Multiphase electroextraction of malachite green from surface water and its determination using digital imaging and chemometric tools.

This study introduces a novel method for the quantification of malachite green (MG), a pervasive cationic dye, in surface water by synergizing multiphase electroextraction (MPEE) with digital image analysis (DIA) and partial least square discriminant analysis. Aimed at addressing the limitations of conventional DIA methods in terms of quantitation limits and selectivity, this study achieves a significant breakthrough in the preconcentration of MG using magnesium silicate as a novel sorbent. Demonstrating exceptional processing efficiency, the method allows for the analysis of 10 samples within 20 min, exhibiting remarkable sensitivity and specificity (over 0.95 and 0.90, respectively) across 156 samples in both training and test sets. Notably, the method detects MG at low concentrations (0.2 µg L-1) in complex matrices, highlighting its potential for broader application in environmental monitoring. This approach not only underscores the method's cost-effectiveness and simplicity but also its precision, making it a valuable tool for the preliminary testing of MG in surface waters. This study underscores the synergy among MPEE, DIA, and chemometric tools, presenting a cost-efficient and reliable alternative for the sensitive detection of water contaminants.

Use of pulp, peel, and seed of Annona crassiflora Mart. in elaborating extracts for fingerprint analysis using paper spray mass spectrometry.

The Brazilian cerrado is considered one of the most critical biomes in the world. Araticum (Annona crassiflora Mart.) is a native plant from the Brazilian cerrado, abundant in nutrients and highly energetic. This study aimed to obtain chemical fingerprints of different parts of the araticum fruit, i.e. pulp, peel, and seed. Extracts from these three parts were prepared using different solvents (ethanol, water, and mixtures of ethanol and water) and later analyzed by paper spray ionization mass spectrometry. In general, ethanol extracted more metabolites than the other solvents. The chemical profiles varied according to the fruit part, geographic location, and extractor solvent. Among the metabolites, acetogenins (62.3%) and alkaloids (20.7%) predominated. Principal component analyses revealed that the samples were grouped according to the fruit part, regardless of the extractor solvent used. Araticum shows remarkable potential due to the beneficial properties of the metabolites for human health. The insertion of araticum in the human diet is still underexplored but is a promising alternative.

Screening method for the rapid detection of diethylene glycol in beer based on chemometrics and portable near-infrared spectroscopy.

A recent case of contamination of some batches of a Brazilian beer brand with diethylene glycol (DEG) had great repercussion, resulting in at least seven deaths. In this article, a direct method was developed for the rapid detection of DEG in beer samples based on portable near-infrared spectroscopy combined with partial least squares discriminant analysis (PLS-DA). The discriminant model was built with 100 uncontaminated beer samples and 100 samples containing DEG in a concentration range between 10 and 1000 mg L-1, totalizing 200 samples of different brands and styles. The method was validated by estimating figures of merit, such as false positive and false negative rates, sensitivity, specificity, accuracy, accordance, and concordance. The decision limit (CCα) of the method was 52 mg L-1 and the detection capability (CCß) was 106 mg L-1. This method does not consume reagents/solvents and can be suitable for the beer industry quality control or forensic investigations.

Detection of adulterations in a valuable Brazilian honey by using spectrofluorimetry and multiway classification.

Spectrofluorimetry combined with multiway chemometric tools were applied to discriminate pure Aroeira honey samples from samples adulterated with corn syrup, sugar cane molasses and polyfloral honey. Excitation emission spectra were acquired for 232 honey samples by recording excitation from 250 to 500 nm and emission from 270 to 640 nm. Parallel factor analysis (PARAFAC), partial least squares discriminant analysis (PLS-DA), unfolded PLS-DA (UPLS-DA) and multilinear PLS-DA (NPLS-DA) methods were used to decompose the spectral data and build classification models. PLS-DA models presented poor classification rates, demonstrating the limitation of the traditional two-way methods for this dataset, and leading to the development of three-way classification models. Overall, UPLS-DA provided the best classification results with misclassification rates of 4% and 8% for the training and test sets, respectively. These results showed the potential of the proposed method for routine laboratory analysis as a simple, reliable, and affordable tool.

Large-volume electric field-assisted multiphase extraction of malachite green from water samples: A multisample device and method validation.

In this work, a new large-volume multiphase, multi-sample electroextraction device was developed and applied to selectively extract malachite green (MG) from water samples. This device was easily constructed with ordinary materials and capable of extracting ten samples simultaneously, obtaining MG preconcentrated on a solid support, to fit into a pipette tip. A multi-well plate was applied to extract MG from aquaculture water samples, and the extracts containing the desorbed MG were analysed by LC-DAD and LC-MS/MS. The signals from both detectors were used in two independent validation procedures. Linearity, matrix effect, selectivity, precision, trueness, and limits of detection and quantification were all evaluated. For both detectors, linearity was demonstrated in the range of 0.5-5 µg L-1 (R2 > 0.98). Matrix effect was insignificant for LC-DAD only, and the average preconcentration factor was about 60 times. Recoveries ranged from 94 to 113% for LC-DAD and 95-115% for LC-MS/MS analysis. ANOVA was applied to estimate the standard deviation under repeatability (6.96-8.61% for LC-DAD and 5.98-7.41% for LC-MS/MS) and within-reproducibility (6.96-8.61% for LC-DAD and 6.56-7.41% for LC-MS/MS) conditions. The limits of detection and quantification for LC-MS/MS analysis were 4.29 and 28.74 ng L-1, respectively, while, for LC-DAD, these limits were 14.29 and 95.81 ng L-1, respectively. The results demonstrated that the developed method was suitable for determining MG in water samples, and the large-volume multiphase, multi-sample electroextraction device proved to be a powerful sample preparation technique to obtain high clean-up and large preconcentration levels, which are of paramount importance for environmental applications.

Development and Evaluation of a 66-Well Plate Using a Porous Sorbent in a Four-Phase Extraction Assisted by Electric Field Approach.

In this work, cellulose cone tips were used as a hydrophilic sorbent supporting an aqueous electrolyte solution in a four-phase electric-field-assisted extraction. The wetted tips were immersed in an immiscible organic phase, acting as a filter to extract analytes present in an aqueous sample. Simultaneous four-phase extractions were carried out under the influence of an electric field using a 66-well plate constructed with inexpensive and readily available laboratory materials. Several parameters that control the electric resistivity of the system were evaluated, and the cone tips provided reproducible and stable electric current during application of electric potential difference. In a final application, a cationic dye and its metabolite, crystal and leuco crystal violet, were extracted from spiked fish extracts and quantified by a digital image analysis method. The method presented a linear range of 2-100 ng mL-1 ( r > 0.999), limit of detection of 1.37 ng mL-1, inter- (3 consecutive days) and intraday precision determined for 4 concentration levels ( n = 6, each) were lower than 29% and mean recoveries for these concentrations ranging from 95% to 115%. The results demonstrated that the 66-well plate provides a stable, reproducible, and simple way to conduct extractions of ionic compounds from complex aqueous matrixes. The effectiveness of the low-cost cellulose cone tips used as a solid fourth phase also confirmed that it can easily overcome many drawbacks of similar liquid-liquid-liquid approaches.

Attenuated Total Reflectance Fourier Transform Spectroscopy (ATR-FTIR) and chemometrics for discrimination of espresso coffees with different sensory characteristics.

Coffee cup quality, determined by the sensory attributes evaluated by professional tasters, is a decisive factor for evaluating coffee, with the "Specialty Coffee Association of America" (SCAA) classification being nowadays considered the most suitable. Panels of trained coffee tasters are used by the industry to describe and evaluate beverage quality, but those evaluations can be subjective and time demanding. Recent studies have demonstrated the potential of spectroscopy-based methods for establishing parameters of quality in the analysis of food products, including coffee. Thus, the aim of this study was to evaluate the potential of ATR-FTIR and chemometrics to discriminate espresso coffees with different sensory characteristics reported by a panel of coffee tasters. The results showed good consistency among coffee tasters. PLS-DA models based on spectroscopic data were able to classify samples according to sensory attributes, confirming the potential of FTIR and chemometrics in coffee quality evaluation.