Chemical identification and quality evaluation of Lycopus lucidus Turcz by UHPLC‐Q‐TOF‐MS and HPLC‐MS/MS and hierarchical clustering analysis

Lycopus lucidus Turcz has been used as a traditional phytomedicine for menstrual disorder, amenorrhea, menstrual cramps, inflammation and cardiovascular diseases. However, there is not enough information about identification and quantification for the chemical constituents of L. lucidus Turcz. In this work, a simple, rapid and sensitive UHPLC‐Q‐TOF‐MS method was developed for characterization and identification of the phytochemical compositions in L. lucidus Turcz in negative ion mode. A total of 37 compounds, including 15 phenolic acids, 12 flavonoids, three triterpenoids and seven organic acids were tentatively characterized and identified by means of the retention time, accurate mass and characteristic fragment ions. Thirteen compounds were reported for the first time in L. lucidus Turcz. Among of them, 11 compounds were further quantified by multiple reactions monitoring. The results showed good performance with respect to linearity (r > 0.9959), repeatability (RSD < 2.6%), intra‐ and inter‐day precision (RSD < 3.2%), recovery (93.1–104.9%), and lower limit of quantification (5–50 ng/mL). Subsequently, the results were analyzed and classified by hierarchical cluster analysis. The research could be applied for identification and quality evaluation for L. lucidus Turcz.     

Development of a UHPLC–MS/MS method for the quantitation of bioactive compounds in Phyllanthus species and its herbal formulations

Phyllanthus species are extensively used in traditional medicines for the treatment of hepatic diseases due to their bioactive hypophyllanthin and phyllanthin. This work describes the development and validation of an ultra high performance liquid chromatography with tandem mass spectrometry method in polarity switching multiple reaction monitoring mode for the simultaneous detection and quantitation of 23 compounds using ultra‐performance liquid chromatography coupled with electrospray‐hybrid triple quadrupole‐linear ion trap mass spectrometer. The validated parameters showed good linearity (R ² ≥ 0.996), limit of detection (0.05–1.62 ng/mL), limit of quantitation (0.15–4.95 ng/mL), precisions (intra‐day: RSD ≤ 2.11%), (inter‐day: RSD ≤ 2.91%), stability (RSD ≤ 2.56%) and overall recovery (98.22–104.48%; RSD ≤ 2.93%). The validated method was successfully applied in ethanolic extracts of P. amarus, P. niruri , P. emblica , P. fraternus , fractions of P. amarus and their herbal formulations for quantitation. The maximum content of hypophyllanthin (29.40 mg/g) and phyllanthin (56.60 mg/g) was detected in ethyl acetate fraction of P. amarus . The total content of 23 compounds was abundant in the ethanolic extract of P. emblica fruit. Principal component analysis was used to differentiate the selected Phyllanthus species and their herbal formulations. The results indicated that the present method could be used for quality control of Phyllanthus species and its herbal formulations.     

High‐performance liquid chromatography with photodiode array detection and chemometrics method for the analysis of multiple components in the traditional Chinese medicine Shuanghuanglian oral liquid

Shuanghuanlian oral liquid, a traditional Chinese medicine preparation, is a mixture of three herbs (Flos Lonicerae, Radix Scutellariae and Fructus Forsythiae). In this study, the quantitative analysis of three main active compounds, chlorogenic acid, forsythin and baicalin in samples from different manufacturers was performed rapidly by high‐performance liquid chromatography coupled with photodiode array detection followed by Contour Projection coupled to stepwise regression treatment of the obtained three‐dimensional spectra in which the partial overlap between adjacent target components existed. The method was validated for linearity (R>0.9940), precision (RSD<1.25%), recovery (92.20–102.50%), limit of detection (0.01–0.02 μg/mL) and limit of quantification (0.03–0.07 μg/mL). The results indicated that the combination of the three‐dimensional spectra of traditional Chinese medicine and Contour Projection‐stepwise regression offered an accurate, simple, low‐cost and eco‐friendly way for the rapid quantitative analysis of Shuanghuanlian oral liquid samples.     

Chromatographic method for the simultaneous quantification of dapsone and clofazimine in nanoformulations

The low bioavailability and nonspecific distribution of dapsone and clofazimine, commonly applied in combination for the treatment of leprosy, can produce toxic effects. Nanotechnological approaches enhance the delivery of these drugs. Therefore, a high‐performance liquid chromatography method was developed for the simultaneous determination of dapsone and clofazimine loaded in nanoformulations for quality control purposes. Chromatographic separation was achieved on a reversed‐phase Kinetex core‐shell C18 column, followed by spectrophotometric detection at 280 nm. Considering the different physicochemical properties of dapsone and clofazimine, elution was performed in gradient mode using an aqueous acetate buffer (50 mmol/L, pH 4.8) and an increasing acetonitrile content from 27 to 63% v/v at a flow rate of 1.0 mL/min with retention times of 6.2 and 14.0 min, respectively. The method was validated according to the European Medicines Agency guideline and it was found to be specific, accurate (99.6–114.0%), and precise for intra‐ (RSD ≤ 1.8%) and interday assays (RSD ≤ 12.5%). Both drugs showed stability after 24 h at room temperature and over three freeze–thaw cycles with recoveries ≥86.2%. Low temperature (4°C) in the autosampler caused the precipitation of clofazimine and must be avoided. The validated method was successfully applied in the quantification of both drugs in nanoformulations.     

Simultaneous determination of seven phenolic acids in three Salvia species by capillary zone electrophoresis with β‐cyclodextrin as modifier

A capillary zone electrophoresis method was developed for the simultaneous determination of seven phenolic acids, including protocatechuic aldehyde ( 1 ), salvianolic acid C ( 2 ), rosmarinic acid ( 3 ), salvianolic acid A ( 4 ), danshensu ( 5 ), salvianolic acid B ( 6 ), and protocatechuic acid ( 7 ), in Danshen and related medicinal plants. A running buffer composed of 20 mM sodium tetraborate adjusted to pH 9.0, and containing 12 mM β‐cyclodextrin as modifier. Baseline separation was achieved within 17 min running at the voltage of 20 kV, temperature of 25°C and detection wavelength of 280 nm. The relative standard deviations of migration time ranged from 0.2 to 0.7% and the peak area ranged from 1.5 to 3.7% for the seven analytes, indicating the good repeatability of the proposed method. The method was extensively validated by evaluating the linearity (R² ≥ 0.9992), limits of detection (0.14–0.36 μg/mL), limits of quantification (0.47–1.19 μg/mL), and recovery (96.0–102.6%). Under the optimum conditions, samples of Danshen and related medicinal plants were analyzed using the developed method with high separation efficiency.     

Silica‐based magnetic hybrid nanocomposite for the extraction and preconcentration of some organophosphorus pesticides before gas chromatography

The precise control of pesticide residues in foodstuffs depends significantly on the clean extraction of analytes using specifically designed separation methods. In this study, a one‐pot sol–gel process was used for the preparation of a magnetic hybrid silica gel tetraethylortho silicate‐cyanopropyltriethoxy silane nanocomposite. The prepared material was characterized using energy dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy, single‐point specific surface area, and scanning electron microcopy. The synthesized magnetic hybrid material was used as a solid phase extraction sorbent for the extraction and preconcentration of some organophosphorus pesticides before gas chromatography with a microelectron capture detector. The performance of the proposed magnetic solid‐phase extraction technique was validated by linearity (0.05–2 ng/mL), correlation coefficients (r² = 0.9993–0.9997), limit of detection (0.02–0.06 ng/mL, S/N = 3, n = 3), and intraday (RSD = 1.5–8.7%, n = 3) and interday precision (RSD = 5.5–9.3%, n = 12), while the recovery in real samples and equilibrium adsorption capacity was 72.02–103.84% and 8–20 mg/g, respectively. The magnetic solid‐phase extraction based on the hybrid nanocomposite revealed a high enrichment factor, an appropriate dynamic range, and great absorptive ability toward the selected organophosphorus pesticides spiked in real water samples.     

Simultaneous determination of eight Danshen polyphenols in rat plasma and its application to a comparative pharmacokinetic study of DanHong injection and Danshen injection

Polyphenols derived from Danshen are responsible for the therapeutic effects of DanHong injection, a two‐herb combination of Danshen and Honghua. Whether the pharmacokinetics of Danshen polyphenols is changed by coexisting Honghua constituents remains unknown. A sensitive ultra high performance liquid chromatography with tandem mass spectrometry method was developed in this study for simultaneous determination of eight Danshen polyphenols (i.e., protocatechuic aldehyde, protocatechuic acid, tanshinol, salvianolic acid D, rosmarinic acid, salvianolic acid A, lithospermic acid, and salvianolic acid B) in rat plasma and applied to a comparative pharmacokinetic study of DanHong injection and Danshen injection. Liquid chromatography conditions, mass spectrometry parameters, and sample preparation were optimized step by step. The calibration curves showed good linearity (r > 0.99) for all the polyphenols. The mean extraction efficiencies ranged from 62.2 to 88.7% with negligible matrix effects. The intrabatch and interbatch precision at all the quality control levels were less than 15% of the nominal concentrations with accuracy of 88.8–114%, except that precision and accuracy at lower limit of quantitation were 3.2–17.3 and 95.7–119%, respectively. Comparative pharmacokinetic study suggested that the coexisting Honghua constituents might have negligible influences on the pharmacokinetics of Danshen polyphenols from DanHong injection. The bioanalytical method could also be applied to pharmacokinetic studies of other Danshen herbal products.     

New oil‐in‐salt liquid‐phase microextraction on permutite for the extraction and concentration of alkaloids in Coptis chinensis

A novel oil‐in‐salt liquid‐phase microextraction was developed and introduced for the extraction and concentration of the trace levels of active alkaloids in Coptis chinensis prior to being analyzed by high‐performance liquid chromatography with ultraviolet detection. Also, the oil‐in‐salt extraction mechanism was analyzed, the enrichment factor and extraction recovery were redefined, and the proposed method was compared with other methods. In the approach, the mixed solvent of pentanol/octanol (6:4, v/v) and NaCl (20% w/v) are immobilized on the permutite surface in turn to form oil‐in‐salt double membranes, through which the target analytes can be molecularized though salting‐out effect and be extracted by organic solvent. The main parameters affecting the approach were investigated and optimized. Under the optimized conditions, the enrichment factors of the analytes were 30–117, the linear ranges were 0.002–2 μg/mL for jatrorrhizine, coptisine, and palmatine, and 0.001–3 μg/mL for berberine (r ² ≥ 0.9923). The limits of detection were less than 1 ng/mL. Satisfactory recoveries (84.3%–120.3%) and precision (0.9%–7.5%) were also obtained. These results confirm that the approach is a simple and reliable sample pretreatment procedure and allows for the quantification of active alkaloids in C. chinensis at actual concentration levels.     

Adsorbed hollow fiber‐based biological fingerprinting for the discovery of platelet aggregation inhibitors from Danshen–Honghua decoction

For lead compound discovery from natural products, hollow fiber cell fishing with chromatographic analysis is a newly developed method. In this study, an adsorbed hollow fiber‐based biological fingerprinting method was firstly developed to discover potential platelet aggregation inhibitors from Danshen–Honghua decoction. Platelets were seeded on the fiber and their survival rate was tested. Results indicated that more than 92% platelets survived during the whole operation process. Ranitidine and tirofiban were used as positive and negative control respectively to verify the reliability of the presented approach. The main variables such as amount of extract and stirring time that affect the adsorbed hollow fiber‐based biological fingerprinting process were optimized, and the repeatability of this method was also investigated. Finally, 12 potential active compounds in Danshen–Honghua decoction were successfully detected using the established approach and structures for nine of them were tentatively identified by liquid chromatography with mass spectrometry analysis. In addition, the in vitro platelet aggregation inhibition test was carried out for five of the nine hit compounds, and three active components, namely, lithospermic acid, salvianolic acid A, and salvianolic acid B were confirmed. These results proved that the proposed method could be an effective approach for screening platelet inhibitors from plant extracts.     

Ultra‐high performance liquid chromatography with tandem mass spectrometry method for the simultaneous quantitation of five phthalides in rat plasma: Application to a comparative pharmacokinetic study of Huo Luo Xiao Ling Dan and herb‐pair extract

A fast, sensitive, and reliable ultra‐high performance liquid chromatography with tandem mass spectrometry method has been developed and validated for the simultaneous quantitation and pharmacokinetic study of five phthalides (senkyunolide A, ligustilide, butylidenephthalide, 3‐butylphthalide, and levistilide A) in rat plasma after oral administration of Huo Luo Xiao Ling Dan (HLXLD) or Angelica sinensis‐‐Ligusticum chuanxiong herb pair (DG‐CX) between normal and arthritis rats. After extraction from blood, the analytes and internal standard were subjected to ultra‐high performance liquid chromatography with a Shim‐pack XR‐ODS column (75 × 3.0 mm², 2.2 μm particles) and mobile phase was composed of methanol and water (containing 0.05% formic acid) under gradient elution conditions, with an electrospray ionization source in the positive ionization and multiple reaction monitoring mode. The lower limits of quantification were 0.192–0.800 ng/mL for all the analytes. Satisfactory linearity, precision, accuracy, mean extraction recovery, and acceptable matrix effect have been achieved. The validated method was successfully applied to a comparative pharmacokinetic study of five bioactive components in rat plasma after oral administration of HLXLD or DG‐CX alone, respectively, between normal and arthritic rats. The results showed that there were unlike characters of pharmacokinetics among different groups.     

Determination of pterostilbene in rat plasma by a simple HPLC‐UV method and its application in pre‐clinical pharmacokinetic study

A simple HPLC‐UV method was developed and validated for the quantification of pterostilbene (3,5‐dimethoxy‐4'‐hydroxy‐trans‐stilbene), a pharmacologically active phytoalexin in rat plasma. The assay was carried out by measuring the UV absorbance at 320 nm. Pterostilbene and the internal standard, 3,5,4'‐trimethoxy‐trans‐stilbene eluted at 5.7 and 9.2 min, respectively. The calibration curve (20–2000 ng/mL) was linear (R² > 0.997). The lower limits of detection and of quantification were 6.7 and 20 ng/mL, respectively. The intra‐ and inter‐day precisions in terms of RSD were all lower than 6%. The analytical recovery ranged from 95.5 ± 3.7 to 103.2 ± 0.7% while the absolute recovery ranged from 101.9 ± 1.1 to 104.9 ± 4.4%. This simple HPLC method was subsequently applied in a pharmacokinetic study carried out in Sprague–Dawley rats. The terminal elimination half‐life and clearance of pterostilbene were 96.6 ± 23.7 min and 37.0 ± 2.5 mL/min/kg, respectively, while its absolute oral bioavailability was 12.5 ± 4.7%. Pterostilbene appeared to have better pharmacokinetic characteristics than its natural occurring analog, resveratrol. Copyright © 2009 John Wiley & Sons, Ltd.     

Design,Synthesis and In Vitro Anti‐mycobacterial Activity of Propylene‐1H‐1,2,3‐triazole‐4‐methylene‐tethered Isatin‐moxifloxacin Hybrids

Ten propylene‐1H‐1,2,3‐triazole‐4‐methylene‐tethered isatin‐moxifloxacin hybrids 5a–j were synthesized via Cu‐promoted azide‐alkyne cycloaddition reaction, and screened for their in vitro anti‐mycobacterial activities against Mycobacterium tuberculosis H₃₇Rv and multidrug‐resistant tuberculosis. The results showed that all the synthesized hybrids [minimum inhibitory concentration (MIC): 0.25–4.0 μg/mL] displayed considerable activities against the tested two strains, but all less active than the parent moxifloxacin (MIC: 0.10 and 0.12 μg/mL). The resistance index of the most targets was around 1, suggesting this kind of hybrids could reduce the cross–resistance to some extent. Among them, hybrid 5 g was found most active against Mycobacterium tuberculosis H₃₇Rv with MIC of 0.39 μg/mL, which was comparable with rifampicin (MIC: 0.39 μg/mL), while conjugate 5a (MIC: 0.25 μg/mL) was 128– > 512 times more active than rifampicin (MIC: 32 μg/mL) and isoniazid (MIC: >128 μg/mL) against multidrug‐resistant tuberculosis.     

Solid acids assisted matrix solid‐phase dispersion microextraction of alkaloids by capillary electrophoresis coupled with quadrupole time‐of‐flight mass spectrometry

The quantification of three alkaloids is important because quantitative study is a means of assessing the reliability of the experimental method, and three alkaloids of peimine, peiminine, and peimisine are main active ingredients in Chinese Pharmacopoeia 2015. An effective method based on the matrix solid‐phase dispersion microextraction was developed for the extraction of alkaloid compounds in Fritillariae Thunbergii Bulbus. Target analytes were analyzed by capillary electrophoresis coupled with quadrupole time‐of‐flight mass spectrometry. The optimized experimental condition was that 50 mg Fritillariae Thunbergii Bulbus was blended homogeneously with 10 mg citric acid for 5 min. Two hundred microliters of water acidized by 1 mol/L hydrochloric acid (pH = 4.5) was selected to elute tested alkaloids. The results demonstrated that the investigated method had low limits of detection (1.32–1.59 ng/mL), good recoveries (86.63–98.12%), and reproducibility (relative standard deviations of peak areas < 0.87%). The proposed matrix solid‐phase dispersion microextraction coupled with capillary electrophoresis combined with quadrupole time‐of‐flight mass spectrometry was successfully applied for the extraction of alkaloids in plants.     

Development and validation of an ultra high performance liquid chromatography electrospray ionization tandem mass spectrometry method for the simultaneous determination of selected flavonoids in Ginkgo biloba

A rapid and sensitive ultra high performance liquid chromatography electrospray ionization tandem mass spectrometry method was developed and validated for the simultaneous determination of 13 flavonoids in leaf, stem, and fruit extracts of male and female trees of Ginkgo biloba to investigate gender‐ and age‐related variations of flavonoids content. Chromatographic separation was accomplished on an Acquity UPLC BEH C₁₈ column (50 mm × 2.1 mm id, 1.7 μm) in 5 min. Quantitation was performed using negative electrospray ionization mass spectrometry in multiple reaction monitoring mode. The calibration curves of all analytes showed a good linear relationship (r² ≥ 0.9977) over the concentration range of 1–1000 ng/mL. The precision evaluated by an intra‐ and interday study showed RSD ≤ 1.98% and good accuracy with overall recovery in the range from 97.90 to 101.09% (RSD ≤ 1.67%) for all analytes. The method sensitivity expressed as the limit of quantitation was typically 0.25–3.57 ng/mL. The results showed that the total content of 13 flavonoids was higher in the leaf extract of an old male Ginkgo tree compared to young female Ginkgo trees.     

Determination of N‐nitrosamines in cosmetic products by vortex‐assisted reversed‐phase dispersive liquid–liquid microextraction and liquid chromatography with mass spectrometry

A new analytical method for the simultaneous determination of trace levels of seven prohibited N‐nitrosamines (N‐nitrosodimethylamine, N‐nitrosoethylmethylamine, N‐nitrosopyrrolidine, N‐nitrosodiethylamine, N‐nitrosopiperidine, N‐nitrosomorpholine, and N‐nitrosodiethanolamine) in cosmetic products has been developed. The method is based on vortex‐assisted reversed‐phase dispersive liquid–liquid microextraction, which allows the extraction of highly polar compounds, followed by liquid chromatography with mass spectrometry. The variables involved in the extraction process were studied to obtain the highest enrichment factor. Under the selected conditions, 75 μL of water as extraction solvent was added to 5 mL of n‐hexane sample solution and assisted by vortex mixing during 30 s to form the cloudy solution. The method was successfully validated showing good linearity (0.5–50 ng/mL), enrichment factors up to 65 depending on the target compound, limits of detection values of 1.8–50 ng/g, and good repeatability (RSD < 9.8%). Finally, the proposed method was applied to different cosmetic samples. Quantitative relative recovery values (80–113%) were obtained, thus showing that matrix effects were negligible. The achieved analytical features of the proposed method, besides of its simplicity and affordability, make it useful to perform the quality control of cosmetic products to ensure the safety of consumers.     

Simultaneous determination of major components of Huangqi–Honghua extract in rat plasma using LC–MS/MS and application to a pharmacokinetic study

A sensitive and reliable LC–MS/MS method was developed and validated for simultaneous quantification of the major components of Huangqi–Honghua extact in rat plasma, including hydroxysafflor yellow A (HSYA), astragaloside IV (ASIV), calycosin‐7‐O‐β‐d ‐glucoside (CAG), calycosin, calycosin‐3′‐O‐glucuronide (C‐3′‐G) and calycosin‐3′‐O‐sulfate (C‐3′‐S). After extraction by protein precipitation with acetonitrile and methanol from plasma, the analytes were separated on a Hypersil BDS C₁₈ column by gradient elution with acetonitrile and 5 mM ammonium acetate. The detection was carried out on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization source switched between negative and positive modes. HSYA was monitored in negative ionization mode from 0 to 4.9 min, and ASIV, CAG, calycosin, C‐3′‐G and C‐3′‐S were determined in positive ionization mode from 4.9 to 10 min. The lower limits of quantification of the analytes were 6.25 ng/mL for HSYA, 0.781 ng/mL for CAG and 1.56 ng/mL for ASIV and calycosin. The intra‐ and inter‐assay precision (RSD) values were within 13.43%, and accuracy (RE) ranged from ?8.75 to 9.92%. The validated method was then applied to the pharmacokinetic study of HSYA, ASIV, CAG, calycosin, C‐3′‐G and C‐3′‐S in rat after an oral administration of Huangqi–Honghua extract.     

Ultra‐performance convergence chromatography method for the determination of four chromones and quality control of Saposhnikovia divaricata (Turcz.) Schischk.

Ultra‐performance convergence chromatography is an environmentally friendly analytical technique that employs dramatically reduced amounts of organic solvents compared to conventional chromatographic methods. In this study, a rapid, sensitive, and environmentally friendly method based on ultra‐performance convergence chromatography was developed for the quantification of four major chromones present in the roots of Saposhnikovia divaricata (Turcz.) Schischk. Using this method, the analysis time was significantly shortened compared to conventional high‐performance liquid chromatography techniques. In addition, the influence of cosolvent type, cosolvent ratio, column temperature, system pressure, and flow rate on the peak resolution was investigated. The proposed method was validated in terms of its limits of detection, limits of quantitation, linearity, precision, and accuracy. More specifically, the limits of detection of the four chromones ranged from 0.006 to 0.033 μg/mL, while the limits of quantitation ranged from 0.019 to 0.101 μg/mL. Our method also exhibited a good regression (r² > 0.999), excellent precision (RSD < 0.60%), and acceptable recoveries (99.48–102.89%). Finally, the quantities of these four chromones present in 20 commercial samples from Korea and China were successfully evaluated using the developed method, indicating that the proposed method is suitable for the rapid and accurate quality control of Saposhnikovia divaricata.     

Comparative study on chemical components and anti‐inflammatory effects of Panax notoginseng flower extracted by water and methanol

Methanol and water are commonly used solvents for chemical analysis and traditional decoction, respectively. In the present study, a high‐performance liquid chromatography with ultraviolet detection method was developed to quantify 11 saponins in Panax notoginseng flower extracted by aqueous solution and methanol, and chemical components and anti‐inflammatory effects of these two extracts were compared. The separation of 11 saponins, including notoginsenoside Fc and ginsenoside Rc, was well achieved on a Zorbax SB C18 column. This developed method provides an adequate linearity (r ² > 0.999), repeatability (RSD < 4.26%), inter‐ and intraday variations (RSD < 3.20%) with recovery (94.7–104.1%) of 11 saponins concerned. Our data indicated that ginsenoside biotransformation in PNF was found, when water was used as the extraction solvent, but not methanol. Specifically, the major components of Panax notoginseng flower, ginsenosides Rb1, Rc, Rb2, Rb3, and Rd, can be near completely transformed to the minor components, gypenoside XVII, notoginsenoside Fe, ginsenoside Rd2, notoginsenoside Fd, and ginsenoside F2, respectively. Total protein isolated from Panax notoginseng flower is responsible for this ginsenoside biotransformation. Additionally, methanol extract exerted the stronger anti‐inflammatory effects than water extract in lipopolysaccharide‐induced RAW264.7 cells. This difference in anti‐inflammatory action might be attributed to their chemical difference of saponins.     

Development of a novel hollow‐fiber liquid‐phase microextraction based on oil‐in‐salt and its comparison with conventional one

A novel hollow‐fiber liquid‐phase microextraction based on oil‐in‐salt was proposed and introduced for the simultaneous extraction and enrichment of the main active compounds of hesperidin, honokiol, shikonin, magnolol, emodin, and β,β′‐dimethylacrylshikonin in a formula of Zi‐Cao‐Cheng‐Qi decoction and the single herb, Fructus Aurantii Immaturus , Cortex Magnoliae Officinalis , Radix et Rhizoma , and Lithospermum erythrorhizon , composing the formula prior to their analysis by high‐performance liquid chromatography. The results obtained by the proposed procedure were compared with those obtained by conventional hollow‐fiber liquid‐phase microextraction, and the proposed procedure mechanism was described. In the procedure, a hollow‐fiber segment was first immersed in organic solvent to fill the solvent in the fiber lumen and wall pore, and then the fiber was again immersed into sodium chloride solution to cover a thin salt membrane on the fiber wall pore filling organic solvent. Under the optimum conditions, the enrichment factors of the analytes were 0.6–109.4, linearities were 0.002–12 μg/mL with r ² ≥ 0.9950, detection limits were 0.6–12 ng/mL, respectively. The results showed that oil‐in‐salt hollow‐fiber liquid‐phase microextraction is a simple and effective sample pretreatment procedure and suitable for the simultaneous extraction and concentration of trace‐level active compounds in traditional Chinese medicine.     

Simultaneous determination of acyclovir,ganciclovir, and (R)‐9‐[4‐hydroxy‐2‐(hydroxymethyl)butyl]guanine in human plasma using high‐performance liquid chromatography

Acyclovir, ganciclovir and (R)‐9‐[4‐hydroxy‐2‐(hydroxymethyl)butyl]guanine are active in vitro against the Epstein–Barr virus (EBV) but their in vivo anti‐EBV activity is not well understood. We developed a novel, sensitive high‐performance liquid chromatography assay with ultraviolet detection for measuring acyclovir, ganciclovir and (R)‐9‐[4‐hydroxy‐2‐(hydroxymethyl)butyl]guanine in human plasma to identify quantitative relationships between in vitro anti‐EBV activity and therapeutic response. Characteristics of the assay include a low plasma volume (200 µL), perchloric acid protein precipitation, use of penciclovir as the internal standard, run times less than 8 min and a 50 ng/mL lower limit of quantification. The within‐ and between‐assay variability is 0.7–4.8 and 1.0–7.9%, respectively. Accuracy for all three drugs ranges from 89.5 to 106.4% for four quality controls (50, 100, 1000 and 10,000 ng/mL). This assay supports pharmacokinetic and pharmacodynamic studies of candidate anti‐EBV drugs in children and adults with EBV infections. Copyright © 2009 John Wiley & Sons, Ltd.