Name: icp-aes torch and sample analysis
Uploaded: 2024-12-05T18:32:15.000Z
Duration: 1 min 19 s
Channel: JoVE

电感耦合等离子体（ICP）是原子发射光谱分析中广泛使用的一种等离子体源。
它采用等离子体炬，由三个同心石英管组成，通有流动的氩气，并通过特斯拉线圈产生的火花使氩气电离。
所产生的离子和电子与由水冷射频感应线圈产生的交变磁场相互作用。
这种相互作用导致欧姆加热，形成高温氩等离子体，其具有明亮的白色核心和类似火焰的尾部。
在电感耦合等离子体原子发射光谱法（ICP–AES）中，使用同心玻璃雾化器在高速氩气的辅助下将样品输送，并通过伯努利效应形成细小液滴进入等离子体。
或者可以采用电热汽化法，即将样品在炉中汽化，再由氩气流将其带入等离子体中。
等离子体源具有多种优势，例如可在化学惰性环境中实现原子化，防止难熔氧化物的形成，并延长分析物的寿命。
此外，它能保持相对均匀的温度截面，从而减少自吸收和自反转现象的发生。

电感耦合等离子体原子发射光谱法：原理

Inductively Coupled Plasma Atomic Emission Spectroscopy: Principle

在原子发射光谱（AES）中，电感耦合等离子体（ICP）是使用最为广泛的等离子体源，也被称为电感耦合等离子体发射光谱（ICP-OES）。电感耦合等离子体源（又称电感耦合等离子体炬管）是由三个同心石英管所组成的，并且管内有氩气流过。特斯拉线圈内产生的火花引发了氩气的电离，从而使其能够产生高温等离子体。


 由射频发生器驱动的水冷感应线圈所产生的波动磁场将会与产生的离子和电子发生相互作用。这种相互作用将会导致出现欧姆加热，同时形成高温等离子体，从而使其能够为元素分析提供最佳环境。可以使用不同的方法来实现电感耦合等离子体原子发射光谱（ICP-AES）中的样品引入，例如同心玻璃雾化器或电热蒸发法。在同心玻璃雾化器中，样品会通过伯努利效应在高速氩气的帮助下进行传输，从而使其能够形成细小的液滴来进入等离子体。在电热蒸发法中，样品首先会在熔炉中蒸发，然后通过氩气流进入到等离子体。


 电感耦合等离子体光谱仪的观察方式分为垂直观测或水平观测。在水平方向、轴向观测的等离子体是高灵敏度分析的理想方式。它不仅具有独特的冷锥接口（CCI），而且能够使光学元件无需考虑较冷的等离子体尾部，从而使其能够减少干扰并提高系统对高溶解性固体的耐受性。垂直方向、垂直观测的等离子体适用于具有挑战性的应用，例如对油、有机溶剂、地质/金属消化物和较高的总溶解固体（TDS）溶液所进行的分析。


 等温轮廓线描绘了样品原子在到达观察点之前在等离子体中停留时间内所经历的温度范围。这将会使得原子化变得更完全，化学干扰更少。原子发射光谱中的电感耦合等离子体源具有众多优势，其中包括：化学惰性原子化、均匀的温度分布、宽浓度范围内的线性校准曲线和显著的电离效果，这使其能够成为电感耦合等离子体-质谱法（ICP-MS）应用的绝佳选择。

电感耦合等离子体（ICP）是原子发射光谱法（AES）中最广泛使用的等离子体源，也称为电感耦合等离子体…

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

Education

教育

JoVE Core

Analytical Chemistry

分析化学

Unit 1

第一单元

Atomic Spectroscopy

原子光谱

KEY TERMS AND CONCEPTS

关键术语与概念

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 charged particles then interact with the changing magnetic field from a water-cooled induction coil powered by a radio-frequency generator. This interaction produces ohmic heating, which helps keep the plasma hot.

Samples can enter the plasma in more than one way. A concentric glass nebulizer uses high-velocity argon gas and the Bernoulli effect to carry the sample as fine droplets. Another method is electrothermal vaporization, where the sample is first vaporized in a furnace and then sent into the plasma with argon gas.

ICP spectrometers can use radial or axial viewing. Horizontally oriented, axially viewed plasma is better for high-sensitivity work. It uses a cooled cone interface, or CCI, to keep the optics from using the cooler tail of the plasma. This reduces interference and helps the system handle samples with high dissolved solids. Vertically oriented, radially viewed plasma is useful for difficult samples such as oils, organic solvents, geological or metal digests, and solutions with high total dissolved solids, or TDS.

Isothermal contours show the temperature range that sample atoms experience while they stay in the plasma before reaching the observation point. This helps produce more complete atomization and fewer chemical interferences. The ICP source also offers chemically inert atomization, a uniform temperature distribution, linear calibration curves over a wide range of concentrations, and strong ionization. These features make ICP a useful source for ICP-MS applications as well.

ICP-AES Torch and Sample 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 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 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 the ICP torch, argon plasma, sample introduction, and axial or radial viewing support elemental analysis in ICP-AES and ICP-OES.

ICP-AES Torch and Sample Analysis | JoVE K12

analytical chemistry

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ICP-AES Torch and Sample Analysis

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