Rapid Apta-Chromogenic Detection Method for Nitrofuran Metabolite Determination.

Nitrofuran (NF) contamination in food products is a global problem resulting in the banned utilization and importation of nitrofuran contaminated products. A novel chromogenic detection method using a specific DNA aptamer with high affinity and specificity to nitrofurans was developed. Single-stranded DNA aptamers specific to nitrofuran metabolites, including 3-amino-2-oxazolidinone (AOZ), 3-amino-5-methylmorpholino-2-oxazolidinone (AMOZ), and 1-aminohydantoin (AHD), were isolated using magnetic bead-SELEX. The colorimetric detection of nitrofurans using gold nanoparticles (AuNPs) exhibited an AOZ detection range of 0.01-0.06 ppb with a limit of detection (LOD) of 0.03 ppb. At the same time, this system could detect AMOZ and AHD at a range of 0.06 ppb and 10 ppb, respectively. The fast nitrofuran extraction method was optimized for food, such as fish tissues and honey, adjusted to be completed within 3-6 h. This novel apta-chromogenic detection method could detect NF metabolites with a sensitivity below the minimum required performance limit (MPRL). This analysis will be valuable for screening, with a shortened time of detection for aquaculture products such as shrimp and fish muscle tissues.

Accelerated decomposition of the fungicide, iprodione, on TiO2 surface under solar irradiation: experimental study and DFT mechanisms.

In the present work we have studied photo-induced decomposition of iprodione on silica support with different additions of titanium dioxide. Both the experimental and theoretical (DFT) approaches have been applied. It was found that 16 hours visible light exposure of the samples with 0.1% and 1.0% of TiO2 leads respectively to 48.28% and 21.05% of residual amounts of iprodione in these samples. A number of intermediates and end products were identified by means of GS-MS and LC-MS chromatography. The iprodione isomer (RP 30228) and its decay product 1-(3,5-dichlorophenyl)-5-isopropyl biuret (RP 36221) were identified among them. Our DFT calculations have revealed the detailed mechanisms of formation of the above products and the mechanism of accelerated proton-induced decomposition of iprodione molecules adsorbed on the TiO2 surface. Also, the intra-molecular reasons for iprodione stability in acidic media were clarified together with the mechanism of hydantoin cycle opening under the action of hydroxyl anions.

QSAR characterization of new synthesized hydantoins with antiproliferative activity.

Hydantois have been identified as constituents of a number of pharmacologically active molecules. In the present study, we have examined in vitro antiproliferative activity against human colon cancer cell lines HCT-116 of three series of 3-(4-substituted benzyl)-hydantoins with various substituent attached in position 5 of the hydantoin ring. Since the investigated compounds have recently been synthesized and show antiproliferative activity, a good understanding of the properties of the potential drug responsible for their pharmacokinetics is an important goal for their further development. One of the important properties is lipophilicity. Lipophilicity has been assessed by reversed-phase liquid chromatography (high-performance thin-layer chromatography and high-pressure liquid chromatography) by means of direct and indirect (using calibration curve) methods. Chromatographic lipophilicity indices in addition to calculated logP values were compared by hierarchical cluster analysis. The linear solvation energy relationship approach was used to understand and compare the types and relative strength of the molecular interactions that occur in the chromatographic as well as in the n-octanol-water partitioning systems. Finally, correlation between in silico pharmacokinetic predictors and antiproliferative activity was examined. Preliminary quantitative structure-activity relationship modeling indicates that pharmacokinetic predictors capture only one-quarter of all chemical features that are important for antiproliferative activity itself. Among selected descriptors are chromatographic lipophilicity indices.

A fluorescent immunochromatographic strip test using a quantum dot-antibody probe for rapid and quantitative detection of 1-aminohydantoin in edible animal tissues.

A rapid, simple, and sensitive fluorescent immunochromatographic strip test (ICST) based on quantum dots (QDs) has been developed to detect 1-aminohydantoin (AHD), a major metabolite of nitrofurantoin in animal tissues. To achieve this, QD-labeled antibody conjugates, which consist of CdSe/ZnS QDs and monoclonal antibodies, were prepared by an activated ester method. Under optimal conditions, with the nitrophenyl derivative of AHD as the target, the ICST had a linear range from 0.1 to 100 ng/mL, with a correlation coefficient of 0.9656 and a 50% inhibitory concentration of 4.51 ng/mL. The limit of detection was 0.14 ng/g, which was below the minimum required performance limit of 1 µg/kg for AHD established by the European Commission. The recoveries for AHD ranged from 81.5% to 108.2%, with coefficients of variation below 13%, based on intraday and interday analysis. Furthermore, for AHD in real samples, the ICST showed high reliability and high correlation with liquid chromatography-tandem mass spectrometry (correlation coefficient of 0.9916). To the best of our knowledge, this is the first report of a novel and sensitive method based on a fluorescent ICST to detect AHD below the minimum required performance limit. The ICST demonstrated high reliability, and could be ideally suited for rapid, simple, and on-site screening of AHD contamination in animal tissues. Graphical abstract A rapid, simple, and sensitive fluorescent immunochromatographic strip test that is based on quantum dots was developed to detect 1-aminohydantoin (AHD), a major metabolite of nitrofurantoin in animal tissues. 2-NBA 2-nitrobenzaldehyde, NP nitrophenyl.

Simultaneous determination of iprodione, procymidone, and chlorflurenol in lake water and wastewater matrices by GC-MS after multivariate optimization of binary dispersive liquid-liquid microextraction.

This study reports the optimization of a binary dispersive liquid-liquid microextraction method for the determination of iprodione, procymidone, and chlorflurenol by gas chromatography mass spectrometry. The study was aimed at using two extraction solvents to increase the extraction efficiency of all analytes. The binary solvents recorded results higher than the mono-solvents. After examining the effects of main experimental parameters and their interactions by analysis of variance, 200 µL of binary mixture (dichloromethane and 1,2-dichloroethane), 2.5 mL of ethanol, and 15 s vortex were obtained as optimum parameters. The detection and quantification limits calculated for the analytes were found to be between 0.30-1.6 and 1.0-5.3 ng/mL, respectively. Enhancement in detection power calculated as a ratio of the binary extraction detection limit to the detection limit of direct GC-MS analysis was 105-, 214-, and 233-fold for chlorflurenol, iprodione, and procymidone, respectively. In order to check the accuracy of the developed method, recovery study was performed. Water sampled from a lake and two wastewater samples from treatment facilities were spiked at two concentrations, and the percent recovery calculated for the samples ranged between 87 and 116%. These results confirmed the suitability of the method to real samples for accurate determination of the analytes at trace levels.

Atrazine, chlorpyrifos, and iprodione effect on the biodiversity of bacteria, actinomycetes, and fungi in a pilot biopurification system with a green cover.

The use of biopurification systems can mitigate the effects of pesticide contamination on farms. The primary aim of this study was to evaluate the effect of pesticide dissipation on microbial communities in a pilot biopurification system. The pesticide dissipation of atrazine, chlorpyrifos and iprodione (35 mg kg-1 active ingredient [a.i.]) and biological activity were determined for 40 days. The microbial communities (bacteria, actinomycetes and fungi) were analyzed using denaturing gradient gel electrophoresis (DGGE). In general, pesticide dissipation was the highest by day 5 and reached 95%. The pesticides did not affect biological activity during the experiment. The structure of the actinomycete and bacterial communities in the rhizosphere was more stable during the evaluation than that in the communities in the control without pesticides. The rhizosphere fungal communities, detected using DGGE, showed small and transitory shifts with time. To conclude, rhizosphere microbial communities were not affected during pesticide dissipation in a pilot biopurification system.

The influence of effective microorganisms (EM) and yeast on the degradation of strobilurins and carboxamides in leafy vegetables monitored by LC-MS/MS and health risk assessment.

The aim of this study was to determine the behaviour of strobilurin and carbocyamides commonly used in chemical protection of lettuce depending on carefully selected effective microorganisms (EM) and yeast (Y). Additionally, the assessment of the chronic health risk during a 2-week experiment was performed. The statistical method for correlation of physico-chemical parameters and time of degradation for pesticides was applied. In this study, the concentration of azoxystrobin, boscalid, pyraclostrobin and iprodione using liquid chromatography-mass spectrometry (LC-MS/MS) in the matrix of lettuce plants was performed, and there was no case of concentration above maximum residues levels. Before harvest, four fungicides and their mixture with EM (1 % and 10 %) and/or yeast 5 % were applied. In our work, the mixtures of 1%EM + Y and 10%EM + Y both stimulated and inhibited the degradation of the tested active substances. Adding 10%EM to the test substances strongly inhibited the degradation of iprodione, and its concentration decreased by 30 %, and in the case of other test substances, the degradation was approximately 60 %. Moreover, the addition of yeast stimulated the distribution of pyraclostrobin and boscalid in lettuce leaves. The risk assessment for the pesticides ranged from 0.4 to 64.8 % on day 1, but after 14 days, it ranged from 0.0 to 20.9 % for children and adults, respectively. It indicated no risk of adverse effects following exposure to individual pesticides and their mixtures with EM and yeast.

Computational analysis of the stereochemical outcome in the imidazolidinone-catalyzed enantioselective (4 + 3)-cycloaddition reaction.

Computations show why the catalytic, asymmetric (4 + 3)-cycloaddition reaction developed in the Harmata laboratories proceeds with facial selectivity opposite to that for models proposed for related catalyzed Diels-Alder reactions. Computations with M06-2X/6-311+G(d,p)//B3LYP/6-31G(d) show that iminium ions derived from MacMillan's chiral 2-tert-butyl-5-benzylimidazolidinone and siloxypentadienals undergo (4 + 3)-cycloadditions with furans preferentially on the more crowded face. Conformational reorganization of the benzyl group, to avoid intramolecular interaction with the silyl group, is responsible for differentiating the activation barriers of top- and bottom-face attack.

Preservatives in cosmetics in the Israeli market conform well to the EU legislation.

BACKGROUND: Preservatives are important and frequent skin sensitizers, found in a wide range of products for personal and occupational use. According to the European legislation, some cosmetic ingredients are restricted in terms of quantity and a detailed list of ingredients must be present on the product or packaging. OBJECTIVES: To examine the use of preservatives in common cosmetics on the Israeli market. MATERIALS/METHODS: Sixty different Israeli brand cosmetics, including shampoos, liquid soaps, body creams and hand creams were randomly selected. Ingredient labels were examined. The products were investigated by the chromotropic acid method for release of formaldehyde and by high performance liquid chromatography for the presence of formaldehyde, DMDM hydantoin and methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) and MI content. RESULTS: All products but one contained a detailed list of ingredients printed on the package. According to labelling, the most prevalent preservatives in Israeli shampoos and liquid soaps were DMDM hydantoin and MCI/MI. Hand creams and body creams contained mainly parabens but also iodopropynyl butylcarbamate, phenoxyethanol and DMDM hydantoin. Formaldehyde in doses from 4 to 429 ppm, and DMDM hydantoin were detected in 38 and 16 (63% and 27%) of the products, respectively. MCI/MI was detected in 11 (18%) of the products, with highest prevalence in rinse- off products (55%). Excluding one hand cream which measured 106 ppm MI, the amount of formaldehyde, DMDM hydantoin, MCI/MI and MI was within the allowed concentrations by the European directive in all cases. CONCLUSIONS: In Israel, adaptation of the European directive prevails, as shown by the measurements we performed on randomly selected products.

Reversed-phase TLC study of some long chain arylpiperazine of imidazolidine-2,4-dione and imidazo[2,1-f]purine-2,4-dione derivatives.

The chromatographic parameters of arylpiperazinylpropyl derivatives of imidazolidine-2,4-dione and imidazo[2,1-f]purine-2,4-dione were investigated using reversed-phase thin layer chromatography method. The results revealed that R(M0) of investigated compounds depended on substituent in arylpiperazinyl fragment as well as on a nature of (cycloalkyl)aromatic ring at 5 position of imidazolidine-2,4-dione and at 7 position of imidazo[2,1-f]theophylline. The R(M0) parameters were compared with computationally calculated partition coefficients values by principal component analysis (PCA). To verify the influence of lipophilic parameter of investigated compounds on their biological activity the statistical analysis of Mann-Whitney was performed.

Preparation of high-affinity and high-specificity monoclonal antibody and development of ultra-sensitive immunoassay for the detection of 1-aminohydantoin, the metabolite of nitrofurantoin.

1-Aminohydantoin (AHD), the residual marker of nitrofurantoin, is usually detected after derivatisation using the derivatisation reagent 2-nitrobenzaldehyde. Avoiding the antibody recognition of the derivatisation reagent is essential for the accurate detection of AHD residues. In this paper, a novel hapten called hapten D was designed, and then, a monoclonal antibody that did not recognise 2-nitrobenzaldehyde was prepared based on this novel hapten. An ultra-sensitive indirect competitive enzyme linked-immunosorbent assay (icELISA) was established under optimal conditions. The 50% inhibition concentration and limit of detection of AHD were 0.056 and 0.0060 ng/mL, respectively, which improved the sensitivity by 9-37-fold compared with the previously reported icELISA methods. The average recovery rates were 88.1%-97.3%, and the coefficient of variation was <8.6%. The accuracy and reliability of the icELISA were verified using liquid chromatography-tandem mass spectrometry. These results demonstrated that the developed icELISA is a useful and reliable tool.

Determination of total nitrofuran metabolites in shrimp muscle using liquid chromatography/tandem mass spectrometry in the atmospheric pressure chemical ionization mode.

The method of MacMahon and Lohne for analysis of nitrofuran metabolites in shrimp was optimized to streamline the extraction processes and the LC analysis. This revised method includes 16 h of mild acid hydrolysis/derivatization followed by ethyl acetate extraction and analysis by LC/MS/MS in the atmospheric pressure chemical ionization mode. This revised method was validated in shrimp for concentrations of 0.25 to 2.0 ng/g. The LOQ was 0.25 ng/g for all metabolites. The LOD was 0.052 nglg for 1-aminohydantoin (AHD), 0.206 ng/g for 3-amino-2-oxazolidinone (AOZ), 0.108 ng/g for semicarbazide (SC), and 0.062 ng/g for 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ). The spike recoveries with RSD into negative matrix at 1 ng/g were 100.2% (3.2%) for AHD, 102.5% (1.0%) for AOZ, 103.7% (2.3%) for SC, and 104.0% (3.3%) for AMOZ. The spike recoveries at 1 ng/g into unknown samples (n=108) containing varied levels of nitrofuran metabolites were 112.6% (25.7%) for AHD, 108.1% (12.1%) for AOZ, 103.0% (12.0%) for SC, and 100.3% (6.9%) for AMOZ. Interday precision with samples containing incurred AOZ concentrations of 0.92 to 17.8 ppb performed over a year was 10.4% RSD. The method is accurate and precise for determining nitrofuran concentrations in the edible tissue of shrimp.

Photostability of Iiovaline and its precursor 5-Ethyl-5- methylhydantoin exposed to simulated space radiations.

Aqueous solutions of isovaline and its precursor molecule, 5-ethyl-5-methylhydantoin, were irradiated with ultraviolet and γ-ray photons, to evaluate their structural stability against space radiation. The degree of photolysis was measured and irradiation products were identified using chiral, reversed-phase and ion-exchange high-performance liquid chromatography. The experimental results show that the degree of photolysis of 5-ethyl-5-methylhydantoin is more significant than that of isovaline under ultraviolet light irradiation, while the results under γ-ray irradiation are the opposite. As the products of isovaline photolysis, aspartic acid, serine, glutamic acid and alanine were dominantly detected.

Iprodione residues and dissipation rates in tobacco leaves and soil.

Field experiments were conducted in two different locations to determine the residue levels and dissipation rates of iprodione in tobacco leaves and soil. Iprodione 50% wettable powder formulation was sprayed once at 12.50 g/ha to study the dissipation behavior and three to four times at 8.33 g/ha (recommended dose) and 12.50 g/ha (1.5 times the recommended field dose) to determine the residue levels of iprodione in tobacco leaves and soil after repeated applications. Iprodione residues in both green tobacco leaves and soil dissipated to about 50% of the initial deposits after 7 days and then further dissipated to more than 90% after 35 days.The dissipation of iprodione followed first order kinetics and the calculated half-life values (T (1/2)) were 5.64-8.80 days in green tobacco leaves and 7.50-9.93 days in soil, respectively. Iprodione residue levels in flue-cured tobacco leaves 21 days after the third and fourth applications ranged from 7.61 to 40.98 mg/kg. Meanwhile, the residues detected in soil decreased to 0.010-0.117 mg/kg 21 days after the last treatment.

Determination of four nitrofuran metabolites in gelatin Chinese medicine using dispersive solid phase extraction and pass-through solid phase extraction coupled to ultra high performance liquid chromatography-tandem mass spectrometry.

This study established a validated analytical method for the first time on the determination of nitrofuran metabolites, including semicarbazide (SEM), 1-aminohydantoin (AHD), 3-amino-2-oxazolidinone (AOZ) and 3-amino-5-morpholinomethyl-2-oxazolinone (AMOZ) in gelatin Chinese medicine. A C18 column with the mobile phase consisting of acetonitrile and 5 mmol/L ammonium acetate in water was used to separate these nitrofuran metabolites. The limit of detection of SEM, AHD, AOZ and AMOZ were found to be 0.2 µg/kg, 0.3 µg/kg, 0.2 µg/kg and 0.2 µg/kg, whereas their limit of quantification were 0.6 µg/kg, 0.8 µg/kg, 0.6 µg/kg and 0.5 µg/kg. These nitrofuran metabolites exhibited a good linear standard curve (regression coefficients above 0.99) with a concentration range of 2 µg/L to 100 µg/L. Regarding extraction procedure, gelatin Chinese medicine was pre-treated with pepsin and then extracted using 5% formic acid (v/v) in acetonitrile. The resultant extract was purified through dispersive solid phase extraction using 1000 mg anhydrous sodium sulfate, 300 mg octadecyl carbon silica gel sorbent absorbent and 500 mg ethylenediamine-N-propyl carbon silica gel absorbent, and then further purified on Oasis PRiME HLB cartridges. The matrix effect was effectively eliminated after the clean-up procedure as confirmed by comparing the ratio of standard curves prepared by standards dissolved in both matrix solvent and 5 mmol/L ammonium acetate in water: acetonitrile (95:5, v/v). The recoveries of these nitrofuran metabolites under the 1 µg/kg, 2 µg/kg and 10 µg/kg spiking levels were between 77.4% and 95.6%. These metabolites after the extraction were stable at 4 °C for 24 h. The validated method was used to analyze the residue level of these nitrofuran metabolites in 25 gelatin Chinese medicines. Results showed that only one Colla Corii Asini sample contained SEM (2.52 µg/kg) and AOZ (6.27 µg/kg), whereas one Testudinis Carapacis et Plastri sample had SEM (1.27 µg/kg) and AMOZ (9.53 µg/kg).

Multi-residue analysis of captan, captafol, folpet, and iprodione in cereals using liquid chromatography with tandem mass spectrometry.

In this study, we propose an improved analytical method for the multiresidue analysis of captan (plus its metabolite, tetrahydrophthalimide), folpet (plus its metabolite, phthalimide), captafol, and iprodione in cereals using liquid chromatography tandem mass spectrometry (LC-MS/MS). As captan, captafol, and folpet are easily degraded during homogenisation and extraction, samples were comminuted with liquid nitrogen, and both QuEChERS and ethyl acetate-based extraction workflows provided a satisfactory method performance. The optimised LC-MS/MS procedure with electrospray ionisation did not degrade these compounds, and offered sufficient method selectivity by resolving and minimising co-eluting matrix-derived interferences. The method also resolved the problem of non-specific mass spectra that these compounds usually produce on GC-MS analysis involving electron ionisation. The method performance was satisfactory for all 6 compounds at 0.01 mg kg-1 and higher levels of fortification, and validated as per the SANTE/11813/2017 guidelines of analytical quality control in a wide range of cereals including rice, wheat, sorghum, and corn. The method provides special advantage of simultaneous analysis of captan, and folpet along with their metabolites (tetrahydrophthalimide, and phthalimide, respectively) in combination with captafol, and iprodione in a single chromatographic run. Although iprodione is known to degrade to 3,5-dichloroaniline, since this metabolite is not a part of the residue definition, it was not included in the scope of this method. As the method demonstrates satisfactory selectivity, sensitivity, accuracy, precision, and robustness in a wide range of cereal matrices, it is recommended for regulatory testing of these compounds in cereals.

Molecularly imprinted sol-gel polymers for the analysis of iprodione fungicide in wine: Synthesis in green solvent.

Iprodione is a fungicide widely used in viticulture in most agricultural countries. It was banned recently in the European community because of its carcinogenic and endocrine disrupting characters. In this work, a cheap analytical method able to monitor iprodione in a white wine was developed. Molecularly imprinted sol-gel polymers (MIS) specific to iprodione and using green solvents were synthesized. An experimental design having the following factors (solvent volume and crosslinker quantity) was used to prepare an optimal MIS. In terms of selectivity, the optimal MIS showed the best partition coefficient towards iprodione in a white wine containing four other competing fungicides (procymidone, pyrimethanil, azoxystrobin and iprovalicarb). A solid phase extraction method using the optimal MIS was optimized and applied to analyse iprodione in a white wine. Low detection and quantification limits were reached 11.7 and 39.1 µg/L respectively.

Improved analysis of captan, tetrahydrophthalimide, captafol, folpet, phthalimide, and iprodione in fruits and vegetables by liquid chromatography tandem mass spectrometry.

An improved liquid chromatography tandem mass spectrometry method is reported for the determination of residues of captan (+tetrahydrophthalimide), captafol, folpet (+phthalimide), and iprodione in fruits and vegetables. The optimized electrospray ionization parameters (high cone gas flow, and a low desolvation temperature) did not result in degradation of target compounds, rather they provided a significant advantage over the conventional GC-MS/MS methods, which lack sensitivity and repeatability. Strategies for minimizing losses in recovery of these compounds during sample preparation included cryogenic comminution, extraction with acidified ethyl acetate or acetonitrile, and dilution of the final extract with acidified water prior to LC-MS/MS analysis. The method performance complied with the SANTE/11813/2017 guidelines, with recoveries in the range of 70-120% at the LOQ of 0.01 mg/kg across the tested matrices at various pHs. The efficiency of the method was reflected in its precision (RSDs < 10%) for incurred residues.

Mass spectrometry of hydantoin-derived selective androgen receptor modulators.

N-Aryl-hydroxybicyclohydantoins represent a new class of tissue-selective anabolic agents [selective androgen receptor modulators (SARMs)] and are promising therapeutics as well as drugs prohibited in amateur and professional sport. The dissociation behavior after negative and positive electrospray ionization (ESI) and subsequent collision-induced dissociation (CID) was studied with a drug candidate (BMS 564929) as well as structurally related and isotope-labeled analogs using high resolution/high accuracy orbitrap mass spectrometry. Positive ionization and CID yielded characteristic product ions resulting from the cleavage of the hydantoin structure providing information about the proline-derived nucleus as well as the substituted aryl residue at m/z 96 and 193, respectively. Negative ESI and CID (MS/MS) yielded product ions mainly representing losses of water and CO(2), the latter of which is of particular significance as the hydantoin structure does not contain a carboxyl function. Employing MS(n) experiments with accurate mass determination on six model SARMs, dissociation pathways to characteristic product ions were proposed supporting the identification of these drugs, their metabolites or related compounds in future doping control assays.

Rapid analysis of multiple pesticide residues in fruit-based baby food using programmed temperature vaporiser injection-low-pressure gas chromatography-high-resolution time-of-flight mass spectrometry.

A rapid method using programmed temperature vaporiser injection-low-pressure gas chromatography-high-resolution time-of-flight mass spectrometry (PTV-LP-GC-HR-TOF-MS) for the analysis of multiple pesticide residues in fruit-based baby food was developed. The fast and inexpensive buffered QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction method and "conventional" approach that employs ethyl acetate extraction followed by gel permeation chromatography (GPC) cleanup were employed for sample preparation. A PTV injector in solvent venting mode was used to reduce volume of acetonitrile and acetic acid (from the buffered QuEChERS extracts) that caused higher column bleed without their elimination. Otherwise, the time-to-digital converter would become saturated in HR-TOF-MS. For fast GC separation allowing analysis of 100 analytes within a 7 min runtime, both a high temperature programming rate and vacuum conditions in a megabore GC column were employed. The use of HR-TOF-MS allowed the unbiased identification and reliable quantification of target analytes through the application of a narrow mass window (0.02 Da) for extracting analyte ions and the availability of full spectral information even at very low levels. With only a few exceptions, the lowest calibration levels for the pesticides tested were