Water Quality Standards for Medical Laboratory Ultrapure Water Systems and Ultrapure Water Receivers

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When using an ultrapure water system or ultrapure water purifier, we need to understand its purpose, which is crucial for determining the required water quality standards. Today, we'll outline the relevant water quality standards for medical use:

I. Chinese Pharmacopoeia (2016 Edition) Purified Water:

Project	Chinese Pharmacopoeia (2016 Edition) Purified Water:
Source	This product is prepared by distillation, ion exchange, reverse osmosis, or other suitable methods.
Properties	Colorless, clear liquid; odorless and tasteless.
PH	5.0-7.0
Oxides, sulfates and calcium salts, carbon dioxide	Qualitative testing
Nitrates	<0.06ppm	<0.06ppm
Ammonia	<0.3ppm	<0.2ppm
Heavy metal	<0.5ppm	<0.5ppm
Total microbial count	No more than 100 per 1ml	No more than 100 per 1ml
Bacterial endotoxins	——	<0.25 EU/ml
Electrical conductivity (25 degrees Celsius)	<5.1μS/cm	<1.3μS/cm
Total organic carbon	<0.50mg/l	<0.50mg/l

II. US Standards for Pharmaceutical Grade Water (CAP, ASTM, NCCLS)

	CAP			ASTM			NCCLS
	Type I	Type II	Type III	Type I	Type II	Type III	Type I
Resistance (MΩ.cm.25C)	≥10	0.5	0.2	≥16.66	1.0	1.0	≥10
Silicon (mg/L max)	0.01	0.01	0.01	——	——	——	0.05
Heavy metal (mg/L max)	0.01	0.01	0.01	——	——	——	——
Potassium permanganate disinfection (min.min)	60	60	60	60	60	60	——
Sodium (mg/L max)	0.01	0.01	0.01	——	——	——	——
Ammonia (mg/L max)	0.01	0.01	0.01	——	——	——	10
Microorganism	Slightly	Slightly	Slightly	——	——	——	10
PH value	6.0-7.0	6.0-7.0	6.0-7.0	——	——	6.2-7.5	——

III. Water Quality Requirements for Cleaning and Disinfection (WS310.1-2016):

Types of pollutants	Maximum limit	Types of pollutants	Maximum limit
Gasification residue	10mg/l	Chloride ions (cl-)	2mg/l
Silicon dioxide (SiO₂)	1mg/l	Phosphorus pentoxide (P₂O₅)	0.5mg/l
Iron	0.2mg/l	Electrical conductivity (25℃)	5μS/cm
Calcium	0.005mg/l	pH value	5-7.5
Lead	0.05mg/l	Appearance	Colorless, clean, and free of sediment
Heavy metals other than iron, calcium, and lead	0.1 mg/L	Hardness (alkaline earth metal ions)	0.02 nmol/l
Note: Samples should be taken at the sterilizer inlet.		Note: Samples should be taken at the sterilizer inlet.

Note: The purified water source is tap water, and the water quality should meet the requirements of GB5749-2006; the conductivity of the purified water is ≤15μS/cm (25℃).

IV. Water Quality Requirements for Endoscope Cleaning (WS507-2016)

The system should include tap water, purified water, and sterile water. Tap water quality should comply with GB 5749. Purified water should also comply with GB 5749 and have a total bacterial count ≤10 CFU/100ml; the filter membrane used in the production of purified water should have a pore size ≤0.2μm and be replaced regularly. Sterile water is water that has undergone sterilization. Microbiological testing of purified water and sterile water should be performed when necessary.

References

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