Chemkeys English » Chromatography http://chemkeys.com/en freedom to learn Sun, 17 Apr 2011 23:57:20 +0000 en hourly 1 Supercritical Fluid Extraction http://chemkeys.com/en/2006/04/17/supercritical-fluid-extraction/ http://chemkeys.com/en/2006/04/17/supercritical-fluid-extraction/#comments Mon, 17 Apr 2006 20:35:44 +0000 Alessandra Franchi http://eccen.net/chemkeys3/chemkeysen/?p=192 Abstract

This work presents a discussion about the characteristics of supercritical fluid extraction, its operational conditions, a comparison with other extraction techniques and analytical applications of this technique. The text shows that a supercritical fluid can be obtained with different substances if they are above their critical point, the critical temperature and critical pressure, which can be viewed as a phase diagram. Among the most used supercritical fluids is carbon dioxide due to its low critical parameters, and because it is not toxic, not flammable and inert. Also, in addition to being gaseous at room temperature, it is highly accessible, easily obtainable with a high degree of purity at low cost and it can still be modified by the addition of organic solvents. The extraction operation with a supercritical fluid also permits on-line couplings and the recovery of the solvent used. The parameters governing SFE are discussed, particularly pressure, temperature, the nature of the matrix and the polarity of the extractor fluid. Some points of comparison show that extraction with a supercritical fluid is an attractive technique to be applied in the preparation of solid samples, since it has advantages compared to other alternative sample preparation techniques (Soxhlet, ultrasound, accelerated solvent extraction, among others). Among those are the speed of the extraction process, its low cost per extraction, the reduced consumption of organic solvents, fewer handling procedures, good precision and accuracy, versatility, good recovery and ease of automation. This text also presents some applications of SFE, which are many and varied, including environmental samples (soil, water, air, sediment and suspensions), food (fruits, vegetables, cereals, animal tissues, etc), natural products (essential oils, flavorings, etc), drugs (drugs of abuse, hormones, etc) and polymers.

Keywords
extraction, supercritical fluid, Analytical Chemistry, fluid extractor, chromatography

Autores
Glaucia M. F. Pinto
Pontifícia Universidade Católica de Campinas, Faculdade de Química
Jefferson F. Pinto
Protimu Ltda
Isabel C. S. F. Jardim
Universidade Estadual de Campinas, Instituto de Química

Translated by
João C. de Andrade

Revised by
Carol H. Collins

]]> http://chemkeys.com/en/2006/04/17/supercritical-fluid-extraction/feed/ 0 Quantitative Analysis by Chromatography http://chemkeys.com/en/2003/10/01/quantitative-analysis-by-chromatography/ http://chemkeys.com/en/2003/10/01/quantitative-analysis-by-chromatography/#comments Wed, 01 Oct 2003 13:32:06 +0000 Alessandra Franchi http://eccen.net/chemkeys3/chemkeysen/?p=50 Abstract

This is a support text to the Quantitative Analysis by Chromatography multimedia application available in Applications and Programs. As its purpose is to provide the same material in printed form to the reader, this text is more detailed than that presented in the application, although with a smaller number of figures. It is also an alternative way to present the information, serving either as a supporting material or as a resume of to the original multimedia application.

Keywords
chromatography, calibration curve, data processing, mean, median, confidence intervals, rejection of data, Huber test, internal standard, external standard

Authors
Antônio Luiz Pires Valente (in memoriam)
Cássio Ricardo Fares Riedo
Fabio Augusto
Universidade Estadual de Campinas, Instituto de Química

Translated by
João C. de Andrade

Revised by
Carol C. Collins

]]> http://chemkeys.com/en/2003/10/01/quantitative-analysis-by-chromatography/feed/ 0 Gas Chromatography: A Course in Slides http://chemkeys.com/en/2000/07/01/gas-chromatography-a-course-in-slides/ http://chemkeys.com/en/2000/07/01/gas-chromatography-a-course-in-slides/#comments Sat, 01 Jul 2000 17:59:05 +0000 Alessandra Franchi http://eccen.net/chemkeys3/chemkeysen/?p=79 Abstract

The separation and analysis of a mixture of volatile substances can be made through Gas Chromatography (GC). The use of this technique requires some care, among them the choice of correct stationary phase (SP) and mobile phase (MP). The temperature must be controlled, to secure the reproducibility of the analysis. These and other critical points of the Gas Chromatographic technique will be addressed in this article.

Keywords
Chromatography, Gas Chromatography, Chromatography column, Tubular columns, Packed column, Sationary phase, Detectors.

Author
Fábio Augusto
Universidade Estadual de Campinas, Instituto de Química

Download Files

This text about gas chromatography is accompanied by a group of 120 slides (transparences; in portuguese), which illustrate the material and add elements that must be considered by the reader for future use and study. This slideshow is compressed into 21 files and, to utilize them, they must be:

1. Saved in a directory in your computer;;
2. Unpacked utilizing an appropriate program, and
3. Open the files in the PowerPoint program (part of the Microsoft Office packed) or your equivalent in StarOffice pack, available in [www.sun.com/staroffice].

Each pack of file [zipped] contains from 4 to 7 slides and are presented below.

Files

Table 1. Content of file to download.

CG01

1. History

2. Basic Principle

3. Modalities and Classification

4. Gas Chromatography: History

5. Gas Chromatography: Applicability

6. The Gas Chromatograph

CG02

1. Instrumentation: Carrier gas

2. Instrumentation: Carrier gas

3. Instrumentation: Carrier gas feed

4. Instrumentation: Sample injection device

5. Instrumentation: Conventional injector “on-column”

6. Instrumentation: Injector “on-column” for liquids

CG03

1. Instrumentation: Injection parameters

2. Instrumentation: Microsyringes for injection

3. Instrumentation: Columns: basics definitions

4. Instrumentation: Column temperature

5. Instrumentation: Column temperature

6. Instrumentation: Column furnace

7. Instrumentation: Column furnace

CG04

1. Instrumentation: Linear temperature programming

2. Instrumentation: Linear temperature programming

3. Instrumentation: Linear temperature programming

4. Instrumentation: Detectors

5. Instrumentation: Detectors

CG05

1. Basic Theory: Adjusted Retention Time, tR‘

2. Basic Theory: Adjusted Retention Volume, VR‘

3. Basic Theory: Distribution Constant, Kc

4. Basic Theory: Retention Factor, k

5. Basic Theory: Phase Ratio,  β

6. Basic Theory: Relation between VR‘, KC‘ and β

CG06

1. Basic Theory: Chromatographic system efficiency

2. Basic Theory: Quantification of Efficiency

3. Basic Theory: Quantification of Efficiency

4. Basic Theory: Optimization of efficiency

5. Stationary Phases: General concepts

CG07

1. Stationary Phases: Characteristics of ideal SP

2. Stationary Phases: Characteristics of ideal SP

3. Stationary Phases: Solid SP: Adsorption

4. Stationary Phases: Solid SP

5. Stationary Phases: Liquid SP: Absorption

CG08

1. Stationary Phases: Liquid SP families

2. Stationary Phases: Liquid SP families

3. Stationary Phases: Liquid SP families

4. Stationary Phases: Liquid SP families

5. Stationary Phases: Liquid SP families

6. Stationary Phases: Liquid SP families

7. Stationary Phases: Liquid SP families

CG09

1. Stationary Phases: Chiral SP

2. Stationary Phases: Chiral SP

3. Stationary Phases: Chiral SP

4. Stationary Phases: Chiral SP: applications

5. Stationary Phases: Chiral SP: applications

6. Stationary Phases: Chiral SP: applications

CG10

1. Packed Columns: Basic Definitions

2. Packed Columns: Liquid SP: Support

3. Packed Columns: Liquid SP: Support

4. Packed Columns: Liquid SP: SP loading

CG11

1. Capillary Columns: Basic Definitions

2. Capillary Columns: Inner Diameter

3. Capillary Columns: “Fast GC”: narrow capillary Columns

4. Capillary Columns: Capillaries Columns: injection

5. Capillary Columns: Large Volume Injection (LVI)

6. Capillary Columns: Large Volume Injection (LVI)

7. Capillary Columns: Many-capillary Columns

CG12

1. Detectors: General Definitions

2. Detectors: Basic Parameters of Performance

3. Detectors: Basic Parameters of Performance

4. Detectors: Basic Parameters of Performance

5. Detectors: Basic Parameters of Performance

6. Detectors: Basic Parameters of Performance

CG13

1. Detectors: Classification

2. Detectors: Thermal Conductivity Detector

3. Detectors: Thermal Conductivity Detector

4. Detectors: Thermal Conductivity Detector

CG14

1. Detectors: Operational Characteristics of TCD

2. Detectors: Operational Characteristics of TCD

3. Detectors: Operational Characteristics of TCD

4. Detectors: Operational Characteristics of TCD

5. Detectors: TCD: Applications

CG15

1. Detectors: Flame Ionization Detector

2. Detectors: Flame Ionization Detector

3. Detectors: Flame Ionization Detector

4. Detectors: Operational Characteristics of FID

5. Detectors: Operational Characteristics of FID

6. Detectors: Operational Characteristics of FID

7. Detectors: Operational Characteristics of FID

CG16

1. Detectors: Nitrogen-Phosphorus Detector

2. Detectors: Electron Capture Detector

3. Detectors: Electron Capture Detector

4. Detectors: Electron Capture Detector

CG17

1. Detectors: Operational Characteristics of ECD

2. Detectors: Operational Characteristics of ECD

3. Detectors: Operational Characteristics of ECD

4. Detectors: Operational Characteristics of ECD

5. Detectors: Operational Characteristics of ECD

6. Detectors: ECD: Applications

CG18

1. Qualitative Analysis: General Concepts

2. Qualitative Analysis: Retention Times

3. Qualitative Analysis: Retention Times

4. Qualitative Analysis: Retention Times

5. Qualitative Analysis: Kovats Retention index

6. Qualitative Analysis: Kovats Retention index

7. Qualitative Analysis: Kovats Retention index

CG19

1. Qualitative Analysis: Retention Time Locking (RTL)

2. Qualitative Analysis: Qualitative Detection Methods

3. Qualitative Analysis: Mass Spectrometry

4. Qualitative Analysis: Mass Spectrometry

5. Qualitative Analysis: Mass Spectrometer

CG20

1. Qualitative Analysis: Coupling GC-MS

2. Qualitative Analysis: Coupling GC-MS

3. Qualitative Analysis:GC-MS: Chromatogram Generation

4. Qualitative Analysis: Coupling GC-MS: TIC x SIM

5. Qualitative Analysis: Eluate Identification

6. Qualitative Analysis: Eluate Identification

CG21

1. Qualitative Analysis: Plasma Atomic Emission

2. Qualitative Analysis: Plasma Generation and Sustentation

3. Qualitative Analysis: Optical Emission Spectra

4. Qualitative Analysis: Typical Scheme of a GC-OED

5. Qualitative Analysis: OED: Plasma Generation

6. Qualitative Analysis: GC-OED interface


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