Milli-QÂ® Q&A | Summary of Pure Water Use Issues

Q: What is the difference between pure water and ultrapure water?
Source of question: Zhao Honghong

A:
According to the definition of the most common GB/T 6682-2008, the analytical laboratory water is divided into three levels: tertiary water, secondary water and first water. The first grade water is also the ultrapure water we often say. The third grade water and the second grade water are called purified water.

â— Three-stage water: refers to the method of distillation or ion exchange for general chemical analysis test;

â— Secondary water: refers to the method of multiple distillation or ion exchange, which can be used for partial inorganic analysis test;

â— Primary water: After being treated by quartz equipment distillation or ion exchange mixed bed on the basis of secondary water, it is filtered through 0.2Î¼m terminal filter membrane, which is often used for precision analysis equipment.

Q: How long is the life of the purification column?
Source of question: Wei Qingwen

A:
This is a very common problem, and many teachers are accustomed to have a clear use time to facilitate the management and maintenance of the laboratory water system.

However, the life of a pure water purification column is difficult to calculate under normal use conditions, mainly because:

1 The daily water consumption of each laboratory varies greatly, which leads to a big difference in the life of the purification column;

2 The quality of the influent water directly affects the life of the purification column. Under the conditions of determining the performance and capacity of the filler, the level of pollution in the water will affect the final consumable life;

Under the conditions of water quality determination, extending the life of the purification column can only be achieved by improving the performance of the purification column packing or increasing the filling amount. The new IQ 7000 ultra-pure water system:

Innovatively designed IPAK Meta and IPAK Quanta combined purification columns;

The purification column uses the patented Jetpore mixed bed ion exchange resin and the innovative IQnano ion exchange mixed packing to produce high quality ultrapure water;

The purification column is equipped with a complete performance test report;

The smaller particle size of IQ nano significantly enhances the kinetics of the resin;

Effectively remove ions from water to trace levels.

Q: How many anti-scaling agents are there in the Progard column? At what level does the influent water require additional softening columns?
Source of problem: ZYZ

Each Progard column contains approximately 500g of pyrophosphate. When the influent hardness is greater than >300ppm, an additional softening column is recommended.

Q: After the sterilization of the pure water storage tank, how do you judge whether the residual reagent content is exceeded?
Source of the problem: and listen to the wind

It is recommended to use NaOH to sterilize the water tank. Under the sterilizing state, the pH value will be around 11.5. However, after two consecutive water inflows and water release, the pH value will be checked. If it is weakly acidic, the residue has been basically removed.

The use of NaOH has two effects: Na ⁺ and pH (OH ^- ).

When the user takes ultrapure water, the 18.2MÎ© meter shows that the concentration of Na+ has dropped below 1ppb, while the pH value can be judged by pH test paper (non-pH meter). In fact, the carbon dioxide in the air is soluble. The H ⁺ produced in the water is sufficient to balance the influence of OH ^- and can exhibit a state in which the pH value is near weak acidity.