A Review of Advanced Methods for the Quantitative Analysis of Single Component Oil in Edible Oil Blends.

Edible oil blends are composed of two or more edible oils in varying proportions, which can ensure nutritional balance compared to oils comprising a single component oil. In view of their economical and nutritional benefits, quantitative analysis of the component oils in edible oil blends is necessary to ensure the rights and interests of consumers and maintain fairness in the edible oil market. Chemometrics combined with modern analytical instruments has become a main analytical technology for the quantitative analysis of edible oil blends. This review summarizes the different oil blend design methods, instrumental techniques and chemometric methods for conducting single component oil quantification in edible oil blends. The aim is to classify and compare the existing analytical techniques to highlight suitable and promising determination methods in this field.

Electromagnetic dispersive solid-phase extraction based on polyaniline-coated magnetite/silica materials for the determination of Sudan red I in drinks.

By replacing the permanent magnet with an electromagnet, traditional magnetic solid-phase extraction was developed into electromagnetic dispersive solid-phase extraction. A simple operation of power on and off can realize the separation of adsorbents from solutions easily. The improvement makes it possible for the automation of the determination of Sudan Red I by high-performance liquid chromatography. After series of optimization, a trace amount of Sudan red I was well-determined, and excellent linearity was achieved in the range of 0.005 to 1 mg/L with the correlation coefficient (R2 ) = 0.997. The limit of detection with a signal-to-noise ratio of 3 was found to be 0.001 mg/L. The spiked recoveries of Sudan red I for the samples ranged from 93.6 to 104.9%. Moreover, the adsorbent could be recycled at least ten times. The results show that the electromagnetic dispersive solid-phase extraction combined with high-performance liquid chromatography is a rapid, eco-friendly, effective, and sensitive determination method with fascinating automation potential and high practical applicability.

Weighted multiscale support vector regression for fast quantification of vegetable oils in edible blend oil by ultraviolet-visible spectroscopy.

Weighted multiscale support vector regression combined with ultraviolet-visible (UV-Vis) spectra for quantitative analysis of edible blend oil is proposed. In the approach, UV-Vis spectra of the training set are decomposed into a certain number of intrinsic mode functions (IMFs) and a residue by empirical mode decomposition (EMD) at first. Then support vector regression (SVR) sub-models are built on each IMF and residue. For prediction set, the spectra are decomposed as done on the training set and the final predictions are obtained by integrating SVR sub-model predictions by weighted average. The weight of the sub-model is the reciprocal of the fourth power of the root mean square error of cross-validation (RMSECV). For predicting peanut oil in binary blend oil and sesame oil in ternary blend oil, the proposed method has superiority in root mean square error of prediction (RMSEP) and correlation coefficient (R) compared with SVR and partial least squares (PLS).

Robust boosting neural networks with random weights for multivariate calibration of complex samples.

Neural networks with random weights (NNRW) has been used for regression due to its excellent performance. However, NNRW is sensitive to outliers and unstable to some extent in dealing with the real-world complex samples. To overcome these drawbacks, a new method called robust boosting NNRW (RBNNRW) is proposed by integrating a robust version of boosting with NNRW. The method builds a large number of NNRW sub-models sequentially by robustly reweighted sampling from the original training set and then aggregates these predictions by weighted median. The performance of RBNNRW is tested with three spectral datasets of wheat, light gas oil and diesel fuel samples. As comparisons to RBNNRW, the conventional PLS, NNRW and boosting NNRW (BNNRW) have also been investigated. The results demonstrate that the introduction of robust boosting greatly enhances the stability and accuracy of NNRW. Moreover, RBNNRW is superior to BNNRW particularly when outliers exist.

Simultaneous spectrophotometric determination of trace copper, nickel, and cobalt ions in water samples using solid phase extraction coupled with partial least squares approaches.

A simultaneous spectrophotometric determination method for trace heavy metal ions based on solid-phase extraction coupled with partial least squares approaches was developed. In the proposed method, trace metal ions in aqueous samples were adsorbed by cation exchange fibers and desorbed by acidic solution from the fibers. After the ion preconcentration process, the enriched solution was detected by ultraviolet and visible spectrophotometer (UV-Vis). Then, the concentration of heavy metal ions were quantified by analyzing ultraviolet and visible spectrum with the help of partial least squares (PLS) approaches. Under the optimal conditions of operation time, flow rate and detection parameters, the overlapped absorption peaks of mixed ions were obtained. The experimental data showed that the concentration, which can be calculated through chemometrics method, of each metal ion increased significantly. The heavy metal ions can be enriched more than 80-fold. The limits of detection (LOD) for the target analytes of copper ions (Cu2+), cobalt ions (Co2+) and nickel ions (Ni2+) mixture was 0.10µgL-1, 0.15µgL-1 and 0.13µgL-1, respectively. The relative standard deviations (RSD) were less than 5%. The performance of the solid-phase extraction can enrich the ions efficiently and the combined method of spectrophotometric detection and PLS can evaluate the ions concentration accurately. The work proposed here is an interesting and promising attempt for the trace ions determination in water samples and will have much more applied field.

High-Throughput Determination of Octanol-Water Partition Coefficients by Ultrasound-Assisted Liquid-Phase Microextraction.

A method of high-throughput determination, which is based on ultrasound-assisted liquid-phase microextraction, was developed to measure directly the partition coefficients of n-octanol-water. In ultrasound-assisted liquid-phase microextraction, ultrasonic energy can facilitate the mass transfer process of six or more microextractors simultaneously. Therefore, high-throughput determination of n-octanol-water partition coefficients can be performed favorably, and the equilibrium time of each microextractor can be decreased effectively. Several experimental parameters including ultrasonic power and frequency, centrifugation conditions, extractant volume and sample concentration were analyzed and optimized at 25°C. Under the optimum conditions, it only takes 2 min to reach extraction equilibrium, and the solutions of sample can be separated by centrifugation in 4 min. After centrifugation, the concentrations in n-octanol phases are analyzed with gas chromatography. The method was further evaluated with eight reference compounds and the findings demonstrated that this method is suitable to determine the partition coefficients of organic compounds accurately and quickly. Next, the method was exploited to measure the partition coefficients of n-octanol-water containing 20 organic compounds, which cover the [Formula: see text] values from 0.05 to 4.36, with comparatively low relative standard deviation (RSD) directly. The results of this study illustrated that the RSD (n = 6) was under 3%.

High-throughput determination of nicotine in plasma by ultrasonication enhanced hollow fiber liquid-phase microextraction prior to gas chromatography.

In high-throughput ultrasonication enhanced hollow-fiber liquid-phase microextraction (H-U-HF-LPME), ultrasonication was introduced into HF-LPME to enhance the mass transfer rate of the analytes in the two immiscible liquid phases, which resulted in a very short time for extraction equilibrium and a high-throughput analysis. Several parameters were investigated and optimized (such as extraction solvent, temperature of sample, frequency and intensity of ultrasonication, volume of extractant, extraction time, ionic strength of the sample and sample concentration). Based on the results of this study, nicotine was first extracted from a 1.5 mL sample solution under the optimum conditions (ultrasonic power of 50 W with a frequency of 60 kHz, extraction time of 10 min, sodium chloride concentration of 5 mol/L and temperature of 37°C). Next, 0.5 µL of acceptor solution inside the hollow fiber was automatically injected into a gas chromatograph with a flame ionization detector. The results of this study illustrated that the limit of detection, relative standard deviation (n = 6), relative recovery and enrichment factor of nicotine were 0.06 µg/L, 3%, 99.8% and 16.6, respectively. Finally, H-U-HF-LPME was successfully applied for the determination of nicotine in plasma.

Determination of trace benzene derivatives in aqueous samples by ultrasonic enhanced hollow fiber liquid-phase microextraction prior to gas chromatography.

A new method was developed for the determination of trace compounds in water samples using ultrasonic-enhanced hollow fiber liquid-phase microextraction (U-HF-LPME). The ultrasonic radiation, which produces mechanical vibration and ultrasonic cavitation, could be used for accelerating the diffusion mass transfer process. Thus, ultrasonic was introduced into the HF-LPME procedure to enhance the mass-transfer rate during the aqueous and extraction solvent phases. Experimental parameters such as the extraction solvent, the extraction time, the ultrasonic frequency and power, the extractant volume, and ionic strength of the sample were assessed and optimized. Under optimal conditions, HF-LPME was achieved within 10 min. The high enrichment factor in the range of 120-666 and a good relative recovery in the range of 97-103% were evaluated with the relative standard deviations (RSDs, n = 5) of 0.3-7.0%. The limit of detection was in the range of 0.8-3.0 µg/L. The method was applied to the analysis of groundwater, lake water, and seawater. The results showed that the method can determine trace benzene derivatives in real samples with RSD values of 1.1-4.2%. The results demonstrated that U-HF- LPME is a rapid, accurate, and effective sample preparation method, and could be successfully applied for the determination of trace compounds in analytical chemistry.

Zone electrophoresis in an inner-cooling wide-bore electrophoresis system with UV detection.

A novel, high-performance wide-bore electrophoresis (WE) system with inner-cooling has been developed. By introducing the mode of a shell and tube heat exchanger into this system to remove Joule heat generated during electrophoresis, it is feasible to extend electrophoresis from the conventional capillary (i.d. <100 microm) to a wide-bore tube (i.d. >1000 microm). The wide tube allows the loading of over 1.0 microL of the sample with an LOD of 3.0 x 10(-4) mg/mL (signal-to-noise ratio, 3:1). Satisfactory separations of model compounds have been achieved on the WE system.

Separation of aromatic acids by wide-bore electrophoresis with nanoparticles prepared by electrospray as pseudostationary phase.

A model mixture of six aromatic acids has been separated using a laboratory-made wide-bore electrophoretic device with aminopropyl-modified nanoparticles used as pseudostationary phase. Optimization of preparation of nanoparticles by an electrospray (ES) method is described. With the optimized electrophoretic method, 30 mmol/L acetate running buffer, pH 4.5, containing 1.0 mg/mL of nanoparticles as an additive was used, and 3.0 kV applied potential, improved resolution was achieved. The average theoretical plate number obtained was above 5.0 x 10(4) theoretical plates per meter with the highest value achieved in certain runs exceeding 1.0 x 10(5) theoretical plates per meter, which was better than previously reported results (approximately 6.7 x 10(4) theoretical plates per meter). Furthermore, repeatabilities of 2, 6.5, and 6% were obtained for the migration time, peak areas, and peak height, respectively. Additionally, sample capacity and sensitivity were improved by hundredfold using the novel wide-bore electrophoresis system compared to traditional CE.

Wide-bore monolithic column for electrochromatography.

A new wide-bore electrophoresis (WE) system adopting an inner cooling device was set up to perform electrochromatography. In this system, a quartz tube of 1.2 mm inner diameter was used as the separation channel. The Joule heat generated during electrophoresis was removed timely through the outer surface of the quartz tube and a cooling capillary inserted into the quartz tube. A proper coolant passed through the cooling capillary to further improve the cooling efficiency. In the primary research, a polyacrylamide monolithic column was successfully prepared in this quartz tube. Then it was evaluated in the electrochromatographic mode. An electric field strength as high as 625 V/cm can be applied to this system without obvious deviation of the current from the linear curve of the Ohm plot. Sample volume as high as 1 microL was injected into the WE system and reasonable efficiency was obtained for separation of the test compounds.