Simultaneous Determination Of Phenolic Compounds Research Articles

Reversed phase‐high‐performance liquid chromatography simultaneous estimation of phenolic compounds in hydroalcoholic extract of Potentilla fulgens root

AbstractThe roots of Potentilla fulgengs have been utilized for a long time as an astringent and tonic for treating gum and tooth diseases, microbial contagions, inflammation, diabetes mellitus, and wounds and are rich in polyphenols and flavonoids. Authentication and constant excellence are the rudimentary limitations of herbal medicines and their complexity is a key challenge for quality control. High‐performance liquid chromatography has become an important technique for the quality control of herbal medicines because of its simplicity and uniformity. It can be applied for the identification, confirmation, and quality control of herbal medicines. So, an approach using reversed‐phase high‐performance liquid chromatography was developed and validated for the simultaneous determination of phenolic compounds in the hydroalcoholic extract (methanol:water::70:30% v/v) of Potentilla fulgens roots. The results revealed that ellagic acid was found in the highest amount (8.191 ± 0.463 mg/g) followed by rutin (5.429 ± 0.062 mg/g) and caffeic acid (3.032 ± 0.453 mg/g) among the studied phenolic compounds while quercetin was not detected. The validation parameters involved selectivity, linearity, range, limits of detection and quantitation, precision, and accuracy. All calibration curves were linear (R2 > 0.99) within the range, and good precision (relative standard deviation < 2.0%) and recovery (96.129%–117.110%) were found for all standards.

RP-HPLC Method Development for Simultaneous Determination of Phenolic Compounds in Fruit Extracts of Momordica charantia from Different Locations in Malaysia

A sensitive, reproducible, and reliable reversed-phase high performance liquid chromatography (RP-HPLC) method with diode array detection (DAD) was developed and validated. Simultaneous determinations of five compounds; gallic acid, catechin, chlorogenic acid, epigallocatechin gallate and caffeic acid in four types of Momordica charantia extracts; water, ethanol, water:ethanol (1:1) and acetone were conducted. The compounds were successfully separated by C18 column (250 mm × 4.6 mm, 5 µm) with a gradient solvent system of 3% acetic acid in water:methanol:acetonitrile at flow rate of 1.0 mL/min. UV detection was carried out at 280 nm. The standard curves of the five compounds were linear in the range of 0.0396 µg/mL–100 µg/mL. The intra-assay relative standard deviation (RSD) was less than 4.97%, while the inter-assay RSD was less than 4.92%, whereas the accuracy was between 90.96% and 108.92%, respectively. Our optimised RP-HPLC-DAD method was capable to detect flavonoids and phenolic acid contents in four types of M. charantia fruits extracts simultaneously from five locations in Malaysia. The present method is recommended to be used for chemical analyses of phenolic compounds in other Momordica species.

Evaluation of anti-HMG-CoA reductase potential and simultaneous determination of phenolic compounds in hydroalcoholic extract of Ficus cunia fruits by RP-HPLC

Evaluation of anti-HMG-CoA reductase potential and simultaneous determination of phenolic compounds in hydroalcoholic extract of Ficus cunia fruits by RP-HPLC

LC-MS Identification and Quantification of Phenolic Compounds in Solid Residues from the Essential Oil Industry.

Plant solid residues obtained from the essential oil industry represent a rich source of phenolic compounds with bioactive properties to be used in the food and pharmaceutical industries. A selective and sensitive liquid chromatography-mass spectrometry (LC-MS) method was developed for the simultaneous determination of phenolic compounds in solid residues of the Lamiaceae family plants. A total of 48 compounds can be separated within 35 min by using the Poroshell-120 EC-C18 column, and a gradient mobile phase of 0.1% formic acid and acetonitrile with flow rate of 0.5 mL/min; salicylic acid was used as internal standard. The calibration curves showed good linearity in the tested concentration range for each analyte (R2 > 0.9921), while recoveries ranged from 70.1% to 115.0% with an intra-day and inter-day precision of less than 6.63% and 15.00%, respectively. Based on the retention behavior, as well as absorption and mass spectra, 17 phenolic acids, 19 flavonoids and 2 phenolic diterpenes were identified and quantified in the solid residues obtained by distillation of six aromatic plants: oregano, rosemary, sage, satureja, lemon balm, and spearmint. The method constitutes an accurate analytical and quality control tool for the simultaneous quantitation of phenolics present in solid waste residues from the essential oil industry.

A Novel, Simple Rapid Reverse-Phase HPLC-DAD Analysis, for the Simultaneous Determination of Phenolic Compounds and Abscisic Acid Commonly Found in Foodstuff and Beverages.

A novel, simple, rapid, 7-minute HPLC-DAD method for the determination of 10 phenolic compounds and abscisic acid commonly found in teas, wines, fruit and honey was successfully developed and validated according to the International Council of Harmonization (ICH) guidelines. This reverse-phase (RP) HPLC-DAD method boasts rapid separation and excellent resolution while introducing green chemistry techniques. The Agilent 1200 series diode array detector SL coupled with a reverse-phase Advanced Materials Technology Halo C18 column (100 × 3.0mm i.d., 2.7μm) contributed to the rapid analyses. This, together with a 0.1% formic acid in water (v/v) and methanol mobile phase, a flow rate of 0.8mL/min and the utilization of a meticulous gradient elution resulted in a validated method for the determination of 10 phenolic compounds and abscisic acid commonly found in various foodstuffs. The resulting method proved to be rapid, accurate, precise and linear with sensitive detection limits from 0.025μg/mL to 0.500μg/mL and percentage recoveries of 98.07%-101.94%. Phenolic compounds have been acknowledged throughout literature for their therapeutic properties, interalia, antioxidant, anti-inflammatory and antiaging due to free radical scavenging potentials. However, resulting analysis, can be frequently complicated and long and very often discounts green chemistry techniques. The developed and validated method successfully and rapidly analyses, gallic acid, caffeic acid, trans-p-coumaric acid, rutin, myricetin, abscisic acid, trans-cinnamic acid, quercetin, luteolin, kaempferol and chrysin with excellent resolution and precision.

Determination of 18 phenolic compounds in water by gas chromatography-tandem mass spectrometry coupled with solid phase extraction

At present, the kinds and the hazards of phenolic compounds in water were unclear. Research aimed at methods for the simultaneous detection of multiple phenolic compounds is still in its nascent stages. It is necessary to establish a method for the simultaneous determination of phenolic compounds in water. An analytical method was developed for the simultaneous determination of the 18 phenolic compounds in water by gas chromatography-tandem mass spectrometry (GC-MS/MS) coupled with solid phase extraction (SPE). The phenolic compounds in water were enriched and separated on an SPE column. The optimal pretreatment method was established by optimizing the chromatographic and mass spectrometric conditions. The effects of the initial pH of the water sample, type of eluting solvent, and dosage of the washing solution were investigated. Then, the 18 phenolic compounds in the water samples were determined. The optimal pretreatment extraction conditions were determined to be as follows:final pH of water sample, 3.0; eluting solvent, ethyl acetate (10 mL); and elution rate, 1 mL/min. The phenolic compounds enriched and purified by SPE were finally determined by GC-MS/MS with an electrospray ionization (EI) source. The phenolic compounds were then quantitatively analyzed by the external standard method. The average recoveries of the 18 phenolic compounds were in the range of 51.7%-117.3% at four spiked levels, and the relative standard deviations (RSDs) were in the range of 3.1%-7.4%. The limits of detections (LODs) were 0.04-0.6 μg/L. Good linear relationships were observed for the phenolic compounds in their corresponding concentration ranges. The developed method was applied to determine the phenolic compounds in six kinds of water samples from rivers and lakes, domestic water, and process water. Fifteen of the phenolic compounds were detected, but 4-nonylphenol, 3-methyl-4-nitrophenol, and 2-methyl-4,6-dinitrophenol were not. Moreover, bisphenol A, 2,4,6-tribromophenol, and 2,4-dibromophnol had the highest contents of 49.4 μg/L. The contents and kinds of phenolic compounds in the rivers and lakes were highest. However, the contents of phenolic compounds in the domestic water were adverse compared with the rivers and lakes, in accord with National Standard GB 8537-2008. As opposed to traditional analytical methods, the present method is characterized by simple operation without derivative or the need for anhydrous sodium sulfate for water removal, as well as high sensitivity, good stability, and reliability. The establishment of this method has important theoretical and practical significance for the development of standards and for the control of residue phenolic residue levels in water.

Simultaneous determination of phenolic metabolites in Chinese citrus and grape cultivars.

BackgroundAs the major bioactive compounds in citrus and grape, it is significant to use the contents of flavonoids and phenolic acids as quality evaluation criteria to provide a better view of classifying the quality and understanding the potential health benefits of each fruit variety.MethodsA total of 15 varieties of citrus and 12 varieties of grapes were collected from Fujian, China. High-performance liquid chromatography method was used for the simultaneous determination of 17 phenolic compounds, including gallic acid, chlorogenic acid, caffeic acid, syringic acid, ρ-coumaric acid, ferulic acid, benzoic acid, salicylic acid, catechin, epicatechin, resveratrol, rutin, naringin, hesperidin, quercetin, nobiletin and tangeritin in the peels of citrus and grape cultivars. Further, the cultivars of citrus and grape were classified using principal component analysis (PCA) and hierarchical cluster analysis (HCA).ResultsA thorough separation of the 17 compounds was achieved within 100 min. The tested method exhibited good linearity (the limits of detection and limits of quantification were in the range of 0.03–1.83 µg/mL and 0.09–5.55 µg/mL, respectively), precision (the relative standard deviations of repeatability were 1.02–1.97%), and recovery (92.2–102.82%) for all the compounds, which could be used for the simultaneous determination of phenolic compounds in citrus and grape. Hesperidin (12.93–26,160.98 µg/g DW) and salicylic acid (5.35–751.02 µg/g DW) were the main flavonoids and phenolic acids in 15 citrus varieties, respectively. Besides, the hesperidin (ND to 605.48 µg/g DW) and salicylic acid (ND to 1,461.79 µg/g DW) were found as the highest flavonoid and the most abundant phenolic acid in grapes, respectively. A total of 15 citrus and 12 grape samples were classified into two main groups by PCA and HCA with strong consistency.

Graphdiyne oxides as new modifier for the simultaneous electrochemical detection of phenolic compounds

Graphdiyne (GDY) is a new two-dimensional carbon nanomaterial with rich carbon chemical bonds, large conjugation system, porous structure and excellent chemical catalytic properties. In this work, graphdiyne oxide (GDYO), the oxidized form of GDY, was first used to establish a new platform for the simultaneously detection of hydroquinone (HQ), catechol (CC), resorcinol (RC) and p-nitrophenol (p-NP). The microstructure and morphologies of the materials and the surface of the modified electrode were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The electrocatalytic properties of graphene oxide (GO), GDY and GDYO for CC, HQ, RC and p-NP were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results show that the GDYO modified glassy carbon electrode (GDYO/GCE) exhibited excellent catalytic activities towards CC, HQ, RC and p-NP. The linear ranges of HQ, CC, RC and p-NP were 1 μM–980 μM, 0.6 μM–692 μM, 1 μM–300 μM and 0.6 μM–203 μM, 203 μM–692 μM with 0.3 μM, 0.2 μM, 0.3 μM and 0.2 μM, respectively. In addition, the electrochemical sensor showed good selectivity, sensitivity and stability. The application in real samples was also evaluated, and the recoveries suggesting that it could be used as an excellent potential material for the simultaneous determination of phenolic compounds in environmental samples.

Dispersive liquid-liquid microextraction coupled with pressure-assisted electrokinetic injection for simultaneous enrichment of seven phenolic compounds in water samples followed by determination using capillary electrophoresis.

Offline dispersive liquid-liquid microextraction combined with online pressure-assisted electrokinetic injection was developed to simultaneously enrich seven phenolic compounds in water samples, followed by determination using capillary electrophoresis, namely phenol, 4-chlorophenol, pentachlorophenol, 2,4,6-trichlorophenol, 2,4-dichlorophenol, 2-chlorophenol, and 2,6-dichlorophenol. Several parameters affecting separation performance of capillary electrophoresis and the enrichment efficiency of pressure-assisted electrokinetic injection and dispersive liquid-liquid microextraction were systematically investigated. Under the optimal conditions, seven phenolic compounds were completely separated within 14min and good enrichment factors were obtained of 61, 236, 3705, 3288, 920, 86, and 1807 for phenol, 4-chlorophenol, pentachlorophenol, 2,4,6-trichlorophenol, 2,4-dichlorophenol, 2-chlorophenol, and 2,6-dichlorophenol, respectively. Good linearity was attained in the range of 0.1-200μg/L for 2,4-dichlorophenol, 0.5-200μg/L for 4-chlorophenol, pentachlorophenol, 2,4,6-trichlorophenol, 2-chlorophenol, and 2,6-dichlorophenol, as well as 1-200μg/L for phenol, with correlation coefficients (r) over 0.9905. The limits of detection and quantification ranging from 0.03-0.28 and 0.07-0.94μg/L were attained. This two step enrichment method was potentially applicable for the rapid and simultaneous determination of phenolic compounds in water samples.

Layering of a film of carboxymethyl-botryosphaeran onto carbon black as a novel sensitive electrochemical platform on glassy carbon electrodes for the improvement in the simultaneous determination of phenolic compounds

In this work, a modification of a glassy carbon electrode (GCE) is presented for the first time using the polysaccharide carboxymethyl-botryosphaeran (CMB) and nanostructured carbon black (CB). The combination of the carbohydrate biopolymer and the carbonaceous nanomaterial (CMB-CB/GCE) showed improvements in the voltammetric responses of dopamine (DOP) and paracetamol (PAR) when compared to unmodified GCE. The morphology of the proposed sensor was characterized by scanning electron microscopy. The electrochemical characterization was performed by cyclic voltammetry and electrochemical impedance spectroscopy using the redox pair [Fe(CN)6]3−/4–. Using phosphate buffer solution (pH 7.0) and differential pulse voltammetry, DOP and PAR were determined simultaneously in the concentration range 0.099–2.9, and 0.70–19 μmol L–1, with limits of detection of 0.013, and 0.11 μmol L–1, respectively. The developed method with the fabricated electrochemical sensor is simple, fast, and sensitive. The proposed sensor was successfully applied to the individual and simultaneous determination of DOP and PAR in various samples, showing the practical feasibility of the proposed sensor as a novel platform for the sensitive determination of these phenolic compounds.

Morphology–dependent electrochemical activity of Cu2O polyhedrons and construction of sensor for simultaneous determination of phenolic compounds with graphene oxide as reinforcement

A series of Cu2O crystals with well–controlled cubic (C–Cu2O), star–shaped (S–Cu2O), and octahedral (O–Cu2O) structures were prepared by facile wet chemical method to explore the morphology–dependent electrocatalytic efficiency. When tested for the sensing of 4−aminophenol (4–AP), 4−chlorophenol (4–CP), and 4−nitrophenol (4–NP), it was found that the O–Cu2O exhibited the best current signals, which were mainly because of its more exposed {111} facets and higher surface area. Further, O–Cu2O crystals were homogeneously dispersed on graphene oxide (GO) surface to achieve a hierarchical reinforcement structure. The electrode modified by O–Cu2O@GO showed high electrocatalytic activity toward the oxidation of 4–AP, 4–CP, and 4–NP, and could realize the selective detection of phenolic compounds in ternary electrolyte solutions and industrial wastewater. This work is beneficial to morphology tailoring and provides novel way to improve the electrochemical property of oxide–based catalysts as the promising applications in electrochemical sensors.

Simultaneous Determination of Phenolic Compounds in Leptadenia pyrotechnica (Forssk.) Decne. by Using High-Performance Liquid Chromatography (HPLC-DAD-UV).

During the present study, an endeavor has been made to produce a simple, rapid, and simultaneous method for determination of phenolic compounds by using high-performance liquid chromatography in aerial parts of Leptadenia pyrotechnica (Forssk.) Decne. collected from the Indian Thar Desert. The optimized process was used for the quantification of ten phenolic compounds. The chromatographic separation was accomplished on an Atlantis T3 column at 25°C with isocratic elution. A mixture of acetonitrile and water was used as the mobile phase at a flow rate of 0.8 mL/min. The linear regression examination data for the calibration plots displayed a good linear relationship with r2 > 0.999 in the concentration range of 2–20 µL. In the methanolic extracts of the whole plant of L. pyrotechnica, the content of caffeic acid (3.3%) was reported to be the highest concentration.

Development and Validation of an Analytical Methodology Based on Liquid Chromatography-Electrospray Tandem Mass Spectrometry for the Simultaneous Determination of Phenolic Compounds in Olive Leaf Extract.

A simple method was validated for the analysis of 31 phenolic compounds using liquid chromatography-electrospray tandem mass spectrometry. Proposed method was successfully applied to the determination of phenolic compounds in an olive leaf extract and 24 compounds were analyzed quantitatively. Olive biophenols were extracted from olive leaves by using microwave-assisted extraction with acceptable recovery values between 78.1 and 108.7%. Good linearities were obtained with correlation coefficients over 0.9916 from calibration curves of the phenolic compounds. The limits of quantifications were from 0.14 to 3.2 μg g-1. Intra-day and inter-day precision studies indicated that the proposed method was repeatable. As a result, it was confirmed that the proposed method was highly reliable for determination of the phenolic species in olive leaf extracts.

Poly (dopamine quinone-chromium (III) complex) microspheres as new modifier for simultaneous determination of phenolic compounds

In this study, poly(dopamine-quinone chromium (III))-microspheres (PDQCM) were used for the modification of graphite paste electrode (GPE) for simultaneous voltammetric determination of 4-Amino Phenol (AP), Phenol (Ph) and 4-Nitro Phenol (NP). The PDQCM and the GPE modified with PDQCM were characterized by field emission scanning electron microscopy, Energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy and electrochemistry methods such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The proposed modified electrode exhibits high electrocatalytic activity toward electrooxidation of AP, Ph, and NP to three well-separated peaks in the potential range from 0.2 to 1.3V using CV and DPV methods in phosphate buffer solution with pH 2.0. Under the optimum conditions, detection limits of 0.5, 0.6 and 0.8µM were obtained for AP, Ph, and NP, respectively. Moreover, GPE/PDQCM was successfully used for simultaneous determination of AP, Ph, and NP in tap and river waters.

Simultaneous determination of phenolic compounds in sesame oil using LC–MS/MS combined with magnetic carboxylated multi-walled carbon nanotubes

A novel magnetic carboxylated multi-walled carbon nanotubes (c-MWCNT-MNPs) was proposed for magnetic solid-phase extraction coupled with liquid chromatography–tandem mass spectrometry to determine phenolic compounds in sesame oil. In this study, c-MWCNT-MNPs were acquired by simply dispersing Fe3O4 magnetic nanoparticles into carboxylated multi-walled carbon nanotubes. The major parameters affecting extraction efficiency were optimized, including the type and volume of desorption solvents, extraction and desorption time, washing solution, and sorbent amount. The limit of quantifications and limit of detections were from 0.03μg/kg to 43.00μg/kg and from 0.01μg/kg to 13.60μg/kg, respectively. The recoveries of phenolic compounds in vegetable oils were in the range of 83.8–125.9% with inter-day and intra-day precisions of less than 13.2%. It was confirmed that this method was simple, rapid and reliable with an excellent potential for routine analysis of phenolic compounds in oil samples.

Electrochemical study for the simultaneous determination of phenolic compounds and emerging pollutant using an electroanalytical sensing system based on carbon nanotubes/surfactant and multivariate approach in the optimization

A voltammetric method for the simultaneous determination of phenolic compounds hydroquinone (HQ), catechol (CT), 4-nitrophenol (p-NP), and the emerging pollutant acetaminophen (AC) using a multi-walled carbon nanotubes (MWCNT) paste electrode in the presence of surfactant has been described. The relationship of oxidation potential and pH revels a Nernstian system for all compounds and the calculated diffusion coefficients were found to be 5.45×10−6, 3.35×10−5, 1.17×10−5, and 2.60×10−6cm2s−1 for HQ, CT, AC, and p-NP, respectively. The best analytical condition for the simultaneous determination of phenolic compounds has been achieved by using a multi-response optimization approach. Under the optimum condition—Britton–Robinson buffer at 0.1molL−1 pH8, CPB at 450μmolL−1, and differential pulse voltammetry (pulse amplitude of 117mV, pulse time of 23.98ms, and scan rate of 8.61mVs−1), limits of detection of 0.07, 0.49, 0.29, and 0.32μmolL−1 for HQ, CT, AC, and p-NP were obtained, respectively. The method permits the simultaneous analysis in the presence of some pesticides and other phenolic compounds. The developed method was applied in water (tap and domestic wastewater) and dermatological creams, whose accuracy has been attested through addition and recovery assays and comparing with HPLC-DAD as a reference method.

Simultaneous Determination of Phenolic Compounds in Different Matrices using Phenyl-Hexyl Stationary Phase

A novel unique liquid chromatographic method has been developed consisting of diode array and fluorescence detection, using phenyl-hexyl stationary phase of the column, for the determination of over thirty phenolic compounds (anthocyanins, flavonols, flavan-3-ols, hydroxybenzoic acids, hydroxycinammic acids, and stilbenes). The method was validated including the following parameters: linearity, limits of detection and quantification, precision, and reproducibility. Excellent selectivity and sensitivity have been achieved. Detection levels ranging from 1.79 × 10−5 mg/L to 0.26 mg/L were obtained. New fluorescence wavelengths for detection of flavan-3-ols (λex = 225 and λem = 320 nm) were more sensitive than previously published. The new optimized method showed good repeatability and reproducibility, and values for relative standard deviations (RSD) were less than 3 %. Applicability of the method was demonstrated for five different matrices, white and red wine from Vitis vinifera cultivars, apple cider, blackberry wine, and grape skin extracts, showing that method is robust and can be applied for routine analysis.

Simultaneous determination of phenolic compounds in Cynthiana grape (Vitis aestivalis) by high performance liquid chromatography–electrospray ionisation–mass spectrometry

Phenolic acids, flavanols, flavonols and stilbenes (PAFFS) were isolated from whole grapes, juice, or pomace and purified using enzymatic hydrolysis. Only anthocyanin mono-glucosides and a few of the oligomers from Cynthiana grape (Vitis aestivalis) were analysed. Flavonoid-anthocyanin mono-glucosides (FA) were isolated using methanol/0.1% hydrochloric acid extraction. In addition, crude extractions of phenolic compounds from Cynthiana grape using 50% methanol, 70% methanol, 50% acetone, 0.01% pectinase, or petroleum ether were also evaluated. Reverse phase high performance liquid chromatography (RP-HPLC) with photodiode array (PDA) detector was used to identify phenolic compounds. A method was developed for simultaneous separation, identification and quantification of both PAFFS and FA. Quantification was performed by the internal standard method using a five points regression graph of the UV–visible absorption data collected at the wavelength of maximum absorbance for each analyte. From whole grape samples nine phenolic compounds were tentatively identified and quantified. The individual phenolic compounds content varied from 3 to 875mgkg−1 dry weight. For juice, twelve phenolic compounds were identified and quantified. The content varied from 0.07 to 910mgkg−1 dry weight. For pomace, a total of fifteen phenolic compounds were tentatively identified and quantified. The content varied from 2mgkg−1 to 198mgkg−1 dry matter. Results from HPLC analysis of the samples showed that gallic acid and (+)-catechin hydrate were the major phenolic compounds in both whole grapes and pomace. Cyanidin and petunidin 3-O-glucoside were the major anthocyanin glucosides in the juice.

Fingerprint Analysis and Simultaneous Determination of Phenolic Compounds in Extracts of Curculiginis Rhizoma by HPLC-Diode Array Detector

Curculiginis Rhizoma (Curculigo orchioides GAERTN.) is a well-known Chinese herbal medicine, as well as an important Rasayana drug in India. Current criteria of quality control on this herb are to quantitatively analyze single compound curculigoside, which fail to comprehensively evaluate quality of this herb. In this paper, a simple and reliable HPLC coupled with diode array detector (DAD) method was developed to evaluate the quality of Curculiginis Rhizoma through establishing chromatographic fingerprint and simultaneously quantitating four phenolic compounds, orcinol glucoside, orcinol, 2,6-dimethoxybenzoic acid and curculigoside. The fingerprint displayed eleven common peaks, and the similarity index of different samples was in a range of 0.890-0.977. Validation of the method was acceptable, with 96.03-102.82% accuracy in recovery test and inter and intra-day precisions were less than 2%. This developed method by having a combination of chromatographic fingerprint and quantitation analysis could be applied to the quality control of Curculiginis Rhizoma.

Simultaneous determination of phenolic compounds and triterpenic acids in oregano growing wild in Greece by 31P NMR spectroscopy

(31)P nuclear magnetic resonance (NMR) spectroscopy was used to detect and quantify simultaneously a large number of phenolic compounds and the two triterpenic acids, ursolic acid and oleanolic acid, extracted from two oregano species Origanum onites and Origanum vulgare ssp. Hirtum using two different organic solvents ethanol and ethyl acetate. This analytical method is based on the derivatization of the hydroxyl and carboxyl groups of these compounds with the phosphorous reagent 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxa phospholane and the identification of the phosphitylated compounds on the basis of the (31)P chemical shifts. Unambiguous assignment of the (31)P NMR chemical shifts of the dihydroxy- and polyhydroxy-phenols in oregano species as well as those of the triterpenic acids was achieved upon comparison with the chemical shifts of model compounds assigned by using two-dimensional NMR techniques. Furthermore, the integration of the appropriate signals of the hydroxyl derivatives in the corresponding (31)P NMR spectra and the use of the phosphitylated cyclohexanol as an internal standard allowed the quantification of these compounds. The validity of this technique for quantitative measurements was thoroughly examined.