Interference-free determination of Sudan dyes in chilli foods using second-order calibration algorithms coupled with HPLC-DAD

This paper presents a new method for the determination of Sudan dyes contained in hot chilli samples. The method employs second-order calibration algorithms to handle the recorded data. The second-order calibration algorithms are based on the popular parallel factor analysis (PARAFAC), alternating trilinear decomposition (ATLD) and self-weighted alternating trilinear decomposition (SWATLD), respectively. These chemometric methodologies have the second-order advantage, which is the ability to get accurate concentration estimates of interested analytes even in the presence of uncalibrated interfering components. The results on a set of spiked chilli test shows that low contents of Sudan I and Sudan II in complex chilli mixtures can be accurately determined using the new method. The sample preparation was based on solvent extraction, and internal standard was not required. Quantification was carried out with simple mobile phase.     

Determination of Cytotoxic Activity of Selected Isoquinoline Alkaloids and Plant Extracts Obtained from Various Parts of Mahonia aquifolium Collected in Various Vegetation Seasons

Melanoma is a serious form of skin cancer that begins in cells known as melanocytes. While it is less common than the other forms of skin cancer, melanoma is more dangerous because of its ability to spread to other organs more rapidly if it is not treated at an early stage. The number of people diagnosed with melanoma has increased over the last few decades. The most widely used treatments include surgery, chemotherapy, and radiation therapy. The search for new drugs to treat various cancers is one of the most important challenges of modern scientific research. Some isoquinoline alkaloids found in different plant species have strong cytotoxic effects on various cancer cells. We tested the effect of isoquinoline alkaloids and extracts obtained from various parts of Mahonia aquifolium collected in various vegetation seasons on human melanoma cancer cells and our data indicated that investigated extract induced significant reduction in cell viability of Human malignant melanoma cells (A375), human Caucasian malignant melanoma cell line (G361), and human malignant melanoma cell line (SKMEL3 cancer cell lines in a dose- and time-dependent manner. Differences in cytotoxic activity were observed for extracts obtained from various parts of Mahonia aquifolium. Significant differences were also obtained in the alkaloids content and cytotoxic activity of the extracts depending on the season of collection of plant material. Our investigations exhibit that these plant extracts can be recommended for further in vivo experiments in order to confirm the possibility of their use in the treatment of human melanomas.     

高效液相色谱-二极管阵列检测法测定小麦粉及面粉改良剂中福美双

福美双是重要的二硫代氨基甲酸酯(DTC)杀菌剂,在小麦中使用限量以1 mg/kg二硫化碳(CS₂)计。目前我国相关检测方法是针对二硫代氨基甲酸酯一类的化合物,二硫代氨基甲酸酯通过与酸反应生成CS₂,采用光谱法或色谱法测定CS₂,间接实现二硫代氨基甲酸酯测定。该方法无法特异性实现对福美双的检测,因此开展小麦粉中福美双检测方法的研究具有重要意义。研究建立了高效液相色谱-二极管阵列检测(HPLC-DAD)测定小麦粉及面粉改良剂中福美双的分析方法。小麦粉及面粉改良剂样品用乙腈溶剂提取后,经涡旋、振荡、冰水浴超声和静置后取上清液过滤,供高效液相色谱测定。采用ZORBAX plus-C18色谱柱(150 mm×4.6 mm, 5 μm)分离,以水-乙腈为流动相洗脱分析,在波长280 nm下检测。实验优化了提取溶剂及其体积、振荡超声条件、色谱柱、检测波长、流动相等条件。该方法采用保留时间和紫外光谱图定性,外标法定量。该方法在线性范围内(0.30~30.0 μg/mL)线性关系良好,相关系数(r²)为0.99999。对小麦粉及面粉改良剂进行1.5、3.0、15 mg/kg 3个水平的加标回收试验,福美双的回收率为89.6%~98.3%,相对标准偏差为1.6%~3.9%(n=6)。方法的检出限和定量限分别为0.5 mg/kg和1.5 mg/kg。该方法采用溶剂提取,操作简单,分析时间短,特异性好,具有精密度高、重复性好、检出限低等特点,适用于小麦粉及面粉改良剂中福美双快速、准确的定量检测。     

HPLC-DAD分析金线莲中天麻素和天麻苷元

研究超声-微波协同法提取金线莲中的天麻素和天麻苷元,并对提取条件进行了优化.应用高效液相-二极管阵列检测法分析提取物中的天麻素和天麻苷元.研究结果表明:金线莲中天麻素、天麻苷元和其他杂质成分能够很好的分离,且两者的含量分别为1.430及0.562 mg/g,相对标准偏差为0.94%和0.25%.方法准确、快速、灵敏度高、重现性好.     

Hypericin and Pseudohypericin. Purity Criteria and Quantitative Determination in Extracts of Saint John’s Wort (Hypericum perforatum)

Summary. Hypericin and pseudohypericin in extracts of St. Johns Wort (Hypericum perforatum) are assayed using UV-Vis, measuring the absorbance at 588nm of a methanolic solution of the compounds. The value of the absorption coefficient is difficult to define insofar as none of the routine purity criteria can be applied to these two compounds. Analysis of the entire UV-Vis spectrum from 220 to 740nm would seem to be a reliable way of comparing different samples. A UV-Vis spectrum was recorded for each of the compounds using a Photodiode array detection system. A more accurate way of determining the levels of hypericin and pseudohypericin in extracts of St. Johns Wort using these reference spectra is described.     

Optimization of matrix solid-phase dispersion extraction method for the analysis of isoflavones in Trifolium pratense

A method based on matrix solid-phase dispersion (MSPD) has been developed for the determination of 12 isoflavones in Trifolium pratense L. Dried leaf samples were blended with C₁₈, placed in small columns and isoflavones extracted with dichloromethane–methanol. Analyses were performed by high performance liquid chromatography with diode array detection (HPLC-DAD) with 2-methoxyflavone as internal standard. Several dispersants, eluents and clean-up steps were tested during the optimization of the process in order to obtain the best selectivity and yields. Mean recoveries ranged from 70% to 119%, with relative standard deviations <18%. The limits of detection were between 0.006 mg/l for biochanin A and 0.108 mg/l for daidzin. The performance of the optimized method in real samples was compared with a conventional method based in solid–liquid extraction (SLE).     

Quantitative analysis of levodopa, carbidopa and methyldopa in human plasma samples using HPLC-DAD combined with second-order calibration based on alternating trilinear decomposition algorithm

An HPLC method combined with second-order calibration based on alternating trilinear decomposition (ATLD) algorithm has been developed for the quantitative analysis of levodopa (LVD), carbidopa (CBD) and methyldopa (MTD) in human plasma samples. Prior to the analysis of the analytes by ATLD algorithm, three time regions of chromatograms were selected purposely for each analyte to avoid serious collinearity. Although the spectra of these analytes were similar and interferents coeluted with the analytes studied in biological samples, good recoveries of the analytes could be obtained with HPLC-DAD coupled with second-order calibration based on ATLD algorithm, additional benefits are decreasing times of analysis and less solvent consumption. The average recoveries achieved from ATLD with the factor number of 3 (N = 3) were 100.1 ± 2.1, 96.8 ± 1.7 and 104.2 ± 2.6% for LVD, CBD and MTD, respectively. In addition, elliptical joint confidence region (EJCR) tests as well as figures of merit (FOM) were employed to evaluate the accuracy of the method.     

Optimization of a high-performance liquid chromatography method for the analysis of complex polyphenol mixtures and application for sainfoin extracts (Onobrychis viciifolia)

A pentafluorophenylpropyl (PFP) stationary phase was tested for the simultaneous determination of several classes of phenolic compounds. The chromatographic results were compared with those obtained by using a bifunctional phase constituted of octadecyl and phenylpropyl bonded silica and three conventional C18 columns. The elution gradient was optimized with 5% formic acid and sodium acetate in combination with acetic acid as additives and methanol as solvents. For these evaluations, a complex phenolic extract of Onobrychis viciifolia (sainfoin) and test mixtures containing 54 standard substances including 2 simple phenolic compounds, 1 amino acid, 4 hydroxybenzoic acids (HBA), 6 hydroxycinnamic acids (HCA), 3 flavan-3-ols, 9 anthocyanins, 2 dihydroflavonols, 1 chalcone, 4 flavones, 1 isoflavone and 21 flavonols have been assayed. The perfluorinated column showed good resolution for the studied phenolic compounds which have the following elution order: HBA, HCA, flavan-3-ols, anthocyanins, dihydroflavonols, flavones, flavonols and isoflavones. Compared with other columns, it provides longer elution ranges for HBA, HCA and flavan-3-ols and increased retention times for all compound classes except anthocyanins which were similarly retained on a C18 column. Its selectivity is different from C18 and bifunctional phases. A high-performance liquid chromatography (HPLC) method with diode array detection (DAD) and post-column derivatization with p-dimethyl-aminocinnamic aldehyde (DMACA) has been validated for the analysis of individual phenolic compounds from a sainfoin plant extract (O. viciifolia).     

Evaluation of antioxidant activities of the edible and medicinal Acacia albida organs related to phenolic compounds

This study compared phenolic contents and antioxidant activity in different organs of Acacia albida (leaves and bark) and focuses on identification of phenolic compounds of leaves by HPLC-DAD. The analysed organs exhibited differences in total polyphenol contents (100 and 59.5 mg GAE g^? 1 DW). Phenolic contents of leaves were two times higher than those in bark. Ethanolic extracts exhibited good antioxidant activities with IC₅₀ = 26 μg mL^? 1 for DPPH and EC₅₀ = 50 μg mL^? 1 for FRAP. Identification by HPLC-DAD revealed the presence of nine phenolic compounds known for their high antioxidant activity. The results suggested that this species can be used as source of natural antioxidants.     

龙加通络胶囊多成分的定性及定量研究

采用高效液相色谱-串联质谱技术(HPLC-MS/MS)对龙加通络胶囊多种成分进行定性分析,并建立了其中6种主要药效成分的高效液相色谱-二极管阵列检测/蒸发光散射检测联用(HPLC-DAD/ELSD)定量分析方法。定性分析方法采用Kromasil C18(250 mm×4.6 mm,5μm)色谱柱进行分离,以乙腈-0.1%甲酸溶液为流动相进行梯度洗脱。定性分析结果根据质谱信息对其中18种化合物进行了成分归属,其中7种为文献未报道的化合物。定量分析方法采用相同的色谱柱和流动相在不同的梯度程序下进行梯度洗脱。DAD采用双波长同时检测:紫丁香苷(254 nm)、异嗪皮啶(350 nm)和绿原酸(350 nm);ELSD检测薯蓣皂苷、原薯蓣皂苷和伪原薯蓣皂苷3种甾体皂苷成分,检测条件为漂移管温度:100℃,气体流速:1.8 L/min,雾化器温度:40℃。定量分析结果显示,6种成分在各自的检测范围内线性关系良好,相关系数(r)为0.999 6~0.999 9;6种成分的平均加标回收率为99.9%~100.6%,相对标准偏差(RSD)为0.90%~1.4%。精密度、重复性以及24 h稳定性考察中,6种成分的RSD均小于2%。该方法准确可靠、重复性好,可用于龙加通络胶囊多成分的质量控制。