工作场所空气中甲醛分光光度法验证方案
方案编号：
签名 日期 方案执行日期： 年 月 日 签名： 起草人 审核人 批准人
ZQ ZQ（J）-YZ-2017-2012
目 录
1. 概述 ········································································································ 1 2. 目的 ········································································································ 1 3. 分光光度计操作条件： ················································································ 1 4.检测方法 ··································································································· 1
4.1 试剂 ······················································································································ 1 4.2开机准备 ················································································································ 1
5方法验证 ··································································································· 2
5.1 线形范围 ················································································································ 2 5.2 检出限 ··················································································································· 3 5.3 定量下限 ················································································································ 3 5.4 最低检出浓度 ·········································································································· 4 5.5 精密度 ··················································································································· 4 5.6 准确度 ··················································································································· 4
6.验证结论 ··································································································· 5
附录1：验证所需设备和仪器仪表汇总 ··············································································· 5 附录2：验证原始记录 ···································································································· 5
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1. 概述
本文件验证了工作场所空气中甲醛的分光光度法本检测方法实施细则参照 GBZ/T 160.54-2004 《工作场所空气有毒物质测定脂肪族醛类化合物》中甲醛的酚试剂分光光度法的定量测定为主要依据，以及在此标准的基础上根据本检测中心实际配置的仪器和实验条件的情况下将标准中的技术要素编写了相关的作业指导书。
为了保证此分析方法的可行性、准确性、可操作性和适用性、用科学的方法进行相应的验证程序特别编写了此验证方案，为今后在实际工作中将起到指导和借鉴的作用。
在验证空气中甲醛的测定方法中，做了方法的线性范围实验、检出限实验、方法精密度实验、准确度实验，以证明该方法适用于测定工作场所空气中甲醛的的浓度。 2. 目的
通过验证工作，确保测定工作场所空气中甲醛浓度的分析方法在广德众康职业卫生检测服务有限公司适用。 3. 分光光度计操作条件：
仪 器 波 长 比色皿 参比溶液
4.检测方法 4.1 试剂
实验用水为蒸馏水
4.1.1酚试剂：称量0.10g酚试剂，加水溶解，倾于100ml具塞量筒中，加水 至刻度。
4.1.2: 硫酸铁铵溶液：称量1.0g硫酸铁铵，用0.72mol/L硫酸溶解，并稀释至100ml。 4.1.3:标准溶液：量取2.8mL含量为36%~38%甲醛溶液，放入1L容量瓶中，加水稀释至刻度。此溶液1ml约相当于1mg甲醛。标定后溶度为0.96mg/ml的贮备液。临用前用水稀释至1.0ug/ml甲醛标准溶液。
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紫外可见分光光度计(T6新世纪) 可调波长范围190～1100nm 645nm 10*10mm 蒸馏水 ZQ
4.2开机准备
4.2.1 检查仪器，准备10mm石英比色皿。
4.2.2 打开紫外可见分光光度计，同时预热分光光度计10min
4.2.3 预热完毕，仪器自检完毕后，准备实验。
4.2.4 在成套的石英比色皿中加入参比溶液，做基线校准与校准能量。 4.2.5 校准完毕后，输入本方法所需要的波长645nm，确认，实验开始。 5．方法验证 5.1 线形范围
在3操作条件下将紫外可见分光光度计调节至最佳测定状态，标准曲线的绘制：取7只具塞比色管，分别加入0.00、0.1、0.25、0.5、1.00、1.50、2.00ml甲醛标准溶液，加水至2.6ml，各加2ml酚试剂溶液，摇匀，于43±1℃水浴中放置10min，期间摇动几次，加入0.4ml硫酸铁铵溶液，摇匀，再放入水浴中加热10min，取出放冷至室温，在645nm 波长下测量吸光度。每个浓度重复测定3 次，以吸光度均值对相应的甲醛的含量（?g）绘制标准曲线。
见表1：
表1：方法验证线性范围数据表
序号 标准含量（μg） 吸光度（A） 相关系数 线形方程 1 0.00 0.031 2 0.1 0.089 3 0.25 0.176 4 0.5 0.307 0.9980 Y=0.5036X+0.046 5 1.00 0.568 6 1.50 0.810 7 2.00 1.036 2/5
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图1：甲醛的含量与吸光度关系图
5.2 检出限
在3工作条件下将仪器调至检测状态，连续测量10次空白溶液，按公式计算检出限：
CL = 3σ/s
式中：CL — 检出限，?g/mL；
σ — 测量10次空白溶液的浓度标准偏差； s — 方法的灵敏度，即工作曲线斜率，mL/μg。
表2：连续测定10次空白溶液检出线数据
序号 吸光度值 浓度（μg /mL） 序号 吸光度值 浓度（μg /mL） 浓度平均值（mg/L） 标准偏差 1 0.031 0.00 6 0.031 0.00 2 0.031 0.00 7 0.030 0.00 0.00 0.00042 3 0.030 0.00 8 0.031 0.00 灵敏度(mL/μg) 检出限(μg/mL) 4 0.031 0.00 9 0.031 0.00 5 0.031 0.00 10 0.031 0.00 0.5036 0.0025 从表2得到本方法检出限结果：0.0025μg/mL ，低于方法检出限0.04μg/mL，符合检测要求。 5.3 定量下限
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