Department of Analytical Chemistry, Nutrition and Food Science, University of Alicante, P.O. Box 99, 03080, Alicante, Spain.
Department of Analytical Chemistry, Nutrition and Food Science, University of Alicante, P.O. Box 99, 03080, Alicante, Spain.
Anal Chim Acta. 2020 Jan 15;1094:34-46. doi: 10.1016/j.aca.2019.10.009. Epub 2019 Oct 9.
This report presents a study on the determination of total polyphenols together with metals in several samples of olive oil produced in Spain. The results provided by applying a conventional extraction method were compared against those encountered by means of the so-called Dispersive Liquid-Liquid Aerosol Phase Extraction method. The novel method is based on the dispersion of the extracting solution in the sample. To accomplish this, an aerosol is pneumatically generated and directed against the surface of the oil sample. The aerosol was generated in order to increase as much as possible the surface area of the interface between the two involved non-miscible phases. As a result, the partition equilibrium was quickly achieved. The critical variables dictating the characteristics of the obtained aerosols as well as those influencing the partition equilibrium state were studied. With the aerosol phase extraction method, the values corresponding to the total polyphenols and metals in real samples were not statistically different as compared to those obtained by the conventional liquid - liquid extraction method. The new method provided shorter extraction times and lower mass of consumed reagents than the conventional one, thus giving rise to a more environmentally friendly method. For polyphenols, calculated limits of detection and quantification were 0.48 and 1.5 mg of gallic acid kg, respectively. The absorbance linearity, in turn, was kept from 0 to 50 mg kg (R = 0.998). In the case of metal and metalloid quantification, the limits of detection found with a sample digestion method ranged from 1.3 (Cu) to 291 (Na) ng mL. Meanwhile, because of the lower dilution factor, this parameter was one order of magnitude lower when these elements were extracted according to the new method. The new extraction method was applied to the analysis of 42 extra virgin olive oils both bottled and directly collected from the oil press, containing single cultivars or blends and produced from different areas. Fresh oils were analyzed and a preliminary study on the oil thermal degradation was also done. Dispersing the extracting solution as an aerosol into the sample can be considered a versatile method able to provide extensive oil chemical information in a rapid way what is especially important in the case of polyphenols.
本报告研究了几种在西班牙生产的橄榄油中总多酚和金属的测定。将常规提取方法的结果与所谓的分散液相气溶胶萃取方法的结果进行了比较。新方法基于将提取溶液分散在样品中。为此，气溶胶被气动生成并指向油样表面。气溶胶的生成是为了尽可能增加两个不混溶相之间的界面表面积。结果，快速达到了分配平衡。研究了决定所得气溶胶特性的关键变量以及影响分配平衡状态的变量。与传统的液-液萃取方法相比，使用气溶胶萃取法，实际样品中总多酚和金属的对应值在统计学上没有差异。与传统方法相比，新方法提供了更短的提取时间和更少的试剂消耗，从而产生了更环保的方法。对于多酚，计算出的检测限和定量限分别为 0.48 和 1.5mg 没食子酸 kg。吸光度线性度则保持在 0 至 50mgkg（R=0.998）。在金属和类金属定量方面，使用样品消解法发现的检测限范围为 1.3（Cu）至 291（Na）ngmL。同时，由于稀释因子较低，当根据新方法提取这些元素时，该参数低一个数量级。该新的萃取方法被应用于分析 42 种特级初榨橄榄油，这些橄榄油有瓶装的，也有直接从榨油机收集的，有单一品种的，也有混合品种的，来自不同地区。对新鲜油进行了分析，并对油的热降解进行了初步研究。将提取溶液分散为气溶胶并进入样品可以被认为是一种通用的方法，能够快速提供广泛的油化学信息，这在多酚的情况下尤为重要。
