introducción al análisis cromatográfico · definiciones gases: gas de transporte (carrier) –...

Introducción al AnálisisCromatográfico

19/10/2012 Detectores

Criterios Básicos

Diseño de un Sistema de Cromatografía de Gases


Diagrama de bloques de un Cromatografo

TemperatureControl

QualitativeAnalysis

Gases SampleIntroduction

Column Detector

Electronics

OutputDevice

QuantitativeAnalysis


Cromatografo de Gases Típico

Column

FlowController

Regulators

Air

Hyd

roge

n

Car

rier G

as

Mol-SieveTraps

Fixed

InjectionPort Detector Electrometer

Recorder/Integrator

Restrictors


DefinicionesGases:

◦ Gas de Transporte (carrier) – Fluido que transporta la muestraa través del sistema cromatográfico

◦ Gases del Detector – Gases adicionales que puede requerir un detector para su adecuado funcionamiento (Ejemplo el FID queusa Hidrógeno y aire sintético)

Introducción de la muestra: INYECTOR:◦ Introduce la muestra en la corriente de flujo del gas de

transporte en forma segura y reproducible.Columna:

◦ Es donde se produce la separación de los componentes de la muestra.

Detector:◦ Reconoce y genera una respuesta a la salida de los

compuestos de la columnaAdquisición de datos:

◦ Convierte la señal del detector en el registro denominadoCROMATOGRAMA.


Qué es un cromatograma?

.

30 M x 0.32 mm x 0.25 uM HP5Capillary Column Analysis:

Column Flowrate = 1 mL/minLinear Velocity = 20.5 cm/sec

Temperature Program:Isothermal 160

FID

1 uL Column Checkout sample

Split Mode:Split Ratio = 100:1

Area Percent ReportPk# Ret. Time Area Height Type Width Area% Name1 2.442 62321 45133 BV 0.022 0.2127 Pentane2 2.556 2.9045E+07 1.87002E+07 VV 0.024 99.11066 Solvent3 2.672 8303 5036 VB 0.026 0.0283+4 3.100 10129 7143 BB 0.023 0.0346 Undecane5 3.511 14978 7438 BB 0.032 0.0511 4-Chlorophenol6 3.816 16871 9417 BB 0.028 0.0576 1-Decylamine7 4.156 17124 9425 BB 0.029 0.0584 Tridecane8 4.359 7748 3907 BB 0.031 0.0264 Methyl caprate9 5.179 33486 14578 BB 0.046 0.1143 Tetradecane10 6.315 27045 9249 BB 0.046 0.0923 Acenaphthylene11 6.542 29540 8682 BB 0.053 0.1008 1-Dodecanol12 6.789 34293 11407 BB 0.047 0.1170 PentadecaneTotal area = 2.9307E +07

1 2

3

45

6 7

8

9 10 11 12


Que debo hacer para efectuar un análisis porcromatografía de gases


Split Injection

FLOWSENSOR

PROPORTIONALVALVE 1

PRESSURESENSOR

SEPTUM PURGEREGULATOR

FIXED @ 3ML/MIN

PURGEVALVEOPEN

TOTAL FLOWCONTROL LOOP

INPUTPRESSURE

PROPORTIONALVALVE 2

80 PSI205

ML/MIN

SPLIT VENTTRAP

10

PSI

SPLIT

VENT

200 ML/MIN

COLUMN FLOW

2 ML/MIN

BACK PRESSURE CONTROL LOOP

Split Ratio - 100:1


¿Cuando usamos un inyector split/splitless?

Para uso general, se recomienda la inyección split

• Petroleo / petroquímica• Química • Alimentos / sabores / Fragancias

La inyección splitless se usa en el análisis de trazas

• Medio Ambiente• Traza de impurezas en cualquier compuesto


Detectors

Thermal Conductivity Detector (TCD)

Flame Ionization Detector (FID)

Micro Electron Capture Detector (µECD)

Nitrogen Phosphorus Detector (NPD)

Flame Photometric Detector (FPD)

Mass Selective Detector (MSD)

Atomic Emission Detector (AED) ( just been obs.)


in the carrier gas pass over it, causing the resistance

As electronegative species pass through the detector,they capture low energy thermal electrons causing a

Filament temperature increases as the analytes

to increase.

TCD

FID

ECD

Components burn in a flame producing ions whichare collected and converted into a current.

decrease in cell current.

NPD

FPD

Nitrogen and phosphorous compounds produceincreased currents in a flame enriched with vaporizedalkali metal salt.

Sulphur and phosphorous compounds burn in aflame producing chemiluminescent species which are monitored at selected wave lengths.

MSD

AED

Molecules are bombarded with electrons producingion fragments which pass into the spectrometer'smass filter. The ions are filtered based on theirmass/charge ratio.

Molecules are energized by a plasma source andseparated into excited atoms. As electrons return totheir stable state, they emit element specific light.

How Detectors Work


Typical Detector Operating Ranges

TCD

FID

ECD

AED

N-P (N)

FPD (S)

SCD (S)

PFPD (S)

N-P (P)

10 -15 10 -12 10 -9 10 -6 10

fg pg ng µg mg

-3

MSD (SIM) (SCAN)

µECD

FPD (P)

ppt ppb ppm 0.1%

HID


Type

FID

TCD

µ-ECD

NPD

FPD

FPD

Hydrocarbons

General

Organohalogens

Organonitrogen

Sulfur compounds

Phosphorus

SensitivityRange

10-100 pg

5-100 ng

0.008-4000 pg

0.1-10 pg

10-100 pg

1-10 pg

Carrier +Makeup

20-60

15-30

30-60

20-40

20-40

20-40

HTypicalSamples 2

Chlorinated solvents& pesticides

10 ppm-100%

10 ppb-99%

Air

30-40 200-500

n.a. n.a.

8 ppt - 1%n.a. n.a.

& organophosphoruscompounds

100 ppt-0.1%1-5 70-100

(393 nm) 10 ppb-100 ppm50-70 60-80

(526 nm) compounds 1 ppb-0.1%120-170 100-150

PID

ELCD

AED

Compounds ionizedby UVHalogens, N, S

Tunable to element

2pg C/sec

0.5 pg Cl/sec2 pg S/sec4 pg N/sec0.1 - 20 pg/sec

n.a.

n.a.

30-40

20-40

60-70

*

80

PRESET PRESET

General Information on Detectors


Sensitivity:

Selectivity:

Dynamic Range:

The response per amount of sample, that is,

the slope of the response/amount curve. The

minimum amount on the curve is defined as the

A measure of which categories of compounds

will give a detector response.

The range of sample concentrations for which

the detector can provide accurate quantitation.

minimum detectable level (MDL).

Definitions

Quantity

Res

pons

e


Capillary Columns and Detector Selectivity

FID ECD NPD (P)


The FID is a

destructive, mass

sensing detector.

Cations generated

in the flame are

counted and produce

the detector signal.

Analytes that have

the greatest number

of low oxidation state

carbons produce the

largest signal.

Column

Jet

H2

H2

H2

H2

H2

H2

CH 4

CH 4

CH 4

CH 4

CH 4

CH 4

CHO+

CHO+

CHO+

CHO+

CHO +CO2

CO2CO2

H 02

H 02

H 02

H2

H2

H2

H2

H2

H2

H 02

Flame Ionization Mechanism


Substances with Little or No Response in FID

Rare gases

Nitrogen oxides

Silicon halides

H O

Perhalogenated cpds2

NH

H

CO

CO

HCOH

2

2

3 CS

COS

O

N

HCO H

2

2

22


Exit end of column

Jet

Air in

H2 + make-up in

FID DetectorAssembly

Capillary Column end-Position(1-2 mm from top of Jet)

Detector de Ionización de Llama (FID)

Respuesta a todo tipo de compuesto orgánico

El Detector más popular


Aplicaciones típicas para el FID

Pharmaceutical Application◦ USP 467 Analysis

Foods & Flavors Application◦ Fatty Acid Methyl Esters

(FAME)◦ Wine, Fragrance...

Environmental Application◦ Polunuclear Aromatic

Hydrocarbons (PAH

Hydrocarbon Process Application

◦ Gasoline, Kerosene ...◦ Impurity in Solvents◦ SIMDIS

Chemical/Industrial Application

◦ Aromatics◦ Alcohol


TCD Mechanism

FLOW

The TCD is a non destructiveconcentration detector. Aheated filament is cooled bythe flow of pure carrier gas

When the carrier is contaminated by sample components the filament looses less heat and becomes hotter. This change is used to generate the signal.


Typical Applications for TCD

Noble/Permanent Gases Neon, Argon...

Hydrocarbon Process Gases Natural Gas Analysis Refinery Gas Analysis


Example Application of TCD

Retention Time in Second

20 30 40 50 60 70 80 90 100 110 120 130

2

1

3

4

6

5 1. He2. H23. O24. N25. Methane6. CO


6890 Plus Micro-ECD

Standard1.5 mL

Anode

Capillary Column

Fused Silica Insert

Detection Zone

Anode

Detection Zone

Micro 150 mcL


Micro-ECD Specifications

Dynamic Range: >5 x 10^5(0.008 to 4000 pg lindane)

Linearity: >5 x 10^4(0.04 - 2000 pg lindane)

Exceeds CLP linearity requirements for all listed pesticides and surrogates from

1 to 500 pg/ul


Typical Applications for Micro-ECD

Environmental– Pesticides and PCB's analysis– Phthalates, nitro-compounds, volatile Cl compounds

Flavors & Fragrances, Consumer, Pharmaceutical– Trace residual solvent analysis– Derivatized compounds


Example Application of ECD: Tap Water Analysis

1 2 3 4 5 6 7

1

2

3

4

1 Chloroform 23 ppb 2 Bromodichloromethane 18 ppb3 Chlorodibromomethane 8 ppb4 Bromoform 3.4 ppb


Flame Photometric Detector

Sulfur and Phosphorus containing compounds produce chemiluminescent species when burned in an FID-type flame.

An optical filter permits light of the specific wavelength to enter the photomultiplier to produce a signal.

Interference filter:526 nm for P393 nm for S


Flame Photometric Detector19/10/2012 Detectores

Typical Applications for FPD

Hydrocarbon Process Application Sulfur in gasoline Sulfur in natural gas

Chemical/Industrial Application Sulfur impurity in PGE, PGP

Environmental Application Pesticides analysis

Flavors & Fragrances Beverages - sulfur containing compounds


Example Application of FPD:

20-40 ppb organophosphate pesticides

1-2 ppm organophosphate pesticides

Compounds:l phoratel demetonl disulfotonl diazinonl malathionl fenthionl parathionl trichloronatel tokuthionl fensulfothionl ethionl sulprofosl guthionl coumaphos


Example Application of FID:

Unified Aromatics MethodSeparates 27 compounds found in aromatic solvents

5 10 15 20

1 2 3

4 5

6

7 8 9 10 11 12 13 1415 16 1718

1920

2122

23

24

25 26

27

1 heptane 8 ethylbenzene 15 m-ethyltoluene 22 diethylbenzene isomer2 cyclohexane 9 p-xylene 16 t-butylbenzene* 23 diethylbenzene isomer3 nonane 10 m-xylene 17 s-butylbenzene 24 n-butylbenzene4 benzene 11 cumene 18 styrene 25 a-methylstyrene5 toluene 12 o-xylene 19 tridecane 26 phenylacetylene6 1,4-dioxane 13 propylbenzene 20 psuedocumene 27 durene7 undecane 14 p-ethyltoluene 21 cyclohexanone


Chemistry and Materials ScienceChromatographiaVolume 34, Numbers 5-8, 219-225, DOI: 10.1007/BF02268349 Pulsed discharge helium ionization detector W. E. Wentworth, S. V. Vasnin, S. D. Stearns and C. J. Meyer


introducción al análisis cromatográfico · definiciones gases: gas de transporte (carrier) –...

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