Commonly Used Sample Preservation Techniques for Laboratory Water – Table 6 (Chloride, Fluoride, 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 6

(The content of this table only represents 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	Drill calcium	P or BG P or BG	See aluminum-filtration The filtrate was then acidified to pH < 2.	laboratory laboratory	24 hours a day	_H₂SO₄for acidification _.Acidified samples can be used simultaneously for the determination of calcium and other metals .
	Total Hardness		See calcium
	magnesium	P or BG	See calcium
	Keng	fl	Acidify to pH < 2	laboratory
	Potassium	P	See lithium
	uranium	P	See lithium
	bromides and bromine-containing compounds	P or G	Refrigerate at 2-5℃	laboratory	ASAP	Samples should be stored away from light.
	chloride	P or G		laboratory	Several months
	Fluorides	P		laboratory	If the sample is neutral, it can be stored for several months.
	iodide	Non-photochemical glass	Adjust the pH to 8 by adding alkali when refrigerated at 2-5℃.	laboratory	24h 1 month	Samples should be kept away from direct sunlight.
	orthophosphate	BG	Refrigerate at 2-5℃	laboratory	24h	The sample should be filtered immediately and the dissolved phosphates should be analyzed as soon as possible.
	Total phosphorus	BG	Acidify with H2SO4 until pH < 2	Laboratory Laboratory	24 hours several months
	selenium	G or BG	Adjust the pH to >1.1 using NaOH.
	silicates		Filter and acidify with H2SO4 to pH < 2, then refrigerate at 2–5°C.	laboratory	24h
	Total Silicon	P		laboratory	Several months
	sulfates	P or G	Refrigerate at 2-5℃	laboratory	One week
	sulfites	P or G	Add 1 mL of 25% (m/m) EDTA solution per 100 mL of water sample on site.	laboratory	1 week
	Boron and borates	P		laboratory	Effective Month