Name: icp-aes instrument types and detection
Uploaded: 2024-12-05T18:32:15.000Z
Duration: 1 min 26 s
Channel: JoVE

Bei der Plasmaemissionsspektroskopie werden drei grundlegende Gerätetypen verwendet.
Sequentielle Plasmaemissionsspektrometer messen jeweils eine Emissionslinie, während Mehrkanal- und Fourier-Transformationsinstrumente gleichzeitig mehrere Emissionslinien messen.
Sequentielle Spektrometer verwenden in der Regel einen Gittermonochromator, bei dem das Gitter gedreht wird, um verschiedene Wellenlängen auf den Austrittsspalt zu fokussieren.
Bei Slew-Scan-Spektrometern dreht sich der Monochromator beispielsweise schnell auf eine Wellenlänge nahe einer Emissionslinie und dreht sich dann in kleinen Schritten über diese Linie.
Im Gegensatz dazu haben Rasterechelle-Spektrometer ein bewegliches Photomultiplierrohr hinter einer Aperturplatte, wobei das Echelle-Gitter die Wellenlängen in einem breiten Array streut, das schlitzweise detektiert werden kann.
Einige Mehrkanalgeräte verwenden einen Gitter-Polychromator, um mehrere Emissionslinien gleichzeitig mit Photomultiplier-Röhren zu messen, die hinter festen Ausgangsschlitzen positioniert sind.
Andere Mehrkanalgeräte verwenden Spektrographen für gleichzeitige Messungen und verwenden zweidimensionale Ladungsinjektionsgeräte oder ladungsgekoppelte Geräte als Wandler.
Obwohl Fourier-Transformationsspektrometer eine breite Wellenlängenabdeckung bieten, werden sie aufgrund ihrer verschiedenen Einschränkungen in der AES nicht häufig eingesetzt.

induktiv gekoppelte plasma-atomemissionsspektroskopie: instrumentierung

Inductively Coupled Plasma Atomic Emission Spectroscopy: Instrumentation

Induktiv gekoppeltes Plasma (ICP) ist die meistverwendete  Plasmaquelle für die Atomemissionsspektroskopie (AES), eine Technik, die verschiedene Elemente in einer Probe detektiert und analysiert. Diese Methode wird oft als induktiv gekoppelte Plasma-Atomemissionsspektroskopie (ICP-AES) bezeichnet.

Es gibt drei Haupttypen von Instrumenten für die induktiv gekoppelte Plasma-Atomemissionsspektroskopie (ICP-AES): sequentielle, simultane Mehrkanal- und Fourier-Transformations-Instrumente, wobei letztere weniger häufig verwendet werden. Bei der sequentiellen ICP-AES wird jedes Element einzeln analysiert, wobei das Instrument so programmiert ist, dass es von einer Emissionslinie zur nächsten wechselt und bei jeder Linie einige Sekunden stoppt, um die Linienintensitäten ausreichend genau zu messen. Mehrkanalinstrumente hingegen sind darauf ausgelegt, die Intensitäten der Emissionslinien mehrerer Elemente gleichzeitig oder nahezu gleichzeitig zu messen. Sequentielle Instrumente sind zwar in ihrer Funktion einfacher, erfordern jedoch mehr Zeit und größeren Probenverbrauch, was sie auf lange Sicht teurer macht.

Sequentielle und mehrkanal Emissionsspektrometer können entweder ein klassisches Gitterspektrometer oder ein Echelle-Spektrometer verwenden. Gittermonochromatoren, die häufig in sequentiellen Instrumenten verbaut werden, verwenden ein holografisches Gitter mit 2400 oder 3600 Rillen pro Millimeter. Das Gitter wird mit einem digital gesteuerten Schrittmotor gedreht, um verschiedene Wellenlängen sequentiell und präzise auf den Austrittsspalt zu fokussieren. Slew-Scan-Spektrometer sind sequentielle Instrumente, die sehr schnell bis zu einer Wellenlänge in der Nähe der gewünschten Linie scannen, bevor sie langsamer werden, um anschließend die Linie in kleinen Schritten zu scannen. Diese Methode minimiert die Zeit, die in nicht relevanten Wellenlängenbereichen verbracht wird.

Echelle-Spektrometer wiederum werden entweder als Scan-Instrument oder als simultanes Mehrkanal-Spektrometer betrieben. Simultane Mehrkanalinstrumente enthalten entweder einen Polychromator oder einen Spektrographen. Polychromatoren enthalten eine Reihe von Photomultiplierröhren zur Detektion, Spektrographen verwenden jedoch zweidimensionale charge-injection devices (CIDs) oder charge-coupled devices (CCDs) als Wandler. In einigen Mehrkanal-Emissionsspektrometern befinden sich Photomultiplier hinter fixen Austrittsspalten entlang der Brennebene eines Gitterpolychromators.

Obwohl sie in der AES nicht weit verbreitet sind, bieten Fourier-Transformationsspektrometer Vorteile wie einen breiten Wellenlängenbereich, Geschwindigkeit, hohe Auflösung, präzise Wellenlängenmessungen, einen großen Dynamikbereich, kompakte Baumaße und einen großen optischen Durchsatz. Insgesamt bieten AES-Instrumente unterschiedliche Funktionen, von sequentiellem Scannen bis hin zur simultanen Mehrkanaldetektion und Fourier-Transformationsanalyse, sodass Forscher und Analytiker den für ihre spezifischen Analyseanforderungen am besten geeigneten Ansatz wählen können.

Induktiv gekoppelte Plasma-Atomemissionsspektroskopie: Instrumentierung

Induktiv gekoppeltes Plasma (ICP) ist die gebräuchliche Plasmaquelle, die in der Atomemissionsspektroskopie (AES) verwendet wird, einer Technik, die verschiedene ...

inductively-coupled-plasma-atomic-emission-spectroscopy

Education

Lehre

JoVE Core

Analytical Chemistry

Analytische Chemie

Unit 1

Einheit 1

Atomic Spectroscopy

Atomspektroskopie

KEY TERMS AND CONCEPTS

WICHTIGE BEGRIFFE UND KONZEPTE

icp-aes instrument types and detection

Inductively coupled plasma atomic emission spectroscopy, or ICP-AES, uses an inductively coupled plasma to detect and analyze elements in a sample. The method measures the light given off by atoms, which helps identify and compare different elements. It is a common approach in atomic emission spectroscopy.

ICP-AES instruments are built in three main forms: sequential, simultaneous multichannel, and Fourier transform instruments. Fourier transform designs are less commonly used, but they are part of the instrument family. Each type handles wavelengths and element signals in a different way.

Sequential ICP-AES measures elements one at a time. The instrument moves from one element line to another and pauses for a few seconds at each point so it can measure line intensity well. These instruments are simpler, but they take more time and use more sample, so they can cost more over time.

Multichannel instruments measure emission lines for several elements at the same time, or nearly at the same time. Sequential and multichannel emission spectrometers can use either a classical grating spectrometer or an echelle spectrometer. In many sequential instruments, a grating monochromator uses a holographic grating with 2400 or 3600 grooves per millimeter, and a digitally controlled stepper motor rotates the grating to send different wavelengths to the exit slit.

Some sequential systems are slew-scan spectrometers. They move quickly to a wavelength near the line of interest and then slow down to scan across the line in small steps. This reduces time spent in wavelength regions that do not help the measurement.

An echelle spectrometer can work as a scanning instrument or as a simultaneous multichannel spectrometer. Simultaneous multichannel instruments may use a polychromator or a spectrograph. Polychromators use a series of photomultiplier tubes, while spectrographs use two-dimensional charge-injection devices, or CIDs, and charge-coupled devices, or CCDs, as transducers.

In some multichannel emission spectrometers, photomultipliers sit behind fixed slits along the focal curve of a grating polychromator. Fourier transform spectrometers are not widely used in AES, but they offer wide wavelength coverage, speed, high resolution, accurate wavelength measurements, a large dynamic range, compact size, and high optical throughput. These instrument choices let analysts match the system to the needs of a specific sample and measurement.

ICP-AES Instrument Types and Detection

atomic spectroscopy: absorption, emission, and fluorescence

atomic-spectroscopy-absorption-emission-and-fluorescence

Element Analysis with Atomic Light Spectra

Atomic spectroscopy is used to identify and measure elements by their light signals. It supports both qualitative analysis, which tells what is present, and quantitative analysis, which tells how much is present. The optical methods in this group are atomic absorption spectroscopy, atomic emission spectroscopy, and atomic fluorescence spectroscopy. These methods begin with atomization. In this step, a solid, liquid, or solution sample is changed into gas-phase atoms and ions. Once the sample...

atomic spectroscopy: effects of temperature

atomic-spectroscopy-effects-of-temperature

How Heat Changes Atomic Spectra

Heat changes atomic spectra by affecting atomization, excitation, ionization, and line shape. In atomic spectroscopy, atomization means converting a sample into gas-phase atoms and ions. The flame temperature needed for this step changes how efficiently the method works and shifts the balance between excited and ground-state atoms. At thermal equilibrium, the relative numbers of excited and ground-state atoms can be estimated with the Maxwell-Boltzmann distribution. A small temperature rise...

atomic absorption spectroscopy: overview

Atomic Absorption Spectroscopy for Trace Metals

Atomic absorption spectroscopy (AAS) measures trace metals by tracking how atoms absorb electromagnetic radiation (EMR). The absorbed light makes atoms move to a higher-energy orbit. In AAS, the key step is atomization, which converts the sample into gas-phase atoms. A flame or a furnace is typically used for this step. Inside the flame, some atoms become thermally excited. Most stay in the ground state, which is the lowest-energy state. These ground-state gas-phase atoms absorb EMR only when...

atomic absorption spectroscopy: instrumentation

atomic-absorption-spectroscopy-instrumentation

Atomic Absorption Spectroscopy: Key Parts

Atomic absorption spectrophotometry uses a set of key parts to measure light absorbed by atoms. The main components are a radiation source, an atomizer, a monochromator, and a detector. Each part has a specific job in the instrument. The radiation source is usually a hollow-cathode lamp, or HCL, or an electrodeless-discharge lamp, or EDL. Both produce a narrow emission line at the needed wavelength. Some instruments instead use continuum sources with high-resolution monochromators to narrow...

atomic absorption spectroscopy: radiation and light sources

atomic-absorption-spectroscopy-radiation-and-light-sources

Choosing Light Sources for AAS Measurements

Atomic absorption spectroscopy (AAS) uses a light source that emits a very narrow range of wavelengths. This is needed because the source must match the absorption behavior of the analyte atom. The choice of source also depends on giving a precise, intense emission at the right wavelength for accurate detection. Two common line sources in AAS are hollow-cathode lamps (HCLs) and electrodeless-discharge lamps (EDLs). These lamps are selected based on the element being analyzed and the level of...

atomic absorption spectroscopy: atomization methods

atomic-absorption-spectroscopy-atomization-methods

Atomic Absorption Spectroscopy: Sample Atomization

Atomic absorption spectroscopy uses sample atomization to turn a liquid specimen into free atoms for analysis. The two main approaches are flame atomization and electrothermal atomization. Both methods prepare the sample so its atoms can be measured by the instrument. Flame atomization uses a nebulizer and spray chamber to mix the sample with a fuel-oxidant mixture. This creates a fine aerosol mist that enters the burner. The fuel and oxidant are usually close to a stoichiometric ratio, but a...

atomic absorption spectroscopy: interference

atomic-absorption-spectroscopy-interference

Correcting Errors in Atomic Absorption Spectroscopy

Atomic absorption spectroscopy interference can create systematic error by making the analytical signal or the background look stronger or weaker than it should be. In atomic absorption measurements, these errors are usually grouped as spectral interference, chemical interference, and physical interference. Spectral interference happens when signals from other elements or molecules overlap with the analyte signal, the substance being measured. This overlap can falsely raise or hide the analyte...

atomic absorption spectroscopy: lab

AAS Sample Prep and Calibration

Atomic absorption spectroscopy (AAS) depends on careful sample preparation and calibration. Samples must be turned into clear solutions before measurement. That often means extra treatment to dissolve materials such as soils, animal tissues, and minerals. Common sample prep methods include hot mineral acids, wet ashing, combustion in closed containers, high-temperature ashing, and fusion with reagents. These steps help make the sample suitable for AAS analysis. Solutions that contain organic...

atomic emission spectroscopy: overview

Atomic Emission Spectroscopy for Element Analysis

Atomic emission spectroscopy is used to identify the elements in a sample by measuring the light they emit. Atoms are first excited to higher energy levels by thermal energy from hot sources such as plasma, arcs, or sparks. When they fall back to lower energy levels, they give off light at specific wavelengths. Each element produces its own set of lines, so the emission spectrum can show both what is present and how much is there. AES instruments are similar to atomic absorption spectrometers,...

atomic emission spectroscopy: instrumentation

atomic-emission-spectroscopy-instrumentation

AES Sample Handling and Detection

Atomic emission spectrometry (AES) uses sample handling, atomization, and detection parts to measure emitted light from atoms and ions. The sample must first be changed into a gas-phase form so it can produce a measurable signal. AES uses two main atomizer types. Continuous atomizers, such as flames and plasmas, feed the sample in a steady stream. Discrete atomizers add one sample at a time with syringes or autosamplers. The electrothermal atomizer is the most common discrete type. Many...

atomic emission spectroscopy: interference

atomic-emission-spectroscopy-interference

Reducing Interference in AES Signals

Atomic emission spectroscopy (AES) can produce interfering signals when atoms and molecules in a flame or plasma emit overlapping light. High-temperature atomizers excite many species at once, including oxides, hydroxides, and flame combustion products. These extra emissions can make the analyte signal harder to read. Spectral interference happens when emission lines or bands overlap. One way to reduce it is to improve instrument resolution. Another is to choose a different emission line for...

inductively coupled plasma atomic emission spectroscopy: principle

inductively-coupled-plasma-atomic-emission-spectroscopy-principle

ICP-AES Torch and Sample Analysis

Inductively coupled plasma atomic emission spectroscopy uses a plasma torch to analyze elements in a sample. This method is also called inductively coupled plasma optical emission spectroscopy, or ICP-OES. It is widely used because the plasma creates a strong environment for elemental analysis. The ICP source, or torch, contains three concentric quartz tubes. Argon gas flows through the tubes. A spark from a Tesla coil starts the ionization of argon and creates a high-temperature plasma. The...

inductively coupled plasma atomic emission spectroscopy: instrumentation

Inductively coupled plasma atomic emission spectroscopy, or ICP-AES, uses an inductively coupled plasma to detect and analyze elements in a sample. The method measures the light given off by atoms, which helps identify and compare different elements. It is a common approach in atomic emission spectroscopy. ICP-AES instruments are built in three main forms: sequential, simultaneous multichannel, and Fourier transform instruments. Fourier transform designs are less commonly used, but they are...

atomic emission spectroscopy: lab

Plasma Sources in Atomic Emission Spectroscopy

Atomic emission spectroscopy uses plasma sources to identify elements by their light. The method creates abundant spectra with characteristic emission lines. Inductively coupled plasma, or ICP, is especially useful because it gives strong quantitative data. It works well under stable conditions, with low noise, low background, and few interferences. Newer air-operated microwave sources are also being studied. These sources may be more cost-effective than conventional ICP systems. Atomic...

atomic fluorescence spectroscopy

Measuring Elements by Atomic Fluorescence

Atomic fluorescence spectroscopy measures elements by detecting the light atoms give off after they are excited by electromagnetic radiation. The atoms are first placed in a flame, furnace, or plasma. They absorb energy, become excited, and then release that energy as they return to their original state. The emitted light is called fluorescence. The fluorescence is observed at a right angle to the incoming beam. This setup helps separate the emitted light from the light used to excite the...

flame photometry: overview

Flame Emission Spectrometry Basics

Flame emission spectrometry uses a flame to excite elements in a sample so their light can be measured. It is also called flame photometry. The method can be used for both qualitative and quantitative analysis of elements. The idea became established in the early 1860s when Kirchhoff and Bunsen showed that specific elements give off characteristic radiation in a flame. The first instrument for this purpose measured sodium in plant ash with a Bunsen flame. A major problem was how to add the...

flame photometry: lab

Flame Photometry and Metal Detection

Flame photometry is a method for detecting metals by measuring the light they emit in a flame. A solution such as potassium chloride is aspirated into the flame. The solvent evaporates first. The remaining salt becomes dehydrated and then dissociates into free gaseous atoms in the ground state. Some of these atoms absorb energy from the flame and move to an excited state. When they return to the ground state, they emit photons at characteristic wavelengths. These emissions are very narrow...

key terms and concepts

Learn how ICP-AES instruments work, including sequential, multichannel, and Fourier transform designs, plus the detectors and spectrometers used to measure elements.

ICP-AES Instrument Types and Detection | JoVE K12

analytical chemistry

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ICP-AES Instrument Types and Detection

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