Assessing the environmental pesticides impact of river sediments from a basin in western Mexico: Spatiotemporal distribution, risk assessment of aquatic invertebrates and pesticides prioritization.

The intensive use of pesticides in Mexican agriculture has contributed significantly to the increase in food production, but at the same time represents potential risk to biota. This situation creates a dilemma between the need to increase food production and the preservation of the environment and human health. Aquatic invertebrates play a vital role in the balance of aquatic ecosystems but are sensitive to pesticides contamination. The sensitivity of aquatic invertebrates to pesticides contamination has led them to be used to assess the potential impact of this contamination on aquatic ecosystems. In the present study, conducted in the Ayuquila-Armería basin, the following aims were achieved: 1) quantifying the presence of 20 pesticides in river sediments, 2) assessing the spatiotemporal distribution of pesticides in river sediments, 3) determining the potential risk to aquatic invertebrates, and 4) prioritizing pesticides based on their potential risk. Twelve pesticides were consistently quantified in 192 river sediments samples. The pesticides with the highest concentrations were ametrine, malathion and picloram. The temporal analysis showed seasonality in pesticide concentrations, with higher detection frequencies during the wet season. The risk assessment showed that aquatic invertebrates may be affected by the concentrations of carbofuran, malathion, diazinon and ametrine. Pesticides prioritization identified ametrine, carbofuran, and diazinon as major concerns based on the methodology that considers the Frequency and Extent of Exceedance. This study provides valuable insights into the current pesticides scenario in the Ayuquila-Armería River sediments. The findings underscore the need for sustainable alternatives to mitigate the ecological risks associated with pesticides contamination in this aquatic ecosystem.

Occurrence and temporal distribution of oxandrolone and meclizine in surface water, sediments, fish muscle and otter feces of the Ayuquila-Armería basin, Mexico.

Aquatic ecosystems worldwide are strongly influenced by the productive activities of a region. These activities can generate pollution by compounds with little-known or unknown characteristics and without regulation. Emerging contaminants are a group of compounds that have worldwide begun to be frequently detected in the environment, raising concern about their possible adverse effects on human and environmental health. Thus, it is important to generate a broader panorama of the dissemination of contaminants of emerging concern in the environment, implement actions to regulate their usage. This study aims to evaluate the occurrence and temporal distribution of oxandrolone and meclizine in surface water, sediments, tilapia muscle, and otter feces of the Ayuquila-Armería river, Mexico. Oxandrolone was detected in 55 % of the total analyzed samples, while meclizine was present in 12 %. In surface water, oxandrolone was present in 56 % of the samples, while meclizine in 8 %. In sediments, oxandrolone was detected in 45 % and meclizine was not detected. In tilapia muscle, oxandrolone was present in 47 % of samples and meclizine was not detected. In otters feces samples, oxandrolone and meclizine were present in 100 %. Regardless of the season (wet or dry), oxandrolone was detected in all four sample types, while meclizine was only detected in surface water and otter feces samples. Oxandrolone in the aquatic ecosystem of the Ayuquila-Armería basin showed that season variation generates a significant effect on their concentrations, especially in surface water and sediments. Meclizine did not show temporal variations either in seasons or between years. Particularly, oxandrolone concentrations presented an influence with respect to the sites that present continuous residual discharges to the river. In this sense, this study could be considered as a starting point for further routine monitoring of emerging contaminants to support regulation policies regarding their use and disposal.

Development of a rapid, high-sensitivity, low-cost fluorescence method for protein surface hydrophobicity determination using a Nanodrop fluorospectrometer.

A microvolumetric method for surface hydrophobicity (H0) determination of proteins using a Nanodrop fluorospectrometer was developed. This method reduces the protein and fluorophore quantities that are necessary for sample preparations and readings by two and three orders of magnitude, respectively, compared to conventional methods. In addition, readings can be obtained in just 2-6 s. Bovine serum albumin (BSA) and 1-anilino 8-naphthalene sulfonic acid (ANS) were used for the first optimization of appropriate fluorophore-protein conditions for H0 determination (20 µM ANS, 0.5-4 µM BSA, pH 5). Based on validation guidelines, the novel method shows linear behavior, good intraday precision, accuracy, and sensitivity. This method was robust against several factors, as determined by a Youden-Steiner test. Additional surface hydrophobicity determinations using several proteins demonstrate suitable method applicability. The present microvolumetric method provides a reliable technique to determine the H0 of proteins for pharmaceutical, biotechnological, and food applications.

Hollow fiber liquid-phase microextraction combined with supercritical fluid chromatography coupled to mass spectrometry for multiclass emerging contaminant quantification in water samples.

The hollow fiber liquid-phase microextraction allows highly selective concentration of organic compounds that are at trace levels. The determination of those analytes through the supercritical fluid chromatography usage is associated with many analytical benefits, which are significantly increased when it is coupled to a mass spectrometry detector, thus providing an extremely sensitive analytical technique with minimal consumption of organic solvents. On account of this, a hollow fiber liquid-phase microextraction technique in two-phase mode combined with supercritical fluid chromatography coupled to mass spectrometry was developed for quantifying 19 multiclass emerging contaminants in water samples in a total chromatographic time of 5.5 min. The analytical method used 40 µL of 1-octanol placed in the porous-walled polypropylene fiber as the acceptor phase, and 1 L of water sample was the donor phase. After extraction and quantification techniques were optimized in detail, a good determination coefficient (r2 > 0.9905) in the range of 0.1 to 100 µg L-1, for most of the analytes, and an enrichment factor in the range of 7 to 28,985 were obtained. The recovery percentage (%R) and intraday precision (%RSD) were in the range of 80.80-123.40%, and from 0.48 to 16.89%, respectively. Limit of detection and quantification ranged from 1.90 to 35.66 ng L-1, and from 3.41 to 62.11 ng L-1, respectively. Finally, the developed method was successfully used for the determination of the 19 multiclass emerging contaminants in superficial and wastewater samples.

HPLC-DAD method for the detection of five annopurpuricins in root samples of Annona purpurea.

INTRODUCTION: Annona purpurea is a species known in Mexico as "cabeza de negro". In folk medicine A. purpurea root is used to treat patients with kidney diseases and cancer. Our recent studies demonstrated that this species contains five acetogenins named annopurpuricins A-E, which are active against tumoural cell lines in a subnanomolar range. OBJECTIVE: To develop an analytical method using a high-performance liquid chromatography diode array detector (HPLC-DAD) to quantify annopurpuricins A-E in different A. purpurea root samples. METHODOLOGY: To quantify the five annopurpuricins A-E a sample treatment was carried out, which consisted of fractionation by means of cold and hot maceration; using solvents of ascending polarity: hexane, dichloromethane, methanol and water. The resulting extracts were subject to HPLC-DAD analysis. The optimised chromatographic separation on a XBRIDGE C18 column achieved separation of all compounds in around 30 min. RESULTS: The developed method was validated according to ICH (International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use) validation guide. The developed analytical method was found fast, economic, robust, sensitive, linear and precise. The dichloromethane extract of A. purpurea contains annopurpuricin A in quantities 2- to 25-fold higher than annopurpuricins B-E. This optimised method identified and quantified five annopurpuricins, highly bioactive molecules, in A. purpurea root. CONCLUSIONS: The fingerprint of the dichloromethane extracts of A. purpurea was obtained at 210 nm. The results analysis allowed to quantify annopurpuricins A-E that are present in different collection batches of medium polarity extracts. After data analysis, annopurpuricin A could be establish as the metabolite marker of the root of the species.

Validation of an HPLC-DAD method for the determination of plant phenolics

Abstract A selective, sensitive and precise reversed phase HPLC-DAD method was developed and validated for the simultaneous determination of six phenolic acids in the aqueous extract and their hydrolyzed forms prepared from Solanum elaeagnifolium Cav., Solanaceae, Ampelocissus acapulcensis (Kunth) Planch., Vitaceae, or Brosimum alicastrum Sw., Moraceae. The new method showed good linearity (r > 0.999) in a relatively wide concentration range (0.5-100 mg/l). The limits of detection and quantification for the compounds were in the range of 0.097-0.467 mg/l and 0.097-0.496 mg/l, respectively. The recoveries of compounds were calculated in three different concentrations in the range of 88.07-109.17% and matrix effect was less than 5% for all phenolic acids. Finally, our developed HPLC method is simple, reliable and successfully applied to identify and quantify the phenolic acids in complex aqueous extracts from medicinal species, that can be useful for the analysis of infusions that people consume in folk medicine.

Analytical Method for Pesticides in Avocado and Papaya by Means of Ultra-High Performance Liquid Chromatography Coupled to a Triple Quadrupole Mass Detector: Validation and Uncertainty Assessment.

In this work, the uncertainty estimation for the determination of ametryn, carbofuran, atrazine, carbaryl, and methyl parathion in papaya and avocado is presented, along with other validation parameters. The analytical method was developed using Quick, Easy, Cheap, Effective, Rugged, and Safe extraction and ultrahigh performance liquid chromatography coupled to a triple quadrupole mass detector. The method validation showed that the linear correlation coefficients were higher than 0.99 for both fruits. The limits of detection for avocado and papaya were in the range of 0.022 to 0.46 and 0.003 to 0.109 µg/g, respectively. Intermediate precision varied from 5.3% to 13.0% in papaya, and from 4.8% to 20.2% in avocado. Recoveries obtained for each pesticide in both matrices ranged between 61.3% and 119.0%. Matrix effect was calculated for all compounds in both fruits. Finally, the overall uncertainty was lower than 36% for both fruits. PRACTICAL APPLICATION: The present analytical method could be used for pesticides determination in different kind of fruits as papaya and avocado and as a practical guide for uncertainty and matrix effect determination.

Direct immersion single drop micro-extraction method for multi-class pesticides analysis in mango using GC-MS.

Due the negative effects of pesticides on environment and human health, more efficient and environmentally friendly methods are needed. In this sense, a simple, fast, free from memory effects and economical direct-immersion single drop micro-extraction (SDME) method and GC-MS for multi-class pesticides determination in mango samples was developed. Sample pre-treatment using ultrasound-assisted solvent extraction and factors affecting the SDME procedure (extractant solvent, drop volume, stirring rate, ionic strength, time, pH and temperature) were optimized using factorial experimental design. This method presented high sensitive (LOD: 0.14-169.20µgkg-1), acceptable precision (RSD: 0.7-19.1%), satisfactory recovery (69-119%) and high enrichment factors (20-722). Several obtained LOQs are below the MRLs established by the European Commission; therefore, the method could be applied for pesticides determination in routing analysis and custom laboratories. Moreover, this method has shown to be suitable for determination of some of the studied pesticides in lime, melon, papaya, banana, tomato, and lettuce.

Emerging contaminant determination in water samples by liquid chromatography using a monolithic column coupled with a photodiode array detector.

Concern about the presence of emerging contaminants in the environment has increased because biological activity at low concentrations has been observed. The difficulty of detecting and quantifying these compounds encourages the development of analytical methods with highly sensitive and selective analytical procedures. Pharmaceuticals, pesticides, and industrial chemicals are used and finally discarded to the environment. This paper provides a rapid and sensitive analytical method for the quantification of eight emerging contaminants (carbamazepine, carbofuran, bisphenol A, diuron, 17 α ethinylestradiol, ametryn, carbazole, and triclosan). A two-level full factorial design for optimization of chromatographic separation and sample preparation was performed. The separation using a monolithic column (Onyx C18) achieved baseline resolution for all compounds in 4.6 min. The optimized sample treatment involved a preconcentration step by means of solid-phase extraction using HF Bond Elut-C18 cartridges, achieving an enrichment factor of 2222. Under optimum conditions, good linearity was obtained with a correlation coefficient higher than 0.999. The limits of detection and quantification for carbamazepine, carbofuran, bisphenol A, diuron, 17 α ethinylestradiol, ametryn, and carbazole were in the range of 0.01-208.7 and 0.03-695.7 ng L(-1), respectively, and for triclosan, the limit of detection and quantification was 0.67 and 2.25 µg L(-1), respectively. Precision evaluated as relative standard deviations was lower than 15 %. The proposed method was found robust. Finally, the method was successfully applied to superficial water samples.

Analytical method development for the determination of emerging contaminants in water using supercritical-fluid chromatography coupled with diode-array detection.

An analytical method using supercritical-fluid chromatography coupled with diode-array detection for the determination of seven emerging contaminants-two pharmaceuticals (carbamazepine and glyburide), three endocrine disruptors (17α-ethinyl estradiol, bisphenol A, and 17ß-estradiol), one bactericide (triclosan), and one pesticide (diuron)-was developed and validated. These contaminants were chosen because of their frequency of use and their toxic effects on both humans and the environment. The optimized chromatographic separation on a Viridis BEH 2-EP column achieved baseline resolution for all compounds in less than 10 min. This separation was applied to environmental water samples after sample preparation. The optimized sample treatment involved a preconcentration step by means of solid-phase extraction using C18-OH cartridges. The proposed method was validated, finding recoveries higher than 94 % and limits of detection and limits of quantification in the range of 0.10-1.59 µg L(-1) and 0.31-4.83 µg L(-1), respectively. Method validation established the proposed method to be selective, linear, accurate, and precise. Finally, the method was successfully applied to environmental water samples.

Supercritical fluid chromatography with photodiode array detection for pesticide analysis in papaya and avocado samples.

To improve the analysis of pesticides in complex food matrices with economic importance, alternative chromatographic techniques, such as supercritical fluid chromatography, can be used. Supercritical fluid chromatography has barely been applied for pesticide analysis in food matrices. In this paper, an analytical method using supercritical fluid chromatography coupled to a photodiode array detection has been established for the first time for the quantification of pesticides in papaya and avocado. The extraction of methyl parathion, atrazine, ametryn, carbofuran, and carbaryl was performed through the quick, easy, cheap, effective, rugged, and safe methodology. The method was validated using papaya and avocado samples. For papaya, the correlation coefficient values were higher than 0.99; limits of detection and quantification ranged from 130-380 and 220-640 µg/kg, respectively; recovery values ranged from 72.8-94.6%; precision was lower than 3%. For avocado, limit of detection values were ˂450 µg/kg; precision was lower than 11%; recoveries ranged from 50.0-94.2%. Method feasibility was tested for lime, banana, mango, and melon samples. Our results demonstrate that the proposed method is applicable to methyl parathion, atrazine, ametryn, and carbaryl, toxics pesticides used worldwide. The methodology presented in this work could be applicable to other fruits.

Characterisation of tequila according to their major volatile composition using multilayer perceptron neural networks.

Differentiation of silver, gold, aged and extra-aged tequila using 1-propanol, ethyl acetate, 2-methyl-1-propanol, 3-methyl-1-butanol and 2-methyl-1-butanol and furan derivatives like 5-(hydroxymethyl)-2-furaldehyde and 2-furaldehyde has been carried out. The content of 1-propanol, ethyl acetate, 2-methyl-1-propanol, 3-methyl-1-butanol and 2-methyl-1-butanol was determined by means of head space solid phase microextraction gas chromatography mass-spectrometry. 5-(Hydroxymethyl)-2-furaldehyde and 2-furaldehyde were determined by high performance liquid chromatography with diode array detection. Kruskal-Wallis test was used to highlight significant differences between types of tequila. Principal component analysis was applied as visualisation technique. Linear discriminant analysis and multilayer perceptron artificial neural networks were used to construct classification models. The best classification performance was obtained when multilayer perceptron model was applied.

Method development and validation for melamine and its derivatives in rice concentrates by liquid chromatography. Application to animal feed samples.

An isocratic LC method for the determination of melamine and its degradation products (ammelide, ammeline, and cyanuric acid), used to increase the apparent protein content of rice protein concentrate, has been developed. Method development involved optimization of different RP columns, aqueous mobile phases, pH, phosphate concentration, and temperature. The optimum separation of these compounds was achieved using a Luna CN column (30 degrees C), 5 mmol L(-1) sodium phosphate (pH 5.0) as mobile phase, 1 mL min(-1) flow-rate, UV absorbance-DAD detection at 220 nm, and resorcine as internal standard; this enabled separation of these compounds with baseline resolution (values in the 2.1-10.1 range) in about 8 min. Prior to HPLC, the developed sample preparation procedure consisted in a leaching process using the above mentioned mobile phase. Method validation was carried out in rice protein concentrates in accordance with the European Commission decision 2002/657/EC criteria. For this purpose, eight mandatory performance characteristics for the conventional validation approach were determined: calibration graphs, extraction efficiencies, decision limits, detection capabilities, precision (repeatability and within-laboratory reproducibility), accuracy, selectivity, and robustness. The extraction efficiencies for these compounds were in the range 99-100% and the within-laboratory reproducibility at 1.0, 1.5, and 2.0 detection capabilities concentration levels were smaller than 5, 4, and 3%, respectively. Finally, the proposed method was successfully applied to the analysis of other rice protein concentrates and several animal feed samples.

Sample preparation for the determination of steroids (corticoids and anabolics) in feed using LC.

An improved sample preparation procedure for the determination of 17 steroids (corticoids (CC) and androgenic anabolic steroids (AAS)), used potentially as growth promoters, in feed samples has been developed. This procedure is based on two reported LC-UV methods. The improved procedure includes a leaching process using ACN, saponification, and SPE using polymeric cartridges. The proposed method was validated according to the EU criteria established for quantitative screening methods in PFS. The extraction efficiencies, decision limits (CCalpha) and detection capabilities (CCbeta), for these compounds were in the ranges of 82-100%, 19-40, and 24-53 microg/kg, respectively. The repeatability and the within-laboratory reproducibility at 1.0, 1.5, and 2.0 CCbeta levels were smaller than 10%. Accuracy was in the 97-101% range. The robustness was evaluated using the Youden robustness test. This method was applied to the analysis of steroids in different kinds of FS with satisfactory results.

GC-MS method development and validation for anabolic steroids in feed samples.

A GC-MS method for the determination of AAS used as growth promoting agents using SIM in piglet feed samples has been developed and validated, using testosterone as internal standard. The formation of volatile steroid derivatives was carried out by derivatization with N-methyl-N-(trimethylsilyl)trifluoroacetamide. The optimum separation was achieved using a Zebron ZB-5 column under a gradient temperature elution, allowing the separation of steroids in 18 min. The required sample treatment process was discussed. A leaching using ACN, saponification using a binary NaOH/MgCl2 solution, and LLE using ethyl acetate were finally selected. Method validation has been carried out according to the Commission Decision 2002/657/EC criteria established for quantitative confirmatory methods. The extraction efficiencies, CCalpha and CCbeta for these compounds were in the ranges 78-98%, 10-21 and 18-35 mug/kg, respectively. The repeatability and the within-laboratory reproducibility at 1, 1.5, and 2 CCbeta concentration levels were smaller than 8.2, 7.5, and 5.8% and 12.2, 9.5, and 7.5%, respectively. Accuracy was in the 99-103% range. The robustness was evaluated using the Youden robustness test. The proposed method was applied to the analysis of steroids spiked in different kinds of animal feed samples with satisfactory results.