Name: atomic emission spectroscopy for element analysis
Uploaded: 2024-12-05T18:32:15.000Z
Duration: 1 min 20 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Earth and Space Science

Space Systems

3.3.9-12.C

Atomic Emission Spectroscopy: Overview

Атомно-эмиссионная спектроскопия, или AES, позволяет проводить многоэлементный анализ образца, в котором все аналиты могут возбуждаться одновременно электрическим разрядом, пламенем или плазмой.
В AES атомы в возбужденном состоянии расслабляются, образуя характерные излучения, а интенсивность излучения прямо пропорциональна популяции возбужденного состояния.
Значительные популяции атомов в возбужденном состоянии достигаются за счет использования высокотемпературной аргоновой плазмы.
Аргоновая плазма — горячая, электропроводящая газообразная смесь ионов аргона и электронов — образуется путем ионизации проточного потока аргона. Плазма поддерживается в течение неограниченного времени источником питания, который поддерживает оптимальную температуру для дальнейшей ионизации. 
Радиочастотный источник плазмы, называемый индуктивно связанной плазмой, может достигать температуры до 10 000 К. Это широко используемый источник возбуждения в AES, обычно называемый ICP-AES или ICP-OES.
Другие источники плазмы включают микроволновую плазму, плазму постоянного тока, микроплазму и лазерно-индуцированную плазму.

Атомно-эмиссионная спектроскопия: обзор

Атомно-эмиссионная спектроскопия (АЭС) — это аналитический метод, используемый для определения элементного состава образца путем анализа света, испускаемого возбужденными атомами. В АЭС атомы в образце возбуждаются до более высоких энергетических уровней тепловой энергией от высокотемпературных источников, таких как плазма, дуги или искры. Когда эти возбужденные атомы возвращаются в более низкие энергетические состояния, они излучают свет на определенных длинах волн, характерных для каждого элемента. Результирующий спектр атомной эмиссии, который состоит из дискретных линий, соответствующих этим длинам волн, позволяет идентифицировать и количественно определять содержание различных элементов в образце.

Аппаратура АЭС имеет сходство с атомно-абсорбционными спектрометрами, но со специальными приспособлениями для обнаружения излучения. Высокотемпературные источники, в частности индуктивно связанная плазма (ИСП), необходимы в АЭС, поскольку они достигают достаточной энергии для возбуждения атомов до их состояний излучения. Другие источники плазмы включают микроволновую плазму (МИП) и плазму постоянного тока (ППТ). Наиболее широко используемый источник, ИСП, достигает температур до 10 000 К, создавая стабильную среду для постоянного возбуждения и испускания. ИСП-АЭС, также известная как ИСП-ОЭС (оптическая эмиссионная спектрометрия), позволяет проводить многоэлементный анализ, размещая несколько детекторов в полукруглой решетке вокруг источника испускания для одновременного получения показаний в диапазоне длин волн.

АЭС имеет несколько преимуществ по сравнению с традиционными методами атомной абсорбции, такими как пламенные и электротермические методы. Благодаря высокотемпературным источникам, которые диссоциируют сложные молекулы, АЭС менее восприимчив к химическим помехам, что обеспечивает более чистые спектральные показания. Этот метод позволяет проводить одновременный многоэлементный анализ, значительно повышая аналитическую эффективность. Кроме того, АЭС охватывает более широкий диапазон концентраций, что делает его пригодным для различных типов образцов.

Несмотря на эти преимущества, АЭС имеет ограничения. Сложные спектры, создаваемые высокотемпературными источниками, увеличивают вероятность спектральных помех, что усложняет количественный анализ. Для решения этих задач приборам АЭС требуются оптические системы высокого разрешения, часто более дорогие, чем те, которые используются в атомно-абсорбционной спектрометрии. Кроме того, хотя АЭС является мощным инструментом для многоэлементного анализа, методы атомной абсорбции остаются ценными для одноэлементного анализа благодаря своей простоте, экономической эффективности и точности.

АЭС широко используется в мониторинге окружающей среды, материаловедении и клинических лабораториях для анализа металлов, микроэлементов и других неорганических веществ. Его способность выполнять быстрый многоэлементный анализ делает АЭС особенно полезным для тестирования почв, воды и биологических образцов. Высокая чувствительность и широкий элементный диапазон инструментов АЭС позволяют проводить точные измерения как при следовых, так и при значительных концентрациях, что делает его универсальным инструментом для элементного анализа в различных научных областях.

В АЭС количественный анализ основан на измерении интенсивности испускаемого света, которая пропорциональна популяции возбужденных атомов. Согласно распределению Больцмана, эта популяция возбужденного состояния зависит от температуры источника возбуждения, причем более высокие температуры дают большую эмиссию. Калибровочные кривые, часто линейные в широком диапазоне значений, создаются путем анализа известных стандартов для корреляции интенсивности эмиссии с концентрацией элементов. Методы стандартизации имеют решающее значение для контроля изменений в эффективности возбуждения и других инструментальных факторов, позволяя проводить точную количественную оценку элементов в различных образцах.

Атомно-эмиссионная спектроскопия (AES) — это аналитический метод, используемый для определения элементного состава образца путем анализа света, испускаемого ...

Education

JoVE Core

Analytical Chemistry

Аналитическая химия

Unit 1

Раздел 1

Atomic Spectroscopy

Атомная спектроскопия

KEY TERMS AND CONCEPTS

ОСНОВНЫЕ ТЕРМИНЫ И ПОНЯТИЯ

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, but they are built to detect emitted light. High-temperature sources are essential because they provide enough energy to excite atoms into their emission states. Inductively coupled plasma, or ICP, is the most widely used source. It can reach temperatures up to 10,000 K and creates a stable environment for steady excitation and emission. Other plasma sources used in AES include microwave-induced plasma, or MIP, and direct current plasma, or DCP.

ICP-AES is also called ICP-OES, which stands for optical emission spectrometry. This setup allows multielement analysis by placing multiple detectors in a semicircular array around the emission source. The detectors can record several wavelengths at the same time. That makes the method fast and useful when more than one element must be measured in the same sample.

AES has several advantages over traditional atomic absorption methods such as flame and electrothermal techniques. The high-temperature source helps break apart complex molecules, so chemical interferences are usually lower. The method also supports simultaneous multielement analysis, which improves efficiency. In addition, AES covers a wider concentration range, so it works with many different sample types.

The technique also has limits. High-temperature sources create complex spectra, which increases the chance of spectral interferences and can make quantitative analysis harder. AES instruments need high-resolution optical systems to separate the lines clearly, and these systems are often more expensive than those used in atomic absorption spectrometry. For single-element analysis, atomic absorption methods are still useful because they are simple, cost-effective, and precise.

AES is widely used in environmental monitoring, materials science, and clinical laboratories. It can analyze metals, trace elements, and other inorganic substances in soil, water, and biological samples. This makes it valuable for rapid testing across many scientific fields. The method is sensitive and can measure both trace and significant concentrations.

Quantitative AES depends on the intensity of the emitted light. That intensity is related to the number of atoms in the excited state. According to the Boltzmann distribution, this excited-state population depends on the temperature of the source, so higher temperatures produce more emission. To find concentration, scientists use calibration curves made from known standards, and they apply standardization methods to reduce the effects of changes in excitation efficiency and other instrument factors.

Atomic Emission Spectroscopy for Element Analysis

atomic-emission-spectroscopy-for-element-analysis

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 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

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...

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 atomic emission spectroscopy uses emitted light to identify elements, compare ICP-AES and ICP-OES, and measure samples with calibration curves.

Atomic Emission Spectroscopy for Element Analysis | JoVE K12

analytical chemistry

JoVE Core Analytical Chemistry simplifies complex chemical principles by breaking them down into clear, engaging animations, making topics from SI Units to NMR spectroscopy more accessible and straightforward. Additionally, the scientist-in-action videos highlight the application of these concepts in real-world research conducted in laboratories globally.

Louisiana Student Standards for Science

High School

Earth Science

Earth’s Place In The Universe

HS-ESS1-2

Chemistry

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HS-PS2-6

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South Carolina College and Career Ready Science Standards

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Waves and Their Applications in Technologies for Information Transfer

C-PS4-4

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3.3.9-12.A

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Atomic Emission Spectroscopy: Instrumentation

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Atomic Absorption Spectroscopy: Radiation and Light Sources

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3.3.9-12.B

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3.3.9-12.D

Atomic Emission Spectroscopy for Element Analysis

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