Validation of I'screen AFLA M1 Milk for Detection of Aflatoxin M1 in Raw Bovine Milk and Powdered Milk: AOAC Performance Tested MethodSM 072002.

BACKGROUND: Aflatoxin M1 (AFM1) is the major metabolite of Aflatoxin B1 (AFB1) and can be found in the milk of animals fed with feed containing AFB1. The frequency of occurrence of AFM1 in milk has led to the development of specific quantitative methods of analysis to mitigate the risk of adversely affecting human health. OBJECTIVE: To demonstrate that the I'screen AFLA M1 Milk ELISA kit can quantify AFM1 in raw bovine milk and powdered milk. METHOD: Assay performance was evaluated studying lot-to-lot consistency, assay stability, robustness, and possible interferences of related molecules. Raw bovine milk samples spiked at 0, 5.0, 20, 50, 100, and 200 ng/L of AFM1 and powdered milk reference materials and spiked samples at 100 and 200 ng/L were tested to determine recovery, repeatability, and bias. LOD and LOQ were also determined for both matrices. RESULTS: High selectivity for AFM1 was demonstrated and performances were consistent, robust, and stable. The LOQ was validated at 5 ng/L for raw milk and 50 ng/L for powdered milk. Recoveries for spiked raw and powdered milk were 97-122%, with RSDr < 10%, and 106-111% for reference materials, with RSDr < 5%. CONCLUSIONS: The data collected validate the method as a selective, specific, sensitive, accurate, and precise tool for the analysis of AFM1 in raw bovine milk and powdered milk. HIGHLIGHTS: We demonstrated that I'screen AFLA M1 is a reliable kit and a proper screening tool suitable for high analytical throughputs.

Development of a nanoarray capable of the rapid and simultaneous detection of zearalenone, T2-toxin and fumonisin.

Fusarium mycotoxins such as trichothecenes, zearalenone and fumonisins occur on a worldwide basis in cereal grains, animal feeds and forages. Practical solutions for multiple mycotoxin determination in samples are required by industry and regulators for cost effective screening purposes. The feasibility of developing a novel multiplex nanoarray for the simultaneous and semi-quantitative detection of three regulated mycotoxins: zearalenone (ZEA), T2-toxin (T2) and fumonisin B1 (FUM) was examined. Additionally, the assay was also able to detect HT2 toxin and fumonisin B2 and B3 due to the cross reactivity profiles of the antibodies used. Individual mycotoxin conjugates specific to the three mycotoxins were nano-spotted onto wells of a microtitre plate. Optimisation of assay parameters and antibodies was undertaken with both individual and multiplex calibration curves generated. A competitive assay format was employed enabling a calibration curve for concentration analysis and duplicate results for up to 40 samples in 70min for the three target mycotoxins. The characteristics and performance of the nanoarray were evaluated including sensitivity and specificity for each target. Additionally, intra and inter spotting precision, cross reactivity, matrix effects and sample analysis in maize and wheat (n=8) was performed. Sensitivity, determined as the concentration causing 50% inhibition, was 70.1, 2.8 and 90.9ppb in PBS, 172.4, 3.2 and 129.3ppb in methanol, 197.4, 0.7 and 216.7ppb in wheat and 43.6, 0.5 and 25.9ppb in maize for ZEA, T2 and FUM respectively. Intra spotting precision was 6%, 11% and 10% for PBS and 5%, 11% and 12% for methanol for ZEA, T2 and FUM respectively. Inter spotting precision was 4%, 14% and 6% for PBS and 3%, 9% and 16% for methanol for ZEA, T2 and FUM respectively. The feasibility of the nanoarray as an easy to use sensitive screening tool in the 96 well format has been demonstrated for the multiplex detection of three regulated mycotoxins. Improvements in automated image and data analysis software for novice end users are required to improve the overall rapidity of analysis.

Feasibility of a novel multispot nanoarray for antibiotic screening in honey.

Practical solutions for multiple antibiotic determination in food are required by the food industry and regulators for cost-effective screening purposes. This study describes the feasibility in development and preliminary performance of a novel multispot nanoarray for antibiotic screening in honey. Using a multiplex approach, the metabolites of the four main nitrofuran antibiotics, including morpholinomethyl-2-oxazolidone (AMOZ), 3-amino-2-oxazolidinone (AOZ), semicarbazide (SEM), 1-aminohydantoin (AHD) and chloramphenicol (CAP), were simultaneously detected. Antibodies specific to the five antibiotics were nano-spotted onto microtitre plate wells and a direct competitive assay format was employed. The assay characteristics and performance were evaluated for feasibility as a screening tool for antibiotic determination in honey to replace traditional ELISAs. Optimisation of the spotting and assay parameters was undertaken with both individual and multiplex calibration curves generated in PBS and a honey matrix. The limits of detection as determined by the 20% inhibitory concentrations (IC20) were determined as 0.19, 0.83, 0.09, 15.2 and 35.9 ng ml-1 in PBS, 0.34, 0.87, 0.17, 42.1 and 90.7 ng ml-1 in honey (fortified at the start of the extraction), and 0.23, 0.98, 0.24, 24.8 and 58.9 ng ml-1 in honey (fortified at the end of the extraction) for AMOZ, AOZ, CAP, SEM and AHD respectively. This work has demonstrated the potential of multiplex analysis for antibiotics with results available for 40 samples within a 90-min period for antibiotics sharing a common sample preparation. Although both the SEM and AHD assay do not show the required sensitivity with the antibodies available for use to meet regulatory limits, with further improvements in these particular antibodies this multiplex format has the potential to show a reduction in cost with reduced labour time in combination with the high-throughput screening of samples. This is the first 96-well spotted microtitre plate nanoarray for the semi-quantitative and simultaneous analysis of antibiotics.