INDICATORS
NITROGEN PHOSPHORUS DETECTOR(NPD
ELECTRON CAPTURE DETECTOR(ECD)
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PRINT LAYOUT
1.
INTRODUCTION
2.
DIAGRAM FOR NPD
3.
WORKING PRINCIPLES FOR NPD
4.
ADVANTAGES OF NPD
5.
DISADVANTAGES OF NPD
6.
STRUCTURE OF ECD
7.
WORKING PRINCIPLES OF ECD
8.
ADVANTAGES OF ECD
9.
DISADVANTAGES OF ECD
10.
COMPARE AND CONTRAST THE PRINPLES OF ECD AND NPD
11.
COMPARE AND CONTRAST THE INSTRUMENTATION OF NPD AND ECD
12.
CONCLUSSION
13.
REFFERENCES
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INTRODUCTION

DETECTORS ARE DEVICES USED TO OR DESIGNED TO RESPOND TO A VERY SMALL
QUANTITY OF SAMPLE PRESENT IN THE COLUMN GAS.THERE ARE A VARIETY OF
INDICATORS IN THEIR VARIOUS TYPES HOWEVER IN THIS SLIDE WE WILL FOCUS
MAINLY ON NITROGEN PHOSPHORUS DETECTOR AND ELECTRONIC CAPTURE
DETECTOR .
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NPD
THE NITROGEN PHOSPHORUS DETECTOR IS A
SELECTIVE DETECTOR FOR NITROGEN AND
PHOSPHORUS-CONTAINING COMPOUND.ITS
DETECTION PRINCIPLE APPEARS TO BE BASED
ON THE ELECTRONIC CONDUCTIVITY OF A
FLAME IN THE PRESENCE OF AN ALKALI METAL
SALTS AND CHANGES THEREIN CAUSED BY
NITROGEN OR PHOSPHORUS IN THE
COMPOUNDS ENTERING THE DETECTORS.
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ECD
AN ELECTRON CAPTURING DETECTOR IS A
DEVICE FOR DETECTING ATOMS AND
MOLECULES IN A GAS THROUGH THE
ATTACHMENT OF ELECTRONS VIA ELECTRON
CAPTURE IONOZATION .IT IS USED TO DETECT
TRACE AMOUNT OF CHEMICAL COMPOUNDS.
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STRUCTURE OF NPD
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WORKING PRINCIPLE OF NPD

USES HYDROGEN/AIR FLAME THROUGH
WHICH THIS SAMPLE IS PASSED

USES RUBIDIUM/CESIUM BEAD WHICH IS
HEATED BY A COIL OVER WHICH THE
CARRIER GAS MIXED WITH HYDROGEN
PASSES

THE HOT BEAD EMITS ELECTRONS BY
WHICH ARE COLLECTED AT THE ANODE
AND PROVIDES THE BACKROUND CURRENT.

WHEN A COMPONENTS THAT CONTAIN N/P
EXITS THE COLUMN,THE PARTIALLY
COMBUSTED N/P MATERIALS ARE
ADSORBED ON THE SURFACE OF THE BEAD.

THIS THEN INCREASES THE EMISSION OF
ELECTRONS.
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ADVANTAGES OF NPD

THE SPECIFIC RESPONSE OF NPD TO NITROGEN AND PHOSPHORUS ,WITH
RELATIVELY HIGH SENSITIVITY ,MAKES IT USEFUL FOR ANYLISIS OF
PHARMACEUTICALS.

IN ENVIRONMENTAL ANALYSIS INVOLVING HERBICIDES

DOES NOT DETECT COMMON MOBILE PHASE IMPURITIES OR CARRIER GASES

USEFUL FOR DRUG ANALYSIS

MORE SENSITIVE TO HETEROCOMPOUNDS
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DISADVANTAGES OF NPD

PERFOMANCE DETERIORATES WITH TIME

BURNING HYDROGEN VAPOUR CONVERTS ALKALI SILICATE TO AKLALI
HYDROXYDE WHICH HAS SIGNIFICANT VAPOUR PRESSURE AND CAUSES LOSS OF
CESIUM/RUBIDIUM

DESTRUCTIVE DETECTOR

LESS SENSITIVE TO ORGANIC COMPOUNDS COMPARED TO FID
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STRUCTURE OF ECD
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WORKING PRINCIPLE

A BEAM IS PRODUCED BY THE BETA
EMMITER

WHEN CARRIER GASPASSES OVER THE
EMITTER,THE GAS IONISES PRODUCING
ELECTRONS.

IN ABSENCE OF COMPOUND IONIZATION OF
CARRIER GAS PRODUCES A CONSTANT
STANDING CURRENT.

WHEN SOLUTE IS ELUTED OUT FROM THE
COLUMN ,IT CAPTURES ELECTRONS
TOWARDS IT, HENCE CURRENT DECREASES

THIS DECREASE GIVES IDEA ABOUT THE
CONCENTRATION OF A SOLUTE IN THE
SAMPLE
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ADVANTAGES OF ECD

DETECTION AND DETERMINATION OF CHLORINATED INSECTICIDES.

DOES NOT ALTER THE SAMPLE

HIGHLY SENSITIVE TOWARDS COMPOUNDS CONTAINING ELECTRONEGATIVE
FUNCTIONAL GROUPS SUCH AS HALOGENS,PEROXIDES,NITRO ETC

THE ECD IS SELECTIVE TO ITS RESPONSE

IT IS NON DESTRUCTIVE

MORE SENSITIVE THAN TCD AND FID
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DISADVANTAGES OF ECD

LEAST SENSITIVE TO COMPOUNDSWHOSE MOLECULES HAVE NEGLIGIBLE
AFFINITY FOR ELECTRONS.

CARRIER GASUSED SHOULD BE OF PURE GAS FORM

NON LINEAR RESPONSE UNLESS POTENTIAL ACROSS THE DETECTOR IS PULSED
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COMPARE AND CONTRAST PRINCIPLES OF
ECD AND NPD
ECD

IT IS USED IN ENVIRONMENTAL
TESTING

MORE SENSITIVE THAN FID FOR
MOLECULES CONTAINING
ELECTRONEGATIVE FUNCTIONAL
GROUPS
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NPD

USED IN ANYLIS FOR
FOOD,FORENSIC AND
ENVIROMENTAL SAMPLES

VERY SENSITIVE TO NITROGEN AND
PHOSPHORUS CONTAINING
MOLECULE
COMPARE AND CONTRAST INSTRUMENTATION
PRINCIPLES OF ECD AND NPD
ECD

USES A RADIOACTIVE SOURCE TO
SEND CONSTANT CURRENT
ELECTRONS ACROSS THE MOBILE
PHASE.ONCE A COMPOUND ENTERS
THE CURRENT IT BEGIND TO
CAPTURE ELECTRONS WHICH
DECREASE THE CURRENT.
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NPD

BASED ON THE ELECTRONIC
CONDUCTIVITY OF AFLAME IN THE
PPRESENCE OF AN ALKALI METAL
SALTS AND CHANGES THEREIN
CAUSED BY NITROGEN OR
PHOSPHORUS IN THE COMPOUND
ENTERING THR DETECTORS.THEN
THIS INCREASES THE EMISSION OF
ELECTRONS.
CONCLUSION

NPD IS A SELECTIVE DETECTOR FOR NITROGEN AND PHOSPHORUS HENCE IT IS
MORE SENSITIVE TOWARDS THEM.ITS BASED ON ELECTRONIOC CONDUCTIVITY
IN THE PRSENCE OF AN ALKALI EARTH METAL SALT AND IT IS MOSTLY USED IN
ANALYSIS OF SAMPLES

ECD USES ELECTRON CAPTURE IONISATION TO CAPTURE ATOMS AND TO DETECT
THE AMOUNT OF CHEMICAL COMPOUND.IT USES RADIOACTIVE SOURCE TO SEND
CONSTANT CURRENT OF ELECTRONS ACROSS THE MOBILE.IT IS HIGHLY
SENSITIVE TOWARDS ELECTRONEGATIVE FUNCTIONAL GROUPS AND IS USED FOR
ENVIRONMENTAL TESTING
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REFFERENCES

SLIDEPLAYER.COM

INSTRUMENTATION—GC-ECD-BERKELEY

HTTP://EN.M.WIKIPEDIA.ORG/WIKI/INSTRUMENTATION

SLIDETODOC.COM

COMMUNITY.ASDLIB.ORG

SLIDESHARECDN.COM

CHROMEDIA.ORG

SHIMADZU.COM

LABTRAINING.COM

RESEARCHGATE.NET
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