别等、别催，我是海绵，也是奶牛。若有需要，可以关注我或者这个专辑。
当然，也可能还没有建立专辑。
1251 WEIGHING ON AN ANALYTICAL BALANCE应用分析天平进行称量
INTRODUCTION简介
Weighing is a frequent step in analytical procedures, and the balance is an essential piece of laboratory equipment. The general information described here applies directly to electronic balances used in analytical procedures. Although many portions of the chapter are applicable to all balances, some are applicable only to analytical balances. This chapter should not be considered all-inclusive, and other sources of information (e.g., the US National Institute of Science and Technology and balance manufacturers) may be useful and applicable when analysts perform a weighing operation or implement a weighing procedure. The information given in this chapter is applicable not only to balances used for materials that must be accurately weighed (see Balances 41) but also to balances used in all analytical procedures.
称重是分析过程中一个常规步骤，天平是实验室中必不可少的设备。这里描述的通用信息十分适用于分析过程中使用的电子天平。虽然本章的很多部分适用于所有天平，但有些部分只适用于分析天平。本章并非万金油，当分析师执行称重操作或执行称重程序时，其他信息来源(例如，美国国家科学技术研究所和天平制造商)可能是有用和适用的。本章中给出的信息不仅适用于必须精确称量的物料的天平(参见天平<41>)，也适用于所有分析程序中使用的天平。
QUALIFICATION确认
Users should consult Analytical Instrument Qualification 1058, standard operating procedures, and recommendations from manufacturers when they devise qualification plans. 当用户设计确认计划时，应查询AIQ<1058>、标准操作程序和制造商的建议。
Installation安装
The balance’s performance depends on the conditions of the facility where it is installed. Analysts should consult information provided by the manufacturer before they install a balance.
天平的性能取决于安装它的设施的条件。分析员在安装天平前应咨询制造商提供的信息。
SUPPORT SURFACE支撑面
The balance should be installed on a solid, level, nonmagnetic surface that minimizes the transmission of vibration (e.g., a floor-mounted, granite weigh bench). If a metallic support surface is used, the surface should be grounded in order to prevent the buildup of static electricity.
天平应安装在坚固、水平、无磁性的表面上，以最大限度地减少振动的传递(例如，安装在地板上的花岗岩称量台)。如果使用金属支撑面，表面应接地，以防止静电的积聚。
这里好好怀念一下被我亲手砸掉的大水泥台子
LOCATION安装位置
If possible, the balance should be located in a room that is temperature and humidity controlled. The location should have a clean, consistent electrical power supply. The location should be free of drafts and should not be near ovens, furnaces, air conditioner ducts, or cooling fans from equipment or computers. The balance should be positioned away from outside windows so that direct sunlight does not strike the balance. The balance should not be installed near sources of electromagnetic radiation such as radio-frequency generators, electric motors, or hand-held communication devices (including cordless telephones, cellular telephones, and walkie-talkies). The balance should not be located near magnetic fields induced by laboratory instrumentation or other equipment.
如果可能的话，天平应该放在温度和湿度可控的房间里。该位置应有一个清洁、稳定的电力供应。该位置应无通风、不应靠近烘箱、熔炉、空调管道或设备或电脑的冷却风扇。天平的位置应该远离窗户，以免阳光直射。天平不应安装在电磁辐射源附近，如射频发电机、电动机或手持通信设备(包括无绳电话、移动电话和对讲机)。天平不应放置在实验室仪器或其他设备引起的磁场附近。
The performance of the balance should be assessed following installation and before use in order to demonstrate adequate performance. In some situations, it may not be possible to position the balance in an optimum environment. Examples of potential facility issues include the following:
天平的性能应在安装后和使用前进行评估，以证明其足够的性能。在某些情况下，可能不可能将天平放置在最佳环境中。潜在设施问题的例子包括:
1.Air currents sometimes are present in the laboratory. 实验室里有时存在气流。
2.Temperatures in the laboratory vary excessively (check the manufacturer’s literature about temperature sensitivity).较快 的实验室温度变化 (查阅制造商关于温度敏感性的文献)。
3.Humidity is either very low or very high. Either condition may increase the rate at which the sample weight varies because of pickup or loss of water. Low humidity increases the buildup of static electricity. 湿度忽高忽低。因为水分的增加或逸失，任何一种情况都可能增加样品重量变化的速率。低湿度会增加静电的积聚。
4.Adjacent operations are causing vibration. 相邻操作引起震动。
5.Corrosive materials are used nearby or are routinely weighed. 腐蚀性材料无保护称重或就近使用。
6.The balance is located within a fume hood because it is used to weigh corrosive or hazardous materials. 因为用于称腐蚀性或有害物质，天平被安放在通风柜内。
7.The balance is adjacent to equipment that produces a magnetic field (e.g., a magnetic stirrer). 天平靠近产生磁场的设备(如磁力搅拌器)。
8.Direct sunlight strikes the balance. 阳光直射天平。
In situations when the balance is located near equipment or systems that induce vibration, drafts, electromagnetic radiation, magnetic fields, or changes in temperature or humidity, the assessment should be conducted with those systems operating in order to duplicate a worst-case scenario.
如果天平位于会引起振动、气流、电磁辐射、磁场或温度或湿度的变化的设备或系统附近，评估应在这些系统运行时进行，以便重现最坏情况。
Operational Qualification操作确认
An operational qualification should be performed either by the user or by a qualified third-party vendor after the equipment has been installed.
设备安装后，应由用户或有资质的第三方供应商进行操作确认。
As a minimum, the power should be turned on and the balance should be allowed to equilibrate according to the manufacturer’s instructions (1–24 h, depending on the type of balance) before use. Depending on the balance, analysts should include the following procedures in the operational qualification:
在使用前，至少要打开电源，并让天平按照制造商的说明书进行平衡(1-24小时，根据天平的类型而定)。根据天平的不同，分析师应在操作确认中包括以下程序:
1.Mechanical mobility of all moveable parts 所有可移动部件的机械机动性
2.Control of stable indication 稳定指示的控制
3.Manually triggered or automatic adjustment by means of built-in weights 手动触发或内置砝码自动校正
4.Operation of ancillary equipment 辅助设备的操作
5.Tare function 去皮功能
6.Initial calibration 首次检定（外边说法：校准）
Several types of electronic analytical balances use built-in weights for manually triggered or automatic adjustment. This adjustment usually is applied to reduce the drift of the balance over time and to compensate for drifts caused by variations in the ambient temperature.
一些类型的电子分析天平使用内置的重量手动触发或自动调整。这种调整通常适用于：减少平衡随着时间的推移而漂移；补偿因环境温度变化而引起的漂移。
Calibration normally is performed as part of the operational qualification, but it also can be performed periodically thereafter.
Calibration should be performed at the location where the balance is used in normal operation.
校准通常是操作确认的一部分，但之后也可以定期进行校准。校准应在天平正常使用的地方进行。
