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This worlk proposes a rapid, sensitive and accurate flow-batch digital image colorimetric (FB-DIC) system to zinc oxid determination in ointments. The method was based on the reaction between Zn(II) ions and zincon at pH = 9.0. The Zn(II)-zincon complex was formed and detected in the mixing chamber. It was designed with two opposite glass windows: one for the webcam and other for the ultra-bright LED. Absorbance was calculated by the norm of the vector in the RGB space. The method had a linear range between 1.0-8.2 mg L–1 with R2 = 0.9998 (n=8) and limit of detection estimated as 5.7 mg L–1. The relative standard deviation (RSD) and sample throughput were estimated at 0.06% and 109 samples h-1, respectively. Ointment commercial samples were analyzed by FB-DIC and the refference method. The results shown no statistically significant difference between them, when was applied the paired t-test at the 95% confidence level. According to green analytical chemistry (GAC) principles the FB-DIC system can be considered eco-driendly due to its low samples and reagents consumption as its low waste generation.

RESUMO A pesquisa descreve a reação espectrofotométrica do complexo Cu(II)-PAN (1-(2-piridilazo)-2-naftol) e determina a concentração de cobre (II) em aguardente de mandioca (Tiquira). Para isso, dimensionamos a reação para os estudos de absorção do complexo, pH, estabilidade, proporção estequiométrica, interferentes, correlação e recuperação. Após essa etapa, determinamos a concentração de cobre(II) em cinco amostras de bebidas destiladas artesanalmente de cinco municípios do Estado do Maranhão. O resultados mostram que o complexo absorve em 548 nm em pH 6, é estável em um tempo de 7 horas em proporções estequiométrica mínima de 1:1 do ligante e metal, possui limite de detecção em 3,3 X 10-2 mg L-1, faixa de linearidade de 1 X 10-6 a 1 X 10-5 mol L-1, correlação (R2= 0,9990), desvio padrão=0,0035 e recuperação em 104,54 ± 7,01 e os principais íons interferentes são o ferro (III) e o cobalto (II). Na aguardente, constatamos que o teor de cobre está acima do permitido pela legislação brasileira. SUMMARY The search describes the spectrophotometric reaction of the Cu (II)-PAN (1-(2-pyridilazo) -2-naphthol) complex and determines the concentration of copper (II) in manioc spirit (Tiquira). For this, we dimensioned the reaction for the studies of complex absorption, pH, stability, stoichiometric ratio, interferences, correlation, and recovery. After this step, we determined the concentration of copper (II) in five samples of beverages distilled artisanal from five municipalities of the State of Maranhão. The results show that the complex absorbs at 548 nm at pH 6, is stable at a time of 7 hours in minimum 1:1 stoichiometric proportions of the binder and metal, has a detection limit in 3.3 X 10-2 mg L-1, range (R2= 0.9990), standard deviation= 0.0035 and recovery at 104.54 ± 7.0, and the main interfering ions are iron (III) and cobalt (II). In the brandy, we find that the copper content is above that allowed by Brazilian legislation.

A flow-injection spectrometric method for determination of sodium diclofenac in pharmaceutical formulations was developed on this work. Sodium diclofenac solutions were injected into a stream of deionized water that reacted with potassium permanganate on acid medium producing Mn2+ ions whose exhibit maximum absorbance at 450 nm. The methodology used optimize experimental parameters was 33 factorial design and response surface. The proposed method obeyed the Beer’s Law over the range 25-160 mg L-1, applied in tablets and ampoules samples. Results were compare with the reference method. It was verified at the 95% confidence level, through paired t -test application – there is no statistic difference between them. The detection limit was valued in 2.6 mg L-1, relative standard deviation for 10 consecutive injections was 1.5% (100.0 mg L-1 sodium diclofenac solution) and the sample throughput was 80 samples h-1. Regarding optimization of operational conditions, the FIA spectrometric method presented analytical performance as good as other elaborated flow analyzers. Offers a simple and inexpensive way to this drug indirect determination aiming quality control on pharmaceutical industry’s assembly line. However, it can not be used for adulteration screening analysis due to non-selectivity and non-specificity of redox reactions.

portuguesEste trabalho descreveu e comparou quatro estudos entre si que utilizaram metodos automaticos em fluxo com deteccao espectrofotometrica e a reacao de oxidacao do diclofenaco para determinar diclofenaco em formulacoes farmaceuticas e fluidos corporais. Para isso, utilizamos os seguintes artigos: Versatility of a multicommuted flow system in the spectrometric determination of three analytes, Sequential injection spectrophotometric method for the assay of anti-inflammatory diclofenac sodium in pharmaceutical preparations, Screening of conditions controlling spectrophotometric sequential injection analysis e Sequential injection spectrophotometric determination of diclofenac in urine and pharmaceutical formulations e detalhamos as metodologias empregadas, os resultados, conclusoes obtidas e comparamos entre eles os limites de deteccao, desvio padrao relativo e a frequencia analitica. Os resultados mostraram diferencas significativas entre metodos empregados e a utilizacao do Sistema automatico do tipo Analise por Injecao Sequencial, apesar deste possuir menor frequencia analitica. EnglishThis study described and compared four studies that used automatic flow methods with spectrophotometric detection and the oxidation reaction of diclofenac to determine diclofenac in pharmaceutical formulations and body fluids. For this, the following articles were used: Versatility of a multicommuted flow system in the spectrometric determination of three analytes, Sequential injection spectrophotometric method for the assay of anti-inflammatory diclofenac sodium in pharmaceutical preparations, Screening of conditions controlling spectrophotometric sequential injection analysis and Sequential injection spectrophotometric determination of diclofenac in urine and pharmaceutical formulations and we detail the methodologies used, the results, the conclusions obtained and compare the limits of detection, relative standard deviation and analytical frequency. The results showed significant differences between the employed methods and the use of the Automatic System of the Sequential Injection Analysis type, although this one has a lower analytical frequency.

This paper proposes a method to perform rapid and sensitive graphite furnace atomic absorption spectrometry (GFAAS) determination of Cr(VI) in vinegar samples without wet digestion. Taking into account low levels of Cr(VI) and the presence of several concomitants in the sample matrix, the proposed method uses single-phase liquid-liquid extraction (SPLLE). The method is automated, employing a flow-batch analyzer (FBA) which uses a mixing chamber designed to emulate a separation funnel promoting the formation/break of the single-phase solution, reaction and extraction. The Cr(VI) extraction procedure was performed by proportioned mixing of the vinegar sample (aqueous phase), amyl alcohol (organic phase), and ethanol (consolute) to form a single-phase solution. The chelating reagent sodium diethyldithiocarbamate (DDTC) dissolved in the consolute reacts rapidly with Cr(VI), in the single phase to produce a stable Cr-DDTC complex. The single-phase break step is performed by adding an excess of Britton-Robinson buffer, and then the organic phase enriched with Cr(VI) was analyzed by GFAAS. Factors such as extraction steps, single-phase composition, pH, chelating agent concentration, and flow-batch parameters were optimized. The FBA-SPLLE-GFAAS was evaluated in vinegar samples showing satisfactory analytical features in terms of limit of quantification (0.86 μg L −1 ), precision (RSD

In this paper, a flow-batch analysis (FBA) system, hydride generation (HG), and atomic fluorescence spectrometry (AFS) are coupled for the first time to develop a fast and sensitive FBA–HG–AFS method for automated inorganic antimony speciation in waters, whether from the sea, mineral water, tap water, or lakes. Unlike previous automated flow methods that use confluent fluids and complex devices, the main advantage of the proposed FBA-HG-AFS method is an innovative use of a simple laboratory made flow-batch chamber to simultaneously perform mixing, homogenization, reactions, antimony hydride formation, and gas–liquid separation. The FBA-HG-AFS method was optimized using two–level full factorial and Box–Behnken designs, and validated on the basis of real repeated measurements and analysis of variance, yielding a satisfactory working range (100–2000 ng L−1), precision (RSD = 4%), sensitivity, and limit of detection (6 ng L−1) for the water samples analyzed. Accuracy was evaluated by recovery tests and analysis of a standard reference material (SRM 1643e) of trace elements in water (NIST, USA), resulting in recovery rates of from 90 to 114%, and relative error = 0.7%. The high sampling throughput (54 speciations h−1), together with low waste generation, low costs, low reagent and sample consumption make this FBA-HG-AFS method an interesting proposal for fast large-scale analysis in routine laboratoy according to the principles of green analytical chemistry.

A new method referred to as microemulsion-based Dispersive Magnetic Solid-Phase Extraction (MDM-SPE) is presented for use in the extraction and preconcentration of metal ions from complex organic matrices. MDM-SPE combines the features of magnetic nanoparticles (MNPs) and microemulsions. It was successfully applied to the extraction of copper(II) from gasoline prior to its determination by Graphite Furnace Atomic Absorption Spectrometry (GF-AAS). The material for use in MDM-SPE was obtained by first functionalizing MNPs of the type Fe3O4@Al2O3 with sodium dodecyl sulfate and the chelator 1-(2-pyridylazo)-2-naphthol (PAN) dispersed in 1-propanol. The resulting functionalized magnetic MNPs were dispersed in a microemulsion prepared from gasoline, buffer, and 1-propanol. After waiting for 5 s (during which the formation of the copper complex on the MNPs is complete), the MNPs are magnetically separated. The complex was then eluted with 2 mol L−1 HNO3, and the eluate submitted to GF-AAS. Various parameters were optimized. Copper(II) can be quantified by this method over a linear range that extends from 2.0 to 10.0 μg·L−1. Other figures of merit include (a) a 37 ng·L−1 detection limit, (b) a repeatability of 1.1%, (c) a reproducibility of 2.1%, and (d) an enrichment factor of nine. The high surface-to-volume ratio of the microemulsion containing the dispersed magnetic sorbent warrants an efficient contact for reaction between copper(II) and the complexing agent, and this results in fast (about 40 s) extraction and pre-concentration of copper(II). MDM-SPE is accurate, precise and efficient. Microemulsions do not break down, and phase separation, heating, laborious, and time-consuming sample preparation, and incorporation of impurities into the graphite furnace (which can generate inaccuracies in GF-AAS analysis) are not needed.

This study proposes a digital image-based flow-batch analyzer (DIB-FBA) for aluminum (III) and chromium (VI) determinations in natural water. A webcam with a CCD sensor and RGB data are used. The method for determining aluminum is based on an Al(III) ion, quercetin, and cetyltrimethylammonium bromide (CTAB) reaction which yields a yellow colored complex in an acetate buffer medium (pH 5.5). The determination of chromium is based on a Cr(VI) ion with 1,5-diphenylcarbazide (DPC) reaction whose product is a violet colored complex. Digital images present the color of the emergent (complementary) radiation to that absorbed by the complexes formed in each analysis. RGB data were employed to build the analytical curves. All standard solutions were prepared in-line, and all analytical processes were completed by simply changing the operational parameters in the DIB-FBA control software. The working ranges were from 10 to 600 μg L − 1 for Al(III) with r = 0.9994 (n = 5), and 10 to 300 μg L − 1 for Cr(VI) with r = 0.999 (n = 5), the limits of detection were 3.97 and 2.65 μg L − 1 respectively for Al(III) and Cr(VI). The relative standard deviation (RSD %) and sampling rate were estimated at 1.5% and 137 h − 1 and at 1.7% and 134 h − 1 for Al(III) and Cr(VI), respectively. Comparing with the reference method, no statistically significant differences were observed when applying the paired t -test at a 95% confidence level.

The traditional flow chemiluminescence (CL) systems typically use flow cells in spiral shape mounted in front of a photomultiplier tube (PMT). The sample is transported by using carrier fluids, undergoes dispersion, and mixes with reagents and CL reaction occurs before reaching the flow cell. As a consequence, the maximum of the chemiluminescence intensity is not exploited and the sensitivity is significantly diminished. In this work, these drawbacks were overcome by using a flow–batch approach and a large area silicon photodiode instead of PMT in order to build a simple and automatic luminometer for CL measurements. The feasibility of the proposed flow–batch luminometer was demonstrated in the determination of vitamin B 12 in injection ampoules, yielding limits of detection and quantification (0.11 and 0.36 μg L − 1 , respectively), recovery rates (between 97.8 and 102.1%), relative standard deviations (RSD − 1 ). Thus, it was possible to both project and build a simple, flexible, versatile and automatic luminometer, while keeping the excellent characteristics of the previous flow–batch analyzer such as: low reagent and sample consumption and minimal waste generation.

A fast, reliable, and low cost biamperometric flow‐injection method, with an error of 1.3% and an analytical throughput of 55 samples h−1, for determination of tetracycline hydrochloride in pharmaceuticals capsules is proposed. The analytical curve was linear (r=0.998) in the range 10 to 50 mg l−1 using Fe(CN)6 3− and NaOH solutions as reagent and carrier stream/supporting electrolyte, respectively. A relative standard deviation of 1.6% (10 sequential injections of 30.0 mg l−1) was verified with detection and quantification limits of 0.6 and 3.4 mg l−1, respectively.

A digital image-based flame emission spectrometric (DIB-FES) method for the quantitative chemical analysis is proposed here for the first time. The DIB-FES method employs a webcam to capture the digital images which are associated to a radiation emitted by the analyte into an air-butane flame. Since the detection by webcam is based on the RGB (red-green-blue) colour system, a novel mathematical model was developed in order to build DIB-FES analytical curves and estimate figures of merit for the proposed method. In this approach, each image is retrieved in the three R, G and B individual components and their values were used to define a position vector in RGB three-dimensional space. The norm of this vector is then adopted as the RGB-based value (analytical response) and it has revealed to be linearly related to the analyte concentration. The feasibility of the DIB-FES method is illustrated in three applications involving the determination of lithium, sodium and calcium in anti-depressive drug, physiological serum and water, respectively. In comparison with the traditional flame emission spectrometry (trad-FES), no statistic difference has been observed between the results by applying the paired t-test at the 95% confidence level. However, the DIB-FES method has offered the largest sensitivities and precision, as well as the smallest limits of detection and quantification for the three analytes. These advantageous characteristics are attributed to the trivariate nature of the detection by webcam.