In-house method validation, estimating measurement uncertainty and the occurrence of fumonisin B1 in samples of Brazilian commercial rice

- Fumonisin B1 was investigated in commercial rice intended for human consumption.
- The method performance criteria were assessed for three different rice matrices.
- Measurement uncertainty was estimated on the basis of intralaboratory validation data.
- Matrix-matched calibration curves were used for matrix effects compensation.
- A low incidence and a low level of fumonisin B1 were observed in rice samples.

Fumonisin B1 was investigated in samples of rice intended for human consumption, including polished parboiled rice, whole grain rice and whole grain parboiled rice. Until the present, no studies on the occurrence of fumonisin B1 have been performed on these types of rice that are commercially available in the south-eastern region of Brazil. A careful intralaboratory validation was carried out to demonstrate the fitness-of-purpose of the applied method for determining fumonisin B1 in the three studied rice types. The performance criteria - selectivity, reliable limits of detection (50 μg kg−1) and quantification (100 μg kg−1), linearity (range 100-2500 μg kg−1), precision (RSD values ≤ 17.0%) and recovery (71.7-112.0 %) were evaluated, and the expanded measurement uncertainty was estimated by using the data obtained from precision and recovery experiments. Matrix-matched calibration standards were employed to quantify the mycotoxin levels in the rice samples, in which the residual normality, homoscedasticity and independence were confirmed. In addition, the measurement uncertainty values are consistent with the maximum acceptable uncertainty established by European Union regulation for analytical methods for controlling mycotoxins in foodstuffs. Among the thirty-one commercial samples of rice analysed in the present study, five samples presented detectable levels of the mycotoxin, and these levels ranged from 64.8 to 163.0 μg kg−1.