📚 Combined Analytical Techniques: Mass Spectrometry, IR and NMR for Edexcel A-Level Chemistry | 综合分析技术：质谱、红外与核磁共振（Edexcel A-Level 化学）
In Edexcel A-Level Chemistry, modern analytical techniques are not normally used in isolation. A single spectrum rarely proves a structure on its own. Instead, exam questions expect you to combine evidence from mass spectrometry (MS), infrared spectroscopy (IR) and proton NMR (¹H NMR) to identify an unknown organic compound. This revision guide explains how each technique works, what it tells you, and how to build a confident structural answer.
在 Edexcel A-Level 化学中，现代分析技术通常不会单独使用。仅凭一张谱图很少能直接证明结构。考试题要求你综合质谱（MS）、红外光谱（IR）和质子核磁共振（¹H NMR）的证据来鉴定未知有机化合物。本复习指南将说明每种技术的原理、它能提供的信息，以及如何自信地推导结构答案。
1. Why Combined Techniques Are Essential | 为什么综合技术至关重要
A single technique only gives one piece of the puzzle. Mass spectrometry gives molecular mass and fragments, IR identifies functional groups, and NMR shows the chemical environment of hydrogen atoms. Together they can confirm a full structural formula. This combined approach is central to Edexcel organic analysis questions.
单一技术只能提供拼图的一块。质谱给出分子质量和碎片，红外光谱识别官能团，核磁共振显示氢原子的化学环境。三者结合才能确认完整的结构式。这种综合方法是 Edexcel 有机分析题的核心。
2. Mass Spectrometry: Finding the Molecular Ion | 质谱：确定分子离子
olecular formula. For example, propan-1-ol, C₃H₈O, has Mᵣ = 60, so M⁺ appears at m/z = 60.
在质谱中，分子离子峰 M⁺ 通常是最高质荷比 m/z 中对应于整个分子的峰（忽略同位素峰）。对于有机化合物，M⁺ 的 m/z 给出相对分子质量 Mᵣ。在高分辨率质谱中，精确质量可给出分子式。例如，丙-1-醇 C₃H₈O 的 Mᵣ = 60，因此 M⁺ 出现在 m/z = 60。
m/z of M⁺ = relative molecular mass Mᵣ
M⁺ 的 m/z = 相对分子质量 Mᵣ
3. Fragmentation Patterns and Structural Clues | 碎片模式与结构线索
gests an ethyl fragment C₂H₅⁺. Use fragments only as supporting evidence, not as proof on their own.
碎片化会使分子离子断裂成较小的带正电荷碎片。这些峰有助于识别存在的烷基或官能团。例如，m/z = 29 的峰通常提示乙基碎片 C₂H₅⁺。碎片只能作为辅助证据，不能单独作为证明。
4. Infrared Spectroscopy: Functional Group Detection | 红外光谱：官能团检测
IR radiation causes bonds to stretch and bend. Different bonds absorb at characteristic frequencies, measured in wavenumbers (cm⁻¹). The presence or absence of key absorptions confirms functional groups. For example, a broad O-H absorption at 2500-3550 cm⁻¹ suggests an alcohol or carboxylic acid.
红外辐射使化学键发生伸缩和弯曲振动。不同的键在特定频率处吸收，以波数（cm⁻¹）表示。关键吸收峰的存在或缺失可以确认官能团。例如，2500-3550 cm⁻¹ 处的宽 O-H 吸收提示醇或羧酸。
5. Key IR Absorption Bands | 红外关键吸收带
The table below summarises the main infrared absorptions you need to recognise in Edexcel A-Level Chemistry. Always quote ranges, not a single fixed value, unless
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