Contents lists available at ScienceDirect Talanta journal homepage: www.elsevier.com/locate/talanta A new and feasible analytical method using reversed-phase dispersive liquid-liquid microextraction (RP-DLLME) for further determination of Nickel in hydrogenated vegetable fat Daneysa Lahis Kalschne a , Cristiane Canan a , Murilo Oliveira Beato b , Oldair Donizete Leite b , Eder Lisandro Moraes Flores b,∗ a Departamento de Alimentos, Universidade Tecnológica Federal do Paraná, Avenida Brasil, 4232, Bairro Independência, 85884-000, Medianeira, PR, Brazil b Departamento de Química, Universidade Tecnológica Federal do Paraná, Avenida Brasil, 4232, Bairro Independência, 85884-000, Medianeira, PR, Brazil ARTICLEINFO Keywords: Dispersive liquid-liquid microextraction Sample preparation Hydrogenated vegetable fat Atomic absorption spectrometry Preconcentration ABSTRACT A new and simple method for Ni determination in hydrogenated vegetable fat (HVF) has been developed using a RP-DLLME sample preparation procedure for further determination by fame atomic absorption spectrometry (FAAS) and graphite furnace atomic absorption spectrophotometry (GFAAS). The RP-DLLME procedure includes simultaneous microextraction and preconcentration of Ni in HVF, using 5.0 g of HVF preheated (75 °C) and diluted in 5.0 mL of xylene, with the addition of a dispersant/extractant mixture (n-propanol/dilute HNO 3 ). The sample was manually stirred and centrifuged and the aqueous phase was collected for further Ni determination by FAAS and GFAAS. RP-DLLME was carried out using only 700 μL of n-propanol and 300 μL of 2.0 mol L −1 HNO 3 . The recovery varied from 93.3% to 101.5% for HVF. The LODs and LOQs were 40 and 90 ng g −1 for FAAS, and 0.41 and 1.36 ngg −1 for GFAAS. The proposed analytical method is viable and this is the frst appli- cation of RP-DLLME to solid fat samples, with Ni determination as an example of application. This method consumes small amounts of reagents, with lower toxicity as compared to microwave decomposition. Furthermore, the key features of the RP-DLLME method include simplicity of operation, high sample mass, reduced reagent consumption, and use of diluted HNO 3 as an extractant. 1. Introduction Nickel is widely distributed in the environment, including soil, water and air, but generally in very low concentrations [1]. In small doses, Ni can be associated with some benefts for animal and plant nutrition. However, when the human body is exposed to high levels of Ni it can result in serious health problems, including damage to mucous membranes, changes in chromosomes and marrow, or development of cancer cells. Food or contact allergy are the most common side efects resulting from overexposure to Ni. [2]. Hydrogenated vegetable fat (HVF), which is used in the preparation of various foods, is obtained by the catalytic hydrogenation of vegetable oils. Nickel is the most commonly used catalyst mainly owing to its low cost and good performance [3]. Chinese legislation stipulates a Ni limit of1.0μgg −1 in hydrogenated products [4]. In general, animal and vegetable fat samples are regarded as com- plex matrices to be decomposed for further metal determination [5]. Conventional procedures require the use of concentrated acids, high pressures, and high temperatures for the sample decomposition [6–8]. In previously proposed methods, food products such as hydrogenated vegetable oils, HVF, and margarines were decomposed using closed- vessel system and microwave-assisted decomposition, and Ni determi- nation was achieved by graphite furnace atomic absorption spectro- photometry (GFAAS) or inductively coupled plasma mass spectrometry (ICP-MS) [3,6–8]. Some disadvantages of microwave decomposition include the use of concentrated acids – which requires sample dilution to<10% HNO 3 (v/v) for further determination by atomic spectro- metric techniques [9] - and low sample mass (< 0.5 g) [3,6–8]. Both of these disadvantages imply an increase in the limit of detection (LOD) and limit of quantifcation (LOQ) [3,6,7], except in cases where an additional preconcentration step is employed after the sample decom- position [8]. However, modern instrumentation and a better under- standing of the mechanisms associated with sample decomposition have allowed for high decomposition efciency to be achieved even https://doi.org/10.1016/j.talanta.2019.120409 Received 24 July 2019; Received in revised form 17 September 2019; Accepted 28 September 2019 ∗ Corresponding author. E-mail address: eder@utfpr.edu.br (E.L. Moraes Flores). daneysa@hotmail.com (D.L. Kalschne), canan@utfpr.edu.br (C. Canan), murilooliveirabeato@gmail.com (M.O. Beato), oldairleite@utfpr.edu.br (O.D. Leite) Talanta 208 (2020) 120409 Available online 03 October 2019 0039-9140/ © 2019 Published by Elsevier B.V. T