Commonly Used Sample Preservation Techniques for Laboratory Water – Table 2 (Residual Chlorine, Oils, Carbon, etc.)

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Common Water Sample Preservation Techniques

The table lists the requirements for water sample preservation techniques. The preservation time, container material selection, and application of 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 sample collection and preservation methods 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 2

(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	Residual chlorine	P or G		on site		It is best to analyze on-site, such as If that's not possible, use it on-site. Excess NaOH fixation. (Preservation) Storage should not exceed 6 hours
	carbon dioxide	P or G		See pH level
	Dissolved oxygen	(dissolved oxygen bottle)	On-site fixed oxygen Store in the dark	On-site, laboratory	a few hours	Add 1 mL of 1 mol/L iodometric titration Potassium permanganate and 2 mL 1 mol/ Alkaline potassium iodide
	Fats, oils, carbon Hydrogen compounds, stone Oils and derivatives	Rinse the container with the solvent used in the analysis.	On-site extraction Freeze to -20°C	Laboratory Laboratory	24 hours a day	It is recommended to do this immediately after sampling. Add to the analysis method The extractant used, or the input On-site extraction
	Ionic Tablet surfactant	G	Refrigerate at 2.5℃ Sulfuric acid acidification pH < 2	laboratory laboratory	as soon as possible (48 hours)
	Non-ionic type surfactant	G	Add 40% (v/v) formaldehyde to make the sample contain 1% (v/v) formaldehyde. The aldehyde solution should be refrigerated at 2–5°C, and the container should be filled with water sample.	laboratory	January
	arsenic		Add H2SO4 to make pH < 2 Adjust pH to 12 by adding alkali	Laboratory Laboratory	Several months	Nitric acid acidification cannot be used. Domestic sewage and industrial waste Water should be used in this way
	sulfides		Add 2 mL per 100 mL Add 2 mol/L zinc acetate to 2 mL of 2 mol/L NaOH and refrigerate.	laboratory	24h	Must be fixed on site
	Total cyanide	P	Adjust the pH to >12 using NaOH.	laboratory	24h