Determination of marker residues of quinoxaline-1,4-di-N-oxides and its prototype identification by liquid chromatography tandem mass spectrometry

Quinoxaline-1,4-di-N-oxides (QdNOs), such as carbadox, olaquindox, mequindox, quinocetone, etc. are a class of antibacterial drugs. Prototype drugs residues can not be detected due to their rapid metabolism in animals. Quinoxaline-2-carboxylic acid (QCA) and 3-methyl-QCA (MQCA) are their common marker residues, so it has been always a challenge to trace the specific QdNOs drug used in food animal production. Herein, a liquid chromatography tandem mass spectrometry method was developed to determine QCA and MQCA, and meanwhile, the prototype drugs were identified by analyzing bis-desoxy QdNOs metabolites in single ion-pair monitoring mode. The method indicated that the average recoveries for QCA and MQCA were from 90 % to 105 % with relative standard deviations below 10 %, and the limits of quantification were 1.0 μg/kg. The limits of detection of five bis-desoxy QdNOs (qualitative markers) reached 0.5 μg/kg. This new analytical strategy can effectively solve the identification problem of QdNOs drugs in animal-derived food.

Pesticide residues in animal-derived food: Current state and perspectives

Pesticides are widely used in the cultivation and breeding of agricultural products all over the world. However, their direct use or indirect pollution in animal breeding may lead to residual accumulation, migration, and metabolism in animal-derived foods, posing potential health risks to humans through the food chain. Therefore, it is necessary to detect pesticide residues in animal-derived food using simple, reliable, and sensitive methods. This review summarizes sample extraction and clean-up methods, as well as the instrumental determination technologies such as chromatography and chromatography-mass spectrometry for residual analysis in animal-derived foods, including meat, eggs and milk. Additionally, we perspectives on the future of this field. This information aims to assist relevant researchers in this area, contribute to the development of ideas and novel technical methods for residual detection, metabolic research and risk assessment of pesticides in animal-derived food.

A new semiconductor heterojunction SERS substrate for ultra-sensitive detection of antibiotic residues in egg

Antibiotic residues in animal-derived food (egg) are threatening human health. Semiconductor heterojunction surface-enhanced Raman scattering (SERS) substrates can be used for ultra-sensitive detection of antibiotic residues in egg. Here, a TiO2/ZnO heterojunction was developed as a new SERS substrate based on an interface engineering strategy. Due to strong interfacial coupling and efficient carrier separating in heterostructure, utilization rate of photo-induced electrons in substrate was improved greatly, which realized the efficient charge transfer in substrate-molecule system, resulting in a prominent SERS enhancement. Taking the detection of enrofloxacin residue in egg as an example, the limit of detection (LOD) is only 13.1 μg/kg, which is far below the European Union standard, and lower than LODs of other conventional analytical methods and existing noble metal-based SERS methods. More importantly, benefiting from high sensitivity and selectivity of heterojunction and fingerprint characteristics of SERS, multiple antibiotic residues in egg can be identified simultaneously.

Highly ammonia-responsive starch/PVA film with gas absorption system as the 'bridge' for visually spoilage monitoring of animal-derived food

In the context of food waste and human diseases caused by food pollution, color renderement intelligent packaging came into being. Improving its indicator stability and sensitivity is essential for application. On the basis of our previous work, corn starch/polyvinyl alcohol was used as the matrix, the synthesized zirconium-based UiO-66 and anthocyanin-loaded ovalbumin-carboxymethylcellulose nanocomposites were embedded in to stabilize anthocyanins and improve gas adsorption performance of film. The study found that incorporating appropriate amount of UiO-66 (3%) in films resulted in uniform distribution and formation of holes. Mechanical properties, water stability and barrier properties were significantly improved, and gas adsorption capacity increased by approximately 10 times. More crucially, films that incorporate UiO-66 can react more quickly and visibly to lower concentrations of ammonia gas. The color change of SP/OVA-CMC-ACNs/3% UiO-66 film was noticeable (from purple to gray and then to green) when applied to monitor freshness of shrimp and pork.

Sensitive fluorescent detection of phosmet and chlortetracycline in animal-derived food samples based on a water-stable Cd(II) chain-based zwitterionic metal-organic framework

The residues of pesticides and antibiotics have always been a major concern in agriculture and food safety. In order to provide a new method for the rapid detection of organophosphorus pesticides and antibiotics, a novel Cd(II) chain-based zwitterionic metal-organic framework MOF 1 with high sensitivity fluorescence sensing performance was successfully synthesized. A series of researches showed that the water- and pH-stable bifunctional MOF 1 has a great ability to detect phosmet (PSM) and chlortetracycline (CTC) in water through fluorescence quenching effect, with high detection sensitivity, low detection limits (0.0124 μM and 0.0131 μM), short response time (40 s) and reusability. Practical application results revealed that MOF 1 could detect PSM and CTC in milk, beef, chicken and egg samples, with satisfactory recoveries (95.2%-103.7%). As a novel fluorescence probe, MOF 1, is known the first case that can detect PSM in animal-derived samples, and the first dual-function material capable of detecting PSM and CTC. Mechanism studies displayed that competitive absorption and photoinduced electron transfer clearly authenticate the high quenching performance of the material.

Application of multiple stable isotopes to aid identification of the origin of regional and organic animal products in Hesse, Germany

There is an increasing global demand for regional and organic produce. However, the growth of these markets depends on consumers' trust. Thus, novel methods must be developed to aid the verification of the origin of produce. We built on our previous study to identify the geographical origin and production method of animal-derived food products. Thirty-samples of eggs, 99 of milk, 34 of beef, and 62 of pork were collected from different regions in central Germany and analysed for their stable isotopic composition. The analysis followed a single-variate authentification approach using five isotope signatures, δ18O, δ2H, δ13C, δ15N, and δ34S. The best-performing indicators for verification of the geographical origin were δ15N and δ34S for beef; δ18O, δ2H, and δ13C for milk, and δ2H and δ13C for pork. These tracers indicated statistically significant differences among regions with the exception of pork; the results recorded for eggs were inconclusive. It was possible to distinguish between production methods by means of δ15N and δ34S (beef); all five tracers (eggs), and δ13C, δ15N, and δ34S (milk). This study demonstrated how the analysis of stable isotopes can be employed to determine the geographic region of origin and production method of animal-derived products in Germany.

Polyvinyl alcohol electrospun nanofiber membrane based solid-phase extraction for monitoring administered aminoglycoside antibiotics in various animal-derived foods

This work aims to develop a widely applicable method to monitor administered AGs in various animal-derived food samples to ensure food safety. A polyvinyl alcohol electrospun nanofiber membrane (PVA NFsM) was synthesized and employed as solid-phase extraction (SPE) sorbent, in combination with UPLC-MS/MS, for the simultaneous detection of ten AGs in nine types of animal-derived food samples. PVA NFsM exhibited excellent adsorption performance for the targets (with an adsorption rate of over 91.09%), good matrix purification ability (with a reduction of 7.65%-77.47% in matrix effect after SPE), and good recyclability (can be reused 8 times). The method displayed a linear range of 0.1-25000 μg/kg and attained limits of detection for AGs were 0.03-15 μg/kg. Spiked samples demonstrated a recovery of 91.72%-100.04% with a precision of<13.66%. The practicality of the developed method was verified by testing multiple actual samples.

Zanthoxylum bungeanum as a natural pickling spice alleviates health risks in animal-derived foods via up-regulating glutathione S-transferase, down-regulating cytochrome P450 1A

Endogenous aflatoxin B1 (AFB1) was quantified in five hundred and forty Hengshan goat meat samples (0.00 ± 23.09 μg kg^-1). Zanthoxylum bungeanum (Z. bungeanum), as a natural pickling spice, can ameliorate the flavor of animal-derived food (goat meat). Yet, considering the direct administration of Z. bungeanum in AFB1-contaminated goat meat, the degradation mechanisms of AFB1 remain elusive. Here, UHPLC-Q-Orbitrap HRMS-based integrative metabolomics (LOQ: 1.74-59.54 μg kg^-1) and proteomics analyses were executed to determine the effects of Z. bungeanum in the biotransformation of AFB1. Z. bungeanum (1.50 %, w/w) application mediated the metabolism of xenobiotics by cytochrome P450, significantly down-regulated cytochrome P450 1A and stimulated the up-regulation of glutathione S-transferase levels in AFB1-contaminated goat meat, leading to degradation of AFB1 (20.00-3.39 μg kg^-1). Metabolomics assays indicated that Z. bungeanum up-regulated l-histidine (1.43-2.21 mg kg^-1) and l-arginine, manifesting potential applications for the contribution of Z. bungeanum to the nutritional value of goat meat.

Human daily dietary intakes of antibiotic residues: Dominant sources and health risks

Antibiotic use in crops is an emerging concern, however, human exposure to antibiotics residues through consumption of plant-derived food has generally been neglected. This study is a comprehensive evaluation based on full consideration of exposure sources and analysis for nearly 100 antibiotics. A total of 58 antibiotic compounds were detected in drinking water (n = 66) and 49 in food samples (n = 150) from Shenzhen, China. The probable daily intake from drinking water and food consumption based on the total concentration of all the detected antibiotic compounds was 310, 200, and 130 ng/kg-body weight/day for preschool children, adolescents, and adults, with a maximum of up to 1400, 970 and 530 ng/kg-bw/day, respectively. Consumption of plant-derived food products, rather than animal-derived food, was the main source of the daily intake, and drinking water was a minor source. Risk assessment suggested a potentially unacceptable health risk from daily intake of norfloxacin, lincomycin and ciprofloxacin. Further research is warranted to alleviate food safety concerns related to antibiotic residues in plant-derived and animal-derived food products.

Flexible membrane composite based on sepiolite/chitosan/(silver nanoparticles) for enrichment and surface-enhanced Raman scattering determination of sulfamethoxazole in animal-derived food

A sepiolite/chitosan/silver nanoparticles (Sep/CTs/AgNPs) membrane substrate has been developed for the fast separation, enrichment, and surface-enhanced Raman scattering (SERS) determination of sulfamethoxazole all-in-one. The Sep/CTs/AgNPs membrane substrate possessed the ability of rapid separation and enrichment to simplify the process for pretreatment and improve the efficiency of analysis. The grown AgNPs can provide abundant hot spots and plasmonic areas to amplify the Raman signals of target molecules effectively. The membrane substrate exhibited good stability with relative standard deviations of 5.8% and 7.1% to same batch and different batches membrane substrate, respectively,  by detecting sulfamethoxazole. The SERS method based on Sep/CTs/AgNPs membrane substrate was used for the determination of sulfamethoxazole with a linear range of 0.05-2.0 mg/L, and the limit of detection was 0.020 mg/L. The established SERS method was finally applied to the quantification of sulfamethoxazole in animal-derived food samples. Sulfamethoxazole was actually found in crucian sample with 12.4 μg/kg, and the result was confirmed by a high-performance liquid chromatography method with relative error of 5.3%. The whole process of analysis can be finished within 25 min with recoveries of 89.3-102.2%. The SERS method based on Sep/CTs/AgNPs membrane substrate provided an integrated strategy for rapid and accurate SERS analysis in food safety issues.

Reliable performance of aggregation-induced emission nanoparticle-based lateral flow assay for norfloxacin detection in nine types of animal-derived food

The wide application of lateral flow assay (LFA) was limited by its low sensitivity and poor matric tolerance. Aggregation induced emission (AIE) materials show superior luminescence and good stability under close packing state, which may accelerate the development of LFA. However, the detection performance of the AIE-based LFA in different real samples was unclear. In this work, an AIE-LFA was established for norfloxacin (NOR) detection in nine types of animal-derived food. Results indicated that AIE-LFA had the average recovery range of 75.6%-95.1%, 78.6%-94.6%, 71.4%-112.7%, 81.7%-121.8%, 72.7%-93.5%, 79.8%-108.5%, 79.2%-109.4%, 76.3%-103.6%, and 80.6%-108.3% in pork, pig liver, fish, lamb, beef, milk, chicken, egg, and honey, respectively. The detection results of AIE-LFA were compatible with HPLC-MS/MS in detecting NOR in 135 real samples from nine types of animal-derived food. The developed AIE-LFA was sensitive and reliable for NOR detection in those real samples.

DNA barcoding and mini-barcoding in authenticating processed animal-derived food: A case study involving the Chinese market

This study used DNA barcoding and DNA mini-barcoding to test a variety of animal-derived food products sold in the Chinese market for potential mislabeling. Samples (52) including meat, poultry, and fish purchased from retail and online sources were examined. Regions of cytochrome C oxidase I (COI) gene (~650 bp) and 16S rRNA (~220 bp) were used as full- and mini-barcode markers, respectively. Approximately 94% (49 of 52) of the samples generated barcode sequences. The failure rate for full COI full-barcodes was 44%, but we obtained the 16S rRNA mini-barcode from 87% of the COI-failed cases. Overall, the survey revealed that 23% (12 of 52) of animal-derived products were mislabeled and, in most cases, contain undeclared species. Thus, regulatory measures and continuous monitoring for mislabeling of animal-derived products should be conducted.

Liver volatolomics to reveal poultry exposure to γ-hexabromocyclododecane (HBCD)

Hexabromocyclododecane (HBCD) is a critical emerging brominated flame retardant to which consumers can be exposed at high doses through a single food intake. Based on an animal experiment involving 3 groups of laying hens fed during 70 days with a control diet or γ-HBCD-contaminated diets at 0.1 or 10 μg γ-HBCD g^-1 feed, this study aims to use the volatolome of biological samples for revealing markers of livestock exposure to HBCD. Liquid chromatography-tandem mass spectrometry was used to monitor the time-course of HBCD levels in bodily samples. Each liver was analyzed by solid-phase microextraction-gas chromatography-mass spectrometry for volatolome profiling. After 70 days, γ-HBCD concentrations in egg yolk, fat, liver and serum reached 54 ± 4, 85 ± 6, 31 ± 6, and 32 ± 4 ng g^-1 lw, respectively, for the low exposure level and 4.6+/5.7, 7.8+/6.5, 3.9+/3.0 and 3.9+/6.1 μg g^-1 lw, respectively, for the high exposure level. Isomerization of γ-HBCD into α- and β-HBCD was observed in all tissues, at least for the high exposure level. Volatolome data allowed a significant discrimination between control and exposed animals whatever the feed contamination load, demonstrating a liver metabolic response to γ-HBCD exposure. The relevance of the twenty nine volatile exposure markers tentatively identified was discussed in light of literature data.

Hens can ingest extruded polystyrene in rearing buildings and lay eggs contaminated with hexabromocyclododecane

The overall concentration of hexabromocyclododecane (HBCDD) in eggs is low although abnormally high concentrations exceeding 3000 ng g^-1 lw have been reported. In order to test whether these contaminations may originate from the ingestion of insulating materials in rearing buildings, a group of 55 hens raised in a collective cage was provided with a 64-g piece of extruded polystyrene (XPS, 2.59% HBCDD of which 75, 15 and 10% as α-, β- and γ-HBCDD, respectively). Hens entirely consumed the piece within 3 days, leading to a mean daily exposure of 4.7 mg HBCDD per kg body weight. Whole egg HBCDD concentration reached a maximum of 1037 ng HBCDD g^-1 fresh weight (fw), recorded 2 days after the piece had disappeared, and decreased down to 86 ng g^-1 fw within the 19 following days. In all these samples, HBCDD was made of 98.7 ± 0.7 and 1.3 ± 0.6% α- and β-HBCDD, respectively, and 0.1% γ-HBCDD when quantified; it was enriched in (-)α- and (+)β-HBCDD with enantiomeric fractions of 0.438 ± 0.009 and 0.579 ± 0.030, respectively. HBCDD was quantified in all the individual eggs collected the last day of experiment at concentrations ranging between 0.47 and 1361 ng g^-1 fw, according to a lognormal distribution. The ingestion of XPS in degraded rearing buildings is thus a plausible cause of on-farm egg contamination by HBCDD which should be strictly avoided.

Accumulation of α-hexabromocyclododecane (α-HBCDD) in tissues of fast- and slow-growing broilers (Gallus domesticus)

The aim of the current study was to describe the fate of ingested α-hexabromocyclododecane (α-HBCDD) in fast-growing (FG) and slow-growing (SG) broilers, through an exposure to a dietary concentration of 50 ng α-HBCDD g^-1 feed during 42 and 84 days, respectively. Depuration parameters were assessed in SG broilers successively exposed during 42 days and depurated during 42 days. At market age, SG broilers had ingested 42% more feed than FG broilers, while their body weight gain per g of feed ingested was 34% lower. No isomerization of α- to β- or γ-HBCDD forms occurred, while OH-HBCDD was identified as a product of α-HBCDD metabolism. Irrespective of the strain, abdominal fat displayed the highest α-HBCDD concentration on a lipid weight basis, followed leg muscles and then breast muscle, liver and plasma. The accumulation ratios of α-HBCDD were slightly higher in SG (6.7, 2.1, 2.6 and 9.9 in leg muscles, breast muscle, liver and abdominal fat, respectively) than in FG broilers (5.2, 2.2, 1.1 and 8.4, respectively). The elimination half-lives in SG broilers were 20, 12 and 19 d in leg muscles, breast muscle and abdominal fat, respectively, to which dilution through growth contributed for around 50%. The overall assimilation efficiency of α-HBCDD was estimated at 58 and 50% in FG and SG broilers, respectively, while 22 and 17% of α-HBCDD ingested were estimated to be eliminated in excreta as metabolites.

Concentrations and health risk assessment of trace elements in animal-derived food in southern China

This study aimed to investigate the levels of trace elements in animal-derived food in Shenzhen, Southern China. The concentrations of 14 trace elements (Cd, Hg, Pb, As, Cr, Cu, Fe, Zn, Mn, Mo, Ni, Co, Se and Ti) in a total of 220 meat samples, collected from the local markets of Shenzhen were determined. Cu, Fe and Zn were the major elements, with concentrations approximately 2-3 orders of magnitude higher than those of other elements. However, the daily intakes of Cu, Fe and Zn merely via the consumption of the meat products were lower than the recommended nutrient intake values provided by the 2013 Chinese Dietary Guide. Among the non-essential trace elements, Cd was accumulated in animal viscera, and the concentration ratios of chicken gizzard/chicken, chicken liver/chicken, pig kidney/pork and pig liver/pork were 41.6, 55.2, 863 and 177, respectively. In addition, high concentrations of As were found in aquatic products, especially in marine fish. The concentration of As in marine fish was slightly higher than the limits recommended by China, USA and Croatia. The health risk assessment of trace elements through the consumption of meat products by adult residents in Shenzhen was evaluated by using the target hazard quotient (THQ) method. The total THQ was greater than 1, implying a potential health risk. Approximately 66% of total THQ values, mainly from As, were from the consumption of aquatic products.