Determination of the residue levels of nicarbazin and combination nicarbazin-narasin in broiler chickens after oral administration

The depletion times of the anticoccidial nicarbazin administered individually and of nicarbazin and narasin administered in combination were evaluated by determining the presence and levels of 4,4'-dinitrocarbanilide (DNC), the marker residue for nicarbazin, and narasin residues in the muscle tissues of broiler chickens subjected to a pharmacological treatment. A high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was used. The results showed the presence of all anticoccidial residues; however, the DNC levels were higher when the nicarbazin was administered individually than when it was used in association with narasin throughout the experimental period. After six days of withdrawal, the DNC level following nicarbazin administration alone was lower than the maximum residue level (MRL) of 200 μg kg^-1. However, when the nicarbazin was co-administered with narasin, the concentrations of DNC were lower than the MRL after four days of withdrawal. These results may be justified because the dosage of nicarbazin, when administrated individually, is greater than when it is used in combination with narasin. The levels of narasin were lower than the MRL of 15 μg kg^-1 throughout the evaluation period. It was concluded that nicarbazin is rapidly metabolized from the broiler muscles up to six days of withdrawal since the DNC levels were lower than the maximum residue level (MRL) and the concentrations of narasin were lower than the MRL throughout the evaluation period.

Development, validation and different approaches for the measurement uncertainty of a multi-class veterinary drugs residues LC-MS method for feeds

A sensitive method for the simultaneous residues analysis of 62 veterinary drugs in feeds by liquid chromatography-tandem mass spectrometry has been developed and validated in accordance to Commission Decision 657/2002/EC. Additionally, limits of detection (LOD), limits of quantitation (LOQ), matrix effects and measurement uncertainty were also assessed. Extraction was performed for all analytes and respective internal standards in a single step and chromatographic separation was achieved in only 12min. LOQ were set to 0.63-5.00μgkg^-1 (amphenicols), 0.63-30.00μgkg^-1 (avermectins), 0.63μgkg^-1 (benzimidazoles), 0.25-200.00μgkg^-1 (coccidiostats), 0.63-200.00μgkg^-1 (lincosamides and macrolides), 0.25-5.00μgkg^-1 (nitrofurans), 0.63-20.00μgkg^-1 (fluoroquinolones and quinolones), 15.00μgkg^-1 (quinoxaline), 0.63-7.50μgkg^-1 (sulfonamides), 0.63-20.00μgkg^-1 (tetracyclines), 0.25μgkg^-1 (β-agonists), and 30.00μgkg^-1 (β-lactams). The top-down approach was adequate for the calculation of measurement uncertainty for all analytes, except the banned substances, which should be rather assessed by the bottom-up approach. Routine analysis of different types of feeds was then carried out. An interesting profile of residues of veterinary drugs among samples was revealed, enlightening the need for stricter control in producing animals. Among the total of 27 feed samples, 20 analytes could be detected/quantified, ranging from trace levels to very high concentrations. A high throughput screening/confirmatory method for the residue analysis of several veterinary drugs in feeds was proposed as a helpful control tool.

A simple and high-throughput method for determination and confirmation of 14 coccidiostats in poultry muscle and eggs using liquid chromatography - quadrupole linear ion trap - tandem mass spectrometry (HPLC-QqLIT-MS/MS): Validation according to European Union 2002/657/EC

A simple and fast quantitative and confirmatory multi-residue method was developed and validated for the determination of 14 coccidiostats residues in poultry muscle and eggs using liquid chromatography-tandem mass spectrometry (LC/MS-MS). The compounds were analyzed in a single run including lasalocid A, maduramicin, monensin, narasin, salinomycin, semduramicin, robenidine, diclazuril, toltrazuril, trimethoprim, clopidol, amprolium, diaveridine and nicarbazin (as the marker residue dinitrocarbanilide). A low-cost extraction and clean up procedure was optimized without the need of solid-phase extraction. Samples were extracted with acetonitrile followed by low-temperature clean up. Chromatographic separation was achieved using a C18 column, using water and acetonitrile, both containing 5mmolL^-1 of formic acid and 1mmolL^-1 ammonium acetate, as mobile phase. Coccidiostats were ionized in negative and positive mode and monitored simultaneously. The method was fully validated according with Commission Decision 2002/657/EC and was applied for >100 samples from the Brazilian National Residue Control Plan (NRCP). Parameters as precision, reproducibility, trueness, CCα and CCβ were determined. Trueness values were within the range 73-115%. Precision (repeatability and intermediate precision) ranged from 0.4% to 21% and intralaboratory reproducibility ranged from 6.3% to 27%, depending on matrix.

Investigation of enrofloxacin residues in broiler tissues using ELISA and LC-MS/MS

This study investigated the efficiency of an enrofloxacin ELISA test kit to detect the presence of enrofloxacin residues in broiler tissues compared with LC-MS/MS. Broiler tissues from 72 samples consisting of 60 breast muscle, six pools of livers (500 g each) and six pools of kidneys (500 g each) were obtained from six different slaughterhouses. Breast muscle from 10 carcasses and pools of livers and kidneys from approximately 200 carcasses of the same flock were collected from each slaughterhouse. ELISA and HPLC were used to identify and quantify the contamination of the samples with enrofloxacin. A total of 72% of the analysed samples contained enrofloxacin residues detected by the ELISA and 22.2% were detected by LC-MS/MS. The mean values of enrofloxacin contamination found in chicken breast by ELISA and HPLC were 8.63 and 12.25 μg kg(-1), respectively. None of the samples exceeded the maximum limit of 100 μg kg(-1) by both methods set by the European Union as well as the Brazilian Agriculture Ministry. All positive samples for enrofloxacin residues detected by LC-MS/MS were also positive by ELISA. These data confirm the efficiency of the ELISA test, and suggest its use as a screening method for enrofloxacin residues in poultry tissues due to its quick results, low price and ease of applicability.

High-throughput method for macrolides and lincosamides antibiotics residues analysis in milk and muscle using a simple liquid-liquid extraction technique and liquid chromatography-electrospray-tandem mass spectrometry analysis (LC-MS/MS)

A fast and simple method for residue analysis of the antibiotics classes of macrolides (erythromycin, azithromycin, tylosin, tilmicosin and spiramycin) and lincosamides (lincomycin and clindamycin) was developed and validated for cattle, swine and chicken muscle and for bovine milk. Sample preparation consists in a liquid-liquid extraction (LLE) with acetonitrile, followed by liquid chromatography-electrospray-tandem mass spectrometry analysis (LC-ESI-MS/MS), without the need of any additional clean-up steps. Chromatographic separation was achieved using a C18 column and a mobile phase composed by acidified acetonitrile and water. The method was fully validated according the criteria of the Commission Decision 2002/657/EC. Validation parameters such as limit of detection, limit of quantification, linearity, accuracy, repeatability, specificity, reproducibility, decision limit (CCα) and detection capability (CCβ) were evaluated. All calculated values met the established criteria. Reproducibility values, expressed as coefficient of variation, were all lower than 19.1%. Recoveries range from 60% to 107%. Limits of detection were from 5 to 25 µg kg(-1).The present method is able to be applied in routine analysis, with adequate time of analysis, low cost and a simple sample preparation protocol.

Development and validation of a bioanalytical method by LC-MS/MS for the quantification of the LAFIS 10 - an antimalarial candidate - and its pharmacokinetics first evaluation

A rapid and highly sensitive method by LC-MS/MS was developed and validated for the quantification of an antimalarial candidate (LAFIS10) in rat plasma using dexamethasone as internal standard (IS). The chromatographic separation was performed with a Poroshell 120 EC-C18 column. The mobile phase consisted of water (A) and acetonitrile (B), both containing 10 m m of ammonium formate and 0.1% formic acid, delivered in the form of elution gradient. The LAFIS10 was monitored using an electrospray ionization interface operating in the positive mode in multiple reaction monitoring mode, monitoring the transitions 681.47 → 538.2 for LAFIS10 and 393.20 → 355.30 for the IS. The flow rate was 500 μL/min. The column temperature was kept at 40 °C and the injection volume was 2 μL. The lower limit of quantification was of 10 ng/mL and linearity between 10 and 1000 ng/mL was observed, with an R(2)  > 0.99. The accuracy of the method was >90%. The relative standard deviations intra- and interday were <8.80 and <6.37%, respectively. The method showed sensitivity, linearity, precision, accuracy and selectivity required to quantify LAFIS 10 in preclinical pharmacokinetic studies according to criteria established by the US Food and Drug Administration and European Medicines Agency.

Uso inadequado de organofosforados: uma prática de risco para bovinos no Sul do Rio Grande do Sul

Com o objetivo de determinar as causas para o súbito aumento no número de surtos de intoxicação por organofosforados foram analisados nove surtos da intoxicação diagnosticados em bovinos no Laboratório Regional de Diagnóstico da Faculdade de Veterinária da Universidade Federal de Pelotas (LRD/UFPel) entre novembro de 2013 e fevereiro de 2014. Em todos os surtos os animais foram tratados com concentrações entre duas e 151 vezes maiores que a concentração recomendada de diazinon para banho carrapaticida utilizado nas diferentes propriedades. Contribuíram, ainda, para o grande número de casos de intoxicação a via de adminstração pour on não recomendada para os produtos utilizados e o intenso calor registrado na época de ocorrência dos surtos.

Chemical constituents and pharmacological profile of Gunnera manicata L. extracts

Gunnera perpensa L. (Gunneraceae) is a native South African plant widely used in traditional medicine as an antibacterial and antifungal. In southern Brazil there is the native species called Gunnera manicata L. that also belongs to the Gunneraceae. Nevertheless, there is no information about chemical and pharmacological properties of South American Gunnera species. Therefore this study aimed at assessing the phytochemical and pharmacological profiles of aqueous and methanol Brazilian G. manicata extracts. The results showed that antimicrobial activity in an agar diffusion assay was effective against Staphylococcus aureus and Candida albicans . Phenolic compounds were investigated by liquid chromatography coupled with a tandem mass spectrometer (LC-MS/MS) and all extracts presented gallic acid and only the methanol extract obtained from the leaves exhibited hyperoside. Rutin, quercetin and chlorogenic acid were not found in the samples analysed. Total phenolic content was higher in methanol extract and total flavonoid content was low in all extracts. Antioxidant activity was evaluated by the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical test, and all samples presented good to moderate antioxidant activity. These results encourage complementary studies on the chemical composition of the plant extracts focusing on isolation and structure elucidation of their active compounds.

Scope extension validation protocol: inclusion of analytes and matrices in an LC-MS/MS sulfonamide residues method

Validation is a required process for analytical methods. However, scope extension, i.e. inclusion of more analytes, other matrices and/or minor changes in extraction procedures, can be achieved without a full validation protocol, which requires time and is laborious to the laboratory. This paper presents a simple and rugged protocol for validation in the case of extension of scope. Based on a previously reported method for analysis of sulfonamide residues using LC-MS/MS, inclusion of more analytes, metabolites, matrices and optimisation for the extraction procedure are presented in detail. Initially, the method was applied only to liver samples. In this work, milk, eggs and feed were also added to the scope. Several case-specific validation protocols are proposed for extension of scope.