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In this study, flavonoids were extracted using accelerated solvent extraction (ASE) with 80% aqueous methanol. A high-performance liquid chromatography equipped with photodiode array detection and coupled with an electrospray ionization tandem mass spectrometry (HPLC–PDA–ESI/MSn) method has been developed for rapid identification and quantification of flavonoids in the plant extract of Rheum palmatum L. (RPL) seeds from Qinghai. Ten flavonoids from methanolic extract of RPL seeds were screened, of which epicatechin, myricetin, hyperoside, quercitrin and quercetin were identified and quantitatively analyzed for the first time. The absorbance was monitored at 280 nm for epicatechin and 360 nm for other four flavonoids. It was found that the calibration curves for all five analytes showed a good linearity (r2 > 0.999) within the test range and the data of the limit of detection (LOD) and limit of quantification (LOQ) for all investigated compounds were less than 2.98 μg mL−1 based on PDA. The relative standard deviation (R.S.D) values of the intra- and inter-day precisions were 0.98% and 1.65%, respectively. The range of mean recoveries of the five components was 91.3–93.9%, and the R.S.D was 1.3–2.9%. It was also found that the content of quercitrin is the highest in RPL seeds while the contents of epicatechin and myricetin are relatively lower. In addition, the validation procedure confirmed that this method was suitable for providing quality control evaluation of RPL seeds to ensure the therapeutic benefits. Keywords: Seeds of Rheum palmatum L., Identification, Quantification, Flavonoids, Accelerated solvent extraction, HPLC–PDA–ESI/MSn

Inula racemose Hook.f. ( I . racemosa ) is a traditional herbal medicine with strong anti-fungal and anti-inflammation activity while alantolactone (AL) and isoalantolactone (IAL) are the major active compounds of this plant. The aim of this paper was obtaining AL and IAL from the radix of I . racemosa by supercritical fluid extraction (SFE) which was optimized by response surface methodology (RSM). Our results showed that, the optimal conditions for maximum extraction efficiency were as follows: pressure 20 MPa, extraction temperature 50 °C, carbon dioxide (CO 2 ) flow rate of 17.0 × 10 −5 kg/s and extraction time of 40 min. Subsequently, an efficient freezing method was developed for purification of AL and IAL in the crude extract obtained from SFE. After purification by freezing, the total content of the target compounds was greatly improved by 30.7%. The results demonstrate that SFE coupled with freezing would be a powerful technique for extraction and purification of AL and IAL from the radix of I . racemosa .

Limonium aureum (Linn.) is a traditional Chinese medicine with strong antioxidant activity. To search for antioxidants in L. aureum , an optimized, on-line high performance liquid chromatography (HPLC) method with DPPH (1,1-diphenyl-2-picrylhydrazyl) for the detection of radical scavenging ability was developed. Response surface methodology (RSM) was used to determine the best combination of experimental conditions, such as DPPH concentration, DPPH velocity and the reaction tank length. The optimized method uses a DPPH concentration of 25.0 μg/mL, DPPH velocity of 0.45 mL/min and a 15.0 m long reaction tank. The highly sensitive, optimized method can not only be used for the detection of antioxidants in plants, but can also be coupled with mass spectrometry (MS) to obtain the mass-to-charge ratios of chemical species corresponding to the different peaks in the HPLC profiles. Seven antioxidants were identified in L. aureum using the optimized method, including myricetin-3- O -β- d -(6”- O -galloyl)-glucopyranoside, myricetin-3- O -glucoside, myricitrin, eriodictyol-7- O -glucoside, myricetin, eriodictyol and homoeridictyol.

A modified QuEChERS method was used and an ultrahigh performance liquid chromatography (UHPLC) method was developed for the rapid determination of 18 kinds of sulfonamide residues in chicken eggs. Sample preparation and cleanup conditions were carefully evaluated, and factors such as the adsorbent type and adsorption condition were key parameters in improving the cleanup. The modified QuEChERS method removed matrix interferences, and the sensitivity of the method increased about 5% for recovery and efficiency of the method. Under the optimized UHPLC method with UV detection, all 18 sulfonamide residues were simultaneously separated and rapidly identified within 15 min. The qualitative and quantitative method limits of the 18 sulfonamide residues were 2.06 to 4.12 and 6.86 to 13.7 μg·kg−1, respectively. A close linear relationship (R2 = 0.990 to 0.999) was observed within the concentration range of 0.10 to 2.25 μg·ml−1. Recovery was satisfactory (71 to 102%) for all the sulfonamides in three stand...

Microula sikkimensis is a plant rich in γ-linolenic acid. In the present study, samples of M. sikkimensis were digested using a closed-vessel microwave, after which they were analyzed by inductively coupled plasma optical emission spectrometry. The accuracy of the method was confirmed by analysis of a certified reference material of spinach. The study involved 20 samples that were collected in Qinghai–Tibet area. The relative mean concentrations of the 17 elements were as follows: K > Ca > P > Mg > Fe > Al > Na > Ba > Sr > Mn > Zn > B > Ti > Cu > Mo > Ni > Cr. The method is stable and reliable and the results are satisfactory. It is suitable for determination of the concentrations of trace elements in M. sikkimensis. Principal components analysis was applied to study the characteristic elements in M. sikkimensis and six principal components that accounted for 92.15% of the total variance were extracted from the original data. The first two components represented 51.27% of the total variability, indicating...

Gentiana straminea is the famous Tibetan folk medicine thought to cure various diseases. Historically, the Qinghai-Tibetan region has been considered as the geo-authentic production area of "Mahua Jiao," where large quantities of the medicine are grown. However, there is still little known about the phytochemical constituent spatial variation of this species. In order to find the differences between the main phytochemical constituents of G. straminea and to provide comprehensive information for quality evaluation, four main bioactive compounds (loganic acid, swertiamarin, gentiopicroside and sweroside) were analysed in 26 populations grown in areas with elevations ranging from 2320 to 4720 m across the Qinghai-Tibetan Plateau. The results showed that the four phytochemical constitutes' concentrations varied greatly in the spatial profiling of the Qinghai-Tibetan region. Throughout the range of distribution of this species, no altitudinal, latitudinal or longitudinal trends have proven to be significant in any of the four constitutes' concentrations or their summation. Furthermore, hierarchical clustering analysis and statistical tests showed that four populations (Liu0609-18, Liu0609-15, Liu2006-13-9 and Liu0609-22) had total constitute contents that were higher than other populations. The spatial profiling of the four phytochemical constituents suggests that the geo-authentic producing area of this species exists at a few regions within the Qinghai province, which could be attributed to specific environmental or genetic factors.

A sensitive and specific reversed-phase high performance liquid chromatography (RP-HPLC) method with diode array detection (DAD) was established for the quantitative determination of the nine active components, namely, swertiamarin (SWM, 1), mangiferin (MA, 2), gentipicroside (GE, 3), sweroside (SWO, 4), isoorientin (IS, 5), swertisin (SWS, 6), swertianolin (SWN, 7), 7-O-[alpha-L-rhamnopyranosyl-1 -> 2)-beta-D-xylopyranosyl]-1,8-dihydroxy-3-methoxyxanthone (RX, 8), and bellidifolin (BE, 9) used as the external standard, in Tibetan folk medicinal species Swertia franchetiana. Based on the baseline chromatographic separation of most components from the methanolic extract of Swertia franchetiana on a reversed-phase Eclipse XDB-C8 column with water-acetonitrile-formic acid as mobile phase, the nine components were identified by comparison with standard samples and qualified by using the external standard method with DAD at 254 nm. The correlation coefficients of all the calibration curves were found to be higher than 0.9980. The relative standard deviations (RSDs) of the peak areas and retention times for the nine standards were less than 2.07% and 2.86%, respectively.

The contents of trace elements, including aluminum, barium, beryllium, calcium, cobaltium, chromium, copper, iron, potassium, lanthanum, lithium, magnesium, manganese, sodium, nickel, phosphorus, lead, sulfur, silicon, titanium, vanadium, and zinc, were determined by ICP-AES. The mean concentrations of the 22 elements were as follows: K>Ca>Mg>Fe>Al>Na>S>P>Ba>Ti>Mn>Zn>Sr>Cu>Ni=Cr>Pb>V>Li=La>Co>Be. Principal components analysis of SPSS was applied to study the characteristic elements in Salvia roborwskii. Five principal components which accounted for 89.288% of the total variance were extracted from the original data. The first factor accounted for 56.401% of the total variance, which meant that aluminum, barium, beryllium, calcium, and cobaltium were the characteristic elements in S. roborwskii. This useful new method was used to evaluate the quality of S. roborwskii, and to provide the scientific foundation for its utilization and further research.

A method of reversed-phase high performance liquid chromatography coupled with fluorescence detection was developed for the separation and determination of papaverine in seeds of Papaver somniferum L. and soup of chafing dish. The liquid chromatographic experiment was carried out under the following conditions: the detector was a fluorescence with excitation wavelength at 285 nm and emission wavelength at 355 nm. An RP-C18 column (250 mm x 4.6 mm i.d., 5 microm) was used. The mobile phase was a mixture of methanol and 0.02 mol/L ammonium acetate (70: 30, v/v). The flow rate was 0.8 mL/min. A linear range was obtained from 0.1 ng to 0.1 microg with a good correlation. The lowest detection limit was 0.02 ng. The average recovery of seeds for Papaver somniferum L. was 99.0% - 100.8%. The method is rapid, accurate, sensitive and suitable for the separation and determination of papaverine in foods.

A quantitative method to determine loganic acid and gentiopicroside in Gentiana macrophylla Pall. and Gentiana straminea Maxim. by RP-HPLC was established in this paper. The two compounds were base-isolated on the coloumn of Zorbax SB-C18 (250 mm x 4.6 mm i.d., 5 microm) which eluted with MeOH and H2O (0.04% H3PO4). The methol ratio increased from 18% to 28% in 15 min with detective wave at 254 nm and coloumn temperature at 30 degree C, flow rate at 1 ml/min. A wide range of linearity and the good linear relationships were achieved on above condition. The contents of the two compounds in different parts of the two plants were also determined and compared in this paper.

A simple and rapid method for simultaneous separation and determination of xanthones in Swertia mussotii and Swertia franchetiana by high performance liquid chromatography has been established. The analysis was performed on a Kromasil C18 column (250 mm x 4.60 mm i.d., 5 microm) (at 20 degrees C) eluted with methanol and 0.1% aqueous phosphoric acid (73: 27 in volume ratio) as mobile phase at a flow rate of 1.0 mL/min and with UV detection at 260 nm. Results showed that xanthones were separated successfully from each other and from other interfering components. There was a good linear relationship between the content of component and its peak area for each xanthone, with the correlation coefficients of 0.999 2 - 0.999 9. The convenient method can be used for quantitative analysis of xanthones.

Permafrost degradation exhibits striking and profound influences on the alpine ecosystem, and response characteristics of vegetation and soil environment to such degradation inevitably differ during the entire degraded periods. However, up to now, the related research is lacking in the Qinghai?Tibetan Plateau (QTP). For this reason, twenty ecological plots in the different types of permafrost zones were selected in the upstream regions of the Shule River Basin on the northeastern margin of the QTP. Vegetation characteristics (species diversity, community coverage and biomass etc) and topsoil environment (temperature (ST), water content (SW), mechanical composition (SMC), culturable microorganism (SCM), organic carbon (SOC) and total nitrogen (TN) contents and so on), as well as active layer thickness (ALT) were investigated in late July 2009 and 2010. A spatial?temporal shifts method (the spatial pattern that is represented by different types of permafrost shifting to the temporal series that stands for different stages of permafrost degradation) has been used to discuss response characteristics of vegetation and topsoil environment throughout the entire permafrost degradation. The results showed that (1)?ST of 0?40?cm depth and ALT gradually increased from highly stable and stable permafrost (H-SP) to unstable permafrost (UP). SW increased initially and then decreased, and SOC content and the quantities of SCM at a depth of 0?20?cm first decreased and then increased, whereas TN content and SMC showed obscure trends throughout the stages of permafrost degradation with a stability decline from H-SP to extremely unstable permafrost (EUP); (2)?further, species diversity, community coverage and biomass first increased and then decreased in the stages from H-SP to EUP; (3)?in the alpine meadow ecosystem, SOC and TN contents increased initially and then decreased, soil sandy fractions gradually increased with stages of permafrost degradation from substable (SSP) to transitional (TP), and to UP. Meanwhile, SOC/TN storages increased in the former stage, while they decreased in the latter stage. This study indicated that the response characteristics of vegetation and soil environment varied throughout the entire permafrost degradation, and SW was the dominant ecological factor that limited vegetation distribution and growth. Therefore, SSP and TP phases could provide a favourable environment for plant growth, mainly contributing to high SW.