EPA Methods such as 524.2 and 525.2 have specified preservation and holding time conditions for compliance monitoring, but there are clear inconsistencies between various analytical method specifications. When shipping from outside the conterminous USA, there are difficulties in either maintaining sample temperatures during shipment or regulatory constraints limiting the ability to use hazardous substances such as acids in preservation. Additionally there are pesticides that are regulated under WHO guidelines that are not listed in EPA methods and therefore have no data on preservation or holding time. An evaluation of holding time and various preservation options was conducted for a number of classes of compounds as part of a global study of water quality for a major beverage manufacturer. This study demonstrated that most VOCs were stable for extended periods of time (up to 28 days) without refrigeration or acidification. However there were some significant exceptions where refrigeration was critical for stability. Pesticide and SOC stability was highly dependent on the compound and preservation options selected. Some pesticides were more stable at neutral pH and others were only stable under low pH conditions. Refrigeration had a large positive effect on stability of the pesticides and SOCs in general.

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