Ultrasonic Solid-liquid Extraction Research Articles

Development of an Atmospheric Pressure Chemical Ionization Interface for GC-MS.

A closed atmospheric pressure chemical ionization (APCI) ion source as interface between a gas chromatograph (GC) and a triple quadrupole mass spectrometer (QqQ-MS) was developed. The influence of different ion source conditions, such as humidity, make-up gas flow, and the position of the GC column, were investigated and determined as main factors to increase sensitivity and repeatability of the system. For a performance test under real conditions, the new APCI ion source was used for the determination of plant protection products in commercially available coffee beans from Vietnam. The ionization behavior was investigated and the majority of the analytes were detected as [MH]+, [M]+∙, or as characteristic fragment ions, which have been assigned to ion source fragmentation. The developed GC-MS methods are based on tandem MS (MS/MS) and revealed for the plant protection products limits of detection (LOD) between 1 and 250 pg on column and relative standard derivations for all compounds < 16%. The used ultrasonic solid–liquid extraction yielded recovery rates of approximately 60 to 100%. Residues of herbicide methyl esters, organophosphorus compounds, and organonitrogen compounds have been detected in the analyzed coffee beans.

Multiresidue analytical method for the determination of 41 multiclass organic pollutants in mussel and fish tissues and biofluids by liquid chromatography coupled to tandem mass spectrometry.

In this work, the full optimisation and validation procedure to analyse a wide set of emerging organic contaminants in biotissues (mussel and fish muscle, liver, gills and brain) and biofluids (fish plasma and bile) is described. The target families include artificial sweeteners, industrial products, hormones, pharmaceutical and personal care products, pesticides and phytoestrogens. Different clean-up strategies (hydrophilic-lipophilic-balanced (HLB) solid-phase extraction, Florisil solid-phase extraction and liquid-liquid extraction followed by HLB solid-phase extraction and microextraction based on polyethersulfone polymer) were evaluated for the clean-up of focused ultrasonic solid-liquid extraction (FUSLE) extracts before the analysis by liquid chromatography-triple quadrupole tandem mass spectrometry (LC-QqQ-MS/MS). The methods afforded satisfactory apparent recovery values (71-126%) using isotopically labelled analytes and matrix-matched calibration approach, regardless of the matrix. Method detection limits in the range of 4-48ng/g and 0.3-111ng/L were obtained for biotissues and biofluids, respectively. The developed method was applied to determine the uptake and tissue distribution in juvenile gilt-head bream (Sparus aurata) during 7days in seawater, and unexpectedly, perfluoro-1-butanesulfonate tended to accumulate in liver and, to a lesser extent, in muscle and gills. Furthermore, real mussel samples collected in the Basque coast were also analysed and the presence of the highly consumed valsartan (7ng/g) and telmisartan (6.8ng/g) compounds in bivalves is reported for the first time here. Graphical abstract ᅟ.

Screening and identification of per- and polyfluoroalkyl substances in microwave popcorn bags.

Liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QToF-MS) was used for the accurate identification (<10ppm) of different polyfluoroalkylphosphates (PAPs) and their intermediate and end degradation products in popcorn bags. Up to 46 per- and polyfluoroalkyl substances (PFASs) and precursors were identified. Moreover, an accurate method based on focused ultrasonic solid-liquid extraction (FUSLE) and a clean-up step with Envi-Carb sorbent was validated and applied to the quantification of 24 PFASs in popcorn bags from over twelve European countries, three American countries and two Asian countries. To the best of our knowledge, this is the first time that identification and quantification of some intermediates of PFAS precursors (different chain length fluorotelomer saturated acids (FTCAs) and fluorotelomer unsaturated acids (FTUCAs)) have been reported. Moreover, different patterns in the microwave popcorn bag composition were observed within the countries; while in European and American countries short chain PFASs were detected, Asian countries still use long chain PFASs.

Method development and validation for the determination of polybrominated diphenyl ether congeners in Brazilian aquatic sediments

An analytical method was developed and validated for the determination of nine PBDE congeners (BDE 28, 47, 66, 85, 99, 100, 138, 153 and 154) in aquatic sediment samples using ultrasonic solid-liquid extraction (acetone:n-pentane 1:1v/v) followed by gas chromatography coupled with electron capture detection. Values for LOD varied between 0.58 and 0.96ngg−1 while LOQ ranged from 1.92 to 3.21ngg−1. Fortified and certified reference sediments were investigated for method accuracy and precision. Recovery, varying from 87.7±6.6% (BDE-138) to 98.7±1.4% (BDE-28), was influenced by strong hydrophobic interactions between analytes and the sediment matrix. The validated method was successfully used to assess PBDE levels in a Brazilian sediment sample collected at the Paranoá Lake, in Brasília (Brazil). Results revealed environmental concentrations above the reported LOQ for two of the nine PBDE congeners being the BDE-66 the most prevalent (8.1±0.4ngg−1) followed by BDE-47 (2.51±0.02ngg−1). Further investigations are still needed to evaluate the contamination pattern of PBDE in Brazilian sediments, notably in urbanized regions.

Determination of tricyclic antidepressants in biota tissue and environmental waters by liquid chromatography-tandem mass spectrometry.

This work describes the optimization, validation, and application in real samples of accurate and precise analytical methods to determine tricyclic antidepressants (TCAs), including amitriptyline, nortriptyline, imipramine, and clomipramine in different environmental matrices, such as water (estuary, seawater, and wastewater treatment plant effluent) and biota (fish muscle, fish liver, and mussels), which would lead to supplement the scarce information on the presence of TCAs in aquatic organisms. The analysis step performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was fully optimized to improve the sensitivity of the separation and detection steps. The extraction of solid samples was accomplished using focused ultrasonic solid-liquid extraction (FUSLE), which required a low amount of sample (0.5 g), solvent (7 mL acetonitrile/H2O, 95:5 v/v) and short extraction time (30 s). In the optimisation of the clean-up step, mixed mode solid-phase extraction (SPE) using a strong cation exchanger rendered clean extracts and the best results in terms of extraction efficiency and matrix effect. The same SPE mode was also used for the extraction and pre-concentration of TCAs from environmental water matrices. The methods afforded satisfactory apparent recovery values (86-122%) and repeatability (RSD < 5%), regardless of the matrix. Finally, the developed methods were applied to the analysis of real samples from the Biscay Coast, where TCAs were detected in both water and biota samples up to 25.9 ng/L and 1.8 ng/g, respectively. Up to our knowledge, this is the first work using FUSLE for the determination of TCAs and one of the few analyzing TCAs in biota samples.

Simultaneous determination of a variety of endocrine disrupting compounds in carrot, lettuce and amended soil by means of focused ultrasonic solid–liquid extraction and dispersive solid-phase extraction as simplified clean-up strategy

The present study is focused on the development of an analytical method based on focused ultrasonic solid–liquid extraction (FUSLE) followed by dispersive solid-phase extraction (dSPE) clean-up and liquid chromatography–triple quadrupole tandem mass spectrometry (LC–MS/MS) optimised for the simultaneous analysis of certain endocrine disrupting compounds (EDCs), including alkylphenols (APs), bisphenol A (BPA), triclosan (TCS) and several hormones and sterols in vegetables (lettuce and carrot) and amended soil samples. Different variables affecting the chromatographic separation, the electrospray ionisation and mass spectrometric detection were optimised in order to improve the sensitivity of the separation and detection steps. Under the optimised extraction conditions (sonication of 5min at 33% of power with pulse times on of 0.8s and pulse times off of 0.2s in 10mL of n-hexane:acetone (30:70, v:v) mixture using an ice bath), different dSPE clean-up sorbents, such as Florisil, Envi-Carb, primary-secondary amine bonded silica (PSA) and C18, or combinations of them were evaluated for FUSLE extracts before LC–MS/MS. Apparent recoveries and precision in terms of relative standard deviation (RSDs %) of the method were determined at two different fortification levels (according to the matrix and the analyte) and values in the 70–130% and 2–27% ranges, respectively, were obtained for most of the target analytes and matrices. Matrix-matched calibration approach and the use of labelled standards as surrogates were needed for the properly quantification of most analytes and matrices. Method detection limits (MDLs), estimated with fortified samples, in the ranges of 0.1–100ng/g for carrot, 0.2–152ng/g for lettuce and 0.9–31ng/g for amended soil were obtained. The developed methodology was applied to the analysis of 11 EDCs in both real vegetable bought in a local market and in compost (from a local wastewater treatment plant, WWTP) amended soil samples.

Extraction Procedures and GCxGC-TOFMS Determination of Fatty Acids (FAs) in Cyanobacteria Cultures and the Effect of Growth Media Iron Concentration Variation on Cellular FAs Composition

Cyanobacteria biomass obtained from freshwater bodies is known to contain a large amount of fatty acids. Thus, the current need to produce large amount of lipids for different application has identified cyanobacteria as one of the important sources of fatty acids. However, the production of fatty acids and the characteristics of its composition is a function of nutrients. This paper therefore, reports on the efficient extraction procedures of fatty acids from cyanobacteria biomass using ionic liquid solvent and organic solvent under ultrasonic solid liquid extraction technique and the effect of the variation of iron concentration in the growth media on the fatty acids composition of cyanobacteria biomass. The determination of fatty acids composition was performed using gas chromatography coupled to a time-of-flight mass spectrometer (GCxGC-TOFMS). The obtained fatty acids composition was found to be dominated by tetradecanoic acid (C14:0), hexadecanoic acid (C16:0), 7-hexadecenoic acid (C16:1), pentadecanoic acid (C15:0), 6,9,12,15-octadecatetraenoic acid (C18:4), γ-6,9,12-octadecatrienoic acid (γ-C18:3), 9,12,15-octadecatrienoic acid (C18:3), 9,12-octadecadienoic acid (C18:2), 9-octadecenoic acid (C18:1) and octadecanoic acid (C18:0). Statistically it was proved that the ionic liquid extraction protocol and that of ultrasonic solid liquid extraction by organic solvent were not significantly different. It was also revealed that the total amount of fatty acids in cultured cyanobacteria increased with decrease in iron concentration in the growth medium.

Study of the Fate of Lipophilic Wood Extractives During Acid Sulphite Pulping Process by Ultrasonic Solid-Liquid Extraction and Gas Chromatography Mass Spectrometry

Lipophilic extractives in dissolving pulp are still a big concern for pulp industries due to their detrimental effect on the quality of pulp. Since lipophilic extractives remaining in pulp are trapped in low-accessible fiber structures, effective extraction methods need to be established for studying their fate in the process. A simple, ultrasonic, solid liquid extraction established in this study was found to be more effective in capturing extractive residues in all “elemental chlorine-free” bleaching stages. Its efficiency was dependent on the extraction temperature, time, and solvent composition. A linearly correlated removal pattern of sterols and unsaturated fatty acids by the bleaching sequence was observed. It was further found that the bleaching combination did not fully remove lipophilic extractives. This study suggests an opportunity to explore ultrasonication-based extraction as an effective extraction procedure prior to gas chromatography mass spectrometry analysis for monitoring extractives in pulp.

Determination of bisphenol-type endocrine disrupting compounds in food-contact recycled-paper materials by focused ultrasonic solid–liquid extraction and ultra performance liquid chromatography-high resolution mass spectrometry

Focused ultrasonic solid–liquid extraction (FUSLE) and reverse-phase ultra performance liquid chromatography (UPLC) coupled to a quadrupole-time of flight mass spectrometer (Q-TOF-MS) was applied to the determination of bisphenol-type endocrine disrupting compounds (EDCs) in food-contact recycled-paper materials. Recycled paper is a potential source of EDCs. Bisphenol A (BPA), bisphenol F (BPF) and their derivatives bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE) are used for the production of epoxy resins employed in the formulation of printing inks. The FUSLE of bisphenol-type EDCs from packaging is reported for the first time. First, different extraction solvents were studied and methanol was selected. Then, the main FUSLE factors affecting the extraction efficiency (solvent volume, extraction time and ultrasonic irradiation power) were studied by means of a central composite design. The FUSLE conditions selected for further experiments were 20ml of methanol at ultrasonic amplitude of 100% for 5s. Finally, the number of extraction cycles necessary for complete extraction was established in two. The analysis of the FUSLE extracts was carried out by UPLC-Q-TOF-MS with electrospray ionization and the determination of the four analytes took place in only 4min. The FUSLE and UPLC-ESI-QTOF-MS method was validated and applied to the analysis of different food-contact recycled-paper-based materials and packaging. The proposed method provided recoveries from 72% to 97%, repeatability and intermediate precision under 9% and 14%, respectively, and detection limits of 0.33, 0.16, 0.65 and 0.40μg/g for BPA, BPF, BADGE and BFDGE, respectively. The analysis of paper and cardboard samples confirmed the presence of EDCs in these packaging.

Determination of UV filters in packaging by focused ultrasonic solid–liquid extraction and liquid chromatography

A focused ultrasonic solid–liquid extraction (FUSLE) and high performance liquid chromatography (HPLC) with a diode array detector (DAD) is proposed for the determination of ten fat-soluble UV filters in packaging. FUSLE technique is relatively new and has been used for the extraction of a few analytes; such as polycyclic aromatic hydrocarbons and other organic pollutants. In this work, it has been demonstrated that FUSLE is a useful, fast and simple extraction methodology for UV filters because the complete extraction was carried out with just 6 ml of tetrahydrofuran and in only one cycle of 30 s. The developed method has been validated and applied to the analysis of polyethylene-based multilayer packaging samples. The FUSLE-based method allows the sensitive detection of most of the UV-filters in polyethylene, with limits of detection between 0.4 and 8.5 ng mg −1 (except for BDM). Intra and inter-day relative standard deviation values were below 5 and 14%, respectively, except for MBP. In addition, the proposed method was more efficient than tetrahydrofuran extraction under reflux for 2.5 h for all the analytes except for EMT and BDM. Therefore, the developed method can be used to establish the absorption capability of different types of packaging and this information will be very useful in packaging selection.

Simultaneous extraction of several persistent organic pollutants in sediment using focused ultrasonic solid-liquid extraction

Focused ultrasonic solid-liquid extraction (FUSLE) has been optimised for simultaneous analysis of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), phthalate esters (PEs), and nonylphenols (NPs) in sediment samples. Optimisation was performed using naturally polluted freeze-dried sediment samples. The variables studied during the optimisation process were: percentage of maximum power (10-60%), extraction time (10-300 s), number of cycles (1-9), composition of the extraction solvent (acetone-n-hexane, 10:90-90:10), and sample mass (0.1-1 g). The volume of the extractant was constant (10 mL) and the extraction was performed at 0 degrees C in an ice-bath during the optimisation process. All these variables were studied using an experimental design approach by means of The Unscrambler software. The extraction time and the operational variables (number of cycles and power) had no statistically significant effect in the extraction and they were held at 2 min, 20% power, and seven cycles, respectively. The mass and the addition of non-polar solvent (n-hexane) had a negative effect in the extraction yield and, thus, the mass was held at 0.5 g and pure acetone was used as extraction solvent. After those variables were optimised, the effect of the extraction temperature (0 degrees C or room temperature) was also studied. The validation of the extraction method was performed using NIST-1944 reference material in the case of PAHs and PCBs. Because no certified reference sediment is available for PEs and NPs, the results obtained for FUSLE were compared with those obtained for microwave-assisted extraction (MAE) under conditions optimised elsewhere. In all the cases the analysis were performed by gas chromatography-mass spectrometry (GC-MS). Good accuracy were achieved in all cases. The limits of detection (LODs) obtained were between 0.10 and 1.70 ng g(-1) for PAHs (except for naphthalene 5.33 ng g(-1)), 0.02 and 0.16 ng g(-1) for PCBs, 46 and 188 ng g(-1) for PEs, and 0.6 and 12.4 microg g(-1) for NPs. The precision was around 5-10% for most of the PAHs and PCBs and around 2-10% for most of the PEs and NPs.

Micro-focused ultrasonic solid–liquid extraction (μFUSLE) combined with HPLC and fluorescence detection for PAHs determination in sediments: optimization and linking with the analytical minimalism concept

Analytical minimalism is a concept that deals with the optimization of all stages of an analytical procedure so that it becomes less time, cost, sample, reagent and energy consuming. The guide-lines provided in the USEPA extraction method 3550B recommend the use of focused ultrasound (FU), i.e., probe sonication, for the solid–liquid extraction of Polycyclic Aromatic Hydrocarbons, PAHs, but ignore the principle of analytical minimalism. The problems related with the dead sonication zones, often present when high volumes are sonicated with probe, are also not addressed. In this work, we demonstrate that successful extraction and quantification of PAHs from sediments can be done with low sample mass (0.125 g), low reagent volume (4 ml), short sonication time (3 min) and low sonication amplitude (40%). Two variables are here particularly taken into account for total extraction: (i) the design of the extraction vessel and (ii) the solvent used to carry out the extraction. Results showed PAHs recoveries (EPA priority list) ranged between 77 and 101%, accounting for more than 95% for most of the PAHs here studied, as compared with the values obtained after soxhlet extraction. Taking into account the results reported in this work we recommend a revision of the EPA guidelines for PAHs extraction from solid matrices with focused ultrasound, so that these match the analytical minimalism concept.

Discussion of parameters associated with the ultrasonic solid–liquid extraction for elemental analysis (total content) by electrothermal atomic absorption spectrometry. An overview

Ultrasonic solid–liquid extraction (USLE) of trace metals from biological and environmental samples and its subsequent quantification by electrothermal atomic absorption spectrometry (ET-AAS) is nowadays an emerging methodology in the analytical laboratory. However, this methodology is far from maturity as can be readily demonstrated from the controversial data reported by different workers. In the light of our own experience and a survey of published data, a general approach for USLE-ET-AAS is discussed, taking into account the different variables which affect ultrasonic solid–liquid extraction, namely, the ultrasonic device chosen for ultrasonic extraction (e.g. ultrasonic bath or ultrasonic probe), particle size, acid concentration, sonication time and sonication amplitude, sample mass and analyte-matrix binding.