diagnósticoRESUMO
Currently, the detection of pathogens such as Escherichia coli through instrumental alternatives with fast response and excellent sensitivity and selectivity are being studied. Biosensors are systems consisting of nanomaterials and biomolecules that exhibit remarkable properties such as simplicity, portable, affordable, userfriendly, and deliverable to endusers. For this, in this work we report for the first time, to our knowledge, the bioinformatic design of a new peptide based on TIR protein, a receptor of Intimin membrane protein which is characteristic of E. coli. This peptide (named PEPTIR1.0) was used as recognition element in a biosensor based on AuNPsmodified screenprinted electrodes for the detection of E. coli. The morphological and electrochemical characteristics of the biosensor obtained were studied. Results show that the biosensor can detect the bacteria with limits of detection and quantification of 2 and 6 CFU/mL, respectively. Moreover, the selectivity of the system is statistically significant towards the detection of the pathogen in the presence of other microorganisms such as P. aeruginosa and S. aureus. This makes this new PEPTIR1.0 based biosensor can be used in the rapid, sensitive, and selective detection of E. coli in aqueous matrices.
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Técnicas Biossensoriais , Técnicas Eletroquímicas , Escherichia coli O157/química , Proteínas de Escherichia coli/química , Peptídeos/química , Receptores de Superfície Celular/química , Microbiologia da Água , Sequência de Aminoácidos , Biologia Computacional/métodos , Microbiologia de Alimentos , Ouro/química , Ligantes , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Modelos Moleculares , Peptídeos/análise , Conformação Proteica , Sensibilidade e EspecificidadeRESUMO
Foodborne outbreaks caused by parasites have long been a public health issue. Among the available contamination detection methods, qPCR is one of the most sensitive and specific. However, it can be cumbersome and error-prone, if used by unexperienced users. Moreover, qPCR reagents usually require freezer temperatures for transportation and storage. We present a gelified reaction format that allows the reagents to be stored at 2-8⯰C for up to 90â¯days without losing performance. The gelification process eliminates most operator mistakes during reaction setup, and renders the qPCR plates ready-to-use. The new reaction makeup was evaluated using artificially contaminated samples of distinct food matrices for sensitivity, specificity, repeatability, reproducibility, and stability. Samples consisted of cilantro leaves and raspberry fruits spiked with Cyclospora cayetanensis oocysts, as well as açai pulp and sugarcane juice tainted with Trypanosoma cruzi trypomastigotes. No significant difference between the gelified and the non-gelified qPCR was found. Our results suggest that gelifying the assay may help to achieve more reproducible qPCR data across laboratories, thus supporting surveillance actions. (170 words).
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This work aimed to develop cantilever nanobiosensor functionalized with tyrosinase enzyme to detect 17ß-estradiol and estrone hormones. In this system, the tyrosinase enzyme was covalently immobilized by self-assembled monolayer onto the cantilever sensor surface. It was possible to verify that the high hormone concentration investigated resulted in high voltage response. The nanobiosensor presented a distinction between the concentrations evaluated and was verified sensitivities of 0.497 and 0.101 V/µg, limit of detection of 0.1 and 0.4 ng/L for the hormones 17ß-estradiol and estrone, respectively. The device showed good reversibility and during 30 days of storage maintained about 99% of the original signal. The cantilever nanobiosensor applied in different water samples (ultrapure, river, tap, and mineral) showed good performance, so could be readily extended toward the on-site monitoring of the other trace small molecular pollutants in environmental water matrices.
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Técnicas Biossensoriais , Monitoramento Ambiental/instrumentação , Monitoramento Ambiental/métodos , Estradiol/análise , Estrona/análise , Monofenol Mono-Oxigenase/química , Nanopartículas/química , Poluentes Químicos da Água/análise , Poluentes Ambientais/análise , Limite de Detecção , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Nanotecnologia , Rios , Silício/química , Esteroides , Propriedades de Superfície , Água/químicaRESUMO
BACKGROUND: The loss of large amounts of blood postpartum can lead to severe maternal morbidity and mortality. Understanding the nature of postpartum blood loss distribution is critical for the development of efficient analysis techniques when comparing treatments to prevent this event. When blood loss is measured, resulting in a continuous volume measure, often this variable is categorized in classes, and reduced to an indicator of volume greater than a cutoff point. This reduction of volume to classes entails a substantial loss of information. As a consequence, very large trials are needed to assess clinically important differences between treatments to prevent postpartum haemorrhage. METHODS: The authors explore the nature of postpartum blood loss distribution, assuming that the physical properties of blood loss lead to a lognormal distribution. Data from four clinical trials and one observational study are used to confirm this empirically. Estimates of probabilities of postpartum haemorrhage events 'blood loss greater than a cutoff point' and relative risks are obtained from the fitted lognormal distributions. Confidence intervals for relative risk are obtained by bootstrap techniques. RESULTS: A variant of the lognormal distribution, the three-parameter lognormal distribution, showed an excellent fit to postpartum blood loss data of the four trials and the observational study. A measurement quality assessment showed that problems of digit preference and lower limit of detection were well handled by the lognormal fit. The analysis of postpartum haemorrhage events based on a lognormal distribution improved the efficiency of the estimates. Sample size calculation for a hypothetical future trial showed that the application of this procedure permits a reduction of sample size for treatment comparison. CONCLUSION: A variant of the lognormal distribution fitted very well postpartum blood loss data from different geographical areas, suggesting that the lognormal distribution might fit postpartum blood loss universally. An approach of analysis of postpartum haemorrhage events based on the lognormal distribution improves efficiency of estimates of probabilities and relative risk, and permits a reduction of sample size for treatment comparison. TRIAL REGISTRATION: This paper reports secondary analyses for trials registered at Australian New Zealand Clinical Trials Registry (ACTRN 12608000434392 and ACTRN12614000870651); and at clinicaltrials.gov (NCT00781066).
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Ensaios Clínicos como Assunto , Modelos Teóricos , Hemorragia Pós-Parto/prevenção & controle , Feminino , Humanos , Período Pós-Parto , Gravidez , Índice de Gravidade de DoençaRESUMO
Mixed infections with Trypanosoma cruzi and Trypanosoma rangeli and their different genetic groups occur frequently in vertebrate hosts and are difficult to detect by serology. In the present study, we evaluated the limit of detection of polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) analysis of cytochrome oxidase II (COII) for the identification of genetic groups of these two parasites in blood and tissue from vertebrate hosts. Reconstitution experiments were performed using human blood (TcI/TcII and KP1+/KP1-) and mouse tissue (TcI/TcII). We tested blood from patients who were in the chronic phase of Chagas disease and tissue from animals that were experimentally infected with all possible combinations of six discrete typing units. In blood samples, T. cruzi and T. rangeli were detected when 5 parasites (pa) were present in the sample, and genetic groups were identified when at least 50 pa were present in the sample. T. cruzi alone could be detected with 1 pa and genotyped (TcI/TcII) with 2 pa. T. rangeli was detected with 2 pa and genotyped (KP+/KP1-) with 25 pa. The present method more readily detected TcII and KP1- in both admixtures and alone. In mouse tissue, TcI and TcII were detected with at least 25 pa. The analysis of blood samples from patients and tissue from animals that were experimentally infected revealed low parasite loads in these hosts, which were below the limit of detection of the present method and could not be genotyped. Our findings indicate that the performance of PCR/RFLP analysis of COII is directly related to the amount and proportion of parasites that are present in the sample and the genetic groups to which the parasites belong.
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Doença de Chagas/parasitologia , Doença de Chagas/veterinária , Complexo IV da Cadeia de Transporte de Elétrons/genética , Reação em Cadeia da Polimerase/métodos , Polimorfismo de Fragmento de Restrição , Proteínas de Protozoários/genética , Trypanosoma cruzi/isolamento & purificação , Trypanosoma rangeli/isolamento & purificação , Animais , Genótipo , Humanos , Limite de Detecção , Camundongos , Doenças dos Roedores/parasitologia , Trypanosoma cruzi/enzimologia , Trypanosoma cruzi/genética , Trypanosoma rangeli/enzimologia , Trypanosoma rangeli/genéticaRESUMO
The authors report on a loop-mediated isothermal amplification (LAMP) scheme that uses antarctic thermally sensitive uracil-DNA-glycosylase (AUDG) for simultaneous detection of nucleic acids and elimination of carryover contamination. It was applied in a lateral flow assay (LFA) format. The assay has attractive features in that it does not require the use of labeled primers or probes, and can eliminate false-positive results generated by unwanted hybridization between two labeled primers or between a labeled primer and probe. LAMP amplification and AUDG digestion are conducted in a single pot, and the application of a closed-tube reaction prevents false-positives due to carryover contamination. The method was applied to the detection of the human pathogen Streptococcus pneumoniaein in pure cultures and spiked blood samples. This LFA can detect S. pneumoniae in pure cultures with a 25 fg.µL-1 detection limit and in spiked blood samples with a 470 cfu.mL-1 detection limit. Conceivably, this assay can be applied to the detection of various other targets if the specific LAMP primers are available. Graphical abstract á .
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Técnicas Biossensoriais/métodos , DNA Bacteriano/análise , Técnicas de Amplificação de Ácido Nucleico/métodos , Streptococcus pneumoniae/genética , Streptococcus pneumoniae/isolamento & purificação , Temperatura , Uracila-DNA Glicosidase/metabolismo , DNA Bacteriano/genética , HumanosRESUMO
Spatially-referenced geostatistical responses that are collected in environmental sciences research are often subject to detection limits, where the measures are not fully quantifiable. This leads to censoring (left, right, interval, etc), and various ad hoc statistical methods (such as choosing arbitrary detection limits, or data augmentation) are routinely employed during subsequent statistical analysis for inference and prediction. However, inference may be imprecise and sensitive to the assumptions and approximations involved in those arbitrary choices. To circumvent this, we propose an exact maximum likelihood estimation framework of the fixed effects and variance components and related prediction via a novel application of the Stochastic Approximation of the Expectation Maximization (SAEM) algorithm, allowing for easy and elegant estimation of model parameters under censoring. Both simulation studies and application to a real dataset on arsenic concentration collected by the Michigan Department of Environmental Quality demonstrate the advantages of our method over the available naïve techniques in terms of finite sample properties of the estimates, prediction, and robustness. The proposed methods can be implemented using the R package CensSpatial.
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Neutering is a common veterinary recommendation and is often associated with obesity development. Thus, the aim of the present study was to evaluate the effects of two different amounts of protein intake by neutered dogs regarding maintenance energy requirement (MER), body composition, and biochemical and hormonal parameters. A total of fourteen healthy adult dogs were fed either a diet containing 59·7 g protein/1000 kcal (4184 kJ) (P60) or a diet with 94·0 g protein/1000 kcal (4184 kJ) (P94) for 26 weeks after neutering to maintain their body weight prior to neutering. A mixed model was fitted to verify diet, time and diet × time interaction effects on biochemical parameters, serum concentrations of insulin, glucagon, leptin and insulin-like growth factor-1 (IGF-1). MER and the body composition data were evaluated within diets (paired t test) and within times (unpaired t test). A time effect was found for fructosamine, TAG, total lipids and IGF-1 serum concentrations. The diet × time interaction was significant for glucagon (P < 0·05). No differences between diets in the MER within each time were found. However, there was a reduction in the MER of dogs fed the P60 diet 26 weeks after neutering (P = 0·042). The fat body mass of dogs fed the P60 diet increased (P < 0·05) after neutering, even without a body-weight change. Some of the biochemical parameters changed over time, but all remained within the normal range. For the period evaluated in the present study, a diet with 94·0 g of protein/1000 kcal (4184 kJ) metabolisable energy seems to be a beneficial nutritional strategy to maintain the MER and the body composition of dogs after neutering.
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Vibrio cholerae is an important human pathogen that is responsible for cholera, a severe acute watery diarrhea. In the current study, a multiple cross displacement amplification (MCDA) coupled with amplicon detection by chromatographic lateral flow biosensor (LFB) method (MCDA-LFB) was successfully established and evaluated for the identification of V. cholerae. A set of 10 primers was designed specifically to recognize 10 different regions of the V. cholerae-specific gene ompW. The optimized time and temperature conditions for the MCDA were 30 min and 63°C, respectively. The MCDA-LFB assay correctly identified 31 strains of V. cholerae but did not detect 13 non-cholerae Vibrio strains and 30 non-Vibrio strains. The sensitivity of MCDA-LFB for target pathogen detection in pure culture was 10 fg per reaction. In the case of spiked shrimp samples without enrichment, the limit of detection was 4.1 CFUs per reaction or equivalent to 4.1 × 102 CFU g-1. The whole process, including shrimp homogenates processing (30 min), MCDA reaction (30 min) and results reporting (2 min), could be finished within 65 min. These results show that this assay is suitable for the rapid, sensitive and specific detection of V. cholerae in food, environmental and clinical samples.
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Técnicas Biossensoriais/instrumentação , Nanopartículas/química , Técnicas de Amplificação de Ácido Nucleico/métodos , Vibrio cholerae/genética , Animais , Proteínas da Membrana Bacteriana Externa/genética , Desenho de Equipamento , Microbiologia de Alimentos , Limite de Detecção , Técnicas de Amplificação de Ácido Nucleico/instrumentação , Penaeidae/microbiologiaRESUMO
BACKGROUND: Rapid diagnostic test (RDT) positivity is supplanting microscopy as the standard measure of malaria burden at the population level. However, there is currently no standard for externally validating RDT results from field surveys. METHODS: Individuals' blood concentration of the Plasmodium falciparum histidine rich protein 2 (HRP2) protein were compared to results of HRP2-detecting RDTs in participants from field surveys in Angola, Mozambique, Haiti, and Senegal. A logistic regression model was used to estimate the HRP2 concentrations corresponding to the 50 and 90% level of detection (LOD) specific for each survey. RESULTS: There was a sigmoidal dose-response relationship between HRP2 concentration and RDT positivity for all surveys. Variation was noted in estimates for field RDT sensitivity, with the 50% LOD ranging between 0.076 and 6.1 ng/mL and the 90% LOD ranging between 1.1 and 53 ng/mL. Surveys conducted in two different provinces of Angola using the same brand of RDT and same study methodology showed a threefold difference in LOD. CONCLUSIONS: Measures of malaria prevalence estimated using population RDT positivity should be interpreted in the context of potentially large variation in RDT LODs between, and even within, surveys. Surveys based on RDT positivity would benefit from external validation of field RDT results by comparing RDT positivity and antigen concentration.
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Antígenos de Protozoários/análise , Testes Diagnósticos de Rotina/métodos , Malária Falciparum/diagnóstico , Plasmodium falciparum/isolamento & purificação , Proteínas de Protozoários/análise , Adolescente , Adulto , África Subsaariana/epidemiologia , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Feminino , Haiti/epidemiologia , Humanos , Lactente , Malária Falciparum/epidemiologia , Malária Falciparum/parasitologia , Masculino , Pessoa de Meia-Idade , Prevalência , Sensibilidade e Especificidade , Adulto JovemRESUMO
The glutathione S-transferase (GST)-L1 multiplex serology assay has favorable properties for use in clinical trials and epidemiologic studies, including low cost, high throughput capacity, and low serum volume requirement. Therefore, we evaluated the GST-L1 assay as a measure of HPV16/18 vaccine immunogenicity. Our study population included 65 women selected from the Costa Rica Vaccine Trial who received the bivalent HPV16/18 virus-like particle (VLP) vaccine at the recommended 0/1/6-month schedule. We tested replicate serum samples from months 0/1/12 (i.e., after 0/1/3 doses) by GST-L1 and 3 other commonly used serology assays, VLP-ELISA, SEAP-NA, and cLIA. We calculated the percentage of women seropositive by GST-L1 by time point and HPV type (14 HPV types), and compared GST-L1 to other assays using Spearman rank correlation coefficients. After 1 vaccine dose, seropositivity by GST-L1 was 40% each for HPV16 and HPV18, increasing to 100% and 98%, respectively, after 3 doses. Seropositivity after 3 doses ranged from 32% to 69% for HPV types 31/33/45, for which partial vaccine efficacy is reported, though increases also occurred for types with no evidence for cross-protection (e.g., HPV77). GST-L1 correlated best after 3 doses with VLP-ELISA (HPV16 and HPV18 each ρ = 0.72) and SEAP-NA (HPV16 ρ = 0.65, HPV18 ρ = 0.71) (all P < 0.001); correlation was lower with cLIA. The GST-L1 is suitable for evaluating HPV16/18 vaccine immunogenicity after 3 vaccine doses, although in contrast to other assays it may classify some samples as HPV16/18 seronegative. The assay's utility is limited for lower antibody levels such as after receipt of 1 dose.
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Bioensaio/métodos , Papillomavirus Humano 16/imunologia , Papillomavirus Humano 18/imunologia , Infecções por Papillomavirus/imunologia , Vacinas contra Papillomavirus/imunologia , Anticorpos Neutralizantes/sangue , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Formação de Anticorpos/imunologia , Costa Rica , Proteção Cruzada , Feminino , Glutationa Transferase/metabolismo , Humanos , Imunização Secundária , Infecções por Papillomavirus/prevenção & controle , Reprodutibilidade dos Testes , VacinaçãoRESUMO
In this work, a novel molecularly imprinted polymer (MIP) for use as a solid phase extraction sorbent was developed for the determination of coenzyme Q10 (CoQ10) in liver extract. CoQ10 is an essential cofactor in mitochondrial oxidative phosphorylation and a powerful antioxidant agent found in low concentrations in biological samples. This fact and its high hydrophobicity make the analysis of CoQ10 technically challenging. Accordingly, a MIP was synthesised using coenzyme Q0 as the template, methacrylic acid as the functional monomer, acetonitrile as the porogen, ethylene glycol dimethacrylate as the crosslinker and benzoyl peroxide as the initiator. Various parameters affecting the polymer preparation and extraction efficiency were evaluated. Morphological characterisation of the MIP and its proper comparison with C18 as a sorbent in solid phase extraction were performed. The optimal conditions for the molecularly imprinted solid phase extraction (MISPE) consisted of 400 µL of sample mixed with 30 mg of MIP and 600 µL of water to reach the optimum solution loading. The loading was followed by a washing step consisting of 1 mL of a 1-propanol solution (1-propanol:water, 30:70,v/v) and elution with 1 mL of 1-propanol. After clean-up, the CoQ10 in the samples was analysed by high performance liquid chromatography. The extraction recoveries were higher than 73.7% with good precision (3.6-8.3%). The limits of detection and quantification were 2.4 and 7.5 µg g(-1), respectively, and a linear range between 7.5 and 150 µg g(-1) of tissue was achieved. The new MISPE procedure provided a successful clean-up for the determination of CoQ10 in a complex matrix.
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Benzoquinonas/química , Impressão Molecular , Polímeros/química , Espectrofotometria Ultravioleta , Ubiquinona/análogos & derivados , Benzoquinonas/metabolismo , Cromatografia Líquida de Alta Pressão , Extração em Fase Sólida , Solventes/química , Ubiquinona/análise , Ubiquinona/isolamento & purificação , Ubiquinona/metabolismoRESUMO
Prenatal lead exposure is a health hazard that may cause cognitive development impairments and other adverse effects in children. We conducted a cross sectional study analyzing cord blood lead levels (CBLL) of newborns and their relationship with maternal determinants of lead exposure. Mothers answered a questionnaire about socio-demographic, lifestyle habits and environmental characteristics. We used Mann-Whitney's test to compare CBLL geometrical means (GM) corresponding to the presence or absence of each lead exposure determinant, and Chi square test to study the relationship between CBLL and maternal lead exposure determinants. A total of 159 newborns participated in the study. CBLL GM was 2.1 µg/dL; and 25% of the participants had a measurable CBLL (LOQ=3.3 µg/dl). Although the participants had several determinants of lead exposure, we only found a significant relationship with inside household determinants, such as presence of lead piping (p=0.026), unplastered walls (p=0.046) and peeling paint (p=0.048). Our results show that CBLL GM was similar to that reported in several studies conducted around the world. However, 25% of the participants might have some degree of risk for lead poisoning.
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Poluentes Ambientais/sangue , Chumbo/sangue , Exposição Materna/estatística & dados numéricos , Adulto , Argentina/epidemiologia , Feminino , Maternidades , Habitação/estatística & dados numéricos , Humanos , Recém-Nascido , Intoxicação por Chumbo/epidemiologia , Masculino , GravidezRESUMO
Solid phase microextraction (SPME) is a fast, cheap and solvent free methodology widely used for environmental analysis. A SPME methodology has been optimized for the analysis of VOCs in a range of matrices covering different soils of varying textures, organic matrices from manures and composts from different origins, and biochars. The performance of the technique was compared for the different matrices spiked with a multicomponent VOC mixture, selected to cover different VOC groups of environmental relevance (ketone, terpene, alcohol, aliphatic hydrocarbons and alkylbenzenes). VOC recovery was dependent on the nature itself of the VOC and the matrix characteristics. The SPME analysis of non-polar compounds, such as alkylbenzenes, terpenes and aliphatic hydrocarbons, was markedly affected by the type of matrix as a consequence of the competition for the adsorption sites in the SPME fiber. These non-polar compounds were strongly retained in the biochar surfaces limiting the use of SPME for this type of matrices. However, this adsorption capacity was not evident when biochar had undergone a weathering/aging process through composting. Polar compounds (alcohol and ketone) showed a similar behavior in all matrices, as a consequence of the hydrophilic characteristics, affected by water content in the matrix. SPME showed a good performance for soils and organic matrices especially for non-polar compounds, achieving a limit of detection (LD) and limit of quantification (LQ) of 0.02 and 0.03 ng g(-1) for non-polar compounds and poor extraction for more hydrophilic and polar compounds (LD and LQ higher 310 and 490 ng g(-1)). The characteristics of the matrix, especially pH and organic matter, had a marked impact on SPME, due to the competition of the analytes for active sites in the fiber, but VOC biodegradation should not be discarded in matrices with active microbial biomass.
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Monitoramento Ambiental/métodos , Poluentes Ambientais/análise , Microextração em Fase Sólida/métodos , Compostos Orgânicos Voláteis/análise , Poluentes Ambientais/química , Compostos Orgânicos Voláteis/químicaRESUMO
Arsenic is an element widely present in nature. Additionally, it may be found as different species in several matrices and therefore it is one of the target elements in chemical speciation. Although the number of studies in terrestrial plants is low, compared to matrices such as fish or urine, this number is raising due to the fact that this type of matrix are closely related to the human food chain. In speciation analysis, sample preparation is a critical step and several extraction procedures present drawbacks. In this review, papers dealing with extraction procedures, analytical methods, and studies of species conservation in plants cultivated in terrestrial environment are critically discussed. Analytical procedures based on extractions using water or diluted acid solutions associated with HPLC-ICP-MS are good alternatives, owing to their versatility and sensitivity, even though less expensive strategies are shown as feasible choices.