Revealing full chemical forms of lead in wine with combined XRF-NMR technologies

¹ Consejo Nacional de Ciencia y Tecnología-Laboratorio Nacional de Investigación y Servicio Agroalimentario y Forestal. Universidad Autónoma Chapingo. Carretera México-Texcoco Km 38.5, C.P. 56230, Chapingo, Estado de México, Mexico
² Dirección de Insumos para la Producción – Secretaría Administrativa del Fondo Sectorial CONACyT – SAGAPRA. Secretaría de Agricultura, Ganadería Desarrollo Rural, Pesca y Alimentación. Municipio Libre 377, piso 10 “A”, Col. Santa Cruz Atoyac, C.P, 03310, Ciudad de México, Mexico
³ Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional. Prolongación de Carpio y Plan de Ayala s/n, Colonia Santo Tomás, 11340 Ciudad de México., Mexico
⁴ Consejo Mexicano Vitivinícola A.C. Montecito No 38 Piso 15 Despacho 22 – WTC México, C.P. 03810, Ciudad de México, Mexico
⁵ Laboratorio Nacional de Investigación y Servicio Agroalimentario y Forestal. Universidad Autónoma Chapingo. Carretera México-Texcoco Km 38.5, C.P. 56230, Chapingo, Estado de México, Mexico
⁶ Laboratorio de Análisis Químicos, Instituto Mexicano del Petróleo. Eje Central Lázaro Cárdenas Norte 152, Col. San Bartolo Atepehuacan, Delegación Gustavo A. Madero, C.P. 07730 Ciudad de México, Mexico
⁷ Casa Madero. Carretera Paila 102- Parras Km. 18.2; Hacienda San Lorenzo. Parras de la Fuente. C.P. 27980, Coahuila, Mexico
⁸ Monte Xanic. Lago Tangañica No. 18, Colonia Granada, Municipio Miguel Hidalgo, CP 11520, Ciudad de México, Mexico
⁹ Consejo Viticultores del Estado de Aguascalientes. Merlo 4, Quintas de Monticello, Jesús María, Aguascalientes. CP 20908, Mexico

Abstract

Since 1953, The World Organization of Vine and Wine (OIV) Member States have reduced the lead maximum limits (ML) in wines, down to 0.05 mg/L (2018). Evidently, this ML value is too restrictive for wine industry as it excludes from international market a significant portion of wine production. Currently, the Codex Committee on Contaminants in Foods and OIV had recognized the value of gathering robust and novel data to better assess the best lowest ML for wine industry. Currently, there is not a direct statement within international reference documents, of which chemical form of lead must be controlled and/ or reduced. This work presents for the first time a method combining Energy Dispersive X-Ray analysis (EDAX) and Nuclear Magnetic Resonance (NMR) spectroscopies in order to determine presence and concentrations of major and trace elements of lead and other element moieties in wine that can allow to better redefine lead's ML. By identification of K, L, M, radiation shells with additional αβi labelling of lead's major and minor components with semi-quantitative XRF, combined with chemical-shift analysis of inorganic Pb⁴⁺, Pb²⁺ and/or organo-lead within wine samples, we propose a full discrimination framework to disentangle and quantify different chemical forms of lead.