Method Quantitation Limits Research Articles

Understanding of resilience in the context of regional development using composite index approach: the case of European Union NUTS-2 regions

ABSTRACTEconomies have always been prone to different kinds of exogenous shocks, which can destabilize the path and pattern of regional economic growth. Regional economy perturbed by a shock may move onto a new growth path by re-establishing economic linkages, both internally and with other regions. The question why one region is more vulnerable to economic shock than other, impelled to analyze notion of resilience in a regional development context. Despite own limitations of quantitative methods, several approaches in the form of composite indices (CIs) have been proposed by the European Union (EU) and the other institutions. The aim of this paper is to throw light on some of the underlying aspects of regional resilience and provide an overview of a notion as well as analysis of research studies on constructing the territorial CIs. The main results of the paper are overview and comparison of regional resilience literature and empirics of existing CIs that lead to measuring the EU NUTS-2 regions resilience based on constructing own index. CIs construction includes several steps that have to be made and corresponding methods have to be chosen. Primarily, selection of sub-indicators, normalizing methods, weighting schemes and aggregation formulas are fundamental.

Simultaneous Determination of Aflatoxin B1, Bisphenol A, and 4-Nonylphenol in Peanut Oils by Liquid-Liquid Extraction Combined with Solid-Phase Extraction and Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

An analytical method based on liquid-liquid extraction combined with solid-phase extraction and isotope dilution-ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was well developed for simultaneous determination of aflatoxin B1 (AFB1), bisphenol A (BPA), and 4-nonylphenol (4-NP) in peanut oil. After adding isotope internal standards, the samples were firstly diluted by normal hexane and then extracted by acetonitrile and Carb/PSA solid-phase extraction cartridge in sequence to obtain the extracted solution. All the extracted solution was merged and was subsequently dried to near dryness by a mild nitrogen stream. Three target analytes were separated on a Phenomenex Luna C18 chromatographic column, quantified by an internal standard method and detected by ESI positive (ESI+) and negative (ESI−) subsection acquisition modes under multi-reaction monitoring (MRM) conditions. Results demonstrated that the three target analytes exhibited excellent linearity in their corresponding concentration ranges of 0.1–100.0 μg/L with correlation coefficients all greater than 0.998. The corresponding method limits of quantitation (MLOQ, S/N = 10) of AFB1, BPA, and 4-NP were 0.2, 1.0, and 2.0 μg/kg, respectively. Moreover, the mean recoveries for negative samples spiked at three concentration levels were calculated between 87.7 and 105.1% with relative standard deviation (RSD, n = 6) ranging from 2.2 to 7.9% and the interday precision (n = 5) ranging from 5.0 to 8.7%. Finally, the method was successfully applied to analyze 52 peanut oil samples, and AFB1 and 4-NP were detected in 43 samples with the concentrations in the ranges of 0.5–69.4 and 9.3–77.8 μg/kg, respectively. None of BPA was detected in any samples.

Validation protocol for whole-body dosimetry in an agricultural exposure study

Agricultural workers exposed to pesticides can experience adverse health impacts depending on toxicity and exposure amount. Whole-body dosimetry (WBD) is the most reliable, practical, and realistic method for measuring exposure. Since validation of analytical and experimental methodologies is critical for quantitative determination of exposure, we conducted a validation procedure to design an essential protocol for WBD exposure studies. Using the fungicide kresoxim-methyl, matrix-matched standards were prepared with various matrices including outer cloth, inner cloth, washing solution for gloves and hands, gauze, and glass fiber filter (IOM sampler) to determine the instrumental limit of quantitation for high-performance liquid chromatography (HPLC) (2 ng) and liquid chromatography–tandem mass spectrometry (LC–MS/MS) (10 pg). Method limits of quantitation (MLOQ) were also set for HPLC (0.1 mg/L) and LC–MS/MS (0.005 mg/L). We observed good analysis repeatability (coefficient of variation < 6%), and the linearity of the calibration curves was reasonable (r 2 > 0.998) in the range of 0.001–10 mg/L in various matrices. Recovery tests were carried out at three levels of concentration (MLOQ, 10 MLOQ, and 100 MLOQ) and resulted in good recoveries (72.7–105.6%). We did not observe breakthrough of the compound in tests of holding capacity for glass fiber pesticide filters. The procedures established in the present study are applicable as an essential, comprehensive protocol for exposure assessment studies using WBD.

Occurrence of phthalate diesters in indoor air from several Northern cities in Vietnam, and its implication for human exposure

Phthalates are used as plasticizers to impart flexibility of plastics. Because of their toxicity, human exposure to phthalates is a concern. Little is known on the occurrence of and inhalation exposure to phthalates in indoor air. In this study, ten phthalates were measured in 97 indoor air samples collected from Northern Vietnam during September 2016 to January 2017. The mean concentrations of total phthalates (i.e., sum of ten phthalates) in particulate and gas phases ranged from 95.2 to 13,100μgg−1 and from 57.0 to 14,900ngm−3, respectively. In bulk indoor air samples (i.e., gas plus particulate phase), the mean concentration of total phthalates ranged from 106 to 16,000ngm−3 (mean: 1040ngm−3). Diethyl phthalate (DEP) was found at the highest concentration in indoor air at a concentration range of below the method quantitation limit (MQL) to 12,400ngm−3 (mean: 376). Among various microenvironments, indoor air collected from hair salons contained the highest concentrations of phthalates (range: 596 to 16,000ngm−3). Among the four northern Vietnamese cities studied, the highest concentrations of phthalates were found in indoor air samples from Hanoi. The calculated mean inhalation exposure doses to phthalates for infants, toddlers, children, teenagers, and adults were 780, 485, 416, 292, and 213ngkg-bw−1d−1, respectively.

Poly(glycidyl methacrylate) nanoparticle-coated capillary with oriented antibody immobilization for immunoaffinity in-tube solid phase microextraction: Preparation and characterization

A combination between modification with nanoparticles (NP) and oriented antibody immobilization (OAI) on the inner face of capillary was for the first time developed for immunoaffinity in-tube solid-phase microextraction (SPME) to promise high antigen extraction capacity. β2-microglobin (β2MG) and cystatin C (Cys-C) were selected as model antigens. Poly(glycidyl methacrylate) (PGMA) NPs were chemically immobilized onto the capillary by a ring-opening reaction. Antibodies for β2MG and Cys-C were immobilized on the NPs through OAI. Scanning electron micrograph of the OAI capillary clearly showed that the PGMA NPs were coated onto the inner surface of capillary in a dense monolayer. In addition, random antibody immobilized (RAI) capillaries and OAI capillaries without NP were also prepared as controls. The extraction capacities of OAI capillaries were 2.02 and 2.18mgm−1 for β2MG and Cys-C, and were about 5 and 6 times as many as RAI capillaries and OAI capillaries without NP, respectively. The resultant capillaries were used as in-tube SPME materials to enrich β2MG and Cys-C for particle-enhanced turbidimetric immunoassay. When using 1.0mgL−1 standard solutions, the recoveries of OAI capillaries, RAI capillaries and OAI capillaries without NP were 103.6% and 96.8%, 48.5% and 31.5%, and 24.2% and 25.7% for β2MG and Cys-C, respectively. Furthermore, the method quantitation limit by OAI capillaries was 5 and 10 times lower than that by RAI capillaries and OAI capillaries without NP, respectively. This result indicated that the NP-coated capillaries with OAI are more suitable for using as immunoaffinity in-tube SPME materials than that with RAI.

A new sample preparation method for crude or fuel oils by mineralization utilizing single reaction chamber microwave for broader multi-element analysis by ICP techniques

The objective of this study was to develop an effective and routine single sample preparation method to accurately and precisely analyze multiple elements (up to 57) in crude oils using both an inductively coupled plasma-optical emission spectrometer (ICP-OES) for high abundance elements and a triple quadrupole-inductively coupled plasma-mass spectrometer (QQQ-ICP-MS) (or ICP-MS) for low abundance trace and ultra-trace elements. A critical aspect of this study was to develop a single sample preparation method that could be effective in analyzing the largest number of quantifiable elements with instruments used in tandem to cover a wider and more practical combined dynamic range. Three sample preparation techniques were investigated and tested, including high pressure combustion with strong-acid digestion, high pressure and high temperature strong-acid digestion within Parr bombs, and high temperature and high pressure digestions in a Single Reaction Chamber (SRC) microwave. For the combustion method, no element showed recovery above 75%, thus this method was deemed unacceptable for accurate and precise analysis of crude oil. Average recoveries ranging from 94% to 106% for 19 analytes were achieved with high pressure and high temperature acid digestion within Parr bombs. A drawback of the method, however, was a rather small sample sizes (100mg) that could be achieved without venting, which places limitations on detection and quantitation limits of large numbers of low abundance analytes in natural crude oils. The best of the SRC microwave-assisted acid digestion tests, however, was also shown to be acceptable for 19 analytes using a certified organometallic standard, with average recoveries ranging from 93% to 113%. Because of rapid sample throughput and the larger sample sizes (1.2g sample size per digestion session) that can be accommodated with the single reaction chamber microwave digestion technique, better method detection and quantification limits and high precision on a range of low abundance elements could be achieved. We also then successfully tested the recovery of 53 elements with this SRC microwave method by adding a multi-element spike to Conostan base oil. This optimum SRC digestion method tested was then used to examine a NIST natural crude oil research material (NIST RM 8505) in an attempt to quantify up to 57 elements. The mean vanadium concentration (mass fraction) is reported as 390±0.4µg/g, the mean value of 5 replicate digestions by our method, which agrees well with the recommended value for the only element recommended for NIST 8505 of 390±10µg/g. The number of quantified analytes for the RM 8505 was further extended to a total of 52 elements with RSDs <5% for 38 elements, between 5% and 10% for 10 elements, and between 10% and 15.6% for 4 elements, all of which met our acceptability limits set at ≤20% RSD. Of the 57 elements analyzed in RM 8505, certain elements B, Nb, and W, although above method quantitation limits, were judged unacceptable because RSDs were ≥31.4%, whereas Ag and Tl were below method quantitation limits, and their RSDs were ≥44.2% and judged unacceptable. However, these elements have been quantified in other natural crude oils with higher abundances, which indicates that up to 57 elements can be potentially assessed in crude oils or refined oils with this method. The NIST RM 8505 crude oil reported here and others are being evaluated as potential natural crude oil standards to provide references values for more routine multi-element analysis.

Gas Chromatography-Mass Spectrometry Method to Quantify Benzo[a]Pyrene in Tobacco Products.

The USA Food and Drug Administration (FDA) established benzo[a]pyrene (B[a]P) as a harmful and potentially harmful constituent (HPHC) found in tobacco products. Tobacco manufacturers are required to report HPHC quantities to the FDA; however, there is currently no standardized method for determination of B[a]P in smokeless tobacco products (STPs). This work details a sensitive, selective and rapid method for the determination of B[a]P in STPs, cigarette filler and tobacco. Tobacco is extracted using methanol followed by solid-phase extraction and concentration prior to analysis by gas chromatography/mass spectrometry in the selected ion monitoring mode. Cooperation Centre for Scientific Research Relative to Tobacco reference products and 3R4F Kentucky reference cigarette filler were used for method validation. All method validation requirements were met including linearity, accuracy, precision, robustness, limit of detection (LOD) and limit of quantitation (LOQ), and stability. Calibration range of 0.5-125 ng mL-1 was achieved with the coefficient of determination (R2) greater than 0.995. The method LOQ and LOD were 0.729 and 0.216 ng/g, respectively. Using standardized methods for the measurement of HPHCs in tobacco products will reduce variability and ensure accurate data for regulatory reporting.

Simultaneous determination of eight alkaloids and oleandrin in herbal cosmetics by dispersive solid-phase extraction coupled with ultra high performance liquid chromatography and tandem mass spectrometry.

We utilized ultra-high performance liquid chromatography with tandem mass spectrometry and dispersive solid-phase extraction to develop a new method for the detection of nine analytes (scopolamine, cephaeline, strychnine, hyoscyamine, brucine, hydrastine, ajmalicine, colchicine, and oleandrin) in herbal cosmetics. Acetonitrile/water and 2-propylaminoethylamine were used to disperse and purify during the dispersive solid-phase extraction step. The analytes were separated by a Waters UPLC HSS T3 column and detected through electrospray ionization source in the positive mode with multi-reaction monitoring conditions. Under the optimal conditions, the calibration curves were linear in the range of 0.2-100.0μg/L with the correlation coefficients higher than 0.995. The method limit of quantitation (S/N=10) were 5.0μg/kg for oleandrin and 1.0μg/kg for the other eight alkaloids. The mean recoveries at three spiked concentration levels of 1.0-10.0μg/kg were in the range of 86.9-116.5% with the intra-day relative standard deviations (n=6) ranging from 2.4 to 8.8%, and inter-day relative standard deviations ranging from 2.7 to 5.7%. This method is accurate, simple and rapid, and has been applied to the quality supervision of herbal cosmetics in Guangzhou.

Development of a Residue Analysis Method for Metamifop in Paddy Water, Soil, and Rice with HPLC

An analytical method for detecting metamifop residue in paddy water, soil, and rice with high performance liquid chromatography (HPLC) was developed. Water was extracted with ethyl acetate before analyzing by HPLC. Soil residues were extracted with acetone under acidic condition and after purifying with Extrelut ® NT, and silica SPE, the residue was analyzed by HPLC. For residue analysis in rice, the procedure involved extraction with acetone, purification with Extrelut ® NT, partitioning between acetonitrile/hexane, purification with silica SPE cartridge, and analysis by HPLC. The limit of detection (LOD) was 1.0 ng, limit of quantitation (LOQ) was 3.0 ng, and method limit of quantitation (MLOQ) were 0.001 mg/L for paddy water, 0.01 mg/kg for rice and soil, respectively. Standard calibration curve shows linearity from 0.05 mg/kg to 5.0 mg/kg (R 2 = 0.9999). The recoveries in fortified paddy water were 91.3 ± 3.5% (0.01 mg/L level) and 93.2 ± 6.3% (0.05 mg/L level). The recoveries in fortified paddy soils were 92.5 ± 4.0% (0.1 mg/kg level) and 92.7 ± 4.0% (0.5 mg/kg level) in soil A, while, 102.3 ± 4.4% (0.1 mg/kg level) and 98.9 ± 7.9% (0.5 mg/kg level) in soil B, respectively. The recoveries in fortified rice were 93.0 ± 6.9% (0.1 mg/kg level) and 85.0 ± 3.5% (0.5 mg/kg level). This method was proved to be effective and can be used to determine the metamifop residue in paddy water, paddy soil, and rice.

Modified QuEChERS combined with ultra high performance liquid chromatography tandem mass spectrometry to determine seven biogenic amines in Chinese traditional condiment soy sauce

A rapid and sensitive UHPLC-MS/MS method followed by modified QuEChERS was developed for the simultaneous determination of seven biogenic amines in soy sauce. Samples were firstly diluted by water and pH values of which were adjusted using ammonia water. Modified QuEChERS method was adopted for the purification and 1, 7-heptyldiamine was used as the internal standard. Analysis of seven biogenic amines was within 4min. Under the optimized conditions, linear relations were favorable over the selected concentration ranges of 3.0-600μg/L with correlationcoefficients greater than 0.999. The average accuracy was between 84% and 115%. Intra- and inter- assay precisions for six replicates ranged from 2.2% to 8.8% or below 12%, respectively. The method limits of detection and the method limits of quantitation were 4-8μg/kg and 15-30μg/kg, respectively. The method was successfully applied to determine the concentrations of seven biogenic amines in soy sauces.

Determination of 4-n-octylphenol, 4-n-nonylphenol and bisphenol A in fish samples from lake and rivers within Hunan Province, China

The presence of endocrine disrupting chemicals such as 4-n-octylphenol, 4-n-nonylphenol and bisphenol A in environmental samples and artificial products may cause health problems for human and organisms. This developed method was efficient for monitoring of those tracing emerging contaminates and the Plackett-Burman factorial design introduced in extraction step was timesaving. Matrix effect was also considered to ensure proper quantitation. Good linearity (r2>0.99), low Method Detection Limits (MDL) and Method Quantitation Limits (MQL) range from 0.18 to 0.54ng/g and 0.60 to 1.80ng/g were obtained. Three level spiking experiment (4, 10, 15ng/g) showed recoveries range from 74% to 113% for 4-n-octylphenol and 4-n-nonylphenol with RSD range from 2% to 11%. The method was finally applied to the analysis of real fish samples taken from Hunan Province, China, offering a reliable and effective means for monitoring of trace emerging contaminates in fishes largely consumed by residents.

Multi-residue determination of micropollutants in Phragmites australis from constructed wetlands using microwave assisted extraction and ultra-high-performance liquid chromatography tandem mass spectrometry

In constructed wetlands micropollutants can be removed from water by phytoremediation. However, micropollutant uptake and metabolism by plants here is poorly understood due to the lack of good analytical approaches. Reported herein is the first methodology developed and validated for the multi-residue determination of 81 micropollutants (pharmaceuticals, personal care products and illicit drugs) in the emergent macrophyte Phragmites australis. The method involved extraction by microwave accelerated extraction (MAE), clean-up using off-line solid phase extraction and analysis by ultra-high-performance liquid chromatography tandem mass spectrometry. Development of the MAE method found the influence of studied variables on micropollutant recovery to be: extraction temperature > sample mass > solvent composition. Validation of the developed extraction protocol revealed method recoveries were in the range 80–120% for the majority of micropollutants. Method quantitation limits (MQLs) were generally <5 ng g−1 dry weight demonstrating the sensitivity of the methodology. Application of the method to P. australis from a constructed wetland used to treat trickling filter effluent found 17 micropollutants above their MQL, up to concentrations of 200 ng g−1. Other than uptake, the presence of several metabolites (carbamazepine 10,11 epoxide, desvenlafaxine, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine, N-desmethyltramadol and norketamine) indicated metabolism within the plant may also occur. This new analytical methodology will enable a process mass balance of the constructed wetland to be attained for the first time, and thus help understand the role of phytoremediation in micropollutant removal by such systems.

New Spectrophotometric Method for the Assay of Sulfadiazine Drug Based on Diazotization Coupling Reaction

Abstract A sensitive, simple and rapid spectrophotometric procedure for the assay of trace quantities of sulfadiazine (SDZ) drug as bulk and in diluted solution is characterized. The procedure depends on the diazotization reaction which is produced by coupling SDZ with (4-amino-2-hydroxy acetophenon) (AHA) to produce an intense colored complex spectrophotometrically determined at 410 nm. Beer’s law was applied in the range of concentration 0.5 - 15 ppm; the molar absorptivity and Sandell’s sensitivity were 2.8484 × 104 L mol-1 cm-1 and 0.008 μg cm-2 respectively. The method limit of detection (LOD) was 0.443 μg mL-1 and LOQ (the method limit of quantitation) was 0.249 μg mL-1. The procedure is not based on solvent extraction and the additives and excipients do not significantly influence the developed procedure.

Simultaneous determination of seven multiclass veterinary antibiotics in surface water samples in the Republic of Korea using liquid chromatography with tandem mass spectrometry

A simultaneous determination method using solid-phase extraction and liquid chromatography with tandem mass spectrometry was developed to detect and quantify the presence of seven multiclass veterinary antibiotics (13 compounds in total) in surface water samples, which included the effluents of livestock wastewater and sewage treatment plants, as well as the reservoir drainage areas from dense animal farms. The pH of all water samples was adjusted to 2 or 6 before solid-phase extraction using Oasis HLB cartridges. The developed method was fully validated in terms of linearity, method detection limit, method quantitation limit, accuracy, and precision. The linearity of all tested drugs was good, with R2 determination coefficients ≥ 0.9931. The method detection limits and method quantitation limits were 0.1-74.3 and 0.5-236.6ng/L, respectively. Accuracy and precision values were 71-120 and 1-17%, respectively. The determination method was successfully applied for monitoring water samples obtained from the Yeongsan River in 2015. The most frequently detected antibiotics were lincomycin (96%), sulfamethazine (90%), sulfamethoxazole (88%), and sulfathiazole (50%); the maximum concentrations of which were 398.9, 1151.3, 533.1, and 307.4ng/L, respectively. Overall, the greatest numbers and concentrations of detected antibiotics were found in samples from the effluents of livestock wastewater, sewage treatment plants, and reservoir drainage areas. Diverse veterinary antibiotics were present, and their presence was dependent upon the commercial sales and environmental properties of the analytes, the geographical positions of the sampling points, and the origin of the water.

Relationship between atmospheric pollution in the residential area and concentrations of polycyclic aromatic hydrocarbons (PAHs) in human breast milk

Human milk is an important source of beneficial nutrients and antibodies for newborns and infants and, under certain circumstances, its analysis may provide information on mothers' and infants' exposure to various contaminants. In the presented study, we have introduced the new analytical approach for analysis of 24 highly occurring polycyclic aromatic hydrocarbons (PAHs) in this indicator matrix. The sample preparation procedure is based on an ethyl acetate extraction of milk; the transfer of analytes into an organic layer is enhanced by addition of inorganic salts, i.e. sodium chloride and magnesium sulphate. Following the clean-up of a crude extract on silica SPE columns, gas chromatography coupled to triple quadrupole mass spectrometry is used for PAH identification and quantitation. The average recoveries of targeted PAHs from spiked samples were in the range of 68–110% with repeatabilities below 30% and method quantitation limits ranging from 0.03 to 0.3ng/g lipid weight. This newly validated method was successfully applied for analyses of 324 human milk samples collected from nonsmoking women during two sampling periods (summer and winter) in two residential areas in the Czech Republic differing in atmospheric pollution by PAHs. From 24 targeted analytes 17 were detected at least in one sample. Phenantherene, fluoranthrene, pyrene and fluorene were the most abundant compounds found at average concentration of 13.81, 1.80, 0.86, and 2.01ng/g lipid weight respectively. Comparing the data from two sampling periods, in both areas higher concentrations were measured in samples collected during winter. Also in the highly industrialized locality with heavily contaminated air PAH amounts in milk were higher than in the control locality. These first data on PAH concentrations in human milk collected in the Czech Republic are comparable with measurements for nonsmoking women reported earlier in the United States but significantly lower than results from China, Turkey or Italy.

Multi-residue analysis of 90 emerging contaminants in liquid and solid environmental matrices by ultra-high-performance liquid chromatography tandem mass spectrometry

Reported herein is new analytical methodology for the determination of 90 emerging contaminants (ECs) in liquid environmental matrices (crude wastewater, final effluent and river water). The application of a novel buffer, ammonium fluoride improved signal response for several ECs determined in negative ionisation mode. Most notably the sensitivity of steroid estrogens was improved by 4–5 times in environmental extracts. Method recoveries ranged from 40 to 152% in all matrices and method quantitation limits (MQLs) achieved were <1ngL−1 for numerous ECs. Development of a microwave assisted extraction (MAE) protocol as an additional sample extraction step for solid matrices enabled 63 ECs to be simultaneously analysed in digested sludge. To the authors knowledge this is considerably more than any previously reported MAE method. Here, MQLs ranged from 0.1–24.1ngg−1 dry weight. The application of MAE offers several advantages over pressurized liquid extraction including faster sample preparation, lower solvent requirements, and the ability to perform several extractions simultaneously as well as lower purchasing and running costs. To demonstrate the method’s sensitivity, application to environmental samples revealed 68 and 40 ECs to be above their respective MQL in liquid environmental samples and digested sludge, respectively. To date, this is the most comprehensive multi-residue analytical method reported in the literature for the determination of ECs in both liquid and solid environmental matrices.

Analytical capabilities of high performance liquid chromatography – Atmospheric pressure photoionization – Orbitrap mass spectrometry (HPLC-APPI-Orbitrap-MS) for the trace determination of novel and emerging flame retardants in fish

A new analytical method was established and validated for the analysis of 27 brominated flame retardants (BFRs), including so called “emerging” and “novel” BFRs (EBFRs and NBFRs) in fish samples. High performance liquid chromatography (HPLC) coupled to Orbitrap mass spectrometry (Orbitrap-MS) employing atmospheric pressure photoionization (APPI) interface operated in negative mode was used for the identification/quantitation of contaminants. HPLC-Orbitrap-MS analysis provided a fast separation of selected analytes within 14 min, thus demonstrating a high throughput processing of samples. The developed methodology was tested by intralaboratory validation in terms of recovery, repeatability, linear calibration ranges, instrumental and method limits of quantitation (i-LOQ and m-LOQ), and where possible, trueness was verified by analysis of certified reference materials (CRMs). Recoveries of analytes were between 80 and 119%, while the repeatability in terms of relative standard deviations (RSDs) was in the range from 1.2 to 15.5%. The measured values for both analyzed CRMs agreed with the provided consensus values, revealing the recovery of reference concentrations in 72–119% range. The elaborated method met the sensitivity criterion according to Commission Recommendation 2014/118/EU on monitoring of BFRs in food products for majority of the compounds. The concentrations of polybrominated diphenyl ethers (PBDEs) in real samples determined by HPLC-APPI-Orbitrap-MS method and validated gas chromatography–high-resolution mass spectrometry (GC–HRMS) method were found to be in a good agreement.

Ultra-trace measurement of Dechloranes to investigate food as a route of human exposure

Dechloranes, including Dechlorane Plus (syn- and anti-isomers), Dechlorane 602, Dechlorane 603, Dechlorane 604, Chlordene Plus, and Mirex are used as flame-retardants and were recently found in human serum of the European population. In order to investigate if food consumption would possibly be a significant route of exposure, we developed a method for the measurement of Dechloranes in food and feed. We showed that it was possible to extend the scope of the regular polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin like (DL-), and non-dioxin like (NDL-) regulated PCBs clean-up and fractionation procedure to Dechloranes and that no compound degradation occurred during the strong acidic treatments used for lipid digestion. Dechloranes were measured by gas chromatography coupled to triple quadrupole mass spectrometry (GC-QQQMS/MS). We optimized injection parameters by face centered experimental design (FCD). The electron ionization fragmentation was investigated to set appropriate multiple reaction monitoring (MRM) transitions. Instrumental and method limits of quantitation (iLOQs and mLOQs) were determined following EU guidelines for dioxin analyses in food. A total of 88 samples were analyzed to assess the prevalence of this route of exposure to humans. Average levels of the sum of Dechloranes ranged from 10 to 31pg/g fat, with the exception of fish, feed additives, and corn that were reported in pg/g wet weight at average levels of 9, 12, and 2pg/g ww. Based on Belgian food habits, a dietary intake was estimated to be 136pg/day. The relatively low reported levels indicate that other routes of human exposure should be considered.

Development and validation of a high performance liquid chromatographic method for simultaneous determination of vitamins A and D3 in fluid milk products.

An HPLC method for simultaneous determination of vitamins A and D3 in fluid milk was developed and validated. Saponification and extraction conditions were studied for optimum recovery and simplicity. An RP HPLC system equipped with a C18 column and diode array detector was used for quantitation. The method was subjected to a single-laboratory validation using skim, 2% fat, and whole milk samples at concentrations of 50, 100, and 200% of the recommended fortification levels for vitamins A and D3 for Grade "A" fluid milk. The method quantitation limits for vitamins A and D3 were 0.0072 and 0.0026 μg/mL, respectively. Average recoveries between 94 and 110% and SD values ranging from 2.7 to 6.9% were obtained for both vitamins A and D3. The accuracy of the method was evaluated using a National Institute of Standards and Technology standard reference material (1849a) and proficiency test samples.

Novel polystyrene/antibody nanoparticle-coated capillary for immunoaffinity in-tube solid-phase microextraction.

Antibody-coated polystyrene (PS) nanoparticles (denoted as PS/IgG) were prepared and chemically immobilized for the first time onto a capillary inner wall for immunoaffinity in-tube solid-phase microextraction (SPME) of β2-microglobin (β2MG) and cystatin C (Cys-C). Scanning electron microscopy images of the prepared capillary showed that the nanoparticles were evenly coated onto the capillary inner surface, resulting in the undulating surface of the capillary inner wall. The extraction capacity of the nanoparticle-coated capillary was nearly five times higher than that of a monolayer antibody-immobilized capillary. The in-tube SPME recovery of β2MG (or Cys-C) by the nanoparticle-functionalized capillary was more than 97.8%, whereas that by the monolayer antibody-immobilized tube was 30.5%. In addition, the method quantitation limit obtained by using the nanoparticle-coated capillary was ten times lower than that by the monolayer capillary. Therefore, the capillary coated by PS/IgG nanoparticles is more suitable for immunoaffinity in-tube SPME compared with the commonly used monolayer antibody-immobilized capillary.