Applicability of supercritical fluid chromatography for oligonucleotide analysis: A proof-of-concept study

We evaluated the suitability of supercritical fluid chromatography (SFC) for oligonucleotide analysis using 4-mer oligonucleotides with various phosphorothioate (PS) contents as model compounds. Column screening showed that the diol-modified column was able to separate sequences with different PS contents. Optimization of the column body and additives allowed us to analyze polar oligonucleotides using SFC. Various sequences were also analyzed using the optimized method. A good peak shape was obtained when the guanine plus cytosine content of the analyte was two or less in the 4-mer oligonucleotides. Furthermore, we found that the retention times of the selected sequences were positively correlated with polar surface areas, indicating that oligonucleotides interact with polar stationary phases. In contrast, more hydrophobic full PS sequences were retained more strongly in the diol column than the full phosphodiester (PO) sequences. This suggests that the diol column has unique selectivity for PO and PS linkages. These results indicate that SFC is potentially applicable to oligonucleotide analysis with a separation mechanism that is different from that of ion-pair reversed-phase liquid chromatography.

Advanced Development of Supercritical Fluid Chromatography in Herbal Medicine Analysis

The greatest challenge in the analysis of herbal components lies in their variety and complexity. Therefore, efficient analytical tools for the separation and qualitative and quantitative analysis of multi-components are essential. In recent years, various emerging analytical techniques have offered significant support for complicated component analysis, with breakthroughs in selectivity, sensitivity, and rapid analysis. Among these techniques, supercritical fluid chromatography (SFC) has attracted much attention because of its high column efficiency and environmental protection. SFC can be used to analyze a wide range of compounds, including non-polar and polar compounds, making it a prominent analytical platform. The applicability of SFC for the separation and determination of natural products in herbal medicines is overviewed in this article. The range of applications was expanded through the selection and optimization of stationary phases and mobile phases. We also focus on the two-dimensional SFC analysis. This paper provides new insight into SFC method development for herbal medicine analysis.

A Comparative Study of Milk Fat Extracted from the Milk of Different Goat Breeds in China: Fatty Acids, Triacylglycerols and Thermal and Spectroscopic Characterization

Goat milk (GM) is an excellent alternative to cow milk and has recently been used in commercial infant formula preparation due to its superior fat composition. Here, the fatty acid (FA) composition, triacylglycerol (TAG) molecular species, thermal behavior and infrared spectra of extracted milk fat from the milk of the two main breeds of dairy goat bred in China (Guanzhong GM (GZG) and Xinong Saanen GM (XSG)) are investigated. Gas chromatography, Fourier-transform infrared spectroscopy, differential scanning calorimetry and ultra-performance convergence chromatography with quadrupole time-of-flight mass spectrometry are applied. The obtained results evidence significant fat compositional differences based on the breed that produced the considered GM. The major FAs in both GM fats were capric (C10:0), myristic (C14:0), palmitic (C16:0), stearic (C18:0) and oleic (C18:1 n-9c). GZG presented a higher content of medium-chain saturated FAs, while XSG had higher unsaturated FAs with higher ratios of L/Ln and n-6/n-3. A total of 339 and 359 TAGs were detected and quantified in GZG and XSG, and the major TAGs were those of m/z 740.6712 (14.10 ± 0.27%) and m/z 684.6094 (10.94 ± 0.02%), respectively. Milk TAGs of GZG and XSG showed 24–54 and 26–54 total acyl carbon numbers with a 0–4 and 0–5 double bond number at 68 and 72 various retention times, respectively. Thermal analysis showed that all GM fat samples melted below normal body temperature. Infrared spectra revealed higher absorption values of GZG milk fat. This study provides valuable information to the dairy industry sector about GM fat produced in China, assessing the appropriateness of Chinese GM fat to be applied in Chinese infant formula.

The optimization of ultrasonic-microwave assisted synergistic extraction of Lotus plumule extract rich in flavonoids and its hypoglycemic activity

Lotus (Nelumbo nucifera Gaertn), a kind of perennial aquatic plant, is widely cultivated and consumed by people in Asian countries. Lotus plumule flavonoids (LPF) have been recognized as a hypoglycemic agent. LPF was optimally obtained using novel ultrasonic-microwave assisted synergistic extraction (UMSE) method by response surface methodology (RSM) on the basis of the results of single-factor experiments. Furthermore, the hypoglycemic activity of LPF was investigated by measuring the body weight, fasting blood glucose (FBG) level, and oral glucose tolerance test (OGTT) and analyzing the physiological indexes in streptozotocin-diabetic mice model. The optimum extraction conditions consisted of microwave power 355 W, ultrasonic power 423 W, extraction time 15 min, solid-liquid ratio 1:40, ultrasound/interval time 1/0, and ethanol concentration 70% with the maximum LPF yield of 2.62%. LPF supplementation significantly decreased the body weight, FBG, OGTT, serum total cholesterol (TC), serum total triglycerides (TG), and insulin levels, indicating the antidiabetic activity of LPF. This research verified that the UMSE technique was highly efficient to extract LPF to the maximum extent and the flavonoids from L. plumule exhibited hypoglycemic activity, which showed broad development and application prospects.

Chromatographic Fingerprint Analysis of Radix Hedysari Using Supercritical Fluid Chromatography Coupled with Diode Array Detector

A newly and rapid supercritical fluid chromatography method for the simultaneous determination of 11 active compounds in Radix Hedysari samples has been developed and validated. Optimum separation was achieved on a HSS SB C18 column with a gradient elution at a flow rate of 1.5 mL/min, back pressure of 11.03 Mpa and diode array detector at 260 nm. The results from the quantitative data showed that contents of these 11 active compounds were different from plant regions. Especially the contents of formononetin in the Minxian county are ~6-fold than in wild Radix Hedysari. The chromatographic fingerprint of Radix Hedysari was recorded under the same chromatographic condition. Data analytic procedure was performed to differentiate the 25 batches of Radix Hedysari samples. Data from chromatographic fingerprint were also analyzed using hierarchical cluster analysis. The results showed that 23 batches of Radix Hedysari samples had a high similarity (> 0.90) and overall 25 batches of sample were divided into two clusters. Moreover, according to the comparison contents of active compounds in each Radix Hedysari samples, the cultivated location of Radix Hedysari was successfully distinguished. This method presented good stability, repeatability and precision and would be a useful and reliable approach for the quality control of Radix Hedysari. Moreover, all target compounds were quantified by ultra-high performance liquid chromatography-time-of-flight mass spectrometry.

Comparison of Retention Behavior between Supercritical Fluid Chromatography and Normal-Phase High-Performance Liquid Chromatography with Various Stationary Phases

The retention behavior of a wide variety of stationary phases was compared in supercritical fluid chromatography (SFC) and normal-phase high-performance liquid chromatography (NP-HPLC). We also attempted to elucidate the retention behavior in SFC by investigating the selectivity of the different stationary phases. SFC separation conditions with polar stationary phases, such as silica gel (SL) and diol (Diol) phases, operate via adsorptions that include hydrophilic and ionic interactions similar to those in NP-HPLC. Moreover, non-polar stationary phases, such as pentabromophenyl (PBr), pyrenylethyl (PYE), and octadecyl (C₁₈), could be used despite the non-polar mobile phase conditions, because the dispersion and π-π interactions were stronger in SFC than in HPLC. These results reflect the selectivity of the stationary phase and its retention factor, thus providing useful information for the selection of appropriate stationary phases for particular analytes.

Triacylglycerol compositions of sunflower, corn and soybean oils examined with supercritical CO2 ultra-performance convergence chromatography combined with quadrupole time-of-flight mass spectrometry

A supercritical CO₂ ultra-performance convergence chromatography (UPC²) system was utilized with a quadrupole time-of-flight mass spectrometry (Q-TOF MS) to examine the triacylglycerol compositions of sunflower, corn and soybean oils. UPC² provided an excellent resolution and separation for the triacylglycerols, while the high performance Q-TOF MS system was able to provide the molecular weight and fragment ions information for triacylglycerol compound characterization. A total of 33 triacylglycerols were identified based on their elementary compositions and MS² fragment ion profiles, and their levels in the three oils were estimated. The combination of UPC² and Q-TOF MS may determine triacylglycerol compositions for oils and fats, and provide sn-position information for fatty acids, which may be important for food nutritional value and stability.

Simultaneous determination of 16 polycyclic aromatic hydrocarbons in reclaimed water using solid-phase extraction followed by ultra-performance convergence chromatography with photodiode array detection

A new fast and effective analysis method has been developed to simultaneously determine 16 polycyclic aromatic hydrocarbons in reclaimed water samples by ultra-performance convergence chromatography with photodiode array detection and solid-phase extraction. The parameters of ultra-performance convergence chromatography on the separation behaviors and the crucial condition of solid-phase extraction were investigated systematically. Under optimal conditions, the 16 polycyclic aromatic hydrocarbons could be separated within 4 min. The limits of detection and quantification were in the range of 0.4-4 and 1-10 μg/L in water, respectively. This approach has been applied to a real industrial wastewater treatment plant successfully. The results showed that polycyclic aromatic hydrocarbons were dramatically decreased after chemical treatment procedure, and the oxidation procedure was effective to remove trace polycyclic aromatic hydrocarbons.

Supercritical fluid chromatography with photodiode array detection for pesticide analysis in papaya and avocado samples

To improve the analysis of pesticides in complex food matrices with economic importance, alternative chromatographic techniques, such as supercritical fluid chromatography, can be used. Supercritical fluid chromatography has barely been applied for pesticide analysis in food matrices. In this paper, an analytical method using supercritical fluid chromatography coupled to a photodiode array detection has been established for the first time for the quantification of pesticides in papaya and avocado. The extraction of methyl parathion, atrazine, ametryn, carbofuran, and carbaryl was performed through the quick, easy, cheap, effective, rugged, and safe methodology. The method was validated using papaya and avocado samples. For papaya, the correlation coefficient values were higher than 0.99; limits of detection and quantification ranged from 130-380 and 220-640 μg/kg, respectively; recovery values ranged from 72.8-94.6%; precision was lower than 3%. For avocado, limit of detection values were ˂450 μg/kg; precision was lower than 11%; recoveries ranged from 50.0-94.2%. Method feasibility was tested for lime, banana, mango, and melon samples. Our results demonstrate that the proposed method is applicable to methyl parathion, atrazine, ametryn, and carbaryl, toxics pesticides used worldwide. The methodology presented in this work could be applicable to other fruits.