C18 Column (c18 + column)

Distribution by Scientific Domains
Chemistry97%
Medical Sciences2%

Kinds of C18 Column

  • acquity uplc beh c18 column
  • beh c18 column
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  • luna c18 column
  • ods c18 column
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  • reversed-phase c18 column
  • uplc beh c18 column
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    Selected Abstracts

    The Use of Silver Solid Amalgam Working Electrode for Determination of Nitrophenols by HPLC with Electrochemical Detection

    ELECTROANALYSIS, Issue 3-5 2009
    Ales Danhel
    Abstract The use of a silver solid amalgam working electrode for HPLC with electrochemical detection has been investigated. The thin-layer and wall-jet detectors based on this electrode were constructed and applied for the determination of a mixture of nitrophenols. The optimal separation and detection conditions for the determination of 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol and 2-methoxy-5-nitrophenol in mixture were found using RP-HPLC at Nova-Pack C18 column and amperometric detection with the above mentioned detectors. It has been proved that the silver solid amalgam electrode is a suitable working electrode for HPLC-ED and provides sufficient sensitivity for determination of tested nitrophenols. [source]

    Simultaneous determination of chlorinated bacteriostats in cosmetic and pharmaceutical products

    INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 6 2005
    L.-H. Wang
    A high-performance liquid chromatography method has been developed for simultaneous determination of triclosan (2,4,4-trichloro-2-hydroxydiphenyl ether) and triclocarban (3,4,4-trichlorocarbanilide) in cosmetic and pharmaceutical products. The two compounds could be separated on a Nucleosil C18 column and eluted with acetonitrile and water (70:30, v/v) as the mobile phase and detected with a differential refractive index detector. The retention times of triclosan and triclocarban were 5.81 and 2.99 min, respectively. The results obtained were in good agreement with those obtained by a differential pulse voltammetric method. [source]

    Quantitative analysis of MRP-8 in gingival crevicular fluid in periodontal health and disease using microbore HPLC

    JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 12 2001
    Fionnuala T. Lundy
    Abstract Background: The protein components of GCF can be separated by reverse-phase microbore HPLC on a C18 column with detection on the basis of 214 nm absorbance. A single major symmetrical protein peak eluting with a retention time of 26 min (50% acetonitrile) was evident in gingival crevicular fluid (GCF) from periodontitis patients but not in healthy GCF. This protein was identified as human MRP-8 by N-terminal amino acid sequencing and liquid chromotography quadropole mass spectrometry. Aims: To quantify the amount of MRP-8 detectable in GCF from individual healthy, gingivitis and periodontitis affected sites and to study the relationship, if any, between the levels of this responsive protein and periodontal health and disease. Methods: GCF was sampled (30 s) from healthy, gingivitis, and periodontitis sites in peridontitis subjects (n=15) and from controls (n=5) with clinically healthy gingiva and no periodontitis. Purified MRP-8 was sequenced by Edmann degradation and the phenylthiohydantoin (PTH) amino acid yield determined (by comparison of peak area with external PTH amino acid standards). This value was subsequently used to calculate the relative amount of protein in the peak eluting with a retention time of 26.0 min (MRP-8) in individual GCF chromatograms. Results: Higher levels of MRP-8 were detected in inflammatory sites: periodontitis 457.0 (281.0) ng; gingivitis 413.5 (394.5) ng compared with periodontally healthy sites in diseased subjects 14.6 (14.3) ng and in controls 18.6 (18.5) ng, p=0.003. There was at least 20-fold more MRP-8 in the inflammatory compared with the healthy sites studied. Conclusions: The preliminary data indicate that MRP-8 is present in GCF, with significantly greater amounts present at diseased than healthy sites. A systematic study of the relationship of this protein to periodontal disease could prove useful in further clarifying whether MRP-8 could be a reliable GCF biomarker of gingivitis and periodontitis. Zusammenfassung Grundlagen: Der Proteingehalt des GCF, abgetrennt werden mit einer reversphasigen Microbore-HPLC auf einer C18-Säule mit Detektion auf der Basis der Absorption von 214 nm. Ein einziges symmetrisches Protein-Hauptpeak-Eluat, der mit einer Retentionszeit von 26 Minuten eluiert wurde (50% Acetonnitril) war in gingivalen Sulkusfluid (GCF) von Parodontitispatienten deutlich sichtbar, jedoch nicht im GCF von Gesunden. Dieses Protein wurde mitels N-terminaler Aminosären-Sequenzierung und Flüssigkeits-Chromatographie mit Quadropol-Massenspektrometrie als humanes MRP-8 identifiziert. Ziele: Quantifizierung der Menge an MRP-8, die im GCF von gesunden Personen, Patienten mit Gingivitis und mit Parodontitis nachweisbar ist und Studieren der eventuell möglichen Beziehungen zwischen den Titern dieses Reaktionsproteins und parodontaler Gesundheit bzw. Erkrankung. Methoden: Bei Parodontitispatienten (n=15) wurde das GCF von gesunden Bereichen, sowie von Stellen mit Gingivitis und Parodontitis gewonnen (30 Sek.) sowie bei Kontrollpersonen (n=5) mit klinisch gesunder Gingiva und ohne Parodontitis. Das gereinigte MRP-8 wurde mittels Edman-Degradierung Sequenziert und der Phenyl-Thiohydantoin (PTH) Aminosäure-Yield bestimmt (durch Vergleich der Peakbereiche mit externen PTH Aminosäurestandards). Darauffolgend wurde dieser Wert verwendet, um die relative Menge des Proteins im Peak-Eluat mit einer Retentionszeit von 26.0 Min. (MRP-8) in den individuellen Chromatogrammen zu berechnen. Ergebnisse: An entzündeten Stellen wurden höhere Titer von MRP-8 nachgewiesen: Parodontitis 457.0 (281.0) ng; Gingivitis 413.5 (394.5) ng verglichen mit parodontal gesunden Stellen bei erkrankten Patienten 14.6 (14.3) ng und den Kontrollen 18.6 (18.5) ng, p=0.003. An den entzündeten Stellen gab es im Vergleich mit den gesunden Stellen wenigstens 20 mal mehr MRP-8. Schlußfolgerungen: Die vorläufigen Daten zeigen, daß MRP-8 im GCF vorhanden ist und an erkrankten Stellen signifikant höhere Mengen vorhanden sind, als an gesunden Stellen. Eine systematische Studie der Beziehung dieses Proteins zur Parodondalerkrankung könnte sich als nützlich erweisen, um des weiteren zu klären, ob MRP-8 eine verläßlicher Biomarker für Gingivitis und Parodontitis ist. Résumé Origine: Les composants proéiques du fluide gingival peuvent être séparés par HPLC microbore en phase inverse sur une colonne C18 avec une détection sur une base d'absorption de 214 nm. Un unique pic majeur symétrique ayant un temps de rétention de 26 min (50% acetonitrile) était manifeste dans le fluide gingival (GCF) des patients atteints de parodontite, mais pas chez les patients sans. Cette protéine fut identifiée comme étant l'MRP-8 humaine après séquençage de l'acide aminé N terminal et spectrométrie de masse quadropole par chromatographie liquide. But: L'objectif est de quantifier la quantité de MRP-8 détectable dans le GCF de site sains, atteints de gingivite ou de parodontite et d'étudier, s'il y en a, la relation entre les niveaux de cette réponse protéique et la santé et la maladie parodontale. Méthodes: Le GCF frut prélevé (30 s) dans des sites sains, atteints de gingivite ou de parodontite, chez des sujets atteints de parodontite (n=15) ou chez des contrôles (n=5), ayant une gencive cliniquement saine sans parodontite. Le MRP-8 purifié fut séquencé par dégradation d'Edmann et le débit d'acide aminé phenylthiohydantoine (PTH) déterminé (par comparaison avec la surface de pic avec des standards d'acide aminé PTH externe). Cette valeur fut ensuite utilisée pour calculer la quantité relative de protéine dans le pic avec un temps de rétention de 26.0 mn (MRP-8) sur des chromatogrammes individuels de GCF. Résultats: De plus hauts niveaux de MRP-8 étaints détectés dans les sites inflammatoires: Parodontite 457.0 (281.0) ng; gingivite 413.5 (394.5) ng par rapport aux sites sains des sujets malades 14.6 (14.3) ng et des sujets contrôles 18.6 (18.5) ng, p=0.003. Il y avait au moins 20× plus de MRP-8 dans les sites inflammatoires par rapport au sites sains. Conclusions: Les données préliminaires indiquent que la MRP-8 est présente dans le GCF, en quantité significativement plus importante dans les sites malades. Une étude systèmatique de la relation entre cette protéine et la maladie parodontale pourrait se révéler utile pour encore plus expliciter si MRP-8 pourrait être un biomarqueur fiable du GCF des gingivites et des parodontites. [source]

    Determination of glycyrrhetic acid in human plasma by HPLC-MS method and investigation of its pharmacokinetics

    JOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 3 2008
    W.-J. Zhao PhD
    Summary Objective:, To develop a high performance liquid chromatography mass spectrometry (HPLC-MS) method for the determination of the glycyrrhetic acid (GA) in human plasma and for the investigation of its pharmacokinetics after the oral administration of 150 mg diammonium glycyrrhizinate test and reference capsule formulations. Methods:, The GA in plasma was extracted with ethyl acetate, separated on a C18 column with a mobile phase of methanol (5 mmol/L ammonium acetate),water (85 : 15, V/V) and analysed using a MS detector. Ursolic acid (UA) was used as internal standard. The target ions were m/z 469·5 for GA and m/z 455·6 for UA, the fragment voltages were 200 V and 100 V for GA and UA respectively. Results:, The calibration curve was linear over the range of 0·5,200 ng/mL (r = 0·9974). The limit of quantification for GA in plasma was 0·5 ng/mL, the recovery was 76·0,80·0%, and the inter- and intra-day relative standard deviations (RSD) were <12%. The pharmacokinetic parameters of GA after a single dose of 150 mg diammonium glycyrrhizinate test and reference were as follows: the half life (t1/2) 9·65 ± 3·54 h and 9·46 ± 2·85 h, the time to peak concentration (Tmax) 10·95 ± 1·32 h and 11·00 ± 1·30 h, the peak concentration (Cmax) 95·57 ± 43·06 ng/mL and 103·89 ± 49·24 ng/mL; the area under time-concentration curve (AUC0,48 and AUC0,,) 1281·84 ± 527·11 ng·h/mL and 1367·74 ± 563·27 ng·h/mL, 1314·32 ± 566·40 ng·h/mL and 1396·97 ± 630·06 ng·h/mL. The relative bioavailability of diammonium glycyrrhizinate capsule was 98·88 ± 12·98%. Conclusion:, The assay was sensitive, accurate and convenient, and can be used for the determination of GA in human plasma. Comparison of the bioavailability and pharmacokinetic profile of GA indicated that the test and reference capsules were bioequivalent. [source]

    Validation of an LC,MS Method for the Detection and Quantification of BZP and TFMPP and their Hydroxylated Metabolites in Human Plasma and its Application to the Pharmacokinetic Study of TFMPP in Humans,

    JOURNAL OF FORENSIC SCIENCES, Issue 5 2010
    Ushtana Antia M.Sc.
    Abstract:, An LC,MS method was developed for benzylpiperazine (BZP) and trifluoromethylphenylpiperazine (TFMPP), constituents of "party pills" or "legal herbal highs," and their metabolites in human blood plasma. Compounds were resolved using a mixture of ammonium formate (pH 4.5, 0.01 M) and acetonitrile (flow rate of 1.0 mL/min) with a C18 column. Calibration curves were linear from 1 to 50 ng/mL (R2 > 0.99); the lower limit of quantification (LLOQ) was 5 ng/mL; the accuracy was >90%; the intra- and interday relative standard deviations (R.S.D) were <5% and <10%, respectively. Human plasma concentrations of TFMPP were measured in blood samples taken from healthy adults (n = 6) over 24 h following a 60-mg oral dose of TFMPP: these peaked at 24.10 ng/mL (±1.8 ng/mL) (Cmax) after 90 min (Tmax). Plasma concentrations of 1-(3-trifluoromethyl-4-hydroxyphenyl) piperazine peaked at 20.2 ng/mL (±4.6 ng/mL) after 90 min. TFMPP had two disposition phases (t½ = 2.04 h (±0.19 h) and 5.95 h (±1.63 h). Apparent clearance (Cl/F) was 384 L/h (±45 L/h). [source]

    Synthesis of 3,7,8- 15N3 -N1 -(, -D- erythro -pentofuranosyl)-5-guanidinohydantoin

    JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 14 2003
    Hongbin Yu
    Abstract 3,7,8- 15N3 -N1 -(, -D- erythro -pentofuranosyl)-5-guanidinohydantoin was synthesized from the oxidation of 1,7,NH2 - 15N3 -8-oxo-7,8-dihydro-2,-deoxyguanosine with 2 equivalents of Ir(IV) in pH 4.5 potassium phosphate buffer. The synthesis of 1,7,NH2 - 15N3 -8-oxo-7,8-dihydro-2,-deoxyguanosine started with bromination of 1,7,NH2 - 15N3 -2,-deoxyguanosine. The resulting 1,7,NH2 - 15N3 -8-bromo-7,8-dihydro-2,-deoxyguanosine reacted with sodium benzyloxide to afford 1,7,NH2 - 15N3 -8-benzyloxy-7,8-dihydro-2,-deoxyguanosine. Subsequent catalytic transfer hydrogenation of 1,7,NH2 - 15N3 -8-benzyloxy-7,8-dihydro-2,-deoxyguanosine with cyclohexene and 10% Pd/C yielded 1,7,NH2 - 15N3 -8-oxo-7,8-dihydro-2,-deoxyguanosine. Purification of 3,7,8- 15N3 -N1 -(, -D- erythro -pentofuranosyl)-5-guanidinohydantoin was first carried out on a C18 column and the product was further purified on a graphite column. ESI-MS was used to confirm the identity and to determine the isotopic purity of all the labeled compounds. The isotopic purity of 3,7,8- 15N3 -N1 -(, -D- erythro -pentofuranosyl)-5-guanidinohydantoin was 99.4 atom% based on LC-MS measurements. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Quantitative analysis of EO9 (apaziquone) and its metabolite EO5a in human plasma by high-performance liquid chromatography under basic conditions coupled to electrospray tandem mass spectrometry

    JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 10 2006
    Liia D. Vainchtein
    A sensitive and specific LC-MS/MS assay for the quantitative determination of EO9 and its metabolite EO5a is presented. A 200-µl human plasma aliquot was spiked with a mixture of deuterated internal standards EO9- d3 and EO5a- d4 and extracted with 1.25 ml ethyl acetate. Dried extracts were reconstituted in 0.1 M ammonium acetate,methanol (7 : 3, v/v) and 25 µl-volumes were injected into the HPLC system. Separation was achieved on a 150 × 2.1 mm C18 column using an alkaline eluent (1 mM ammonium hydroxide,methanol (gradient system)). Detection was performed by positive ion electrospray followed by tandem mass spectrometry. The assay quantifies a range from 5 to 2500 ng/ml for EO9 and from 10 to 2500 ng/ml EO5a using 200 µl of human plasma samples. Validation results demonstrate that EO9 and EO5a concentrations can be accurately and precisely quantified in human plasma. This assay will be used to support clinical pharmacologic studies with EO9. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Combination of liquid chromatography/tandem mass spectrometry and gas chromatography/mass spectrometry for the detection of 21 anabolic steroid residues in bovine urine

    JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 6 2005
    Christof Van Poucke
    Abstract For the detection of anabolic steroid residues in bovine urine, a highly sensitive liquid chromatographic/electrospray ionization tandem mass spectrometric (LC/ESI-MS/MS) method was developed using both positive and negative ionization. For four compounds the ESI mode was not sensitive enough and gas chromatographic/mass spectrometric GC/MS detection was therefore still necessary as a complementary method. The sample clean-up consisted of solid-phase extraction (SPE) on a C18 column followed by enzymatic hydrolysis and a second solid-phase extraction on a combination of a C18 and a NH2 column. After this last SPE clean-up, the eluate was split into two equal aliquots. One aliquot was further purified and after derivatization used for GC/MS analysis. The other aliquot was analyzed with LC/MS/MS in both ESI+ and ESI, modes. The method was validated according to the European Commission Decision 2002/657/EC. Decision limits (CC,) were between 0.16 and 1 ng ml,1 for the compounds detected with the LC/MS/MS method. The developed method is used in routine analysis in our laboratory. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Development and validation of a liquid chromatographic/tandem mass spectrometric assay for the quantitation of nucleoside HIV reverse transcriptase inhibitors in biological matrices

    JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2005
    Séverine Compain
    Abstract Besides liquid chromatographic (LC)/UV methods adapted to therapeutic drug monitoring, there is still a need for more powerful techniques that can be used for pharmacological research and clinical purposes. We developed an LC method coupled with tandem mass spectrometry (MS/MS) to separate, detect and quantify with high sensitivity the nucleoside analogues used in multitherapies (zidovudine, stavudine, zalcitabine, didanosine, lamivudine and abacavir) in plasma and in the intracellular medium. We worked on two essential issues: (i) the need to use two ionization modes in order to achieve the best sensitivity, which leads to the optimization of the chromatographic separation of drugs detected in the positive ionization mode and drugs detected in the negative ionization mode, and (ii) the need to optimize the extraction step in order to enhance sample recovery. The peripheral blood mononuclear cells were lysed in Tris buffer,MeOH. A clean-up procedure was performed by solid-phase extraction only for plasma samples. The LC separation was carried out on a Zorbax Stable Bond C18 column followed by MS/MS analysis after electrospray ionization in either the negative or positive mode. The positive ionization mode was applied at the beginning of the run to detect zalcitabine and lamivudine, then the ionization mode was changed to negative for the detection of didanosine, stavudine, internal standard and zidovudine. The calibration range for all the analytes was 0.5,200 ng ml,1. The recoveries were between 64 and 90%, with coefficients of variation (CVs) lower than 15%. The inaccuracy (bias) was ±15% with CVs always lower than 12%. The analytes were stable at room temperature and in the extraction solvent for at least 24 h, after storage at ,80 °C for 3 months, after three freeze,thaw cycles and in the injection solvent after 48 h at 4 °C. Together with the measurement of intracellular triphosphorylated metabolites thanks to the powerful plasma and intracellular assay method for intact drugs, it is possible to describe the behaviour of nucleoside analogues against HIV through plasma pharmacokinetics, cell membrane diffusion including drug transport involvement, and also the intracellular metabolism. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Simultaneous quantification of cyclophosphamide, 4-hydroxycyclophosphamide, N,N,,N, -triethylenethiophosphoramide (thiotepa) and N,N,,N, -triethylenephosphoramide (tepa) in human plasma by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry

    JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 3 2004
    Milly E. de Jonge
    Abstract The alkylating agents cyclophosphamide (CP) and N, N,, N, -triethylenethiophosphoramide (thiotepa) are often co-administered in high-dose chemotherapy regimens. Since these regimens can be complicated by the occurrence of severe and sometimes life-threatening toxicities, pharmacokinetically guided administration of these compounds, to reduce variability in exposure, may lead to improved tolerability. For rapid dose adaptations during a chemotherapy course, we have developed and validated an assay, using liquid chromatography coupled with electrospray tandem mass spectrometry (LC/MS/MS), for the routine quantification of CP, thiotepa and their respective active metabolites 4-hydroxycyclophosphamide (4OHCP) and N, N,, N, -triethylenephosphoramide (tepa) in plasma. Because of the instability of 4OHCP in plasma, the compound is derivatized with semicarbazide (SCZ) immediately after sample collection and quantified as 4OHCP-SCZ. Sample pretreatment consisted of protein precipitation with a mixture of methanol and acetronitrile using 100 µl of plasma. Chromatographic separation was performed on an Zorbax Extend C18 column (150 × 2.1 mm i.d., particle size 5 µm), with a quick gradient using 1 mM ammonia solution and acetonitrile, at a flow-rate of 0.4 ml min,1. The analytical run time was 10 min. The triple quadrupole mass spectrometer was operating in the positive ion mode and multiple reaction monitoring was used for drug quantification. The method was validated over the concentration ranges 200,40 000 ng ml,1 for CP, 50,5000 ng ml,1 for 4OHCP-SCZ and 5,2500 ng ml,1 for thiotepa and tepa, using 100 µl of human plasma. These dynamic concentration ranges proved to be relevant in daily practice. Hexamethylphosphoramide was used as an internal standard. The coefficients of variation were <12% for both intra-day and inter-day precisions for each compound. Mean accuracies were also between the designated limits (±15%). This robust and rapid LC/MS/MS assay is now successfully applied for routine therapeutic drug monitoring of CP, thiotepa and their metabolites in our hospital. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    High-performance liquid chromatography determination of hydrastine and berberine in dietary supplements containing goldenseal

    JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2001
    Ehab A. Abourashed
    Abstract Goldenseal (Hydrastis canadensis L., Ranunculaceae) is an ingredient of various dietary supplements intended for enhancing general body immunity. Many goldenseal products are currently available in the United States, either alone or in combination with echinacea. In most products, the content of the main active alkaloids of goldenseal, hydrastine and berberine, is not indicated on the label. A high-performance liquid chromatography (HPLC) method has been developed for the detection and quantification of hydrastine and berberine in a number of products obtained from the United States market. The method uses a Phenomenex® Luna C18 column, a mobile phase consisting of solvent A (100 mM sodium acetate/acetic acid, pH 4.0) and solvent B (acetonitrile/methanol; 90/10, v/v). Elution was run at a flow rate of 1.0 mL/min, with a linear gradient of 80, 40% A in B over 20 min and ultraviolet detection at 290 nm. A wide range of content variation was observed for both alkaloids in the tested samples. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:817,822, 2001 [source]

    Simultaneous determination of yohimbine, sildenafil, vardenafil and tadalafil in dietary supplements using high-performance liquid chromatography-tandem mass spectrometry

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2010
    Ying Zhang
    Abstract A simple and sensitive method was developed for determination of illegal adulterants (yohimbine, sildenafil, vardenafil and tadalafil) in dietary supplements by HPLC-MS/MS. The separation was achieved on a C18 column with the mobile phase consisting of acetonitrile and 0.1% acetic acid aqueous solution with a gradient elution at a flow rate of 0.5,mL/min. The analytes were quantified and identified by two characteristic transitions using the multiple-reaction monitoring mode. The recoveries of the analytes ranged from 77.5 to 109.3% with the RSD less than 8.1% (n=6). The method has been successfully applied to screen illegal adulterations of natural dietary supplements. [source]

    Identification and determination of the saikosaponins in Radix bupleuri by accelerated solvent extraction combined with rapid-resolution LC-MS

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2010
    Yun-Yun Yang
    Abstract A method based on accelerated solvent extraction combined with rapid-resolution LC,MS for efficient extraction, rapid separation, online identification and accurate determination of the saikosaponins (SSs) in Radix bupleuri (RB) was developed. The RB samples were extracted by accelerated solvent extraction using 70% aqueous ethanol v/v as solvent, at a temperature of 120°C and pressure of 100,bar, with 10,min of static extraction time and three extraction cycles. Rapid-resolution LC separation was performed by using a C18 column at gradient elution of water (containing 0.5% formic acid) and acetonitrile, and the major constituents were well separated within 20,min. A TOF-MS and an IT-MS were used for online identification of the major constituents, and 27 SSs were identified or tentatively identified. Five major bioactive SSs (SSa, SSc, SSd, 6,- O -acetyl-SSa and 6,- O -acetyl-SSd) with obvious peak areas and good resolution were chosen as benchmark substances, and a triple quadrupole MS operating in multiple-reaction monitoring mode was used for their quantitative analysis. A total of 16 RB samples from different regions of China were analyzed. The results indicated that the method was rapid, efficient, accurate and suitable for use in the quality control of RB. [source]

    Determination of multicomponent contents in Calculus bovis by ultra-performance liquid chromatography,evaporative light scattering detection and its application for quality control

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 10 2010
    Weijun Kong
    Abstract A fast ultra-performance liquid chromatography,evaporative light scattering detection (UPLC-ELSD) method was established for simultaneous quantification of seven components in natural Calculus bovis (C. bovis) and its substitutes or spurious breeds. On a Waters Acquity UPLC® BEH C18 column, seven analytes were efficiently separated using 0.2% aqueous formic acid,acetonitrile as the mobile phase in a gradient program. The evaporator tube temperature of ELSD was set at 100°C with the nebulizing gas flow-rate of 1.9,L/min. The results showed that this established UPLC-ELSD method was validated to be sensitive, precise and accurate with the LODs of seven analytes at 2,11,ng, and the overall intra-day and inter-day variations less than 3.0%. The recovery of the method was in the range of 97.8,101.6%, with RSD less than 3.0%. Further results of PCA on the contents of seven investigated analytes suggested that compounds of cholic acid, deoxycholic acid and chenodeoxycholic acid or cholesterol should be added as chemical markers to UPLC analysis of C. bovis samples for quality control and to discriminate natural C. bovis sample and its substitutes or some spurious breeds, then normalize the use of natural C. bovis and ensure its clinical efficacy. [source]

    Ionic liquids as mobile phase additives for high-performance liquid chromatography separation of phenoxy acid herbicides and phenols

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 23-24 2009
    Xialin Hu
    Abstract In this present study, 1-butyl-3-methylimidazolium chloride ([C4MIM]Cl), 1-octyl-3-methylimidazolium chloride ([C8MIM]Cl), and 1-decyl-3-methylimidazolium chloride ([C10MIM]Cl) were adopted as mobile phase additives in the high performance liquid chromatography (HPLC) to simultaneously separate phenoxy acid herbicides and phenols at neutral pH. It was found that by using 20,mM of [C4MIM]Cl, baseline separation and good chromatograms for all the acid compounds were obtained on a normal reversed-phase C18 column. The retention time of the target acid compounds shortened with the increase of the alkyl chain length and the concentrations of ionic liquids, probably due to the delocalization of the positive charge on the imidazolium cation, the repulsion between chlorine ions of ionic liquids and the acid compounds, as well as the stereo-hindrance effect. The mechanism with ionic liquids as mobile additives for the separation of acid compounds was discussed. [source]

    Determination of pKa values of nonsteroidal antiinflammatory drug-oxicams by RP,HPLC and their analysis in pharmaceutical dosage forms

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 17 2009
    Ebru Cubuk Demiralay
    Abstract In this study, pKa values were determined by using the dependence of the capacity factor on the pH of the mobile phase for four ionizable substances, namely, tenoxicam, piroxicam, meloxicam, and naproxen (I.S.). The effect of the mobile phase composition on the ionization constant was studied by measuring the pKa at different ACN concentrations, ranging from 30 to 40%. The adequate condition for the chromatographic determination of these compounds in pharmaceutical dosage forms was established based on the different retention behaviors of the species. An octadecylsilica Nucleosil C18 column (150×4.6 mm, 5 ,m) was used for all the determinations. The chromatographic separation of oxicams was carried out using acetonitrile (ACN)/water at 35% v/v, containing 65 mM phosphoric acid and UV detection at a wavelength of 355 nm. The method developed was successfully applied to the simultaneous determination of these drug compounds in laboratory-prepared mixtures and their commercial pharmaceutical dosage forms. Each analysis requires no longer than 12 min. [source]

    Determination of basic azaarenes in aviation kerosene by solid-phase extraction and HPLC-fluorescence detection

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2009
    Elaine Rocha da Luz
    Abstract SPE in combination with HPLC and fluorescence detection has been used for sensitive determination of six basic azaarenes (7,8-benzoquinoline, 7,9-dimethylbenz[c]acridine, 9-amino-1,2,3,4-tetrahydroacridine, 9-methylacridine, acridine, and dibenz[a,j]acridine) in aviation kerosene (jet fuel). SPE was performed in a single step using a strong cation exchange sorbent. The HPLC system consisted of C18 column with a selected detection program of optimal ,exc and ,em. A gradient elution with ACN and phosphate buffer (pH 6.5) at a flow rate of 1 mL/min allowed efficient and fast separation of azaarenes within 15 min. The LOD and LOQ values (S/N ratio 3:1 and 10:1, respectively) were between 0.0013 and 0.021 and from 0.0044 to 0.072 ng per injection. The calibration curves showed linear behavior from the LOQ to 250 ,g/L (r2 >0.99). For the spiked concentration of 6.0 ,g/L, recoveries were from 92 to 107% for jet fuel samples, except for 9-amino-1,2,3,4-tetrahydroacridine, which presented 68% recovery. The proposed method was applied to the quantification of those six basic azaarenes in one commercial kerosene and in three aviation kerosene samples. The presence of 7,8-benzoquinoline (up to 3.2 ,g/L) and dibenzo[a,j]acridine (up to 6.3 ,g/L) was confirmed in aviation kerosene. [source]

    Rapid simultaneous determination of codeine and morphine in plasma using LC-ESI-MS/MS: Application to a clinical pharmacokinetic study

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2009
    Qiongfeng Liao
    Abstract A rapid and sensitive high-performance LC-MS/MS method was developed and validated for the simultaneous quantification of codeine and its metabolite morphine in human plasma using donepezil as an internal standard (IS). Following a single liquid-liquid extraction with ethyl acetate, the analytes were separated using an isocratic mobile phase on a C18 column and analyzed by MS/MS in the selected reaction monitoring mode using the respective [M+H]+ ions, mass-to-charge ratio (m/z) 300/165 for codeine, m/z 286/165 for morphine and m/z 380/91 for IS. The method exhibited a linear dynamic range of 0.2,100/0.5,250 ng/mL for codeine/morphine in human plasma, respectively. The lower LOQs were 0.2 and 0.5 ng/mL for codeine and its metabolite morphine using 0.5 mL of human plasma. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.0 min for each sample made it possible to analyze more than 300 human plasma samples per day. The validated LC-MS/MS method was applied to a pharmacokinetic study in which healthy Chinese volunteers each received a single oral dose of 30 mg codeine phosphate. [source]

    Simultaneous determination of simvastatin and simvastatin acid in human plasma by LC-MS/MS without polarity switch: Application to a bioequivalence study

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2008
    Bhavin N. Patel
    Abstract A simple, specific and sensitive LC-MS/MS assay for simultaneous determination of simvastatin (SV) and its active ,-hydroxy acid metabolite, simvastatin acid (SVA) in human plasma was developed using a statin analog as internal standard (IS). The method was validated over a dynamic linear range of 0.20,100.00 ng/mL for SV and 0.10,50.00 ng/mL for SVA with correlation coefficient r , 0.9987 and 0.9989, respectively. The analytes and IS were extracted from 500 ,L aliquots of human plasma via liquid-liquid extraction using methyl tert -butyl ether and separated through an Aquasil C18 column (100 mm×2.1 mm, 5 ,m). Detection of analytes and IS was done by MS/MS with a turbo ion spray interface operating in positive ion and selective reaction monitoring acquisition mode. The total chromatographic run time was 3.0 min. Flash freezing of the aqueous phase was an added advantage during liquid-liquid extraction, which considerably reduced time and labour. The method was extensively validated for its accuracy, precision, recovery, stability studies and matrix effect. The method was successfully used for bioequivalence study of 40 mg SV tablet formulation in 12 human subjects under fasting condition. [source]

    Confirmation and determination of carboxylic acids in root exudates using LC,ESI-MS

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 15 2007
    Zuliang Chen
    Abstract Reversed-phase liquid chromatography with UV detection is of limited applicability in the separation and identification of carboxylic acids because of the column's poor separation efficiency and the non-selective nature of the UV detector. To address this issue, RP-LC with electrospray ionization mass spectrometry has been explored for the confirmation and determination of carboxylic acids in plant root exudates, with ESI-MS providing structural information, high selectivity, and high sensitivity. The separation of 10 carboxylic acids (pyruvic, lactic, malonic, maleic, fumaric, succinic, malic, tartaric, trans -aconitic, and citric acid) was performed on a C18 column using an eluent containing 0.1% (v/v) acetic acid within 10 min, where the acidic eluent not only suppressed the ionization of the carboxylic acids to be retained on the column, but was also compatible with ESI-MS detection. In addition, an additional standard was used to overcome the matrix effect. The results showed that peak areas correlated linearly with the concentration of carboxylic acids over the range 0.05,10 mg/L. The detection limits of target acids (signal-to-noise S/N ratio of 3) ranged from 20 to 30 ,g/L. Finally, the proposed method was used for the confirmation and determination of low-molecular-weight carboxylic acids in plant root exudates, and provided a simple analytical procedure, including sample processing, fast separation, and high specificity and sensitivity. [source]

    Simultaneous qualification and quantification of eight triterpenoids in Radix Achyranthis Bidentatae by high-performance liquid chromatography with evaporative light scattering detection and mass spectrometric detection

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 6 2007
    Juan Li
    Abstract An HPLC with evaporative light scattering detection (ELSD) and ESI-MS was established for the simultaneous determination of eight triterpenoids in Radix Achyranthis Bidentatae. The optimal chromatographic conditions were achieved on a Zorbax C18 column by linear gradient elution with 0.08% v/v aqueous formic acid and ACN as the mobile phase at the flow rate of 0.8 mL/min. Temperature for the detector drift tube was set at 101°C and the nitrogen flow rate was 2.8 L/min. The identities of the analytes were accomplished by comparing retention times and mass data with those of reference compounds. The validation of the method included tests of linearity, sensitivity, repeatability, recovery, and stability. All the calibration curves of the eight triterpenoids showed good linear regression (R2 >0.997) within the test ranges. The method provides desirable repeatability with overall intra- and interday variations of less than 4.9%. The obtained recoveries varied between 93.6 and 98.1% while the RSDs were below 3.9% (n = 3). The analysis results indicate that the content of investigated triterpenoids in Radix Achyranthis Bidentatae from different locations was greatly diverse, and the triterpenoids could be used as chemical markers for the discrimination of genuine and ungenuine crude drugs. [source]

    Simultaneous determination of 11 saponins in Panax notoginseng using HPLC-ELSD and pressurized liquid extraction

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2006
    Jian-Bo Wan
    Abstract A new HPLC coupled with evaporative light scattering detection (ELSD) method was developed for simultaneous determination of 11 major triterpene saponins, namely notoginsenoside R1 (1), ginsenosides Rg1 (2), Re (3), Rf (4), Rb1 (5), Rg2 (6), Rc (7), Rb2 (8), Rb3 (9), Rd (10), and Rg3 (11) in Panax notoginseng, a commonly used traditional Chinese medicine (TCM). Pressurized liquid extraction (PLE) was employed for sample preparation, and the analysis was achieved using a Zorbax ODS C18 column eluted with gradient water-ACN in 60 min. The drift tube temperature of ELSD was set at 60°C, and nitrogen flowrate was at 1.4 L/min. The method provided good repeatability and sensitivity for quantification of 11 saponins with overall precision (including intra- and interday) and LOD of less than 2.9% (RSD) and 98 ng, respectively. The validated method was successfully applied to quantify 11 saponins in 28 samples of P. notoginseng collected in different places, which is helpful to control the quality of P. notoginseng and its related products. [source]

    Simple 2D-HPLC using a monolithic silica column for peptide separation

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 10-11 2004
    Hiroshi Kimura
    Abstract Separation of peptides by fast and simple two-dimensional (2D)-HPLC was studied using a monolithic silica column as a second-dimension (2nd-D) column. Every fraction from the first column, 5 cm long (2.1 mm ID) packed with polymer-based cation exchange beads, was subjected to separation in the 2nd-D using an octadecylsilylated (C18) monolithic silica column (4.6 mm ID, 2.5 cm). A capillary-type monolithic silica C18 column (0.1 mm ID, 10 cm) was also employed as a 2nd-D column with split flow/injection. Effluent of the first dimension (1st-D) was directly loaded into an injector loop of 2nd-D HPLC. UV and MS detection were successfully carried out at high linear velocity of mobile phase at 2nd-D using flow splitting for the 4.6 mm ID 2nd-D column, or with direct connection of the capillary column to the MS interface. Two-minute fractionation in the 1st-D, 118-second loading, and 2-second injection by the 2nd-D injector, allowed one minute for gradient separation in the 2nd-D, resulting in a maximum peak capacity of about 700 within 40 min. The use of a capillary column in the 2nd-D led to less solvent consumption and better MS detectability compared to a larger-sized column. This kind of fast and simple 2D-HPLC utilizing monolithic silica columns will be useful for the separation of complex mixtures in a short time. [source]

    Determination of the purity of ampicillin by micellar electrokinetic chromatography and reversed phase liquid chromatography on a monolithic silica column

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 7-8 2004
    Milada Dole, alová
    Abstract A micellar electrokinetic chromatographic (MEKC) method and a fast reversed-phase liquid chromatographic one have been developed for determining the purity of ampicillin. MEKC separation of ampicillin and its related substances was performed with the use of an untreated fused-silica capillary and 40 mM phosphate-borate buffer, pH 7.5 containing 75 mM SDS. The HPLC method employed a monolithic silica C18 column and a mobile phase composed of phosphate buffer, pH 5.2 and ACN, the flow rate being 4.0 mL/min. Both methods were successfully validated. Linearity, relative response factors, limits of quantitation, intermediate precision, and accuracy were evaluated. The methods proved to be fast, reliable, and sufficiently sensitive and, accordingly, well-suited for control of purity of ampicillin substance, injections, and capsules. A combination of both methods can be very useful in the confirmation of impurity profiles. [source]

    Separation and determination of small amounts of sulfur in technical thiophanate-methyl by reversed-phase high-performance liquid chromatography

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 9-10 2003
    R. Nageswara Rao
    Abstract A simple and rapid reversed phase high-performance liquid chromatographic method for separation and determination of elemental sulfur in technical thiophanate-methyl using a reversed-phase C18 column and methanol-water-tetrahydrofuran (90 : 8 : 2 v/v/v) as eluent with UV detection at 254 nm has been developed and validated with respect to accuracy, precision, specificity, linearity range, and limits of detection and quantification. The method was found to be suitable not only for detection but also determination of elemental sulfur at levels of 5×10,9 g. [source]

    Phenolic compounds in the brown seaweed Ascophyllum nodosum: distribution and radical-scavenging activities

    PHYTOCHEMICAL ANALYSIS, Issue 5 2010
    Laetitia Audibert
    Abstract Introduction , Phenolic compounds are metabolites exhibited at high levels in Phaeophyceae. Although several studies have been conducted on total phenol contents, no one to our knowledge has dealt with the contents of phenolic compounds and antioxidant activities on purified fractions. Objective , The purpose of this study was the extraction and purification of phenolic compounds from the brown seaweed Ascophylllum nodosum, to determine both their distribution and their radical-scavenging activities, and to obtain a sufficiently purified oligophenolic fraction to perform an RP-HPLC analysis on molecules with a molecular weight (MW) < 2,kDa. Methodology , Phenolic compounds were separated and purified by liquid,liquid extraction, tangential ultrafiltration and dialysis. Then, the contents of both phenolic compounds and radical-scavenging activities were measured by the Folin,Ciocalteu reagent, and DPPH and ABTS assays. NMR analysis was performed to validate the process. RP-HPLC with a C18 column was performed on the oligophenolic fraction, using a novel method developed in this study. Results , Seven fractions were obtained as a function of polarity and molecular weight. Among them, the fraction containing phenolic compounds with a MW , 50,kDa appeared to be the most active, correlated with the content of phenolic compounds. Conclusion , This work constitutes a step forward in the separation and purification of bioactive phlorotannins and represents a prerequisite for further investigations into their structural characterisation and distribution in A. nodosum. [source]

    Ultrasonic extraction and HPLC determination of anthraquinones, aloe-emodine, emodine, rheine, chrysophanol and physcione, in roots of Polygoni multiflori

    PHYTOCHEMICAL ANALYSIS, Issue 4 2009
    Yue Jiao
    Abstract Introduction Polygoni multiflori, one of traditional Chinese herbal medicines for the treatment of various diseases commonly associated with aging, is known to contain active anthraquinone ingredients. However, the content of the anthraquinones varies among P. multiflori samples with collection season and sites. Thus, simple, reliable and accurate analytical methods for determining of anthraquinones in P. multiflori products are needed for the quality control and pharmacological studies. Objective To develop an HPLC method for the simultaneous determination of five anthraquinones, aloe-emodine, rheine, emodine, chrysophanol and physcione, in the roots of P. multiflori. Methodology Anthraquinones were extracted from the roots of P. multiflori using aqueous alcohol solutions or hot water under ultrasonication. Separation and quantitation of anthraquinones was accomplished using a reversed-phase C18 column with the mobile phase of methanol,water,phosphoric acid (600:400:1), and the detection wavelength of 254 nm. Results Seventy per cent aqueous ethanol showed the highest extraction efficiency for anthraquinones from roots of P. multiflori when compared with four other extraction solvents tested. All calibration curves were linear over the concentration range tested with the square of correlation coefficients >0.999. The detection limits (S/N = 3) were 0.89, 1.1, 1.6, 1.7 and 2.0 ng for chrysophanol, aloe-emodine, rheine, emodine and physcione, respectively. Emodine and physcione were found in the samples tested at concentrations of 0.341 and 0.197 mg/g, respectively. Conclusion The described HPLC methods are simple, accurate and selective techniques for separation and quantification of anthraquinones in roots of P. multiflori and other plant samples. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Analysis of pharmaceutical samples of Resina Draconis by HPLC-PAD

    PHYTOCHEMICAL ANALYSIS, Issue 6 2008
    Wenjun Gong
    Abstract Introduction: The quality evaluation of traditional Chinese medicine (TCM) represents a particular challenge owing to the complexity of the matrix, which renders separation and identification of the individual components extremely difficult. In recent years, fingerprinting of TCMs has played a dominant role in quality control. Resina Draconis was authorised as a new TCM in 1991, but a satisfactory HPLC fingerprint method for this preparation has not yet been published. Objective: To develop a simple and reliable protocol for the quality control of Resina Draconis using an HPLC-PAD method. Methodology: The TCM was extracted with methanol at room temperature. Chromatography was carried out using a Lichrospher C18 column eluted with a linear gradient of acetonitrile (A) and water containing 0.1% phosphoric acid (B), initially at 30:70 (A:B) and changing to 60:40 in 90 min. UV (PAD) spectra were acquired in the range 210,400 nm. Results: Four chromatograms of samples of Resina Draconis obtained from different pharmaceutical factories showed 20 peaks in common. The average chromatogram was taken as a template from which the correlation coefficients and cosine ratios of the samples were determined. Whereas the contents of individual components in each sample were different, overall the samples were extremely similar one to another, and the products from different pharmaceutical factories were consistent. Conclusion: A reliable and validated HPLC method has been developed for the fingerprint analysis of Resina Draconis that can be applied for the quality control of this TCM. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    A reversed-phase high-performance liquid chromatographic method for the determination of aloesin, aloeresin a and anthraquinone in Aloe ferox

    PHYTOCHEMICAL ANALYSIS, Issue 2 2008
    Michael Zahn
    Abstract A reversed-phase HPLC method for the quantification of aloesin, aloeresin a and anthraquinone (as barbaloin) in Aloe ferox Miller and aloe-related products has been developed and validated. The method utilized a C18 column with a water,methanol gradient and UV detection at 297 nm. The method validation included linearity, accuracy, precision, limit of detection, limit of quantitation, specificity and standard solution stability. The method showed good linearity (r > 0.99 for all components) and recovery (>85% for all components). The detection and quantitation limits for barbaloin were determined to be 0.02 and 0.1 ppm at signal-to-noise ratios of approximately 3:1 and 10:1, respectively. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Analysis of Rhizoma Polygoni Cuspidati by HPLC and HPLC-ESI/MS

    PHYTOCHEMICAL ANALYSIS, Issue 5 2007
    Tao Yi
    Abstract An HPLC method with photodiode array detection (PAD) and ESI/MS detection was developed for the qualitative and quantitative analysis of the major chemical constituents of the dried rhizome of Polygonum cuspidatum Sieb. et Zucc. (Rhizoma Polygoni Cuspidati; Chinese name Hu-Zhang). Based on the chromatographic separation on an Altima C18 column using 0.5% aqueous acetic acid and acetonitrile as the mobile phase, nine compounds, including stilbenes, stilbene glucosides, anthraquinones and anthraquinone glucosides, were identified by online ESI/MS analysis and seven were quantified by HPLC-PAD. A full validation of the method including sensitivity, linearity, repeatability and recovery was conducted. Linear calibration was achieved over the concentration range 1,200 mg/L with R2 > 0.999, whilst the limits of detection ranged from 0.51 to 1.57 ng. Repeatability was evaluated by intra- and inter-day assays and the RSD value was within 1.79%. Recoveries of the quantified compounds were within the range 96.0,100.1% with RSD values of less than 2.2%. Five samples of Rhizoma Polygoni Cuspidati from different regions were analysed using the developed method. The major constituents piceid, resveratrol, emodin-8- O - , - d -glucoside and emodin were selected to provide an index for the quality assessment of the herbal drug. Copyright © 2007 John Wiley & Sons, Ltd. [source]