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Multivariate curve resolution has been applied to both simulated and experimental data sets where high or even complete overlapping occurs between component profiles in one data mode. It is shown that rotational ambiguity exists in the bilinear decomposition of the augmented data matrices built with second-order data for pure analyte standards and test samples containing uncalibrated interferents. However, even in the presence of rotational ambiguity, initialization based on the so-called purest variables in one of the data modes may allow one to develop analytical protocols with reasonable statistical indicators for the prediction of the analyte of interest. In one of the explored experimental systems, the analyte ciprofloxacin was determined in the presence of the interferent salicylate, measuring time decay-luminescence matrix data. The average prediction error was 0.02 mg L−1 in the test set, corresponding to a relative error of ca. 8%. In the second system, capillary electrophoresis with UV detection was employed to determine ciprofloxacin in aqueous samples in the presence of other fluoroquinolones, achieving analyte recoveries in the range 101–113%. Although further theoretical work may still be needed, the present analysis of the feasible component profiles after bilinear decomposition provides some clues to interpret the phenomenon. Image 1 • Multivariate curve resolution is applied to second-order data. • Strong or complete overlapping in one data mode is considered. • Rotational ambiguity is assessed. • Simulated and experimental data are studied. • Prediction results are analyzed depending on initialization and constraints. [ABSTRACT FROM AUTHOR]

Abstract: The performance of MCR-ALS was studied in the modeling of non-linear kinetic-spectrophotometric data acquired by a stopped-flow system for the quantitation of tartrazine in the presence of brilliant blue and sunset yellow FCF as possible interferents. In the present work, MCR-ALS and U-PCA/RBL were firstly applied to remove the contribution of unexpected components not included in the calibration set. Secondly, a polynomial function was used to model the non-linear data obtained by the implementation of the algorithms. MCR-ALS was the only strategy that allowed the determination of tartrazine in test samples accurately. Therefore, it was applied for the analysis of tartrazine in beverage samples with minimum sample preparation and short analysis time. The proposed method was validated by comparison with a chromatographic procedure published in the literature. Mean recovery values between 98% and 100% and relative errors of prediction values between 4% and 9% were indicative of the good performance of the method. [Copyright &y& Elsevier]

Highlights • Quantitation of organophosphorus pesticide pirimiphos-methyl in maize grains. • Fluorescence enhancement by inclusion of the target analyte in surfactant micelles. • Development of a simple and efficient extraction procedure. • Chemometric strategy to overcome matrix effect. Abstract A novel method for the determination of pirimiphos-methyl (PMM) in maize grains by fluorescence spectroscopy and three-way calibration was developed. The formation of supramolecular complexes and their effect on the luminescence properties of PMM were studied. A solvent extraction step followed by solid phase extraction for sample clean-up was optimized. A chemometric approach consisting in PARAFAC as second-order data processing tool and piecewise direct standardization (PDS) for reducing the complexity of the calibration process was developed to overcome the matrix effect. This strategy allowed dealing with the matrix effect while reducing the number of samples to be processed and, consequently, the solvent consumption and the total analysis time. Finally, three-way calibration was applied to predict the PMM concentration in unknown samples. The mean recovery was 115% and the limits of detection and quantitation were in the order of the parts per trillion, i.e. 6 and 20 ng g−1, respectively. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Development of two extraction method for six veterinary drugs in eggs. • Experimental design and desirability function implementation. • Analysis of both the solvent effect and the matrix effect during the extraction. Abstract Two extraction strategies for albendazole, chloramphenicol, trimethoprim, enrofloxacin, oxitetracycline and nicarbazin in egg were optimized for its quantitation by liquid chromatography. First, two designs were built to find out the optimized condition for the air assisted-dispersive liquid-liquid microextraction based on solidification of organic drop: a fractional factorial and a central composite design. The optimum conditions were 1140 µL of water, 125 mg of ZnSO 4 , 1175 µL of acetonitrile, 1200 µL of methyl alcohol and 740 µL of propanone, using 1.00 g of homogenized egg and 50 µL of 1-dodecanol. Second, two designs were also built to optimize the dispersive liquid-liquid microextraction: a central composite design and a mixture design to set the combination of the re-suspended solvents. The optimum conditions were 1840 μL of acetonitrile and 160 μL of dichloromethane and the re-suspended mixture consisting in acetonitrile and sodium phosphate buffer 10 mmol L−1 pH = 3.50 (30:70 v/v). [ABSTRACT FROM AUTHOR]

An application of four-way multivariate calibration for the quantitation of azinphos-methyl (AZM) in fruits is presented. The known photochemically induced degradation of AZM into a highly fluorescent product was exploited for the generation of third-order data with quantitative purpose. The data generation consisted in the measurement of excitation-emission fluorescence matrices at different times after UV-light irradiation. For this purpose, a reactor was built connecting an external UV-light source through an optical fiber to the sample holder. The data were modelled with two algorithms, PARAFAC and U-PLS/RTL. The second-order advantage was exploited in the analysis of samples containing un-modelled components and an improvement in the analytical figures of merit was observed as long as the data dimensions were increased. The method was successfully applied to the quantitation of AZM in apple, pear and peach juice samples with and without spiked analyte. The limits of detection were of 3.6 μg L −1 in aqueous solution and 21–66 μg L −1 in fruit juice samples. [ABSTRACT FROM AUTHOR]

• Implementation of a HPLC-DAD method for the determination of enrofloxacin in egg. • Analysis of the presence of enrofloxacin in white egg, egg yolk, and lyophilized samples. • Study of the long-term administration of ENR (100 days) to laying hens on the characteristic of the eggs. • Analysis of the consumer exposure assessment after the intake of lyophilized samples. The use of the antibiotic enrofloxacin (ENR) in poultry is controversial. A high‐performance liquid chromatography coupled to fast‐scanning fluorescence detection (HPLC - FSFD) method for the determination of ENR in egg white, egg yolk, and lyophilized samples was developed. In a first analysis, the long-term administration of ENR (100 days) to laying hens was carried out to determine its presence in egg white, yolk, or both. The predominance of ENR was observed in egg white and variations in the weight of egg white and eggshell was evidenced, showing a potential problem in the industry. Eventually, the presence of ENR was confirmed in commercial lyophilized egg white samples in concentration values around 350 µg kg−1. The consumer exposure assessment was estimated for children, adolescents, and adults. The result displayed that, in an intake of lyophilized egg white with food-producing animals, the %ADI exceeds 100%, showing toxicological levels. [ABSTRACT FROM AUTHOR]

A low-level data fusion strategy was developed and implemented for data processing of second-order liquid chromatographic data with dual detection, i.e. absorbance and fluorescence monitoring. The synergistic effect of coupling individual information provided by two different detectors was evaluated by analyzing the results gathered after the application of a series of data preprocessing steps and chemometric resolution. The chemometric modeling involved data analysis by MCR-ALS, PARAFAC and N-PLS. Their ability to handle the new data block was assessed through the estimation of the analytical figures of merits achieved in the prediction of a validation set containing fifteen fluorescent and non-fluorescent veterinary active ingredients that can be found in poultry litter. Eventually, the feasibility of the application of the fusion strategy to real poultry litter samples containing the studied compounds was verified. [ABSTRACT FROM AUTHOR]

The ecological risks posed by two β-diketone antibiotics (DKAs, enrofloxacin, ENR and ciprofloxacin, CPX), characterized by their long persistence in aqueous environments and known deleterious effect on model organisms such as zebrafish were analysed using Rhinella arenarum larvae. Sublethal tests were conducted using environmentally relevant concentrations of both ENR and CPX (1–1000 μg L −1 ) under standard laboratory conditions for 96 h. Biological endpoints and biomarkers evaluated were body size, shape, development and growth rates, and antioxidant enzymes (glutathione-S-transferase, GST; Catalase, CAT). Risk assessment was analysed based on ration quotients (RQ). The size and shape measurements of the larvae exposed to concentrations greater than 10 μg L −1 of CPX were lower compared to controls (Dunnett post hoc p < 0.05) and presented signs of emaciation. Concentrations of 1000 μg L −1 of CPX induced GST activity, in contrast with inhibited GST and CAT of larvae exposed to ENR. Risk assessments indicated that concentrations greater than or equal to10 μg L −1 of CPX and ENR are ecotoxic for development, growth, detoxifying, and oxidative stress enzymes. It is suggested that additional risk assessments may provide evidence of bioaccumulation of CPX and ENR in tissues or organs of amphibian larvae by mesocosm sediment test conditions. Finally, intestinal microbiome studies should be considered to establish the mechanisms of action of both antibiotics. [ABSTRACT FROM AUTHOR]

Antiretrovirals are pharmaceuticals used in the treatment of the human immunodeficiency virus; they are contaminants of emerging concern that have received considerable attention in recent decades due to their potential negative environmental effects. Data on the bioaccumulation and possible environmental risks posed by these drugs to aquatic organisms are very scarce. Therefore, the aim of this study was to evaluate the bioaccumulation of abacavir and efavirenz in Rhinella arenarum tadpoles subjected to acute static toxicity tests (96 h) at environmentally relevant concentrations. The analytical procedure consisted of the development and optimization of a method involving ultra-high performance liquid chromatography with tandem mass spectrometry detection. The instrumental conditions, optimized by design of experiments using the response surface methodology, yielded limits of detection of 0.3 μg L−1 for abacavir and 0.9 μg L−1 for efavirenz; and limits of quantification of 1.9 μg L−1 for abacavir and 5.6 μg L−1 for efavirenz. Subsequently, the bioaccumulation of the pharmaceutical drugs in tadpoles was evaluated at three exposure concentrations. Efavirenz displayed the highest bioaccumulation levels. This study shows the bioaccumulation potential of abacavir and efavirenz in amphibian tadpoles at exposure concentrations similar to those already detected in the environment, indicating an ecological risk for R. arenarum and probably other aquatic organisms exposed to these drugs in water bodies. [Display omitted] • Assessment of bioaccumulation of the antiretrovirals abacavir and efavirenz on Rhinella arenarum tadpoles. • Development of acute static toxicity tests (96 h) at concentration levels expected to be found in the environment. • Development and optimization of a method involving UHPLC-MS/MS. • Optimization of the MS detection to reach high sensitivity by Design of Experiments. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate the bioaccumulation and toxicological effects of four antiretrovirals (lamivudine, stavudine, zidovudine and nevirapine) on Rhinella arenarum tadpoles, after short-term (48 h) exposure to these drugs at sublethal concentrations. The analytical procedure involved a simple extraction method followed by ultra-high performance liquid chromatography with diode array detection and chemometric analysis for data processing. Under the conditions studied, the analytes investigated, particularly nevirapine, showed possible bioaccumulation in tadpoles. Besides, an increase in the bioaccumulation was observed when increasing the exposure concentration. In addition, the enzymatic biomarkers measured to evaluate the toxicological effects showed that acethylcholinesterase activity was similar to that of the control group, while glutathione S-transferase activity was increased, indicating potential oxidative stress damage. Our results also allowed demonstrating the usefulness of chemometric algorithms to quantitate analytes in complex matrices, such as those absorbed by tadpoles in aquatic ecosystems. The results also evidenced the short-term antiretroviral bioaccumulation in tadpoles and the alteration of antioxidant systems, highlighting the need of environmental studies to elucidate the ecotoxicological risk of antiretrovirals in humans and wildlife. Image 1 • Short-term exposure of R. arenarum tadpoles to four antiretrovirals. • Evidence of bioaccumulation and toxicological effects. • Highest bioaccumulation level for nevirapine. • Glutathione S-transferase as a useful biomarker of oxidative stress in tadpoles exposed to antiretrovirals. [ABSTRACT FROM AUTHOR]