Brown rice: validation and pesticide survey

MEDINA, MARÍA BELÉN; MUNITZ, MARTÍN; RESNIK, SILVIA LILIANA; WILLIMAN, CELIA; PAGE, LUCAS; NOVOA, MARTÍN; COLMAN CASANOVA, DAVID; PIACENZA, MICAELA

Workshop; 8º Edición de Latin American Pesticide Residue Workshop (LAPRW); 2021

Nowadays, the growing concernabout a healthier diet has made brown rice a preference against polished rice,in some households, because of it higher amount of fiber, vitamins andminerals, which are mainly found in its outer layer, known as bran. Both cropsand rice grains can be affected by pests and fungal diseases; which can cause economiclosses, making pesticide application necessary for their control. Pesticides representa problem for food consumers, due to their accumulation in them. For thesereasons, the objectives are to validate an analytical methodology for tracelevels determination of deltamethrin, kresoxim methyl, cyproconazole,epoxiconazole and azoxystrobin in brown rice; and to determine its presence in20 commercial samples. The extractive method used was QuEChERS; analytes weredetermined by gas chromatography with a µECD detector; and confirmed by massspectrometry. Matrix-matched calibration was performed due to the existence ofa matrix effect. The calibration curve was linear in the range of 0.005 to 1.5ppm. The linearity of the method presented a correlation coefficient R2greater than 0.9996, for all pesticides. Precision was evaluated at 3concentration levels, with a relative standard deviation (RSD) lower than 10%for n = 9. Recovery was studied at 3 concentrations in triplicate, with resultsbetween 80% and 102%, in all cases. The detection and quantification limitswere 0.28 and 0.88 µg / kg, 0.25 and 0.77 µg / kg, 0.28 and 0.90 µg / kg, 0.25and 0.75 µg / kg, 0.29 and 0.92 µg / kg, for deltamethrin, kresoxim methyl,cyproconazole, epoxiconazole, and azoxystrobin, respectively. The expandeduncertainty was lower than 20%. After validation, 20 brown rice samples,purchased from different stores, were analyzed. The results indicated that thestudied pesticides were detected in all the analyzed samples. The maximum concentrationswere 31.70 µg / kg, 34.01 µg / kg, 21.58 µg / kg, 163.65 µg / kg and 33.91 µg /kg, for deltamethrin, kresoxim methyl, cyproconazole, epoxiconazole andazoxystrobin, respectively.The Maximum Residue Limits (MRLs) established by theEuropean Union were exceeded for epoxiconazole and kresoxim methyl in 1 and 12samples, respectively; while 19 samples exceeded the MRL established by SENASAfor epoxiconazole. In conclusion, the validated analytical methodology isselective and sensitive, with adequate precision, accuracy and uncertainty,with detection and quantification limits lower than the MRLs established bynational and international legislations, allowing the determination ofdeltamethrin, kresoxim methyl, cyproconazole, epoxiconazole and azoxystrobin inbrown rice.