Evaluating the Performance of Lateral Flow Devices for Total Aflatoxins with Special Emphasis on Their Robustness under Sub-Saharan Conditions

Abstract

As aflatoxins are a global risk for humans and animals, testing methods for rapid on-site screening are increasingly needed alongside the standard analytical laboratory tools. In the presented study, lateral flow devices (LFDs) for rapid total aflatoxin screening were thoroughly investigated with respect to their matrix effects, cross-reactivity, their performance under harsh conditions in Sub-Saharan Africa (SSA), and their stability, as well as when compared with liquid chromatography-tandem mass spectrometry (LC-MS/MS). To analyze the matrix effects, qualitative test kits offering a certain cutoff level were used to screen different nut samples. In addition, these tests were challenged on their cross-reactivity with 230 fungal toxins and metabolites. Furthermore, the resulting measurements performed under harsh tropical conditions (up to 38.4 °C and 91% relative humidity) in SSA, specifically Burkina Faso and Mozambique, were compared with the results from a well-established and validated LC-MS/MS-based reference method. The comparison of the on-site LFD results with the reference method showed a good agreement: 86.4% agreement, 11.8% non-agreement, and 1.8% invalid test results. To test the robustness of the cutoff tests, short- and long-term stability testing was carried out in Mozambique and Nigeria. For both experiments, no loss of test performance could be determined. Finally, a subset of African corn samples was shipped to Austria and analyzed under laboratory conditions using semiquantitative aflatoxin tests. A good correlation was found between the rapid strip tests and the LC-MS/MS reference method. Overall, the evaluated LFDs showed satisfying results regarding their cross-reactivity, matrix effects, stability, and robustness.

Verification of the Accuscan gold reader and RIDA smart phone application rapid test kits in detection and quantification of aflatoxin levels in maize from selected regions in Kenya

“…In the study, the RIDA smart phone application correlation coefficient was average in aflatoxin analysis. In Cvak et al (2021), it is described that during analysis when the maize flour is not well refined during grinding, spot and cross contamination while handling maize samples, analysing samples with temperature of above 30 o centigrade, when using lateral flow disks results are affected. The validation of Reveal Q+ MAX for aflatoxin testing with Accuscan gold reader was done by Le et al (2019) who confirmed that the machine was adequate in detection and quantification of mycotoxins.…”

Stability of the COVID-19 At-Home Test after Exposure to Extreme Temperatures

“…However, short-term (up to 16 h) storage before testing with the Panbio COVID-19 Ag Rapid Test Device (Abbott) at extreme temperatures (freezing at −4.0 to 113.0°F [−20.0 to 45.0°C]) did not impact sensitivity or specificity ( 7 ). Cvak et al ( 8 ) have also reported that an aflatoxin LFT maintained performance in Sub-Saharan conditions (≤101.1°F [≤38.4°C], ≤91% relative humidity) at 3 cutoffs throughout a 5-month study period. Focusing on device design, Kaur et al 2021 ( 9 ) evaluated the effects of long-term storage on the nitrocellulose membranes used in LFTs, finding that lateral rates of membranes in sealed packaging were significantly reduced at temperatures of 99°F (37°C) and 113°F (45°C) after 2 months of storage, which concurs with the reduced sensitivity described above.…”

Developments in mycotoxin analysis: an update for 2021-22

“…While the main innovations deal with the detection platforms, sample extraction procedures are still 'traditional' and no steps forward in aqueous-based 'green' protocols have been reported so far. Cvak et al (2021) reported on a comprehensive study to evaluate the fitness for purpose of commercially available qualitative LFIA (cut off levels of 4 µg/kg, 10 µg/kg, and 20 µg/kg defined by the LFIA manufacturer) for on-site analysis of aflatoxins under Sub-Saharan conditions. First, matrix effects were evaluated by screening different nut samples: no false negative results were obtained, and overall the matrix type had a slight influence on the cut off values of the tests.…”