Evaluation of isoflavone aglycon and glycoside distribution in soy plants and soybeans by fast column high-performance liquid chromatography coupled with a diode-array detector

An ultrafast HPLC/UV-vis DAD method working at 254 nm was applied for the determination of isoflavone aglycons and glycosides (genistin, genistein, daidzein, daidzin, glycitin, glycitein, ononin, formononetin, sissotrin, and biochanin A) in roots, stems, leaves, and soy pods of soy plants and in soybeans of five varieties (Korada, Quito, Rita, OAC Erin, and OAC Vison). An Atlantis dC18 ultrafast RP chromatographic column (20 mm x 2.1 mm, 3 microm particle size) was applied for separation of the isoflavone aglycons and glycosides. A flow rate of the mobile phase (0.1% (v/v) acetic acid, pH 3.75-solvent A and methanol-solvent B) was 0.35 mL min(-1), and the column temperature was 36 degrees C. A linear gradient profile from 13 up to 22% B (v/v) from zero to 2.5 min, up to 30% B to 3.21 min, up to 35% B to 4 min, up to 40% B to 4.5 min, up to 50% B to 5.14 min, and followed by negative gradient up to 13% B to 7.71 min was used. The absolute limits of detection per sample injection (5 microL) were the highest for biochanin A (166.2 fmol) and the lowest for genistin (17.0 fmol), respectively. An accelerated solvent extraction (ASE) in combination with sonication was applied for isolation of biologically active compounds. A solid-phase extraction procedure was used to purify the extracts in the case of analysis of soy plants parts. The recoveries of 96-106% were obtained for the different concentrations of the isoflavone aglycons and glycosides and the different matrixes (overall RSDs 2-9%). The highest isoflavone concentrations were found in roots (12.5 microg g(-1) dry weight), while the amounts were about 3-1100 microg g(-1) fresh weight in different varieties of soybeans.     

Simultaneous determination of ethidimuron, methabenzthiazuron, and their two major degradation products in soil

An analytical method has been developed for the quantification of two herbicides (ethidimuron and methabenzthiazuron) and their two main soil derivatives. This method involves fluidized-bed extraction (FBE) prior to cleanup and analysis by reverse-phase liquid chromatography with UV detection at 282 nm. FBE conditions were established to provide efficient extraction without degradation of the four analytes. (14)C-labeled compounds were used for the optimization of extraction and purification steps and for the determination of related efficiencies. Extraction was optimal using a fexIKA extractor operating at 110 degrees C for three cycles (total time = 95 min) with 75 g of soil and 150 mL of a 60:40 v/v acetone/water mixture. Extracts were further purified on a 500 mg silica SPE cartridge. Separation was performed on a C18 Purosphere column (250 mm x 4 mm i.d.), at 0.8 mL min(-1) and 30 degrees C with an elution gradient made up of phosphoric acid aqueous solution (pH 2.2) and acetonitrile. Calibration curves were found to be linear in the 0.5-50 mg L(-1) concentration range. Besides freshly spiked soil samples, method validation included the analysis of samples with aged residues. Recovery values, determined from spiked samples, were close to 100%. Limits of detection ranged between 2 and 3 microg kg(-1) of dry soil and limits of quantification between 8 and 10 microg kg(-1) of dry soil. An attempt to improve these performances by using fluorescence detection following postcolumn derivatization by orthophthalaldehyde-mercaptoethanol reagent was unsuccessful.     

Isolation and identification of steroidal saponins in Taiwanese yam cultivar (Dioscorea pseudojaponica Yamamoto)

A new furostanol pentaoligoside and spirostanol tetraoligoside were isolated for the first time from yam tubers (Dioscorea pseudojaponica Yamamoto) from Taiwan, together with four known yam saponins, methyl protodioscin, methyl protogracillin, dioscin, and gracillin. Their structures were characterized as 26-O-beta-D-glucopyranosyl-22alpha-methoxyl-(25R)-furost-5-en-3beta,26-diol, 3-O-alpha-L-rhamnopyranosyl-(1-->2)-O-([alpha-L-rhamnopyranosyl-(1-->4)]-O-[alpha-L-rhamnopyranosyl-(1-->4)])-beta-D-glucopyranoside, and (25R)-spirost-5-en-3beta-ol 3-O-alpha-L-rhamnopyranosyl-(1-->2)-O-([alpha-L-rhamnopyranosyl-(1-->4)]-O-[alpha-L-rhamnopyranosyl-(1-->4)])-beta-D-glucopyranoside. The structural identification was performed using LC-MS and 1H and 13C NMR. The methanol extract of yam tubers was fractionated by XAD-2 column chromatography using a methanol/water gradient elution system to yield furostanol and spirostanol glycoside fractions. Preparative high-performance liquid chromatography, employing a C18 column and a mobile phase of methanol/water (69:31, v/v), was used to separate each furostanol glycoside, whereas a mobile phase of methanol/water (79:21, v/v) was used to resolve the individual spirostanol glycosides. The conversions from steroid saponins to diosgenin after acid hydrolysis were around 68 and 90% for furostanol and spirostanol glycosides, respectively.     

Effects of domestic processing on steroidal saponins in Taiwanese yam cultivar (Dioscorea pseudojaponica Yamamoto)

The effects of domestic processing on steroidal saponins and furostanol and spirostanol glycosides in Taiwanese yam cultivar (Dioscorea pseudojaponica Yamamoto) were studied. The baking or frying of yam slices was conducted at 150, 180, and 200 degrees C for 3, 5, and 10 min. Yam slices were steamed or microwave cooked at 2450 MHz with an output power of 850 W for 3, 5, and 10 min. The various saponins were quantified by HPLC with an evaporative light scattering detector (ELSD). Results showed that the contents of saponins were decreased along with increasing cooking temperature and time except for the steaming treatment. None of the steamed yam slices significantly change their initial compositions or quantities of furostanol and spirostanol glycosides. Fried yam slices had the highest loss of saponins, especially at 200 degrees C for 10 min (93 and 97% reductions for total furostanol and spirostanol glycosides, respectively). After baking for 10 min at 200 degrees C, the total furostanol and spirostanol glycosides were reduced by 67 and 74%, respectively. There were 12, 44, and 84% decreases for total furostanol glycosides and 10, 35, and 75% reductions for total spirostanol glycosides in yam slices after microwave cooking for 3, 5, and 10 min, respectively. Diosgenin, the aglycone of these saponins, could be found in yams after microwave cooking and baking, but not in steamed and fried yams.     

Simultaneous determination of ochratoxin A and cyclopiazonic,mycophenolic, and tenuazonic acids in cornflakes by solid-phase microextraction coupled to high-performance liquid chromatography

A solid-phase microextraction (SPME) method, coupled to liquid chromatography with diode array UV detection (LC-UV/DAD), for the simultaneous determination of cyclopiazonic acid, mycophenolic acid, tenuazonic acid, and ochratoxin A is described. Chromatographic separation was achieved on a propylamino-bonded silica gel stationary phase using acetonitrile/methanol/ammonium acetate buffer mixture (78:2:20, v/v/v) as mobile phase. SPME adsorption and desorption conditions were optimized using a silica fiber coated with a 60 microm thick polydimethylsiloxane/divinylbenzene film. Estimated limits of detection and limits of quantitation ranged from 3 to 12 ng/mL and from 7 to 29 ng/mL, respectively. The method has been applied to cornflake samples. Samples were subjected to a preliminary short sonication in MeOH/2% KHCO(3) (70:30, v/v); the mixture was evaporated to near dryness and reconstituted in 1.5 mL of 5 mM phosphate buffer (pH 3) for SPME followed by LC-UV/DAD. The overall procedure had recoveries (evaluated on samples spiked at 200 ng/g level) ranging from 74 +/- 4 to 103 +/- 9%. Samples naturally contaminated with cyclopiazonic and tenuazonic acids were found; estimated concentrations were 72 +/- 9 and 25 +/- 6 ng/g, respectively.     

Rapid extraction and high-performance liquid chromatographic determination of parthenolide in feverfew (Tanacetum parthenium).

A rapid and sensitive method for quantifying parthenolide in feverfew herb (Tanacetum parthenium) was developed that is significantly faster than those reported in the literature. The extraction system consisted of acetonitrile/water (90:10, v/v) in a bottle with stirring for 30 min. Both Soxhlet and bottle-stirring extractions were studied. Samples were analyzed using high-performance liquid chromatography with a Cosmosil C18-AR column (150 x 4.6 mm, 5 microm, 120 A). The mobile phase consisted of acetonitrile/water (55:45, v/v) with a flow rate of 1.5 mL/min and UV detection at 210 nm. Analysis time was 6 min, with a detection limit of 0.10 ng on column. The calibration curve was linear over a range of 0.160-850 microg/mL parthenolide with R(2) = 0.9999. Replicate tests indicated good reproducibility of the method with an RSD% = 0.88 (n = 10). Spike recovery of parthenolide was found to be 99.3% with an RSD% = 1.6 (n = 6).     

Triterpene saponins from barrel medic (Medicago truncatula) aerial parts

Triterpene saponins from Medicago truncatula aerial parts have been separated and their structures determined by the extensive use of 1D- and 2D-NMR experiments including 1H-1H (DQF-COSY, 1D-TOCSY) and 1H-13C (HSQC, HMBC) spectroscopy along with ESIMS. Fifteen individual compounds were isolated that included seven medicagenic acid and eight zanhic acid glycosides. Additionally, two soyasapogenol B and soyasapogenol E glycosides were identified by MS/MS and TLC. Four medicagenic acid glycosides (5, 11, 12, 14) and eight zanhic acid glycosides (1-4, 6-9) are reported here for the first time. The common feature of M. truncatula aerial part saponins is the (1-->3) linkage between the two glucose units at C-3 of medicagenic and zanhic acids, which is different from that found in alfalfa (Medicago sativa), where this linkage was always (1-->2). This may suggest differences in glucosyltransferases between these two Medicago species.     

Evaluation of the efficiency of three different solvent systems to extract triterpene saponins from roots of Panax quinquefolius using high-performance liquid chromatography

Despite the wide availability of liquid herbal extracts using mixtures of alcohol, glycerin, and water, or glycerin and water as solvents, no data on the chemical composition of such extracts is readily available. In this study, the amount and the stability of the major saponins in Panax quinquefolius root extracts, made either with 50% (v/v) aqueous ethanol, a mixture (v/v/v) of 20% ethanol, 40% glycerin, and 40% water, or with 65% (v/v) aqueous glycerin, were evaluated by HPLC-UV analysis. The amount of total saponins was highest in the 50% aqueous ethanol extract (61.7 +/- 0.1 mg/g dry root), although similar to the ethanol-glycerin-water extract (59.4 +/- 0.5 mg/g dry root). Saponins were significantly lower in the 65% aqueous glycerin extract (51.5 +/- 0.2 mg/g dry root). Interestingly, the amounts of individual saponins were quite variable depending on the solvent. This is in part due to enzymatic cleavage of ginsenosides in the glycerin containing extracts during the maceration process. Storage of the extracts at 25 degrees C over the period of a year led to a 13-15% loss of saponins with all three types of extractions.     

Ultrasensitive determination of jasmonic acid in plant tissues using high-performance liquid chromatography with fluorescence detection

An ultrasensitive and selective high-performance liquid chromatographic method for the volatile signaling hormone, jasmonic acid, has been developed based on precolumn derivatization with 1,3,5,7-tetramethyl-8-aminozide-difluoroboradiaza-s-indacene (BODIPY-aminozide). The derivatization reaction was carried out at 60 °C for 30 min in the presence of phosphoric acid. The formed jasmonic acid derivative was eluted using a mobile phase of methanol/pH 6.50 ammonium formate buffer/tetrahydrofuran (67:30:3, v/v/v) in 10 min on a C(18) column and detected with fluorescence detection at excitation and emission wavelengths of 495 and 505 nm, respectively. The detection limit (signal-to-noise ratio = 4) reached 1.14 × 10(-10) M or 2.29 fmol per injection (20 μL), which is the lowest of the existing methods. The proposed method has been successfully applied to the direct determination of trace jasmonic acid in the crude extracts of soybean leaves from soybean mosaic virus-infected and normal plants with recoveries of 95-104%.     

Investigation of sample treatment steps for the analysis of polycyclic aromatic hydrocarbons in ground coffee

Sample treatment procedures were tested for the determination of polycyclic aromatic hydrocarbons (PAHs) in ground coffee. Pressurized liquid extraction (PLE), under different conditions, was combined with several cleanup methods, namely in situ purification, C18-silica solid-phase extraction (SPE), silica SPE, acid digestion, and alkaline saponification. Soxhlet extraction and direct alkaline saponification were also tested. Best results were obtained using PLE with hexane/acetone 50:50 (v/v) under 150 degrees C. Alkaline saponification followed by cyclohexane extraction and silica SPE was required to eliminate interferent compounds. Finally, 11 PAHs could be quantified in ground coffee with limits of detection in the range of 0.11-0.18 microg kg(-1). Application to ground Arabica coffee lots from Colombia revealed the presence of several PAHs, giving an overall toxicity equivalence in the range of 0.16-0.87 microg kg(-1). PAH identification was performed using both high-performance liquid chromatography-diode array detection and gas chromatography coupled to mass spectrometry.     

Murta leaves (Ugni molinae Turcz) as a source of antioxidant polyphenols

Extracts from Murta leaves are used by Chilean natives for their benefits on health and cosmetic properties, which are mainly due to the presence of polyphenolic compounds. Extraction of such compounds is strongly influenced by several variables, the effects of which are studied in this work; the antioxidant power of the resulting extracts was measured by two different methods [2,2-diphenyl-1-picrylhydrazyl (DPPH) and thiobarbituric acid reactive substances (TBARS)]. On the whole, maximum values of polyphenolic yields and antiradical power (DPPH method) were attained at 50 degrees C (from 25 to 50 degrees C) and a solvent-to-solid ratio (v/w) of 15:1 (15:1-25:1). The solvents assayed were ethanol, methanol, and water. The highest polyphenolic yield values (2.6% expressed as gallic acid) were reached with methanol, whereas maximum EC50 was attained by the ethanol extract (0.121 mol gallic acid/mol DPPH). Contact time was shown to have only a slight influence in alcoholic extraction, while in water a remarkable effect of increasing contact times (30-90 min) was observed. Just water was the solvent that offered the best result when the antioxidant power was measured by the TBARS method. High-performance liquid chromatography-mass spectrometry analysis revealed the presence of polyphenols, basically flavonols and flavanols, sometimes glycosilated; myricetin and quercetin glycosides were detected in all extracts, whereas epicatechin was present in alcoholic extracts and gallic acid was only present in water.     

Supercritical fluid extraction of bioavailable amino acids from soils and their liquid chromatographic determination with fluorometric detection

A new procedure with supercritical CO2 modified with 0.5 mL of water and 0.75 mL of 0.1 M HCl in situ and 0.75 mL of water on-line at 15 MPa and 50 degrees C for 45 min was applied for the extraction of bioavailable amino acids from soil samples. Total extraction time was 60 min, but more favorable conditions are even possible for selected groups of amino acids. All analytes were trapped into 20 mL of methanol with satisfactory recovery (94-104%) and determined using high-performance liquid chromatography with fluorometric detection on a Zorbax Eclipse column (4.6 x 75 mm, 3.5 microm) with Na2HPO4 and acetonitrile/methanol/water as a mobile phase. Linear calibration curves were obtained (r > 0.999 except 0.99823 for Ile) with lower limits of detection (S/N = 3) in the range from 1.54 pg (Gly) to 13.5 pg (Cy2) or from 18.6 fmol (Ser) to 64.8 fmol (Lys). Validation and repeatability data are also given. Comparable results were obtained with a robust, commonly used extraction method (0.5 M ammonium acetate, 60 min in shaker, followed by filtration and lyophilization). Limiting values of artificial release of amino acids were also determined for each soil sample to eliminate any false results to ensure that all extracted amino acids originate from soil solution and exchangeable bound positions of soil samples.     

Determination of vitamin B(6) in cooked sausages

A reverse-phase high-performance liquid chromatography (HPLC) method has been described for the determination of various active forms of vitamin B(6) in meat products. Different extracting agents were tested to solubilize fully the analyte for quantification. The best data were obtained by extracting the samples with 5% (w/v) metaphosphoric acid. Separation by HPLC was performed with fluorescence detection (excitation, 290 nm; emission, 395 nm), on a 10 cm x 0.46 cm i.d. Hypersil BDS C(18) 5 microm column using a mixture of 50 mM phosphate buffer (pH 3.2) and acetonitrile (99:1, v/v) as mobile phase. Precision of the method was 0.5% (within a day) and 4.3% (between days). The detection limits were 0.020 mg/100 g for pyridoxal and pyridoxamine, 0.017 mg/100 g for pyridoxamine phosphate, 0.500 mg/100 g for pyridoxal phosphate, and 0.033 mg/100 g for pyridoxol, with a signal-to-noise ratio of 3. The recovery ranged from 92.0 to 100.0%.     

New dammarane-type saponins from the galls of Sapindus mukorossi

Five new dammarane-type saponins, 3beta,7beta,20(S),22-tetrahydroxydammar-24-ene-3-O-alpha-l-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside, 3beta,7beta,20(S),22,23-pentahydroxydammar-24-ene-3-O-alpha-l-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside, 3beta,7beta,20(S),22,25-pentahydroxydammar-23-ene-3-O-alpha-l-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside, 25-methoxy-3beta,7beta,20(S),22-tetrahydroxydammar-23-ene-3-O-alpha-l-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside, and 25-methoxy-3beta,7beta,20(R)-trihydroxydammar-23-ene-3-O-alpha-l-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside, named sapinmusaponins A (1), B (2), C (3), D (4), and E (5), respectively, together with three known phenylpropanoid glycosides (6-8), were isolated from the galls of Sapindus mukorossi. The structures of these saponins were elucidated on the basis of spectroscopic analyses and chemical methods. Preliminary bioassay data revealed that saponins 1 and 3-5 showed moderate cytotoxic activity (ED50 approximately 9-18 microg/mL) against human tumor cell lines (Hepa59T/VGH, NCI, HeLa, and Med) and that 1-5 were inactive in vitro against HIV replication in H9 lymphocytes.     

Development of a method for the simultaneous determination of six sulfonylurea herbicides in wheat, rice, and corn by liquid chromatography-tandem mass spectrometry

A sensitive and reliable method was developed and validated for trace determination of sulfonylurea herbicides residues in cereals (wheat, rice, and corn) by liquid chromatography-tandem mass spectrometry. The selected analytes were ethoxysulfuron, ethametsulfuron-methyl, bensulfuron-methyl, chlorimuron-ethyl, pyrazosulfuron-ethyl, and cyclosulfamuron. In this work, the extraction procedure was performed by using a mixture solvent of phosphate buffer (pH 9.5)/acetonitrile (8:2, v/v) as the extraction solvent and then was cleaned up by using Spe-ed C18/18% SPE cartridges, providing good recoveries for all of the tested analytes and with no matrix effects affecting method accuracy. The limits of detection for the studied analytes in cereal samples were between 0.043 and 0.23 μg kg(-1), and the limits of quantification were between 0.14 and 0.77 μg kg(-1), lower in all cases than the maximum residue limits permitted by the European Union for this kind of food. The developed methodology has demonstrated its suitability for the monitoring of these residues in cereal samples with high sensitivity, precision, and satisfactory recoveries.     

Analysis of lidocaine and its major metabolite, monoethylglycinexylidide, in elk velvet antler by liquid chromatography with UV detection and confirmation by electrospray ionization tandem mass spectrometry

A sensitive liquid chromatographic (LC) method with UV detection was developed for the determination of residues of lidocaine (LID) and its major metabolite, monoethylglycinexylidide (MEGX), in elk velvet antler. The drugs were extracted from alkaline velvet antler homogenates, cleaned up on a C(18) solid-phase extraction cartridge, and separated on an Inertsil ODS-3 (3.0 x 250 mm, 5 microm) column using an isocratic mobile phase made up of 0.05 M phosphate buffer (pH 4.0)/acetonitrile (88:12, v/v) at a flow rate of 1.0 mL/min. The limits of quantification for LID and its major metabolite, MEGX, were 10 and 20 ng/g, respectively. The method was validated and used to measure the concentration of residues of LID and MEGX in elk velvet antlers harvested after either LID anesthesia or application of a drug-free control method (electro-anesthesia, EA). No LID or MEGX residues were detected in any of the antlers harvested after EA application. No MEGX residues were detected in any of the velvet antlers harvested after LID application, but residues of LID ranging in concentration from 68 to 4300 ng/g were detected in the three sections of the velvet antlers harvested after LID administration. LC-tandem mass spectrometry was used to confirm the presence of lidocaine detected in the velvet antlers.     

Analysis of Quercetin and Kaempferol in an Alcoholic Extract of Convolvulus pilosellifolius using HPLC

A simple, rapid, and sensitive high-performance liquid chromatography (HPLC) method was developed and validated for identification and determination of flavonoids in Convolvulus pilosellifolius. The chromatographic separation was achieved in less than 6 min using C18 column (150 × 4.6 mm, 3 μm) with isocratic mixture of methanol and water containing 0.1 percent v/v formic acid in the ration of 80:20 at 258 nm with a flow rate of 0.4 mL/min. The method was validated in the linear calibration curve ranged between 1 and 300 μg/mL with detection limits of 0.39 and 0.26 μg/mL and quantification limits of 1.20 and 0.79 μg/mL for quercetin and kaempferol, respectively. Good repeatability of the method were achieved at percent relative standard deviation (RSD < 2.18 percent) with respect to inter- and intraday repeatability. Recovery values were found to be in the range of 98.2–100.2 percent, indicating high accuracy of the method. The maximum flavonoid contents were 1.07 and 1.54 percent for quercetin and kaempferol, respectively.     

甜叶菊中莱苞迪苷D、莱苞迪苷A含量测定方法的优化及应用

为比较不同品系甜叶菊中甜味品质较好的莱苞迪苷D(RD)、莱苞迪苷A(RA)含量组成,在传统C18、HSS T3、Amide色谱柱中选择适宜固定相建立高效液相色谱(HPLC)方法进行测定与分析。结果表明,HSS T3柱对甜菊糖苷选择性较好,可同时分离RA、甜菜苷(ST)、莱苞迪苷F(RF)、莱苞迪苷C(RC)、甜茶苷(RBS)、莱苞迪苷B(RB)、甜菊双糖苷(SB),其HPLC分析参数为:流动相32%乙腈和68%磷酸水(0.01%),等度洗脱,柱温40℃,波长210 nm,进样量10 μL,流速1.0 mL·min^-1;Amide柱对RD分离能力最佳,其HPLC分析参数为:流动相76%乙腈和24%水,等度洗脱,柱温40℃,波长210 nm,进样量10 μL,流速0.8 mL·min^-1。 分析比较12个扦插培育的甜叶菊品系,以编号2甜叶菊中RD含量及其占比最高,提示以其为原材料可生产含RD较高的甜菊糖苷;编号3、5、7、11甜叶菊中具较有高含量的甜菊糖苷(主要为RA),提示这些品种富含RA且甜菊糖苷产量较高;编号1、8甜叶菊中RA+RD占比较高,提示以其为原材料的甜菊糖苷甜味品质较好。本研究所建立的HPLC法为甜叶菊中RD、RA分析研究提供了方法参考,含量分析结果可为实际应用中选择适宜甜叶菊品种提供依据。     

Determination of saponins in aerial parts of barrel medic (Medicago truncatula) by liquid chromatography-electrospray ionization/mass spectrometry

Triterpene saponins from aerial parts of Medicago truncatula cv. Jemalong A-17, M. truncatula Gaertn.var. longispina Urb., and M. truncatula Gaertn. var. truncatula were profiled and quantified using reverse-phase liquid chromatography with on-line photodiode array detection and electrospray ionization mass spectrometry (LC-PDA/ESI/MS/MS). The determination was based on standard curves obtained for the 18 available saponin standards, previously isolated from Jemalong A-17. Aerial parts of all three subspecies contained 17 saponins previously identified and also a substantial amount of astragaloside VIII (3-GlcA-Xyl-Rha soyasapogenol B), not previously reported in M. truncatula. The compositions of saponin mixtures were very similar in the three subspecies with three dominant groups, recognized as zanhic acid, medicagenic acid, and soyasapogenol glycosides. Relative proportions of these three groups were also similar in the three subspecies: var. longispina had 49.5, 48.1, and 2.4%; var. truncatula, 41.5, 53.4, and 5.1%; and Jemalong A-17, 42.1, 56.6, and 1.3% of zanhic acid, medicagenic acid, and soyasapogenol glycosides, respectively. Jemalong A-17 had 30% lower total content of saponins as compared to M. truncatula var. longispina and M. truncatula var. truncatula; in relation to the dry matter, var. longispina contained 0.22%, var. truncatula, 0.22%, and Jemalong A-17, 0.15% dry matter of saponins. If one takes into consideration that this determination was performed on spring-collected samples, it can be concluded that the concentration of saponins in M. truncatula is similar to the concentration in alfalfa (Medicago sativa); the proportions of the three groups of saponins in these species are slightly different from those found in alfalfa, having a higher content of zanhic acid glycosides.     

Determination of phenolic compounds and ascorbic acid in different fractions of tomato by capillary electrophoresis with electrochemical detection

Tomato (Lycopersicon esculentum Mill.), one of the most important crops worldwide, contains different classes of substances with antioxidant properties such as carotenoids, vitamin C, and phenolics. A method based on capillary electrophoresis with electrochemical detection has been developed to analyze ascorbic acid and phenolics in the peel, pulp, and seeds of tomatoes. Operating in a wall-jet configuration, a 300 microm diameter carbon disk electrode was used as the working electrode, which exhibits a good response at +0.90 V (vs saturated calomel electrode) for the analytes. Under optimum conditions, the analytes were baseline separated within 20 min in a 50 mmol/L borate buffer (pH 8.7). Notably, excellent linearity was obtained over 3 orders of magnitude with detection limits (S/N=3) ranging from 1x10(-8) to 2x10(-7) g/mL for all analytes. This proposed method has been successfully applied to monitor the content of ascorbic acid and phenolics in real samples, and the assay results were satisfactory.