Dispersive liquid-liquid microextraction (DLLME) for determination of tricyclic antidepressants in whole blood and plasma samples and analysis by liquid chromatography with diode array detector (LC-DAD).

Microextractions have been developed for the tricyclic antidepressants (TCAs) analysis in biological matrices, including dispersive liquid-liquid microextraction (DLLME). The proposed DLLME employed 490 µL of biological sample (whole blood or plasma), which were added 15 mg of NaCl, 10 µL of medazepam as internal standard (10 µg/mL) and 100 µL of 2 M NaOH. This mixture was homogenized by vortex (2800 rpm/10 s) and 400 µL of hexane (extractor solvent) with 600 µL of methanol (dispersing solvent) were added to the sample. After the vortex step (2800 rpm/5 s), an ultrasonic bath for 300 s was employed. Then, this content was centrifuged (10 min/10000 rpm), organic phase was collected and dried under air flow. After, 30 µL of the mobile phase was used for resuspension and 20 µL is injected into LC-DAD. This method was optimized and fully validated according to UNODC and SWGTOX guidelines, reaching limits of detection equivalent to analytical methodologies that employ mass spectrometry (MS). Also, it was applied in real cases involving suspected exposure to TCAs. So, the developed DLLME for the determination of TCAs in whole blood and plasma samples proved to be a simple, reliable, robust and reproducible method that can be used in toxicology and clinical laboratories.

The association of modified QuEChERS and DLLME to offer high analytical detectability to assess residual depletion profile of erythromycin in fish.

An analytical method for the determination of erythromycin A (ERY) residues in fish fillet was developed, optimized, and validated employing a modified QuEChERS procedure associated to DLLME technique as a preconcentration step. The obtained LOD and the LOQ were 0.1 µg kg-1 and 1 µg kg-1, respectively. The validated method provides linearity in the range of 1 to 20 µg kg-1, precision (CV < 6.3 %) and accuracy (recovery ranging from 103 to 110 %). The procedure was applied in an experimental study to evaluate the residual depletion profile of ERY in fish (Piaractus mesopotamicus) after oral administration. The treatment was carried out at a daily dose of 100 mg (kg BW)-1 of ERY, for 7 consecutive days and with an average water temperature of 30 °C. A withdrawal time of 240°-day was estimated for eliminating ERY residues at concentration levels below the maximum residue limit considered (MRL 100 µg kg-1).

Multivariate optimization of a dispersive liquid-liquid microextraction method for determination of copper and manganese in coconut water by FAAS.

In this study, multivariate methodologies were applied in the optimization of a dispersive liquid-liquid microextraction (DLLME) method, aiming at the determination of Cu and Mn in coconut water samples by flame atomic absorption spectrometry. Some extractors (chloroform and CCl4), dispersants (ethanol, methanol and acetonitrile) and complexing agents (5-Br-PADAP and Dithzone) were previously tested in the extraction. A mixture design was used to optimize the component proportions formed by chloroform (10%), acetonitrile (76%), and 0.020% 5-Br-PADAP solution (14%). Doehlert design optimized the variables pH, NaCl, and buffer amounts for the extraction of both metals. The following analytical characteristics, respectively for Cu and Mn, were accessed: limit of quantification (4.83 and 3.32 µg L-1), enrichment factors (11 and 8 fold), and precision (6.6 and 6.0% RSD, n = 10). Addition/recovery tests of the analytes allowed to find values in the range of 96.5-120% for Cu and 99-107% for Mn.

Development of a novel UHPLC-MS/MS method for the determination of ochratoxin A in tea.

The mycotoxin Ochratoxin A (OTA) is responsible for producing many effects on human and animal health. In this work, the evaluation of the presence of OTA in tea beverage samples consisted of extraction and preconcentration through the solidification of a floating organic drop (DLLME-SFO) combined with an additional octadecyl silane clean-up step. The obtained extract was analyzed by UHPLC-MS/MS. Interferences from the matrix were effectively reduced and, consequently, recovery increased from 43.18% ± 4.1%-96.02% ± 2.54%. The validation assays were carried out by external calibration and spiked samples, with satisfactory recoveries. An adequate dynamic calibration range was obtained over a concentration interval between 0.5 and 70 µg mL-1 OTA. Capabilities of detection and quantification were 0.5 and 1.4 µg mL-1. The obtained Green Certificate was compared with other techniques to establish the greenness profile of the procedure. Quantification of ochratoxin A levels in tea samples was performed.

Phthalic acid esters and adipates in herbal-based soft drinks: an eco-friendly method.

Phthalic acid esters (PAEs) and adipates are plasticizers with high applicability in several products and building materials (e.g. cosmetics, packing) very persistent in the environment, features which render them ubiquitous pollutants. These substances can contaminate food through the environment (water, air, and soil) and/or migration from packaging materials, which creates a health concern due to their toxicity. This paper describes an eco-friendly dispersive liquid-liquid microextraction (DLLME) procedure to extract five phthalates and bis(2-ethylhexyl) adipate (DEHA) from bottled herbal-based beverages followed by GC-MS/MS quantification. The method showed low limits of detection (5.0-13 µg L-1) and quantification (20-35 µg L-1), good inter- and intraday precision (RSD < 19%), and recoveries ranging from 82 to 111%. It was applied to 16 real samples, of which 13 showed the presence of at least one of the analytes under study. Additionally, an exposure assessment was performed, and resulted in a hazard quotient less than 1 (HQ < 1) for all analytes. Therefore, PAEs and DEHA found in samples do not pose a health issue.

Quantification of amphetamine and derivatives in oral fluid by dispersive liquid-liquid microextraction and liquid chromatography-tandem mass spectrometry.

The abuse of stimulants such as amphetamine, methamphetamine, ecstasy (MDMA), and their analogues (MDEA and MDA) has been increasing considerably worldwide since 2009. In this work, an analytical method using dispersive liquid-liquid microextraction (DLLME) to determine amphetamine and derivatives in oral fluid samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and validated. Linearity was achieved between 20 to 5000 ng/mL (r>0.992, 1/x² weighted linear regression), with a limit of quantification (LOQ) of 20 ng/mL. Imprecision (%relative standard deviation) and bias (%) were not higher than 9.1 and -12.3%, respectively. The matrix effect was lower than 14.6%, with no carryover observed up to 5000 ng/mL and no interference with 10 different oral fluid matrix sources and against 14 pharmaceuticals and other common drugs of abuse. MDMA, MDA, and MDEA in processed samples were stable up to 24 h at autosampler (10°C); and amphetamine and methamphetamine up to 18 h. The developed method was successfully applied to authentic oral fluid analyses (n = 140). The proposed method is an example of the Green Analytical Toxicology, since it reduces both the amount of solvent required in samples preparation and the quantity of solvents and reagents used in analytical-instrumental stage, as well as requires a minimal sample volume, being a cheaper, quicker and more ecological alternative to conventional methods. Obtained results showed that DLLME extraction combined with LC-MS/MS is a fast and simple method to quantify amphetamine derivatives in oral fluid samples.

Multi-phytochemical determination of polar and non-polar garlic bioactive compounds in different food and nutraceutical preparations.

Amongst functional foods, garlic and its by-products stand out given their rich phytochemical profile. A comprehensive analytical approach becomes necessary to fully address garlic preparations health-promoting activities, considering the coexistence of several active ingredients from different chemical families. For this, we developed a multi-phytochemical protocol combining Ultrasound and Dispersive Liquid-Liquid Microextraction, coupled to Liquid Chromatography, for the determination of flavonols, organosulfur compounds, and inulin. Hydrophilic interaction chromatography showed an adequate resolution of flavonols and sugars in a shorter time. The protocol showed a suitable performance and acceptable quantitative yields for garlic powder, cooked garlic, black garlic, and liquid garlic flavouring samples. Additionally, the proposed methodology represented a useful tool to assess how the different garlic products related to functional properties, taking into account the various phytochemical families present in each sample. This is the first time a comprehensive and multi-phytochemical validated analysis of garlic preparations is proposed.

DLLME-SFO-GC-MS procedure for the determination of 10 organochlorine pesticides in water and remediation using magnetite nanoparticles.

There exists a high demand for fast, simple, and reliable methodologies for determining the presence of organochlorine pesticides (OCPs) on environmental samples. Moreover, the toxicity and accumulation of potential OCPs in several environments have led to the development of technologies that achieve their removal from contaminated waters. In this study, a novel method combining a dispersive liquid-liquid microextraction procedure based on the solidification of floating organic drop is developed and validated for the extraction, preconcentration, and determination of 10 OCPs: α-BHC, p,p'-DDE, δ-BHC, dieldrin, p,p'-DDT, endosulfan I, endosulfan sulfate, heptachlor, heptachlor epoxide (isomer B), and methoxychlor in water samples. The results show that the calibration curves were linear for all the studied compounds, and the coefficients of correlation higher than 0.99. The variation coefficient for precision and accuracy was lower than 10%, and the accuracy ranged from 93 to 105%. Low limit of detection and limit of quantification values ranging from 0.06-3.00 ng mL-1 and 0.20-10 ng mL-1 were obtained, respectively. The capability of the proposed method was confirmed using an analysis of the water samples before and after the degradation process; this was achieved by employing nanomaterials, while performing an analysis of 160 real samples that were sourced from a Brazilian river. A cobalt-doped magnetite was applied for the environmental remediation of the studied compounds, and it was verified that the novel material has the potential to be used in environmental remediation with a degradation efficiency exceeding 80% for the majority of the studied compounds.

A simple, rapid and low cost reversed-phase dispersive liquid-liquid microextraction for the determination of Na, K, Ca and Mg in biodiesel.

In this work a method based on reversed-phase dispersive liquid-liquid microextraction (RP-DLLME) as sample preparation for the extraction and preconcentration of Na, K, Ca and Mg in biodiesel samples was developed. The analytes determination was performed by flame atomic absorption spectrometry (FAAS), operating in emission mode for Na and K and in absorption mode for Ca and Mg. The extraction/preconcentration step of the analytes was performed by using a mixture of dispersant and extractant solvents (isopropanol and HNO3, respectively) and the aqueous phase containing the analytes was separated by centrifugation. Some parameters such as sample mass, type and volume of dispersant and extractant solutions, HNO3 concentration (extraction solution), use of ultrasound, centrifugation time and temperature were evaluated. During the optimization of RP-DLLME, biodiesel samples were spiked with a multi-element biodiesel B100 (Conostan®) with final concentration of 1.0 µg g-1 of the analytes. Analytes determination was performed by FAAS using external calibration with aqueous reference solutions. The limits of quantification (LOQ) for Na, K, Ca and Mg were 0.04; 0.02; 0.05 and 0.08 µg kg respectively. The accuracy was evaluated by recovery tests, which ranged from 93.9% to 108.1%, with relative standard deviation lower than 3% for all analytes. Then, the proposed method was applied for analytes determination in five biodiesel samples produced from different raw materials. Comparing to conventional methods for elements determination in biodiesel (e.g., dilution with organic solvent, sample digestion, etc.), RP-DLLME combined to FAAS is simple, low cost, low reagents consumption and provides LOQs values significantly below compared to the limits established in the legislation for these elements in biodiesel.

Occurrence of cocaine and metabolites in hospital effluent - A risk evaluation and development of a HPLC method using DLLME.

A fast method for the determination of cocaine and its metabolites in hospital effluent samples was worked out by using liquid chromatography with the aid of fluorescence and diode array detection. Solid phase extraction and dispersive liquid -liquid microextraction were employed during the sample preparation stage. The experiment was conducted by using Chromabond® C18 ec 6 ml/500 mg cartridges, with recoveries higher than 96.6%, 88.3%, 78.7%, and LOQm 0.15; 0.18 and 0.30 µg L-1 for cocaine, benzoylecgonine and anhydroecgonine respectively. In the case of DLLME, different chemical conditions and solvent combinations were tested to find the best settings for the microextraction: pH 9; addition of 0.3 mol L-1 NaCl; 150 µL extractor (chloroform) and 350 µL disperser (methanol). The recoveries for cocaine were as high as 98.3% with LOQm 0.3 µg L-1. After validation, these methods were applied to quantification of the analytes. While the concentration of the anhydroecgonine, (the main pyrolytic metabolite of cocaine), remained below the limit of detection, the range of concentrations of cocaine and benzoylecgonine determined were 0.4-4.9 µg L-1 and 0.9-8.6 µg L-1, respectively. The occurrence has a relatively median/high environmental impact. These concentration values suggest that a role is played by other sources of cocaine, probably related to transport, or handling and the consumption of the drug. The outcome is that cocaine can be quantified by using DLLME as well as SPE, however, DLLME offered clear benefits like simplicity, affordability, and speed, as well as only requiring a small volume of solvents and samples.

Development of garlic bioactive compounds analytical methodology based on liquid phase microextraction using response surface design. Implications for dual analysis: Cooked and biological fluids samples.

Organosulphur compounds (OSCs) present in garlic (Allium sativum L.) are responsible of several biological properties. Functional foods researches indicate the importance of quantifying these compounds in food matrices and biological fluids. For this purpose, this paper introduces a novel methodology based on dispersive liquid-liquid microextraction (DLLME) coupled to high performance liquid chromatography with ultraviolet detector (HPLC-UV) for the extraction and determination of organosulphur compounds in different matrices. The target analytes were allicin, (E)- and (Z)-ajoene, 2-vinyl-4H-1,2-dithiin (2-VD), diallyl sulphide (DAS) and diallyl disulphide (DADS). The microextraction technique was optimized using an experimental design, and the analytical performance was evaluated under optimum conditions. The desirability function presented an optimal value for 600µL of chloroform as extraction solvent using acetonitrile as dispersant. The method proved to be reliable, precise and accurate. It was successfully applied to determine OSCs in cooked garlic samples as well as blood plasma and digestive fluids.

Multiclass pesticide analysis in fruit-based baby food: A comparative study of sample preparation techniques previous to gas chromatography-mass spectrometry.

With the aim to develop a new gas chromatography-mass spectrometry method to analyze 24 pesticide residues in baby foods at the level imposed by established regulation two simple, rapid and environmental-friendly sample preparation techniques based on QuEChERS (quick, easy, cheap, effective, robust and safe) were compared - QuEChERS with dispersive liquid-liquid microextraction (DLLME) and QuEChERS with dispersive solid-phase extraction (d-SPE). Both sample preparation techniques achieved suitable performance criteria, including selectivity, linearity, acceptable recovery (70-120%) and precision (⩽20%). A higher enrichment factor was observed for DLLME and consequently better limits of detection and quantification were obtained. Nevertheless, d-SPE provided a more effective removal of matrix co-extractives from extracts than DLLME, which contributed to lower matrix effects. Twenty-two commercial fruit-based baby food samples were analyzed by the developed method, being procymidone detected in one sample at a level above the legal limit established by EU.

Ultrasound-assisted dispersive liquid-liquid microextraction of tetracycline drugs from egg supplements before flow injection analysis coupled to a liquid waveguide capillary cell.

A simple, rapid, and efficient ultrasound-assisted dispersive liquid-liquid microextraction (US-DLLME) method was developed for extraction of tetracycline residues from egg supplement samples, with subsequent determination by flow injection analysis (FIA) coupled to a liquid waveguide capillary cell (LWCC) and a controlled temperature heating bath. Tetracyclines react with diazotized p-sulfanilic acid, in a slightly alkaline medium, to form azo compounds that can be measured at 435 nm. The reaction sensitivity improved substantially (5.12-fold) using an in-line heating temperature of 45 °C. Multivariate methodology was used to optimize the factors affecting the extraction efficiency, considering the volumes of extraction and disperser solvents, sonication time, extraction time, and centrifugation time. Good linearity in the range 30-600 µg L(-1) was obtained for all the tetracyclines, with regression coefficients (r) higher than 0.9974. The limits of detection ranged from 6.4 to 11.1 µg L(-1), and the recoveries were in the range 85.7-96.4 %, with relative standard deviation lower than 9.8 %. Analyte recovery was improved by approximately 6 % when the microextraction was assisted by ultrasound. The results obtained with the proposed US-DLLME-FIA method were confirmed by a reference HPLC method and showed that the egg supplement samples analyzed were suitable for human consumption.