Thiabendazole Research Articles

Supported liquid membrane-protected molecularly imprinted fibre for solid-phase microextraction of thiabendazole

In this work, molecularly imprinted polymer fibres (MIP-fibre) have been prepared and evaluated for solid-phase microextraction (SPME), using thiabendazole (TBZ) as template. Inherent limitations of molecular imprinted polymers, such as target recognition in aqueous media, have been solved with the use of organic supported liquid membrane (SLM) protecting the MI-SPME process. MIP-fibres were located inside a polypropylene hollow capillary and protected by an organic solvent immobilized as a thin SLM in the pores of the capillary wall. The extraction procedure involved two simultaneous processes: liquid phase microextraction using polypropylene hollow fibres (HF-LPME) of the analytes from the sample to an organic acceptor solution through a SLM; and SPME of the analytes from the organic acceptor solution to a MIP-fibre inside the polypropylene capillary. The developed methodology was optimized and applied to the extraction of TBZ form spiked orange juices. Calibration curves showed good linearity in the concentration range under study (0.01–5.00 mg L −1) and a regression coefficient better than 0.995 was obtained. The detection limit was 4 μg L −1, low enough to permit the satisfactory analysis of TBZ in real samples, according to European regulation. Relative standard deviations ranged below 10%, indicating good repeatability. By this manner, the advantages of inherent selectivity of MIP SPME fibres and the enrichment and sample cleanup capability of the HF-LPME have been successfully combined into a single device.

First Report of in vitro Fludioxonil-Resistant Isolates of Fusarium spp. Causing Potato Dry Rot in Michigan.

Fusarium dry rot of potato (Solanum tuberosum) is a postharvest disease caused by several Fusarium spp. Dry rot is managed primarily by reducing tuber bruising and promoting rapid wound healing. Dry rot symptomatic tubers were collected from Michigan seed lots in 2009 and 2010. The isolates may not have been exposed to fludioxonil because currently applications are restricted to seed not intended for seed production (3). Small sections were cut from the margins of necrotic regions with a scalpel, surface sterile in 10% sodium hypochlorite for 10 s, rinsed twice in sterile distilled water, and blotted with sterile filter paper. The tissue pieces were plated on half-strength potato dextrose agar (PDA) amended with 0.5 g/liter of streptomycin sulfate. The dishes were incubated at 23°C for 5 to 7 days. Cultures resembling Fusarium spp. were transferred onto water agar and hyphal tips from the margin of actively growing isolates were removed with a sterile probe and plated either on carnation leaf agar (CLA) or on half-strength PDA to generate pure cultures. Fusarium isolates were obtained and used for further studies. Among them, 54 were identified as Fusarium oxysporum and 23 as F. sambucinum. Identification was based on colony and conidial morphology on PDA and CLA, respectively. The identity was confirmed through DNA extraction followed by amplification and sequencing of the translation elongation factor (EF-1α) gene region. The Fusarium-ID v. (2) and the NCBI database were used to obtain the closest match to previously sequenced materials. Pathogenicity testing was done on disease-free potato tubers, cv. FL 1879. Tubers were surface sterilized for 10 min in 10% sodium hypochlorite and rinsed twice in distilled water. Three tubers per isolate were injected with 20 μl of a conidial suspension (106 conidia/ml) made from cultures grown on PDA for 7 days. Control tubers were injected with 20 μl of sterile distilled water. All tubers inoculated with F. sambucinum and F. oxysporum developed typical potato dry rot symptoms consisting of dry brown decay lesions. F. sambucinum and F. oxysporum were reisolated from all symptomatic tubers. An effective concentration for 50% reduction in growth (EC50) was determined for each F. sambucinum and F. oxysporum isolate for thiabendazole (TBZ), fludioxonil, and difenoconazole using the spiral gradient endpoint method (1). Sensitive and resistant F. sambucinum and F. oxysporum isolates were reported. Fifteen isolates of F. sambucinum and thirty-four of F. oxysporum were resistant to fludioxonil with EC50 greater than 130 mg/liter. The remainder was sensitive to fludioxonil with EC50 ranging from 0.8 to 4.9 mg/liter. To our knowledge, this is the first report of resistance to fludioxonil in isolates of F. sambucinum and F. oxysporum in Michigan. Fusarium insensitivity in laboratory studies may not translate directly to commercial production. This disparity may result from interactions not experienced in mixed populations or within a living host. There has been no compelling evidence to suggest that fludioxonil has failed to perform because of insensitivity to Fusarium. The occurrence of such isolated strains necessitates the development and registration of partner chemistries that can preempt any future concerns on lack of performance of products in use.

Supramolecular encapsulation of benzimidazole-derived drugs by cucurbit[7]uril

UV–vis and NMR spectroscopic techniques were employed to demonstrate the ability of the synthetic macrocyclic host cucurbit[7]uril (CB7) to solubilize and stabilize widely used fungicides and anthelmintic drugs of the benzimidazole family in water, namely, albendazole (ABZ), carbendazim (CBZ), thiabendazole (TBZ), fuberidazole (FBZ), and the parent benzimidazole (BZ). CB7 binds the protonated forms of these guests very strongly (e.g., K = 2.6 × 107 L/mol for ABZ) but their neutral forms significantly more weakly (e.g., K = 6.5 × 104 L/mol for ABZ), which reflects a complexation-induced increase of their pKa values by 2.6 units for ABZ, 2.5 units for CBZ, 4.0 units for TBZ, 3.8 units for FBZ, and 3.5 units for BZ. The absolute drug solubilities increased upon complexation from 0.003 to 0.300 mmol/L for ABZ, from 0.160 to 1.12 mmol/L for CBZ, from 0.110 to 1.11 mmol/L for TBZ, and from 0.25 to 0.75 mmol/L for FBZ (for BZ, the solubility enhancement was found to be insignificant). Complexation by CB7 further improves the photostability of the drugs and alters their photophysical properties.

Fission Yeast Pot1 and RecQ Helicase Are Required for Efficient Chromosome Segregation

Pot1 is a single-stranded telomere-binding protein that is conserved from fission yeast to mammals. Deletion of Schizosaccharomyces pombe pot1(+) causes immediate telomere loss. S. pombe Rqh1 is a homolog of the human RecQ helicase WRN, which plays essential roles in the maintenance of genomic stability. Here, we demonstrate that a pot1Δ rqh1-hd (helicase-dead) double mutant maintains telomeres that are dependent on Rad51-mediated homologous recombination. Interestingly, the pot1Δ rqh1-hd double mutant displays a "cut" (cell untimely torn) phenotype and is sensitive to the antimicrotubule drug thiabendazole (TBZ). Moreover, the chromosome ends of the double mutant do not enter the pulsed-field electrophoresis gel. These results suggest that the entangled chromosome ends in the pot1Δ rqh1-hd double mutant inhibit chromosome segregation, signifying that Pot1 and Rqh1 are required for efficient chromosome segregation. We also found that POT1 knockdown, WRN-deficient human cells are sensitive to the antimicrotubule drug vinblastine, implying that some of the functions of S. pombe Pot1 and Rqh1 may be conserved in their respective human counterparts POT1 and WRN.

Integrated control of blue mould using new fungicides and biocontrol yeasts lowers levels of fungicide residues and patulin contamination in apples

We tested the compatibility of the biocontrol yeasts (Rhodosporidium kratochvilovae LS11 and Cryptococcus laurentii LS28) with the recently developed fungicides boscalid (BOSC), cyprodinil (CYPR) and fenhexamid (FENH) to create an efficient integrated approach to control blue mould on apples. The fungicide thiabendazole (TBZ), which is presently allowed for postharvest treatment of pome fruit in different countries, was also used as the control. Both the biocontrol agents (BCAs) LS11 and LS28 were compatible in vitro with BOSC and CYPR, whereas they were strongly inhibited by FENH. TBZ was compatible with LS28, while it strongly inhibited LS11. In vitro assays with some isolates of Penicillium expansum showed that the majority were resistant to TBZ, whereas they were all markedly inhibited by BOSC and CYPR. Experiments of integrated control were performed on wounded apples kept at 21°C up to 7 days. After 4 days of storage, the combination of a low BCA concentration (5×106cfumL−1) with a low dose (25% of the label dose) of commercial formulates of BOSC or CYPR, resulted in an efficient reduction of blue mould incidence (83–100% less infection with respect to the control). Conversely, the combination of BCAs with TBZ was less effective (not more than 60% of rot reduction). When applied alone at low dosage, LS11, LS28, BOSC, CYPR and TBZ reduced Penicillium rot by 35%, 52%, 67%, 72% and 0%, respectively. After 7 days of storage, only the integrated treatment based on BCAs with BOSC or CYPR resulted in a significant rot reduction (as much as 98%). Treatments based on the utilization of the BCA LS28 or low dosage of CYPR alone were much less effective (10% and 28% rot reduction, respectively), whereas both BCAs integrated with TBZ were ineffective. Furthermore, integrated treatments (BCAs+BOSC or CYPR) resulted in lower fungicide residues and patulin (PAT) contamination in apples. Our data show that the integration of biocontrol yeasts with a low rate of the recently commercialized fungicides BOSC or CYPR could be an effective and safer strategy to control P. expansum and keep fungicide residues as well as PAT contamination in apples low.

Study on Analytical Method for Thiabendazole in Toasted and Seasoned Laver by LC-MS/MS

Thiabendazole (TBZ), a pesticide with antifungal activity, was detected in toasted and seasoned laver which had been reported as tasting unpleasant by consumers in March 2008. From a survey of the manufacturing process, it was concluded that the TBZ contamination had originated from a sponge-roller which was used to paste seasoned liquid onto the toasted laver. At that time it was found that TBZ is widely used to prevent fungal contamination of sponge-rollers. For further survey of TBZ contamination in the laver, we developed a more sensitive detection method using LC-MS/MS. With our new method, six commercial products harvested in March 2008 and July 2009, respectively, were tested. Five out of six samples harvested in 2008 were positive for TBZ, with values in the range from 0.014 to 1.736 µg/g. Only one sample harvested in 2009 contained a detectable level of TBZ. The data obtained here contributed to the improvement of the manufacturing process.

Synthesis of core‐shell molecularly imprinted polymer microspheres by precipitation polymerization for the inline molecularly imprinted solid‐phase extraction of thiabendazole from citrus fruits and orange juice samples

In this work, the synthesis of molecularly imprinted polymer microspheres with narrow particle size distributions and core-shell morphology by a two-step precipitation polymerization procedure is described. Polydivinylbenzene (poly DVB-80) core particles were used as seed particles in the production of molecularly imprinted polymer shells by copolymerization of divinylbenzene-80 with methacrylic acid in the presence of thiabendazole (TBZ) and an appropriate porogen. Thereafter, polymer particles were packed into refillable stainless steel HPLC columns used in the development of an inline molecularly imprinted SPE method for the determination of TBZ in citrus fruits and orange juice samples. Under optimized chromatographic conditions, recoveries of TBZ within the range 81.1-106.4%, depending upon the sample, were obtained, with RSDs lower than 10%. This novel method permits the unequivocal determination of TBZ in the samples under study, according to the maximum residue levels allowed within Europe, in less than 20 min and without any need for a clean-up step in the analytical protocol.

The effects of flubendazole and its metabolites on the larval development of Haemonchus contortus (Nematoda: Trichostrongylidae): an in vitro study

Abstract The anthelmintic effects of flubendazole (FLU), its two main metabolites reduced flubendazole (FLU-R) and hydrolyzed flubendazole (FLU-H), and thiabendazole (TBZ) were compared using an in vitro larval development test in two isolates of Haemonchus contortus, a fully susceptible isolate (HCS) and a multi-resistant isolate (HCR). Results were quantified as 50 % lethal concentration (LC50), 99 % lethal concentration (LC99), efficacy factor (EF), and resistance factor (RF). For HCS, both LC50 and LC99 of FLU were lower than those of the reference TBZ. The anthelmintic activity of FLU-R in HCS and HCR was 13 and 6 times lower than the activity of FLU, respectively. The anthelmintic activity of FLU-H was negligible (approximately 363–853 times lower) compared to that of FLU. Although a marked resistance of the HCR isolate to TBZ was confirmed, only a low tolerance to FLU-R and slightly higher tolerance to FLU were found.

THE EFFECTS OF SOME NEW POSTHARVEST FUNGICIDES AND COMBINATION OF HOT WATER WITH SODIUM BICARBONATE AGAINST GEOTRICHUM CITRI-AURANTII ON CITRUS

Geotrichum citri-auranti, sour rot of citrus, causes economical crop losses on Satsuma mandarin and lemon in Turkey. Because the usage of guazatine was restricted in packinghouses, new solutions are required to minimize these pathogens. Thirty-two isolates of G. citri-auranti were collected from packinghouses in Ege and the Mediterranean Region and tested against fungicides. In this project, we examined the old postharvest fungicides; guazatine, thiabendazole (TBZ) and imazalil against G. citri-auranti and new generation postharvest fungicides such as pyrimethanil, fludioxonil and azoxystrobin at different doses in vitro and in vivo. We also studied sensitivity of pathogen isolates against fungicides in vitro. All of the isolates were found resistant to imazalil and TBZ even high doses of fungicides. It was found that 28% of isolates were sensitive to guazatine and 72% resistant. Both in vitro and in vivo tested azoxystrobin did not affect pathogen growth and decay development. Only guazatine was effective on pathogens growth and decay development. In vivo tests conducted on Satsuma mandarin showed that a combination of sodium bicarbonate (2%) and guazatine (900 μg/ml) and their combination were the most effective treatments for disease development.

Potential for bioremediation of agro-industrial effluents with high loads of pesticides by selected fungi

Wastewaters from the fruit packaging industry contain a high pesticide load and require treatment before their environmental discharge. We provide first evidence for the potential bioremediation of these wastewaters. Three white rot fungi (WRF) (Phanerochaete chrysosporium, Trametes versicolor, Pleurotus ostreatus) and an Aspergillus niger strain were tested in straw extract medium (StEM) and soil extract medium (SEM) for degrading the pesticides thiabendazole (TBZ), imazalil (IMZ), thiophanate methyl (TM), ortho-phenylphenol (OPP), diphenylamine (DPA) and chlorpyrifos (CHL). Peroxidase (LiP, MnP) and laccase (Lac) activity was also determined to investigate their involvement in pesticide degradation. T. versicolor and P. ostreatus were the most efficient degraders and degraded all pesticides (10 mg l⁻¹) except TBZ, with maximum efficiency in StEM. The phenolic pesticides OPP and DPA were rapidly degraded by these two fungi with a concurrent increase in MnP and Lac activity. In contrast, these enzymes were not associated with the degradation of CHL, IMZ and TM implying the involvement of other enzymes. T. versicolor degraded spillage-level pesticide concentrations (50 mg l⁻¹) either fully (DPA, OPP) or partially (TBZ, IMZ). The fungus was also able to rapidly degrade a mixture of TM/DPA (50 mg l⁻¹), whereas it failed to degrade IMZ and TBZ when supplied in a mixture with OPP. Overall, T. versicolor and P. ostreatus showed great potential for the bioremediation of wastewaters from the fruit packaging industry. However, degradation of TBZ should be also achieved before further scaling up.

Larval papulonodular dermatitis treated with topical tiabendazole

Larval papulonodular dermatitis treated with topical tiabendazole

Lc/Esi/Ms/Ms determination of postharvest fungicide residues in citrus juices

An LC-ESI-MS/MS method was developed for the quantitative detection of postharvest fungicide residues in citrus juices and reported in this paper. The analyses of thiabendazole (TBZ), carbendazim (MBC), thiophanate methyl (TPM), imazalil (IMZ) and prochloraz (PCZ) residues were performed by using a gradient elution in conjunction with positive ionization mode electrospray ionization tandem mass spectrometry. Fungicides were extracted from citrus juices with recoveries ranging from 79.8 to 101.2% and relative standard deviation better than 15%. The quantification limits ranged from 0.01 μg/kg IMZ to 0.06 μg/kg for MBC. The LC-MS-MS method was applied to commercial citrus juices, detecting MBC, TBZ and IMZ residues in the 90% of the samples. Prochloraz residues were detected only in one of the multifruit juice (orange, lemon and carrot) samples.

Hollow fiber-liquid-phase microextraction of fungicides from orange juices

Liquid-phase microextraction (LPME) based on polypropylene hollow fibers was evaluated for the extraction of the post-harvest fungicides thiabendazole (TBZ), carbendazim (CBZ) and imazalil (IMZ) from orange juices. Direct LPME was performed without any sample pretreatment prior to the extraction, using a simple home-built equipment. A volume of 500 μL of 840 mM NaOH was added to 3 mL of orange juice in order to compensate the acidity of the samples and to adjust pH into the alkaline region. Analytes were extracted in their neutral state through a supported liquid membrane (SLM) of 2-octanone into 20 μL of a stagnant aqueous solution of 10 mM HCl inside the lumen of the hollow fiber. Subsequently, the acceptor solution was directly subjected to analysis. Capillary electrophoresis (CE) was used during the optimization of the extraction procedure. Working under the optimized extraction conditions, LPME effectively extracted the analytes from different orange juices, regardless of different pH or solid material (pulp) present in the sample, with recoveries that ranged between 17.0 and 33.7%. The analytical performance of the method was evaluated by liquid chromatography coupled with mass spectrometry (LC/MS). This technique provided better sensitivity than CE and permitted the detection below the μg L −1 level. The relative standard deviations of the recoveries (RSDs) ranged between 3.4 and 10.6%, which are acceptable values for a manual microextraction technique without any previous sample treatment, using a home-built equipment and working under non-equilibrium conditions (30 min extraction). Linearity was obtained in the range 0.1–10.0 μg L −1, with r = 0.999 and 0.998 for TBZ and IMZ, respectively. Limits of detection were below 0.1 μg L −1 and are consistent with the maximum residue levels permitted for pesticides in drinking water, which is the most restrictive regulation applicable for these kinds of samples. It has been demonstrated the suitability of three-phase LPME for the extraction of pesticides from citrus juices, suppressing any pretreatment step such as filtration or removal of the solid material from the sample, that may potentially involve a loss of analyte.

Adaptation and evaluation of three different in vitro tests for the detection of resistance to anthelmintics in gastro intestinal nematodes of cattle

Three different in vitro methods, the Larval Development Test (LDT), the Larval Migration Inhibition Test (LMIT) and the Micromotility Meter Test (MMT) have been adapted to detect anthelmintic resistance in cattle nematodes. Nematode eggs and third stage larvae of different Ostertagia ostertagi and Cooperia oncophora isolates were obtained from faecal cultures of experimentally infected calves. Additionally, adult C. oncophora were evaluated in the MMT for the detection of resistance to ivermectin (IVM). For all three in vitro tests standard operating procedures (SOPs) were established and successfully used for the detection of responses of non-parasitic and parasitic stages to different anthelmintic substances and the description of dose–response curves. In the LDT ivermectin (IVM) and thiabendazole (TBZ) were tested, in the LMIT IVM and levamisole (LEV) and in the MMT only IVM was evaluated. Susceptible isolates of C. oncophora and O. ostertagi, an IVM-resistant isolate of C. oncophora and a TBZ-selected isolate of O. ostertagi were used in all ( C. oncophora) or only some of these tests ( O. ostertagi). For all isolates sigmoidal dose–response curves and EC 50 values for the tested substances were obtained using a four-parameter logistic model. For the LDT, the previously reported problem in development of larvae was successfully overcome with mean development rates between 80% and 87% in negative controls. Following optimization of incubation times, temperatures, mesh sizes (LMIT only), nutritive medium (LDT only) and group size (MMT only) all three test systems reliably detected significant differences in the response to IVM between the susceptible and IVM-resistant isolate of C. oncophora ( p < 0.0001), resulting in an resistance ratio (RR) value of approximately 5 for IVM and 2.8 for LEV in C. oncophora. The LDT also detected differences in the response to TBZ between the susceptible and BZ-selected O. ostertagi isolates ( p < 0.001) with an RR of 2 for TBZ. With the standardization of the described tests we report reproducible and reliable in vitro methods for the detection of resistance to IVM (LDT, LMIT and MMT) and TBZ (LDT) for cattle parasitic nematodes.

Chromatographic performance of molecularly imprinted polymers: Core‐shell microspheres by precipitation polymerization and grafted MIP films via iniferter‐modified silica beads

AbstractIn this work, two different surface imprinting formats have been evaluated using thiabendazole (TBZ) as model template. The first format is a thin film of molecularly imprinted polymer (MIP) grafted from preformed silica particles using an immobilized iniferter‐type initiator (inif‐MIP). The second format is molecularly imprinted polymer microspheres with narrow particle size distribution and core‐shell morphology prepared by precipitation polymerization in a two‐step procedure. For the latter format, polymer microspheres (the core particles) were obtained by precipitation polymerization of divinylbenzene‐80 (DVB‐80) in acetonitrile. Thereafter, the core particles were used as seed particles in the synthesis of MIP shells by copolymerization of DVB‐80 and methacrylic acid in the presence of TBZ in a mixed solvent porogen (acetonitrile/toluene). The materials were characterized by elemental microanalysis, nitrogen sorption porosimetry and scanning (and transmission) electron microscopy. Thereafter, the imprinted materials were assessed as stationary phases in liquid chromatography. From this study it can be concluded that grafted MIP beads can be obtained in a simple and direct manner, consuming only a fraction of the reagents used typically to prepare imprinted particles from a monolithic imprinted polymer. Such materials can be used in the development of in‐line molecularly imprinted solid‐phase extraction methods. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1058–1066, 2010

Surface-enhanced Raman Spectroscopy of Benzimidazolic Fungicides: Benzimidazole and Thiabendazole

Surface-enhanced Raman Scattering (SERS) spectroscopy is applied to the study of the adsorption of benzoimidazolic fungicides benzimidazole (BIZ) and thiabendazole (TBZ) on silver mirrors. The influence of pH on the adsorption mechanism was investigated. In case of BIZ, two different adsorption mechanisms are deduced depending on the experimental conditions: via the <TEX>$\pi$</TEX> electrons of the ring in neutral conditions and through an ionic pairing of protonated nitrogen atom with the chloride adsorbed on the metal surface. The SERS spectra of TBZ revealed that most molecules were adsorbed on silver surface by the <TEX>${\pi}$</TEX> electrons in neutral and acidic conditions but in acid conditions, some molecules were adsorbed via the sulfur and nitrogen atoms tilted slightly to the surface.

Profiling of compounds and degradation products from the postharvest treatment of pears and apples by ultra-high pressure liquid chromatography quadrupole-time-of-flight mass spectrometry

This study deals with a simple strategy to pinpoint potential unknown compounds in full scan mass spectrometry (MS) experiments. Forty samples of apples and pears intended for human consumption were analyzed by ultra-high performance liquid chromatography quadrupole-time-of-flight (UPLC-QqTOF-MS), after extraction of the possible contaminants by rinsing the peel of the fruit with ethyl acetate. The peaks were visually recognized in the total ion chromatogram (TIC). Two major types of postharvest treatments were detected in this set of samples: imazalil (IMZ)/ethoxyquin (EQ) and thiabendazole (TBZ)/diphenylamine (DPA). The present work also describes the metabolites formed by degradation of EQ (to our knowledge not previously reported) and DPA (there was mass spectral evidence of some of them but full identification was not pursued). Hydroxy-DPA, n-phenyl-4-quinoneimine, methoxy-DPA, demethyl-EQ, demethyldehydro-EQ, EQ-dimer, methyl-EQ, EQ-N-oxyl and 2',2,4,-trimethyl-6-quinolone were unequivocally identified and confirmed. Some relationships between the applied postharvest treatment and the metabolites formed were established. Remarkably, they may constitute a useful fingerprint in further investigations of postharvest treatments. Among other significant results, the study also reveals for the first time the presence of some EQ metabolites in fruits, which are different from those previously reported in animal tissues. There is not information on the occurrence of EQ metabolites in fruits and the DPA ones have not been studied extensively in pears and apples. The levels of the metabolites found exceeded several times those of the parent compounds.

신고배 저장중 과피얼룩 및 부패병에 대한 방제 효과

Postharvest skin sooty dapple and decay disease of pear fruit often originates at small stain symptoms that occurred during harvest and handling. Experiments were conducted to characterize the effect of timing of application of disease control materials, and to evaluate sequential postharvest applications of fungicides or fungicides and bio-control agents. Fungicides and bio-control agents were increasingly less effective when the period between harvest and application was prolonged. Thiabendazole (TBZ) applied to fruit without artificial wounding or inoculation effectively reduced skin sooty and decay disease when applied within 3 weeks or 6 weeks in 2 years of study. TBZ, Fludioxonil and pyrimethanil were effective in controlling skin sooty and decay disease at artificial wounds inoculated with Cladosporium tenuissimum up to 14 days after inoculation. Application of TBZ at harvest followed 3 weeks later by application of Fludioxonil was superior to application of TBZ at harvest alone. Two bacterial biocontrol agents reduced skin sooty and decay disease at pear wounds inoculated with C. tenuissimum up to 14 days after inoculation with C. tenuissimum, but were ineffective when applied at 28 days after inoculation. Of possible sequential arrangements of fungicide and bio-control treatments, application of the most effective material promptly after harvest generally resulted in the highest level of disease control.

Determination of benzimidazolic fungicides in fruits and vegetables by supramolecular solvent-based microextraction/liquid chromatography/fluorescence detection

A supramolecular solvent consisting of vesicles, made up of equimolecular amounts of decanoic acid (DeA) and tetrabutylammonium decanoate (Bu 4NDe), dispersed in a continuous aqueous phase, is proposed for the extraction of benzimidazolic fungicides (BFs) from fruits and vegetables. Carbendazim (CB), thiabendazole (TB) and fuberidazole (FB) were extracted in a single step and no clean-up or concentration of extracts was needed. The high extraction efficiency obtained for BFs was a result of the different types of interactions provided by the supramolecular solvent (e.g. hydrophobic and hydrogen bonds) and the high number of solubilisation sites it contains. Besides simple and efficient, the proposed extraction approach was rapid, low-cost, environment friendly and it was implemented using conventional lab equipments. The target analytes were determined in the supramolecular extract by LC/fluorescence detection. They were separated in a Kromasil C 18 (5 μm, 150 mm × 4.6 mm) column using isocratic elution [mobile phase: 60:40 (v/v) 50 mM phosphate buffer (pH 4)/methanol] and quantified at 286/320 nm (CB) and 300/350 nm (TB and FB) excitation/emission wavelengths, respectively. Quantitation limits provided by the supramolecular solvent-based microextraction (SUSME)/LC/fluorescence detection proposed method for the determination of CB, TB and FB in fruits and vegetables were 14.0, 1.3 and 0.03 μg kg −1, respectively, values far below the current maximum residue levels (MRLs) established by the European Union, i.e. 100–2000 μg kg −1 for CB, 50–5000 μg kg −1 for TB and 50 μg kg −1 for FB. The precision of the method, expressed as relative standard deviation, for inter-day measurements ( n = 13) was 3.3% for CB (50 μg kg −1), 3.5% for TB (10 μg kg −1) and 2.8% for FB (0.5 μg kg −1) and recoveries for fruits (oranges, tangerines, lemons, limes, grapefruits, apples, pears and bananas) and vegetables (potatoes and lettuces) fortified at the μg kg −1 level were in the interval 93–102%.

Simultaneous Flow-Injection Solid-Phase Fluorometric Determination of Thiabendazole and Metsulfuron Methyl Using Photochemical Derivatization

A flow-through optosensor implemented with photochemically induced fluorescence (PIF) is reported for the simultaneous determination of thiabendazole (TBZ) and metsulfuron methyl (MET). TBZ is determined by measuring its native fluorescence once retained on the solid support filling the flow-cell of a FI-system. On the other hand, a strongly fluorescent photoproduct from MET is generated on-line in micellar medium by UV irradiation and monitored in a similar way to TBZ. MET photoproduct and TBZ are separated by placing in the flow-system a minicolumn, filled with C(18) silica gel, which allows their sequential arrival to the detection area. The sorption of the species on the solid support in the detection area provides a noticeable improvement in sensitivity and selectivity when comparing with their determination in homogeneous solution. The detection limits and RSDs for TBZ and MET are 2.5 and 3.3 ng ml(-1) and 1.1 and 2.4%, respectively. The method is successfully applied to environmental water samples.