Romer Labs launches ELISA test to detect Aflatoxin M1
AgraQuant Aflatoxin M1 High Sensitivity allows detection to exceed requirements of existing regulations, said the firm.
The tests are enzyme-linked immunosorbent assays (ELISA) in a quantitative format for a parallel measurement of up to 42 samples.
The kit has a pipetting volume of 100 µl and does not require an agitation step which removes two sources of potential error, said Romer Labs.
There are four principle types of aflatoxin B1, B2, G1 and G2. Aflatoxin M1 is a hydroxylated metabolite of aflatoxin B1.
Matrix validation and target market
It is validated for commodities such as raw milk, fresh milk, UHT milk and several milk powders (full fat, low fat, skim, infant).
Results can be interpreted and documented with a StatFax or BioTek ELISA reader.
US Food and Drug Administration action level is 500ppt for milk. Chinese regulations have a maximum concentration of 500ppt in milk powder for infant food (calculated in dry powder). To test, powder needs to be dissolved in 10ml of water. So the max concentration of aflatoxin M1 in dissolved milk powder is 50ppt. EU regulation has a limit of 0.050ppb for aflatoxin M1 in raw milk, heat treated milk and milk for the manufacture of milk-based products and 0.025ppb for infant formulae and follow-on formulae including infant milk and follow-on milk
Philipp Gruber, product manager, said the test took two and a half years to develop.
“Testing is mostly conducted by the dairy industry at reception points. When truckloads of milk enter the dairy facility, the buyer checks the quality of the incoming goods,” he told FoodQualityNews.
“Testing frequency is variable depending on company and overall aflatoxin occurrence in respective region. If aflatoxin concentration in feed is potentially high, also milk needs to be checked in higher frequency.
“The best way to monitor aflatoxin M1 is to test both aflatoxin B1 in feed that is given to dairy cows and aflatoxin M1 in milk that is produced by respective cows. We have two ELISAs detecting Total Aflatoxin (sum of B1, B2, G1, G2) and one ELISA detecting Aflatoxin B1.”
Target customers include third party labs as well as the dairy and baby food industry, added Gruber.
Analytical sensitivity (LOD) of AgraQuant Aflatoxin M1 HS is 2.9 ppt and the quantitation range is 5-100 ppt.
"The ranges of Romer Labs Aflatoxin M1 detecting ELISAs are designed in order to enable our customers to test according to worldwide mycotoxin regulations. Incubation times of fumonisin, T-2 Toxin, T-2/HT-2 Toxin, DON, ZON, aflatoxin and OTA kits are either 15 or 20 minutes,” said Gruber.
“Overall mycotoxin regulations of EU and US differ. Goods that are imported to EU need to meet European regulations. Exports from US subsequently need to be tested according to EU regulations if their country of destination lies within EU. US dairy products are hardly imported to EU.”
Workflow and sampling importance
The workflow involves pipetting 100 µl of sample or standards into antibody coated wells, incubate at room temperature for 45 minutes, wash five times with diluted wash buffer and tap try washed wells.
Pipette 100 µl conjugate solution into the antibody coated wells and incubate at room temperature for 15 minutes, repeat the washing steps, pipette 100 µl substrate solution into the antibody coated wells and incubate at room temperature for 15 minutes.
Add 100 µl stop solution into the antibody coated wells and read the strip with the ELISA reader using a 450nm filter and 630 nm differential filter.
Gruber said screening methods such as ELISA or lateral flow devices are used because they are cheaper, faster and easier to operate than reference methods.
“Sending samples to a service lab takes about a week until a result received. Screening methods are used to test more samples in a shorter time to get a broader understanding about product quality. Screening results of positive samples usually verified with reference methods,” he said.
“Both ELISA and lateral flow devices are antibody based systems and considered screening methods. Strip tests are designed to give results as soon as possible, though they can only process two samples at a time. They are therefore widely used at reception points of the supply chain of agricultural raw commodities.
“ELISA test kits can test up to 44 samples simultaneously. In general, ELISA is the better option when you have six or more samples.”
Romer Labs said sampling is an important topic when it comes to test for mycotoxins in agricultural raw commodities.
The firm said sampling error accounts for 76% of total error when testing for mycotoxins.
It advised using a finer grind to improve results, consulting the mycotoxin sampling tool on the FAO website and increasing sample number and size as EU recommendations state for up to 50 tons of cereals take 10 to 100 incremental samples of 100g each.