Analysis of the main conjugated linoleic acid (CLA) precursors (C18:2 n-6 and C18:3 n-3) in Brachiaria ruzizienses by capillary zone electrophoresis

Abstract

An alternative method for extraction optimization of C18:2 n-6 and C18:3 n-3, the main precursors for the synthesis of conjugated linoleic acid (CLA), in Brachiaria ruzizienses forages was proposed. Three methods of lipid extraction were tested: 1. Hara & Radin, 2. Micro Folch and 3. Bligh & Dyer. The preliminary test showed the Hara & Radin method as the most promising procedure. Then, a 33 Box Behnken design with triplicate in the central point was applied in Hara & Radin method in order to optimize the extraction procedure. The optimization extraction was monitored by quantification of C18:2 n-6 and C18:3 n-3 through capillary zone electrophoresis (CZE). The results obtained by CZE were compared to gas chromatography (AOCS official method) in real samples using the paired t-test. No significant difference between methods was found within a 95% confidence interval (p-value= 0.937). The alternative CZE method for Brachiaria ruzizienses forages analysis has some advantages in comparison with official GC method such as, short analysis time (10 min), no derivatization step for sample preparation, absence of specific separation columns, lower analytical cost and high throughput.

Fatty acids analysis by capillary electrophoresis: Fundamentals, advantages and applications

“…Focusing on the use of TSH capillary, combined with the BGE composition of 15 mM NaH 2 PO 4 /Na 2 HPO 4 buffer (pH 7), 4 mM SDBS, 8.3 mM Brij R 35, 45% v/v ACN, and 2.1% v/v 1-octanol, this methodology was applied to determine FAs over the years. Hydrogenated vegetable fat, butter, margarine, and filled cookies [11], pequi fruits [30,34], extra virgin olive oil, virgin olive oil, soybean oil, and biodiesel [11,32,36], forages [29], analysis of FAs in liver rats submitted to a specific diet [31], chocolates [33], milk adulteration [35], and bottled butter [10], have been analyzed by CE, showing the potential of this method for the determination of a range of FAs in challenging samples and different applications. However, some works used the same BGE with TSP capillary for analysis of FAs in olive oil [26], in hydrogenated vegetable fat, and in spreadable processed cheese [27,28], in pumpkin seed oil and moisturizing cream with this oil in its composition [6], in encapsulated vegetable oil supplements [7], and in hops [38].…”

A digest of capillary electrophoretic methods applied to lipid analyzes

“…Additionally, soybean oils were investigated using similar methods . Finally, a comparison of the newly developed and the official GC methods was made , by way of the separation of C18:2 and C18:4 isomers with a minimum amount of MeOH (5–20%) and larger concentrations of surfactants, including SDS, (R)‐N‐dodecoxycarbonylvaline and CD, using direct UV detection . The isomers of C18:3 were also studied under very similar conditions , as were the cis‐trans isomers of linoleic acid .…”

20 Years of Fatty Acid Analysis by Capillary Electrophoresis

“…Ideally, the selected chromophore must have high molar absorptivity at the working wavelength, effective mobility close to the analytes in order to reduce electromigration dispersion and a negative charge [40]. Among the chromophores used for CZE FA analysis under UV-ID, sodium dodecylbenzenesulphonate (SDBS) [28,30,31,41,42,43,44,45] and adenosine monophosphate (AMP) [27,46,47] have been most frequently used. Thus, in general, for the saturated FA analyses, a baseline presents high molar absorptivity, and when the separated FA crosses in front of the detection window, the molar absorptivity decreases and generates a negative peak.…”

“…In this work, the focus of hydrogenation was a concern for the separation of cis-trans isomers present in processed foods. Later, this same BGE, after some optimisation was successfully applied to the analysis of food, fodder and biological samples [28,30,42,44,54,55].…”

“…Alternative methodologies such as Fourier-Transform Infrared (FTIR) [21], attenuated total reflection infrared spectroscopy (ATR-IR) [22,23], silver ion high performance liquid chromatography (Ag + -HPLC) [24,25], gas chromatography coupled with mass detector (GC-MS) [26], and capillary electrophoresis (CE) [27,28,29,30,31] have also been used. These methodologies sometimes offer short analysis time (CE, ATR-IR and FTIR), a non-destructive approach (ATR-IR and FTIR) and simplicity in the sample preparation step (CE, ATR-IR and FTIR), all of which are an advantage in comparison with the classical methodology.…”