协作头脑风暴
brainstorming
在实现前澄清需求、探索设计选择,并形成清晰的开发方向。
develop-hplc-method【开发与工程】Develop a high-performance liquid chromatography method: define separation goals, select column chemistry and mobile phase, optimize gradient and flow conditions, choose the appropriate detector, and evaluate initial method performance for target analytes in solution or complex matrices.
独立 GitHub 快照 · 自动分类 · 以原作者文档为准
系建高效液相層析法:模擇、柱化、流相與梯設、流與溫優、檢擇、迭代改進,為非揮、熱不穩、或極性分析物於液或複基質。
得:規格書,列分析物及物化性、基質述、效標、等度 vs 梯決。
敗:pKa 或 logP 未知→由結構以工具(ChemAxon、ACD/Labs)估,或於 C18 柱 pH 3、7 運探梯以驗留行。
依分析物性擇層析模與柱。
| Mode | Column Chemistry | Mobile Phase | Best For |
|---|---|---|---|
| Reversed-phase (RP) | C18 (ODS) | Water/ACN or water/MeOH + acid/buffer | Non-polar to moderately polar, most small molecules |
| RP (extended) | C8, phenyl-hexyl, biphenyl | Water/organic + modifier | Shape selectivity, aromatic compounds, positional isomers |
| RP (polar-embedded) | Amide-C18, polar-endcapped C18 | Water/organic, compatible with high aqueous | Polar analytes that elute too early on standard C18 |
| HILIC | Bare silica, amide, zwitterionic | High organic (80-95% ACN) + aqueous buffer | Very polar, hydrophilic compounds (sugars, amino acids, nucleotides) |
| Ion-exchange (IEX) | SAX or SCX | Buffer with ionic strength gradient | Permanently charged species, proteins, oligonucleotides |
| Size-exclusion (SEC) | Diol-bonded silica, polymer | Isocratic aqueous or organic buffer | Protein aggregates, polymers, molecular weight distribution |
| Chiral | Polysaccharide (amylose/cellulose) | Normal-phase or polar organic mode | Enantiomeric separations, chiral purity |
得:柱化、尺、粒徑已擇並由分析物性證。
敗:初探於 C18 留差→換更留之相(芳香→phenyl-hexyl)或異模(極性→HILIC)。
得:流相組(有機、水、緩/添、pH)及梯廓已定,探行確認析物洗脫於程窗內。
敗:選擇差(梯優後仍共洗脫)→換有機(ACN 與 MeOH 互換)、調 pH 2 單位、或為荷析物加離子對試。
得:流率與柱溫已優,背壓在限內,分辨維持或勝初條件。
敗:背壓過高→減流、增溫、或換寬徑或大粒柱。高溫降分辨→返 30 C 受較長運時。
| Detector | Principle | Sensitivity | Selectivity | Key Considerations |
|---|---|---|---|---|
| UV (single wavelength) | Absorbance at fixed lambda | ng range | Compounds with chromophores | Simple, robust, most common |
| DAD (diode array) | Full UV-Vis spectrum | ng range | Chromophores + spectral ID | Peak purity assessment, library matching |
| Fluorescence (FLD) | Excitation/emission | pg range (10-100x more sensitive than UV) | Native fluorophores or derivatized | Excellent selectivity, requires fluorescent analytes |
| Refractive index (RI) | Bulk property | ug range | Universal (no chromophore needed) | Temperature-sensitive, gradient-incompatible |
| Evaporative light scattering (ELSD) | Nebulization + light scattering | ng range | Universal, non-volatile analytes | Semi-quantitative, non-linear response |
| Charged aerosol (CAD) | Nebulization + corona discharge | ng range | Universal, non-volatile analytes | More uniform response than ELSD |
| Mass spectrometry (MS) | m/z detection | pg-fg range | Structural, highest selectivity | Requires MS-compatible mobile phases |
得:檢已擇並設(波、增益、取率)合析物化學與靈敏。
敗:UV 靈敏不足於所需 LOQ→考螢光衍生(胺用 OPA、胺酸用 FMOC)或換 LC-MS/MS 為最高靈敏選擇。
得:諸系統適用標過;法分目析物與基質干擾及已知降解;參已書以轉。
敗:迭調不能解→考根本異策(換層析模、2D-LC、或衍生)並返步二。
develop-gc-methodinterpret-chromatogramtroubleshoot-separationvalidate-analytical-method