Molecularly imprinted polymer coated solid-phase microextraction fiber prepared by surface reversible addition–fragmentation chain transfer polymerization for monitoring of Sudan dyes in chilli tomato sauce and chilli pepper samples

Surface reversible addition-fragmentation chain transfer (RAFT) polymerization method was firstly applied to the preparation of molecularly imprinted polymer (MIP) coated silicon solid-phase microextraction (SPME) fibers. With Sudan I as template, an ultra-thin MIP coating with about 0.55-μm thickness was obtained with homogeneous structure and controlled composition, due to the controllable radical growing and chain propagation in surface RAFT polymerization. The MIP-coated fibers were found with enhanced selectivity coefficients (3.0–6.5) to Sudan I–IV dyes in contrast with those reported in our previous work. Furthermore, the ultra-thin thickness of MIP coating was helpful to the effective elution of template and fast adsorption/desorption kinetics, so only about 18 min was needed for MIP-coated SPME operation. The detection limits of 21–55 ng L⁻¹ were achieved for four Sudan dyes, when MIP-coated SPME was coupled with liquid chromatography (LC) and mass spectrometry (MS) detection. The MIP-coated SPME–LC–MS/MS method was tested for the monitoring of ultra trace Sudan dyes in spiked chilli tomato sauce and chilli pepper samples, and high enrichment effect, remarkable matrix peaks-removing capability, and consequent high sensitivities were achieved to four Sudan dyes.     

Molecularly imprinted polymer microspheres prepared by Pickering emulsion polymerization for selective solid-phase extraction of eight bisphenols from human urine samples

The bisphenol A (BPA) imprinted polymer microspheres were prepared by simple Pickering emulsion polymerization. Compared to traditional bulk polymerization, both high yields of polymer and good control of particle sizes were achieved. The characterization results of scanning electron microscopy and nitrogen adsorption–desorption measurements showed that the obtained molecularly imprinted polymer microsphere (MIPMS) particles possessed regular spherical shape, narrow diameter distribution (30–60 μm), a specific surface area (S_BET) of 281.26 m² g⁻¹ and a total pore volume (V_t) of 0.459 cm³ g⁻¹. Good specific adsorption capacity for BPA was obtained in the sorption experiment and good class selectivity for BPA and its seven structural analogs (bisphenol F, bisphenol B, bisphenol E, bisphenol AF, bisphenol S, bisphenol AP and bisphenol Z) was demonstrated by the chromatographic evaluation experiment. The MIPMS as solid-phase extraction (SPE) packing material was then evaluated for extraction and clean-up of these bisphenols (BPs) from human urine samples. An accurate and sensitive analytical method based on the MIPMS-SPE coupled with HPLC-DAD has been successfully established for simultaneous determination of eight BPs from human urine samples with detection limits of 1.2–2.2 ng mL⁻¹. The recoveries of BPs for urine samples at two spiking levels (100 and 500 ng mL⁻¹ for each BP) were in the range of 81.3–106.7% with RSD values below 8.3%.     

Enzyme-linked immunosorbent assay (ELISA) using a specific monoclonal antibody as a new tool to detect Sudan dyes and Para red

To set up an immunoassay-based method to detect Sudan dyes and Para red, we generated a monoclonal antibody (Mab) using a specially designed carboxyl derivative of Sudan I (CSD I) as the immunogen. CSD I was synthesized by azocoupling reaction using 2-naphthol and diazotised 4-aminobenzoic acid. The antibody was obtained from a hybridoma, which was derived from the fusion of the mouse myeloma SP2/0 cells and the splenocytes from the mice immunized with the CSD I-bovine serum albumin (BSA) conjugate. In addition, we showed that the Mab was highly specific for Sudan I, III and Para red. The limit of detection was approximately 0.01 ng mL⁻¹ in phosphate-buffered saline (PBS) buffer and 0.5 ng g⁻¹ in chilli tomato sauce. The recoveries of Sudan I, III and Para red for the chilli tomato sauce were from 84% to 99% and coefficients of variation were from 14.9% to 33.3%. Thus, the enzyme-linked immunosorbent assay (ELISA) method is a rapid and high throughput screening tool to detect Sudan dyes and Para red in food products.     

Novel sponge-like molecularly imprinted mesoporous silica material for selective isolation of bisphenol A and its analogues from sediment extracts

Bisphenol A (BPA) imprinted sponge mesoporous silica was synthesized using a combination of semi-covalent molecular imprinting and simple self-assembly process. The molecularly imprinted sponge mesoporous silica (MISMS) material obtained was characterized by FT-IR, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption–desorption measurements. The results show that the MISMS possessed a large specific surface area (850.55 m² g⁻¹) and a highly interconnected 3-D porous network. As a result, the MISMS demonstrated a superior specific adsorption capacity of 169.22 μmol g⁻¹ and fast adsorption kinetics (reaching equilibrium within 3 min) for BPA. Good class selectivity for BPA and its analogues (bisphenol F, bisphenol B, bisphenol E and bisphenol AF) was also demonstrated by the sorption experiment. The MISMS as solid-phase extraction (SPE) material was then evaluated for isolation and clean-up of these bisphenols (BPs) from sediment samples. An accurate and sensitive analytical method based on the MISMS–SPE coupled with HPLC–DAD has been successfully established for simultaneous determination of five BPs in river sediments with detection limits of 0.43–0.71 ng g⁻¹ dry weight (dw). The recoveries of BPs for lyophilizated sediment samples at two spiking levels (50 and 500 ng g⁻¹ dw for each BP) were in the range of 75.5–105.5% with RSD values below 7.5%.     

Enantiomer-specific determination of hexabromocyclododecane in fish by supramolecular solvent-based single-step sample treatment and liquid chromatography–tandem mass spectrometry

A single-step, environmentally friendly sample treatment was developed and used in combination with liquid chromatography–tandem mass spectrometry (LC–MS/MS) for the quantitation of hexabromocyclododecane (HBCD) stereoisomers in fish. It was based on the microextraction of the stereoisomers with a supramolecular solvent (SUPRAS) made up of reverse aggregates of decanoic acid (DeA). The procedure involved the stirring of the fish sample (750 mg) with 600 μL of SUPRAS for five minutes, subsequent centrifugation for extract separation from matrix components and direct analysis of the extract after dilution 1:1 with methanol. Individual enantiomers of α-, β- and γ-HBCD were separated on a chiral stationary phase of β-cyclodextrin and quantified by monitoring of the [M−H]⁻ → Br⁻ transition at m/z 640.9→80.9. Driving forces for the microextraction of HBCD in the SUPRAS involved both dispersion and dipole–dipole interactions. Quantitation limits for the determination of individual HBCD enantiomers in hake, cod, sole, panga, whiting and sea bass were within the intervals 0.5–3.4 ng g⁻¹, 0.9–2.5 ng g⁻¹, 0.6–1.4 ng g⁻¹, 1.0–5.6 ng g⁻¹, 0.8–1.3 ng g⁻¹ and 0.5–3.5 ng g⁻¹, respectively. Recoveries for fish samples fortified at the ng g⁻¹ level ranged between 87 and 114% with relative standard deviations from 1 to 10%. The sample treatment proposed greatly simplifies current procedures for extraction of HBCD stereoisomers and is a useful tool for the development of a large scale database for their presence in fish.     

Determination of commonly used azole antifungals in various waters and sewage sludge using ultra-high performance liquid chromatography–tandem mass spectrometry

Sensitive and reliable methods have been developed and validated for determination of commonly consumed azole antifungal pharmaceuticals (clotrimazole, econazole, ketoconazole, and miconazole) and biocides (propiconazole and tebuconazole) in various waters and sewage sludge. Solid phase extraction (SPE) combined with ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) was used to determine the azole antifungals in waters. Azole antifungals in sewage sludge were extracted with ultrasonic-assisted extraction, followed by SPE cleanup and UHPLC–MS/MS detection. Quantification was performed by internal standard calibration in multiple reaction monitoring mode. Recoveries were mostly in the range of 52–110% with relative standard deviations generally within 20%. Method quantification limits were 0.5–6 ng L⁻¹ in waters and 3–9 ng g⁻¹ dry weight (dw) in sewage sludge, respectively. The methods were applied to determine the azole antifungals in wastewater, river water, sediment, and sewage sludge sampled from the Pearl River Delta, China. Clotrimazole, ketoconazole, and miconazole were widely detected at low ng L⁻¹ in waters, low ng g⁻¹ dw in river sediment, and low μg g⁻¹ dw in sewage sludge. The methods can provide valuable tools for investigating occurrence and fate of the azole antifungals in the environment.     

Determination of pharmaceuticals in soils and sediments by pressurized liquid extraction and liquid chromatography tandem mass spectrometry

The present work describes the development of a sensitive analytical method based on pressurized liquid extraction (PLE) and pre-concentration by solid-phase extraction (SPE), followed by liquid chromatography–electrospray tandem mass spectrometry (LC–ESI-MS/MS) for the determination of seventeen pharmaceuticals in soils and sediments. The method is based on sample homogenisation using Na₂–EDTA washed sand and extraction with water at 90 °C. Special emphasis was placed on the optimization of the extraction procedure to develop a green method that reduces, at a maximum, the use of organic solvents in order to eliminate matrix components during the clean-up. The proposed method was linear in a concentration range from 0.3 to 333 ng g⁻¹, with correlation coefficients higher than 0.993. Method detection (MDLs) and quantification (MQLs) limits ranged from 0.1 to 6.8 ng g⁻¹ and from 0.25 to 23 ng g⁻¹, respectively. Absolute recoveries were analyte dependent, varying between 50% and 105% at the MQL level, except for fenofibrate (40%) and diclofenac (34%). The intra-day and inter-day precision was given by RSD values from 0.7% to 7.9% and from 1.6% to 14.5%, respectively. Acetaminophen, carbamazepine, ciprofloxacin, clofibric acid, codeine, diazepam, fenofibrate, metropolol, ofloxacin and propanolol were detected at concentrations from MDL to 35.62 ng g⁻¹ in soils and sediments from marsh areas. Due to the low recoveries, results for fenofibrate and diclofenac can only be considered as semi-quantitative. The method was fully suitable for the other 15 pharmaceuticals.     

Determination of tetrabromobisphenol-A,tetrachlorobisphenol-A and bisphenol-A in soil by ultrasonic assisted extraction and gas chromatography–mass spectrometry

In this work, an isotope dilution method for the determination, in agricultural and industrial soil samples, of tetrabromobisphenol-A, tetrachlorobisphenol-A and bisphenol-A by gas chromatography–mass spectrometry was developed. The compounds were extracted from soil by sonication assisted extraction in small columns (SAESC) with a low volume of ethyl acetate as extraction solvent. For dirty soil samples, such as industrial soils, a simultaneous clean-up on an acidified Florisil–anhydrous sodium sulfate mixture was carried out to remove interferences. After extraction, solvent was evaporated and analytes were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and determined by isotope dilution gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC–MS–SIM), using ¹³C₁₂ labeled compounds as internal standards. Recoveries from spiked samples were between 88% and 108% and the estimated limits of detection (S/N = 3) varied from 30 pg g⁻¹ to 90 pg g⁻¹. The response obtained with this method was linear over the range assayed, 5–300 ng ml⁻¹, with correlation coefficients equal or higher than 0.999. The validated method was used to investigate the levels of these phenolic compounds in soil samples collected from different locations in Spain. Bisphenol-A was detected in all samples at concentrations from 0.7 ng g⁻¹ to 4.6 ng g⁻¹ in agricultural soils and from 1.1 ng g⁻¹ to 44.5 ng g⁻¹ in industrial soils. Tetrabromobisphenol-A was found in various soil samples at levels in the range of 3.4–32.2 ng g⁻¹ in industrial soils and at 0.3 ng g⁻¹ in one agricultural soil, whereas tetrachlorobisphenol-A was not detected.     

Novel molecularly imprinted polymer prepared by nanoattapulgite as matrix for selective solid-phase extraction of diethylstilbestrol

Using nanoattapulgite as matrix, both diethylstilbestrol surface molecularly imprinted polymer and non-imprinted polymer were synthesized in this work. Compared with each other, the diethylstilbestrol surface molecularly imprinted polymer is superior to non-imprinted polymer in adsorption capacity, selectivity and mass transfer property. The maximum static adsorption capacities of diethylstilbestrol surface molecularly imprinted polymer, non-imprinted polymer and nanoattapulgite for diethylstilbestrol was 105.14, 78.54 and 28.50 mg g⁻¹, respectively. As the packing material of solid-phase extraction, the diethylstilbestrol surface molecularly imprinted polymer has been applied to concentrating diethylstilbestrol in pond water and fish samples. A corresponding analytical method to determine diethylstilbestrol has been developed. The limit of detection for diethylstilbestrol in pond water sample and fish samples were 3 μg L⁻¹ and 15 μg kg⁻¹.     

Determination of chiral pharmaceuticals and illicit drugs in wastewater and sludge using microwave assisted extraction,solid-phase extraction and chiral liquid chromatography coupled with tandem mass spectrometry

This is the first study presenting a multi-residue method allowing for comprehensive analysis of several chiral pharmacologically active compounds (cPACs) including beta-blockers, antidepressants and amphetamines in wastewater and digested sludge at the enantiomeric level. Analysis of both the liquid and solid matrices within wastewater treatment is crucial to being able to carry out mass balance within these systems. The method developed comprises filtration, microwave assisted extraction and solid phase extraction followed by chiral liquid chromatography coupled with tandem mass spectrometry to analyse the enantiomers of 18 compounds within all three matrices. The method was successfully validated for 10 compounds within all three matrices (amphetamine, methamphetamine, MDMA, MDA, venlafaxine, desmethylvenlafaxine, citalopram, metoprolol, propranolol and sotalol), 7 compounds validated for the liquid matrices only (mirtazapine, salbutamol, fluoxetine, desmethylcitalopram, atenolol, ephedrine and pseudoephedrine) and 1 compound (alprenolol) passing the criteria for solid samples only. The method was then applied to wastewater samples; cPACs were found at concentration ranges in liquid matrices of: 1.7 ng L⁻¹ (metoprolol) – 1321 ng L⁻¹ (tramadol) in influent, <LOD (desmethylcitalopram and metoprolol) – 506 ng L⁻¹ in effluent, and in solid matrix digested sludge: 0.4 ng g⁻¹ (metoprolol) – 275 ng g⁻¹ (citalopram). Enantiomeric profiling revealed that studied compounds were present in analysed samples in non-racemic composition. Furthermore, enantiomeric composition of studied analytes differed in liquid and solid matrices. This demonstrates that not analysing the solid fraction of wastewater may lead to over-estimation of the removal rates of cPACs as well as possible misrepresentation of the enantiomeric fraction of the compounds as they leave the wastewater treatment plant. Consequently risks from cPACs entering the environment might be higher than anticipated.     

Development of an analytical methodology for the determination of the antiparasitic drug toltrazuril and its two metabolites in surface water,soil and animal manure

This paper presents the development, optimization and validation of a LC–MS/MS methodology to determine the antiparasitic veterinary drug toltrazuril and its two main metabolites, toltrazuril sulfoxide and toltrazuril sulfone, in environmental surface water, soil and animal manure. Using solid phase extraction and selective pressurized liquid extraction with integrated clean-up, the analytical method allows for the determination of these compounds down to 0.06–0.13 ng L⁻¹ in water, 0.01–0.03 ng g⁻¹ dw in soil and 0.22–0.51 ng g⁻¹ dw in manure. The deuterated analog of toltrazuril was used as internal standard, and ensured method accuracy in the range 96–123% for water and 77–110% for soil samples. The developed method can also be applied to simultaneously determine steroid hormones in the solid samples. The antiparasitic drug and its metabolites were found in manure and soil up to 114 and 335 pg g⁻¹ dw, respectively. Little is known regarding the environmental fate and effects of these compounds; consequently more research is urgently needed.     

Determination of aflatoxins in cereal flours by solid-phase microextraction coupled with liquid chromatography and post-column photochemical derivatization-fluorescence detection

A new method for the determination of aflatoxins B₁, B₂, G₁, and G₂ (AFB₁, AFB₂, AFG₁, AFG₂) in cereal flours based on solid-phase microextraction (SPME) coupled with high performance liquid chromatography with post-column photochemical derivatization and fluorescence detection (SPME–HPLC–PD–FD) has been developed. Aflatoxins were extracted from cereal flour samples by a methanol:phosphate buffer (pH 5.8, I = 0.1) (80:20, v/v) solution, followed by a SPME step. Different SPME and HPLC–PD–FD parameters (fiber polarity, temperature, pH, ionic strength, adsorption and desorption time, mobile phase) have been investigated and optimized. This method, which was assessed for the analysis of different cereal flours, showed interesting results in terms of LOD (from 0.035 to 0.2 ng g⁻¹), LOQ (from 0.1 to 0.63 ng g⁻¹, respectively), within and inter-day repeatability (2.27% and 5.38%, respectively) linear ranges (up to 20 ng g⁻¹ for AFB₁ and AFG₁ and 6 ng g⁻¹ for AFB₂ and AFG₂), and total raw extraction efficiency (in the range 55–59% at concentrations in the range 0.3–1 ng g⁻¹ and 49–52% at concentrations in the range 1–10 ng g⁻¹). The results were also compared with the purification step carried out by conventional immunoaffinity columns.     

A highly sensitive and selective immunoassay for the detection of tetrabromobisphenol A in soil and sediment

Tetrabromobisphenol A is the most widely used brominated flame retardant. A sensitive and selective enzyme-linked immunosorbent assay (ELISA) for the detection of tetrabromobisphenol A was developed. The limit of detection and the inhibition half-maximum concentration of tetrabromobisphenol A in phosphate buffered saline with 10% methanol were 0.05 and 0.87 ng mL⁻¹, respectively. Cross-reactivity values of the ELISA with a set of important brominated flame retardants including tetrabromobisphenol A-bis(2,3-dibromopropylether), 2,2′,6,6′-tetrabromobisphenol A diallyl ether, hexabromocyclododecane, 1,2-bis(pentabromodiphenyl) ethane, 1,2-bis(2,4,6 tribromophenoxy) ethane, bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate, 2-ethylhexyl-2,3,4,5-tetrabromobenzoate, and polybrominated diphenyl ethers were <0.05%. Concentrations of tetrabromobisphenol A determined by ELISA in the soils from farmlands, the soils from an e-waste recycling site, and the sediments of a canal were in the range of non-detectable–5.6 ng g⁻¹, 26–104 ng g⁻¹ and 0.3–22 ng g⁻¹ dw, respectively, indicating the ubiquitous pollution of tetrabromobisphenol A. The results of this assay for 16 real world samples agreed well with those of the liquid chromatography–tandem mass spectrometry method, indicating this ELISA is suitable for screening of tetrabromobisphenol A in environmental matrices.     

Pressurised membrane-assisted liquid extraction of UV filters from sludge

A method for the determination of 11 UV-filter compounds in sludge has been developed and evaluated. The procedure includes the use of non-porous polymeric membranes in combination with pressurised liquid extraction (PLE). Firstly, the solid sample, wetted with the extraction solvent, was enclosed into tailor-made bags prepared with low density polyethylene. Secondly, these packages were submitted to a conventional PLE (70 °C, 4 cycles of 5 min static time). Finally, the analytes were determined by liquid chromatography–atmospheric pressure photoionisation–tandem mass spectrometry. The main advantage of this procedure is the reduction of time, solvent and labour effort ought to the combination of extraction and clean-up in a single step. Although the extraction is not quantitative (thus, standard addition is recommended for quantification) selectivity is clearly gained using the membrane as a consequence of the differences of permeation and transport through the membrane between the analytes and other sample matrix components. The optimised protocol provides limits of detection ranging from 0.3 ng g⁻¹ (ethylhexyl dimethyl p-aminobenzoate (OD-PABA)) to 25 ng g⁻¹ (ethylhexyl triazone (EHT)) with only 0.5 g of sludge sample. All the studied UV filters were found in the samples at concentration levels between 1.4 and 2479 ng g⁻¹, emphasising the high adsorption potential of this kind of environmental pollutants onto solid samples such as sludge. Also, this method has permitted the determination of seven of the studied UV filters in sludge samples for the first time.     

Determination of carbamate pesticides using micro-solid-phase extraction combined with high-performance liquid chromatography

We describe a simple and sensitive porous polypropylene membrane-protected micro-solid-phase extraction (μ-SPE) approach for the sample preparation and determination of carbamate pesticides in soil samples by high-performance liquid chromatography. The μ-SPE device consisted of C₁₈ sorbent held within a porous polypropylene envelope. In order to achieve optimum performance, several extraction parameters were optimized. Under the most favorable conditions, the extraction efficiency of the μ-SPE was very high, with detection limits in the range of 0.01–0.40 ng g⁻¹. This is more than two orders of magnitude lower than the limits obtained by the United States Environmental Protection Agency Methods 8321A and 8318. A linear relationship was obtained for each analyte in the range of 2 and 200 ng g⁻¹. The relative standard deviation for the analysis of aged soil samples spiked at 5 ng g⁻¹ was ≤11%. The reproducibility of separate μ-SPE device used for experiments was satisfactory (relative standard deviations ranged from 4 to 11%), indicating that the method is reliable for routine environmental analysis.     

Development and validation of ultra-high performance supercritical fluid chromatography method for determination of illegal dyes and comparison to ultra-high performance liquid chromatography method

A novel simple, fast and efficient ultra-high performance supercritical fluid chromatography (UHPSFC) method was developed and validated for the separation and quantitative determination of eleven illegal dyes in chili-containing spices. The method involved a simple ultrasound-assisted liquid extraction of illegal compounds with tetrahydrofuran. The separation was performed using a supercritical fluid chromatography system and CSH Fluoro-Phenyl stationary phase at 70 °C. The mobile phase was carbon dioxide and the mixture of methanol:acetonitrile (1:1, v/v) with 2.5% formic acid as an additive at the flow rate 2.0 mL min⁻¹. The UV–vis detection was accomplished at 500 nm for seven compounds and at 420 nm for Sudan Orange G, Butter Yellow, Fast Garnet GBC and Methyl Red due to their maximum of absorbance. All eleven compounds were separated in less than 5 min. The method was successfully validated and applied using three commercial samples of chili-containing spices – Chili sauce (Indonesia), Feferony sauce (Slovakia) and Mojo sauce (Spain). The linearity range of proposed method was 0.50–9.09 mg kg⁻¹ (r ≥ 0.995). The detection limits were determined as signal to noise ratio of 3 and were ranged from 0.15 mg kg⁻¹ to 0.60 mg kg⁻¹ (1.80 mg kg⁻¹ for Fast Garnet) for standard solution and from 0.25 mg kg⁻¹ to 1.00 mg kg⁻¹ (2.50 mg kg⁻¹ for Fast Garnet, 1.50 mg kg⁻¹ for Sudan Red 7B) for chili-containing samples. The recovery values were in the range of 73.5–107.2% and relative standard deviation ranging from 0.1% to 8.2% for within-day precision and from 0.5% to 8.8% for between-day precision. The method showed potential for being used to monitor forbidden dyes in food constituents. The developed UHPSFC method was compared to the UHPLC-UV method. The orthogonality of Sudan dyes separation by these two methods was demonstrated. Benefits and drawbacks were discussed showing the reliability of both methods for monitoring of studied illegal dyes in real food constituents.     

Coacervative microextraction ultrasound-assisted back-extraction technique for determination of organophosphates pesticides in honey samples by gas chromatography–mass spectrometry

Coacervative microextraction ultrasound-assisted back-extraction technique (CME-UABE) is proposed for the first time for extracting and preconcentrating organophosphates pesticides (OPPs) from honey samples prior to gas chromatography–mass spectrometry (GC–MS) analysis. The extraction/preconcentration technique is supported on the micellar organized medium based on non-ionic surfactant. To enable coupling the proposed technique with GC, it was required to back extract the analytes into hexane. Several variables including, surfactant type and concentration, equilibration temperature and time, matrix modifiers, pH and buffers nature were studied and optimized over the relative response of the analytes. The best working conditions were as follows: an aliquot of 10 mL 50 g L⁻¹ honey blend solution was conditioned by adding 100 μL 0.1 mol L⁻¹ hydrochloric acid (pH 2) and finally extracted with 100 μL Triton X-114 100 g L⁻¹ at 85 °C for 5 min using CME technique. Under optimal experimental conditions, the enrichment factor (EF) was 167 and limits of detection (LODs), calculated as three times the signal-to-noise ratio (S/N = 3), ranged between 0.03 and 0.47 ng g⁻¹. The method precision was evaluated over five replicates at 1 ng g⁻¹ with RSDs ≤9.5%. The calibration graphs were linear within the concentration range of 0.3–1000 ng g⁻¹ for chlorpirifos; and 1–1000 ng g⁻¹ for fenitrothion, parathion and methidathion, respectively. The coefficients of correlation were ≥0.9992. Validation of the methodology was performed by standard addition method at two concentration levels (2 and 20 ng g⁻¹). The recoveries were ≥90%, indicating satisfactory robustness of the methodology, which could be successfully applied for determination of OPPs in honey samples of different Argentinean regions. Two of the analyzed samples showed levels of methidathion ranged between 1.2 and 2.3 ng g⁻¹.     

Determination of cyromazine and melamine in chicken eggs using quick,easy, cheap,effective, rugged and safe (QuEChERS) extraction coupled with liquid chromatography–tandem mass spectrometry

A rapid and sensitive method has been developed for the simultaneous detection of cyromazine and melamine in chicken eggs using the quick, easy, cheap, effective, rugged and safe (QuEChERS) method coupled with liquid chromatography–tandem mass spectrometry (LC–MS/MS). The optimal extraction solvent for the liquid–liquid extraction was 5 mL of acetonitrile with a 0.1 M hydrochloric acid aqueous solution (99.5:0.5, v/v). The extract was cleaned with 0.5 g of anhydrous magnesium sulfate and 10 mg of graphitized carbon black. The analysis of cyromazine and melamine was accomplished by combining the use of an anion exchange LC column with tandem mass spectrometry in the positive electrospray ionization mode with selected reaction monitoring mode (SRM). The detection limits were 1.6 ng g⁻¹ for cyromazine and 8 ng g⁻¹ for melamine, and the quantitation limits were 5.5 ng g⁻¹ for cyromazine and 25 ng g⁻¹ for melamine. The recoveries of cyromazine and melamine in the spiked egg samples were 83.2% and 104.6%, respectively, with an relative standard deviation (RSD) of less than 18.1%. The intra-day and inter-day precisions, represented by the RSD, ranged from 1.5% to 8.8% and 6.8% to 14.3%, respectively. The proposed method was tested by analyzing chicken eggs from the markets and from the veterinary medicine laboratory. The concentrations of cyromazine and melamine detected in these samples were in the range of 20–94 ng g⁻¹. The results demonstrated that the QuEChERS method combined with LC–MS/MS is a simple, rapid and inexpensive method for the analysis of cyromazine and melamine in eggs.     

Development of hyperbranched polymers with non-covalent interactions for extraction and determination of aflatoxins in cereal samples

A novel approach for assembling homogeneous hyperbranched polymers based on non-covalent interactions with aflatoxins was developed; the polymers were used to evaluate the extraction of aflatoxins B1, B2, G1 and G2 (AFB1, AFB2, AFG1 and AFG2) in simulant solutions. The results showed that the extraction efficiencies of three kinds of synthesized polymers for the investigated analytes were not statistically different; as a consequence, one of the representative polymers (polymer I) was used as the solid-phase extraction (SPE) sorbent to evaluate the influences of various parameters, such as desorption conditions, pH, ionic strength, concentration of methanol in sample solutions, and the mass of the sorbent on the extraction efficiency. In addition, the extraction efficiencies for these aflatoxins were compared between the investigated polymer and the traditional sorbent C18. The results showed that the investigated polymer had superior extraction efficiencies. Subsequently, the proposed polymer for the SPE packing material was employed to enrich and analyze four aflatoxins in the cereal powder samples. The limits of detection (LODs) at a signal-to-noise (S/N) ratio of 3 were in the range of 0.012–0.120 ng g⁻¹ for four aflatoxins, and the limits of quantification (LOQs) calculated at S/N = 10 were from 0.04 to 0.40 ng g⁻¹ for four aflatoxins. The recoveries of four aflatoxins from cereal powder samples were in the range of 82.7–103% with relative standard deviations (RSDs) lower than 10%. The results demonstrate the suitability of the SPE approach for the analysis of trace aflatoxins in cereal powder samples.     

Multi-analyte method for the analysis of various organohalogen compounds in house dust

In the present study, a novel analytical approach for the simultaneous determination of 27 brominated flame retardants (BFRs), namely polybrominated diphenyl ethers (PBDEs), isomers of hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBPA) and several novel BFRs (NBFRs), together with 18 perfluoroalkyl substances (PFASs) in indoor dust was developed and validated. To achieve integrated isolation of analytes from the sample and their fractionation, a miniaturized method based on matrix solid phase dispersion (MSPD) was employed. Principally, after mixing the dust (<0.1 g) with the Florisil^®, the mixture was applied on the top of a sorbent (Florisil^®) placed in glass column and then analytes were eluted using solvents with different polarities. For the identification/quantification of target compounds largely differing in polarity, complementary techniques represented by gas and liquid chromatography coupled to tandem mass spectrometry (GC–MS/MS and LC–MS/MS) were used. The results of validation experiments, which were performed on the SRM 2585 material (for PBDEs, HBCDs and TBBPA), were in accordance with the certified/reference values. For other analytes (NBFRs and PFASs), the analysis of an artificially contaminated blank dust sample was realized. The method recoveries for all target compounds ranged from 81 to 122% with relative standard deviations lower than 21%. The quantification limits were in the range of 1–25 ng g⁻¹ for BFRs and 0.25–1 ng g⁻¹ for PFASs. Finally, 18 samples (6 households × 3 sampling sites) were analyzed. The high variability between concentrations of PFASs and BFRs in the dust samples from various households as well as collecting sites in a respective house was observed. The total amounts of PFASs and BFRs were in the range of 1.58–236 ng g⁻¹ (median 10.6 ng g⁻¹) and 39.2–2320 ng g⁻¹ (median 325 ng g⁻¹), respectively. It was clearly shown that dust from the indoor environment might be a significant source of human exposure to various organohalogen pollutants.