Multiclass, multiresidue method for the detection of antibiotic residues in distillers grains by liquid chromatography and ion trap tandem mass spectrometry

Label-free electrochemical immunosensor based on staphylococcal protein a and AgNPs-rGO-Nf for sensitive detection of virginiamycin M1

Virginiamycin (VIR), a feed additive, is used to promote pig and poultry growth. However, it is hazardous to human health. This work described a label-free electrochemical immunosensor based on silver nanoparticles-reduced graphene oxide (AgNPs-rGO) nanocomposites and staphylococcal protein A (SPA) for the first time to directly detect the residual marker VIR M1. Good catalytic currents for oxygen reduction reaction were apparently obtained after the modification of nanocomposites on gold electrode. Nanocomposites were characterized using UV-Vis, X-ray diffraction (XRD) patterns, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). SPA was targeted to immobilize VIR M1 monoclonal antibody (mAb) by binding to Fc region of antibody. The proposed immunosensor showed a wide linear range from 0.25 ng mL^-1 to 100 ng mL^-1, providing detection limit (LOD) of 0.18 ng mL^-1 of VIR M1. Recovery rates ranged from 92.27% to 98.84%, and relative standard deviation (RSD) was not above 6.6%, indicating the immunosensor could detect VIR M1 in actual samples with high accuracy. The sensor showed good selectivity, reproducibility and stability and could be considered as a potential tool for detection of VIR M1 in feed and animal derived food.

An LC-MS/MS Method for the Determination of Antibiotic Residues in Distillers Grains: Collaborative Study

BACKGROUND

Antibiotics are used in ethanol production to discourage the growth of bacteria that would lower the yield of the product. Any antibiotic residues remaining in distillers grain co-product could lead to antimicrobial resistance, which is a public health concern. US. Food and Drug Administration (FDA)/Center for Veterinary Medicine (CVM) previously developed a LC-MS/MS analytical method to detect residues of erythromycin A, penicillin G, virginiamycin M1 & virginiamycin S1 in distillers grain to enable regulatory decision-making.

OBJECTIVE

The objective of this study was to ensure method's robustness by carrying out a multi-laboratory validation of the method.

METHODS

Test portions were extracted with a mixture of acetonitrile and buffer. The extract was cleaned by solid phase extraction. The concentrated eluant was reconstituted and analyzed by LC-MS/MS. Eight laboratories participated in the study.

RESULTS

Average accuracies for combined three matrices for all four compounds at all fortification levels ranged from 83 to 109% with repeatability RSDr (within laboratory) ≤17% and reproducibility RSDR (between laboratory) ≤21%. The HorRat values ranged 0.4-1.0 indicating that method reproducibility is acceptable.

CONCLUSIONS

A collaborative study was successfully conducted to evaluate an LC-MS/MS method for the determination of the drugs of interest in distillers grains. The results demonstrate that the method is fit-for-purpose to determine the drugs in distillers grain (DG) and could serve as a regulatory method capable of being used for compliance actions for DG containing these antibiotic contaminants.

HIGHLIGHTS

The method was posted to the FDA/Foods Program Compendium of Analytical Laboratory Methods. Distillers grain, a major co-product of dry-grind ethanol distillation, is an excellent animal feed supplement. However, any antimicrobial processing aids (i.e., antibiotics) remaining from the fermentation process could be a cause for regulatory concern if distillers grain is fed to animals. Only limited data were available to the U.S. Food and Drug Administration (FDA) on the extent and levels of antibiotics in distillers grain that were produced by either domestic or foreign ethanol facilities and marketed as animal feed ingredients in the U.S. Because of this limited data and because of the marked increase in the amount of distillers grain used in animal feed, regulators at the FDA intended to conduct a survey to determine the extent and levels of antibiotic residues in distillers grain. To enable this survey, an analytical method (1) was developed for thirteen antibiotics that belonged to several chemical classes. The surveys conducted by the FDA (2 & 3) using this method revealed several antibiotic residues in the distillers grain by-product used as an animal feed ingredient. This finding caused FDA to look more closely into the situation and prompted further investigations as low levels of antibiotic residues in DG may lead to antimicrobial resistance (AMR) development and become a public health concern. To quantitate antimicrobials in distillers grain at the low levels that could potentially lead to AMR development, FDA needed an analytical method that was significantly more sensitive than the previous screening method. Accordingly, a method was developed and single-laboratory validated that quantifies residues of erythromycin, penicillin G, virginiamycin M1 & virginiamycin S1 (Figure 1) in DG in the range 5 to 1200 ng/g (4) with a LOQ of 5 ng/g for all drugs. This range encompasses the 50-1000 ng/g concentration range FDA/Center for Veterinary Medicine (CVM) was targeting for. The distillers grain matrix used was dry distillers grains with solubles (referred to as DG, henceforth), the most prevalent type of distillers coproduct in the marketplace. Subsequently, the method was approved for a multi-laboratory collaborative validation (MLV) to adequately verify it to be robust and reliable for FDA's compliance and regulatory actions. The objective of this study was to carry out a collaborative MLV of the LC-MS/MS analytical method developed in FDA/CVM laboratory (4) to determine residues of erythromycin, penicillin G, virginiamycin M1 and virginiamycin S1 in DG.

Control of Antimicrobials in Feed Using Liquid Chromatography-Tandem Mass Spectrometry: Assessment of Cross-Contamination Rates at the Farm Level

Antimicrobial cross-contamination of animal feed may occur during feed manufacturing, because shared production lines can be used for the production of medicated and nonmedicated feeds, and also during feed transport, storage at the farm level, and usage. This is a major issue in the current context in which antimicrobial usage must be controlled to maintain their effectiveness. The purpose of this study was to assess the antimicrobial cross-contamination rate of feed at the farm level. Here, we optimized a liquid chromatography-tandem mass spectrometry method for the determination of 11 antimicrobials in feed for pigs, poultry, and rabbits, which were strategically chosen. The method was validated according to European regulations in terms of mass spectrometry identification criteria and quantification criteria (linearity, trueness, precision, limit of quantification, and limit of decision). The results were in compliance with these regulations except for doxycycline, which may be quantified with higher uncertainty. This method was applied to the analysis of 192 nonmedicated pig, poultry, and rabbit feed samples that were collected directly from farms to assess antimicrobials animal exposure. Cross-contamination rates were relatively high with 44% of the samples being contaminated at a concentration above the quantification limit of 0.125 mg/kg and 15% of the samples being contaminated above 1 mg/kg. This result suggests that the current regulations and feed processing recommendations need to be improved, taking into account the risks arising from these contaminations.

A review of analytical procedures for the simultaneous determination of medically important veterinary antibiotics in environmental water: Sample preparation, liquid chromatography, and mass spectrometry

Medically important (MI) antibiotics are defined by the United States Food and Drug Administration as drugs containing certain active antimicrobial ingredients that are used for the treatment of human diseases or enteric pathogens causing food-borne diseases. The presence of MI antibiotic residues in environmental water is a major concern for both aquatic ecosystems and public health, particularly because of their potential to contribute to the development of antimicrobial-resistant microorganisms. In this article, we present a review of global trends in the sales of veterinary MI antibiotics and the analytical methodologies used for the simultaneous determination of antibiotic residues in environmental water. According to recently published government reports, sales volumes have increased steadily, despite many countries having adopted strategies for reducing the consumption of antibiotics. Global attention needs to be directed urgently at establishing new management strategies for reducing the use of MI antimicrobial products in the livestock industry. The development of standardized analytical methods for the detection of multiple residues is required to monitor and understand the fate of antibiotics in the environment. Simultaneous analyses of antibiotics have mostly been conducted using high-performance liquid chromatography-tandem mass spectrometry with a solid-phase extraction (SPE) pretreatment step. Currently, on-line SPE protocols are used for the rapid and sensitive detection of antibiotics in water samples. On-line detection protocols must be established for the monitoring and screening of unknown metabolites and transformation products of antibiotics in environmental water.

Yeast Derived LysA2 Can Control Bacterial Contamination in Ethanol Fermentation

Contamination of fuel-ethanol fermentations continues to be a significant problem for the corn and sugarcane-based ethanol industries. In particular, members of the Lactobacillaceae family are the primary bacteria of concern. Currently, antibiotics and acid washing are two major means of controlling contaminants. However, antibiotic use could lead to increased antibiotic resistance, and the acid wash step stresses the fermenting yeast and has limited effectiveness. Bacteriophage endolysins such as LysA2 are lytic enzymes with the potential to contribute as antimicrobials to the fuel ethanol industries. Our goal was to evaluate the potential of yeast-derived LysA2 as a means of controlling Lactobacillaceae contamination. LysA2 intracellularly produced by Pichia pastoris showed activity comparable to Escherichia coli produced LysA2. Lactic Acid Bacteria (LAB) with the A4α peptidoglycan chemotype (L-Lys-D-Asp crosslinkage) were the most sensitive to LysA2, though a few from that chemotype were insensitive. Pichia-expressed LysA2, both secreted and intracellularly produced, successfully improved ethanol productivity and yields in glucose (YPD60) and sucrose-based (sugarcane juice) ethanol fermentations in the presence of a LysA2 susceptible LAB contaminant. LysA2 secreting Sacharomyces cerevisiae did not notably improve production in sugarcane juice, but it did control bacterial contamination during fermentation in YPD60. Secretion of LysA2 by the fermenting yeast, or adding it in purified form, are promising alternative tools to control LAB contamination during ethanol fermentation. Endolysins with much broader lytic spectrums than LysA2 could supplement or replace the currently used antibiotics or the acidic wash.

Analysis of Major Components of Bacitracin, Colistin and Virginiamycin in Feed Using Matrix Solid-phase Dispersion Extraction by Liquid Chromatography-electrospray Ionization Tandem Mass Spectrometry

A quantitative LC-MS/MS method has been developed for simultaneous determination of bacitracin A, bacitracin B, colistin A, colistin B and virginiamycin M1 in feed. This rapid simple and effective extraction method was based on matrix solid-phase dispersion. Qualitative and quantitative analyses were performed by LC-ESI-MS/MS. CCβ of polypeptide antibiotics upon the method ranged from 9.6 to 15.8 μg kg-1 and 19.4 to 27.5 μg kg-1, respectively. The limit of quantification of polypeptide antibiotics was 25 μg kg-1 in feed samples. The recoveries of polypeptide antibiotics spiked in feed samples at a concentration range of 25-100 μg kg-1 were found above 75.9-87.9% with relative standard deviations within days less than 15.7% and between days less than 20.6%. This rapid and reliable method can be used to efficiently separate, characterize and quantify the residues of polypeptide antibiotics in feed with advantages of simple pretreatment and environmental friendly.

The Role of Biofuels Coproducts in Feeding the World Sustainably

One of the grand challenges facing our society today is finding solutions for feeding the world sustainably. The food-versus-fuel debate is a controversy embedded in this challenge, involving the trade-offs of using grains and oilseeds for biofuels production versus animal feed and human food. However, only 6% of total global grain produced is used to produce ethanol. Furthermore, biofuels coproducts contribute to sustainability of food production because only 1% to 2.5% of the overall energy efficiency is lost from converting crops into biofuels and animal feed, and approximately one-third of the corn used to produce ethanol is recovered as feed coproducts. Extensive research has been conducted over the past 15 years on biofuels coproducts to (a) optimize their use for improving caloric and nutritional efficiency in animal feeds, (b) identify benefits and limitations of use in various animal diets,

Evaluation of Selected Nutrients and Contaminants in Distillers Grains from Ethanol Production in Texas

This article contains the results of the evaluation of distillers grain (DG) coproducts from different ethanol plants around the United States and supplemented in animal diets in Texas, based on samples analyzed from 2008 to 2014. The samples were assessed for concentration, occurrence, and prevalence of selected nutrients and contaminants. Protein and sulfur contents of DG were largely different between maize and sorghum coproducts, as well as wet distillers grain with solubles (WDGS) and dried distillers grain with solubles (DDGS), indicating a significant effect of grain feedstock and dry grind process stream on DG composition and quality. Salmonella was isolated in 4 DDGS samples of a total of 157 DG samples, a percentage (2.5%) that is lower than the percentage of Salmonella -positive samples found in other feed samples analyzed during the same period. A small amount of virginiamycin residue was found in 24 maize DDGS, 1 maize WDGS, and 2 sorghum DDGS samples of 242 samples in total. One sorghum DDGS sample of 168 DG samples was contaminated with animal protein prohibited for use in ruminant feed and was channeled to poultry feed. The concentrations of aflatoxin and fumonisin DG coproducts averaged 3.4 μg/kg and 0.7 mg/kg, respectively. Among contaminated maize DG samples, five DDGS samples for aflatoxin contained a higher concentration than the U.S. Food and Drug Administration (FDA) minimum action level of 20 μg/kg for use in animal feed, whereas no sample for fumonisin was found above the action level of 5 mg/kg. The study provides the most current results involving DG coproducts and associated hazards that will assist development of food safety plans required by the FDA in their September 2015 rule titled "Current Good Manufacturing Practice Hazard Analysis and Risk Based Preventive Controls for Food for Animals."

Development and validation of rapid multiresidue and multi-class analysis for antibiotics and anthelmintics in feed by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry

A new multi-residue method for the analysis of veterinary drugs, namely amoxicillin, chlortetracycline, colistins A and B, doxycycline, fenbendazole, flubendazole, ivermectin, lincomycin, oxytetracycline, sulfadiazine, tiamulin, tilmicosin and trimethoprim, was developed and validated for feed. After acidic extraction, the samples were centrifuged, purified by SPE and analysed by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry. Quantitative validation was done in accordance with the guidelines laid down in European Commission Decision 2002/657/CE. Matrix-matched calibration with internal standards was used to reduce matrix effects. The target level was set at the authorised carryover level (1%) and validation levels were set at 0.5%, 1% and 1.5%. Method performances were evaluated by the following parameters: linearity (0.986 < R(2) < 0.999), precision (repeatability < 12.4% and reproducibility < 14.0%), accuracy (89% < recovery < 107%), sensitivity, decision limit (CCα), detection capability (CCβ), selectivity and expanded measurement uncertainty (k = 2).This method has been used successfully for three years for routine monitoring of antibiotic residues in feeds during which period 20% of samples were found to exceed the 1% authorised carryover limit and were deemed non-compliant.

Structural elucidation of sulfaquinoxaline metabolism products and their occurrence in biological samples using high-resolution Orbitrap mass spectrometry

Four previously unreported metabolism products of sulfaquinoxaline (SQX), a widely used veterinary medicine, were isolated and analyzed using liquid chromatography coupled to high-resolution Orbitrap mass spectrometry. Metabolites were structurally elucidated, and a fragmentation pathway was proposed. The combination of high-resolution MS(2) spectra, linear ion trap MS(2), in-source collision-induced dissociation (CID) fragmentation, and photolysis were used to analyze SQX and its metabolites. All metabolism products identified showed a similar fragmentation pattern to that of the original drug. Differential product ions were produced at m/z 162 and 253 which contain the radical moiety with more 16 Da units than sulfaquinoxaline. This occurs by a hydroxyl attachment to the quinoxaline moiety. With the exception of two low-intensity compounds, all the mass errors were below 5.0 ppm. The distribution of these metabolites in some animal species are also presented and discussed.

Presence and biological activity of antibiotics used in fuel ethanol and corn co-product production

Antibiotics are used in ethanol production to control bacteria from competing with yeast for nutrients during starch fermentation. However, there is no published scientific information on whether antibiotic residues are present in distillers grains (DG), co-products from ethanol production, or whether they retain their biological activity. Therefore, the objectives of this study were to quantify concentrations of various antibiotic residues in DG and determine whether residues were biologically active. Twenty distillers wet grains and 20 distillers dried grains samples were collected quarterly from 9 states and 43 ethanol plants in the United States. Samples were analyzed for DM, CP, NDF, crude fat, S, P, and pH to describe the nutritional characteristics of the samples evaluated. Samples were also analyzed for the presence of erythromycin, penicillin G, tetracycline, tylosin, and virginiamycin M1, using liquid chromatography and mass spectrometry. Additionally, virginiamycin residues were determined, using a U.S. Food and Drug Administration-approved bioassay method. Samples were extracted and further analyzed for biological activity by exposing the sample extracts to 10(4) to 10(7) CFU/mL concentrations of sentinel bacterial strains Escherichia coli ATCC 8739 and Listeria monocytogenes ATCC 19115. Extracts that inhibited bacterial growth were considered to have biological activity. Physiochemical characteristics varied among samples but were consistent with previous findings. Thirteen percent of all samples contained low (≤1.12 mg/kg) antibiotic concentrations. Only 1 sample extract inhibited growth of Escherichia coli at 10(4) CFU/mL, but this sample contained no detectable concentrations of antibiotic residues. No extracts inhibited Listeria monocytogenes growth. These data indicate that the likelihood of detectable concentrations of antibiotic residues in DG is low; and if detected, they are found in very low concentrations. The inhibition in only 1 DG sample by sentinel bacteria suggests that antibiotic residues in DG were inactivated during the production process or are present in sublethal concentrations.

Hydrophilic interaction chromatography in drug analysis

Hydrophilic interaction chromatography (HILIC) is an increasingly popular alternative to conventional HPLC for drug analysis. It offers increased selectivity and sensitivity, and improved efficiency when quantifying drugs and related compounds in complex matrices such as biological and environmental samples, pharmaceutical formulations, food, and animal feed. In this review we summarize HILIC methods recently developed for drug analysis (2006–2011). In addition, a list of important applications is provided, including experimental conditions and a brief summary of results. The references provide a comprehensive overview of current HILIC applications in drug analysis.

Development and validation of a multiclass method for the determination of veterinary drug residues in chicken by ultra high performance liquid chromatography-tandem mass spectrometry

A multiclass method has been optimized and validated for the simultaneous determination of 20 veterinary drug residues belonging to several classes, as quinolones, sulfonamides, macrolides, anthelmintics, avermectins and diamino derivatives, and benzathine, used as a marker of the presence of penicillin, in muscle chicken. It has been based on QuEChERS methodology (quick, easy, cheap, effective, rugged and safe) and ultra high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-MS/MS). Several chromatographic conditions were optimized, obtaining a running time <8.5 min. The developed method was validated on the basis of international guidelines. Mean recoveries ranged from 70 to 120%, except for benzathine (65.6% at 20 μg kg(-1)) and sulfadimidine (69.0% at 100 μg kg(-1)). Repeatability was lower than 20.0% except for sulfachlorpyridazine (22.1% at 20 μg kg(-1)) and tylosin (20.5% and 20.6% at 30 and 50 μg kg(-1), respectively), whereas reproducibility was lower than 25% except for flumequine (27.4% at 20 μg kg(-1)) and benzathine (37.8% and 27% at 20 and 50 μg kg(-1), respectively). Limits of detection (LODs) and quantification (LOQs) ranged from 3.0 to 6.0 μg kg(-1) and 10.0 to 20.0 μg kg(-1), respectively, except for tylosin that showed a LOD and LOQ of 9.0 and 30.0 μg kg(-1). Decision limit (CC(α)) and detection capability (CC(β)) were calculated and CC(β) ranged from 24.1 μg kg(-1) (mebendazole) to 423.6 μg kg(-1) (flumequine). Finally, the method was applied to real samples and traces of some compounds were found in eight samples of chicken and benzathine was detected in one sample at 29.9 μg kg(-1).