Name: icp-ms signal interference sources and fixes
Uploaded: 2024-04-04T10:51:35.000Z
Duration: 1 min 20 s
Channel: JoVE

ICP-MSの利点にもかかわらず、正確な元素分析は分光干渉と非分光干渉の影響を受けます。
分光干渉は、分析対象物イオンと同じm/z値を持つイオンによって引き起こされます。干渉種には、同重体種、多原子イオン、および難治性酸化物イオンが含まれます。
アイソバリック干渉は、同じ質量数を持つ異なる核種である分析種のアイソバーから生じます。これは、m/zの値が同じであることを意味します。
多原子イオン干渉は、プラズマ種とマトリックスまたは大気種が組み合わさって多原子種を形成し、さらに分析対象物と同じm/z値の分子イオンに分裂することに起因します。
分析種およびマトリックス種から難治性酸化物および水酸化物種が形成されるため、重大な干渉が生じます。 
非分光干渉には、高濃度のマトリックス分子種に関連し、一般に分析種のシグナル減少を引き起こすマトリックス効果が含まれます。
マトリックス効果は、適切な内部標準を使用することで大幅に補正できます。

誘導結合プラズマ質量分析 (icp-ms): 干渉

Inductively Coupled Plasma-Mass Spectrometry (ICP-MS): Interferences

誘導結合プラズマ質量分析法 (ICP-MS) は、正確な元素分析のための選択性と感度が高い技術です。 ICP-MS 質量スペクトルはの分析は比較的簡単ですが、分光的および非分光的干渉の影響を受けます。分光干渉は、分析対象イオンと同じ m/z 値を持つイオン種がプラズマに含まれる場合に発生します。分光干渉は、等重イオン、多原子イオン、および耐火性酸化物イオン干渉に分類できます。

等重干渉は、誘導結合プラズマに等重種の分析物が含まれる場合に発生します。これらの種は同じ質量数を持つ異なる核種であるため、同じ電荷を仮定すると分析対象物と同じ m/z 値を持ちます。たとえば、40Ar+ と 58Fe+ は通常、それぞれ 40Ca+ と 58Ni+ のピークと重なります。分解能が 1 u 未満の四重極ベースの質量計器は、等圧干渉の影響を大きく受けます。ただし、より高解像度の機器を使用すると、この影響を最小限に抑えることができます。

さまざまな血漿成分がマトリックスまたは大気成分と相互作用して多原子種を形成するときに、別の分光干渉が観察されます。多原子種はさらに断片化されて分析対象イオンと同じ m/z 値を持つ分子イオンを形成する可能性があります。 40ArH+、16O2+、および 40ArO+ は、潜在的な干渉物質の一部です。ブランク補正または別の分析対象同位体を使用すると、このような干渉が除去されます。

別の重大な干渉は、いくつかの分析物およびマトリックス成分が酸化物および水酸化物を形成し、そのピークが分析物イオンと重なるときに発生します。酸化物と水酸化物の形成は、インジェクター流量、サンプルオリフィスサイズ、サンプラースキマー間隔などのさまざまな実験要因に依存します。これらの干渉は、等重イオンや多原子イオンの干渉よりも除去するのがより困難です。

非分光的干渉には主にマトリックス効果が含まれます。これは、高濃度のマトリックス種 (一般に 500 ～ 1000 mg/mL) に関連しており、分析対象物のシグナル低下を引き起こします。特定の実験条件により、分析対象物のシグナルが強化されます。マトリックス干渉は、検体の近くに質量およびイオン化ポテンシャルを持つ内部標準を組み込むことによって排除できます。

誘導結合プラズマ質量分析 (ICP-MS): 干渉

ICP-MSの利点にもかかわらず、正確な元素分析は分光干渉と非分光干渉の影響を受けます。
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inductively-coupled-plasma-mass-spectrometry-icp-ms-interferences

Education

JoVE Core

Analytical Chemistry

分析化学

Unit 1

ユニット1

Principles of Mass Spectrometry

質量分析法の原理

KEY TERMS AND CONCEPTS

主要用語と概念

icp-ms signal interference sources and fixes

Inductively coupled plasma-mass spectrometry (ICP-MS) is a sensitive method for elemental analysis, but its spectra can be affected by interferences. These interferences can make the mass signal less accurate, even when the instrument is working well.

Spectroscopic interferences happen when ions in the plasma have the same mass-to-charge ratio, or m/z, as the analyte ion. This group includes isobaric interferences, polyatomic ion interferences, and refractory oxide ion interferences. Isobaric interference occurs when different nuclides share the same mass number and therefore the same m/z value if the charge is the same. For example, 40 Ar+ can overlap with 40 Ca+, and 58 Fe+ can overlap with 58 Ni+.

Quadrupole-based mass instruments, which have a resolution of less than 1 u, are strongly affected by isobaric interference. Using a higher-resolution instrument can help reduce this problem. Polyatomic interferences can appear when plasma species react with matrix or atmospheric components to form molecular ions. Examples include 40 ArH+, 16 O2+, and 40 ArO+.

These polyatomic interferences can be reduced with a blank correction or by choosing a different analyte isotope. Another important spectroscopic problem is the formation of oxides and hydroxides. These peaks can overlap with analyte ions. Their formation depends on experimental conditions such as injector flow rate, sample orifice size, and sampler-skimmer spacing. These interferences are often harder to remove than isobaric and polyatomic interferences.

Non-spectroscopic interferences mainly involve the matrix effect. A matrix is the other material in the sample, and a high matrix concentration of about 500 to 1000 mg/mL can reduce the analyte signal. Certain experimental conditions can improve the analyte signal. Matrix interference can also be reduced by using an internal standard with a mass and ionization potential close to the analyte.

ICP-MS Signal Interference Sources and Fixes

icp-ms-signal-interference-sources-and-fixes

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inductively coupled plasma-mass spectrometry (icp-ms): interferences

Inductively coupled plasma-mass spectrometry (ICP-MS) is a sensitive method for elemental analysis, but its spectra can be affected by interferences. These interferences can make the mass signal less accurate, even when the instrument is working well. Spectroscopic interferences happen when ions in the plasma have the same mass-to-charge ratio, or m/z, as the analyte ion. This group includes isobaric interferences, polyatomic ion interferences, and refractory oxide ion interferences. Isobaric...

key terms and concepts

Learn how ICP-MS signals can be affected by isobaric, polyatomic, oxide, and matrix interferences, and how blank correction and internal standards help.

ICP-MS Signal Interference Sources and Fixes | JoVE K12

JoVE Core 分析化学 は、複雑な化学原理をアニメーションで視覚化することで、SI 単位から NMR 分光法を含むトピックをよりわかりやすくします。実験を撮影した実写動画では、これらの概念が世界中の研究所でどのように応用されているかを取り上げています。

analytical chemistry

ICP-MS Signal Interference Sources and Fixes

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