Detection Limit Of Method Research Articles

Risk assessment of nickel through Portuguese homemade baby foods

Children are the most vulnerable population group to food contaminants. Nickel is a human carcinogen and exposure to this metal occurs mainly through ingestion of contaminated food. Therefore, this study was conducted to evaluate the risk posed by the exposure of children to nickel through homemade food in Portugal. The analytical methodology used for the determination of nickel was dry ashing followed by graphite furnace atomic absorption spectrometry which allowed for a method detection limit of 17.4 µg kg−1. Samples (n = 146) of homemade food were analysed, including soups, main courses, fruits and non-commercial paps. From these, 121 (82.9%) were contaminated, with the non-commercial paps presenting the highest average (134 µg kg−1) and maximum (350 µg kg−1) nickel concentrations. These results were similar to those obtained for Portuguese commercial premade baby foods, discarding the possibility of nickel migration from the containers and lids alloys. Moreover, the estimated daily intake did not surpassed the actual tolerable daily intake for the different age groups, when using both average results and the worst case scenario.

Detection of multiple prohibited ingredients in nutritional supplements in a case of doping

We present a case of a mixed martial art athlete found positive to methasterone metabolites, ligandrol and cardarine metabolites after an anti-doping testing. The athlete denied any drugs consumption but provided the list of 23 nutritional supplements under use during competition. The aim of the present study was to analyse the provided material to support evidence of unintentional doping. Cumulatively, products were commercialised either as pre-workout, intra-workout and post-workout adjuvants containing amino acids, creatine and proteins or as cofactors and vitamins to recover after training. Four products were taken to aid sleeping and one was a “testosterone boost”. All samples were submitted to analysis by liquid-chromatography/high resolution mass spectrometry (LC-QTOF). One hundred milligrams of material (powders, pills, oily pills, capsules) were sampled and dissolved with 10 mL of methanol, vortexed for 30 and sonicated for 30 min. The extracts were centrifuged at 3000 rpm for 5 min at 25 °C. The supernatants were appropriately diluted with deionised water then 5 μL injected into the LC-MS. Separations were carried out in a Zorbax C18 (2.1 × 100, 1.8 μm) column in 5 mM ammonium formate (mobile phase A) and methanol (mobile phase B), both added of 0.1% formic acid, flow at 0.2 mL/min. Acquisitions were carried out in positive polarity MS scan mode and MS/MS for fragment confirmation. Sensitivity expressed as method detection limit (MDL), linearity, carry-over, dilution integrity, accuracy and precision were tested under the described conditions for cardarine, methasterone and ligandrol. The analysis of the samples showed 2 out the 23 nutritional products containing the illicit substances. Methasterone, cardarine and ligandrol were alongside present in one sample (S1) at the respective concentrations of 5 μg/mg, 11.8 μg/mg and 1.4 μg/mg. Cardarine and ligandrol were confirmed in a second sample (S2) at the concentration of 0.6 and 0.2 μg/mg, respectively. Two products resulted contaminated with methasterone, cardarine and ligandrol. The calculated concentration for all substances > 1 μg/mg in S1 product may presume an intentional manipulation with pharmacologically active ingredients that better fitted the promise of enhanced recovery and improved endurance. In S2 ligandrol and cardarine amounts are compatible with a cross-contamination scenario. Conclusion: methasterone, ligandrol and cardarine were complessively detected in 2 samples. Since no labelling declared the retrieved substances, this might have represented a case of unintentional doping.

Detecting trace dissolved organic nitrogen (DON) in freshwater by converting DON rapidly into nitrate with VUV/H2O2 pretreatment

Dissolved organic nitrogen (DON) plays a key role in many biogeochemistry and engineering processes such as forming nitrogenous disinfection byproducts. However, detecting aqueous DON at trace levels is challenging currently because conventional DON conversion methods have very high method detection limits (MDL). In addition, DON is measured indirectly by subtracting dissolved inorganic nitrogen (DIN) from total dissolved nitrogen (TDN), which can propagate analytical errors of each analyte. In order to solve these issues, we isolated DON from DIN with electrodialysis before and herein tested vacuum ultraviolet (VUV) in tandem with several oxidants to convert DON completely into nitrate for subsequent N analysis. Results showed that H2O2 was more suitable than chlorine and persulfate because VUV/chlorine or VUV/persulfate is either inefficient to convert DON or subjected to nonnegligible N loss. To verify the efficiency, we evaluated the effects of typical water and operating variables on the conversions of four model DON compounds and their yields of nitrate. Under optimal conditions (pH 10.3 and 500 mg/L H2O2), the process converted DON completely into nitrate within just 60 min. Compared to conventional TDN analytical methods, the VUV/H2O2 method features not only better analytical precision but also lower MDL because the formed nitrate can be analyzed at very low MDL by ion chromatography (IC). So, this approach moves one step further to achieve a conceptually new DON analytical method by coupling electrodialysis, VUV/H2O2, and IC.

Synthesis and Characterization of a Biodegradable and Robust Film Using Gracilarialichenoides and Sargassumhorneri for Packaging Applications

In this study, a biodegradable and mechanically robust film was synthesized using seaweeds (Gracilarialichenoides and Sargassumhorneri), and its physicochemical and mechanical properties were characterized. In addition, its applicability in the packaging area was studied. A synthetic process including cleaning, drying, softening, pulping, and forming was developed. The microscopic morphology of the developed biodegradable film was similar to wood-based paper. In order to characterize its chemical composition and structure, FE-SEM, FT-IR, GC-MS, and TGA analyses have been performed. In addition, an aerobic biodegradability test was performed in accordance with ISO 14855-1:2012. From those experimental studies, it was shown that the major ingredient of the developed material is cellulose and other bio-originated organic substances. The developed seaweed-based film has excellent biodegradability which is 17 times higher than biodegradable polybutylene succinate (PBSe, hereafter) film, and seven times higher than other seaweed-based film in literature. The tensile strength of the film was enhanced by more than 40% compared with other seaweed-based film of previous studies. A hazardous material test was conducted in accordance with IEC62321, and the result indicated that all of the concerned toxic material was estimated to be under the method detection limit (MDL). Based on the aforementioned results, a prototype egg carton was successfully developed in accordance with ISO 534.

Applied Research Note: Combination of probiotic and prebiotic impacts Salmonella Enteritidis infection in layer pullets

Mitigation of food pathogens such as Salmonella continues to be a focus in poultry production, whether on shell eggs or meat products. No single approach is fully able to eliminate the risk of Salmonella contamination, but rather comprehensive programs are used in a multi-faceted approach. Targeted in-feed additives are a component of a food safety program and may help to reduce Salmonella infection. This study was aimed to evaluate the efficacy of a probiotic and prebiotic combination feed-additive product to reduce Salmonella Enteritidis (S.E.) infection in layer pullets. A total of 192 day-old pullets were placed in cages in two treatments (Control and pre-probiotic combination product at 1.5 lb/ton/of complete feed). Birds were challenged with 1.8 × 10 9 colony forming units (CFU) per bird of S.E. on Day 21 of the trial. Twenty-four birds from each treatment were sampled 6, 10, 14 and 18 days post infection (dpi). Cecal pouches were collected for enumeration of S.E. using plate counting technique. S.E. counts were numerically lower in Treatment 2 compared to Treatment 1 at 14 and 18 dpi, as Salmonella shedding in the course of infection was declining. Mean S.E. count in the ceca of pullets in Treatment 2 was 0.54 log 10 lower than that of Treatment 1 (3.36 log10) at 18 dpi. Samples below the detection limit of the counting method were significantly (p=0.021) higher in 10/24 (41.7%) of the pullets in Treatment 2 compared to 3/24 (12.5%) Treatment 1 at 18 dpi. Therefore, addition of the dietary pre- and probiotic combination product resulted in lower S.E. shedding in layer pullets challenged with S.E.

A Core-Shell Amino-Functionalized Magnetic Molecularly Imprinted Polymer Based on Glycidyl Methacrylate for Dispersive Solid-Phase Microextraction of Aniline

A core-shell amino-functionalized glycidyl methacrylate magnetic molecularly imprinted polymer (MIP) was synthesized by the suspension polymerization/surface imprinting method and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), mercury porosimetry, nitrogen gas adsorption–desorption, and elemental analysis. This MIP was used as the sorbent in dispersive solid-phase microextraction (DSPME) of aniline from textile wastewater prior to high-performance liquid chromatography-mass spectrometry (HPLC-MS) measurements. Since aniline is toxic and a probable human carcinogen, its determination in water is of great significance. This is a challenging task because aniline is usually present at trace levels. The effects of different DSPME variables on the preconcentration efficiency have been studied by using the Plackett–Burman screening design of experiments (DoE) followed by response surface methodology optimization using the Box-Behnken design. Thus, DoE enabled the investigation of several variables simultaneously. Under optimized conditions, aniline was effectively and selectively separated by a small amount of the DSPME sorbent and detected in real textile wastewater samples. The method detection limit of 1 ng mL−1 was attained, with good method linearity and acceptable recovery and precision. The results showed that the studied MIP could be a reliable DSPME sorbent for efficiently analyzing trace aniline in real wastewater samples.

Determination of pesticides and their degradation products in sediment samples by accelerated solvent extraction and solid-phase extraction with high-performance liquid chromatography-high-resolution mass spectrometry.

A new sensitive and selective methods was developed to quantify different types of pesticides and their degradation products in sediment. The method developed was optimized and modified based on the accelerated solvent extraction, followed by the solid-phase extraction clean-up technique. High-performance liquid chromatography coupled with mass spectrometry was used for analysis. The influence of various parameters on the extraction process was investigated, including the extraction temperature, extraction solvent, purification column and purification solvent, etc. Under the optimal conditions, the relative recoveries of the pesticides and their degradation products ranged from 80 to 106% for spiked blank sediment and environmental sediment samples with relative standard deviations of 1-9%. The method displayed low method detection limits for both sediment matrices and achieved good linearity over the tested range of concentrations. The physical and chemical properties of sediment showed that high content of sediment water content and humic acid would affect the extraction efficiency of sample pretreatment. The method was applied to environmental sediment to quantify pesticide residues in the samples. Based on the instrument and method performance validation results, the developed methods can be applied in environmental pesticide residue analysis, thus providing a scientific method for the detection of sediment samples.

Electrochemical Sensing of Chlorpyrifos, a Carcinogen Responsible for Breast Cancer, in Milk and Plasma of Lactating Mothers

AbstractIn view of the increase in breast cancer cases at the global level, electrochemical sensing of the carcinogenic pesticide, chlorpyrifos (CPF) in breast milk is proposed. The determination is based on the nucleophilic substitution reaction of pralidoxime (PAM) with CPF. The proposed method offers a linear concentration range of 0.002 to 0.08 μmol/L. The limit of detection and limit of quantification was found to be 0.05×10−9 and 0.167×10−9M, respectively. The offered “unmodified edge plane pyrolytic graphite sensor” proved to be a better substrate than the earlier reported modified sensors. The limit of detection for the proposed method was found to be nearly fifty times lower than reported at modified electrodes. The interference study proved the adequate selectivity of the offered sensor. The sensor has good stability and reproducibility along with high sensitivity. The offered sensor is very useful for cancer hospitals, pesticide industries, and the study of environmental toxicity‐related issues.

Application of wastewater-based epidemiology for estimating population-wide human exposure to phthalate esters, bisphenols, and terephthalic acid

Phthalates, bisphenols (BPs), and terephthalic acid (TPA) are widely used plasticizers and monomers in plastic manufacturing. Most of them are known to have an adverse effect on the human body, functioning as endocrine disruptors and suspected carcinogens. Access to near real-time data on population exposure to plasticizers is essential for identifying vulnerable communities and better protecting and managing public health locally. The objective of the present study was to evaluate population-level exposure to phthalates, BPs, and TPA by measuring urinary metabolites in community wastewater. Composited community wastewater (24-h samples) from five sewer sub-catchments of a southwestern city within the United States were analyzed for urinary biomarkers of phthalates, BPs, and TPA using solid-phase extraction-liquid chromatography-tandem mass spectrometry in conjunction with the isotope dilution method for absolute quantification. Ten of 16 analytes were detected at least once in community wastewater above the method detection limit (MDL), with MDLs ranging from 37 to 203 ng/L. The population normalized mass load of TPA was the highest, followed by the human metabolite of di-(2-ethylhexyl) phthalate (DEHP). Bisphenol S and monoethyl phthalate were detected with the highest frequency. Study findings suggest that analyzing municipal wastewater for chemical indicators of human exposure to plastic constituents is feasible, practicable, and informative, as long as appropriate steps are taken to determine, quantify and account for background levels of plastic analytes in the laboratory environment.

An effective method for pesticide residues and related compounds determination in air by GC-MS/MS to evaluate occupational exposure of workers and pesticide users

ABSTRACT Pesticide application is generally carried out by aerial or land spraying and part of what is applied can be transferred to the atmosphere. Despite considerable research on pesticides in the air, most studies have focused on a small number of compounds and emphasised the volatile pesticides, with little attention to current-use pesticides. Therefore, a reliable method was developed and validated for the multiresidue determination of 37 pesticides and 11 metabolites or related compounds in air samples. The method was based on an active sampling for 8 h using solid-phase traps containing Tenax® TA, direct extraction of the analytes from the traps with acetone, and determination by gas chromatography with tandem mass spectrometry (GC-MS/MS) in a triple quadrupole system. The method conditions were optimised using design of experiments. Compound recoveries (evaluated between 0.6 and 4.8 µg m−3) ranged from 71 to 114%, all with relative standard deviation ≤ 17%. The practical method limits of quantification were from 0.6 to 1.2 µg m−3 and the method limits of detection were from 0.2 to 0.4 µg m−3. The proposed method proved to be effective and comprehensive in terms of the classes and volatility of compounds that can be determined simultaneously at very low limits, with potential for application in occupational exposure and environmental monitoring.

Optimization and automation of rapid and selective analysis of fatty acid methyl esters from aqueous samples by headspace SPME arrow extraction followed by GC–MS/MS analysis

The analysis of fatty acid methyl esters (FAMEs) is of high relevance for monitoring and control of various industrial processes and biological systems. In this study, a novel, green analytical approach for the determination of 24 FAMEs from aqueous samples is proposed, which is based on a headspace solid-phase microextraction (SPME) arrow followed by gas chromatography coupled to tandem mass spectrometry (GC–MS/MS). The method was substantially accelerated to a run time of 44 min per sample by thorough optimization and automation of the relevant parameters. The limiting parameters, mostly based on expediting equilibrium attainment, were found to be parameters of extraction: material, pH, time, and temperature, which were optimized to divinylbenzene polydimethylsiloxane (DVB-PDMS), pH 2, 20 min, and 70 °C, respectively. The optimization and automation of the method led to low method detection limits (9–437 ng L−1) and high selectivity. Evaluation of the method on real samples was done by analyzing the aqueous phase of a bioreactor, whereby the matrix effect could be greatly reduced due to dilution and headspace sampling. The rapid, sensitive, selective, and matrix-reduced approach is found to be not only a novel method for water analysis but is promising for further applications, e.g., with solid and gaseous samples containing FAMEs.Graphical abstract

Managing argon interference during measurements of 18O/16O ratios in O2 by continuous-flow isotope ratio mass spectrometry

Monitoring changes in stable oxygen isotope ratios in molecular oxygen allows for studying many fundamental processes in bio(geo)chemistry and environmental sciences. While the measurement of ^{18}O/^{16}O ratios of mathrm {O}_{2} in gaseous samples can be carried out conveniently and from extracting moderately small aqueous samples for analyses by continuous-flow isotope ratio mass spectrometry (CF-IRMS), oxygen isotope signatures, updelta ^{18}O, could be overestimated by more than 6permille because of interferences from argon in air. Here, we systematically evaluated the extent of such Ar interferences on ^{18}O/^{16}O ratios of mathrm {O}_{2} for measurements by gas chromatography/IRMS and GasBench/IRMS and propose simple instrumental modifications for improved Ar and mathrm {O}_{2} separation as well as post-measurement correction procedures for obtaining accurate updelta ^{18}O. We subsequently evaluated the consequences of Ar interferences for the quantification of O isotope fractionation in terms of isotope enrichment factors, upepsilon _{mathrm {O}}, and ^{18}O kinetic isotope effects (^{18}O KIEs) in samples where mathrm {O}_{2} is consumed and Ar:mathrm {O}_{2} ratios increase steadily and substantially over the course of a reaction. We show that the extent of O isotope fractionation is overestimated only slightly and that this effect is typically smaller than uncertainties originating from the precision of updelta ^{18}O measurements and experimental variability. Ar interferences can become more relevant and bias upepsilon _{mathrm {O}} values by more than 2permille in aqueous samples where fractional mathrm {O}_{2} conversion exceeds 90%. Practically, however, such samples would typically contain less than 25 upmuM of mathrm {O}_{2} at ambient temperature, an amount that is close to the method detection limit of ^{18}O/^{16}O ratio measurement by CF-IRMS.Graphical abstract

Bismuth fire assay preconcentration and empirical coefficient LA-ICP-MS for the determination of ultra-trace Pt and Pd in geochemical samples

In this work, a novel method of solid sample pretreatment technique of bismuth fire assay (Bi-FA) combined with solid sample determination by laser ablation ICP-MS (LA-ICP-MS) was reported for the determination of ultra-trace Pt and Pd in geochemical samples. Bismuth oxide (Bi2O3) was used as fire assay collector to directly enrich Pt and Pd from solid samples, and Ag protection cupellation was employed to generate Ag granules. After cleaning, weighing and annealing, the Ag granules were compressed into thin slices and determined by LA-ICP-MS for 195Pt, 105Pd and 109Ag (109Ag was selected as the internal standard isotope). Bi2O3 provided exceptionally low blanks compared to nickel oxide and lead oxide commonly employed in fire assay procedures, and could be applied directly without purification. Different from traditional empirical coefficient method, the Chinese Certified Reference Materials (CRMs) for Pt and Pd were treated by the same procedure to obtain completely matrix matched Ag slices. And then modified empirical coefficient method and internal standard calibration strategy was used to reduce the instability of LA-ICP-MS, and random multipoint laser ablation was employed to further reduce analytical variation resulting from heterogeneity of Pt and Pd in the Ag slice. Under optimal conditions, excellent calibration curves for Pt and Pd were obtained (0.407–2958 μg g−1 and 0.407–2636 μg g−1, respectively), with correlation coefficients exceeding 0.9996. The method detection limits for Pt and Pd were 0.074 and 0.037 ng g−1, respectively. The established method was applied successfully to analysis of real geochemical samples, with determined values in good agreement with the results of traditional Pb-FA graphite furnace atomic absorption spectrometry (GF-AAS), and spiked recoveries between 87.8 and 125.0%.

Determination of polychlorinated naphthalenes in ambient air by isotope dilution gas chromatography-triple quadrupole mass spectrometry

环境空气中的多氯萘(PCNs)一般为痕量水平(pg/m3),要实现其准确定量必然对分析方法的提取、净化和仪器分析提出较高要求。研究通过考察提取溶剂种类、净化流程和色谱-质谱参数,建立了加速溶剂萃取(ASE)-多层硅胶复合中性氧化铝柱的净化方法,并利用同位素稀释气相色谱-三重四极杆质谱(GC-MS/MS)对环境空气中的多氯萘进行测定。同时,通过在采样、提取和进样分析前分别添加同位素内标,开展质量控制和保证。结果表明,在2~100 ng/mL范围内3~8氯萘的平均相对响应因子(RRF)的相对标准偏差(RSD)均小于16%。PCNs同类物的方法检出限为1~3 pg/m3(以样品体积为288 m3计算)。采用基质加标法评价了方法对环境空气样品中PCNs测定的精密度和准确度,低、中、高加标水平下3 ~8氯萘的平均加标回收率分别为89.0%~119.4%、98.6%~122.5%和93.7%~124.5%,测定结果的平均相对标准偏差分别为1.9%~7.0%、1.6%~6.6%和1.0%~4.8%。整个分析过程中,采样内标和提取内标的平均回收率分别为136.2%~146.0%和42.4%~78.1%, RSD分别为5.6%~7.5%和2.7%~17.5%,满足痕量分析的要求且平行性较好。方法的灵敏度和准确度高,精密度良好,适用于环境空气中3~8氯萘的准确定量测定,可在一定程度上缓解多氯萘监测对高分辨气相色谱-高分辨质谱的依赖,为实现多氯萘的国际履约提供方法支持。

Development of Simultaneous Analytical Methods of 37 PFAS in Drinking Water and Sediment Samples

Per-and polyfluoroalkyl substances (PFAS) are synthetic chemicals that exhibit various physicochemical characteristics, making it difficult to analyze many PFAS simultaneously. In this study, the simultaneous analytical methods of 37 per- and polyfluoroalkyl substances (PFAS), including the PFAS alternative compounds Gen-X, ADONA, Major F53B, Minor F53B, and precursors FOSA, FOSAA, MeFOSAA, EtFOSAA, n:2 FTUA, n:3 FTCA, and n:2 FTS in drinking water and sediment samples were developed using liquid chromatography-tandem mass spectrometry based on the Korean persistent organic pollutants (POPs) standard method. The water samples were extracted using a WAX cartridge by solid-phase extraction, while the sediment samples were extracted by ultrasonic extraction. The accuracy and precision satisfied the values of 50.7–118% and 0.01–8.5%, respectively, with a method detection limit of 0.12–1.36 ng/L. The PFAS analytical method for sediment samples was modified based on the Korean standard analytical method for persistent organic pollutants. The accuracy and precision of the 37 target PFAS ranged from 63% to 129% and 0.6% to 11.7%, respectively, with method detection limits of 0.03–1.94 ng/g in sediment. Satisfactory results were obtained for water samples using the current Korean standard analytical method for POPs. Meanwhile, for sediment samples, owing to the poor results obtained for the two compounds, the method was modified.

Efficient determination of BTX compounds based on UiO-66-diatomite composite enrichment and thermal desorption GC–MS

In this work, a UiO-66-diatomite composite was synthesized and used as sorbent to sample benzene, toluene and xylene (BTX) in indoor air. The physicochemical features of the as-prepared composite were deeply characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermo-gravimetric analysis (TGA) and nitrogen adsorption–desorption isotherm analysis. Moreover, an efficient analysis method for the enriched BTX compounds by the UiO-66-diatomite composite was successfully developed using thermal desorption (TD)-GC–MS technique. The influence of desorption temperature was investigated to optimize the operation conditions. Under the desorption temperature of 180 °C, the method depicted good linearity (R2 > 0.99) in the range of 5 ng to 1000 ng as well as excellent reproducibility with relative standard deviation (RSD) between 0.6% and 3.5%, in which the satisfactory recovery was achieved from 75.2% to 115%. More importantly, the developed method also exhibited high sensitivity with the method detection limit (MDL) in the range of 0.04–0.09 μg m−3. Hence, the findings evidence that this method might be one of the promising routes to detect trace levels of BTX compounds in indoor air and the MOF-based composite is feasible to be used as sorbent for the capture of volatile organic compounds in air.

Amperometric method for the determination of cellulase activity and its optimization using response surface method

Cellulases are a group of enzymes, which catalyse different steps of cellulose hydrolysis, and are broadly used in industry as unpurified mixtures of several enzymes. The total activity of cellulase is defined as the ability of the enzyme to produce glucose, which is the final product of cellulose hydrolysis, and is expressed in cellulase units. However, common strategies for the determination of the cellulolytic activity of industrial cellulase preparations are based on the assessment of different steps of cellulose hydrolysis, and the results obtained with different methods are not similar. The aim of the present study was to develop an assay for the determination of cellulase activity that relies on the amperometric determination of the final product of cellulose hydrolysis glucose. The assay conditions were optimized using response surface methodology (RSM) combined with Box-Behnken design. The detection limit of the proposed method was 1.71 ± 0.06 U. We compared the results of the amperometric method with the ones obtained with the spectrophotometric method and viscosimetry in a commercial cellulose preparation.

A cleanup method of serum extracts with molecular sieves as SPE sorbents for the analysis of polybrominated diphenyl ethers.

Based on the size- and shape-selective sorption, 13X molecular sieves were developed as solid-phase extraction adsorbents to cleanup serum extract for the determination of polybrominated diphenyl ethers. The important parameters affecting the cleanup efficiency were investigated including the amount of sorbents, the type, and volume of solvents. Under the optimized conditions, the capacity for removing impurities was evaluated via gel permeation chromatography and gas chromatography with mass spectrometry. The results demonstrated that up to 99% of lipids in corn oil (13 mg) can be removed after cleanup, and endogenous compounds in serum can also be effectively eliminated. The cleanup efficiency is not only superior to hydrophile-lipophile balance column, but also close to acid silica gel and multifunction impurity sorbents. Generally, the developed cleanup method exhibited higher recovery for polybrominated diphenyl ethers with more than four bromines, especially for nona- and deca-brominated diphenyl ethers (99.1-117.8%). The cleanup method can be coupled with gas chromatography and tandem mass spectrometry for polybrominated diphenyl ethers analysis in human serum. The method detection limits were 0.01-0.27 ng/mL and average recovery was 50.9-113.3%, except 2,3',4',6-tetrabrominated, 2,3',4,4',6-pentabrominated, and 2,3,3',4,4',5',6-heptabrominated diphenyl ethers. 2,2',4,5'-Tetrabrominated diphenyl ethers had the highest detection frequency (95%) in human serum, whereas decabrominated diphenyl ethers had the maximum mean concentration (0.50 ng/mL).

Chemometric Optimization of Solid-Phase Extraction Followed by Liquid Chromatography-Tandem Mass Spectrometry and Probabilistic Risk Assessment of Ultraviolet Filters in an Urban Recreational Lake

Solid-phase extraction (SPE) of eleven ultraviolet filters (UVFs): benzophenone-1 (BP-1); benzophenone-3 (BP-3); benzophenone-4 (BP-4); isoamyl p-methoxycinnamate (IAMC), homosalate (HMS); 4-hydroxybenzophenone (4-HB); 4-methylbenzylidene camphor (4-MBC); octocrylene (OC); octyl dimethyl-p-aminobenzoate (OD-PABA); 2-ethylhexyl-4-methoxycinnamate (EHMC); and avobenzone (AVO), has been optimized using Plackett-Burman design, Box-Behnken design, and Derrindzer desirability function. Of the six SPE variables studied, the most influencing is the type of eluent followed by pH and the methanol content in the rinsing solvent. A method with good analytical performance was obtained by applying optimal SPE conditions and liquid chromatography-tandem mass spectrometry (LC-MS/MS), with the method detection limit ranging from 0.1 to 5 ng/L, recovery from 44% to 99%, and relative standard deviation (RSD) within 19%. This method was used to analyze the content of UVFs in an urban lake (Sava Lake, Serbia). UVFs occurrence, geostatistical distribution, and associated environmental risk are highly dependent on recreational activities. The average concentrations of UVFs ranged from 0.3 to 113 ng/L, and the most present substance was EHMC, followed by 4-MBC and BP-3. The spatial distribution of the risk quotient (RQ = 0.04–1.7) inside the lake is highly correlated with the number of people bathing and swimming. Human exposure through the dermal pathway is higher than ingestion for most UVFs. Monte Carlo simulation of probabilistic risk assessment estimated the percentile P10, P50, P90 of 12.7; 17.3; 47.5 and 20.1; 27.6; 77.5 ng/kg∙day for total human exposure of adults and children, respectively. The sensitivity analysis revealed that the health risk estimate depends mostly on the content of EHMC, HMS, and 4-MBC, while the most influential exposure variables were human body weight and skin surface area. There is no serious concern to human health due to UVFs in the short term; however, a high ecological risk in some parts of the lake is estimated.

Development of Simultaneous Analytical Method for Imidazolinone Herbicides from Livestock Products by UHPLC-MSMS.

A simultaneous analytical method, which used LC/MSMS for imidazolinone herbicides from livestock products (egg, milk, beef, pork, and chicken) for monitoring, was developed with a QuEChERS preparation. A weighed sample (5 g) in a 50 mL conical tube was added to 0.1 M potassium phosphate dibasic solution (5 mL) and shaken for 10 min. After shaking, 0.5 mL of 6 N HCl and 5 mL of acetonitrile were added, and this solution was shaken for 10 min. Additionally, QuEChERS extraction salts (original method, 4 g MgSO4, 1 g NaCl) were added to the sample in a 50 mL conical tube. The mixture was strongly shaken for 1 min and centrifuged at 3000× g for 10 min. The acetonitrile layer was purified with dSPE (150 mg MgSO4, 25 mg C18) and was centrifuged at 13,000× g for 5 min. The supernatant was filtered with a membrane filter (pore size: 0.2 μm) before analysis. The ME (%, matrix effect) range for almost all analytes was −6.56 to 7.11%. MLOD (method limit of detection) and MLOQ (method limit of quantitative) values were calculated by the S/N ratio. MLOQs were 0.01 mg/kg. The linear correlation coefficients (R2) were >0.99 with the range of 0.5~25 μg/kg for all of the imidazolinone herbicides. The recoveries (of imidazolinone herbicides) were in the range of 76.1~110.6% (0.01 mg/kg level), 89.2~97.1% (0.1 mg/kg level), and 94.4~104.4% (0.5 mg/kg level). These are within the validation criteria (to recover 70–120% with RSD <20%). The method demonstrated the simple, rapid, high throughput screening and quantitative analysis of imidazolinone herbicide residues for monitoring in livestock products.