Có 80+ tài liệu thuộc chủ đề "sắc ký lỏng HPLC"
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Each subsection should include a brief summary of the applicable protocol, and the mean, standard deviation, relative standard deviation, acceptance criteria, and assessment (pass or fail).. A properly designed validation protocol can serve as a template for the validation report. For example, in the protocol a test can be described and the acceptance criteria listed. For the validation report, this...
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12.7.1.2 Co-validation between Laboratories. Comparative testing (Section 12.7.1.1) traditionally requires a validated method as a prerequisite to AMT. However, another option for AMT is to involve the receiving laboratory from the beginning in the actual validation of the test method to be transferred. 12.7.1.3 Method Validation and/or Revalidation. Another technique that can be used for AMT involves the receiving laboratory’s...
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Guideline for Submitting Samples and Analytical Data for Methods Validation, USFDA-CDER (February 1987), http://www.fda.gov/cder/guidance/ameth.htm.. 2000), http://www.fda.gov/cder/guidance/2396dft.htm.. 2005), http://www.ich.org/LOB/media/MEDIA417.pdf.. Guidance for Methods Development and Methods Validation for the Resource Con- servation and Recovery Act (RCRA) Program, US EPA, (1995), http://www.epa.gov/. ISO/IEC 17025, General Requirements for the Competence of Testing and Calibration Laboratories, (2005), http://www.iso.org/iso/iso catalogue/catalogue tc/. Current Good Manufacturing Practice in...
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Figure 13.4 Schematic diagram of the helical structure of DNA, showing hydrogen bonding between complementary base pairs.. Exposure of the helix to elevated temperature or extremes of pH can induce separation of the two strands.. these structures can be dissociated by heat or chemically denaturing conditions.. 13.2.3 Carbohydrates. 13.5) are glucose, galactose, mannose, fucose, N-acetylgalactosamine (GalNAc), and N-acetylglucosamine (GlcNAc). Figure...
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The hydrophobicity (and therefore retention) of a polypeptide is heavily dependent on the ionization state of the amino-acid termini (approximate pK a values of 2.4 and 9.8) and of the ionizable side chains of internal residues (pK a values in Fig. Thus the pH of the mobile phase can have a profound effect on polypeptide retention, and it is necessary...
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other column lengths, diameters and par- ticle sizes can be used, in which case gradient time and flow rate should be adjusted to maintain similar values of k ∗ with acceptable pressure drop. b Higher temperatures (e.g C) can be desirable for some protein samples, especially those with M >. Figure 13.10, the initial four runs a –d can be...
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Figure 13.19 Steps in the use of IMAC. Adapted from [56].. amino-acid side chains in the protein can form coordination complexes with metals, so IMAC is a general method for protein separation. the strength of metal binding by different amino-acid groups in the protein molecule decreases in the following order:. Cysteine residues can bind metals, but they may not be...
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anion-exchange conditions, the negative charge of a single phosphate group is insufficient to counteract the electrostatic repulsion of N-terminal and side-chain amines, and monophosphorylated peptides elute in or near the void volume. When a weak anion exchange column is operated in the ERLIC mode with higher %-ACN, hydrophilic interaction drives an increased interaction of phosphates, enabling the retention and resolution...
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Figure 13.34 Isocratic HILIC separations of a homologous mixture of. 13.6.2 Ion-Moderated Partition Chromatography. Resins with a low percentage of cross-linking are preferred, in order to allow penetration of the oligosaccharides into the packing. Figure 13.35 shows the separation of oligosaccharides in a corn syrup. For monosaccharides, ligand exchange of the sugar hydroxyls with the fixed counter-ion on the resin...
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The porosity of an SEC column can be characterized by its phase ratio (V i /V 0. as in Figure 13.39a. As particle pore-diameter and pore-volume increase, the mechanical strength of the support decreases.. 13.8.2.3 Particle Diameter. Column packings with particle diameters of 10 to 12 μm are available for less demanding applications, such as preparative separations, while SEC packings...
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Figure 13.45 Preparative separation of rh-insulin. and 4.4–5.4 C-Vs plus recovered solvent from column regeneration) contained an additional 15% of the product (for re-separation)—for an overall insulin recovery of 97%. The initial purity of the sample for RPC separation was 91.5%. 13.9.2.9 Scale-Up. Scale-up experiments were carried out next, using six, successively larger, axial-compression columns, with the bed-volume increased from...
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13.10.3.5 Chemical Composition as a Function of Molecular Size. A copolymer typically exhibits both molecular-weight and chemical-composition distributions. Depending on polymerization conditions, the chemical composition may or may not vary with polymer molecular weight. To investigate the presence of such chemical heterogeneity, we can couple SEC with a spectroscopic technique that yields chemical-composition information. Although information about chemical composition as...
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14.7.2 Thermodynamics of Direct Chromatographic Enantiomer Separation, 716. 14.7.3 Site-Selective Thermodynamics, 717. 14.1 INTRODUCTION. that is, separations that can be used for many different kinds of samples. Usually method development can be started with any of various columns or conditions, and resolution is then systematically improved by varying separation conditions. Furthermore, in most cases, the selection of the column is...
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Mobile phase. Figure 14.8 Equilibria for the retention of R- and S- enantiomers (chiral–mobile-phase addi- tive, CMPA) mode. distribution of the complexed solutes X. X can complex directly with the CMPA in the stationary phase (via processes i and j in Fig. The same equilibria have to be considered for the S-enantiomer (S)-X. The consequences of Figure 14.8 can be...
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If the mobile phase is changed, sufficient equilibration time should be allowed to ensure the complete removal of the polar solvent. In order to achieve reproducible results, when switching from an additive-free to an additive-containing mobile phase (e.g., 0.1% trifluoroacetic acid or diethylamine), and vice versa, a prolonged equilibration time may be required [55].. In rare cases the use of...
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Figure 14.16 Separation of propranolol enantiomers on a protein column (cellobiohydro- lase I. extreme conditions, can easily lead to chemical or biochemical changes of the protein selectors. Another disturbing limitation is a low to moderate column efficiency, as seen in the example separation of Figure 14.16 (N = 300–700). 14.16), low plate numbers, combined with peak tailing, can make the...
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14.6.6 Chiral Crown-Ether CSPs. Stereoselective CSP-analyte complexation with chiral crown-ether CSPs and their first application as CSPs were pioneered by Cram and coworkers [127]. In this early work, two 1,1 -binaphthyl units were incorporated into a crown ether as replacement elements of two ethylene groups of the well-known 18-crown-6.. Structural analogues of such 1,1 -binaphthyl-derived chiral crown-ether based CSPs were...
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Further manipulation of Equation (14.3) provides two additional relationships:. K i,S = −R · T · ln α (14.5) That is, plots of ln K i against 1/T are predicted to be linear, with a slope that is proportional to H 0 i . 14.7.2 Thermodynamics of Direct Chromatographic Enantiomer Separation If a single type of (enantioselective) solute-selector interaction is...
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15.1 INTRODUCTION. A closely allied separation technique, supercritical fluid chromatography [1], is beyond the scope of the present chapter.. 15.1.1 Column Overload and Its Consequences. Prep-LC involves mass-overload conditions, that is, sample weights that are large enough to affect peak widths and retention times. When developing an analytical separation, care is usually taken to ensure that the weight (or volume)...
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this can lead to degradation of the product. NPC is also often favored by a potentially larger value of the separation factor α, which corresponds to larger allowable sample weights (as in the example of Figure 15.2. RPC is not ruled out for prep-LC separation, as there are several options for the recovery of solvent-free product—depending on the nature of...