This study determined the levels of total mercury in Spanish samples of baby food, fast food, and daily meal, which people of different ages consume, to evaluate potential toxicological risks through the contribution to the tolerable daily intake (TDI). The total mercury concentrations were determined in thirteen commercial baby foods for infants 6 to 12 months old, six types of fast foods prepared for children, and nine canteen menus prepared for adults. Samples were analyzed using a direct mercury analyzer, and the following concentration ranges were found: baby food (0.57-41.9 µg kg-1), fast food (0.54-68 µg kg-1), and adult menus (0.43-638 µg kg-1). The recovery of different amounts of spiked mercury ranged from 98.6 to 104.9%, and the method’s accuracy was checked with an analysis of different certified reference materials. The limits of detection and quantification obtained were 0.1 and 0.3 µg kg-1, respectively, with a relative standard deviation of up to 11%. The contribution of the samples to the TDI varied as follows: baby food (0.3-28%), fast food (0.5-102%), and adult menus (0.3-396%). Therefore, it was concluded that total mercury daily intake does not pose risks for Spanish children and adults if tuna is not included on their menu.

In this work, carbon dots (CDs) prepared by a one-step hydrothermal method were employed for the determination of quercetin in teas and beers. The fluorescence quenching of CDs was proportional to the concentration of quercetin. Under optimum experimental conditions, linear quenching was observed for quercetin in the range of 1.0 to 10 mg L-1 (F/F0 = (0.1511 ± 0.0075)[Q] + (0.8922 ± 0.0384), R2 = 0.9926), at room temperature, using 80 μL CDs and 0.1 mol L-1 Na2HPO4/NaOH buffer solution (pH 11.0). A limit of detection (3σ criterion) of 0.85 mg L-1, and a relative standard deviation of 0.21% (n = 3) for 4.0 mg L-1 quercetin solution was obtained. Addition and recovery tests with tea and beer samples were performed resulting in recoveries at the range between 80 and 118%. This procedure served successfully to determine quercetin in beer and tea samples presenting high sample throughput.

ABSTRACT A multicommuted flow procedure for the spectrophotometric determination of reducing sugars in wine has been developed. A dialysis unit was incorporated in the system to minimize matrix interferences and eliminate the colored compounds of the wine. The oxidation-reduction reaction in an alkaline medium between reducing sugars and the Cu2+-Neocuproine complex was employed. The compound formed was monitored at 460 nm. In the proposed procedure, there was a linear response between 0.25 and 4.0 g L-1 reducing sugars (y = (0.36 ± 0.02) + (0.31 ± 0.01) * x, R = 0.9975, n = 6), a coefficient of variance of 2.6% for a reducing sugar solution of 2.0 g L-1 (n = 7), a limit of detection estimated at 0.03 g L-1, reagent consumption per determination of 0.330, 0.128 and 0.160 mg for neocuproine, CuSO4 and NaOH, respectively. A sampling throughput of 45 determinations per hour was achieved. The proposed system was applied to wine samples and comparing the results with an AOAC official method no significant difference at a 95% confidence level.

Neste trabalho foi proposto um método de análise em fluxo por multicomutação para a determinação de amoxicilina em formulações farmacêuticas. O método proposto é baseado na reação de diazotização da o-nitroanilina com amoxicilina em meio alcalino, produzindo um composto amarelo que foi monitorado em 435 nm. As características do método foram: faixa linear de 25 até 400 mg L-1 de amoxicilina, limite de detecção de 5,1 mg L-1, frequência analítica de 50 determinações por hora e desvio padrão relativo inferior a 3,9% (n = 10) para uma amostra típica de 100 mg L-1 amoxicilina. Para verificar a exatidão do método, as amostras foram analisadas empregando um método independente e aplicando-se o teste-t pareado não houve diferença significativa no nível de confiança de 95%.

A multicommuted flow analysis method for the spectrophotometric determination of amoxicillin in pharmaceutical formulations is reported. The proposed method is based on the reaction of diazotised o-nitroaniline with amoxicillin in an alkaline medium, producing a yellow compound that was monitored at 435 nm. The main features of the method were: a linear relationship with amoxicillin concentration ranging from 25 to 400 mg L-1; a detection limit of 5.1 mg L-1; an analytical throughput of 50 determinations per hour; and a relative standard deviation lower than 3.9% for a typical amoxicillin sample with concentration of 100 mg L-1 (n = 10). To verify the accuracy of the method, samples were also analyzed employing an independent method, and applying the paired t-test to the results no significant difference at the 95% confidence level was observed.

Neste trabalho foi desenvolvido um procedimento empregando multicomutação em fluxo e reação enzimática para determinação espectrofotométrica de L(+)lactato proveniente da fermentação alcoólica de vinho (mosto de cana de açúcar) O método espectrofotométrico foi baseado na reação com a enzima lactato oxidase, seguida pela reação com a enzima peroxidase e posterior condensação entre 4-clorofenol e 4 -aminoantipirina. O módulo de análise foi constituído por um conjunto de três válvulas solenóides, bomba peristáltica, espectrofotômetro e microcomputador equipado com interface de controle. Um programa escrito em QuickBASIC 4.5 foi desenvolvido para controlar as válvulas solenóides e realizar aquisição de dados. Amostras na faixa de concentração de 5,0 a 100,0 mg L-1 de L(+)lactato foram analisadas usando uma solução contendo 150 UI de lactato oxidase e 200 UI de peroxidase. Outras características analíticas tais como, desvio padrão relativo de 2% (n = 15) para uma amostra típica contendo 38,5 mg L-1 de L(+)lactato; freqüência de amostragem de 36 determinações por hora; e baixo consumo de reagentes (1,0 mig de 4-clorofenol e 0,1 mig 4-aminoantipirina) por determinação também foram obtidas.

A multicommutation flow system for the spectrophotometric determination of L(+)lactate in alcohol fermented sugar cane juice is proposed. The spectrophotometric method was based on the L(+)lactate conversion to pyruvate plus hydrogen peroxide by the lactate oxides enzyme, followed by reaction with peroxidase enzyme and condensation between 4-chlorophenol and 4-aminoantipyrine. The flow system network comprised three three-way solenoid valves controlled by a microcomputer that running a software wrote in Quick BASIC 4.5 provided also facilities to perform data acquisition. After optimization of system parameters, a set of alcohol fermented juice was analyzed to prove the procedure feasibility. Samples with concentration raging from 5.0 to 100.0 mg L-1 L(+)lactate were analyzed using a 150 UI lactate oxidize and 200 UI peroxidase enzymatic solution. Other advantageous features such as a relative standard deviation of 2% (n = 15) for a typical sample containing 38.5 mg L-1 L(+)lactate; an analytical throughput of 36 determination per hour; and a low reagent consumption 1.0 mug 4-chlorophenol and 0.1 mug 4-aminoantipyrine per determination were also achieved.

A flow system procedure for spectrophotometric determination of ascorbic acid in drugs based on [Fe3+(SCN-)n]+3-n complex decomposition by reduction is described. The flow network was constituted by a set of three-way solenoid valves, controlled by a microcomputer running a software wrote in QuickBasic 4.5 language. The feasibility of the procedure was ascertained by determining ascorbic acid in drug samples with mass ranging from 0.0018 up to 0.0180 g. The results showed an agreement of about 7% when compared with recommended method. Other profitable features such as a standard deviation of 1.5% (n = 7) and a throughput of 120 determinations per hour was also achieved.