Low Temperature Partitioning Research Articles

Liquid-liquid and solid-liquid extractions with low-temperature partitioning – A review

The paper represents the first review of solvent extraction techniques utilizing the low-temperature partitioning/purification (LTP) approach. Initially conceived in the 1960s to purify extracts from fatty matrices, it wasn't until the 2000s that this approach received increasing attention for its efficacy in extracting organic compounds from diverse samples, often without additional cleanup steps. This review covers a brief history and proposes a mechanism for LTP-based solvent extraction. Furthermore, the principal practical issues of the technique are spotlighted, elucidating the factors influencing extraction efficiency. The advantages, limitations, and potential combinations with other extraction techniques of the LTP-based solvent extractions are analyzed. The versatility of the LTP approach is demonstrated by its applications in extracting various compounds from food, environmental, and biological samples, emphasizing its potential for rapid sample preparation with minimal steps, few chemicals, and minimal analyst intervention.

Determination of pesticide residues in oat flour using low-temperature partition extraction and GC-MS analysis.

The online version contains supplementary material available at 10.1007/s13197-024-06006-z.

A faster and more accessible method for the analysis of acephate and methamidophos in water samples by LC-MS/MS

ABSTRACT Pesticide pollution on environmental matrices has attracted increasing attention worldwide. Pesticide runoff from agricultural crops into surface waters may impact ecosystems and human health through drinking water consumption in pesticide-polluted areas. This study aims to develop and validate a simpler, faster, and more accessible methodology for the analysis of organophosphate pesticides, such as acephate and methamidophos, using HPLC-ESI-MS (QqQ). Acephate and methamidophos are two of the most common and efficient systemic pesticides in the organophosphate family, known for their high effectiveness against insects and pests. Firstly, different extractions were tested: liquid-liquid extraction (LLE), low-temperature partitioning extraction (LTPE) and solid-phase extraction (SPE) with a usual and accessible cartridge, C18. LLE and LTPE showed low sensitivities, probably because acephate and methamidophos are extremely hydrophilic compounds, like many organophosphorus pesticides. Thus, they have low interaction with the extractor solvent, resulting in low extraction rates. SPE with C18 cartridge led to the best extraction of acephate and methamidophos in water matrices and was chosen for the validated process. The selected method ensured acceptable recoveries, within the same range found in the scientific literature (9–49%) and within relative standard deviations below 20%. However, future efforts regarding other types of cartridges are encouraged. The limit of detection (LOD) and limit of quantification (LOQ) of the analytical method were 0.2 µg/L and 0.5 µg/L for acephate and methamidophos, values lower than those reported in the scientific literature. The developed method was used to quantify the levels of such organophosphate pesticides in samples from Brazilian surface water and none of the target pesticides were detected in these aquatic matrices.

Eco-friendly alternatives for propoxur extraction from meat

Propoxur, an insecticide used to control opportunistic fleas and flies, is mainly ingested with meat. Considering that the common methods of propoxur determination in meat are time-consuming, employ toxic extraction solvents, and generate large amounts of waste, we herein established greener, faster, and cheaper alternatives. Two methods were developed: flow solid-liquid extraction or solid-liquid microextraction with low-temperature partitioning. Increasing the sensitivity and decreasing the limit of detection were accomplished by employing cloud point preconcentration of the intensely colored reaction product and long pathlength spectrophotometry. The method shows a linear response range within 0.01–1.0 µmol L−1 and coefficient of variation = 5.0%, n = 15. The limits of detection and quantification were estimated at 7.9 and 26.2 µg kg−1 at the 99.7% confidence level, respectively. The parameters were lower than the maximum residue limit of propoxur in meat (50.0 μg kg−1), and the recoveries were obtained for spiked meat samples (75–112%). The proposed methods for propoxur extraction are practical, easy to implement, and simple to perform, in addition to requiring low amounts of solvents and low waste generation.

Development of methods based on low-temperature partitioning (LTP) for monitoring cresols and chlorophenols in sewage sludge, soil, and water in column leaching

Cresols and chlorophenols are chemical contaminants that are potentially toxic to humans and can be found in sewage sludge. These chemical contaminants can migrate into the sludge-soil-water system when sludge is used as a conditioner for agricultural soils. Thus, the objective of this study was to develop methodologies based on extraction with low-temperature partitioning (LTP) to determine cresols and chlorophenols in sewage sludge, soil, and water. The analysis was performed by gas chromatography coupled with mass spectrometry (GC-MS). The validated methods were applied to monitor cresols and chlorophenols in a column-leaching study of a sludge-soil-water system. Satisfactory results were achieved for selectivity, limit of quantification (LOQ), linearity, accuracy, and precision. In the column leaching study, only 2,4,6-trichlorophenol was quantified in sludge samples after 20 days of the experiment. None of the studied compounds were quantified in soil and leached water samples, due to the degradation promoted by the microorganisms present in the sewage sludge. Finally, validated methods were suitable for monitoring cresols and chlorophenols in the sludge-soil-water system.

Unique microstructure formations during low-temperature partitioning after intercritical annealing in low alloy multi-phase TRIP steel and their mechanical behavior clarified by in-situ synchrotron X-Ray diffraction

Strong attentions have been paid to low-carbon multi-phased steels showing transformation induced plasticity (TRIP) effect as good candidates for automotive applications due to their good mechanical balance between strength and ductility. However, details of complicated microstructural evolutions during thermo-mechanical processing and the roles of constituent phases on mechanical properties have not yet been fully clarified. In the present study, the formation process of multi-phased microstructures in a low alloy steel (Fe-0.2C-1.6Mn-1.4Si-1.0Ni-0.5Al: wt.%) during intercritical annealing in austenite + ferrite temperature (830 °C) and subsequent partitioning heat-treatment at lower temperature (400 °C) were systematically investigated. The phase fraction of ferrite (F), martensite (M), and retained austenite (A) significantly changed with increasing the holding time at 400 °C. It was observed that austenite transformed into ferrite during the heat-treatment at 400 °C to form newly formed ferrite having different characteristics. The ferrite in the final microstructures was categorized into four types (Type I, II, III and IV), based on their morphologies and other features. The ferrite newly formed at 400 °C (Type II, III, IV) were concluded to be formed by massive or bainitic transformation from their characteristics, i.e., morphologies, existence of surface relief, dislocations and misorientations, chemical compositions, and thermodynamic considerations. Long-range diffusion of substitutional elements did not occur in the phase transformation, but interstitial carbon diffused and enriched into austenite, resulting in large fractions of retained austenite at room temperature. Tensile mechanical properties of the obtained multi-phase steel were systematically clarified by in-situ synchrotron X-Ray diffraction. Tensile elongation increases with increasing the holding time at 400 °C, because the amount of retained austenite increased with the partitioning heat-treatment and they showed the TRIP effect through deformation-induced martensitic transformation during tensile deformation. On the other hand, the best strength-ductility balance was obtained in the specimen experienced the shortest heat-treatment at 400 °C.

Evaluation of imazalil dissipation/migration in postharvest papaya using low-temperature partition extraction and GC–MS analysis

Methods involving solid-liquid extraction with low-temperature partition and analysis by gas chromatography coupled to mass spectrometry (GC–MS) were validated to investigate the dissipation/migration of residues of the postharvest fungicide imazalil in papaya skin, pulp, and seeds. The fruits were stored for 23 days (14 °C). Every two days, fruits from the control group and those treated with imazalil had their skin, outer pulp, inner pulp, and seeds separated and then analyzed by GC–MS. After the 23rd day, about 70% of the imazalil had dissipated. Most of the remaining residue was found in the skin; however, the small amount migrating into the pulp was above the maximum residue levels allowed by the regulatory agencies. Imazalil residue was also detected in seeds at concentrations lower than the LOQ (0.025 mg kg−1). Mass loss was the only quality parameter that showed a significant difference between the fruits of the control and study groups.

Strong and ductile medium manganese steel processed by low-temperature partitioning

Conventional medium Mn steels processed by intercritical annealing (IA) demonstrate low yield strength. The present work investigates the effect of low-temperature partitioning (LTP) on the microstructure and tensile properties of medium Mn steel. It is found that medium Mn steel processed by LTP at 300°C possesses ultra-high yield strength of 1683 MPa and proper uniform elongation of 11.3%. The LTP process does not reduce the yield strength but substantially enhances the tensile ductility. The increase of the tensile ductility after LTP treatment can be ascribed to the reduction of the residual stress, martensitic transformation, and the well-developed ductile fracture behaviour. The present LTP process provides an alternative pathway to develop strong and ductile medium Mn steel.

Low-Temperature Partitioning: A Simple Screening Method for Determining Diethylene Glycol in Beer by Gas Chromatography

Diethylene glycol is an extremely toxic substance to humans. Recently, cases of beer contamination in Brazil have raised awareness of the need for developing simple screening methods to evaluate this type of compound. This research developed a liquid-liquid extraction with low-temperature partitioning technique to determine diethylene glycol in beer via gas chromatography. Employing a flame-ionization detector simplifies the method, lowers its cost and therefore, it can be used as screening step to assess the possibility of contamination. A gas chromatograph coupled to a mass spectrometer would be used only for a confirmatory analysis. The optimized method was validated for the main figures of merit, and it proved to be adequate, with good values of recovery rate (94-106%), limit of detection (3.0 mg L-1), and quantification (10.0 mg L-1). Accuracy, in terms of repeatability and intermediate accuracy, showed variation coefficients lower than or equal to 20%. This method was applied to 28 samples of beers marketed in Brazil, and diethylene glycol was found above the limit of detection in three of them (10.7%). These results were confirmed by a gas chromatograph coupled to a mass spectrometer, which showed the reliability of the screening method for determining diethylene glycol in beer samples.

A feasible route to produce 1.1 GPa ferritic-based low-Mn lightweight steels with ductility of 47%

High- and medium-Mn (H/M-Mn) base lightweight steels are a class of ultrastrong structural materials with high ductility compared to their low-Mn counterparts with low strength and poor ductility. However, producing these H/M-Mn materials requires the advanced or high-tech manufacturing techniques, which can unavoidably provoke labor and cost concerns. Herein, we have developed a facile strategy that circumvents the strength–ductility trade-off in low-Mn ferritic lightweight steels, by employing low-temperature tempering-induced partitioning (LTP). This LTP treatment affords a typical Fe-2.8Mn-5.7Al-0.3C (wt.%) steel with a heterogeneous size-distribution of metastable austenite embedded in a ferrite matrix for partitioning more carbon into smaller austenite grains than into the larger austenite ones. This size-dependent partitioning results in slip plane spacing modification and lattice strain, which act through dislocation engineering. We ascribe the simultaneous improvement in strength and total elongation to both the size-dependent dislocation movement in austenite grains and the controlled deformation-induced martensitic transformation. The low-carbon-partitioned large austenite grains increase the strength and ductility as a consequence of the combined martensitic transformation and high dislocation density-induced hardening and by interface strengthening. Additionally, high-carbon-partitioned small austenite grains enhance the strength and ductility by planar dislocation glide (in the low strain regime) and by cross-slipping and delayed martensitic transformation (in the high strain regime). The concept of size-dependent dislocation engineering may provide different pathways for developing a wide range of heterogeneous-structured low-Mn lightweight steels, suggesting that LTP may be desirable for broad industrial applications at an economic cost.

Development and validation of a solid–liquid extraction with low-temperature partitioning method for the determination of fipronil in turtle eggshell

The intense use of fipronil in sugarcane crops in Brazil in regions close to the spawning areas of freshwater turtles may pose a considerable threat to the reproduction of these organisms. Therefore, the development and validation of a method to quantify the fipronil contamination in turtle eggshells is pressing and constitutes the main goal of the present study. The proposed method was based on solid–liquid extraction with low-temperature partitioning, reducing its scale due to the limited availability of turtle eggshell samples. The fipronil extraction from eggshell samples was optimized using a statistical design based on the Doehlert Matrix. Eggshell mass, the volume of extraction solvent, and the freezing time were the optimized method parameters, yielding fipronil recoveries close to 100% without a clean-up step. Furthermore, the optimized method was linear, robust, precise, and accurate in the fipronil concentration range of 8.4–1,818.0 µg kg−1. The limit of quantification for fipronil was 8.37 µg kg−1, about 2.5 times lower than the maximum residual limit for fipronil in eggs. Residues of fipronil were detected and quantified successfully in amazon-turtle eggshell samples using the proposed method. In conclusion, the one-step SLE-LTP method was mini-scaled for the first time and presented a strong potential for monitoring fipronil residues in freshwater turtle eggshells.

Microextraction technique associated with gas chromatography–mass spectrometry for determining pesticide residues in urine

Urine is one of the biological matrices most used for detecting human contamination, as it is representative and easily obtained via noninvasive sampling. This study proposes a fast, accurate, and ecological method based on liquid–liquid microextraction with low-temperature partition (μLLE/LTP). It was validated to determine nine pesticides (lindane, alachlor, aldrin, chlorpyrifos, dieldrin, endrin, DDT, bifenthrin, and permethrin) in human urine, in association with gas chromatography coupled with mass spectrometry (GC–MS). The technique was optimized through a factorial design. The best conditions for the simultaneous extraction of the analytes comprised the addition of 600 µL of water and 600 µL of acetonitrile (extracting solvent) to a 500-µL urine sample, followed by vortexing for 60 s. By freezing the samples for 4 h, it was possible to extract the pesticides and perform the extract clean-up simultaneously. The parameters selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, and accuracy were used to appraise the performance of the method. Good values of selectivity and linearity (R 2 > 0.990), LOQ (0.39–1.02 μg L−1), accuracy (88–119% recovery), and precision (%CV ≤ 15%) were obtained. The μLLE/LTP–GC–MS method was applied to authentic urine samples collected from volunteers in Southeast Brazil.

Determination of Pesticides in Soybean Seeds Incorrectly Discarded Near a Spring of the Paranaíba River, GO-Brazil.

The objective of this research was to evaluate the contamination of pesticides of carbamate and benzimidazole classes in soil, water and soybean seeds, incorrectly discarded near a spring in the state of Goiás-Brazil. The Solid-Liquid and Liquid-Liquid Extraction with Low Temperature Partition (SLE/LTP or LLE/LTP) methods were used for pesticide extraction and the analyses were performed by HPLC-UV. A high resolution mass spectrometer was used to confirm the identity of the compounds present in the seeds. The results showed that the soybeans were treated with the pesticide carbendazim and the dosage was three times higher than established by Brazilian legislation. In the soil and water analyzed there was no presence of the pesticides researched, nor of the carbendazim detected in the seeds. Since this was an environmental crime due to incorrect disposal, it is not known how long ago it occurred. Thus, depending on how long the seeds had been exposed there, the pesticide could have leached out, and caused contamination in the spring and soil. Thus, we conclude that the incorrect disposal of seeds treated with pesticides can be a risk to the permanence of life on the site.

Development of 1.2 GPa Ferrite-based Lightweight Steels via Low-temperature Tempering

Previously reported low-Mn ferritic-based lightweight steels are potential candidates for industrial applications, however, they typically exhibit lower strength, with < 1 GPa and lower strength-ductility balance, than medium- and high-Mn austenitic lightweight steels. Herein, we introduce a low-temperature tempering-induced partitioning (LTP) treatment that avoids the strength-ductility dilemma of low-Mn ferriticbased steels. When the LTP process was performed at 330 oC for 665 s, the strength of typical ferritic base Fe-2.8Mn5.7Al0.3C (wt%) steel with heterogeneously sized metastable austenite grains embedded in a ferrite matrix, exceeded 1.1 GPa. Notably, the increased strength-ductility balance of the LTP-processed ferritic steel was comparable to that of the high-Mn based austenitic lightweight steel series. Using microscale to nearatomic scale characterization we found that the simultaneous improvement in strength and total elongation could be attributed to size-dependent dislocation movement, and controlled deformation-induced martensitic transformation.

Development of 1.2 GPa Ferrite-based Lightweight Steels via Low-temperature Tempering

Previously reported low-Mn ferritic-based lightweight steels are potential candidates for industrial applications, however, they typically exhibit lower strength, with < 1 GPa and lower strength-ductility balance, than medium- and high-Mn austenitic lightweight steels. Herein, we introduce a low-temperature tempering-induced partitioning (LTP) treatment that avoids the strength-ductility dilemma of low-Mn ferriticbased steels. When the LTP process was performed at 330 oC for 665 s, the strength of typical ferritic base Fe-2.8Mn5.7Al0.3C (wt%) steel with heterogeneously sized metastable austenite grains embedded in a ferrite matrix, exceeded 1.1 GPa. Notably, the increased strength-ductility balance of the LTP-processed ferritic steel was comparable to that of the high-Mn based austenitic lightweight steel series. Using microscale to nearatomic scale characterization we found that the simultaneous improvement in strength and total elongation could be attributed to size-dependent dislocation movement, and controlled deformation-induced martensitic transformation.

The efficacy of washing strategies in the elimination of fungicide residues and the alterations on the quality of bell peppers

Food safety problems caused by pesticide residues in vegetables have become a top issue to raise public concern. In this study, bell peppers were grown in an experimental field and sprayed with two systemic (azoxystrobin and difenoconazole) and one contact (chlorothalonil) fungicides. Ozone (ozonated water and water continuously bubble with ozone) or conventional domestic (washing with distilled water, detergent, acetic acid, sodium bicarbonate, and sodium hypochlorite solutions) procedures were investigated to identify the most effective way to remove fungicide residues in bell peppers. The residues in the fruits and the washing solutions were determined by solid–liquid extraction with a low-temperature partition (SLE/LTP) and liquid–liquid extraction with a low-temperature partition (LLE/LTP), respectively, and analyzed by gas chromatography. Water continuously bubbled with ozone a concentration of 3 mg L-1 was the most efficient treatment with removal of fungicides residues ranging from 67% to 87%. However, similar treatment at a lower concentration (1 mg L-1) did not only efficiently removed fungicide residues (between 53% and 75%) but also preserving the quality of the fruit along a storage time of 13 days. Among the conventional solutions, sodium bicarbonate at 5% showed good efficiency removing between 60% and 81% of the fungicide residues from bell peppers, affecting the color quality of the fruit. Overall, the most affected physicochemical parameters in bell peppers after the treatments were weight loss, color, and vitamin C content.

Low-temperature partitioning extraction followed by liquid chromatography tandem mass spectrometry determination of multiclass antibiotics in solid and soluble wastewater fractions

An analytical method based on low-temperature partitioning extraction (LTPE) followed by high performance liquid chromatography coupled to triple quadrupole mass spectrometry analysis was developed and validated for the determination of eight multiclass antibiotics in wastewater. The analyzed target antibiotics included one β-lactam, two sulfonamides, three fluoroquinolones, one macrolide and one diaminopyrimidine. LTPE parameters such as sample pH, volume ratio between sample and extractor solvent, ultra-sonic extraction time, extraction tube material, solvent and volume to reconstitute the sample extracts, were optimized. Additionally, the influence of solids on extraction efficiency was evaluated. Quantification of the target antibiotics was performed by double consecutive injection method, without the use of a labeled compound, in order to correct matrix effects. The whole samples were analyzed, including, liquid and solid fractions of wastewater. The results revealed that the filtration step can underestimate the total antibiotics concentration, particularly to the hydrophobic compounds that have higher affinity for solids, indicating that the suspended wastewater particulate should not be neglected. The method detection limit ranged from 18.54 ng L−1 (trimethoprim) to 78.49 ng L−1 (ciprofloxacin). Intra-day precision of less than 12.3% was achieved. The recoveries values ranged from 13.9% (sulfadiazine) to 48.9% (erythromycin) in influent samples and from 19.1% (sulfadiazine) to 57.2% (ciprofloxacin) in effluent samples. The method was applied to the measurement of antibiotic residues in influent and effluent from wastewater treatment plants. The majority target antibiotics were detected in wastewater samples. Their concentrations ranged from 237 to 9553 ng L−1 in influent and from 212 to 1660 ng L−1 in effluent. This work provides new insights on the applicability of LTPE for antibiotic residues extraction from wastewater. In addition, the performed analysis highlights the importance of measuring total concentrations of analytes in whole sample.

MINIATURIZED LIQUID-LIQUID EXTRACTION WITH LOW-TEMPERATURE PARTITIONING TECHNIQUE (LLE/LTP) FOR PESTICIDE ANALYSIS IN A BIOLOGICAL MATRIX BY GAS CHROMATOGRAPHY

The liquid-liquid extraction with low-temperature partitioning technique (LLE/LTP) was miniaturized to determine the pesticides chlorpyrifos, bifenthrin, λ-cyhalothrin, and deltamethrin in a biological matrix, by gas chromatography. The method was proposed for fetal-bovine serum samples (500 μL), by using a full factorial design (23) with one center point. The evaluated factors included the volume of water added to the sample (1000 μL), volume of extraction solvent (500 μL) and stirring time (60 s) – a cleanup step was not necessary. The method was validated for the main figures of merit. The results indicated that the LLE/LTP/GC/ECD miniaturized method was efficient in extracting pesticides from blood-serum samples (75 to 115%). It showed both selectivity and sensitiveness, with limits of quantification (LOQ) ranging from 8 at 17 μg L-1. Once validated, the method was applied to blood-serum samples of rural workers from a city in the Brazilian state of Minas Gerais. In that case, the presence of chlorpyrifos was detected in two of the samples.

Multivariate optimization of low-temperature cleanup followed by dispersive solid-phase extraction for detection of Bisphenol A and benzophenones in infant formula

A simple and effective analytical method to determine six contaminants, including five benzophenones (BP, BP-1, BP-3, BP-8, and BP-12) and bisphenol A (BPA) in infant formulas was developed in this study. For this, a sequential experimental design was used to optimize the extraction and cleanup method using low temperature partition (LTP) combined with dispersive solid phase extraction (dSPE). The effect of primary secondary amine (PSA), sodium chloride (NaCl), graphitized carbon black (GCB), octadecyl (C18), strong anion exchanger (SAX), water, acetonitrile (ACN) and, ultrasound (US) time were evaluated using a sequential design of experiments including a Plackett-Burman, a central composite rotatable design, and the Derringer and Suich's tool. The method was validated, and it showed a limit of quantification varying from 0.06 to 2 mg.kg-1, good precision (< 20% RSD), and recovery (52-106%). The method proposed was applied to twenty-five samples of commercial infant formulas.

Development of a simple multiresidue extraction method for the quantification of a wide polarity range list of pesticides and transformation products in eggs by liquid chromatography and tandem mass spectrometry.

Waterfowl populations have been decreasing in Europe for the last years and pollution appears to be one of the main factors. This study was conducted to develop a single sensitive and robust analytical method for the monitoring of 2 fungicides, 15 herbicides, 3 insecticides and 24 transformation products in wild bird eggs. One of the major challenges addressed was the characterization of chemicals with large logP range (from -1.9 to 4.8). A total of 11 different extraction parameters were tested in triplicate to optimize the extraction protocol, on generic parameters, buffer addition and use of clean-up steps. Quantification was based on matrix-match approach with hen eggs as reference matrix (34 analytes with r²>0.99). Particular attention was payed to matrix effects (-28% on average), quantification limits (0.5 to 25ng.g-1 dry mass / 0.2 to 7.5ng.g-1 fresh mass) and extraction yields (46 to 87% with 25 analytes up to 70%) to ensure the relevance of the method and its compatibility with ultra-trace analysis. It led to a simple solid/liquid low temperature partitioning extraction method followed by LC-MS/MS. Analysis of 29 field samples from 3 waterfowl species revealed that eggs were slightly contaminated with pesticides as only one egg presented a contamination (terbutryn, herbicide, 0.7ng.g-1) and confirmed the relevance of the method.