Variability of Bile Baseline Excitation-emission Fluorescence of Two Tropical Freshwater Fish Species.

The quantification of pollutant metabolites in fish bile is an efficient approach to xenobiotic pollution monitoring in freshwaters since these measurements directly address exposure. Fluorescence excitation-emission matrix spectroscopy (EEMS) has demonstrated to be a highly specific and cost-effective technique for polycyclic aromatic hydrocarbon (PAH) and PAH-metabolite identification and quantification. EEMS ability to quantify these compounds strongly depends on the intensity and variability of the bile baseline fluorescence (BBF). We found large differences in BBF among Aequidens metae (AME) individuals and of these with Piaractus orinoquensis (PIO). Moreover, BBF was large enough that solvent dilutions of over 1:400 were needed to avoid inner filter effects. We used parallel factor analysis (PARAFAC) to model the intra- and inter-species BBF variability. PARAFAC successfully decomposed the EEMS set into three fluorophores present in all samples, although in concentrations spreading over ~ 3 orders of magnitude. One of the factors was identified as tryptophan. Tryptophan and Factor 2 were covariant and much more abundant in AME than in PIO, while Factor 3 was ~ 6 times more abundant in PIO than in AME. Also, tryptophan was ~ 10x more abundant in AME specimens immediately caught in rivers than in their laboratory-adapted peers. The PARAFAC decomposition effectiveness was confirmed by the positive proportionality of scores to dilution ratios. A large inner filter indicates that Factor 2 is as strong a light absorber as tryptophan. Our results stress the need to include bile matrix variable components for the detection and quantification of pollutant metabolites using PARAFAC.

Discrimination between Covid-19 positive and negative blood serum based on excitation-emission matrix fluorescence spectroscopy and chemometrics.

The outbreak of the disease caused by the SARS-CoV-2 virus (Covid-19) has resulted in a global health emergency that has caused millions of deaths in recent years. The control of the pandemic was significantly impacted by the availability of inputs and qualified labor to correctly diagnose the population. The challenges faced by numerous countries in conducting this extensive diagnosis, utilizing methods such as RT-PCR, emphasize the necessity for alternative testing strategies that are less reliant on expensive raw materials and can be implemented on a larger scale. This paper proposes a methodology for classifying blood serum samples as either positive or negative for Covid-19 infection using excitation-emission matrix (EEM) fluorescence spectroscopy associated with multivariate analysis. The proposed methodology uses EEM spectra of samples diagnosed by the reference method (RT-PCR) to train and validate classification models. Two approaches were tested: the first using PARAFAC and the second by unfolding the excitation-emission matrices. The DD-SIMCA model performed best in the PARAFAC approach, with an error rate of 0.05, sensitivity of 0.98 and specificity of 0.96. The PLS-DA and PCA-DA models in the second approach effectively distinguished between classes. The PCA-DA model performed the best with an error rate of 0.06 and sensitivity and specificity of 0.94. Fluorescence spectroscopy was found to be effective in analyzing serum samples and obtaining discrimination models to determine if a patient is infected with SARS-CoV-2. The findings are encouraging and could aid in the development of an inexpensive and reliable auxiliary diagnostic method.

Non-conservative behavior of organic matter and its interaction with metals in an equatorial estuary, Brazil.

Droughts are becoming more intense and frequent in the Brazilian semiarid because of El Niño and global climate changes. The Jaguaribe River estuary is a semiarid ecosystem that experiences a reduction in freshwater discharges due to droughts and river damming. The decrease in freshwater fluxes has increased metal availability through the water residence time increase in the Jaguaribe River estuary. Then, this study aimed to evaluate the dissolved organic matter quality and its interaction with metals in the Jaguaribe River estuary after a severe drought period. It was performed through carbon analyses, fluorescence spectroscopy, ultrafiltration technique, and determinations of metals by ICP-MS. Optical analysis showed that the dissolved organic carbon (DOC) was preponderantly composed of terrestrial-derived humic compounds, while the low ratio between the particulate organic carbon (POC) and chlorophyll-a indicated that POC was predominantly phytoplankton-derived. DOC and POC presented non-conservative removal during the estuarine mixing. DOM and dissolved elements were mostly distributed within the LMW fraction and presented a low percentage in the colloidal fraction. Li, Rb, Sr, Mo, and U showed conservative behavior, while Cu, Fe, Cr, and V had non-conservative behavior with a significant positive correlation with DOM, suggesting DOM as a relevant driver of metal availability at the Jaguaribe River estuary even during the rainy season.

A fluorescence-based multivariate method for biodiesel quantification in undiluted diesel-biodiesel blends without sample preparation.

In this work, excitation-emission matrices (EEMs) were used in association with parallel factor analysis (PARAFAC) to assess biodiesel content in undiluted diesel-biodiesel blends (DBBs) without pre-sample preparation. EEMs were decomposed using the PARAFAC (EEMs-PARAFAC), and the loading values of the PARAFAC component as a function of biodiesel content in the blends were used to build an analytical model to quantify the biodiesel content in DBBs. The proposed model presenting a limit of detection (LOD) and a limit of quantification (LOQ) of 2.5% and 11% w/w, respectively, successfully predicted the biodiesel content in the validation samples. The robustness of the model was confirmed by a close analysis of the root mean square error of prediction, standard error of prediction, relative standard deviation of prediction, and Bias. Therefore, an accurate and robust analytical model based on EEMs-PARAFAC was developed to quantify the biodiesel content in undiluted DBBs without sample preparation.

In situ extraction/encapsulation of olive leaves antioxidants in zein for improved oxidative stability of edible oils.

This study presents a sustainable and cost-effective method for preserving the bioactivity of phenolic compounds in olive leaves (OLE) during their application. The extraction and nanoencapsulation of OLE were performed in a single-step process using a rotor-stator system with zein as the encapsulating agent. The nanoprecipitation step was carried out using an aqueous sodium caseinate solution, resulting in spherical particles with an average diameter of about 640 nm, as confirmed by Transmission Electron Microscopy. Thermal characterization showed that the produced nanoparticles were more thermally stable than free OLE until 250 °C, and FTIR spectra indicated effective interaction between the phenolic compounds and zein. Antioxidant activity was evaluated using TBARS, DPPH, ABTS, and FRAP assays, with results showing that encapsulated OLE had lower antioxidant activity than free OLE. The best antioxidant capacity results were determined by TBARS assay, with IC50 results equal to 43 and 103 µgOLE/mL for free and encapsulated OLE, respectively. No anti-inflammatory potential was detected for both samples using the RAW 264.7 model, and only free OLE showed cytotoxic activity against lung cancer and gastric carcinoma. Encapsulated and free OLE were used as antioxidants in soy, palm, and palm kernel oils and compared to BHT using Rancimat. The Schaal Oven Test was also performed, and the PARAFAC chemometric method analyzed the UV-Vis spectra, which revealed high stability of the oil when 300 mg or the nanoparticles were added per kg oil. Results suggested that zein-encapsulated olive leaf antioxidants can improve the oxidative stability of edible oils.

Study of the Stability of Wine Samples for 1H-NMR Metabolomic Profile Analysis through Chemometrics Methods.

Wine is a temperature, light, and oxygen-sensitive product, so its physicochemical characteristics can be modified by variations in temperature and time when samples are either sampled, transported, and/or analyzed. These changes can alter its metabolomic fingerprinting, impacting further classification tasks and quality/quantitative analyses. For these reasons, the aim of this work is to compare and analyze the information obtained by different chemometric methods used in a complementary form (PCA, ASCA, and PARAFAC) to study 1H-NMR spectra variations of four red wine samples kept at different temperatures and time lapses. In conjunction, distinctive changes in the spectra are satisfactorily tracked with each chemometric method. The chemometric analyses reveal variations related to the wine sample, temperature, and time, as well as the interactions among these factors. Moreover, the magnitude and statistical significance of the effects are satisfactorily accounted for by ASCA, while the time-related effects variations are encountered by PARAFAC modeling. Acetaldehyde, formic acid, polyphenols, carbohydrates, lactic acid, ethyl lactate, methanol, choline, succinic acid, proline, acetoin, acetic acid, 1,3-propanediol, isopentanol, and some amino acids are identified as some of the metabolites which present the most important variations.

Analytical and chemometric strategies for elucidation of yerba mate composition.

Yerba mate, a popular plant consumed mainly as an infusion, possesses nutritional and medicinal properties attributed to its secondary metabolites. This study aimed to develop strategies to elucidate the phenolic composition of yerba mate samples from Brazil, Argentina, Uruguay, and Paraguay. Optimization of ultrasonic-assisted extraction (UAE) was performed, and the extracted compounds were characterized using ultra-high-pressure liquid chromatography coupled with quadrupole/time-of-flight mass spectrometry (UHPLC-QTOF-MS), molecular fluorescence and high-pressure liquid chromatography with diode-array detection (HPLC-DAD). Chemometric analysis, including parallel factor analysis (PARAFAC) and principal component analysis (PCA) explored metabolite profiles and identify patterns. PARAFAC modelling of the molecular fluorescence results revealed higher pigment content in Brazilian samples, while other countries' samples exhibited higher phenolic content. PCA modeling of HPLC-DAD results indicated that cultivated yerba mate contained higher chlorogenic acids levels, and samples from Argentina, Paraguay, and Uruguay exhibited higher concentrations of chlorogenic acids and flavonoids.

Oxidation of hydrochar produced from byproducts of the sugarcane industry for the production of humic-like substances: Characterization and interaction study with Cu(II).

Humic-like substances (HLS) are molecules extracted in an alkaline medium from different materials that have not been subjected to the natural process of humification that occurs in the soil. HLS have the potential to be used as organic fertilizers due to their ability to incorporate micronutrients such as Cu(II) and Co(II); in addition, they represent an alternative for the remediation of contaminated areas due to their high affinity for metals. HLS can be extracted from hydrochar (HC) but only with low yields of approximately 5%. Therefore, the present study aimed to increase the amount of HLS extracted from the HC produced from byproducts of the sugarcane industry through the oxidation of HC with HNO3. HLS extracted from oxidized and unoxidized HC were characterized by CHNS analysis and 13C CPMAS NMR. The interaction between HLS and Cu(II) was studied by molecular fluorescence quenching (EEM-PARAFAC) and applying the Ryan and Weber complexation model. The oxidation of HC with HNO3 allowed high yields of extracted HLS of above 80%. The oxidation carried out with 30% HNO3 for 2 h showed the best result, since the HLS30%(2h) were extracted with a very high yield (88.3%) in a short period of time. Oxidation promoted a decrease in HLS aromaticity and an increase in oxygen and nitrogen groups. HLS showed high affinity for Cu(II), as evidenced by the high logK values (between 5.5 and 5.9). HLS extracted from oxidized HCs showed higher complexation capacity due to the greater incorporation of the oxygenated groups promoted by oxidation, which are fundamental during the interaction with metallic cations. Therefore, the oxidation of HC substantially increased the production of HLS, representing a big advance for the production of carbonaceous materials with higher added value from byproducts of the sugarcane industry produced on a large scale in Brazil.

Increase of Fluorescence of Humic-Like Substances in Interaction with Cd(II): a Photoinduced Charge Transfer Approach.

Described is the enhancement of fluorescence intensity due to the interaction of a humic-like substance (HLS 1%) extracted from process water (PW) and Cd(II) ions in aqueous solution. Using Canonical Polyadic/Parallel Factor Analysis (CP/PARAFAC), two main components were seen that contributed to fluorescence, the first one increased it and the second one kept it constant in both static and dynamic fluorescence studies. Two-dimensional FTIR analysis indicated that the interaction of HLS 1% and Cd(II) ions occurred in the following order of affinity with the groups: C-O bonds in polysaccharides > C-O bonds in carboxylic acid. The results obtained suggest that the increase in fluorescence intensity and lifetime suggest a photoinduced charge transfer (PCT) between Cd(II) ions and carboxylic acid groups present in HLS 1%.

Water quality evaluation and dissolved organic matter characterization of a tropical hypereutrophic reservoir and its streams treated with Phoslock® and microbial bioremediation Enzilimp®.

Worldwide, freshwater environments are impacted by inputs of nutrients and dissolved organic matter from human activities. Yet, the recovery of aquatic systems is usually focused only on nutrient management. In our work, we presented the case of an urban and hypereutrophic environment (Pampulha reservoir, Belo Horizonte, Brazil) that receives discharges from several streams and was treated with lanthanum modified bentonite (Phoslock®) and microbial bioremediation (Enzilimp®). Our goals were to evaluate whether the treatment could improve the water quality and characterize the spatiotemporal variation of dissolved organic matter sources and indices according to absorbance and fluorescence measurements from the reservoir and streams post-application months (2018). In our results, the reservoir showed a relative decrease in its phosphorus concentration compared to data from before the treatment. On the other hand, carbon concentrations reached expressive values in the post-application months following a similar pattern found in the streams. Our data showed that the reservoir's high resistance in its hypereutrophic condition was related to the elevated loading of external inputs coming from the streams. The parallel factor analysis (PARAFAC) identified four main carbon sources, two of them being potential tracers of organic pollution in the Pampulha reservoir and watershed, together with absorbance and fluorescence indices. Our findings suggest that carbon parameters can be essential tools to provide adequate monitoring and optimization of water recovery attempts in complex, polluted environments.

Rapid determination of three textile surfactants in environmental samples by modeling excitation-emission second-order data with multi-way calibration methods.

The textile industry is an important potential source of environmental pollution due to the use of chemical products. Dyes, hydrolyzed dyes, and surfactants, among others, are chemical compounds present in wastewater of textile plant. Moreover, the anionic surfactants have toxic effects for various aquatic organisms even in low concentrations. The methodologies investigated to quantify surfactants, in general, consume a lot of analysis time and frequently use toxic or environmentally objectionable reagents. For these reasons, the objective of this work was to develop a quick and simple method to quantify surfactants without the use of expensive reagents and equipment, avoiding extraction and preconcentration stages. The proposed method is based on fluorescent spectroscopy measurements for the acquisition of second-order data in excitation-emission matrices and multivariate calibration techniques applied to the data. The unfolded partial least squares combined to residual bilinearization (U-PLS/RBL) algorithm was better than parallel factor analysis (PARAFAC). U-PLS/RBL accurately quantified alkylnonylphenolethoxylated (APEO), dodecylbenzenesulfonic acid (ADBS), and 2-phenoxy-ethoxylated fatty alcohol (AGFE) surfactants. The chemometric model obtained good analytical figures of merit: REP% between 5 and 13 and LOQ between 0.45 and 2.77 µg mL-1. This methodology had no significant difference compared with results obtained by a HPLC-FD reference technique, in addition with a considerable reduction in analysis time, reagent consumption, and therefore lower cost. For environmental applications, APEO, ADBS, and AGFE were quantify in textile wastewater treatment and in the receiving water body. The concentrations varied from 8.73 to 73.94 µg mL-1 in the textile wastewater and were not detected in the receiving water body.

Physicochemical properties of the dissolved organic carbon can lead to different physiological responses of zebrafish (Danio rerio) under neutral and acidic conditions.

Previous studies have suggested that the capacity of natural dissolved organic carbon (DOC) molecules to interact with biological membranes is associated with their aromaticity (SAC340 ); origin (allochthonous versus autochthonous, FI); molecular weight (Abs254/365 ); and relative fluorescence of DOC moieties (PARAFAC analysis). These interactions may be especially important when fish are challenged by acidic waters, which are known to inhibit the active uptake of Na+ and Cl- , while stimulating diffusive ion losses in freshwater fishes. Therefore, zebrafish were acclimated (7 days, pH 7.0) to five natural DOC sources (10 mg C/L), two from the Amazon Basin and three from Canada, together with a "no-added DOC" control. After the acclimation, fish were challenged by exposure to acidic water (pH 4.0) for 3 h. Osmoregulatory parameters were measured at pH 7.0 and 4.0. Acclimation to the five DOC sources did not disturb Na+ , Cl- and ammonia net fluxes, but resulted in differential elevations in Na+ , K+ ATPase and v-type H+ ATPase activities in fish at pH 7.0. However, after transfer to pH.4.0, the control fish exhibited rapid increases in both enzymes. In contrast the DOC- acclimated animals exhibited unchanged (Na+ , K+ ATPase) or differentially increased (v-type H+ ATPase) activities. Na+ , Cl- and ammonia net fluxes remained unchanged in the control fish, but were differentially elevated in most of the DOC treatments at pH 4.0, relative to the same DOC treatments at pH 7.0. Correlations between the osmoregulatory data the DOCs properties highlight that the DOC properties drive different effects on gill physiology.

Attenuated total reflectance Fourier transform (ATR-FTIR) spectroscopy and chemometrics for organic cinnamon evaluation.

Organic food consumption has increased significantly over time. This contributes to the increased demand and price of this kind of food. Among the organic products, cinnamon stands out for its characteristic flavor and bioactive compounds. Thus, the work aimed to verify the potentials of attenuated total reflectance Fourier transform mid-infrared spectroscopy (ATR-FT-MIR) coupled with Parallel Factor Analysis (PARAFAC) for evaluation of cinnamon organic samples. As result, the proposal is feasible in the differentiation of organic cinnamon powder, in which ATR-FT-MIR coupled with PARAFAC showed the differentiation of organic from non-organic ones on the scores mode, the precision at repeatability level on one loading mode, and the spectral region, on the other loading mode, above 2600 cm-1 was related to the differentiation of the organic and non-organic samples.

Determination of melamine in milk by fluorescence spectroscopy and second-order calibration.

Melamine is a compound commonly used in the manufacturing of plastic and flame retardant products, but due to its solubility on water and high nitrogen content, it is also used to adulterate milk to mask adulteration by dilution in protein content tests. This work proposes a quick method using excitation-emission matrix (EEM) fluorescence spectroscopy and second-order calibration methods (PARAFAC and U-PLS/RBL) for the identification and quantification of melamine in milk. The proposed method uses a single clean-up step with acetic acid, resulting in a quick, low-cost, and environmentally friendly procedure, in agreement with green chemistry principles. Both PARAFAC and U-PLS/RBL were capable of detecting melamine in milk above 120.6 and 146.5 ppm respectively, adequate for adulterations above 2% in volume, with RMSEPs of 68.6 and 81.9 ppm, respectively.

Oil spill in northeastern Brazil: Application of fluorescence spectroscopy and PARAFAC in the analysis of oil-related compounds.

Between November 2019 and February 2020, 53 water samples were collected along 430 km of coastline in northeastern Brazil, which was the location of an oil spill that occurred in August 2019. Synchronous fluorescence matrices (SFMs) were acquired to avoid regions affected by Raman Stokes scatterings and second harmonic signals, and then, the SFMs were converted into excitation-emission matrices (EEM) by shear transformation. The matrix coupled with parallel factor analysis (PARAFAC) was used in the study of fluorescent components present in the collected waters. A sample collected before the oil spill and another from Florianópolis-SC, 2000 km from the incident, were used as references for nonimpacted waters. In the postspill samples, 4 components were determined, with component 1 (λexc = 225 nm, λem = 475 nm) being associated with humic-like organic matter (terrestrial), component 2 (λexc = 230 nm, λem = 390 nm) being associated with humic-like organic matter (marine), component 3 (λexc = 225/295 nm, λem = 345 nm) being associated with dibenzothiophene-like components also observed in tests with crude oil samples, and component 4 (λexc = 220/280 nm, λem = 340 nm) being associated with a naphthalene-like substance. Principal component analysis (PCA) was performed on the PARAFAC scores. The distribution of samples along the 4 components was observed and compared with the reference samples.

N-Way NIR Data Treatment through PARAFAC in the Evaluation of Protective Effect of Antioxidants in Soybean Oil.

The use of chemometric tools is progressing to scientific areas where analytical chemistry is present, such as food science. In analytical food evaluation, oils represent an important field, allowing the exploration of the antioxidant effects of herbs and seeds. However, traditional methodologies have some drawbacks which must be overcome, such as being time-consuming, requiring sample preparation, the use of solvents/reagents, and the generation of toxic waste. The objective of this study is to evaluate the protective effect provided by plant-based substances (directly, or as extracts), including pumpkin seeds, poppy seeds, dehydrated goji berry, and Provençal herbs, against the oxidation of antioxidant-free soybean oil. Synthetic antioxidants tert-butylhydroquinone and butylated hydroxytoluene were also considered. The evaluation was made through thermal degradation of soybean oil at different temperatures, and near-infrared spectroscopy was employed in an n-way mode, coupled with Parallel Factor Analysis (PARAFAC) to extract nontrivial information. The results for PARAFAC indicated that factor 1 shows oxidation product information, while factor 2 presents results regarding the antioxidant effect. The plant-based extract was more effective in improving the frying stability of soybean oil. It was also possible to observe that while the oxidation product concentration increased, the antioxidant concentration decreased as the temperature increased. The proposed method is shown to be a simple and fast way to obtain information on the protective effects of antioxidant additives in edible oils, and has an encouraging potential for use in other applications.

Fulvic acids from Amazonian anthropogenic soils: Insight into the molecular composition and copper binding properties using fluorescence techniques.

Fulvic acids (FA) are one of the components of humic substances and play an important role in the interaction with metallic species and, consequently, the bioavailability, distribution and toxicity of metals. However, only a few studies have investigated these FA properties in specific environment, such as anthropogenic soils. Therefore, knowledge about FA molecular composition as well as the FA-metal interaction is essential to predict their behavior in the soil. For this reason, the aim of this study was to investigate the molecular composition of FA extracted from two sites in an anthropogenic soil (Terra Mulata), from the Amazon region, as well as their interactions with Cu(II) ions as a model. Results from 13C NMR, infrared and elemental analysis showed that these FA are composed mostly by alkyl structures and oxygen-functional groups, e.g., hydroxyl, carbonyl and carboxyl. The interaction with Cu(II) ions was evaluated by fluorescence quenching, in which the FA showed both high quantity of complexing sites per gram of carbon and good affinity to interact with the metal when compared with other soil FA. The results showed that the complexation capacity was highly correlated by the content of functional groups, while the binding affinity was largely influenced by structural factors. In addition, through the lifetime decay given by time-resolved fluorescence, it was concluded that static quenching took place in FA and Cu(II) interaction with the formation of a non-fluorescent ground-state complex. Therefore, this fraction of soil organic matter will fully participate in complexation reactions, thereby influencing the mobility and bioavailability of metal in soils. Hence, the importance of the study, and the role of FA in the environment, can be seen especially in the Amazon, which is one of the most important biomes in the world.

Effects of natural light and depth on rates of photo-oxidation of dissolved organic carbon in a major black-water river, the Rio Negro, Brazil.

Systems rich in terrigenous dissolved organic carbon (DOC), like the Rio Negro, can contribute significant amounts of carbon dioxide back to the atmosphere and support important microbial communities. We investigated photo-oxidation in the Rio Negro: (1) the depth to which light causes complete photo-oxidation to CO2 and changes in DOC structure, (2) the daily rate of change of absorbance indices, (3) the relationship between sub-surface rates of photo-oxidation to CO2 and light exposure, (4) the areal rates of photo-oxidation, and (5) the stability of fluorophore signals. Experiments were run in an outdoor pool of Rio Negro water, under natural sunlight during the dry seasons of 2015 and 2018. In 2018, rates of complete photo-oxidation and changes in absorbance indices decayed exponentially, approaching their asymptotes between 9 and 15 cm depth. In 2015, direct absorbance indices ceased changing at 14 cm depth. Fluorescence of humic acid-like moieties continued to decrease, sometimes to 35-43 cm depth. This indicates that partial photo-oxidation of DOC, and thus interaction with the microbial community, occurs to greater depths than previously expected. Areal rates of CO2 production were 28.8 and 39.3 mg C m-2 d-1 (two experiments, October 2018). Sub-surface (1.1 cm) rates were strongly related to light levels, reaching a maximum of 0.68 mg C l-1 d-1 in September. Complete photo-oxidation ceased below 29.6 mW cm-2 d-1 UV radiation, providing a daily baseline for observable production of CO2. Absorbance indices changed by 9 to 14% d-1 at high light levels, except for R254/365 (4.4% d-1). Fluorophore emission ranges were stable between 2014 and 2018, indicating that emissions can be compared across time and space. This study contributes to better estimates and understanding of photo-oxidation in tropical, black-water rivers, which will be useful for carbon modelling.

PARAFAC HPLC-DAD metabolomic fingerprint investigation of reference and crossed coffees.

In this study two cultivars of Coffea arabica L., Bourbon (reference) and IPR101 (crossing) were analyzed. The extracts were prepared according to a simplex centroid design with four components, ethanol, ethyl acetate, dichloromethane, and hexane. Multiway data were obtained by HPLC-DAD analysis of the fifteen different mixtures for each cultivar. The PARAFAC methodology was used to investigate the chromatographic fingerprint. For both cultivars, Factor 1 was able to discriminate mixtures containing ethyl acetate as solvent. Factor 2 indicated that mixtures in pure ethanol and binary mixtures containing ethanol were the most efficient in extracting chlorogenic acids and factor 3 identified methylxanthines through spectrophotometric profile in all mixtures. Higher concentrations were obtained by the ethanol, dichloromethane and hexane ternary mixture for the Bourbon cultivar and by the quaternary mixture of these solvents with ethyl acetate for the IPR101 cultivar. Trigonelline and cafestol were extracted in both cultivars. The reference coffee showed higher relative abundances of cafestol ester, chlorogenic acids and trigonelline whereas the crossed coffee showed higher levels of caffeine. To confirm these results, UPLC-MS was used as a complementary method to confirm the presence of the metabolites in these extracts. The three way PARAFAC strategy determines correlations of HPLC-DAD chromatographic and spectral data simultaneously with samples permitting a more unambiguous assignment of metabolic groups than can be obtained treating chromatographic and spectral data separately by two way methods. This can provide higher quality chromatographic fingerprints for food chemistry.

Biochar feedstock and pyrolysis temperature effects on leachate: DOC characteristics and nitrate losses from a Brazilian Cerrado Arenosol mixed with agricultural waste biochars.

Dissolved organic carbon (DOC) leached from Brazilian Cerrado Arenosols can lead to carbon (C) losses and lower soil fertility, while excessive nutrient, e.g. nitrate (NO3-), leaching can potentially cause water contamination. As biochar has been shown to stabilize C and retain soil nutrients, a greenhouse experiment was conducted to test different biochars' contributions to DOC and NO3- leaching from a sandy soil. Biochars were made from four local agricultural waste feedstocks (cotton residue, swine manure, eucalyptus sawmill residue, sugarcane filtercake) pyrolysed at 400, 500 and 600 °C. Biochar was mixed with soil at 5% weight in pots and maize seeds planted. Leachate was collected weekly for six weeks and analyzed for DOC and NO3- concentrations, while fluorescence spectroscopy with parallel factor analysis (PARAFAC) was used to interpret DOC characteristics. Cotton and swine manure biochar treatments had higher DOC and NO3- losses than eucalyptus biochar, filtercake biochar, and control treatments. Cotton and swine manure biochar treatments at high temperatures lost mostly terrestrial, humified DOC, while swine manure, filtercake, and eucalyptus biochars at low temperatures lost mostly labile, microbially-derived DOC. Through the practical use of fluorescence spectroscopy, our study identified filtercake and eucalyptus biochars as most promising for retaining DOC and NO3- in a Cerrado Arenosol, potentially reducing stable C and nutrient losses.