Selective Extraction Method Research Articles

Assessment of a semi-automated protocol for multiplex analysis of sepsis-causing bacteria with spiked whole blood samples.

Sepsis is associated with high morbidity and mortality rates worldwide. Rapid and reliable diagnostic methods are needed for efficient and evidence-based treatment of septic patients. Recently, new molecular tools have emerged to complement the conventional culture-based diagnostic methods. In this study, we used spiked whole blood samples to evaluate together two ready-to-use molecular solutions for the detection of sepsis-causing bacteria. We spiked whole blood with bacterial species relevant in sepsis and extracted bacterial DNA with the NorDiag Arrow device, using the SelectNA Blood pathogen DNA isolation kit. DNA extracts were analyzed by the polymerase chain reaction (PCR)- and microarray-based Prove-it™ Bone and Joint assay, resulting in correctly identified bacterial species with detection limits of 11–600 colony-forming unit/mL (CFU/mL). To understand the recovery losses of bacterial DNA during the sample preparation step and the capability of the PCR- and microarray-based platform to respond to the sensitivity requirements, we also determined the analytical sensitivity of the PCR and microarray platform to be 1–21 genome equivalents for the tested bacterial species. In addition, the inclusivity of the Prove-it™ Bone and Joint assay was demonstrated with methicillin-resistant Staphylococcus aureus (MRSA) clones carrying SCCmec types I, II, IV, or V and a nontypable SCCmec type. The proof-of-concept for accurate multiplex pathogen and antibacterial resistance marker detection from spiked whole blood samples was demonstrated by the selective bacterial DNA extraction method combined with the high-throughput PCR- and microarray-based platform. Further investigations are needed to study the promising potential of the concept for sensitive, semi-automated identification of sepsis-causing pathogens directly from whole blood.

Outcompeting GC for the detection of legacy chlorinated pesticides: online-SPE UPLC APCI/MSMS detection of endosulfans at part per trillion levels

Endosulfan, the last remaining organochlorine pesticide, has been the subject of a number of international regulations and restriction/banning action plans worldwide. Occurrence of endosulfan residues in South Florida environments has been widely described in the literature for more than two decades. This work describes a selective, sensitive, and fast online solid-phase extraction (SPE) method coupled with liquid chromatography separation and tandem mass spectrometry (LC-MS/MS) for the determination of endosulfan isomers and endosulfan sulfate in water samples at low part per trillion levels with very little sample preparation. A negative atmospheric pressure chemical ionization source was carefully optimized to produce reproducible spectra of the target compounds with no adduct ion formation. Selected reaction monitoring transitions were monitored and quantitation was performed against a per-deuterated internal standard β-endosulfan (d4). The automated online SPE clean-up was performed using only 20mL of untreated water sample prior to LC-MS/MS analysis. The method was capable of separating and quantifying endosulfan within a 24-min run using acetonitrile and water as mobile phases and presenting statistically calculated method detection limits of 3, 10, and 7ng/L for endosulfan sulfate, α-endosulfan, and β-endosulfan, respectively. In addition, a QuEChERS method was successfully developed and applied for endosulfan determination in sediments/soils, floating and submerged algal mats, and small fish. Minimal matrix effects were observed in all matrices analyzed and recoveries for all analytes ranged from 50-144%. The developed methodology was applied to monitor the occurrence and to assess the potential transport of endosulfan in the Loveland Slough watershed, an area adjacent to Everglades National Park showing long-term contamination with endosulfans.

A one-step extraction/clean-up method for determination of PCBs, PBDEs and HBCDs in environmental solid matrices

A selective pressurized liquid extraction (S-PLE) method was developed for rapid determination of 3 classes of halogenated organic contaminants in indoor dust, soil and sediment samples. The optimised method used 3 : 2 v/v n-hexane-dichloromethane for extraction of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs). Extraction was performed at 90 °C for 5 min followed by 4 min static time under 1500 psi. Good recoveries of target analytes were obtained after 3 extraction cycles. In-cell cleanup was performed using 10 g of 44% H2SO4 acid silica and 5 g of florisil (secondary fat retainer), while copper powder was used to remove elemental sulfur. The method was validated using NIST SRM2585 and SRM 1941b in addition to an in-house previously characterised soil sample. Measured concentrations of target compounds showed good agreement with the certified values with RSD < 20% indicating the good accuracy and precision of the S-PLE method. Clean extracts provided low noise levels resulting in low method detection limits (<0.03 ng g(-1)) and LOQs (<0.1 ng g(-1)). The method developed was applied successfully to real environmental samples and it provided various advantages over traditional methods including reduced solvent consumption and analysis time, minimal sample contamination and high sample throughput which can be beneficial for environmental monitoring programs dealing with large numbers of samples.

HIGH SELECTIVE OIL SHALE MINING

Several extraction technologies have been used for mining oil shale in Estonia. The quality and properties of the raw material for fuel and oil depend directly on the initial geological properties of the mineral resource. In case of kukersite oil shale in Estonia the calorific value, oil yield and limestone content vary. The paper considers possibilities for selective mining of kukersite oil shale based on tests and theoretical studies. Analyses show that selective and high selective mining extraction methods have a potential for increasing oil shale yield and decreasing losses.

Extractive Separation of Cadmium(II) using Cyanex 923 from Ammonium Thiocyanate Medium

A selective and effective solvent extraction method has been developed for the separation of cadmium(II) using Cyanex 923 in toluene. Cadmium(II) was quantitatively extracted using 0.1 M Cyanex 923 in toluene from 1.0 M ammonium thiocyanate media. The extracted cadmium(II) was quantitatively stripped with 3.0 M nitric acid from organic phase and determined spectrophotometrically with PAR at 520 nm. The optimum extraction conditions have been evaluated by studying parameters such as ammonium thiocyanate concentration, Cyanex 923 concentration, equilibration time, various diluents, diverse ions, and stripping agents. The selective and sequential separation of cadmium(II) from other cations was achieved in binary as well as multicomponent mixtures. The method was extended for the separation of cadmium from spent nickel-cadmium batteries, some aquatic plants and zinc blende. The reliability of the method is assured by a comparison of the results with those obtained using AAS.

Application of a selective extraction method for methylmercury compound specific stable isotope analysis (MeHg-CSIA) in biological materials

Methylmercury (MeHg) is a key organometallic compound of Hg and a potent neurotoxin that bioaccumulates along food webs. Hg speciation analysis of environmental samples is essential for understanding the sources, dynamics and impact of MeHg in ecosystems. Hg stable isotope analysis is a new tool to try and answer outstanding questions on Hg cycling, but has thus far been applied essentially to total Hg fractions in biota. Hg compound specific stable isotope analysis is a new approach to understand the isotopic fraction of Hg at the molecular level. In this study, we developed a robust, accurate and precise selective extraction method for MeHg in biological samples for subsequent quantification by AFS or ID-GC-ICPMS and determination of the isotopic composition by CV-MC-ICPMS. The method consists of an optimized two-step extraction/back-extraction technique validated using a MeHg standard solution and seven certified reference materials with a large range of total Hg and MeHg values. In the final extract solution, MeHg purification yields were higher than 97%, and accurate MeHg concentrations were obtained for the different certified materials. High precision MeHg stable isotope analysis (2SD ≈ 0.1‰) by CV-MC-ICPMS showed a four-fold improvement in precision for this method relative to previous on-line GC-MC-ICPMS measurements. Reference values for total Hg and MeHg compound specific stable isotope values are given for NRCC-TORT-2, NRCC-DOLT-4, IRMM-ERM-CE464, IRMM-BCR-463, IRMM-BCR-414, NIST-SRM-1947 and NIST-QC03LH03 reference materials.

Supercritical fluid extraction of carotenoids and chlorophylls a, b and c, from a wild strain of Scenedesmus obliquus for use in food processing

Faster and more selective extraction methods are urged to recover food-grade pigments and antioxidants from microalgae – which do not resort to food-incompatible and environment-unfriendly solvents. Hence, this study ascertained the influence of pressure, temperature, CO2 flow rate and a polar co-solvent upon the yields of carotenoids and chlorophylls in supercritical fluid extraction of Scenedesmus obliquus biomass. The highest carotenoid yield was attained at 250bar and 60°C. The yields of chlorophylls, when using plain CO2, increased slightly with pressure, but decreased with temperature and CO2 flow rate; the highest yield of chlorophyll a was at 4.3gCO2min-1, whereas ethanol as co-solvent increased all yields except that of chlorophyll c. The highest ratio of total carotenoids to chlorophyll a was reached at 250bar and 60°C. A remarkable selectivity was observed under these operating conditions, which may enable easy separation and purification of the aforementioned pigments.

Method of selective HCl and HF extraction from SDW pyrolysis gases

Results are provided for a study of the possibility of selective absorption of HCl and HF from a gas stream also containing H2S and CO2. In order to implement this hydrolysis gas cleaning method, it is proposed to maintain the absorbing solution pH in the range 4–5 by neutralizing excess HCl, for example, by means of adding Ca(OH)2.

Investigation of the kinetic parameters of the process of extraction of nickel (ІІ) hydroxide buffer ammonia and chloride amon

Розраховані кінетичні характеристики комплексу хімічних реакцій, які складають конкретні способи видобування нікелю з вторинної сировини. Наводяться висновки, що важливі для вибору кращого способу з метою його подальшого впровадження у виробництво.

An extract procedure for studying the free and glycosilated aroma compounds in grapes

In this study seven published methods of extraction of skin free and bound volatile compounds have been compared. The free and bound volatiles were separated by solid phase extraction (SPE) and then analysed by gas chromatography coupled with mass spectrometry (GC–MS). The results showed that the extraction of volatile compounds from grapes is highly affected by extraction solution features. The solution at pH 3.2 and 0% ethanol resulted the most effective as it led to the extraction of a higher number and amount of free and glycosilated volatile compounds. The selected extraction method of grape skin and the process of pulp juice were validated for quantitative determination of a wide range of grape aroma compounds. A total of 37 free and bound grape aroma compounds were quantified by GC–MS in selective ion monitoring modality (SIM). Among them, 26 volatile compounds resulted validated in grape skin and pulp juice.

Selective pressurised liquid extraction of halogenated pesticides and polychlorinated biphenyls from pine needles

Pine needles are an ideal matrix for the long-term monitoring of semi-volatile organic compounds in the atmosphere because they are naturally occurring and distributed worldwide. However, typical extraction methods result in the co-elution of matrix-interfering compounds and thus require time-consuming clean-up steps. A selective pressurised liquid extraction method (S-PLE) for extracting current-use pesticides, historic-use pesticides and polychlorinated biphenyls (PCBs) from pine needles that does not require additional clean-up steps was developed and validated. The selective extraction was achieved by packing the extraction vessel with a fat retainer, Florisil, down-stream of the pine needle matrix. A fat to fat-retainer ratio of 0.0057 (corresponding to 35g of Florisil per 10g of pine needle sample) was selected to minimise the co-elution of matrix-interfering compounds. Three 5-min extractions were performed using 25:75 (v/v) dichloromethane:n-hexane and a solvent flush of 150%. The mean recovery of spiked current-use pesticides, historic-use pesticides and PCBs using this method was 71%, 72%, and 84%, respectively. The method was validated by comparing target analyte concentrations measured in a pine needle sample using the optimised S-PLE method to those obtained using a conventional PLE method with external clean-up. The method detection limits and reproducibility were similar for the two methods; however, sample preparation time was 67% shorter when using the S-PLE method.

Selective extraction and preconcentration of chromium using Moringa oleifera husks as biosorbent and flame atomic absorption spectrometry

In this study a new method for selective extraction and preconcentration of chromium in water using Moringa oleifera husks as the solid phase with a flow injection system and detection by flame atomic absorption spectrometry was developed. The behavior of Cr(III) and Cr(VI) adsorption onto Moringa oleifera husks allowed the selective separation of Cr(III) in the pH range of 7–9 and Cr(VI) in the pH range of 1–2. The operational variables of the preconcentration system were optimized through full factorial and Doehlert designs. The limits of detection for Cr(III) and Cr(VI) were 1.92 and 2.45μg L−1 and the precision were below 1.63% and 0.08%, respectively. Results for recovery tests using different water samples were higher than 88% for Cr(III) and 81% for Cr(VI).

Comparison of trace metal adsorption onto different solid materials and their chemical components in a natural aquatic environment

Abstract Solid materials such as suspended particulate matter (SPM), deposited sediment (DS) and natural surface coatings (NSC, composed of biofilms and associated minerals) are important sinks and potential sources of pollutants in natural aquatic environments. Although these materials can exist in the same water body, few studies have been conducted to compare their ability to adsorb trace metals. In this study, the adsorption of Pb, Cu and Cd by these solids, collected from an urban lake, was investigated. In addition, the metal adsorption properties of the main components of these solids, namely Mn and Fe oxides and organics, were also investigated using the method of selective extraction followed by metal adsorption. The solids that co-existed in water showed similarities and differences in their compositions. For each metal, adsorption to the solids occurred in the same order: NSC > SPM > DS. For Pb and Cd, Fe and Mn oxides and organics contributed to the adsorption by NSC and SPM, and the adsorption by DS was dominated by Fe oxides. For Cu, the organics were the main adsorptive phase. The specific adsorption capability of these components decreases in the following order: Mn oxides > Fe oxides > organics. Overall, the results presented herein indicate that different solids and their components played important roles in the adsorption of trace metals.

A new selective liquid membrane extraction method for the determination of basic herbicides in agro-processed fruit juices and Ethiopian honey wine (Tej) samples

Supported liquid membrane (SLM) extraction was optimised for trace extraction and enrichment of selected triazine herbicides from a variety of agro-processed fruit juices and Ethiopian honey wine (Tej) samples. In the extraction process, a 1:1 mixture of n-undecane and di-n-hexylether was immobilised in a thin porous PTFE membrane that forms a barrier between two aqueous phases (the donor and acceptor phases) in a flow system. The extracts constitute the selectively enriched analytes collected from the acceptor phase and were analysed by transferring to a HPLC-UV system using a diode array detector at 235 nm. High enrichment factors were obtained with very good repeatability of results, and the detection limit was lower than 3.00 µg l−1 for ametryn in apple juice. The optimised method showed very good linearity of over 50–500 µg l−1 with a correlation coefficient of >0.990 or better for triplicate analysis. All chromatograms gave well resolved peaks with no interfering peaks at the retention times of the selected triazines, showing high selectivity of the SLM extraction method in combination with HPLC-UV for the selected matrices. The optimised method can be used as an alternative solventless extraction method for microgram-level extraction of other triazine herbicides and a variety of pesticides from liquid and semi-liquid environmental, biological and food matrices.

Master curve of filler localization in rubber blends at an equilibrium state

In this study, the phase-specific localization of filler in NBR/NR blends was characterized by means of the selective extraction method and wetting concept. A strong dependence of silica localization on the filler loading was found. A model based on thermodynamic data was proposed for a quantitative prediction of filler localization in rubber blends. The filler localization can be described by a master curve demonstrating a characteristic behavior in dependence on the filler surface tension data of blend components and filler. The effect of filler loading on the silica localization is sufficiently explained by this model by taking into consideration the deactivation of the silanol groups on the silica surface by adsorbed curing additives. Using the master curve, the surface tension of filler affected by curing additives and silane addition can be estimated that may be useful for evaluation and comparison of the effect of different coupling agents. Surface tension values of different fillers were estimated by means of the master curve and they lie in the same order compared to those reported in literature. A potential transfer of filler within a rubber blend can be also quantitatively predicted.

Determination of polycyclic aromatic hydrocarbons from soil samples using selective pressurized liquid extraction

A selective pressurized liquid extraction (SPLE) method has been optimized for the determination of polycyclic aromatic hydrocarbons (PAHs) in soil samples. The method comprises a fully automated extraction and on-line clean-up procedure by inclusion of sorbents in the extraction cells. The contributing parameters of SPLE including type of solvent, static extraction time, number of extractions, extraction temperature, nature and amount of sorbents were investigated. The optimal extraction was performed at 70 °C for 10 min (static extraction time) cycled once using n-hexane/methylene chloride (50 : 50, v/v) and the sorbents in the extraction cells were 3 g of alumina and 2 g of silica gel. The collected extracts from the cells, after pre-concentration, were clean enough for direct injection into GC-MS. Validation of the SPLE technique was performed, with the recovery rates for 16 PAHs in the range of 75–103%, and the relative standard deviation (RSD) was generally less than 10%. Method detection limits (MDL) were in the ranges of 0.001–0.080 μg kg−1 for the GC-MS analyses. Finally, the method was successfully used to evaluate the cultivated soils in Beijing, China.

Molecularly imprinted polymer for selective extraction of 3-methylflavone-8-carboxylic acid from human urine followed by its determination using zwitterionic hydrophilic interaction liquid chromatography

A novel water-compatible molecularly imprinted SPE combined with zwitterionic hydrophilic interaction liquid chromatography method for selective extraction and determination of 3-methylflavone-8-carboxylic acid (MFA), the main active metabolite of flavoxate in human urine, was developed and validated. The effects of progenic solvents, pH, cross linker and amount of monomer were studied to optimize the efficiency and selectivity. The molecularly imprinted polymer showed good specific adsorption capacity with an optimum of 200 μmol/g at pH 7.5 and selective extraction of MFA from human urine. The recovery of MFA from human urine was >98%. The lower limit of quantification was 1.20 μg/mL. The proposed method overcomes the matrix effects of endogenous substances generally encountered during direct analysis of urine sample.

Metal fractionation of cadmium, lead and arsenic of geogenic origin in topsoils from the Marrancos gold mineralisation, northern Portugal

The Marrancos gold mineralisation has a chemical assemblage of Fe-As-Se-Bi-Au-Ag-Te-(Cu-Pb-Zn-Sn-W). The -200 mesh of 144 topsoil samples was analysed by ICP-MS to determine total contents of 53 elements that include potentially harmful elements like Cd, As and Pb. The soil geochemistry shows that some trace elements occur in considerably high concentrations. On the basis of data for total metal concentrations, 10 topsoil samples were selected to carry out a metal fractionation study using a selective extraction method. A set of four leaches of increasing strength was used sequentially in the soil samples. Across the study area, there is some evidence of past mining and exploration activity, indicating that these soils may be locally disturbed. The shallow mineralised quartz veins were exploited for gold by the Romans. Several galleries were constructed during the 2nd World War, probably for the exploration of quartz-cassiterite-wolframite veins. However, the main mineralised body in depth was never explored. The results of metal fractionation show different partitions for the three elements. Total Cd concentrations in these soils are low, with a median value of 0.1 mg/kg. In average, 12% of total Cd is adsorbed by clays and/or co-precipitated with carbonates, and 19% is bounded to Fe-Mn oxyhydroxides. However, the low concentrations indicate that the metal does not represent an immediate risk to human health. For Pb, metal fractionation shows that, on average, 22% of Pb is adsorbed by amorphous Fe and Mn oxides, but the samples from the northern part of the area have the major fractions of Pb in soluble forms. The low probability of exposure in this part of the study area decreases the risk posed by this heavy metal. Total As concentrations in the Marrancos soils are extremely high. A large area has As concentrations above 1,000 mg/kg. For As, metal fractions in the sulphide phase vary between 84 and 98% in the studied samples. But one sample has 20% of total As in easily reducible forms, corresponding to a partial concentration of 1,800 mg/kg that has a high probability of being bioavailable. The most labile As forms occur at the southern part of the area, where the probability of exposure is higher and the risk of human health increases in the same order. From the three studied potentially harmful elements, As is certainly the element of concern.

HEAVY METAL CONTAMINATION OF SOIL AND RICE IN WASTEWATER-IRRIGATED PADDY FIELD IN A SUBURBAN AREA OF HANOI, VIETNAM

The present paper deals with the heavy metal contamination of soil and rice grain in the paddy field subjected to the irrigation water polluted with wastes from various industrial plants in Hanoi. Soil and rice grain samples were taken at different distances (0-50 m) from the edge of the paddy field. The retention and potential mobility of heavy metals were assessed based on the contents of total and fractionated heavy metals in the soil and their leachability. The concentration of the fractionated heavy metals was determined by selective sequential extraction method. Heavy metal contents in the rice grain were also assessed. The average concentration of the metals in the soil was in the order: Cu (202 mg kg -1 ) > Zn (192 mg kg -1 ). Cr (185 mg kg -1 ) Pb (159 mg kg -1 ) > Ni (45 mg kg -1 ) > Cd (4 mg kg -1 ). The heavy metal concentrations in the soil exceeded the permissible level of the Vietnamese standard for Cd, Cu, Pb and Zn. The results of selective sequential extraction procedure indicated that dominant fractions were oxide, organic and residual materials for Cd, Ni, Pb and Zn, and organic and residual materials for Cr, and an organic material for Cu. Leaching tests with deionized water and acid solutions indicated that the ratio of leached metal concentration to total metal concentration in the soil decreased in the order: Cd > Ni > Cr > Pb > Cu > Zn. By leaching with deionized water and acid solutions, all heavy metals were released fully from exchangeable fraction, and Cd and Ni were fully from carbonate and oxide fractions. The average concentration of heavy metals in the rice grain was in the order: Zn (14.4 mg kg -1 ) > Cu (6.9 mg kg -1 ) > Cr (3.1 mg kw -1 ) > Pb (2.1 mg kg -1 ) > Ni (1.4 mg kg -1 ) > Cd (0.1 mg kg -1 ). The concentrations of Cu, Ni, and Zn in the rice grain met the WHO standard while the concentrations of Cr and Pb exceeded the permissible level of the standard. The concentrations of Cd met the Vietnamese standard while those o.f Pb exceeded the permissible level of the standard. Transfer coefficient for the metals was in the order: Zn > Ni > Cu > Cd ≈ Cr > Pb.

Sample Treatment Based on Extraction Techniques in Biological Matrices

The importance of sample preparation methods as the first stage in bioanalysis is described. In this article, the sample preparation concept and strategies will be discussed, along with the requirements for good sample preparation. The most widely used sample preparation methods in the pharmaceutical industry are presented; for example, the need for same-day rotation of results from large numbers of biological samples in pharmaceutical industry makes high throughput bioanalysis more essential. In this article, high-throughput sample preparation techniques are presented; examples are given of the extraction and concentration of analytes from biological matrices, including protein precipitation, solid-phase extraction, liquid-liquid extraction and microextraction-related techniques. Finally, the potential role of selective extraction methods, including molecular imprinted phases, is considered.