An HPLC analysis result can be inaccurate even with perfectly calibrated equipment. This system error often stems from “blind spots” at the weighing and dilution points. When handling reference materials, environmental factors such as fine dust, aerosols, and air humidity are the primary causes of cross-contamination or sample denaturation. This directly distorts the analytical calibration curve and reduces the reliability of the test.

This article will provide solutions for establishing a localized, highly efficient clean working area. The content is based on stringent standards for QC/QA departments in the pharmaceutical, food, and environmental industries. Through this, managers will have additional options to optimize testing procedures within their units.

1. International Standards for Clean Laboratory Areas

1.1 Environmental Requirements according to TCVN ISO/IEC 17025

The national standard TCVN ISO/IEC 17025:2017, in section 6.3, specifies very strict requirements for laboratory facilities and environmental conditions. These factors must be controlled and recorded to avoid affecting the measurement uncertainty of analytical results. According to ISO Guide 30, Reference Materials (RM) and Certified Reference Materials (CRM) are materials with extremely high homogeneity and stability. Therefore, handling them requires a strictly controlled environment in terms of both temperature and relative humidity (RH%).

When humidity exceeds the specified threshold, organic compounds are very susceptible to hydrolysis or water vapor absorption. Conversely, temperature fluctuations will change the density of the solvent during volumetric dilution. Therefore, establishing an independent work area is essential to maintaining sample integrity.

1.2 Classification of Cleanliness Levels for Sample Handling Locations

The international standard ISO 14644-1 classifies air cleanliness based on the limiting density of suspended particulate matter. The area for weighing and preparing standard samples must achieve a minimum cleanliness level of ISO Class 5 (equivalent to Class 100 according to the old standard FED STD 209E). At this level, the number of particulate matter with a size of >= 0.1 mu must not exceed 100,000 particles per cubic meter of air. Conventional HVAC systems in buildings often create turbulent airflow. This airflow constantly moves and carries foreign particles into the weighing pan.
For analytical balances with 4-5 decimal places, this turbulent airflow also creates aerodynamic forces acting on the weighing pan. As a result, the readings on the screen fluctuate continuously, making it impossible for technicians to determine the actual weight of the sample.

2. Risk of Cross-Contamination and Errors in the QC/QA Laboratory

2.1 Mechanism of Error Formation Due to Environmental Contamination

Contamination occurs when fine dust particles or aerosols in the air fall into an open sample vial. This silent intrusion causes cross-contamination between different active substances in the same lab. For standards with hygroscopic properties, the rate of water vapor absorption occurs in just a few seconds. This process increases the apparent weight of the dry matter when weighed, leading to systematic errors in calculating the calibration curve.
According to an experimental study published in the international medical library PubMed, more than 35% of errors in high-performance liquid chromatography (HPLC) and gas chromatography-mass analysis are directly caused by alterations in the properties of standards during sample preparation (Smith & Johnson, 2022). Therefore, if samples are not protected from environmental factors, the entire subsequent analytical chain loses its legal validity.

Proper handling of reference materials is crucial to ensuring the accuracy of samples and analytical data

2.2 Risks of Hazardous Chemical Exposure to Personnel

The risk extends beyond sample damage to directly impacting human health. When laboratory technicians handle hazardous reference materials or highly potent APIs, the risk of exposure is significant. If working in an open space, ultrafine chemical particles will freely disperse into the medical air. Laboratory personnel inhaling these particles over extended periods will face dangerous chronic respiratory illnesses.

Therefore, a localized negative-pressure cleanroom is mandatory for hazardous compounds. This design both protects samples and creates a safe isolation barrier for personnel.

3. Standard Operating Procedures for Creating a Clean Work Area

3.1 Pre-treatment Steps for a Clean Work Area

To establish a sterile work space that meets standards, the pre-treatment process must be strictly followed. Before starting, technicians need to clean the work surfaces with 70°C specialized alcohol. Next, the UV irradiation system for disinfection must be activated for a minimum of 30 minutes to completely eliminate microorganisms. At the same time, the differential pressure of the filter membrane must also be checked to ensure the airflow system operates stably.
In parallel with equipment preparation, personnel are required to wear full specialized personal protective equipment (PPE). This includes powder-free gloves, high-performance medical masks, and anti-static gowns. These accessories are designed to retain dead cells and lint from everyday clothing.

3.2 Rules for Arranging Tools in the Clean Zone

The arrangement of space within the clean zone follows fluid dynamics principles. All original reference standard vials and diluent solvents must be placed upstream of the clean air stream. Conversely, waste recovery equipment or used tools must be located downstream. This procedure allows the clean air to pass through the sample before contact with high-risk contamination sources.

In particular, technicians must not place their hands or large obstructions directly in front of the filter membrane. This action will disrupt the laminar flow structure, creating swirling low-pressure areas that cause dust particles to accumulate inside the work cabinet.
Register to receive relevant ISO 17025 documents

4. AD-600 Standard Freezer: Optimal Preservation Solution

4.1 Intelligent Temperature and Humidity Control Features

Besides a clean workspace, long-term storage directly affects sample stability. Currently, the AD-600 Standard Freezer distributed by Duc Duong is the optimal hardware solution for commercial laboratories. The device boasts a wide temperature range for storage with extremely high control accuracy (+- 0.5°C). The structure of the internal trays is intelligently designed, allowing managers to easily classify and locate small-capacity sample vials.
The outstanding feature of this freezer lies in its active anti-frost technology combined with a strict humidity control system. This mechanism completely eliminates the risk of condensation on the vial walls, protecting barcode labels from peeling and preventing water from entering the core of the material.

AD-600 standard substance processing cabinet distributed by Duc Duong

4.2 Ưu thế công nghệ so với tủ lạnh dân dụng

Technical Specifications	AD-600 Specialized Freezer	Standard Household Refrigerator
Temperature Uniformity	Achieves a temperature of +- 1.0°C at all points thanks to a continuous convection fan system.	Temperature differences between shelves can reach 3°C – 5°C.
Temperature Recovery Speed	Under 5 minutes after opening the door thanks to a high-performance compressor.	Prolonged recovery time of 20-30 minutes poses a risk of thermal shock to sensitive samples.
Safety Warnings	Integrated alarm and indicator light when the temperature exceeds the threshold or the door is left open for too long.	No active warning system for the user.

The data matrix table above shows that household refrigerators cannot meet the stringent storage standards in pharmaceutical testing laboratories. Investing in specialized equipment is a sustainable solution to protect the unit’s valuable reference materials.

5. ASONE Japan’s Mobile Cleanroom Equipment

5.1 High-Performance HEPA/ULPA Filter Technology

For laboratories with limited space, building a large-scale cleanroom is extremely expensive. In that case, using mobile cleanroom modules from the leading Japanese science company ASONE is a perfect alternative. Users can check the official certification parameters of the equipment at ASONE International. The heart of this system is the high-performance HEPA or ULPA filter. The filter membrane is capable of retaining up to 99.97% of dust particles with a diameter of 0.3 mu.

The integrated fan system inside the cabinet continuously draws in ambient air, forces it through the filter membrane, and blows out a straight stream of sterile air. This clean air stream continuously sweeps through the standard processing area, creating a localized positive pressure zone to prevent any dust particles from entering from the outside.

5.2 Advantages of Mobile Design for Installation on Weighing Platforms

The biggest advantage of the ASONE cleanroom equipment line is its intelligent and highly customizable design. With its compact size, this module can be placed directly on existing anti-vibration weighing platforms in the QC room. Installation is quick and does not require breaking down walls or interfering with the building’s main HVAC system.

This solution optimizes initial investment costs for businesses while still ensuring the weighing area meets ISO Class 5 standards. Technicians can work with complete peace of mind in a safe and accurate workspace.

6. Comparison of straight-flow cabinets and Class II biological safety cabinets

6.1 Comparison matrix of sample and operator protection capabilities

Comparison Criteria	Laminar Flow Bench	Biosafety Cabinet Class II (BSC Class II)
Airflow Direction	Clean air blows from back to front or from top to bottom and then straight out towards the operator.	Clean air flows downwards, partly recirculated, and partly passing through an exhaust filter creating a negative pressure barrier at the door.
Protection Purpose	Only protects the sample inside the cabinet; does not protect the operator at all.	Simultaneously protects: the test sample, lab personnel, and the surrounding environment.
Applicable Standards	ISO 14644-1 (Particulate matter density control).	NSF/ANSI 49 or EN 12469 (Biological safety).

The comparison matrix above clarifies the aerodynamic nature of the two types of cabinets often confused in laboratories. Clearly distinguishing their functions helps managers make accurate purchasing decisions, avoiding budget waste.

6.2 Warnings about mistakes when choosing the wrong type of standard handling cabinet

A serious mistake often seen in QC laboratories is using straight-flow cabinets to handle hazardous standard substances. Due to the mechanism of blowing air directly from the filter towards the user, all chemical dust or toxic solvent vapors will be pushed directly into the respiratory system of the tester. This action seriously violates occupational safety standards in biochemical laboratories.

Therefore, for standard samples belonging to the group of toxic substances, microbiological samples, or radioactive substances, it is mandatory to use a Class II biological safety cabinet. This equipment ensures that the toxic gas flow is completely retained in the filtration system before being released into the environment.
(Read more: Safety risks when analyzing proteins using the manual Kjeldahl method to raise awareness of technician health protection.)

7. Periodic Clean Area Validation and Calibration Procedure

7.1 Particle Counting and HEPA Filter Inspection

The performance of air filtration systems degrades linearly over operating time. ISO 14644-2 specifies the frequency and method of periodic monitoring for clean rooms and localized clean equipment. Periodically, every 6 to 12 months, the QC department must use a laser particle counter to reassess the cleanliness level of the work area. If the particle density exceeds the permissible limit of ISO Class 5, the HEPA filter needs to be checked for leaks and replaced promptly.

In addition, the operating time of the UV sterilization lamp also needs to be closely monitored. Typically, after 1000 to 1500 hours of use, the radiation intensity of the lamp will drop significantly below the germicidal level, even though the lamp remains lit.

7.2 Building a Legally Compliant IQ, OQ, and PQ Validation Documentation

In the pharmaceutical and food industries, all equipment that interferes with the quality of test results must have validation documentation. This process includes three stages: Installation Validation (IQ), Operation Validation (OQ), and Performance Validation (PQ). The IQ documentation proves that the equipment is installed according to the technical drawings; the OQ documentation confirms that the wind speed and differential pressure parameters meet the design standards; the PQ documentation confirms that the equipment maintains stable cleanliness when personnel are actually operating it.
The complete storage of these calibration certificates is a mandatory condition for the factory to pass GMP/GLP inspections. This also serves as scientific evidence confirming the metrological traceability of all measurements.

Conclusion

Establishing a Class 100-compliant local clean working area is key to completely eliminating systematic errors and the risk of cross-contamination when handling reference materials in QC/QA laboratories. Combining specialized storage equipment such as the AD-600 freezer with the ASONE Japan mobile clean module system provides an optimal, efficient, and sustainable investment solution for testing centers.
Contact Duc Duong Science and Technology Company today to receive expert advice from our experienced engineering team and get a preferential price quote for high-quality, fully certified IQ/OQ/PQ laboratory equipment.

 

DUC DUONG SCIENCE AND TECHNICAL COMPANY

Address: 1014/67 Tan Ky Tan Quy, Binh Hung Hoa, Binh Tan, HCM

Tel: (028) 3762 8042 – 3762 8043 – 3750 8514 – 3750 8793

Fax: 028 37628043

Email: ducduong@ducduongco.com

Website: ducduongco.com

ZALO OA: DUC DUONG SCI

 

FAQ – Frequently Asked Questions about Standard Handling

1. How often should the HEPA filter of a portable cleanroom be replaced?

Under standard operating conditions in QC/QA laboratories, a typical HEPA filter has a lifespan of 2 to 3 years. However, the unit is required to perform differential pressure measurements or particle counts periodically every 6-12 months. If the differential pressure exceeds the manufacturer’s recommended threshold or the particle density does not meet Class 100 standards, the filter must be replaced immediately to avoid damaging the test sample.

2. Can a 5-decimal place analytical balance be placed directly inside the ASONE straight-flow air cabinet?

Absolutely, but technical precautions must be observed. The clean air flow through the HEPA filter always has a certain wind speed (approximately 0.3 – 0.5 m/s), which can easily cause fluctuations in the display of the ultrafine analytical balance. To ensure thorough disinfection, the operator needs to adjust the exhaust fan speed to a suitable low level or install additional specialized wind shields around the weighing plate inside the mobile cleanroom.

3. Does continuous UV sterilization affect the quality of the stored standard vials?

There is a very high risk if no shielding is used. High concentrations of UV-C radiation can trigger photochemical reactions, degrading the structure or reducing the concentration of light-sensitive organic compounds. Therefore, technicians should only turn on the UV lamp to sterilize the interior space of the cleanroom when the sample vials are tightly sealed, and it is best to store them in specialized light-resistant equipment such as the AD-600 standard freezing cabinet.

4. Which unit provides the IQ/OQ/PQ documentation for the cleanroom generator and what is its legal validity?

This set of documents will be provided by an independent calibration/auditing organization certified to ISO/IEC 17025, or directly by the specialized engineering team of the distributor Duc Duong in collaboration with the factory’s QA department. This is the highest-valued legal evidence to be submitted to the Ministry of Health or international accreditation organizations when conducting a comprehensive GMP/GLP standard assessment of the factory.