Spectrophotometry and chromatography analyses combined with chemometrics tools to differentiate green coffee beans into special or traditional.

Green coffee is the hulled coffee bean, rich in chemical compounds indicative of quality before roasting, making the classification special or traditional. This work aimed to determine compounds in green coffee beans and find the differentiation of green coffee beans into special or traditional ones through chemometrics. For that, the levels of phenolic compounds, reducing, nonreducing, and total sugars were quantified by spectrophotometry: caffeine, trigonelline, 5-hydroxymethylfurfural (5-HMF), 3-hydroxybenzoic, 4-hydroxybenzoic, chlorogenic, caffeic, and nicotinic acids (NAs) by high-performance liquid chromatography-UV-Vis; acetaldehyde, acetone, methanol, ethanol, and isoamyl by HS-GC-FID. Principal component analysis (PCA) was used to differentiate green coffee beans through the levels obtained in spectrophotometric and chromatographic analyses. Statistically, the contents of total phenolic compounds, caffeine, nonreducing sugars, total sugars, NA, 5-HMF, acetaldehyde, ethanol, and ethanol/methanol showed significant differences. The PCA made it possible to classify green coffee beans into special and traditional, in addition to understanding the attributes that influenced the differentiation between coffees. In addition, it was possible to classify green coffee beans into special and traditional, either using all parameters evaluated or only using spectrophotometric analyses. In this way, some advantages allow classification without using a trained and experienced evaluator as their previous experience can influence the results due to their expertise in a certain type of coffee, in addition to being faster and cheaper, especially regarding spectrophotometric analyses.

Environmentally friendly and novel solid-liquid phase microextraction of maneb fungicide in fruits and vegetables.

The dithiocarbamates class has been widely used in agriculture practices because of lower toxicity and instability than organophosphates and carbamates. Among them, the maneb has been used to produce several fruits and vegetables, but its high ingestion can adversely affect human health. This work developed the Solid-Liquid Phase Microextraction (SLPME) for extraction of the maneb in foods sample with posterior determination by Flow injection analysis-Flame Absorption Atomic Spectroscopy (FIA-FAAS). Curve analytical had a linear range from 0.9 to 20.0 µmol L-1 maneb (A = 5.94 × 10-4 C (µmol L-1) + 6.93 × 10-4), good repeatability (4.07%) and reproducibility (3.39%), limits of quantification (5.98 µmol L-1) and detection (0.197 µmol L-1), which was above of the established by regulatory agencies. The extraction of the maneb was performed using 685 µL of the solution of the 1.00 × 10-3 mol L-1 of EDTA, and it has excellent recovery values from 80.85 to 106.51%. Therefore, the developed SLPME demonstrated an alternative environmentally friendly for quickly extracting maneb from food samples (apple, papaya, and tomato).

Effect of drying methods on nutritional constitutes of fermented grape residue.

One of the biggest hurdles faced by the wine industry is the disposal of residual biomass generated after vinification. Although this residue is biodegradable, it constitutes a potential source of environmental pollutants. To alleviate this issue, this biomass may be used in alternative applications; for example, it may be transformed into an enriched flour that can be used to improve the nutrient content in different foods. In this study, were evaluated the effects of drying processes on the relevant nutritional components in dry extracts obtained from the residue of fermented grape pomace. The concentrations of phenolic compounds and anthocyanins were higher when drying the flour by the traditional oven procedure than by freeze-drying. The highest difference (approximately 40%) was observed for tannin compounds. Therefore, drying in an oven is recommended due to the lower loss of bioactive compounds, in addition to being simple and cheap.

The role of 5-hydroxymethylfurfural in food and recent advances in analytical methods.

The thermal processing, storage, and transportation of foodstuffs (e.g., fruit juices, coffee, honey, and vinegar) generate 5-hydroxymethylfurfural (HMF). The food industry uses this compound as a quality marker, thus increasing the demand for fast and reliable analytical methods for its determination. This review focuses on the formation of HMF in food, its desirable and toxic effects, and recent advances in analytical methods for its determination in foodstuffs. The advantages and limitations of these analytical approaches are discussed relative to the main analytical features.

Preconcentration of sulphonamides in bovine milk by the cloud point extraction method using smartphone-based digital images.

Sulphonamides are a group of synthetic antibiotics used specially in veterinary medicine. Among the procedures employed in the sample preparation for sulphonamide determination are liquid-liquid extraction (LLE) and solid-phase extraction (SPE) that use large volumes of organic solvents. Hence, a clean procedure was developed based on preconcentration and cloud point extraction (CPE) without using organic solvents to quantify total sulphonamides in bovine milk. The procedure was optimized as follows: 2 mL of pre-cleaned milk sample, 2 mL of reagent solution and 1 mL of Triton X-114 7% (m/v) were added to a tube, heated in a water bath at 40 °C for 10 minutes and centrifuged at 2950 rcf for 20 minutes. Digital image acquisition was employed directly at the tube without removing the supernatant/aqueous phase. The linear response was observed between 10 and 400 µg L-1 of total sulphonamides and described by the following equation: S = 2.50 + 0.0514C (µg L-1) and R = 0.999. The LOD and the CV (n = 11) were estimated to be 10 µg L-1 and 1.3%, respectively. The main interferents present at their usual concentrations in the sample did not interfere with the results. Spike and recovery tests of total sulphonamides were carried out in UHT and pasteurized milk with recovery values between 73 and 106% and the results obtained for this kind of sample were in agreement with those achieved by a high performance liquid chromatography (HPLC) procedure at the 95% confidence level. The analytical procedure presents an adequate sensitivity to determine total sulphonamides in bovine milk and does not require organic solvents, being aligned to the principles of green chemistry.

Current overview and perspectives in environmentally friendly microextractions of carbamates and dithiocarbamates.

Carbamates and dithiocarbamates are two classes of pesticides widely employed in the agriculture practice to control and avoid pests and weeds, hence, the monitoring of the residue of those pesticides in different foodstuff samples is important. Thus, this review presents the classification, chemical structure, use, and toxicology of them. Moreover, it was shown the evolution of liquid- and solid-phase microextractions employed in the extraction of carbamates and dithiocarbamates in water and foodstuff samples. The classification, operation mode, and application of the microextractions of liquid-phase and solid-phase used in their extraction were discussed and related to the analytical parameters and guidelines of green analytical chemistry.

A spot test for total esters determination in sugarcane spirits exploiting smartphone-based digital images.

Cachaça is an alcoholic beverage produced from sugarcane, whose flavor and taste are related to the esters content, usually expressed as equivalent to ethyl acetate. The official method for the determination of specific esters in cachaça is based on gas chromatography with a flame ionization detector, whereas a volumetric procedure is recommended for determining the total content. Because of the high analytical demand, faster and more practical analytical procedures are required for quality control of the product. The aim of this work was to develop a spot test exploiting smartphone-based digital images for in situ determination of total esters in cachaça. The procedure was based on the reaction of the analytes with hydroxylamine, generating the corresponding hydroxamate ions, which form violet complexes with Fe(iii) in an acidic medium. Digital images were acquired under controlled illumination and converted to RGB values using the PhotoMetrix® 1.8 application. The values of channel B were taken as the analytical response because of the complementarity with the color of the reaction product. A linear response was obtained within 100-500 mg L-1 ethyl acetate, with the coefficient of variation (n = 10) and limit of detection (99.7% confidence level) estimated at 1.1% and 30 mg L-1 ethyl acetate, respectively. The procedure consumes only 1.4 mg NH2OH·HCl and 115 µg Fe(iii) and generates only 900 µL of waste per determination. The results of the proposed procedure agreed with those obtained by the reference volumetric method at the 95% confidence level.

An overview of the Brazilian contributions to Green Analytical Chemistry.

Green Analytical Chemistry (GAC) is a research field that seeks for more sustainable analytical approaches to minimize the toxicity and amounts of wastes without hindering the analytical performance. This is a trend in Analytical Chemistry worldwide and because of the diversity of innovations on this subject, Brazil stands out as the third in the list of the main contributors to GAC, with ca. 11.2% of the published articles. Significant innovations and interesting applications in several fields have been presented and Brazil is continuously moving from Chemistry to Green Chemistry also in the Analytical Chemistry field. Selected contributions for sample preparation, spectro- and electroanalysis, separation techniques, chemometrics, and also procedures for point-of-care measurements are critically reviewed.

Solid-phase extractions in flow analysis.

Coupling solid-phase extraction (SPE) to flow systems has promoted a synergistic development. Whereas SPE mechanization leads to improved precision and higher sample throughput, as well as diminishes systematic errors and contamination risks, analyte concentration and separation from the sample matrix provides a remarkable impact on detectability and selectivity in flow analysis. Historical aspects, main cornerstones, tips for system design, and recent applications are critically reviewed, in the context of analyte(s) separation/concentration, sample clean-up, and release of sorbed chemical species involving both packed (e.g. mini-columns, cartridges, and disks) or fluidized (e.g. beads and magnetic materials) particles. Novel (bio)sorbents, selective synthetic materials, and stationary phases for low-pressure chromatography are also discussed. Moreover, the feasibility of SPE for sample treatment before chromatographic separation, as well as the exploitation of direct measurements on the solid phase (optosensing) are emphasized.

Fluidized particles in flow analysis: potentialities, limitations and applications.

In flow analysis, solid particles (sorbents, reagents or catalysts) have been used for e.g. analyte separation/concentration, sample clean-up, speciation analysis, enzymatic assays, analysis relying on slight soluble reagents, and kinetics studies related to adsorption/release of species. The particles are usually accommodated inside packed-bed mini-columns, cartridges or disks, but this geometry may led to limited analyte/particle interaction, poor renewal of the particle surface, swelling effects, establishment of preferential pathways, and increased backpressure. These hindrances are circumvented by fluidizing the solid particles. Fluidization is a worldwide-accepted industrial process, which can be successfully implemented in flow analysis. This review emphasizes historical and conceptual aspects, as well as advantages, limitations, applications, and perspectives for future development of flow analysis relying on fluidized particles.

Solid-phase extractions in flow analysis

ABSTRACT Coupling solid-phase extraction (SPE) to flow systems has promoted a synergistic development. Whereas SPE mechanization leads to improved precision and higher sample throughput, as well as diminishes systematic errors and contamination risks, analyte concentration and separation from the sample matrix provides a remarkable impact on detectability and selectivity in flow analysis. Historical aspects, main cornerstones, tips for system design, and recent applications are critically reviewed, in the context of analyte(s) separation/concentration, sample clean-up, and release of sorbed chemical species involving both packed (e.g. mini-columns, cartridges, and disks) or fluidized (e.g. beads and magnetic materials) particles. Novel (bio)sorbents, selective synthetic materials, and stationary phases for low-pressure chromatography are also discussed. Moreover, the feasibility of SPE for sample treatment before chromatographic separation, as well as the exploitation of direct measurements on the solid phase (optosensing) are emphasized.

A flow-based procedure exploiting the lab-in-syringe approach for the determination of ester content in biodiesel and diesel/biodiesel blends.

The ester content is an important parameter to be monitored in biodiesel for evaluation of the transesterification reaction yield and for assessing the purity of the final product. This is also a relevant quality parameter in diesel/biodiesel blends to avoid frauds, because legislation establishes a minimum amount of biodiesel to be added to diesel. The official method EN14103 requires the addition of an alternative internal standard (methyl nonadecanoate) for analysis of biodiesel from bovine tallow because the methyl heptadecanoate is found in high amounts in this product. In this work, it is proposed a fast, simple, practical, and environmental friendly flow-based spectrophotometric procedure, which exploits the formation of the violet complex between Fe(III) and the hydroxamate generated by the reactions of the alkyl esters with hydroxylamine. All involved steps are carried out inside the syringe pump of a sequential injection analyzer (lab-in-syringe approach). A single phase is attained by using ethanol as mediator solvent between the organic sample and aqueous soluble reagents. Linear responses for biodiesel samples and diesel/biodiesel blends were obtained from 4-99%(v/v) to 2.0-40%(v/v) methyl esters, described by the equations: A = 0.342 + 0.00305C (r = 0.997) and A = 0.174 + 0.00503C (r = 0.999), respectively. The analytical curve can be obtained by in-line dilution of a methyl linoleate stock solution. For biodiesel samples, the coefficient of variation (n = 10), limit of detection (99.7% confidence level), and sampling rate were estimated at 0.8%, 0.36%(v/v), and 15h-1, respectively, whereas the corresponding values for the blend samples were 0.20%, 0.03%(v/v), and 12h-1, respectively. The procedure consumes only 860µg of hydroxylamine, 366µg of Fe2(SO4)3·H2O, and 2.0mL ethanol and generates ca. 3.0mL of residue per determination. The results agreed with those obtained by official methods EN14103/2011 e EN14078, at the 95% confidence level.

A sensitive flow-based procedure for spectrophotometric speciation analysis of inorganic bromine in waters.

A flow-based system with solenoid micro-pumps and long path-length spectrophotometry for bromate and bromide determination in drinking water is proposed. The method is based on the formation of an unstable dye from the reaction between bromate, 2-(5-dibromo-2-pyridylazo)-5-(diethylamino)phenol (5-Br-PADAP) and thiocyanate ions. A multivariate optimization was carried out. A linear response was observed between 5.0 and 100 µg L(-1) BrO3(-) and the detection limit was estimated as 2.0 µg L(-1) (99.7% confidence level). The coefficient of variation (n=20) and sampling rate were estimated as 1.0% and 40 determinations per hour, respectively. Reagent consumption was estimated as 0.17 µg of 5-Br-PADAP and 230 µg of NaSCN per measurement, generating 6.0 mL of waste. Bromide determination was carried out after UV-assisted conversion with K2S2O8 using 300 µL of sample within the range 20-400 µg L(-1) Br(-). The generated bromate was then determined by the proposed flow system. The results for tap and commercial mineral water samples agreed with those obtained with the reference procedure at the 95% confidence level. The proposed procedure is therefore a sensitive, environmentally friendly and reliable alternative for inorganic bromine speciation.

Green chemistry and the evolution of flow analysis. A review.

Flow analysis has achieved its majority as a well-established tool to solve analytical problems. Evolution of flow-based approaches has been analyzed by diverse points of view, including historical aspects, the commutation concept and the impact on analytical methodologies. In this overview, the evolution of flow analysis towards green analytical chemistry is demonstrated by comparing classical procedures implemented with different flow approaches. The potential to minimize reagent consumption and waste generation and the ability to implement processes unreliable in batch to replace toxic chemicals are also emphasized. Successful applications of greener approaches in flow analysis are also discussed, focusing on the last 10 years.

Versatile microanalytical system with porous polypropylene capillary membrane for calibration gas generation and trace gaseous pollutants sampling applied to the analysis of formaldehyde, formic acid, acetic acid and ammonia in outdoor air.

The analytical determination of atmospheric pollutants still presents challenges due to the low-level concentrations (frequently in the µg m(-3) range) and their variations with sampling site and time. In this work, a capillary membrane diffusion scrubber (CMDS) was scaled down to match with capillary electrophoresis (CE), a quick separation technique that requires nothing more than some nanoliters of sample and, when combined with capacitively coupled contactless conductometric detection (C(4)D), is particularly favorable for ionic species that do not absorb in the UV-vis region, like the target analytes formaldehyde, formic acid, acetic acid and ammonium. The CMDS was coaxially assembled inside a PTFE tube and fed with acceptor phase (deionized water for species with a high Henry's constant such as formaldehyde and carboxylic acids, or acidic solution for ammonia sampling with equilibrium displacement to the non-volatile ammonium ion) at a low flow rate (8.3 nL s(-1)), while the sample was aspirated through the annular gap of the concentric tubes at 2.5 mL s(-1). A second unit, in all similar to the CMDS, was operated as a capillary membrane diffusion emitter (CMDE), generating a gas flow with know concentrations of ammonia for the evaluation of the CMDS. The fluids of the system were driven with inexpensive aquarium air pumps, and the collected samples were stored in vials cooled by a Peltier element. Complete protocols were developed for the analysis, in air, of NH(3), CH(3)COOH, HCOOH and, with a derivatization setup, CH(2)O, by associating the CMDS collection with the determination by CE-C(4)D. The ammonia concentrations obtained by electrophoresis were checked against the reference spectrophotometric method based on Berthelot's reaction. Sensitivity enhancements of this reference method were achieved by using a modified Berthelot reaction, solenoid micro-pumps for liquid propulsion and a long optical path cell based on a liquid core waveguide (LCW). All techniques and methods of this work are in line with the green analytical chemistry trends.

A greener and highly sensitive flow-based procedure for carbaryl determination exploiting long pathlength spectrophotometry and photochemical waste degradation.

An environmentally friendly analytical procedure with high sensitivity for determination of carbaryl pesticide in natural waters was developed. The flow system was designed with solenoid micro-pumps in order to improve mixing conditions and minimize reagent consumption as well as waste generation. A long pathlength (100 cm) flow cell based on a liquid core waveguide (LCW) was employed to increase the sensitivity in detection of the indophenol formed from the reaction between carbaryl and p-aminophenol (PAP). A clean-up step based on cloud-point extraction was explored to remove the interfering organic matter, avoiding the use of toxic organic solvents. A linear response was observed within the range 5-200 microg L(-1) and the detection limit, coefficient of variation and sampling rate were estimated as 1.7 microg L(-1) (99.7% confidence level), 0.7% (n=20) and 55 determinations per hour, respectively. The reagents consumption was 1.9 microg of PAP and 5.7 microg of potassium metaperiodate, with volume of 2.6 mL of effluent per determination. The proposed procedure was selective for the determination of carbaryl, without interference from other carbamate pesticides. Recoveries within 84% and 104% were estimated for carbaryl spiked to water samples and the results obtained were also in agreement with those found by a batch spectrophotometric procedure at the 95% confidence level. The waste of the analytical procedure was treated with potassium persulphate and ultraviolet irradiation, yielding a colorless residue and a decrease of 94% of total organic carbon. In addition, the residue after treatment was not toxic for Vibrio fischeri bacteria.

An improved procedure for flow-based turbidimetric sulphate determination based on a liquid core waveguide and pulsed flows.

An improved flow-based procedure is proposed for turbidimetric sulphate determination in waters. The flow system was designed with solenoid micro-pumps in order to improve mixing conditions and minimize reagent consumption as well as waste generation. Stable baselines were observed in view of the pulsed flow characteristic of the systems designed with solenoid micro-pumps, thus making the use of washing solutions unnecessary. The nucleation process was improved by stopping the flow prior to the measurement, thus avoiding the need of sulphate addition. When a 1-cm optical path flow cell was employed, linear response was achieved within 20-200mgL(-1), described by the equation S=-0.0767+0.00438C (mgL(-1)), r=0.999. The detection limit was estimated as 3mgL(-1) at the 99.7% confidence level and the coefficient of variation was 2.4% (n=20). The sampling rate was estimated as 33 determinations per hour. A long pathlength (100-cm) flow cell based on a liquid core waveguide was exploited to increase sensitivity in turbidimetry. Baseline drifts were avoided by a periodical washing step with EDTA in alkaline medium. Linear response was observed within 7-16mgL(-1), described by the equation S=-0.865+0.132C (mgL(-1)), r=0.999. The detection limit was estimated as 150microgL(-1) at the 99.7% confidence level and the coefficient of variation was 3.0% (n=20). The sampling rate was estimated as 25 determinations per hour. The results obtained for freshwater and rain water samples were in agreement with those achieved by batch turbidimetry at the 95% confidence level.