Improved Discrimination for Brassica Vegetables Treated with Agricultural Fertilizers Using a Combined Chemometric Approach

Abstract

Multielement and stable isotope (δ(13)C, δ(15)N, δ(2)H, δ(18)O, (207)Pb/(206)Pb, and (208)Pb/(206)Pb) analyses were combined to provide a new chemometric approach to improve the discrimination between organic and conventional Brassica vegetable production. Different combinations of organic and conventional fertilizer treatments were used to demonstrate this authentication approach using Brassica chinensis planted in experimental test pots. Stable isotope analyses (δ(15)N and δ(13)C) of B. chinensis using elemental analyzer-isotope ratio mass spectrometry easily distinguished organic and chemical fertilizer treatments. However, for low-level application fertilizer treatments, this dual isotope approach became indistinguishable over time. Using a chemometric approach (combined isotope and elemental approach), organic and chemical fertilizer mixes and low-level applications of synthetic and organic fertilizers were detectable in B. chinensis and their associated soils, improving the detection limit beyond the capacity of individual isotopes or elemental characterization. LDA shows strong promise as an improved method to discriminate genuine organic Brassica vegetables from produce treated with chemical fertilizers and could be used as a robust test for organic produce authentication.

Stable Isotope Effects of Biogas Slurry Applied as an Organic Fertilizer to Rice, Straw, and Soil

“…Acetanilide (Puriss. p.a., Sigma-Aldrich) was used to calibrate elemental % C and % N. Multipoint calibration was applied using reference standard materials including B2155 (protein, δ 13 18 O/ 16 O value of the analytical samples and standards, respectively. The δ i E values are expressed in units "per mil" (‰).…”

“…In previous studies, δ 15 N isotopes have been reported to be a promising indicator for organic fertilization practice due to specific δ 15 N differences between synthetic fertilizers and unfermented animal manures, 11,12 compared to other available stable isotopes such as carbon (δ 13 C), hydrogen (δ 2 H), and oxygen (δ 18 O). Over the last 15 years, many studies have used δ 15 N analyses to discriminate organically and conventionally grown vegetables such as cabbage, 13 tomato, 14 sweet pepper, 15 lettuce, 4 brassica, 16 and a range of market vegetables. 17,18 Previous studies have also reported δ 15 N differences between organic and conventional rice.…”

“…In previous studies, δ 15 N isotopes have been reported to be a promising indicator for organic fertilization practice due to specific δ 15 N differences between synthetic fertilizers and unfermented animal manures, , compared to other available stable isotopes such as carbon (δ 13 C), hydrogen (δ 2 H), and oxygen (δ 18 O). Over the last 15 years, many studies have used δ 15 N analyses to discriminate organically and conventionally grown vegetables such as cabbage, tomato, sweet pepper, lettuce, brassica, and a range of market vegetables. , Previous studies have also reported δ 15 N differences between organic and conventional rice. , Generally, the δ 15 N values of rice are dependent on farming practices, fertilizer type (nitrogen source), and its fractionation according to ammonia volatilization and/or loss of 14 N from the fertilizer . Previous studies suggest that δ 15 N values of rice can be exploited to discriminate rice grown with organic composts or synthetic fertilizers due to specific 15 N uptake response.…”

Long-Term Agricultural Effects on the Authentication Accuracy of Organic, Green, and Conventional Rice Using Isotopic and Elemental Chemometric Analyses

“…In recent years, stable isotopic and multielemental signatures have played an increasingly important role in food forensics and the identification of production methods for plant-derived agroproducts (organic vs green or conventional) based on different fertilization practices. − They have been successfully applied to various studies on vegetables, − tea, cereals, − and fruits. , In particular, the δ 15 N signature is deemed to be the most promising isotopic indicator for differentiating organically farmed crops from conventionally farmed counterparts . Organic farming systems rely on the use of organic fertilizers but exclude synthetic fertilizers produced by the Haber–Bosch process.…”

Análisis de plaguicidas en hortalizas de hojas verdes mediante espectroscopía de plasmas producidos por láser

“…Las técnicas quimométricas, tales como el análisis de componentes principales (PCA) y el análisis discriminante lineal (LDA), son métodos estadísticos multivariados aplicados a: reducción de problemas dimensionales (número de variables), evitando así la pérdida de información esencial; reconocimiento de patrones; y caracterización de un conjunto de muestras Miller and Miller 2002). Aunque las técnicas de análisis quimiométrico multivarial se han aplicado a la clasificación de alimentos (Bilge et al 2015;Markiewicz-Keszycka et al 2018;Yuan et al 2016), actualmente no se informan estudios que implementen LIBS junto con técnicas quimiométricas para la caracterización de plaguicidas en vegetales.…”