Commonly Used Sample Preservation Techniques for Laboratory Water – Table 4 (Various Heavy Metals, etc.)

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The table lists the requirements for water sample preservation techniques. The preservation time, container material selection, and preservation measures all depend on the components and properties of the sample. However, real-world water samples vary greatly, so the requirements listed in the table cannot be absolute guidelines. Therefore, each analyst should verify the applicability of these requirements in their specific work, and the methods for sample collection and preservation should be clearly specified when developing analytical method standards.

Furthermore, if there are incompatibilities between the analytical method to be used and the protective agent and container material, it is often necessary to take several samples from the same water body and analyze them using different preservation methods to determine the most suitable protection method and container.

Common Sample Preservation Techniques – Table 4

(This table only contains general requirements for sample preservation. Due to the complex properties of natural water and wastewater, the stability of each type of sample treated according to the following methods needs to be verified before analysis.)

1 Project to be tested		2 Container Category	3 Save method	4 Analysis location	5 Storage time	6 suggestion
A thing reason , change study and born change point Analysis	chlorophyll	P or G	Refrigerate at 2-5℃ Cryogenic filter cake after filtration	laboratory laboratory	24h January
	hydrazine	G	Adjust the concentration to 1 mol/L with HCl (100 mL per liter of sample) and store in the dark.	laboratory	24h
	Detergent	See surfactants
	mercury	P, BG		laboratory	2 weeks	The method of storage depends on the method of analysis.
	aluminum	P	Used for on-site filtration wells	laboratory	January	Filter residue is used to determine the non-filterable state.
	Filterable aluminum		Acidify the solution with nitric acid until the pH is <2 (if atomic absorption spectrometry is used for the determination, acidification with H2SO4 cannot be used).
	Aluminum adhering to suspended matter		On-site filtration	laboratory	January
	Total aluminum		Acidify to pH < 2	laboratory	January	H2SO4 cannot be used when determining acidification after digestion of a homogeneous sample.
	barium	P or G	See aluminum
	cadmium	P or BG	See aluminum
	copper		See aluminum
	Total Railway	P or BG	See aluminum
	lead	P or BG	See aluminum			H2SO4 cannot be used during acidification.
	manganese	P or BG	See aluminum
	nickel	P or BG	See aluminum
	silver	P or DG	See aluminum
	tin	P or BG	See aluminum
	uranium	P or BG	See aluminum
	Zinc	P or BG	See aluminum
	Total Chromium	P or G	Acidification makes pH < 2	laboratory	ASAP	Containers with ground joints or roughened inner walls must not be used to avoid chromium adsorption.
	Hexavalent chromium	P or G	Adjust the pH to 7-9 using sodium hydroxide.	laboratory	ASAP