DOCSLIB.ORG

Lab.2. Thin Layer Chromatography

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Lab.2. Thin Layer Chromatography Lab.2. Thin layer chromatography Key words: Separation techniques, compounds and their physicochemical properties (molecular volume/size, polarity, molecular interactions), mobile phase, stationary phase, liquid chromatography, thin layer chromatography, column chromatography, retardation factor, elution, chromatogram development, qualitative and quantitative analysis with chromatography techniques, eluotropic series, elution strength. Literature: D.A. Skoog, F.J. Holler, T.A. Nieman: Principles of Instrumental Analysis; 637 - 718 Search on www pages “Thin-layer chromatography principles” For example: MIT Digital Lab Techniques Manual you find on http://www.youtube.com/watch?v=e99nsCAsJrw&feature=player_detailpage Basic equipment for modern thin layer chromatography: www.camag.com/downloads/free/brochures/CAMAG-basic-equipment-08.pdf other examples: en.wikipedia.org/wiki/Thin_layer_chromatography www.chemguide.co.uk/analysis/chromatography/thinlayer.html www.wellesley.edu/Chemistry/chem211lab/Orgo_Lab_Manual/Appendix/Techniques/TLC/th in_layer_chrom.html Theoretical background Chromatography is the separation technique in which separated solutes are distributed between two phases: stationary and mobile. The first phase can pose a layer of sorbent/adsorbent (0.1 to 0.25 mm in thickness) fixed to a carrier plate made of glass, plastic or aluminum (used in technique named as thin-layer chromatography, TLC) or placed inside of a steel tube as a column bed (used in a technique named as high-performance liquid chromatography, HPLC, or generally in column liquid chromatography, LC). The second phase, mentioned above, constitute liquid or gas phase. Various organic (e.g. methanol, hexane, acetone) and inorganic (e.g. water) solvents or their mixtures (e.g. acetone and Lab.2. Thin layer chromatography hexane, methanol and water) can be used as the mobile phases. So each chromatographic system consists of: a) stationary phase, b) mobile phase, c) mixture of components to be separated. A solution of the component mixture is usually introduced into the chromatographic system by injection (in HPLC or classical column chromatography in entrance to the column) or by spotting/application onto start line (in TLC). In column chromatography the mobile phase is pumped through the adsorbent bed or its flow is caused by gravitation as it is demonstrated in Fig 1A. In thin layer chromatography mobile phase is driven into movement by capillary forces (solvent wets adsorbent layer on the chromatographic plate by capillary forces) as it is demonstrated in Fig 1B. Under such circumstances mixture components migrate along the stationary phase (adsorbent) according to the direction of flow of the mobile phase. Mobile phase Station A B ary phase Chromatographic plate Valve Chromatographic chamber Mobile phase Fig. 1. (A) Classical column chromatography, (B) chromatogram development in conventional chamber (in cuboid vessel) Migration velocities of mixture components are slower from that o the mobile phase. It is because of time, which separated molecules spend in the stationary phase. Arrangement of solute zones on the chromatographic plate after chromatogram development is demonstrated in Fig. 2. Lab.2. Thin layer chromatography Solvent front Start line Fig. 2. Thin layer chromatogram of dyes, 1 and 10 – dye mixture, 2 – 9 single dyes The time the separated molecules spend in the stationary phase depends on their interactions with stationary and mobile phases. It means the mixture components can be separated in the chromatographic system if they demonstrate different migration distances, i.e. if they show different energy of molecular interactions with components of the chromatographic system. Following molecular interactions of solutes with elements of stationary and mobile phases can take place in any chromatographic system: hydrogen bond, dipole – dipole, dipole – induced dipole, ion – dipole, instantaneous dipole – induced dipole (London dispersion forces), ion – ion. The stationary phase 1. Silica gel Silica gel is composed of silicon dioxide (silica). The silicon atoms are bonded via oxygen atoms in a giant covalent structure. However, at the surface of the silica gel -OH groups are attached to the silicon atoms. So, on the surface of silica gel Si-O-H groups are present instead of Si-O-Si ones. This makes silica surface very polar. Fig. 3 shows the model of a small part of the silica surface. Lab.2. Thin layer chromatography Fig.3. A simplified model of silica gel surface There are also silica based adsorbents, which are non-polar, i.e. chemically modified silica. Modified silica gel is formed by chemical reaction of its surface with e.g. trichlorooctadecylsilane or other reagents. Thus the surface polarity decreases and then its hydrophobicity increases. 2. Aluminum oxide Aluminum oxide (Al2O3) is another adsorbent, which is often used as stationary phase in laboratory practice. TLC aluminum oxide plates usually comprise neutral or basic aluminum oxide. These kinds of plates provide distinct separation features with regard to a pH range of the mobile phase used. Under aqueous conditions basic compounds can be well separated with basic aluminum oxide plates, while neutral compounds can be successfully separated with neutral aluminum oxide ones. 3. Cellulose Cellulose is the next adsorbent used as a stationary phase in chromatography systems, especially in TLC. Macromolecules consisting of D-glucose units coupled -glycosidically at positions 1 and 4 by oxygen atoms stand for this adsorbent. A section of a cellulose chain is shown in Fig. 4. Fig. 4. Fragment of cellulose macromolecule Lab.2. Thin layer chromatography There are two kinds of cellulose layers used in TLC, native cellulose (400 -500 units per chain) and micro-crystalline cellulose that is prepared by the partial hydrolysis of regenerated cellulose and comprises between 40 and 200 units per chain. Similarly to the silica gel, cellulose surface can be modified by esterification (e.g. acetylation). Table.1. TLC stationary phases (adsorbents), mechanism of separation and examples of compounds separated with TLC Stationary Chromatographic Typical Application Phase Mechanism steroids, amino acids, alcohols, hydrocarbons, Silica Gel Adsorption lipids, aflaxtoxin, bile acids, vitamins, alkaloids fatty acids, vitamins, steroids, hormones, Silica Gel RP reversed phase carotenoids Cellulose, carbohydrates, sugars, alcohols, amino acids, partition kieselguhr carboxylic acids, fatty acids Aluminum amines, alcohols, steroids, lipids, aflatoxins, bile adsorption oxide acids, vitamins, alkaloids Solvents As it has been mentioned above, the choice of the mobile phase for chromatographic separation is dependent on interactions between mixture components in question with stationary phase. If polar interactions are involved in this process then solvents of dispersive character to molecular interaction (like hexane) in mixture with polar ones (e.g. ethyl acetate) are chosen as mobile phase solution. Analogously, if dispersive interactions predominate between adsorbent surface and solutes then solvents of polar properties (methanol or acetonitrile) in mixture with water are preferred. Lab.2. Thin layer chromatography The strength of solvent to elute solute molecules from the adsorbent surface (stationary phase) is characterized by polarity index (P’), which ranges from 0 (for non-polar solvent, e.g. pentane) to 10.2 (very polar one, water). When the mobile phase is a mixture of two solvents A and B then its polarity index, P’AB, is calculated according the following formula: ’ ’ ’ P AB = φAP A + φBP B (1) Where P’A and P’B are the polarity indexes of pure solvents A and B, respectively, and φA and φB are the molar fractions of A or B in the mobile phase, respectively. The polarity of a solvent can be evaluated by examining its dielectric constant (ε), dipole moment (δ) and ability to hydrogen bond formation. Table.2. Properties of solvents applied in liquid chromatography Solvent Dielectric Dipole Ability to Polarity Elution strength constant moment hydrogen (P’) Alumina Silica [D] bond formation hexene 1.88 0.00 not form 0.1 0.01 0.00 toluene 2.38 0.36 not form 2.4 0.29 0.22 chloroform 4.81 1.04 H-donor 4.1 0.40 0.26 dichloromethane 9.1 1.60 H-donor 3.1 0.42 0.30 tetrahydrofuran 7.5 1.75 H-acceptor 4.0 0.45 0.53 ethyl acetate 6.02 1.78 H-acceptor 4.4 0.58 0.48 acetone 21 2.88 H-acceptor 5.1 0.56 0.53 acetonitrile 37.5 3.92 H-acceptor 5.8 0.65 0.52 2-propanol 18 1.66 H-acceptor/ 3.9 0.82 0.60 H-donor ethanol 24.55 1.69 H-acceptor/ 8.8 0.88 0.69 H-donor methanol 33 1.70 H-acceptor/ 5.1 0.95 0.70 H-donor Source Wikipedia Lab.2. Thin layer chromatography Eluotropic series of solvents Solvents are arranged in a series according to increase of their elution strength in a chromatographic system with given stationary phase. Each adsorbent (stationary phase) possess its own eluotropic series of solvents. Mechanisms of chromatographic separation Several mechanisms are involved in solute separation in chromatographic system. The most often applied mechanisms of chromatographic separation are presented in Fig. 5. Fig. 5. The mechanisms of chromatographic solute separation often applied in laboratory practice Adsorption mechanism of chromatographic separation is very often used for solute separation. Migration of solute in chromatographic system in which adsorption mechanism is involved depends on: 1. molecular interactions of solute with stationary phase, 2. molecular interactions of solute with solvent (eluent,
Load more

Recommended publications
  • J . Org. Chem., Vol. 43, No. 14, 1978 2923 A
    Notes J. Org. Chem., Vol. 43, No. 14, 1978 2923 (11) Potassium ferricyanide has previously been used to convert vic-l,2-di- carboxylate groups to double bonds. See, for example, L. F. Fieser and M. J. Haddadin, J. Am. Chem. SOC., 86, 2392 (1964). The oxidative dide- carboxylation of 1,2dicarboxyiic acids is, of course, a well-known process. See inter alia (a) C. A. Grob, M. Ohta, and A. Weiss, Helv. Chirn. Acta, 41, 191 1 [ 1958); and (b) E. N. Cain, R. Vukov, and S. Masamune, J. Chern. SOC. D, 98 (1969). 1 I I L <40 26- 40- 63- 40 63 200 Rapid Chromatographic Technique for Preparative Figure 2. Silica gel particle size6 (pm):(0) rh: (0) r/(w/2). Separations with Moderate Resolution W. Clark Still,* Michael Kahn, and Abhijit Mitra Departm(7nt o/ Chemistry, Columbia Uniuersity, 1Veu York, Neu; York 10027 ReceiLied January 26, 1978 We wish to describe a simple absorption chromatography technique for the routine purification of organic compounds. 0 1.0 2 0 3.0 4.0 Large scale preparative separations are traditionally carried Figure 3. Eluant flow rate (in./min). out by tedious long column chromatography. Although the results are sometimes satisfactory, the technique is always time consuming and frequently gives poor recovery due to band tailing. These problems are especially acute when sam- ples of greater than 1 or 2 g must be separated. In recent years 41 several preparative systems have evolved which reduce sep- aration times to 1-3 h and allow the resolution of components having Al?f 1 0.05 on analytical TLC.
    [Show full text]
  • Synthesis and Applications of Monolithic HPLC Columns
    University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 8-2005 Synthesis and Applications of Monolithic HPLC Columns Chengdu Liang University of Tennessee - Knoxville Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Chemistry Commons Recommended Citation Liang, Chengdu, "Synthesis and Applications of Monolithic HPLC Columns. " PhD diss., University of Tennessee, 2005. https://trace.tennessee.edu/utk_graddiss/2233 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Chengdu Liang entitled "Synthesis and Applications of Monolithic HPLC Columns." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, with a major in Chemistry. Georges A Guiochon, Major Professor We have read this dissertation and recommend its acceptance: Sheng Dai, Craig E Barnes, Michael J Sepaniak, Bin Hu Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) To the Graduate Council: I am submitting herewith a dissertation written by Chengdu Liang entitled, “Synthesis and applications of monolithic HPLC columns.” I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, with a major in Chemistry.
    [Show full text]
  • Monolithic Stationary Phases for Capillary Electrochromatography Based on Synthetic Polymers: Designs and Applications Frantisek Svec, Eric C
    Reviews Monolithic Stationary Phases for Capillary Electrochromatography Based on Synthetic Polymers: Designs and Applications Frantisek Svec, Eric C. Peters1), David Sy´kora, Cong Yu, Jean M. J. Fre´chet* Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA Ms received: September 29, 1999; accepted: November 3, 1999 Key Words: Capillary electrochromatography; monolithic columns; synthetic polymers; stationary phase Summary Monolithic materials have quickly become a well-established station- the use of a solid stationary phase and a separation mechan- ary phase format in the field of capillary electrochromatography ism characteristic of HPLC based on specific interactions of (CEC). Both the simplicity of their in situ preparation method and solutes with a stationary phase. Therefore CEC is most com- the large variety of readily available chemistries make the monolithic monly implemented by means typical of both HPLC (packed separation media an attractive alternative to capillary columns packed with particulate materials. This review summarizes the con- columns) and HPCE (use of electrophoretic instrumentation). tributions of numerous groups working in this rapidly growing area, To date, both columns and instrumentation developed specifi- with a focus on monolithic capillary columns prepared from syn- cally for CEC remain scarce. thetic polymers. Various approaches employed for the preparation of the monoliths are detailed, and where available, the material proper- Although numerous groups around the world prepare CEC ties of the resulting monolithic capillary columns are shown. Their columns using a variety of approaches, the vast majority of chromatographic performance is demonstrated by numerous separa- these efforts mimic in one way or another standard HPLC tions of different analyte mixtures in variety of modes.
    [Show full text]
  • Identification Criteria for Qualitative Assays Incorporating Column Chromatography and Mass Spectrometry
    WADA Technical Document – TD2010IDCR Document Number: TD2010IDCR Version Number: 1.0 Written by: WADA Laboratory Committee Approved by: WADA Executive Committee Approval Date: 08 May, 2010 Effective Date: 01 September, 2010 IDENTIFICATION CRITERIA FOR QUALITATIVE ASSAYS INCORPORATING COLUMN CHROMATOGRAPHY AND MASS SPECTROMETRY The ability of a method to identify a compound is a function of the entire procedure: sample preparation; chromatographic separation; mass analysis; and data assessment. Any description of the method for purposes of documentation should include all parts of the method. The appropriate analytical characteristics shall be documented for a particular assay. The Laboratory shall establish criteria for identification of a compound. 1.0 Sample Preparation The purpose of the sample preparation and chromatographic separation is to present a relatively pure chemical component from the sample to the mass spectrometer. The sample purification step can significantly change both the performance of the chromatographic system and the mass spectrometer. For example, a change in extraction solvent can selectively remove interferences and matrix components that might otherwise co-elute with the compound of interest. In addition, selective preparation procedures such as immunoaffinity extraction or fractions collected from high performance liquid chromatography separation can provide a solution that is nearly devoid of any other compounds. 2.0 Chromatographic Separation 2.1 Gas Chromatography • For capillary gas chromatography, the retention time (RT) of the analyte shall not differ by more than two (2) percent or ±0.1 minutes (whichever is smaller) from that of the same substance in a spiked urine sample, Reference Collection sample, or Reference Material analyzed contemporaneously; • Alternatively, the laboratory may choose to use relative retention time (RRT) as an acceptance criterion, where the retention time of the peak of interest is measured relative to a chromatographic reference compound (CRC).
    [Show full text]
  • Column Chromatography Methods of Analysis In
    The Journal of Undergraduate Neuroscience Education (JUNE), Spring 2005, 3(2):A36-A41 ARTICLE Column Chromatography Analysis of Brain Tissue: An Advanced Laboratory Exercise for Neuroscience Majors William H. Church Chemistry Department and Neuroscience Program, Trinity College, Hartford, Connecticut 06106 Neurochemical analysis of discrete brain structures in to useful laboratory techniques such as standard solution experimental animals provides important information on preparation and calibration curve construction, centrifugation, synthesis, release, and metabolism changes following quantitative pipetting, and data evaluation and graphical behavioral or pharmacological experimental manipulations. presentation. Typically, only students that participate in Quantitation of neurotransmitters and their metabolites independent neuroscience research are familiar with these following unilateral drug injections can be carried out using types of quantitative skills. The usefulness of this type of standard chromatographic equipment typically found in most experimental design for understanding behavioral or undergraduate analytical laboratories. This article describes pharmacological effects on neurotransmitter systems is an experiment done in a six session (four hours each) emphasized through a final report requiring a comprehensive component of a neuroscience research methods course. The literature search. experiment provides advanced neuroscience students experience in brain structure dissection, sample preparation, and quantitation of catecholamines
    [Show full text]
  • Chapter 15 Liquid Chromatography
    Chapter 15 Liquid Chromatography Problem 15.1: Albuterol (a drug used to fight asthma) has a lipid:water KOW (see “Profile—Other Applications of Partition Coefficients”) value of 0.019. How many grams of albuterol would remain in the aqueous phase if 0.001 grams of albuterol initially in a 100 mL aqueous solution were allowed to come into equilibrium with 100 mL of octanol? C (aq) ⇌ C (org) Initial (g) 0.001 g 0 Change -y +y Equil 0.001-y y 푦 100 푚퐿 퐾푂푊 = 0.019 = (0.001−푦) ⁄100푚퐿 1.9 x 10-5 – 0.019y = y 1.019y = 1.9 x 10-5 y = 1.864x10-5 g albuterol would be in the octanol layer Problem 15.2: (a) Repeat Problem 15.1, but instead of extracting the albuterol with 100 mL of octanol, extract the albuterol solution five successive times with only 20 mL of octanol per extraction. After each step, use the albuterol remaining in the aqueous phase from the previous step as the starting quantity for the next step. (Note: the total volume of octanol is the same in both extractions). (b) Compare the final concentration of aqueous albuterol to that obtained in Problem 15.1. Discuss how the extraction results changed by conducting five smaller extractions instead of one large one. What is the downside to the multiple smaller volume method in this exercise compared to the single larger volume method in Problem 15.1? 푦 (a) Each step will have this general form of calculation: 퐾 = 20 푚퐿 푂푊 (푔푖푛푖푡−푦) ⁄100푚퐿 (퐾 )(푔 ) so we can calculate the g transferred to octanol from 푦 = 푂푊 푖푛푖푡 5+퐾푂푊 We can use a spreadsheet to calculate the successive steps: First extraction:
    [Show full text]
  • Recent Trends in the Application of Chromatographic Techniques in the Analysis of Luteolin and Its Derivatives
    biomolecules Review Recent Trends in the Application of Chromatographic Techniques in the Analysis of Luteolin and Its Derivatives Aleksandra Maria Juszczak 1 , Marijana Zovko-Konˇci´c 2 and Michał Tomczyk 1,* 1 Department of Pharmacognosy, Faculty of Pharmacy, Medical University of Białystok, ul. Mickiewicza 2a, 15-230 Białystok, Poland; [email protected] 2 Department of Pharmacognosy, University of Zagreb, Faculty of Pharmacy and Biochemistry, A. Kovaˇci´ca1, 10000 Zagreb, Croatia; [email protected] * Correspondence: [email protected]; Tel.: +48-85-748-5694 Received: 1 October 2019; Accepted: 8 November 2019; Published: 12 November 2019 Abstract: Luteolin is a flavonoid often found in various medicinal plants that exhibits multiple biological effects such as antioxidant, anti-inflammatory and immunomodulatory activity. Commercially available medicinal plants and their preparations containing luteolin are often used in the treatment of hypertension, inflammatory diseases, and even cancer. However, to establish the quality of such preparations, appropriate analytical methods should be used. Therefore, the present paper provides the first comprehensive review of the current analytical methods that were developed and validated for the quantitative determination of luteolin and its C- and O-derivatives including orientin, isoorientin, luteolin 7-O-glucoside and others. It provides a systematic overview of chromatographic analytical techniques including thin layer chromatography (TLC), high performance thin layer chromatography (HPTLC), liquid chromatography (LC), high performance liquid chromatography (HPLC), gas chromatography (GC) and counter-current chromatography (CCC), as well as the conditions used in the determination of luteolin and its derivatives in plant material. Keywords: luteolin; hyphenated techniques; chromatography 1. Introduction Luteolin (Figure1) is a yellow dye commonly found in fresh plants.
    [Show full text]
  • An Introduction to Chromatography
    Classification of Chromatographic Methods Classification of Chromatographic Methods (Geometry) •Planar –Paper – Thin layer • Column –GC –HPLC –IC – SFC Classification of Chromatographic Methods (Mobile Phase) • Gas Chromatography • Liquid Chromatography • Supercritical Fluid Chromatography Classification of Chromatographic Methods (Stationary Phase) • Adsorption • Partition • Ion-Exchange • Molecular Exclusion • Affinity Example of Affinity Chromatography Purification of monoclonal antibody on a 5 cm x 4.6 mm column with protein A covalently attached to a polymer support A Hot Idea: Molecular Imprinting An “artificial antibody” can be constructed by synthesizing a polymer in the presence of a template molecule. When the template is removed, the polymer is “imprinted” with the shape of the template and with complementary functional groups that can bind to the template. The imprinted polymer can be used as a stationary phase in affinity chromatography. Molecular Imprinting Hydrophobic Interaction Chromatography (HIC) • Based on the interaction of a hydrophobic stationary phase with a hydrophobic region of a solute such as a protein • A protein can have hydrophilic regions that make it soluble in water and hydrophobic regions interacting with a hydrophobic stationary phase • Proteins are adsorbed on the hydrophobic surface when the aqueous mobile phase contains high salt concentration • Eluent strength is increased by decreasing the salt concentration Hydrophilic Interaction Chromatography (HILIC) • Most useful for small molecules too polar to be retained by reversed-phase HPLC • Stationary phases are strongly polar • The mobile phase contains ≥ 80% polar organic solvent mixed with water Hydrophilic Interaction Chromatography (cont.) • Solute equilibrates between the mobile phase and a layer of aqueous phase on the surface of the stationary phase • Eluent strength is increased by increasing the fraction of water in the mobile phase.
    [Show full text]
  • 9.2.3.7 Retention Parameters in Column Chromatography
    9.2.3.7 Retention Parameters in Column Chromatography Retention parameters may be measured in terms of chart distances or times, as well as mobile phase volumes; e.g., tR' (time) is analogous to VR' (volume). If recorder speed is constant, the chart distances are directly proportional to the times; similarly if the flow rate is constant, the volumes are directly proportional to the times. Note: In gas chromatography, or in any chromatography where the mobile phase expands in the column, VM, VR and VR' represent volumes under column outlet pressure. If Fc, the carrier gas flow rate at the column outlet and corrected to column temperature (see Flow Rate), is used in calculating the retention volumes from the retention time values, these correspond to volumes at column temperatures. The various conditions under which retention volumes (times) are expressed are indicated by superscripts: thus, a prime ('; as in VR') refers to correction for the hold-up volume (and time) while a circle (º; as in VRº) refers to correction for mobile-phase compression. In the case of the net retention volume (time) both corrections should be applied: however, in order not to confuse the symbol by the use of a double superscript, a new symbol (VN, tN) is used for the net retention volume (time). Hold-up Volume (Time) (VM, tM ) The volume of the mobile phase (or the corresponding time) required to elute a component the concentration of which in the stationary phase is negligible compared to that in the mobile phase. In other words, this component is not retained at all by the stationary phase.
    [Show full text]
  • General Methods All Reactions Were Performed Under Nitrogen Atmosphere (Using Standard Schlenk Technique Or Glove Box)
    Supplementary Material (ESI) for Chemical Communications This journal is (c) The Royal Society of Chemistry 2010 Supporting information General methods All reactions were performed under nitrogen atmosphere (using standard Schlenk technique or glove box). All reagents were used as received unless otherwise stated. Tetrahydrofuran was distilled from benzophenone/sodium under nitrogen and stored over sodium in a glove box. Dissolving the substrate to be defluorinated in THF is not necessary. Same results are obtained when used neat. The dilute reaction mixtures described for the defluorination reactions originate from the use of stock solution used to facilitate the addition of the accurate amount of substrate. Column chromatography was performed using Silica Gel 60, 0.04–0.06 mm. 1H, 13C and 19F NMR spectra were recorded at a 400 MHz JEOL Eclipse 400 instrument, operating at 400 MHz for 1H nuclei. An 800 MHz Varian instrument was used as complement for menthyl-2,3,3,3-tetrafluoropropanoate. Samples were dissolved in CDCl3 and chemical shifts are given in ppm (parts per million) relative to residual CHCl3 (7.26 ppm), α,α,α- trifluorotoluene (-63.6 ppm) was used as internal standard for 19F NMR. Gas chromatography/mass spectrometry analyses were performed on a DB-5 equivalent capillary column (length 30m, i.d. 25 μm) using helium as carrier gas. Injector temperature 300 °C. Temperature program: 40 to 330 °C (12 °C/min) with 4 minutes hold time. The MS detector consisted of an ion trap with 70 eV ionization. Preparation of SmI2 in THF Diiodoethane (23 mmol, 6.58 g) was added to dry THF (194 ml).
    [Show full text]
  • The LC Handbook Guide to LC Columns and Method Development Contents
    Agilent CrossLab combines the innovative laboratory services, software, and consumables competencies of Agilent Technologies and provides a direct connection to a global team of scientific and technical experts who deliver vital, actionable insights at every level of the lab environment. Our insights maximize performance, reduce complexity, and drive improved economic, operational, and scientific outcomes. Only Agilent CrossLab offers the unique combination of innovative products and comprehensive solutions to generate immediate results and lasting impact. We partner with our customers to create new opportunities across the lab, around the world, and every step of the way. More information at www.agilent.de/crosslab Learn more The LC Handbook – Guide to LC Columns and Method Development www.agilent.com/chem/lccolumns Buy online www.agilent.com/chem/store Find an Agilent customer center or authorized distributor www.agilent.com/chem/contactus U.S. and Canada 1-800-227-9770 [email protected] Europe [email protected] Asia Pacific [email protected] The LC India [email protected] Handbook Information, descriptions and specifications in this publication are subject to change without notice. Agilent Technologies shall not Guide to LC Columns and be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing, performance or use of this material. Method Development © Agilent Technologies, Inc. 2016 Published in USA, February 1, 2016 Publication Number 5990-7595EN
    [Show full text]
  • Quantitative Thin-Layer Chromatography
    Quantitative Thin-Layer Chromatography A Practical Survey Bearbeitet von Bernd Spangenberg, Colin F. Poole, Christel Weins 1. Auflage 2011. Buch. xv, 388 S. Hardcover ISBN 978 3 642 10727 6 Format (B x L): 15,5 x 23,5 cm Gewicht: 839 g Weitere Fachgebiete > Chemie, Biowissenschaften, Agrarwissenschaften > Analytische Chemie > Instrumentelle Chemische Analytik, Chromatographie Zu Inhaltsverzeichnis schnell und portofrei erhältlich bei Die Online-Fachbuchhandlung beck-shop.de ist spezialisiert auf Fachbücher, insbesondere Recht, Steuern und Wirtschaft. Im Sortiment finden Sie alle Medien (Bücher, Zeitschriften, CDs, eBooks, etc.) aller Verlage. Ergänzt wird das Programm durch Services wie Neuerscheinungsdienst oder Zusammenstellungen von Büchern zu Sonderpreisen. Der Shop führt mehr als 8 Millionen Produkte. Chapter 2 Theoretical Basis of Thin Layer Chromatography (TLC) 2.1 Planar and Column Chromatography In column chromatography a defined sample amount is injected into a flowing mobile phase. The mix of sample and mobile phase then migrates through the column. If the separation conditions are arranged such that the migration rate of the sample components is different then a separation is obtained. Often a target compound (analyte) has to be separated from all other compounds present in the sample, in which case it is merely sufficient to choose conditions where the analyte migration rate is different from all other compounds. In a properly selected system, all the compounds will leave the column one after the other and then move through the detector. Their signals, therefore, are registered in sequential order as a chromatogram. Column chromatographic methods always work in sequence. When the sample is injected, chromatographic separation occurs and is measured.
    [Show full text]