Sample Preparation Method For Determination Research Articles

Development of Green and Facile Sample Preparation Method for Determination of Seven Neonicotinoids in Fresh Vegetables, and Dissipation and Risk Assessment of Imidacloprid and Dinotefuran.

A facile procedure for extracting and determining seven neonicotinoids was developed. Water was the only extraction solvent without phase separation and cleanup steps. The method was validated according to European Union standards, and the values obtained were compared with the criteria. The accuracy values were between 99.8% (thiamethoxam) and 106.8% (clothianidin) at the spiking levels of 0.01, 0.1, and 1 mg/kg in the tested matrices. The precision as pooled RSD values was ≤6.1% (intra-day) and ≤6.9% (inter-day). The limit of quantification was set and tested at 0.01 mg/kg. The matrix effect was evaluated, and all matrices had a suppressive effect. The matrix of the cucumber was the most effective, with -20.9% for dinotefuran and an average of -9.8% for all compounds, while the tomato matrix had the slightest effect. Real marketed samples were analyzed using the developed and QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) methods; the results were not significantly different. A supervised field trial was conducted in the open field to study the dissipation patterns of imidacloprid and dinotefuran in tomatoes. The dissipation of both compounds followed first-order kinetics. The half-life (T½) values were 3.4 and 2.5 days, with dissipation rates k of 0.2013 and 0.2781 days, respectively. Following the EU-MRL database, the calculated pre-harvest interval (PHI) values were 7 and 14 days for imidacloprid and dinotefuran, respectively, and 3 days for both compounds following Codex Alimentarius regulations. The risk of imidacloprid and dinotefuran residues was estimated from chronic and acute perspectives. The risk factors of dinotefuran were lower than those of imidacloprid. Nonetheless, the highest expected residues of both compounds were below the tolerance limits.

Sugaring-out: a novel sample preparation method for determination of fucoxanthin in Icelandic edible seaweeds

Fucoxanthin is an oxygenated carotenoid with a broad spectrum of bioactivities, ranging from antioxidant activity to antimicrobial activities. Micro-algae are well-recognized resources for their production of fucoxanthin, which can be enhanced by cell culture and genetic engineering, and macro-algae or seaweeds are readily available natural resources for harvesting and fucoxanthin purification. Prior sample preparation methods from macro-alga matrix are tedious and time-consuming, usually involving repetitive chromatographic purification of fucoxanthin from co-extracted compounds, such as phlorotannins. This study focused on five Icelandic edible seaweeds and reported a novel sample preparation method—sugaring-out for the HPLC analysis of fucoxanthin. We aimed to determine fucoxanthin contents in Icelandic edible seaweeds and to evaluate the effects of drying process on fucoxanthin contents. An aqueous acetonitrile model system was developed to visualize fucoxanthin partition and to select optimal conditions for partition. Glucose was added to trigger phase separation. The highest yield of fucoxanthin was found when it is mixed with 70 mg mL−1 glucose. Among three edible dry seaweeds sold in Icelandic food market, fucoxanthin was detected only in sugar kelp (18.76–38.13 μg g−1 d.w.). Fresh brown algae can be good alternative sources of fucoxanthin (177.74–227.39 μg g−1 d.w. in Ascophyllum nodosum and 120.39–147.86 μg g−1 d.w. in Fucus vesiculosus). Seaweed freshness is critical for fucoxanthin extraction, as post-harvest drying process with light and air exposure can cause approximately 70–90% loss of fucoxanthin after a 4-week drying process.

A Simple, Fast, and Green Oil Sample Preparation Method for Determination of Cannabidioloic Acid and Cannabidiol by HPLC-DAD

Currently, the medical use of food supplements containing Cannabis sativa has attracted the interest of consumers, as well as the medical and scientific community. With the increasing consumption of these products, there is also a risk of their abuse or discrepancy between the actual and declared contents of active substances by the manufacturer in these products. Thus, the development and elaboration of analytical procedures for determination of appropriate phytocannabinoids seems to be important. This work focuses on the development of a simple, fast and environmentally friendly liquid-liquid extraction method combined with fat freezing from an oil sample to isolate two phytocannabinoids: cannabidiol (CBD) and cannabidiolic acid (CBDA). The extraction method was optimized considering efficacy and repeatability of extraction, as well as minimalizing use of organic reagents and sample amount. Under the optimized conditions, extraction recovery for CBD was 97.3–109% and for CBDA was 69.1–69.5% with precision (RSD, %) 5.0–8.4 and 7.1–10.6, respectively. The evaluated main analytical parameters of the developed high pressure liquid chromatography with diode array detector (HPLC-DAD) method for both studied cannabinoids are satisfactory. The usability of the developed method was checked by analysis of real samples of a food supplement–hemp oil enriched with CBD.

Development of sample preparation method for organochlorine pesticides analysis in soil samples

OCPs are the persistent organic pollutants which are highly toxic to the environment and can accumulate in humans by foods such as rice, vegetable, and fruits. The aim of this research was to develop a rapid and easy sample preparation method for determination 4 OCPs, aldrin, dieldrin, β-endosulfane, and p-p' DDT in soil samples by gas chromatography with electron capture detection. The analysis was performed by using HP-5 capillary column with the isothermal condition at 250 oC and carrier gas flow rate of 1 mL/min. The results show that the 4 OCPs and internal standard, pentachloronitrobenzene, were analyzed within 6 min. The optimized condition of the sample preparation method was using ultrasonic assisted solvent extraction with 20 mL of hexane and ethyl acetate (9:1 v/v) as an extractant for 15x2 min. The results obtained from the proposed sample preparation method have demonstrated that the limit of detection was 0.628–3.68 μg kg-1. Percent recoveries were in the range of 81.42 to 110.7% and RSD were 1.68–9.43%. Correlation coefficients of calibration graphs were more than 0.99. The developed sample preparation method exhibited simplicity rapid and low chemical reagent consumption with satisfactory results.

Magnetic nano-carbon core shell as potent mixed hemimicelle solid phase extraction strategy for determination of acrylamide from potato chips coupled by high-performance liquid chromatography

Magnetic nano-carbon core shell was applied as mixed hemimicelle magnetic solid phase extraction adsorbent to introduce a novel sample preparation method for determination of acrylamide from potato chips. Acrylamide is identified as neurotoxic, a probable human carcinogen (group 2A) compound. Effective extraction parameters such as type and amount of extracting solvent, type and amount of adsorbent, time of extraction and desorption, the effect of pH, time of ionic liquid loading on the adsorbent and stirring rate (rpm) were studied and optimized. Under optimized extraction conditions, a good linearity was observed in the concentration range of 100–1500 ng/g. Limit of detection was observed as 30 ng/g. Application of the proposed method was surveyed by analysis of some potato chips brands available in the local supermarkets. The satisfactory results with the recovery of 95.58% revealed that the proposed method could be applied in food analysis laboratories.

Air-assisted liquid–liquid microextraction combined with flame atomic absorption spectrometry for determination of trace Pb in biological and aqueous samples

ABSTRACT A fast, inexpensive, environmental-friendly and efficient sample preparation method for determination of trace amounts of Pb2+ ions in aqueous samples and humane urine is presented. Lead was extracted using the air-assisted liquid–liquid microextraction (AALLME) technique and determined by flame atomic absorption spectrometry (FAAS). O, O-diethyl dithiophosphoric acid was used as a chelating agent to form a hydrophobic complex. Several factors influencing the microextraction efficiency and the complex formation such as extraction solvent type and its volume, pH, concentration of the chelating agent and extraction time were evaluated. Under optimum conditions, the calibration graph was linear in the concentration range of 30–350 μg L−1 with a detection limit of 8.5 μg L−1. The relative standard deviation for six replicated measurements of 140 μg L−1 of Pb2+ was 4.07%. Obtained enrichment factor was 25. Through combination of AALLME with FAAS, the analytical performance of FAAS for the detection of lead greatly improved. The accuracy of the developed method was evaluated by the analysis of the certified reference material and addition recovery test. The presented method was able to analyse lead in different real samples including human urine, wastewater and water samples with satisfactory recovery ranged from 95% to 108%.

Pesticides in fine airborne particles: from a green analysis method to atmospheric characterization and risk assessment

The intensive use of pesticides such as herbicides, insecticides, fungicides and acaricides has been lead to ubiquitous contamination, being present not only in soils, water bodies and/or crops, but also in the atmosphere. Considering the massive amount of pesticides employed globally, together to their persistence, this may be an important concern regarding air quality and human health worldwide. In the present study we developed a green sensitive sample preparation method for determination of nine organophosphates, two pyrethroids, one carbamate, and one strobirulin in PM2.5 collected in a tropical coastal area in the Southern Hemisphere for the first time. Extraction of PM2.5 sample masses, as low as 206 µg, were performed in a miniaturized device using 500 μL of a mixture containing 18% acetonitrile in dichloromethane followed by sonication for 23 minutes and injection into GC-MS. A total of 12 pesticides were identified and quantified successfully, among them, eight banned pesticides. A risk assessment exposure and cancer risk for possible carcinogenic pesticides (bifenthrin, malathion, parathion and permethrin) were performed for exposure of adults, children and infants. Hazard Quotient and cumulative exposure for organophosphate and pyrethroid pesticides were less than 1, showing that cumulative risk is within acceptable range.

MSPD as sample preparation method for determination of selected pesticide residues in apples

Abstract A method for extraction and fast gas chromatographic (GC) determination of twenty pesticide residues of different volatility and polarity at ultratrace concentration level in apples is presented. Apples as representatives of non-fatty food were chosen as a matrix; they are also a common raw material for baby food production. Under fast GC conditions employing a mass spectrometric detector (MSD), several parameters of the MSPD procedure were optimised. Samples were homogenised with sorbent Florisil, pesticides were eluted with the optimised volume of etylacetate. After solvent evaporation to dryness, reconstitution of the rest to toluene follow and the final extract was injected. Recoveries obtained at three selected concentration levels were determined. The optimised procedure led to recoveries ≥ 90 % for the majority of the studied pesticides and the limits of quantification (LOQs) < 5 μg.kg-1. Repeatability of gas chromatography-mass spectrometry (GC-MS) measurements of the matrix matched standards, expressed as the relative standard deviation (RSD [%]), was in most cases acceptable for ultratrace concentration levels of pesticide residues.

Optimization of QuEChERS sample preparation method for acrylamide level determination in coffee and coffee substitutes

Modification of QuEChERS sample preparation method for the determination of acrylamide (2-propeneamide, AA) in coffee (roasted and instant) and coffee substitutes via silylation has been reported. The AA level after conversion to N,O-bis-(trimethylsilyl)acrylamide (BTMSA) was determined with gas chromatography/ion-trap mass spectrometry in a single ion monitoring mode (GC-SIM-MS). A sample of instant coffee was used to develop an analytical method in the optimisation experiment, which involved the selection of the most suitable sorbents for the dispersive solid phase extraction (d-SPE) clean-up. The usefulness of the method has been verified based on the recovery ratio of acrylamide (fortified samples analysis). Seven variants of the method were tested. The obtained results showed that the best recovery of 95% was obtained using a combination of PSA and SAX sorbents with the addition of hexane in the initial step of extraction. The chosen method was applied for the AA determination in 17 roasted, 10 instant and 8 coffee substitutes samples. The results of acrylamide content ranged from 17.7±1.4 to 776.1±8.8μgkg−1 in roasted coffee, from 96.4±1.7 to 346.5±10.9μgkg−1 in the case of instant coffee, and finally from 70.0±6.0 to 188.9±0.1μgkg−1 in the samples of coffee substitutes. The obtained results are in good agreement with previous literature reports.

Comparison of sample preparation methods for determination of free carbon in boron carbide by X-ray powder diffraction

Several sample preparation methods were evaluated for determination of free carbon in boron carbide powders by quantitative X-ray diffraction method, including ultrasonication, wet ball milling and dry ball milling–wet mixing. Quantitation was based on measuring the integral peak area ratio of the diffraction lines of graphite (002) to boron carbide (012) in samples spiked with pure graphite. The dry milling–wet mixing method provided the best precision and accuracy in all the measurements as well as in determination of free carbon in a boron carbide reference material. There was a linear relationship between the integral peak area ratios and graphite added to boron carbide samples which were purified from their free carbon content. The method provided a low detection limit of 0.05 wt% free carbon.

A faster sample preparation method for determination of polonium-210 in fish

In order to facilitate Health Canada’s study on background radiation levels in country foods, an in-house radio-analytical method has been developed for determination of polonium-210 (210Po) in fish samples. The method was validated by measurement of 210Po in a certified reference material. It was also evaluated by comparing 210Po concentrations in a number of fish samples by another method. The in-house method offers faster sample dissolution using an automated digestion system compared to currently used wet-ashing on a hot plate. It also utilizes pre-packed Sr-resin® cartridges for rapid and reproducible separation of 210Po versus time-consuming manually packed Sr-resin® columns.

Evaluation of six sample preparation methods for determination of trace metals in lubricating oils using inductively coupled plasma-optical emission spectrometry

Quantification of trace elements in used lubricating oil forms a vital part in monitoring engine conditions and impact on the environment. In this study, inductively coupled plasma-optical emission spectrometry (ICP-OES) was employed for the determination of Ag, Ba, Cu, Mn and Ni in used lubricating oils. Methodology was developed so as to minimize the oil’s carbonaceous matter and its effect on viscosity.Accordingly, six oil sample preparation techniques (xylene dilution, detergent emulsion, microwave digestion, dry-ashing, wet-ashing and ultrasonic extraction) were investigated for their efficiency. Optimization of the factors influencing ultrasonic-assisted extraction and ICP-OES operating parameters enabled quantification of the trace metals in oils. Limits of detection (3 S b /m), in the ng g –1 range, were obtained for each element of interest using each method investigated. The validity of the methodologies studied was confirmed through the analysis of quality control (QC) samples. Analyte recoveries, ranging from 48.3 to 106 %, were obtained. Evaluation of the analytical methods studied with regard to accuracy, precision, LOD, linearity, applicability for routine analysis, preparation time and cost was made. Based on these evaluations, ultrasonic extraction has a clear advantage in terms of accuracy, applicability for routine analysis, time and cost of sample preparation. KEYWORDS Lubricating oil, ICP-OES, optimization.

Sample Preparation Methods for Pesticides Analysis in Food Matrices and Environmental Samples by Chromatography-Based Techniques: A Review

Much attention has been made in pesticide analysis to improve agricultural productivity and control these compounds in food and environmental samples. Different methods have been applied in pesticide analysis, among these; methods based on chromatographic separation with mass spectrometric detection have been extremely useful methods for determination of pesticide residues. Despite employing of powerful instrumental techniques, the risk of interference increases with the complexity of the matrix studied, so sample preparation prior to instrumental analysis is necessary. This article reviews the analytical characteristics of the different sample preparation methods for determination of pesticide residues in food and environmental samples and biological fluids, moreover this study describes advantages, disadvantages and details on the analytical characteristics of the procedure that have been applied recently in different sample preparation methods and their application s in combination with chromatographic mass spectrometric analysis. This article provides selection of a reliable method which will be useful for the quantitative analysis of pesticide residues in variety of samples based on their evaluation in recent applications.

Solvent Bar Microextraction with HPLC for Determination and Protein-Binding Characteristics of Oleanolic Acid and Ursolic Acid

An improved solvent bar microextraction (SBME) combined with HPLC was applied to rapidly determine oleanolic acid (OA) and ursolic acid (UA) in Chinese medicinal herbs (CMHs), and to investigate drug–protein binding. Variables influencing SBME were investigated and optimized. Under optimal conditions, the linear ranges of 3.6–1,820 ng mL−1 for OA and 4.2–2,080 ng mL−1 for UA were obtained with square correlation coefficients of 0.9996 and 0.9997, respectively. The detection limits were 1.3 ng mL−1 for OA and 1.5 ng mL−1 for UA. The relative standard deviations were lower than 9.4 %. The protein-binding rates, the numbers of binding sites, and the binding constants of OA and UA were also obtained via the method. It has been demonstrated that SBME can not only be a simple, rapid and efficient sample preparation method for determination of active components from CMHs but also be a potential research protocol for protein-binding interactions.

Carbon nanotube assisted sol-gel based hollow fiber solidphase microextraction combined with pre-heating injectionhigh performance liquid chromatography as a novel sample preparation method for determination of nitroaromatics

Carbon nanotube assisted sol-gel based hollow fiber solidphase microextraction combined with pre-heating injectionhigh performance liquid chromatography as a novel sample preparation method for determination of nitroaromatics

Sample preparation methods for determination of Cd, Pb and Sn in meat samples by GFAAS: use of acid digestion associated with a cold finger apparatus versus solubilization methods

The aim of this study was to present three sample preparation methods for the determination of Cd, Pb and Sn in meat by Graphite Furnace Atomic Absorption Spectrometry (GFAAS): acid digestion, solubilization with tetramethylammonium hydroxide and formic acid. For the digestion with HNO3, a conventional open system with a cold finger was used. This system helped to avoid losses of analytes and reagents by volatilization, permitting to operate at high temperatures applied at a digester block and reducing the digestion time (∼1 h). Solubilizations were performed at room temperature. The slurry was left standing overnight and remained closed until achieving complete solubilization. The temperature program of the graphite furnace was optimized for each element in the different means of preparation samples using a mixture of Pd–Mg. The figures of merit were similar for all sample preparation methods evaluated. The limits of detection obtained for the acid digestion procedure were 0.0006, 0.0164 and 0.0520 μg g−1 for Cd, Pb and Sn, respectively. In order to evaluate the accuracy of the results obtained by the three sample preparation methods, recovery tests for four real meat samples were performed and the recoveries ranged from 93.7 to 109%, supporting the accuracy of the method. Also, different certified reference materials of meat were analyzed and the results obtained were in agreement with the certified value at 95% of confidence (t-test). The best results were obtained by the acid digestion procedure with the cold finger system. This procedure is faster, the system is semi-closed with no significant contamination or loss of analytes by volatilization and it provides a better signal/noise ratio.

Energy-dispersive X-ray fluorescence spectrometry combined with dispersive liquid–liquid microextraction for simultaneous determination of zinc and copper in water samples

A dispersive liquid–liquid microextraction technique was successfully used as a sample preparation method for determination of trace amounts of zinc and copper ions in surface water by energy-dispersive X-ray fluorescence spectrometry (EDXRF). The extraction method is based on the formation of sparingly soluble in water complexes of Zn and Cu with 2-(5-bromo-2-pyridylazo)-5-diethylamino-phenol (5-Br-PADAP). Some effective parameters of extraction and complex formation, such as extraction and disperser solvent type and their volume, pH, concentration of the chelating agent, and salt effect, have been optimized. Under the optimum conditions, the enrichment factor 250 was obtained from only 5 mL of a water sample. The calibration graph was linear from 0.02 to 0.4 μg mL−1 with detection limits of 1.8 ng mL−1 and 1.7 ng mL−1 for copper and zinc, respectively. The total RSD values for the EDXRF determination of Cu and Zn ions were 6.7% and 6.9%. Taking into account all steps preceding the determination and the uncertainty of EDXRF, the proposed method can be recognized as precise. The accuracy and repeatability of the proposed procedure were checked by the standard addition method and compared to the results obtained using the ICP-OES technique. The recovery in the range 91–95% was satisfactory and indicated the usefulness of the developed procedure.

Pressurized Liquid Extraction Combined with Dispersive Liquid‐liquid Micro‐extraction as an Efficient Sample Preparation Method for Determination of Volatile Components in Tobacco

AbstractThe pressurized liquid extraction (PLE) followed by dispersive liquid–liquid micro‐extraction (DLLME) has been developed for extraction of volatile components in tobacco. 35 volatile components were detected by gas chromatography mass spectrometry (GC‐MS). Methanol–methyl tert‐butyl ether (MTBE) (8:2, v/v) was selected as PLE extraction solvent. The optimized DLLME procedure, 3 mL of pure water and 1.0 mL tobacco extract solution, 40 μL of chloroform as extraction solvent, 0.5 mL of acetonitrile as disperser solvent, was validated. Under the optimum conditions, the enrichment factors were in the range of 96‐159. The limits of detection were between 0.14 and 0.33 μg/kg. The repeatability of the proposed method, expressed as relative standard deviation, varied between 4.3 and 7.5% (n = 6). The recoveries of the analytes evaluated by fortification of tobacco samples were in the range of 84.7‐96.4%. Compared with the conventional sample preparation method for determination of volatile components in tobacco, the proposed method was quick and easy to operate, and had high‐enrichment factors and low consumption of organic solvent.

Optimization of supercritical fluid extraction combined with dispersive liquid–liquid microextraction as an efficient sample preparation method for determination of 4-nitrotoluene and 3-nitrotoluene in a complex matrix

Supercritical fluid extraction (SFE) combined with dispersive liquid–liquid microextraction (DLLME) followed by gas chromatography with flame ionization detector (GC-FID) was developed for the extraction and determination of 4-nitrotoluene and 3-nitrotoluene in soil sample. The effects of different SFE experimental parameters on the extraction recovery were studied simultaneously using a central composite design (CCD) after a 2n−1 fractional factorial experimental design. The variables of interest in SFE were pressure, temperature, modifier volume, and dynamic extraction time. From this statistical evolution the pressure, dynamic extraction time, and modifier volume were found to have significant effects on the results achieved from SFE-DLLME-GC-FID, while temperature was not statistically significant at a 95% confidence level. The optimal SFE conditions for 4-nitrotoluene and 3-nitrotoluene were a pressure of 350atm, temperature of 35°C, dynamic extraction time of 30min and modifier volume of 150μL. Under the optimal conditions, the extraction calibration plots were linear in the range of 0.25–25mgkg−1 and the limits of detection (LODs) were 0.12mgkg−1 for both of the analytes. Performance of the present method was evaluated for extraction and determination of 4-nitrotoluene and 3-nitrotoluene in soil samples, and satisfactory results were obtained (RSDs<6.5%).

Development of Two Sample Preparation Methods for Determination of Lead in Composite Dust Wipe Samples

Abstract Sample preparation methods for four-wipe composite dust wipe samples, used by nine different laboratories accredited under the U.S. Environmental Protection Agency (EPA) National Lead Laboratory Accreditation Program (NLLAP), were evaluated to select two methods most likely to provide the best overall performance among multiple laboratories, based on accuracy, precision and practicality of the methods. The best performing methods involved (1) hot nitric acid/hydrogen peroxide digestion and (2) nitric acid ultrasonication. In a second round of testing, two sets of composite dust wipe samples with known amounts of lead were submitted blind to each of the nine laboratories to be prepared for analysis using these two sample preparation methods. Results showed that both methods are capable of meeting all EPA NLLAP requirements for accuracy (recovery) and precision. The ultrasonication method had superior performance at lower cost.