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        <header id="main-header" style="text-align:center;">Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
        </header>
        <div id="space-invader"></div>

        <section class="main-section icp-header">
            <p class="space-p" style="text-align:justify;">Inductively coupled plasma mass spectrometry (ICP-MS) is an
                elemental analysis technology capable of detecting most of the periodic table of elements at milligram
                to nanogram levels per liter. It is used in a variety of industries including, but not limited to,
                environmental monitoring, geochemical analysis, metallurgy, pharmaceutical analysis, and clinical
                research.
            </p>
        </section>

        <main class="content" id="main-doc">
            <section class="main-section" id="ICP-MS_in_An_Overall_Nutshell">
                <header>ICP-MS in An Overall Nutshell</header><br>
                <header class="subheader">What is inductively coupled plasma? </header>
                <article class="clearfix">
                    <div class="flex-test">
                        <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/jcr:content/MainParsys/image_267c/foregroundimg.img.320.high.jpg/1603737298068.jpg"
                            alt="icp-image" class="icp-intro-image left">

                        <p>The Inductively Coupled Plasma (ICP) is an ionization source that fully decomposes a sample
                            into its constituent elements and transforms those elements into ions. It is typically
                            composed of argon gas, and energy is "coupled" to it using an induction coil to form the
                            plasma.
                        </p>
                    </div>
                </article>
            </section>

            <section class="main-sections" id="ICP-MS_trace_metals_analysis_workflow">
                <header class="subheader">ICP-MS trace metals analysis workflow
                </header>
                <article>
                    <p> <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/jcr:content/MainParsys/image_f14/foregroundimg.img.320.low.jpg/1603737298163.jpg"
                            alt="ICP-MS workflow" class="icp-intro-image right">
                        ICP-MS systems are powerful analytical instruments; to obtain the best quality of data from
                        these instruments, sample preparation and introduction methods must be performed with care.
                        Also, data acquisition and processing should be thoroughly scrutinized.
                    </p>
                    <p>In this section, you will:
                    <ul class="into-ul clearfix">
                        <li class="intro-li">Foster understanding in the field of analytical chemistry by applying
                            ICP-MS</li>
                        <li class="intro-li">Learn which sample types can be analyzed by ICP-MS and what sample
                            preparation and introduction conditions must be considered</li>
                        <li class="intro-li">Know how ICP-MS data are generated inside the mass analyzer, prior to being
                            collected for analysis</li>
                        <li class="intro-li">Recognize and correct for factors that interfere with accurate ICP-MS data
                            analysis</li>
                        <li class="intro-li">Understand the systems and technology that drive <a
                                href="https://www.thermofisher.com/fi/en/home/industrial/mass-spectrometry/inductively-coupled-plasma-mass-spectrometry-icp-ms.html"
                                alt="ICP-MS" style="text-decoration:none;color:blue;">ICP-MS systems</a></li>
                    </ul>
                    </p>
                </article </section>
                <hr>
                <section class="main-section" id="ICM-MS_Sample_Preparation" style="clear:right;">
                    <header>ICP-MS Sample Preparation</header>
                    <article>
                        <p>
                            Inductively coupled plasma mass spectrometry (ICP-MS) is applicable to a wide variety of
                            sample types; therefore, it is used in many different industries.</p>
                        <p>To be processed efficiently in the plasma, samples must be in either gas or vapor (aerosol)
                            form. So, while gases can be analyzed directly by the plasma (e.g., when separated by gas
                            chromatography), solids and liquids have to be converted to aerosol form using either a
                            nebulizer (for liquids) or an ablation device (for solids).</p>
                    </article>
                </section>

                <section class="main-sections clearfix" id="ICP-MS_sample_processing">
                    <header class="subheader">ICP-MS sample processing</header>
                    <article>
                        <div class="flex-test">
                            <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-sample-preparation/jcr:content/MainParsys/image_e13b/foregroundimg.img.320.medium.jpg/1603737509951.jpg"
                                alt="ICP Nebulizer-introduction" class="icp-intro-image left">
                            <p> In most routine ICP-MS analyses, the sample is introduced as a liquid using a nebulizer
                                and spray chamber. The nebulizer uses supersonic expansion of gas to turn the liquid
                                into a fine mist, and the spray chamber then removes any droplets that are too large to
                                be processed in the plasma. This occurs at the sample interface of the instrument.</p>
                        </div </article>
                </section>

                <section class="main-sections" id="Liquid_ICP-MS_samples">
                    <header class="subheader" style="clear:right;">Liquid ICP-MS samples</header>
                    <article>
                        <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-sample-preparation/jcr:content/MainParsys/image_dbb9/foregroundimg.img.full.high.jpg/1603737510105.jpg"
                            alt="Auto-dilution of samples" class="icp-intro-image right">
                        <p>Liquid samples are typically digested and then reconstituted in an aqueous matrix to
                            stabilize elements as an ionic solution. The matrix typically contains 2% nitric acid, and
                            may have 0.5% hydrochloric acid added to stabilize certain elements. The final composition
                            of any matrix is highly dependent on the nature of the analytes being measured.</p>
                        <p>
                            Liquids can be analyzed directly without dissolution using a standard ICP-MS introduction
                            kit—provided the TDS (total dissolved solids) level is below ~0.5%. Above this level, the
                            TDS may precipitate in the nebulizer or overload the plasma, either of which alter the way
                            the sample is processed in the plasma. This can result in a data collection issue called
                            drift. Specialized nebulizers and spray chambers may be required to counteract drift; more
                            commonly, sample dilution is performed.

                            Organic liquid samples can be analyzed in the sample with minor modifications to the ICP-MS
                            system. Usually, a smaller injector and platinum tipped cones are used, and oxygen is added
                            to the plasma to prevent carbon deposition and signal drift.
                        </p>
                    </article>
                </section>

                <section class="main-sections" id="Solid_ICP-MS_samples">
                    <header class="subheader">Solid ICP-MS samples
                    </header>
                    <article>
                        <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-sample-preparation/jcr:content/MainParsys/image_cc8e.img.full.high.jpg/1603737510287.jpg"
                            alt="Sample digestion process" class="icp-intro-image left">
                        <p>With solid samples, digestion in strong and hot acids is the typical protocol. The acids
                            themselves range from simple nitric acid (for relatively simple matrices) to hydrofluoric
                            acid (for samples containing high silicon dioxide content). Samples containing organic
                            matter may also have hydrogen peroxide added to them during the digestion step because H2O2
                            breaks down organic matter efficiently.

                            Solid samples can also be directly turned into aerosols several different ways, the most
                            common being laser ablation (LA), spark ablation, or electrothermal vaporization (ETV). In
                            all of these methods, the samples are converted to an aerosol and transported to the plasma
                            with inert gas.
                        </p>
                        <p>
                            ETV is a bulk analysis method that interacts with the entire sample and is useful for
                            combustible samples. Spark ablation is a semi-bulk analysis tool and is useful for sampling
                            large spots (1–3 mm diameter) of a conducting sample. LA is a microanalysis technique using
                            high irradiance (UV) lasers to analyze very small spots (2–750 µm in diameter) on virtually
                            all solid samples. Because of the small spot sizes, LA is also useful for tracking element
                            distribution in a sample. </p>
                    </article>
                </section>

                <section class="main-sections" id="Other_considerations_during_ICP-MS">
                    <header class="subheader">Other considerations during ICP-MS</header>
                    <article>
                        <p>Internal standards can be added into the sample to monitor and correct for a range of
                            parameters during the experiment, from sample viscosity to analyte precipitation to
                            instrument drift.

                            The amount of dissolved solid in the sample also has an effect on the analysis. Typically,
                            the maximum percentage of total dissolved solid (TDS) that will allow robust data to be
                            produced is 0.2%, but this also depends on the instrument setup (nebulizer used, cones, and
                            interface setup) and the constituents of the matrix. Heavier elements have a much stronger
                            effect on the ion beam than lighter elements, so a 0.5% TDS for a sodium or calcium-based
                            matrix can be tolerated, whereas only 0.1% of a tungsten or lead-based matrix is possible.
                        </p>
                        <p>
                            Specialized sample introduction systems can be coupled to an ICP-MS, including spark- or
                            laser-ablation systems, hydride generators, and chromatography systems (GC, IC, HPLC, and
                            UPLC systems). In these cases, sample preparation protocols will vary depending on the
                            sample introduction system being used. </p>
                    </article>
                </section>
                <hr>
                <section class="main-section" id="ICP-MS_Data_Analysis">
                    <header>ICP-MS Data Analysis
                    </header>
                    <article>
                        <p>The goal of almost all ICP-MS analyses is to quantify trace elements within a sample. The
                            output of an ICP-MS is numerical, and usually provided in counts per second. For any
                            quantitative analysis, regardless of the technique, the instrument response is largely
                            meaningless without reference to a known value. </p>
                        <p>Calibration is the process of determining the instrument response for a known concentration
                            of analyte, and in doing so, enabling test sample concentrations to be quantified.
                        </p>
                        <p>
                            For this reason, almost all analyses include a set of calibration reference samples, or
                            ‘standards’. A range of standards is tested at the start of the analysis to generate a
                            ‘calibration curve.’ In this way, instrument response can be correlated to actual analyte
                            concentration within the samples. </p>
                    </article>
                </section>

                <section class="main-sections" id="Semi-quantitative_calibration">
                    <header class="subheader">Semi-quantitative calibration</header>
                    <article>
                        <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-data-analysis/jcr:content/MainParsys/image_78a9/foregroundimg.img.320.low.jpg/1603737392280.jpg"
                            alt="Semi-quatitative curve" class="icp-intro-image right">
                        <p>When complete precision is not required, and analyte standards are not readily available,
                            semi-quantitative calibration can be used to generate concentration data. Semi-quantitative
                            calibrations are typically based on the sensitivities of elements surrounding the analyte
                            signal, and the response from this range of elements is already known. These sensitivities
                            are corrected for isotope abundance and a curve is fitted to them. Sensitivity for the
                            analyte is then measured from that curve, and a concentration is calculated.
                        </p>
                        <p>
                            The response curve is usually a polynomial fit, and therefore requires at least three other
                            elements for effective semi-quantitative analysis to be performed. When elements with
                            similar masses to the analyte are used, semi-quantitative concentration data offer good
                            accuracy.
                        </p>
                    </article>
                </section>

                <section class="main-sections" id="External_calibration">
                    <header class="subheader">External calibration
                    </header>
                    <article>
                        <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-data-analysis/jcr:content/MainParsys/image_4230/foregroundimg.img.320.low.jpg/1603737392405.jpg"
                            alt="Calibration curve" class="icp-intro-image right">
                        <p>External calibration uses a range of separate (external) standards of known concentration of
                            the analyte to generate a calibration curve of instrument response. The calibration curve,
                            which is usually a linear regression, is then used to back-calculate the concentration of
                            analyte in unknown samples based on their instrument response.

                            Pure elemental standards generate highly accurate calibration curves; however, they do not
                            account for matrix-induced effects, such as signal suppression, or instrument drift that can
                            arise due to the matrix present in the sample.
                        </p>
                        <p>
                            Drift can be corrected by recalibrating throughout the assay, but this can add significant
                            time and expense to most routine assays. Matrix effects can be compensated for by using
                            matrix-matched calibration standards, which means adjusting the matrix of the standards to
                            match that of the samples. Accomplishing this task successfully depends entirely on how well
                            the sample matrix is understood and characterized.
                        </p>
                    </article>
                </section>

                <section class="main-sections" id="Internal_standardization">
                    <header class="subheader">Internal standardization
                    </header>
                    <article>
                        <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-data-analysis/jcr:content/MainParsys/image_6398/foregroundimg.img.320.low.jpg/1603737392531.jpg"
                            alt="Sample Number" class="icp-intro-image left">
                        <p>A good way to compensate for matrix effects and instrument drift is to combine external
                            calibration with internal standardization. This is the most widely used method of
                            calibration in ICP-MS and involves adding the same amount of one or more elements to all
                            measured solutions (blanks, calibration standards, quality control standards, unknown
                            samples, etc.). The response from this element is expected to be the same throughout the
                            assay, so that any variation is assumed to be derived from either matrix effects or
                            instrument drift. </p>
                        <p>
                            A mathematical correction factor is calculated from the relative internal standard response
                            that is then applied to the analytes to correct for both matrix and drift effects.
                            The ideal internal standard for any given analyte is not already present in the sample, has
                            a similar mass and ionization potential as the analyte, and behaves similarly to the
                            analyte, both in solution and the plasma.
                        </p>
                    </article>
                </section>

                <section class="main-sections" id="Method_of_standard_additions">
                    <header class="subheader">Method of standard additions</header>
                    <article>
                        <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-data-analysis/jcr:content/MainParsys/image_4211/foregroundimg.img.320.low.jpg/1603737392621.jpg"
                            alt="Concentration curve with external calibration standard" class="icp-intro-image left">
                        <p>In cases where the samples have a very high percentage of total dissolved solids (e.g., 0.3%
                            or higher), internal standardization may not be sufficient to correct for matrix-induced
                            effects and drift. The sample is then divided into several aliquots in order to generate a
                            calibration curve (e.g., three aliquots for a blank and two standards). Into each of these
                            aliquots, external calibration solutions are spiked directly. This yields an ‘offset’
                            calibration curve, and the negative x-intercept is the analyte concentration.
                        </p>
                        <p>
                            While the method of standard additions is more robust and reliable than typical calibration,
                            it is costly and time-consuming. Ideally, one might use just one sample to generate a
                            calibration curve, then use that curve to quantify many other samples, provided they all
                            have the same matrix.
                        </p>
                    </article>
                </section>
                <hr>
                <section class="main-section" id="ICP-MS_Systems_and_Technologies" style="clear:left;">
                    <header>ICP-MS Systems and Technologies
                    </header>
                    <article>
                        <header class="subheader" id="What_is_an_ICP-MS_system">What is an ICP-MS system?</header>

                        <p> <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-systems-technologies/jcr:content/MainParsys/image_de39/foregroundimg.img.320.low.jpg/1602527922123.jpg"
                                alt="ICP-MS decomposes" class="icp-intro-image right">An ICP-MS system comprises five
                            basic parts: the sample introduction system, plasma, vacuum interface, ion optics with mass
                            analyzer, and ion detection system. The sample introduction system and plasma are operated
                            at atmospheric pressure, whereas the ion optics, mass discrimination, and ion detection
                            areas are operated under high vacuum.

                        </p>

                        <p>The plasma is a mixture of ions, electrons, and atoms that, at atmospheric pressure, has an
                            extremely high temperature (up to 10,000 K). At these temperatures, most elements easily
                            make the transition from atoms to ions. A very useful characteristic of the argon plasma is
                            that most of the formed ions are single charged positive ions, so mass spectra are
                            relatively simple to generate and interpret.
                        </p>
                        <p>
                            ICP-MS Instrumentation is varied and the specific design is largely based on the type of
                            applications that the instrument is running. The plasma itself is sustained by a radio
                            frequency (RF) generator, which delivers energy using an induction coil or load coil.
                            Samples are ionized by the plasma and are transferred to the mass analyzer via a vacuum
                            interface. Once separated, ions are detected by the ICP-MS detection system for data
                            analysis by the operator. </p>
                    </article>
                </section>

                <section class="main-sections" id="Radio-frquency_RF_generator">
                    <header class="subheader">Radio-frequency (RF) generator
                    </header>
                    <article>
                        <p> <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-systems-technologies/jcr:content/MainParsys/image_f6ce/foregroundimg.img.320.medium.jpg/1602527922252.jpg"
                                alt="Different designs of RF Generator" class="icp-intro-image left">The radio frequency
                            (RF) generator provides a constant source of energy to maintain the plasma. It does this by
                            sending a high power (~1.5 kW) RF signal through a load coil wrapped around the ICP torch.
                            The plasma itself is formed when seed electrons from a spark source, such as a Tesla coil,
                            cause argon atoms to ionize within the torch gas flows. When these ions collide with other
                            argon atoms, they cause a cascade of ionization that forms the plasma. The constant RF
                            electrical energy provided by the RF generator then maintains the plasma.
                            The plasma itself generates a magnetic field that directly opposes the RF generator. For a
                            stable plasma, the RF generator and plasma frequencies are synchronized (or ‘matched’) so
                            the magnetic field coming from the plasma has minimal effect and the plasma can be sustained
                            more easily. When samples are introduced, the plasma frequency changes, so the RF generator
                            may become mismatched to the plasma.</p>
                        <p>
                            Due to this phenomenon, an RF generator must be capable of coping with fluctuations in the
                            plasma by either returning the plasma frequency to the RF generator frequency (performed in
                            frequency-locked generators), or by adjusting the RF generator frequency so that it matches
                            that of the plasma (performed in free-running generators). Free-running RF generators are
                            capable of coping with wider variations in the sample matrix as well, and can therefore
                            sustain the plasma for longer time periods. In so doing, they enable longer analyses because
                            a more robust plasma is possible.
                        </p>
                    </article>
                </section>

                <section class="main-sections" id="The_sample_interface">
                    <header class="subheader">The sample interface
                    </header>
                    <article>
                        <div class="flex-test">
                            <p>The sample interface is a crucial part of the ICP-MS, comprising a pair of water-cooled
                                cones that allow ions from the sample to enter the high vacuum region.

                                The sampler cone allows only the central channel of the plasma (where the sample ions
                                are formed) into the intermediate vacuum region. This material also undergoes supersonic
                                expansion so that ions are pulled into the high vacuum region through a skimmer cone,
                                with the aid of a negatively charged extraction lens that is located behind the cone.
                            </p>
                            <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-systems-technologies/jcr:content/MainParsys/image_daf5/foregroundimg.img.320.low.jpg/1602527922416.jpg"
                                alt="ICP-MS interface" class="icp-intro-image right">
                        </div>
                    </article>
                </section>

                <section class="main-sections" id="Mass_analyer" style="clear:left;">
                    <header class="subheader">Mass analyzer
                    </header>
                    <article>
                        <p>Once they pass through the high vacuum region, elemental masses of the sample are separated
                            using a mass analyzer.

                            There are two types of mass analyzer typically used in ICP-MS, namely quadrupole and
                            magnetic sector. Quadrupole mass analyzers are sequential, so each element is measured in
                            sequence. Magnetic sector analyzers can be either sequential or simultaneous depending on
                            the geometry of the instrument components.
                        </p>
                        <p>
                            Quadrupole instruments are typically used in routine labs since they are relatively easy to
                            operate and maintain. Magnetic sector instruments are inherently more sensitive than
                            quadrupole instruments because they use higher ion extraction potentials. As a result, they
                            are used in more specialized applications, or when higher sensitivity is needed. </p>
                    </article>
                </section>

                <section class="main-sections" id="Quadrupole_mass_analyzer">
                    <header class="subheader">Quadrupole mass analyzer
                    </header>
                    <article>
                        <p> <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-systems-technologies/jcr:content/MainParsys/image_e161/foregroundimg.img.full.high.jpg/1602527922546.jpg"
                                alt="Quadrupole mass analyzer" class="icp-intro-image left">A quadrupole mass analyzer
                            works by combining a radio frequency (RF) alternating current (AC) potential with a direct
                            current (DC) potential over four electrodes, or poles, to create the electric field that
                            sample ions pass through. As the ions pass through this electric field, they gain energy and
                            accelerate.
                            Two of the oppositely placed poles have a positive potential applied to them, and the other
                            two have a negative potential applied. So, the quadrupole actually generates two overlapping
                            electric fields: one in the horizontal plane and the other in the vertical plane.</p>
                        <p>
                            The DC component of the electric field produces a constant force on the ions while they
                            travel through the quadrupole. Because the ions are positively charged from the plasma, the
                            positive poles repel the ions into the center of the mass analyzer, while the negative poles
                            attract the ions away from the center of the quadrupole.

                            The AC component counteracts the effect of the DC component depending on the ion’s mass.
                            Because the ions gain energy as they pass through the quadrupole, the degree to which the AC
                            component affects the ion flight path increases along the length of the quadrupole.
                        </p>
                        <p><img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-systems-technologies/jcr:content/MainParsys/image_8292/foregroundimg.img.full.high.jpg/1602527922667.jpg"
                                alt="Stability diagram" class="icp-intro-image right">
                            Lighter ions are more easily affected by the AC field than heavier ions and they follow the
                            oscillations of the RF driving circuit. Heavier ions are significantly less responsive to
                            the AC field, tending to follow the DC field instead. This means that for the positive pair
                            of poles, lighter ions are pushed out of the quadrupole along its length by oscillations.
                            For the negative pair of poles, the lighter ions are held in the quadrupole by oscillations
                        </p>

                        <p>For both the vertical and horizontal electric fields, only specific combinations of AC and DC
                            potential result in a stable flight path through the quadrupole for any given mass. Plotted
                            on a stability diagram, there is overlap in the stability regions, so the ion can pass
                            through the quadrupole mass filter.
                        </p>
                        <p>
                            The size of this stability region is different for each ion mass, so individual masses can
                            be resolved with specific AC/DC potential combinations. Mass resolution is controlled by the
                            ratio of DC against AC potential, and unit mass resolution is easily achieved. Keeping the
                            ratio constant and increasing the potentials allows each mass in the spectrum to be scanned
                            individually.</p>
                        <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-systems-technologies/jcr:content/MainParsys/image_9bb7/foregroundimg.img.320.low.jpg/1602527922728.jpg"
                            alt="Sifting" class="icp-intro-image center">

                        <p>Mass resolution can be controlled by increasing the DC offset of this line, but this does
                            come with an associated loss in sensitivity. Also, the practical resolution limit depends on
                            the overall sensitivity of the instrument. Typically, this is 0.7–0.85u in ‘normal’
                            resolution. However, in most quadrupole mass spectrometers, resolution can be switched to
                            ‘high’ resolution at 0.3–0.4u. Such a switch helps attenuate very high signals of, for
                            example, matrix components.
                        </p>
                    </article>
                </section>

                <section class="main-sections" id="Magnetic_sector_mass_analyzer">
                    <header class="subheader">Magnetic sector mass analyzer</header>
                    <article>

                        <p> <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-systems-technologies/jcr:content/MainParsys/image_2799/foregroundimg.img.full.high.jpg/1602527922829.jpg"
                                alt="ESA" class="icp-intro-image left">A magnetic sector mass analyzer works by applying
                            a force on charged ions as they pass through a magnetic field. This force is perpendicular
                            to the ion flight path and is directly proportional to the momentum of the ions. As such,
                            the ions are deflected, with the radius of their deflection proportional to the force being
                            applied as well as the momentum of those ions.
                        </p>
                        <p>
                            The electromagnets used in mass spectrometers are also curved and contain a central channel
                            through which particular ions can pass unhindered. Varying the magnetic field strength
                            ultimately controls the momentum of the ion that can pass through the center of the
                            electromagnet, and into the following section of the mass spectrometer.
                        </p>
                        <p>
                            Momentum is the product of an ion’s mass and velocity, which is in turn governed by the
                            amount of kinetic energy it contains. Because a plasma produces ions with a wide range of
                            kinetic energies, ions of slightly varying mass could have the same momentum. It is
                            therefore possible for two ions of different mass to have the same radius of curvature
                            through the magnet.
                        </p>
                        <p><img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-systems-technologies/jcr:content/MainParsys/image_f306/foregroundimg.img.320.low.jpg/1602527922893.jpg"
                                alt="Inside an ESA" class="icp-intro-image right">
                            To compensate for this effect, an electric sector analyzer (ESA) is used to separate ions by
                            their kinetic energy. The ESA focuses ions of the same mass yet slightly varying kinetic
                            energies onto the same point in space, so that any remaining ions of slightly varying mass
                            can be rejected from the ion beam.
                        </p>

                        <p> <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-systems-technologies/jcr:content/MainParsys/image_dc68/foregroundimg.img.320.low.jpg/1602527922949.jpg"
                                alt="an ESA in the schematic of a multicollector ICP-MS system"
                                class="icp-intro-image left">Correcting ion energies allows the magnetic sector to
                            separate ions into different points in space. Placing separate detectors at these points
                            allows ions to be detected simultaneously, and these so-called ‘multicollector’ systems are
                            capable of measuring isotope ratios with much greater precision than can be achieved with
                            sequential quadrupole or magnetic sector mass analyzers. In this case, the ESA and magnet
                            are reversed to provide better spatial resolution and stability.</p>

                    </article>
                </section>

                <section class="main-sections" id="Coping_with_interferences" style="clear:left;">
                    <header class="subheader">Coping with interferences
                    </header>
                    <article>
                        <!-- table in html 
          <img src="" alt="" class="icp-intro-image">-->
                        <p>Some analytes have other elements or polyatomic species that overlap with their signal,
                            resulting in the analyte signal becoming higher than normal. These species are called
                            interferences. One type of interference occurs when argon, sample matrix, and solvent-based
                            ions enter the collision cell and generate new product ions. These product ions can affect
                            data quality by reducing detection capability.
                        </p>
                        <p>
                            Interferences must be corrected if the final analyte signal is to be accurate. This is
                            completed either during the analysis or following data acquisition.

                            Reducing interferences is a key challenge in ICP-MS, but it can be achieved in several ways.
                            One of the simplest methods is using alternative sample introduction, including aerosol
                            desolvation, to minimize the population of unwanted precursor ions in the plasma itself.
                            This serves to reduce molecular species entering the mass spectrometer. Cold plasma
                            techniques take this effect into account; in plasma generation, the plasma power is reduced,
                            which also reduces the formation of polyatomic species. This method, however, assumes
                            consistent matrix effects; any significant changes in matrix from one sample to the next
                            could have a significant effect on interference generation that cannot be accounted for by
                            internal standardization.
                        </p>
                        <p>
                            Isobaric interferences can be addressed by measuring another intereference isotope and,
                            after correcting for natural isotope abundance differences, using those counts to estimate
                            the proportion of signal in the analyte channel that is derived from the interference. This
                            can then be subtracted before further data processing to give a more accurate result. This
                            method assumes no isotope fractionation, so it cannot be used for isotope dilution or any
                            method intended for geological process analysis. </p>
                    </article>
                </section>

                <section class="main-sections" id="Collision_reaction_cell_technology">
                    <header class="subheader">Collision reaction cell technology
                    </header>
                    <article>

                        <p> <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-systems-technologies/jcr:content/MainParsys/image_cf1e/foregroundimg.img.320.low.jpg/1602527923260.jpg"
                                alt="a quadrupole CRC" class="icp-intro-image right">The methods mentioned above are not
                            always successful in addressing interferences; therefore, collision reaction cell (CRC)
                            technology has emerged as a comprehensive solution to this issue. In CRC, the cell is a
                            multipole system like the mass analyzer, but only operates with RF voltage. This means it
                            can transmit a range of masses, but each ion mass has an optimum transmission at a different
                            AC voltage.
                        </p>
                        <p>
                            In quadrupole CRCs, there is a minimum mass that will pass through the cell, or a ‘low mass
                            cutoff’ (LMCO), that is tunable with AC voltage. An AC voltage for optimum transmission of
                            the analyte mass is selected (i.e., final mass analyzer mass), which means quadrupole CRCs
                            have the added advantage of being able to reject small ‘precursor’ ions and reduce
                            polyatomic ion formation in the cell itself. This inherently reduces interferences by
                            design, even when not in active use.

                            The CRC can be set to kinetic energy discrimination (KED) mode, which is the most universal
                            mode for interference removal. This mode utilizes helium as the cell gas because it is inert
                            and does not react with the analyte. Helium also has low mass, so it does not degrade signal
                            sensitivity very much.
                        </p>
                        <p>
                            KED creates a potential energy barrier at the CRC exit using ion lenses. Because the exit of
                            the CRC is more positive than the entrance, this slightly repels ions back into the cell. As
                            the sample ions pass through the CRC, they encounter neutral helium atoms and collide. These
                            collisions slow the ions down, so their kinetic energy is reduced. As the ions progress
                            through the cell and collide with additional upstream helium atoms, their kinetic energy is
                            reduced to the point where the potential energy barrier prevents them from leaving the cell
                            as part of the ion beam, resulting in their ejection from the cell.
                        </p>
                        <p><img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-systems-technologies/jcr:content/MainParsys/image_a512/foregroundimg.img.320.low.jpg/1602527923334.jpg"
                                alt="CRD in KED mode" class="icp-intro-image left">
                            Polyatomic ions are larger than sample ions because they are made up of multiple atoms by
                            definition. Because of this, they encounter more collisions than the analyte ions, and so
                            lose energy faster. By altering the amount of helium in the cell, it is possible to reduce
                            the kinetic energy of the polyatomic interferences to the point where they are ejected by
                            the potential energy barrier set up in the cell, but not the analyte ion.
                        </p>

                        <p>When combined with KED, the LMCO collision/reaction cell is capable of filtering out unwanted
                            polyatomic interferences based on differences in analyte and polyatomic intererence
                            cross-sectional sizes. Such “Q Cell” technology effectively removes unwanted precursor ions,
                            preventing them from recombining later on in the selection quadrupole.

                        </p>
                    </article>
                </section>

                <section class="main-sections" id="Ion_detection" style="clear:left;">
                    <header class="subheader">Ion detection
                    </header>
                    <article>

                        <p>After mass separation, ions must be detected and amplified in order to determine their
                            intensities. Two types of detector are typically used: Faraday cups and electron
                            multipliers. <img
                                src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-systems-technologies/jcr:content/MainParsys/image_76a6/foregroundimg.img.320.low.jpg/1602527923451.jpg"
                                alt="Basic schematic of a Faraday cup" class="icp-intro-image right">
                        </p>
                        <p>
                            Faraday cups are simple devices: When high-velocity ions hit the Faraday cup, they transfer
                            their charge to the metal inside the cup. This induces a current that is sent to an
                            amplifier circuit leading to detection. Faraday cups require a relatively large number of
                            ions to produce a measurable signal, and so cannot be used to detect single ion events.
                            However, they are extremely stable and are suited to precision isotope ratio measurements,
                            especially in multicollector instruments where the necessary ion currents are easily
                            achievable. </p>

                        <p> <img src="https://www.thermofisher.com/fi/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/trace-elemental-analysis-tea-information/inductively-coupled-plasma-mass-spectrometry-icp-ms-information/icp-ms-systems-technologies/jcr:content/MainParsys/image_6172/foregroundimg.img.full.high.jpg/1602527923516.jpg"
                                alt="Basic schematic of an electron multiplier" class="icp-intro-image left">
                            Electron multipliers (also known as secondary electron multiplier, or SEM, detectors) can
                            detect extremely small ion currents, including even single ions, coming from the mass
                            analyzer. They operate on the principle of secondary electron emission, in which charged
                            particles with sufficient energy incident on a ‘dynode’ stimulate the emission of electrons
                            from the surface.

                            By setting up a series of discrete dynodes, gain amplification that allows for single ion
                            detection can be easily achieved. Modern SEM detectors are capable of count rates in the
                            range of single ions, to more than 109 ions per second.</p>
                    </article>
                </section>

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