There are many and complex reasons for the unqualified inspection items in the purified water section. The brands of pure water machines and water production principles of various production enterprises are different, and the factors that cause unqualified water production processes are also different. Here, we can only list the common reasons related to them for discussion with everyone, and cannot fully cover them. Please provide valuable opinions and work together to further improve the quality of purified water.
5、 The country has established the industry standard YY/T 1244-2014 for purified water used in vitro diagnostic reagents, which includes 5 items for inspection, excluding pH. The national bureau requires purified water for in vitro diagnostic reagents to be tested within 2 hours from sampling to submission. If conditions do not allow, it must be refrigerated and submitted for testing within 6 hours. The Chinese Pharmacopoeia does not specify the time from sampling purified water to submission for testing. Time may have an impact on the test results, so we need to carefully study and explore it in the future.
1、 Reasons for the unqualified conductivity of purified water treatment equipment effluent
1. Raw water: The quality of the raw water has changed, and the conductivity of the raw water has increased, which naturally affects the production of water
2. Preprocessing: Mechanical filters and activated carbon filters are not regularly and timely backwashed (resulting in a relative increase in inlet conductivity);
3. Reverse osmosis system: The original components of the reverse osmosis membrane are damaged or have exceeded their service life and need to be replaced The security filter for reverse osmosis inlet water is clogged and the pressure difference is large, so the filter element was not replaced in time; When the desalination rate of the reverse osmosis system decreases and the water production rate decreases by 10% or the reverse osmosis inlet pressure increases by 10%, timely cleaning is not carried out;
4. In terms of operation: whether the operation and maintenance of the purified water equipment are strictly in accordance with the requirements; Is the water temperature during water production within a reasonable range, and is the pH value of the inlet water within a reasonable range; The recovery rate can be adjusted appropriately to improve the conductivity of the produced water; If the purified water treatment equipment system has been running for 2-5 years and the water production time is relatively long, and has been well cleaned, but the conductivity of the purified water is often high, it indicates that the reverse osmosis membrane needs to be replaced.
2、 Possible reasons for the increase of nitrite
1. After sand filtration and activated carbon treatment, some require steam sterilization, and the heat exchanger used is not cleaned for a long time, resulting in repeated boiling and an increase in nitrite in the water.
2. UV lamp disinfection increases nitrite levels, and the purified water before and after disinfection can be checked for nitrite levels.
3. The appearance of unqualified nitrate in general purified water is that the conductivity is qualified and the nitrate or nitrite exceeds the standard. This is one of the difficult and complicated problems of reverse osmosis, usually caused by microbial contamination. The mechanism is that under anaerobic conditions, anaerobic respiration using nitrate as an electron acceptor will produce nitrite. Solution: A chemical cleaning usually uses about 2% sodium hydroxide, and a comprehensive disinfection can solve this problem for a long time. If it still doesn't work, it is recommended to disinfect the activated carbon filter in the system, replace the membrane components, and replace the pure water pipeline.
3、 Reasons for the increase in non-volatile substances
1. A container for holding water
2. It is also possible for the reverse osmosis membrane to be damaged.
3. You can try using ion exchange resin mixed bed.
4、 Reasons for pH exceeding the range
1. Reason for acidity: resin is contaminated by metal ions; High CO2 content; Microbial contamination produces acid
2. Reason for high deviation: Is there a mineralized filter element added? The normal pH value of a pure water machine is lower than that of raw water, but if a mineralized filter element is added, the pH value may increase because the mineralized filter element contains alkaline minerals
3. If it is ultrapure water (primary and secondary water), pH cannot be measured for a long time because the ion content in the water is particularly low, and the pH value cannot be accurately measured.
5、 The country has established the industry standard YY/T 1244-2014 for purified water used in vitro diagnostic reagents, which includes 5 items for inspection, excluding pH. The national bureau requires purified water for in vitro diagnostic reagents to be tested within 2 hours from sampling to submission. If conditions do not allow, it must be refrigerated and submitted for testing within 6 hours. The Chinese Pharmacopoeia does not specify the time from sampling purified water to submission for testing. Time may have an impact on the test results, so we need to carefully study and explore it in the future.