Avaliação das condições de precipitação do azul da Prússia sobre pó de grafite visando o desenvolvimento de eletrodos de pasta de carbono para a quantificação de nitrito

An amperometric FIA method for nitrite quantification based on nitrite electroreduction and employing a carbon paste electrode (CPE) chemically modified with iron hexacyanoferrate (HCF) as an amperometric detector was developed. The influence of experimental conditions on the preparation of the electrode materials was evaluated and the materials obtained in each study were used for the development of modified electrodes. The electrochemical sensors were prepared by a fast, simple, and inexpensive procedure, and the long-term performance of the electrodes were quite satisfactory as the stability was maintained over one year. HCF was an effective redox mediator for nitrite electroreduction in acidic media, allowing nitrite detection at +0.2 V vs. Ag/AgClsat, which is a potential free of possible interfering species that are normally present in food and water samples. The electrochemical cell used in the FIA system was similar to a batch injection analysis cell, enabling recirculation of the carrier solution. This is an attractive feature because it allows the use of a high flow rate (6 mL min-1) leading to high sensitivity and analysis speed, while keeping reagent consumption low. The proposed method had a detection limit of 9 μmol L-1 and was successfully employed for nitrite quantification in spiked water and sausage samples. The obtained results were in good agreement with those provided by the spectrophotometric official method. At a 95 % confidence level it was not observed statistical differences neither in nitrite content nor in the precision provided by both methods. The experimental conditions for the synthesis of HCF were optimized and the best electrode material was prepared by mixing FeCl3, K4[Fe(CN)6] and carbon powder subjected to an acid and thermal treatment (400 ºC), followed by ultrasonic agitation at 4 °C. This material was used to construct an electrode with improved analytical performance to reduce nitrite, which presented greater stability compared to HCF film electrodeposited on the EPC, showing that the preparation procedure of the electrode material is an effective strategy for the development of HCF modified electrodes.

Relação entre a cárie precoce da infância com o índice de Apgar e outros fatores de risco

The aim of this cross-sectional study was to investigate the association of early childhood caries (ECC) with the Apgar score (AS) and other variables related to the child (conditions at birth and medical history) and related to the child and parents and / or guardians and family (demographic, socioeconomic and behavioral). One hundred and twenty healthy children aged between 3-5 years-old treated by Pediatric Dentistry Area of Dentistry College of the Federal University of Uberlandia during 2015 were selected. To obtain qualitative and quantitative variables a questionnaire was applied as an interview to the parents and/or guardians. The 5-minute AS (interest exposure) was obtained through the record in the Child Health Handbook. To assess the prevalence of caries (clinical dependent variable), a single calibrated researcher conducted the clinical examination, according to the criteria of the World Health Organization. Caries experience was measured using the indexes dmft and dmfs. The children were classified into three groups, according to age and dmfs index: no caries (NC), with ECC and with severe early childhood caries (S-ECC). Data were tabulated and submitted to statistical analysis using the SPSS software (IBM, Inc, Chicago, Illinois, USA) 17th version. Three logistics models were carried out having the following classifications: NC and ECC, NC and S-ECC, ECC and S-ECC (p<0.05). The overall ECC prevalence, considering children with ECC and S-ECC, was 55,8% (n= 67). The AS was not a statistically significant variable. The child’s age, weaning age and recent hospitalization were variables associated with the ECC prevalence. The age of brush start and the educational level of the mother were variables associated with the S-ECC prevalence. Considering the ECC and the S-ECC groups, the child's age and the beginning of the use of fluoride toothpaste, recent hospitalization, the educational level of the mother and the father's income were associated with the S-ECC prevalence. Considering the methodology employed and the analysis of results, it was concluded that there was no association between the ECC with the AS in healthy children. However, an association was found of ECC and S-ECC with some variables related to birth and to medical history of the child (recent hospitalization), demographic (child’s age), socioeconomic (educational level of the mother and father's income) and behavioral (age of brush start, weaning age and use of fluoride toothpaste) related to children and to the parents and/or guardians.