📚 How to Write Experimental Instructions: A Complete Lab Protocol Guide | 实验指导：实验室操作规程编写完全指南
Experimental instructions are the indispensable operating guide for any experiment. They give the experimenter detailed steps and methods so that the work proceeds smoothly and produces reliable results, and they play a central role in research, teaching and industrial testing alike.
实验指导是实验过程中不可或缺的操作指南，它为实验者提供详尽的操作步骤和方法，以保证实验顺利进行、获取可靠结果。在科研、教学和工业实验等众多领域，实验指导都发挥着核心作用。
This guide explains why a written protocol matters, how to write one step by step, and what principles keep it accurate, safe and easy to follow for every reader.
本文系统说明实验指导为何重要、如何一步步编写，以及用哪些原则能让它准确、安全、便于每一位读者执行。
1. What Is an Experimental Instruction? | 什么是实验指导
An experimental instruction, also called a lab protocol or a standard operating procedure (SOP), is a written, step-by-step document that tells the experimenter what to do, in what order, with which materials and apparatus, and how to judge whether the outcome is acceptable. A complete protocol normally contains six blocks: purpose, materials and apparatus, safety notes, procedure, data handling, and references.
实验指导又称实验方案、操作规程或 SOP，是一份书面的分步文件，明确告诉实验者做什么、按什么顺序做、使用哪些材料和器材，以及如何判断结果是否合格。一份完整的实验指导通常包含六个板块：实验目的、材料与器材、安全提示、操作步骤、数据处理和参考文献。
It should not be confused with a lab report. A protocol is written before the experiment and guides the operation; a report is written afterwards and records what was done and what was found. The protocol is the instruction manual, the report is the record.
它不应与实验报告混淆。实验指导写在实验之前，用于引导操作；实验报告写在实验之后，用于记录过程与结果。前者是操作说明书，后者是事实记录。
Typical users include undergraduate students in a teaching laboratory, research assistants repeating a published method, and technicians running a quality-control assay on a production line.
典型使用者包括教学实验室中的本科生、重复已发表方法的研究助理，以及在生产线执行质控检测的技术人员。
2. Why Experimental Instructions Matter | 为什么实验指导不可或缺
In research, a protocol is the backbone of reproducibility: another group should be able to repeat the work and obtain comparable data. In teaching, it protects students and shapes how quickly they master technique. In industry and clinical laboratories, documented SOPs are required by quality systems such as ISO/IEC 17025, GLP and GMP, and they are the first thing an auditor asks to see.
在科研中，实验指导是可重复性的支柱：其他课题组应能据此重复实验并获得可比数据。在教学中，它既保护学生安全，也决定他们掌握技术的速度。在工业和临床实验室，ISO/IEC 17025、GLP、GMP 等质量体系明确要求具备成文 SOP，它也是审核员最先索要的文件。
- Research: comparability of data across laboratories and over time. | 科研：跨实验室、跨时间的数据可比性。
- Teaching: safety, fairness and consistent assessment. | 教学：安全、公平与一致的评分标准。
- Industry: traceability, compliance and product quality. | 工业：可追溯性、合规性与产品质量。
- Publication: methods sections must be detailed enough to be repeated. | 发表：方法部分必须详细到可被重复。
3. Safeguarding Experimental Safety | 保障实验安全
Safety content is not an optional appendix. The instruction must include operating cautions, laboratory safety rules and requirements for using apparatus, so that the experimenter is protected at every stage. Risk assessment should be written down, not assumed.
安全内容不是可有可无的附录。指导中需要纳入操作注意事项、实验室安全规范及器材使用要求，全方位守护实验者的安全。风险评估应当写下来，而不是默认人人都懂。
| Hazard | 危害类别 | Typical Example | 典型例子 | Control Measure | 防护措施 |
| Chemical | 化学 | Concentrated acid, alkali | 浓酸、浓碱 | Gloves, goggles, fume hood | 手套、护目镜、通风橱 |
| Fire | 火灾 | Flammable solvents | 易燃溶剂 | No open flame, extinguisher nearby | 禁止明火、就近配备灭火器 |
| Biological | 生物 | Bacterial culture | 细菌培养 | Biosafety cabinet, autoclave | 生物安全柜、高压灭菌 |
| Thermal | 高温 | Muffle furnace, hot plate | 马弗炉、加热板 | Heat-proof gloves, clear bench | 隔热手套、清空台面 |
| Electrical | 电气 | Centrifuge, electrophoresis tank | 离心机、电泳槽 | Earthing, dry hands, no overload | 接地、手部干燥、不超载 |
A short emergency paragraph should state where the eyewash station, safety shower, first-aid kit and fire exit are, and whom to contact after a spill or injury.
还应有一段简短的应急说明，写明洗眼器、安全淋浴、急救箱和消防通道的位置，以及发生泄漏或受伤后的联系人。
4. Standardising Experimental Operations | 规范实验操作
The second function of a protocol is to give clear steps and methods so that everyone follows one unified workflow. Standardisation reduces the human variable: if two operators use the same volumes, temperatures and timings, their results become comparable.
实验指导的第二个功能是给出清晰的步骤和方法，让所有人遵循统一流程。标准化可以减少人为变量：如果两名操作者使用相同的体积、温度和时间，他们的结果就具有可比性。
Write each step in the imperative and quantify everything that can be quantified:
每一步都用祈使句书写，并把一切可以量化的内容量化：
- Volume and concentration: pipette 25.0 cm³ of 0.100 mol dm⁻³ HCl. | 体积与浓度：移取 25.0 cm³ 的 0.100 mol dm⁻³ 盐酸。
- Temperature and time: incubate at 37 °C for 30 ± 1 min. | 温度与时间：37 °C 孵育 30 ± 1 min。
- Apparatus setting: centrifuge at 3000 rpm for 10 min. | 仪器参数：3000 rpm 离心 10 min。
- Acceptance criteria: the titre must agree within 0.05 cm³. | 合格判据：两次滴定体积之差不超过 0.05 cm³。
Where a method comes from a published paper or a national standard, cite it and note any local modification.
若方法源自已发表论文或国家标准，应注明出处，并说明本实验室所做的任何改动。
5. Raising Experimental Efficiency | 提升实验效率
A well-structured instruction arranges the steps logically so that the experimenter completes the task efficiently and saves both time and resources. Good sequencing means fewer repeated weighings, less wasted reagent and shorter instrument queues.
合理编排的实验指导能让实验者高效完成任务，节省时间和资源。良好的顺序意味着更少的重复称量、更少的试剂浪费和更短的仪器排队时间。
Useful techniques include:
常用技巧包括：
- Batch preparation: weigh all samples before starting the first titration. | 批量准备：在第一次滴定前完成全部样品的称量。
- Parallel work: start the water bath while the standard solution equilibrates. | 并行操作：标准溶液恒温的同时开启水浴。
- Pre-labelled tubes and a printed data sheet to avoid transcription errors. | 预先贴好标签的试管与打印好的数据表，避免誊写错误。
- A realistic time estimate for each stage, including cleaning. | 为每个阶段（含清理）给出切实的时间估计。
总耗时 = 准备时间 + 操作时间 + 检测时间 + 清理时间
+ measurement + clean-up. Publishing this estimate prevents students from rushing the final stage.
把总耗时写进指导，可以避免学生在最后阶段仓促赶工。
6. Obtaining Accurate Results | 准确获取结果
The protocol should also explain how to read the outcome and how to process the data, so that after the experiment the results can be collected and analysed precisely. Results sections must distinguish raw readings from calculated values.
指导还应说明如何解读结果、如何处理数据，便于实验结束后精准采集并分析实验数据。结果部分必须区分原始读数与计算值。
Accuracy is judged against a reference value, and precision against repeated measurements:
准确度对照参考值判断，精密度则通过重复测量判断：
相对误差 = (|测量值 − 真值| ÷ 真值) × 100%
s = √( Σ(xᵢ − x̄)² ÷ (n − 1) )
curve) and the rule for rejecting an outlier. Never let the reader invent these criteria.
应写明必需的重复次数、空白与对照样品、校准要求（例如标准曲线 R² ≥ 0.990）以及异常值的剔除规则，不要让读者自己去猜。
7. Defining the Experimental Purpose | 明确实验目的
Start by stating the aim plainly, so the experimenter knows what the expected result looks like. A good aim sentence names the system studied, the variable measured and the technique used.
开宗明义地阐明实验目标，让实验者对预期结果心中有数。一句好的目的句应说明研究对象、测量变量和使用技术。
Example: To determine the concentration of ethanoic acid in a commercial vinegar sample by titration with standard sodium hydroxide solution.
示例：用标准氢氧化钠溶液滴定法测定市售食醋中乙酸的浓度。
Add the hypothesis if there is one, and define the variables explicitly:
若有假设也应写入，并明确定义变量：
- Independent variable: the factor deliberately changed. | 自变量：人为改变的变量。
- Dependent variable: the factor measured. | 因变量：被测量的变量。
- Control variables: temperature, pH, concentration, operator. | 控制变量：温度、pH、浓度、操作者。
An unclear aim is the most common reason a protocol is abandoned halfway through.
目的不清，是实验指导被中途弃用的最常见原因。
8. Detailing the Procedure | 细化实验步骤
Provide a detailed workflow covering preparation before the experiment, the core operation, and the tidy-up afterwards. Each step should begin with an action verb and describe one operation only.
提供详细的操作流程，包括前期准备、核心操作以及结束后的整理工作。每一步应以动词开头，且只描述一个操作。
| Stage | 阶段 | Content | 内容 | Output | 产出 |
| Preparation | 前期准备 | Apparatus list, reagent preparation, calibration | 器材清单、试剂配制、仪器校准 | Ready bench and labelled solutions | 就绪的台面与标签溶液 |
| Core operation | 核心操作 | Numbered steps with quantities and timings | 含用量与时间的编号步骤 | Raw readings | 原始读数 |
| Clean-up | 结束整理 | Waste disposal, glassware washing, instrument shutdown | 废弃物处理、器皿清洗、仪器关闭 | Safe bench, archived records | 安全台面、归档记录 |
Number the steps continuously. Use a flow diagram where a decision is needed, for example if the indicator colour changes before the expected volume.
步骤应连续编号。需要判断时可用流程图，例如指示剂在预期体积之前就变色时应如何处理。
9. Listing Key Precautions | 列出注意事项
Precautions point out the critical details of the experiment, such as apparatus handling rules and safety points, so that the process runs without mishap.
注意事项点明实验中需要留意的关键点，如器材使用规范和操作安全要点，确保过程万无一失。
- Never pipette by mouth; always use a filler. | 严禁用口移液，必须使用移液器或洗耳球。
- Rinse the burette with the titrant before filling. | 装液前先用滴定液润洗滴定管。
- Read the meniscus at eye level to avoid parallax error. | 视线与液面凹面最低点齐平读数，避免视差。
- Do not fill a crucible more than two-thirds full. | 坩埚装填不得超过容积的三分之二。
- Record the room temperature and pressure. | 记录室温与大气压。
Precautions are most useful when they explain why, not only what: a reason converts a rule into a habit.
说明原因比只下命令更有效：讲清道理，规则才能变成习惯。
10. Specifying Data Processing Methods | 给出数据处理方法
The instruction should give concrete practice for interpreting results and for statistical analysis, helping the experimenter handle data correctly. Specify the table format, the units and the number of significant figures before the experiment begins.
指导应提供结果解读和统计分析的具体做法，帮助实验者正确处理数据。在实验开始之前，就应规定表格格式、单位与有效数字位数。
Cover at least the following:
至少应涵盖以下内容：
- Raw data table with headings, units and uncertainty. | 含表头、单位与不确定度的原始数据表。
- Calculated quantities, with the working shown for one sample. | 计算量，并给出一个样品的完整计算过程。
- Graph requirements: axis labels, best-fit line, equation. | 作图要求：坐标轴标签、最佳拟合线、方程。
- Statistics: mean, standard deviation, confidence interval, t-test, regression. | 统计：平均值、标准偏差、置信区间、t 检验、回归。
- Outlier policy and rounding rules. | 异常值处理规定与修约规则。
c = n ÷ V （n 为物质的量，V 为体积）
of C₁V₁ = C₂V₂ and require them to verify the calibration curve before measuring unknowns.
对于稀释系列，应提醒读者使用 C₁V₁ = C₂V₂，并要求在测定未知样之前先验证标准曲线。
11. Providing References | 提供参考文献
Attach the relevant literature and further reading so the experimenter can understand the background and principles of the experiment in depth. References also let a supervisor check that the method is current.
附上相关文献和拓展阅读资料，方便实验者深入理解实验背景与原理。参考文献也能让指导教师核查方法是否仍属现行做法。
A practical reference list includes:
一份实用的参考文献清单包括：
- The original research paper or textbook method. | 原始研究论文或教科书方法。
- Reagent specification sheets and safety data sheets (SDS). | 试剂规格说明书与安全数据表（SDS）。
- Instrument manuals for the centrifuge, spectrophotometer or balance. | 离心机、分光光度计或天平的仪器手册。
- National or international standards such as ISO, ASTM or GB. | ISO、ASTM、GB 等国家或国际标准。
Cite consistently, for example in a numbered style, and give the edition, year and page range so the source can be found quickly.
引用格式应统一，例如采用顺序编码制，并给出版本、年份与页码，方便快速查找。
12. Writing Principles and Continuous Improvement | 编写原则与持续修订
Four principles govern the writing itself.
编写本身需要遵循四条原则。
- Concise | 简明扼要：keep the language tight, avoid long narrative, and let the reader grasp the essentials quickly. | 语言精炼，避免冗长叙述，让实验者迅速抓住操作要领。
- Clear | 清晰明了：design the layout so that steps, precautions and result analysis are easy to see and read. | 排版设计清晰，使步骤、注意事项和结果分析等内容一目了然，便于阅读和理解。
- Practical | 实践性强：use worked examples to illustrate steps and methods, strengthening hands-on skill. | 多使用实例来说明步骤与方法，强化实验者的实际操作技能。
- Communicative | 交流沟通：stay in dialogue with the experimenter, learn their difficulties and needs, and revise the content continuously. | 与实验者保持互动和反馈，及时了解困惑与需求，持续修订优化内容。
Practical revision habits make these principles real: give every version a number and a date, keep a change log, ask the first-time user to mark every step that caused hesitation, and review the protocol after each laboratory cycle. Check the six essential blocks - purpose, materials, safety, procedure, data handling and references - before every release.
让原则落地需要可操作的修订习惯：为每个版本编号并标注日期、保留修订记录、请首次使用者标出所有让他犹豫的步骤，并在每轮实验结束后复盘。发布前逐一核对六个必备板块——目的、材料、安全、步骤、数据处理和参考文献。
In short, experimental instructions are vital to the success of an experiment and to the accuracy of its results. When writing them, define the purpose clearly, detail the steps carefully, and keep the language concise and readable, so that both efficiency and accuracy improve. Continuous revision and refinement is itself an important route to higher experimental quality.
总之，实验指导对实验的成功和结果的准确至关重要。编写时，要明确目的、细化步骤，并注重简练清晰的表达，以提升实验的效率与准确性。同时，不断修订和完善指导内容，也是提高实验质量的重要途径。
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