USP1231《制药用水》规定了水质检验样品存放时间和存放条件的相关要求，包括化学测试样品和微生物检验的样品。概述如下：

Sampling Hold Times for Chemical Tests

化学测试样品存放时间

Basically it is advisable to conduct chemical tests immediately after extracting samples, since impurities may dissolve in water once the sample has been bottled. These impurities may be caused by contamination from ambient air or by the walls of the sample container (“leach-out”). In both cases the longer the samples are stored, the greater the potential to be adversely impacted by containers or conditions, in the worst case creating a false positive result. The proper container should be one that does not contaminate the sample during storage/hold time, eliminating the possibility that leach-out impacts certain parameter, i.e. glass bottles for the TOC assessment, plastic bottles for the measuring of the conductivity. Irrespective of the material of the container, where possible the sample should be stored cool and only for a short time in order to obtain representative results.

基本上，在取完样之后立即进行化学检验是合适的，因为一旦样品装入瓶子里之后杂质可能会溶入水里。这些杂质可能来源于环境中的空气或者取样容器的内壁（浸出）。样品存放越长，受容器或条件不利影响的可能性越大，甚至导致假阳性结果。选择合适的容器使在存放过程中不污染样品，排除浸出影响某一参数可能性，如使用玻璃瓶进行TOC检验、使用塑料瓶进行电导率测试等。除了容器材质的影响，适当时，样品应被存放于阴凉条件下，并仅存放较短时间，以获取有代表性的结果。

Sampling Hold Times for Microbiology

微生物检验样品存放时间

As in the case of the chemical tests, the new guideline adds advice on hold times for the micro-biological examination of water (chapter 8.5.1). It points out that the results of incubation during a lengthy holding time may go either way, even unintentionally improving the sample or being detrimental to it. Germs found in very clean samples (and containers) will tend to decrease over time, whereas those in an impure sample are prone to increase. Thus, the risk of false positive/negative results increases during a lengthy holding time. Therefore, the sample should be cooled during a holding time of over two hours. Incubation should take place within 24 hours. In situations where even 24 h is not possible (such as when using off-site contract laboratories), it is particularly important to qualify the microbiological sample hold times and storage conditions to avoid significant changes in the microbial population during sample storage.

正如化学检验一样，该新指南提供了水质微生物检验保存时间的建议（章节8.5.1）。它指出样品保存期间培养的结果可能会变化，或，在非常干净的样品（或容器）中发现的细菌将会随着时间不断减少，而在一个不干净的样品中，则会不断增加。这样，在保存一段时间后得到假阳性/假阴性结果的风险将会增加。因此，样品保存时间超过2个小时的，应给放置于阴凉处。培养应在24小时内进行。当24小时内培养都没办法做到时（例如当使用工厂外的合同实验室时），微生物样品保存时间和保存条件应进行确认以避免样品保存期间微生物水平发现明显变化显得尤其重要。