As industry standards continue to advance, analytical instruments are becoming more sensitive with lower detection limits. Concurrently, there is a corresponding increase in the water quality requirements for laboratory use. Conventional bottled water and purified water are gradually proving inadequate to meet the demands of analytical testing, leading more users to consider ultrapure water systems. However, due to the multitude of brands and varying features of ultrapure water equipment, users often find themselves in a quandary when making a purchase decision. Selecting an ultrapure water system that aligns with their specific requirements has become a pressing concern in today’s context.

Today, I’d like to discuss the topic of selecting an ultrapure water system for your laboratory

01. Clarify the Laboratory’s On-Site Water Supply Situation

In laboratory settings, there are generally two types of water sources: tap water and purified water.

  • If the laboratory only has access to tap water, then it is necessary to select an ultrapure water system that uses tap water as its feedwater source. However, if the quality of the tap water on-site is poor, for example, if it contains a high level of sediment or has high hardness, it’s essential to inform the water purification system manufacturer in advance. This is crucial to add pre-filtration units to the system, as otherwise, it can significantly affect the water quality of the ultrapure water system and the lifespan of consumables.
  • If the laboratory already has a supply of purified water, you can opt for an ultrapure water system that uses purified water as its source. In this case, it’s important to inform the system manufacturer about the quality of the purified water and whether it is pressurized. Generally, when using purified water as the feedwater source for an ultrapure water system, it should meet at least the standards of Type III water quality.

02. Determine the Laboratory’s Water Requirements

Once the water source is established, the next step is to determine the specific water quality requirements for your laboratory experiments.

a. Selecting Based on Water Quality

In accordance with the Chinese standard “Specifications for Laboratory Water for Analysis,” laboratory water is categorized into three grades: Grade I water, Grade II water, and Grade III water.

Most laboratories typically require two grades of water. Grade III water is commonly used for tasks like cleaning laboratory glassware, while Grade I water is used for precision analytical instruments such as chemical analysis, liquid chromatography, atomic absorption, etc. Users should choose the appropriate level of water purification equipment based on their specific water quality requirements.

Therefore, it’s important for users to assess their laboratory’s water quality needs and select the corresponding grade of purified water equipment accordingly.

If users are unsure about their specific water quality requirements in practice, they can also consider the following two points:

For standard physical and chemical experiments, Grades I and II water (with a resistivity greater than 1 MΩ·cm) are sufficient. Inorganic trace analysis experiments, which primarily involve instruments like Ion Chromatography (IC), Atomic Absorption Spectroscopy (AAS), Inductively Coupled Plasma (ICP), and ICP-Mass Spectrometry (ICP-MS), typically require water with a resistivity greater than 18 MΩ·cm.

These are primarily used in applications such as chromatography, mass spectrometry, absorbance measurements, reagent production, and trace element analysis, among others. If the experiments involve biological aspects, such as water for protein purification, sterile preparations, medical device rinsing, cell culture, in vitro fertilization, general biochemical applications, Next-Generation Sequencing (NGS), Polymerase Chain Reaction (PCR), and more, microbial indicators should also be considered.

c. Based on Instrument Type

Users can select a laboratory ultrapure water system based on the type of instruments they use.

For water used in HPLC, LC-MS, IC, and GC-MS instruments, it should have a resistivity greater than 18 MΩ·cm and should be free from organic impurities.

For instruments like Atomic Absorption Spectroscopy (AAS), Atomic Fluorescence Spectroscopy, and environmental monitoring instruments, a resistivity greater than 18 MΩ·cm is sufficient.

For life science instruments like PCR and others, the water should have a resistivity greater than 18 MΩ·cm and should also be free from microbial contaminants, organic impurities, and thermal contamination.

The three points mentioned are based on practical application experience and can serve as a reference. However, for accurate model selection, it’s advisable to provide detailed water quality parameters such as resistivity, trace elements, bacterial counts, total organic carbon levels, etc. It’s important to note that some water purification systems labeled as “ultrapure water systems” may not meet the specific requirements of having a resistivity greater than 18 MΩ·cm, even if they are considered Grade I water. In such cases, it’s crucial to carefully examine the system’s specifications and, if necessary, request water quality test reports from the manufacturer.

03. Determine Water Usage

Once the purpose of the equipment and the required water quality are established, you can select the appropriate equipment based on the laboratory’s daily water usage.

It’s generally recommended to follow the 2x principle. For example, if the daily water usage is 40 liters, you should choose a machine with a capacity of 20 liters per hour. If you select a machine with a capacity that is too small, the consumables for the ultrapure water system will be depleted quickly. On the other hand, if you choose a machine with a capacity that is too large, it may lead to resource wastage. If there is a significant demand for water in a centralized location, you may need to purchase a larger pure water storage tank to ensure that the water production rate meets the laboratory’s needs. This helps avoid situations where the water production rate cannot keep up with the experimental requirements.

In addition, users in northern regions should be aware that water viscosity is influenced by temperature, and the water production rate of reverse osmosis membranes will decrease as the temperature drops. During the winter, the water production rate of laboratory ultrapure water systems may be lower compared to the summer months. Therefore, when selecting an ultrapure water system with RO (reverse osmosis) components, it’s advisable to consult with the manufacturer to see if they offer features or solutions to mitigate the impact of temperature on water production.

04. Confirm Consumable Lifespan and Prices

Over the years, the frequent replacement of consumables has kept the operating costs of water systems relatively high. Generally, each manufacturer’s consumables will have an upper limit in terms of the volume of water they can process or the time they can be used. Users can estimate the operating costs of an ultrapure water system based on these two parameters.

Domestically produced ultrapure water consumables have seen significant development over the years. When compared to imported consumables, the performance gap is not significant, but the prices are considerably lower. Therefore, choosing domestically produced ultrapure water systems can be a cost-effective option.

05. Regarding Operation and Maintenance

The ease of use of an instrument is one of the important criteria for evaluating its quality. Often, users prefer instruments with straightforward and user-friendly interfaces, avoiding overly complex control systems and excessive parameter settings. For ultrapure water systems, user-friendliness is determined by whether the system allows operators to simply press a water dispensing button without requiring additional complicated procedures or settings.

Additionally, the replacement of consumables and maintenance of ultrapure water systems have always been critical factors affecting the user experience. Having an ultrapure water system that can perform automatic maintenance and allows users to easily replace consumables themselves can greatly enhance the user experience.

Furthermore, selecting an ultrapure water system that meets the laboratory’s requirements involves more than just producing high-quality ultrapure water. Users also expect the system to have additional features that enhance stability and functionality. Additionally, considering the quality of after-sales service is crucial. Choosing a system from a reputable and well-known manufacturer can alleviate many potential concerns.

That concludes our discussion on the selection of laboratory ultrapure water systems. We hope this information is helpful to you.

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