Thiabendazole Research Articles

Determination of 5-hydroxythiabendazole in human urine as a biomarker of exposure to thiabendazole using LC/MS/MS.

Thiabendazole (TBZ) is widely used as a pre-planting and post-harvest agricultural fungicide and as an anthelminthic in humans and animals. TBZ is of toxicological concern, since adverse effects including nephrogenic, hepatogenic, teratogenic and neurological effects have been reported in mammals. Occupational exposure can occur among agricultural workers and the general public may be environmentally exposed to TBZ through the diet. The metabolite 5-hydroxythiabendazole (5-OH-TBZ) was chosen as biomarker of exposure to TBZ and a LC/MS/MS method for the quantification of 5-OH-TBZ in human urine was developed. The method includes enzyme hydrolysis, as 5-OH-TBZ is conjugated to glucuronide and sulphate in urine. Sample through put was optimised using 96-well plates for sample handling as well as for solid phase extraction (SPE). The method has excellent, within-run, between-run and between-batch precision between 4 and 9%. The limit of detection (LOD) of 0.05 and a limit of quantification (LOQ) of 0.13ng 5-OH-TBZ/mL urine enable detection in environmentally exposed populations. When applying the method in a general Swedish population, 52% had levels above LOD. The method was also applied in one oral and one dermal human experimental exposure study in two individuals. After oral exposure, the excretion of 5-OH-TBZ in urine was described by a two-compartment model and both the first rapid and the second slower elimination phase followed first-order kinetics, with estimated elimination half-life of 2h and 9-12h. The recoveries in urine were between 21 and 24% of the dose. Dermal exposure was described by a one compartment model and followed first order kinetics, with estimated elimination half-life of 9-18h. The recovery in urine was 1% of the administrated dose of TBZ. Although these studies are limited to two individuals, the data provide new basic information regarding the toxicokinetics of TBZ after oral and dermal exposure.

Modelling of the operation of raceway pond reactors for micropollutant removal by solar photo-Fenton as a function of photon absorption

Raceway ponds reactors (RPRs) are extensive non-concentrating photoreactors which allow large volumes of water to be treated. They consist of channels where water is set in motion by a paddlewheel system. In this work the effect of solar irradiance on RPR operation to remove micropollutants by solar photo-Fenton was studied. A RPR was used at pilot plant scale (up to 360L) and the pesticides acetamiprid (ACTM) and thiabendazole (TBZ) were used as a model pollutant mixture (100μg/L each) in simulated effluent. Averaged UV irradiances ranged from 10 to 30W/m2 and three values of iron concentration (1, 5.5 and 10mg/L) were used. Different liquid depths were also used to evaluate the relationship between the rate of photon absorption and pollutant removal. A model was proposed to predict degradation rate and treatment capacity as a function of the volumetric rate of photon absorption (VRPA). Under low irradiance conditions (10W/m2) the treatment capacity was not sensitive above 10cm liquid depth, so a low iron concentration should be used (5mg Fe/L). For high irradiance values (30W/m2), greater liquid depth (20cm) and iron concentration (10mg Fe/L) should be used to take full advantage of photon availability. Treatment capacity values of 133mg/hm2 can be reached under these conditions.

Reduction of benzimidazole resistance in established Haemonchus contortus populations in goats using a single infection with a benzimidazole-susceptible isolate.

An in vivo study in goats evaluated the effect of superimposing a single artificial infection with a benzimidazole (BZ)-susceptible Haemonchus contortus isolate upon established H. contortus populations of known BZ resistance by measuring the phenotypic BZ resistance of eggs collected from faeces before and after re-infection. Two H. contortus isolates, one benzimidazole resistant (BZR) and the other susceptible (BZS), were used to infect worm-free goats. Eight goats were initially infected with 2000 third-stage larvae (L3). In each case the inoculum contained a pre-determined proportion of the two isolates: 100% BZS (one goat), 75% BZS/25% BZR (two goats), 50% BZS/50% BZR (two goats), 25%BZS/75% BZR (two goats) and, finally, 100% BZR (one goat). The phenotypic BZ susceptibility of the H. contortus population formed in each goat after the first infection was determined on days 30 and 36 post-infection using an egg-hatch assay (EHA) that estimated the concentration of thiabendazole (TBZ) required for 95% inhibition of larval hatching (EC(95)) with a 95% confidence interval (95% CI). On day 49 post-infection, goats were re-infected with 2000 L3 of the BZS isolate alone. A second set of EHA bioassays was performed 28 days and 34 days after re-infection. The first infection protocol produced three populations classified as BZS (EC(95) 0.055-0.065 μg TBZ/ml) while four were categorized as BZR (EC(95) 0.122-0.344 μg TBZ/ml). The status of one other population could not be determined. After re-infection with BZS L3, the number of susceptible populations increased to six (EC(95) 0.043-0.074 μg TBZ/ml) while the remaining two were deemed resistant (EC(95) 0.114-119 μg TBZ/ml). Re-infection with BZS L3 thereby reduced the resistance status of most H. contortus populations.

New approach to solar photo-Fenton operation. Raceway ponds as tertiary treatment technology

The photo-Fenton process has proven its efficiency in the removal of micropollutants. However, the high costs usually associated with it prevent a spread of this technology. An important factor affecting costs is the kind of photoreactor used, usually tubular with a reflecting surface. Tubular reactors like compound parabolic collectors, CPCs, involve high capital costs. In comparison, the application of less costly reactors such as the extensive raceway ponds (RPRs) would help to spread the use of the photo-Fenton process as tertiary treatment at commercial scale. As far as the authors know, RPRs have never been used in advanced oxidation processes (AOPs) applications. This work is aimed at studying the applicability of RPRs to remove micropollutants with solar photo-Fenton. For this purpose, a pesticide mixture of commercial acetamiprid (ACTM) and thiabendazole (TBZ) (100μg/L each) was used in simulated secondary effluent. Iron concentration (1, 5.5 and 10mg/L) and liquid depth (5, 10 and 15cm) were studied as process variables. TBZ was removed at the beginning of the treatment (less than 5min), although ACTM removal times were longer (20–40min for the highest iron concentrations). High treatment capacity per surface area was obtained (48mg/hm2 with 5.5mg Fe/L and 15cm liquid depth), proving the feasibility of using RPRs for micropollutant removal.

Induction of microtubule damage in Allium cepa meristematic cells by pharmaceutical formulations of thiabendazole and griseofulvin

Microtubules (MT) are formed by the assembly of α- and β-tubulins and MT-associated proteins. We characterized the effects of pharmaceutical formulations containing the microtubule disruptors thiabendazole (TBZ) and griseofulvin (GF) on the mitotic machinery of plant (A. cepa) meristematic cells. GF concentrations between 10 and 250μg/ml were tested. GF induced mitotic index inhibition and genotoxic effects, including chromosome fragments, bridges, lagged chromosomes, C-metaphases, tripolar cell division, disorganized anaphases and nuclear abnormalities in interphase cells. Efects on the mitotic machinery were studied by direct immunofluorescence with β-tubulin labeling and by DNA counterstaining with 4′,6-diamidino-2-phenylindole (DAPI). Exposure of meristematic root cells to TBZ or GF, 100μg/ml, caused microtubular damage which led to abnormal MT arrays. Our results suggest that GF induces abnormalities in spindle symmetry/polarity, while TBZ causes chromosome missegregation, polyploidy, and lack of cytokinesis.

An Electrochemical Method for High Sensitive Detection of Thiabendazole and Its Interaction with Human Serum Albumin

In this study, a simple and highly sensitive electroanalytical method for the determination of thiabendazole (TBZ) was developed using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) at carboxyl-functionalized multi-walled carbon nanotubes (MWCNT-COOH) modified glassy carbon electrode (MWCNT-COOH/GCE) in phosphate buffer solution (pH = 6.0). MWCNT-COOH/GCE exhibits an enhanced effectiveness for the redox of TBZ. This constructed biosensor exhibited two linear relationships with TBZ concentration range from 5.00 × 10−7 to 4.95 × 10−6 mol/L and 4.95 × 10−6 to 9.80 × 10−5 mol/L, respectively. The detection limit was 3.0 × 10−7 mol/L (S/N = 3) and the relative standard deviation (R.S.D.) was lower than 4.2 % (n = 6). The proposed method was successfully applied to determine TBZ in real samples and the results were satisfactory. The MWCNT-COOH/GCE electrode showed good reproducibility, stability, and anti-interference. The electrochemistry method was also described for the evaluation of TBZ and human serum albumin (HSA) interaction. In the presence of HSA, the peak currents of TBZ decreased linearly due to the formation of a kind of electro-inactive complex. The binding constant between TBZ and HSA was obtained by DPV.

Identification and monitoring of thiabendazole transformation products in water during Fenton degradation by LC-QTOF-MS.

This work enabled the identification of major transformation products (TPs) of thiabendazole (TBZ) during the Fenton process. TBZ is a benzimidazole fungicide widely used around the world to prevent and/or treat a wide range of fruit and vegetable pathogens. The degradation of the parent molecule and the identification of the main TPs were carried out in demineralized water. The TPs were monitored and identified by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS/MS). Up to 12 TPs were tentatively identified. Most of them were eliminated after 15min of treatment time and originated from numerous hydroxylations undergone by the aromatic ring during the initial stages of the process.

Interaction of anthelmintic drug (thiabendazole) with DNA: Spectroscopic and molecular modeling studies

The interaction between thiabendazole (TBZ) and calf-thymus DNA (ct-DNA) was studied by experimental and molecular modeling methods. The intrinsic fluorescence of TBZ was quenched in the presence of ct-DNA. In competition experiments, TBZ could displace Hoechst 33258 (a minor groove binder to DNA), whereas it was unable to replace ethidium bromide (an intercalator). Potassium iodide could quench the fluorescence of TBZ, which indicated the nonintercalative mode of binding of TBZ to ct-DNA. UV absorbance of TBZ shows hyperchromic effect on the addition of DNA to the solution with negligible shift in wavelength. Salt effect studies showed the non-electrostatic nature of binding of TBZ to DNA. The viscosity of ct-DNA solution was almost unchanged on addition of TBZ. Circular dichroism (CD) spectra of DNA showed small changes in the presence of TBZ which is in agreement with groove binding mode of interaction. Moreover, from molecular modeling methods, a docked structure with minimum energy was obtained in which TBZ was located in minor grooves of ct-DNA.

Thiabendazole residue loading in dip, drench and wax coating applications to control green mould and chilling injury on citrus fruit

Green mould (caused by Penicillium digitatum) is a major cause of postharvest losses in citrus. Residue loading of thiabendazole (TBZ) with application methods typically used in South African packhouses and green mould control was studied. TBZ was applied curatively and protectively in dip, drench and wax coating treatments and fruit were inoculated with a TBZ-sensitive or a TBZ-resistant isolate of P. digitatum. The dip treatments consisted of TBZ concentrations of 0–2000μgmL−1; fruit were dipped for 60s at 22°C at a pH of 7. Residues differed between fruit batches and ranged from 0.5 to 1.7μgg−1 at 1000μgmL−1 TBZ. Curative dip treatments almost completely controlled green mould (>96% at 1000μgmL−1 TBZ). The residue level needed for 75% curative control ranged from 0.06 to 0.22μgg−1, depending on citrus type. Protective treatments were unreliable and control varied from 17% to 97.9% at 1000μgmL−1 TBZ between fruit batches. Drench treatments consisted of exposure times of 30, 60 and 90s with 1000 or 2000μgmL−1 TBZ. Average TBZ residues were 2.14μgg−1 for Clementine mandarin fruit and 3.50μgg−1 for navel orange fruit. Green mould control on navel orange fruit resulted in 66–92%, 34–90% and 9–38% control for curative treatments after 6 and 24h and protective treatments, respectively, depending on fruit batch. Wax with 4000μgmL−1 TBZ was applied at 0.6, 1.2 and 1.8Lwaxton−1 fruit. Chilling injury was evaluated after fruit storage at −0.5°C for 40 days. Average TBZ residues loaded was 1.3, 1.3 and 2.7μgg−1 at the recommended 1.2Lton−1 for Satsuma mandarin, Clementine mandarin and Valencia orange fruit, respectively. Protective treatments showed lower infection levels (14–20%) than curative treatments (27–40%) for Valencia orange fruit. The same trend was observed with Satsuma (92–95% curative; 87–90% protective) and Clementine mandarin fruit (82–90% curative; 59–88% protective), but control was relatively poor. TBZ application in wax exceeded 5μgg−1 at higher wax loads (1.2 and 1.8Lton−1). Wax treatments showed a significant reduction in chilling injury; TBZ had an additive effect. TBZ resistant isolates could not be controlled.

Variability of the egg hatch assay to survey benzimidazole resistance in nematodes of small ruminants under field conditions

The egg hatch assay (EHA) is one of the main in vitro methods for detection of benzimidazole resistance in nematode parasites of small ruminants. However, although the EHA has been standardised at the laboratory level, the diagnostic performance of this method has not been fully characterised for field screenings. In the present work, monthly variation of benzimidazole resistance estimated by EHA was surveyed over two years in three sheep flocks and in one goat and an additional sheep flock sharing the same pastures. Resistance was measured by calculating both the effective dose of thiabendazole (TBZ) that inhibited hatching of ≥50% of parasite eggs (ED50) and the proportion (Pdd) of eggs hatching at a discriminating dose of 0.1μg/ml TBZ. Pdd exhibited higher variability than ED50, in agreement with the higher sensitivity of Pdd to changes in resistance levels. Both resistance parameters, however, were highly correlated, and their variation was similarly related to the same factors. Resistance levels differed among sheep flocks, and the resistance level of the goat flock was higher than that measured for the sheep flock sharing the same pasture. Moreover, monthly variation of resistance in goats did not mirror that recorded in sheep. Resistance levels varied seasonally, with the highest values recorded in the spring, and they were inversely related to the number of days that samples were stored under anaerobic conditions. In addition, they were directly associated with the relative abundance of Teladorsagia spp. but inversely related to the relative abundance of Haemonchus spp. After controlling for the effects of these identified factors for variation, inter-monthly sampling variation due to unknown factors was the main source of variability, accounting for more than 60–70% of variance for both resistance parameters and yielding absolute estimation errors higher than 0.06 for ED50 or 0.2 for Pdd when resistance was estimated from a single sampling. Optimum sample size, estimated from variance components, suggested that at least 4–5 samplings would be needed to halve this absolute error, whereas additional samplings would slightly increase precision but at the cost of substantially increasing sampling effort. More research is needed to identify the main factors involved in this inter-sampling variation to standardise the implementation of EHA under field conditions.

Phenomenological study and application of the combined influence of iron concentration and irradiance on the photo-Fenton process to remove micropollutants

The presence of low concentrations of persistent pollutants in waters (μg/L or ng/L), also called micropollutants, brings as a consequence the need to apply advanced oxidation treatments for their removal. The successful application of solar-driven photo-Fenton to treat highly polluted wastewaters (g/L and mg/L of pollutants) has prompted its application to lowly polluted effluents. However, a decrease in contaminant concentration may involve an alteration in the intrinsic process phenomenon, which until now has only been widely studied at the milligram-per-litre level or higher with this process. The aim of this research was to study the combined influence of the operating variable (iron concentration) and the environmental variable (irradiance) and application on the photo-Fenton process at pH2.8 when removing micropollutants. For this purpose, experimentation was carried out at laboratory and pilot plant scales with a biocide mixture of acetamiprid (ACTM), thiabendazole (TBZ) and imazalil (IMZ) (100μg/L each) as the model pollutant. Results indicated that above 15WUV/m2 and a light path length of 5cm (the most commonly used path for this type of application) iron concentration limited the process and there was irradiance excess under these conditions. On the other hand, and given the circumstances of irradiance excess, a higher light path length (10cm) was assessed. Results showed that path lengths wider than 5cm are recommended since more wastewater volume could be treated with a higher process rate per surface unit.

Phototransformation of benzimidazole and thiabendazole inside cucurbit[8]uril

The phototransformation of benzimidazole (BZ) and of the benzimidazole pesticide thiabendazole (TBZ) was investigated in aqueous solution in the absence and presence of the supramolecular host cucurbit[8]uril (CB8). ESI-MS and NMR reveal that both compounds form stable 1 : 2 host-guest complexes with CB8 (BZ2@CB8, TBZ2@CB8). The phototransformation of free BZ leads to dehydrodimerization, while for TBZ the photoreactivity leads to BZ, benzimidazole-2-carboximide and 2-acetylbenzimidazole. Inside CB8, BZ undergoes photohydrolysis to form 2-aminoformanilide, while for TBZ2@CB8 additional photoproducts were observed which are pH dependent. At pH 1.2 photolysis of TBZ2@CB8 leads to new red-shifted photoproducts with extended π conjugation.

Fray Pedro de Gante (1480?-1572): la palabra y la fe

Fray Pedro de Gante (Pieter van der Moere) was an important evangelist and teacher in the New Spain. With two of his fellow missionaries, Fray Juan de Tecto and Fray Juan de Ayora, he led the way in the difficult task of learning the language of those to be converted and becoming an exam­ple of holiness, humility and generosity. Fray Pieter van der Moere was loved and respected for his industriousness to learn Nahuatl and the culture of its speakers. In this article, his work is analyzed taking into account his work as a teacher, his example of life as a follower of St. Francis and his knowledge of the language, i.e. in the love of words and faith, which allowed him to write various Christian doctrines adapting the new evangelical message to the culture of the Nahuas. The content and the value representing the religious-philological context of the Evangelization is described in these doctrines.

Micellar electrokinetic chromatography method development for simultaneous determination of thiabendazole, carbendazim, and fuberidazole

Thiabendazole (TBz), carbendazim (CBz), and fuberidazole (FBz) are systemic benzimidazole-type fungicides used for pre- and post-harvest treatment to control various types of fungal diseases on a variety of crops. Significant levels of these fungicides could alter the composition or flavour of crops, and being possible carcinogens, they could also pose risks for humans and the environment. A mode of capillary electrophoresis called micellar electrokinetic chromatography (MEKC) was investigated for the determination of these three benzimidazole fungicides. The study involved two kinds of surfactants in which several experimental conditions were optimized, i.e., buffer concentration, pH, micelle concentration, and percent organic modifier (methanol). Using the optimum experimental conditions, the fungicides were successfully separated by MEKC. The limits of detection and quantification were in the range of 0.6–0.7 and 2.1–2.5 mg L−1, respectively, and the calibration curves were linear over the range of 5–60 mg L−1 for the three fungicides. The potential of the proposed MEKC method was demonstrated by analyzing water samples which were fortified with the fungicides. The proposed method enabled simultaneous determination of the three benzimidazole fungicides and method validation with spiked water samples yielded satisfactory quantitative recoveries for all the three fungicides.

Novel metal-ion-mediated, complex-imprinted solid-phase microextraction fiber for the selective recognition of thiabendazole in citrus and soil samples

A novel metal-ion-mediated complex-imprinted-polymer-coated solid-phase microextraction (SPME) fiber used to specifically recognize thiabendazole (TBZ) in citrus and soil samples was developed. The complex-imprinted polymer was introduced as a novel SPME coating using a "complex template" constructed with Cu(II) ions and TBZ. The recognition and enrichment properties of the coating in water were significantly improved based on the metal ion coordination interaction rather than relying on hydrogen bonding interactions that are commonly applied for the molecularly imprinting technique. Several parameters controlling the extraction performance of the complex-imprinted-polymer-coated fiber were investigated including extraction solvent, pH value, extraction time, metal ion species, etc. Furthermore, SPME coupled with HPLC was developed for detection of TBZ, and the methods resulted in good linearity in the range of 10.0-150.0 ng/mL with a detection limit of 2.4 ng/mL. The proposed method was applied to the analysis of TBZ in spiked soil, orange, and lemon with recoveries of 80.0-86.9% and RSDs of 2.0-8.1%. This research provides an example to prepare a desirable water-compatible and specifically selective SPME coating to extract target molecules from aqueous samples by introducing metal ions as the mediator.

Effect of the Al/clay ratio on the thiabendazol removal by aluminum pillared clays

In this work, four aluminum pillared clays (Al-PILC) with different Al/clay ratios were synthesized and evaluated for the removal of thiabendazole (TB) (a fungicide widely used in agricultural activities) from aqueous media. The Al-PILC were thoroughly characterized by different techniques, such as X-ray diffraction (XRD), thermogravimetric analysis (DTA-TG), adsorption–desorption of N2 at 77K, NH3-temperature programmed desorption (NH3-TPD) and transmission electron microscopy (TEM). The TB-adsorption studies were carried out in batch, at room temperature, at pH=6 (natural pH, without additional control) and with different concentrations of TB (2–100ppm). The measured TB adsorption capacities varied from 11.78 to 17.50mg TB per gram of clay. The TB–Al PILC complexes obtained after the adsorption process were studied by X-ray photoelectron spectroscopy (XPS). The results suggested that the molecules of TB were adsorbed on the Al-PILC by two different phenomena: by physisorption in their porous structure and by chemisorption on their pillars, showing a concordance between the amounts of incorporated aluminum in the pillared clays and their fungicide adsorption capacity.

Benzimidazole-resistant gastrointestinal nematodes in indigenous Chiapas and Pelibuey sheep breeds from Chiapas, Mexico

Because of the natural adaptation of Mexican sheep, the aim of the present study was to identify the presence or absence of gastrointestinal parasitic nematodes (GIN) resistant to benzimidazole (BZ) in both Chiapas and Pelibuey sheep breeds on local farms. Both male and female GIN-infected grazing sheep of the two breeds were selected. Sheep faecal samples were collected to obtain infective larvae (L3). This evolving stage of the parasite was used for taxonomic identification of the genus, based on its morphological characteristics. BZ anthelmintic resistance was evaluated using a nematode-compound in vitro interaction bioassay and the allele-specific polymerase chain reaction technique to detect mutations of residues 198 and 200 on isotype 1 of the β-tubulin gene. Three BZ-based compounds (febendazole (FBZ), tiabendazole (TBZ) and albendazole (ABZ)) at concentrations of 1, 0.5, 0.25, 0.125, 0.062 and 0.03mg/ml were used to estimate the anthelmintic efficacy and lethal dose (LD50, LD90 and LD99) of the drugs. Two parasitic nematodes, Haemonchus and Teladorsagia, were identified in both isolates. Also, the proportions of anthelmintic resistance identified in GIN of the two sheep breeds were 68% in isolates from the Chiapas breed and 71.8% in the Pelibuey breed. The specific lethal activity obtained with FBZ was higher than 90%. However, TBZ and ABZ showed a lethal activity lower than 50%. High variability in the discriminating dose values was found among the BZ drugs. For example, FBZ LD ranged from 0.01 to 1.20mg/ml; on the other hand, TBZ and ABZ required a dose ranging from 0.178 to 759mg/ml. In addition, amino acid changes of Phe (TTC) to Tyr (TAC) at codon 200 of the β-tubulin gene, showing resistance to BZ, and no changes at codon 198 Glu (GAA) to Ala (GCA) were observed for both isolates. These results confirmed the presence of a genetic mutation associated with BZ in both Chiapas and Pelibuey nematode isolates.

Detection of benzimidazole resistance in gastrointestinal nematodes of sheep and goats of sub-Himalyan region of northern India using different tests

The present investigation was planned with the objective of studying the status of benzimidazole (BZ) resistance in gastrointestinal nematodes (GIN) of sheep and goats of different agro-climatic zones of sub-Himalyan region of northern India using in vivo faecal egg count reduction test (FECRT) and in vitro tests namely egg hatch assay (EHA) and larval development assay (LDA).Out of fourteen flocks, FECRT detected resistance in eight flocks (two sheep flocks and six goat flocks) with FECR% ranging from 54.95 to 90.86. Pre treatment coproculture contained predominantly Haemonchus contortus, followed by Trichostrongylus spp., Oesophagostomum and Strongyloides, while post treatment coproculture results showed that only H. contortus survived fenbendazole (FBZ) (in FECRT) or thiabendazole (TBZ) (in LDA) treatment except in three flocks of Tarai region {one sheep flock (Us1), and two goat flocks (Ug1 and Ug5)} where BZ resistant Trichostrongylus were also detected. The GIN of those eight farms which were found resistant by FECRT were also detected resistant by EHA. Arithmetic mean and range of ED50 value of susceptible group was found to be 0.059μg/ml and 0.037–0.096μg/ml, respectively, and the same for the resistant group were found to be 0.119μg/ml and 0.101–0.147μg/ml, respectively. With LDA, the arithmetic mean and range of LC50 value of susceptible group was found 0.0030μg/ml and 0.001–0.005μg/ml, respectively, and those of resistant group was found 0.0105μg/ml and 0.009–0.012μg/ml, respectively. The values of Spearman rank correlation coefficient indicated that negative correlation was found between FECR% and ED50 and between FECR% and LC50 while positive correlation existed between ED50 and LC50 value and the p-values indicated that these correlations were statistically highly significant. In the present study, FECRT and EHA gave comparable results with regard to detection of BZ resistance in GIN in sheep and goats. Although with LDA, the threshold LC50 value could not be established as for EHA but LDA indicated the presence of low level of resistance in GIN of both sheep and goats. For effective worm control, regular monitoring for anthelmintic resistance is important to know the status of anthelmintic efficacy in a particular agro-climatic zone. The baseline information thus generated will enable timely management of benzimidazoles resistance in GIN.

Detection of thiabendazole applied on citrus fruits and bananas using surface enhanced Raman scattering

Thiabendazole (TBZ) is a chemical fungicide and parasiticide largely used in food industry against mold and blight in vegetables and fruits during transportation and long term deposit. We investigated the possibility to detect and monitor the TBZ from the chemically treated bananas and citrus fruits available on Romanian market, using surface enhanced Raman spectroscopy (SERS) with a compact, portable, mini-Raman spectrometer. To assess the potential of the technique for fast, cheap and sensitive detection, we report the first complete vibrational characterization of the TBZ in a large pH and concentration range in conjunction with the density functional theory (DFT) calculations. From the relative intensity of the specific SERS bands as a function of concentration, we estimated a total amount of TZB as 78mg/kg in citrus fruits, 13 times higher than the maximum allowed by current regulations, whereas in banana fruit the value was in the allowed limit.

Fate of thiabendazole through the treatment of a simulated agro-food industrial effluent by combined MBR/Fenton processes at μg/L scale

This study has been carried out to assess the performance of a combined system consisting of a membrane bioreactor (MBR) followed by an advanced oxidation process (Fenton/Photo-Fenton) for removing the fungicide thiabendazole (TBZ) in a simulated agro-food industrial wastewater. Previous studies have shown the presence of TBZ in the effluent of an agro-food industry treated by activated sludge in a sequencing batch reactor (SBR), thus reinforcing the need for alternative treatments for removal. In this study, a simulated agro-food industry effluent was enriched with 100 μg L−1 TBZ and treated by combined MBR/Fenton and MBR/solar photo-Fenton systems. Samples were directly injected into a highly sensitive liquid chromatography-triple quadrupole-linear ion trap-mass spectrometer (LC-QqLiT-MS/MS) analytical system to monitor the degradation of TBZ even at low concentration levels (ng L−1). Results showed that the biological treatment applied was not effective in TBZ degradation, which remained almost unaltered; although most dissolved organic matter was biodegraded effectively. Fenton and solar photo-Fenton, were assayed as tertiary treatments. The experiments were run without any pH adjustment by using an iron dosage strategy in the presence of excess hydrogen peroxide. Both treatments resulted in a total degradation of TBZ, obtaining more than 99% removal in both cases. To assure the total elimination of contaminants in the treated waters, transformation products (TPs) of TBZ generated during Fenton degradation experiments were identified and monitored by liquid chromatography–quadrupole time-of-flight mass spectrometry (LC-QTOF-MS/MS). Up to four TPs could be identified. Two of them corresponded to mono-hydroxylated derivatives, typically generated under hydroxyl radicals driven processes. The other two corresponded with the hydrolysis of the TBZ molecule to yield benzoimidazole and thiazole-4-carboxamidine. All of them were also degraded during the treatment.