Matrix-matched Solutions Research Articles

Rapid and safe determination of vitamin B1 in dairy products, fruits, nuts and vitamin tablets: Combination of natural deep eutectic solvents, experimental design and artificial intelligence

A natural deep eutectic solvent-based sonication assisted liquid-phase microextraction (NDES-SA-LPME) combined with UV-Vis spectrophotometry was optimized for the analysis of thiamine (Vit-B1) in dairy products, fruits, nuts and vitamin tablets. Five NADES was prepared by blending different molar ratios of hydrogen bond acceptors (citric acid, malic acid, tartaric acid, choline chloride and betaine) and hydrogen bond donors (glucose, proline, and glycerol). Based on preliminary experiments, the central composite design was created for optimization of selected key extraction factors. The effects of factors on the extraction of Vit-B1 were investigated using artificial intelligence approaches. Validation of the NDES-SA-LPME method was performed by analysis of reference materials. Working ranges for model solutions and matrix matched solution were 8–500 µg L−1 and 15–400 µg L−1, respectively. Further, limits of detection for model solutions and matrix matched solution were 2.4 µg L−1 and 4.6 µg L−1, respectively. Finally, a matrix matching calibration approach was used to increase recovery results, and acceptable recovery data were obtained in range of 95.9%-118.4%. This study is the first report to apply artificial intelligence, experimental modelling and NDES together to the analysis of Vit-B1 in real samples.

Optimization of a fast and sensitive method based on matrix solid-phase dispersion-LC-ms/ms for simultaneous determination of phthalates and bisphenols in mussel samples

Bisphenols and phthalates are wide classes of endocrine disrupting chemicals (EDCs) extensively used as additives in plastic products. In this study, a fast and reliable analytical method based on matrix solid-phase dispersion (MSPD) coupled with LC-MS/MS was developed and optimized for simultaneous determination of 8 bisphenols and 7 phthalates in raw mussel extract. The LC-MS/MS method was tested for linearity (R2), inter- and intra-day repeatability, limit of detection and quantification, both for matrix-free and matrix-matched solutions. The MSPD method was optimized in terms of ratio between sample and sorbent, and the type and quantity of the eluents in order to maximize the recoveries and to minimize matrix effects. The obtained recoveries (values between 75% and 113%), limits of detection (values between 0.048 and 0.36 µg kg−1), limits of quantification (values between 0.16 and 1.28 µg kg−1), repeatability (RSD% between 1.30% and 8.41%) and linearity (R2 > 0.998) were satisfactory and suitable for the determination of target micropollutants in food samples. In addition, the low solvent consumption and fast execution make this method ideal for routinely determinations of bisphenols and phthalates in mussels.

Rapid screening of 84 pesticide residues in dendrobium by Sin-QuEChERS Nano purification column with gas chromatography-tandem mass spectrometry

利用Sin-QuEChERS Nano净化柱结合气相色谱-串联质谱(GC-MS/MS)分析,建立了石斛基质中84种不同极性农药残留的快速筛查方法。比较了采用不同的提取溶剂(1%乙酸乙腈、丙酮)和不同的提取方式(加水浸泡和不加水浸泡)下目标物的提取效率。利用金钗石斛样品系统比较了Sin-QuEChERS Nano法与经典的基质固相分散法(dSPE)、固相萃取法(SPE)、QuEChERS法的净化效果及提取回收率,以及净化效果较好的Sin-QuEChERS Nano法与dSPE法基质效应的差异。目标物经DB-1701MS石英毛细管色谱柱(30 m×0.25 mm×0.25 μm)程序升温分离,GC-MS/MS多反应监测(MRM)模式检测,基质匹配溶液外标法定量。通过GC-MS/MS检测方法对金钗石斛和铁皮石斛中的84种代表性农药进行了方法学验证。结果表明:各目标物在不同范围内呈良好的线性相关,相关系数(r2)均>0. 990,方法的检出限(LOD, S/N=3)为1.5~5.8 μg/kg,方法的定量限(LOQ, S/N=10)为5.0~15.0 μg/kg。在两个水平下,目标农药的加标回收率为68.7%~116.2%,相对标准偏差(RSD, n=6)均低于15%。与其他经典的前处理方法相比,Sin-QuEChERS Nano法在净化效果方面表现更好,该法不仅可以有效去除色素、有机酸、碱性干扰物等物质,还可以节省样品制备时间,避免溶剂转移造成的损失,无需进一步涡旋或离心,是一种简单而有效的提取物纯化程序。该方法灵敏、快速、简便、可靠,有效地提高了石斛中农药快速筛查时的检测效率,具有较强的实际应用价值。此外,所开发的方法可以进一步扩展目标农药的类型,并可以用于检测其他更多食品及中药材中的农药残留。

Development and validation of modified QuEChERS methods for the analysis of fipronil and its metabolites in chicken meat

A sensitive method for the precisely and accurate determining the presents of fipronil and its metabolites in chicken meat was developed and validated using a modified quick, easy, cheap, effective, rugged and safe approach coupled with gas chromatography-mass spectrometry analysis. The solvent acetonitrile was used for the extraction of the samples with the salt phases composed of sodium chloride and magnesium sulphate, and then in the second phase used C18 and anhydrous magnesium sulphate. The linearity of the analytical response across the studied range of concentrations (0.005-0.050 mg kg-1) was excellent, obtaining correlation coefficients higher than 0.99. The average recoveries of the pesticide ranged from 75 to 106% for fortification levels of 0.005, 0.01 and 0.05 mg kg-1. The precision values associated with the analytical method, expressed as RSD values, were less than 11.15%. Matrix-matched solutions were also prepared by serially diluting the intermediate solution with blank chicken meat sample extracts containing none of the tested analytes to perform matrix-matched calibration with the same concentrations as in the solvent. The validated method was used to analyse the target compounds in 30 real samples imported from European countries. The present of fipronil-desulfinyl metabolite was confirmed in four samples.

Magnetic particles encoding a suspension probe for ultra-sensitive and quantitative determination of atrazine

As a highly toxic and widely used herbicide, atrazine poses a serious threat to food safety as well as overall environmental and human health. Due to complex matrix interference and the difficulty of signal enrichment, there is an urgent need for a convenient, fast, and ultrasensitive method that detects trace atrazine without concern for matrix effects. Here, we provide the first account of a sensitive and rapid suspension probe based on magnetic microspheres used to detect atrazine in herbs. The self-made magnetic beads featured -COOH groups and were used as the carrier to construct immunofluorescent probes. These probes then conjugated with the atrazine antigen through an activated ester method, ultimately binding to the antibody. Homogeneous detection was ensured using flow cytometry and the microflow optical channel along with allophycocyanin-conjugated goat-anti-mouse secondary antibody (APC-IgG-SecAb) as the fluorescent signal. The magnetic suspension probe allowed for high target enrichment and the inherent two-dimensional selective detection of flow cytometry effectively avoided any matrix interference. This method had good linearity across 1.69−23.19 ng mL−1. The IC50 and LOD values were 4.81 ng mL−1 and 0.95 ng mL−1, respectively; the sensitivity was increased three-fold relative to ELISA. After complete optimization, 2-N-morpholinoeth-anesulfonic acid was used as the coupling solution and maintained good mono-dispersity, stability, and reactivity for the labelled microspheres during the process. The entire experiment was simple, and effectively used reagents; moreover, both the labor required and detection time were greatly reduced. Critically, the strategy presented here greatly reduced interference from complex matrices, and saved preparation for matrix-matched solutions when different herbs were screened. Overall, this strategy was sensitive, rapid, eco-friendly, and labor-saving; collectively, these attributes make it well-suited for on-site screening of atrazine contamination and will allow for increased food safety.

Multiresidue Pesticides Analysis of Vegetables in Vietnam by Ultrahigh-Performance Liquid Chromatography in Combination with High-Resolution Mass Spectrometry (UPLC-Orbitrap MS).

An ultrahigh-performance liquid chromatography in combination with high-resolution mass spectrometry Thermo Q-Extractive Focus Orbitrap MS has been introduced for analysis of multiclass pesticides in vegetable samples collected in Hanoi, Vietnam. Multiclass pesticides were separated on the Thermo Hypersil Gold PFP column utilizing a gradient of the mobile phase consisting of 5 mM ammonium formate, 0.1% formic acid in deionized water, and methanol. The target analytes were detected in the full-scan mode on Thermo Scientific Q-Exactive Focus Orbitrap MS for quantitation at the optimum operating conditions. These conditions included, but not limit to, the resolution of 70000 at the full width at half maximum in both positive and negative mode, mass range from 80 to 1000 m/z, and optimized parameters for the heated electrospray ionization source. The identification of the analytes in real samples was based on retention times, mass to charge ratios, mass accuracies, and MS/MS spectra at the confirmation mode with the inclusion list of target analytes. The mass accuracies of target analytes were from −4.14 ppm (dinotefuran) to 1.42 ppm (cinosulfuron) in the neat solvent and from −3.91 ppm (spinosad D) to 1.29 ppm (cinosulfuron) in the matrix-matched solution. Target analytes in the vegetable-based matrix were extracted by the QuEChERS method. Some critical parameters of the analytical method such as linearity, repeatability, limit of detection, and limit of quantitation have been evaluated and implemented. Excellent LOD and LOQ of the developed method were achieved at the range of 0.04–0.85 and 0.13–2.9 μg·kg−1, respectively. Intraday and interday repeatability of the analytical signal (peak area, n=6) of the developed method were below 3% and 10%, correspondingly. The matrix effect, extraction recovery, and overall recovery were fully investigated by spiking experiments. Experimental results demonstrated that the ionization suppression or enhancement was the main contribution on the overall recoveries of target analytes. Finally, the in-house validated method was applied to pesticides screening in vegetables samples in local villages in Hanoi, Vietnam. The concentrations of all target analytes were below limit of quantitation and lower than US-FDA or EU maximum residue levels.

Ochratoxin A in the Portuguese Wine Market, Occurrence and Risk Assessment

ABSTRACTOchratoxin A (OTA) is mainly found in cereals and cereal-based foodstuffs, but also in wine. Being one of the most consumed alcoholic drinks in Portugal and one of the main sources of human exposure to OTA, wine monitoring and exposure studies are essential. The analytical methodology consisted of the direct injection of the filtered samples into the liquid chromatograph, equipped with fluorescent detection (LC-FLD). Linearity was adequate, both in mobile phase and in matrix-matched solutions, with R2 values higher than 0.997. The limits of detection were 0.08 and 0.39 µg/L for white and red wine, respectively and recoveries were above 91.9%. One hundred wine samples acquired on the Portuguese market were investigated. In 5 samples the OTA was detected, with the red wine presenting higher frequency of contamination. Regarding the risk to human health it was observed that the estimated weekly intake (EWI) is considerably lower than the established tolerable weekly intake (TWI).

Group detection of DON and its modified forms by an ELISA kit

ABSTRACTDeoxynivalenol (DON) and its modified forms (3-, and 15-acetyl-DON, DON-3-glucoside) are commonly analysed by chromatographic methods. Indeed, coupled with proper extraction and clean-up, LC-MS represents the best approach for multi-mycotoxin measurements. On the other hand, immunochemistry-based methods are possibly able to detect a family of structurally related compounds, although the determination of single contributions is not possible so far. However, ELISA methods often lead to an apparent overestimation of the mycotoxins content because modified forms and matrix components can potentially cross-react with the antibodies (designed for the parent toxin). Several data about the possible cross-reactivity of commercial DON-detecting ELISA kit are reported in the literature so far. Data are commonly obtained in buffer solutions or in matrix-matched solutions, but comparison of a set of naturally incurred samples has never been reported. In the present work the accuracy of a commercial DON-detecting ELISA kit was evaluated on naturally incurred soft wheat (n = 15) and maize (n = 15), taking into account the matrix effect. Recovery was calculated considering the DON concentration found by LC-MS/MS and the total DON concentration, expressed as the sum of DON and its modified forms found by LC-MS/MS. The obtained data clearly show that, when 3-modified forms of DON occur in the sample, the ELISA kit does actually detect them, thus returning an apparent overestimation if only DON content is considered. When the ELISA recovery is calculated on the total DON content, the accuracy of the analysis increases and the variability decreases. According to our data, the ELISA kit seems to be a promising group detection tool for the accurate evaluation of DON and its modified forms, expressed as sum of DON, DON-3Glc and 3Ac-DON, for soft wheat and maize samples.

Determination of trace rare earth elements in gadolinium aluminate by inductively coupled plasma time of flight mass spectrometry

An analytical methodology was developed for the precise quantification of ten trace rare earth elements (REEs), namely, La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, and Tm, in gadolinium aluminate (GdAlO3) employing an ultrasonic nebulizer (USN)-desolvating device based inductively coupled plasma mass spectrometry (ICP-MS). A microwave digestion procedure was optimized for digesting 100mg of the refractory oxide using a mixture of sulphuric acid (H2SO4), phosphoric acid (H3PO4) and water (H2O) with 1400W power, 10min ramp and 60min hold time. An USN-desolvating sample introduction system was employed to enhance analyte sensitivities by minimizing their oxide ion formation in the plasma. Studies on the effect of various matrix concentrations on the analyte intensities revealed that precise quantification of the analytes was possible with matrix level of 250mgL−1. The possibility of using indium as an internal standard was explored and applied to correct for matrix effect and variation in analyte sensitivity under plasma operating conditions. Individual oxide ion formation yields were determined in matrix matched solution and employed for correcting polyatomic interferences of light REE (LREE) oxide ions on the intensities of middle and heavy rare earth elements (MREEs and HREEs). Recoveries of ≥90% were achieved for the analytes employing standard addition technique. Three real samples were analyzed for traces of REEs by the proposed method and cross validated for Eu and Nd by isotope dilution mass spectrometry (IDMS). The results show no significant difference in the values at 95% confidence level. The expanded uncertainty (coverage factor 1σ) in the determination of trace REEs in the samples were found to be between 3 and 8%. The instrument detection limits (IDLs) and the method detection limits (MDLs) for the ten REEs lie in the ranges 1–5ngL−1 and 7–64μgkg−1 respectively.

Hierarchical Cluster Analysis of Matrix Effects on 110 Pesticide Residues in 28 Tea Matrixes

Matrix effects on 110 pesticides in 28 tea matrixes of different varieties and origins by LC/MS/MS were studied, and most of the pesticides exhibited soft and medium signal suppression. To better understand the influence of the tea varieties and the physicochemical characteristics of pesticides on the matrix effects, the multivariate analysis tool called hierarchical cluster analysis was applied. Tea matrixes were grouped into three clusters: unfermented, fermented, and post-fermented teas. Any type of tea can be chosen from each cluster as a corresponding representative matrix within that cluster to make matrix-matched solutions, which could simplify analysis while guaranteeing its accuracy. Matrix effects on most pesticides were similar despite the physicochemical diversities of the pesticides.

Matrix effects in the simultaneous determination of fenicol antibiotics in swine muscle and casings by ultra performance liquid chromatography-tandem mass spectrometry

Animal tissue samples were extracted with ethyl acetate or alkalized ethyl acetate, and purified with MCX or LC-18 solid-phase extraction columns, and the matrix effects (ME%) in the simultaneous determination of four fenicol antibiotics including chloramphenicol (CAP), thiamphenicol (TAP), florfenicol (FF), and florfenicol amine (FFA) were studied by ultra performance liquid chromatography-tandem mass spectrometry. ME% for FFA in swine muscle and casings extracted by ethyl acetate with LC-18 column cleanup were 11.1% and 10.4%, and in swine muscle extracted by ethyl acetate and alkalized ethyl acetate with MCX column cleanup ME% were 8.1% and 16.1%, respectively, showing strong signal suppression; while ME% for FF in swine muscle extracted by ethyl acetate and alkalized ethyl acetate with LC-18 column cleanup were 148.5% and 146.9%, and in swine muscle extracted by ethyl acetate and alkalized ethyl acetate with MCX column cleanup were 234.3% and 150.9%, showing strong signal reinforcement. Deuterated chloramphenicol-d5 could only be used as an internal standard to eliminate matrix effects for CAP determination. It may be that the most effective method to eliminate matrix interference in the simultaneous determination of the four analytes is quantified by using matrix-matched solutions. Under the optimum conditions of sample pretreatment and quantitative analysis, the decision limits (ccα as specified in European Directive 2002/657/EC) for FFA, TAP, CAP and FF in swine muscle were determined to be 0.4, 0.05, 0.02 and 0.02 μg kg−1, and 0.5, 0.1, 0.04 and 0.03 μg kg−1 in casings; the detection capabilities in swine muscle were determined to be 0.7, 0.09, 0.05 and 0.05 μg kg−1, and 1.2, 0.19, 0.12 and 0.07 μg kg−1 in casings, respectively.

A Direct Method for Quantification of Lead and Cadmium Content in Biological Fluids of the Human Reproductive System

The aim of this work was to quantify lead and cadmium content in follicular fluid and sperm from couples under in vitro fertilization therapy after developing a procedure for direct determination of such metals in those matrices by electrothermal atomic absorption spectrometry with a minimum sample pretreatment, using palladium/magnesium as chemical modifier. Samples were diluted and a particular temperature program for each analyte was followed. Several variables such as pyrolysis and atomization temperatures, diluent and dilution proportion, and modifier mass and linearity were studied in order to achieve optimal conditions. Methodologies took into account sensitivities and sensitivity ratios aiming for lower limits of detection (3σ) and quantification (10σ) and no matrix effects. Calibration against matrix matched solutions was mandatory for both matrices and metals. Accuracy of the results was verified by analysis of standard reference materials for lead and cadmium in blood and serum as well as in-house control materials as reference follicular fluid and sperm were not available. Results have shown a high degree of agreement between experimental and expected values according to Student's t-test (95% confidence level). Concentration ranges (µg L−1) for cadmium and lead found were 0.64–0.99 and 0.61–1.72 in follicular fluid while those levels in sperm ranged from 0.16–0.40 and ≤0.40–1.63, respectively. Our findings were similar to those reported by other studies.

金属系生体材料評価のための溶出試験おける疑似体液中微量元素の分析

For characterization of corrosion resistance of metallic biomaterials, determination of trace amounts of metallic ions released from the materials in static immersion into simulated body fluids were investigated. In a pre-treatment method by sulfuric acid, sensitive, precise and accurate determination of the trace metallic elements in simulated body fluids could be performed by an inductively coupled plasma-optical emission spectrometry. For accurate analysis, it was necessary to employ a matrix-matched solution for the calibration. Moreover, usage of a vessel made of tetrafluoro ethylene-perfluoro alkylvinyl ether copolymer in the static immersion test was recommended for the prevention of contamination. Thus, it was possible to determine μg dm-3 order of elements in simulated body fluids and evaluate nano-gram order of the released metallic ions.

Trace Analysis of Released Metallic Ions in Static Immersion Test for Characterization of Metallic Biomaterials

For characterization of corrosion resistance of metallic biomaterials, determination of trace amounts of metallic ions released from the materials in using static immersion into simulated body fluids (SBF) were investigated. In using a H2SO4-fume pre-treatment method, sensitive, precise and accurate determination of the trace metallic elements in SBFs could be performed by ICP-OES. For accurate analysis, it was necessary to employ a matrix-matched solution for the calibration. Moreover, usage of a PFA vessel in the static immersion test was recommended for the prevention of contamination. Thus, it was possible to determine μg dm−3 (ppb) order of elements in SBFs and evaluate nano-gram order of the released metallic ions.

Application of cobalt ammine complexes for the simultaneous determination of traces of As, Fe, Ti, V and Zr in high-purity cobalt metal by lanthanum hydroxide coprecipitation and inductively coupled plasma-atomic emission spectrometry.

Co is not coprecipitated with lanthanum hydroxide in ammonium hydroxide solution due to the formation of soluble salts of cobalt ammine complexes. This complexation reaction has been applied to the simultaneous determination of five trace impurities (As, Fe, Ti, V and Zr) in high-purity Co metal by inductively coupled plasma-atomic emission spectrometry. Warming the solution and double coprecipitation are effective for separating the trace elements simultaneously from a large amount of cobalt ammine complexes. Matrix-matched solutions are used for calibration. The detection limits of the five elements are in the range of 0.06 and 0.6 microg/g and the recoveries are quantitative.

Effect of easily ionizable elements on solutions and slurries in an axially viewed inductively coupled plasma

A Perkin-Elmer Optima 3000 axially viewed ICP spectrometer was used to study the effects of EIEs on the spatially dependent ion and atom emission intensities from Mg containing solutions and slurries. Using the Mg 279.553 nm ion and 285.213 nm atom line emission profiles, ion:atom emission intensity ratios were measured, with and without EIEs, across the plasma to visualize the changes in energy transfer processes when an EIE is present. Transport effects are negated when this ion:atom/ion:atom ratio is employed. In the presence of an EIE, both atom line ratios and ion line ratios are enhanced for solutions and slurries and this enhancement increases in the order Li < Na ⩽ K < Cs. Profiles of ionEIE:ion and atomEIE:atom ratios show greater enhancement for the excited ion population that the excited atom population. This indicates an increased departure from simple ‘Saha’ LTE conditions for both solutions and slurries with EIEs. While similar energy transfer processes are seen for solutions and slurries, under these matrix conditions, the magnitude of the enhancement in slurries is less than that of solutions when Li and Na are present. A reduced atomization efficiency for slurries relative to the matrix-matched solutions is implied. This relative atomization efficiency is seen to change for different systems. A refractory MgO slurry, which contained particles up to 4 µm in diameter, gave a relative atomization efficiency of 80–85% in the absence of an EIE. In the presence of an EIE, the relative efficiency increased up to 100% in the order Li < Na ≈ K ≈ Cs. This effect may be attributed to (i) a ‘real’ increase in atomization efficiency, (ii) subtle changes in the rejection of a larger solid particle fraction or (iii) a combination of both. Atom line ratio profiles show spatially dependent structure, similar to a ‘caldera’, when EIEs are present. The rim of this atom caldera is the interface between the central analyte channel and the plasma body. These profiles allow the energy transfer processes that occur in this region to be visualized. The presence of EIEs causes this region to be enhanced and increase in the order, Li < Na ⩽ K < Cs. Ion line profiles are relatively flatter. Ion:atom ratio profiles show that an energy transfer process involving ion population enhancement occurs at the centre of the analyte channel when an EIE is present.