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Lab & Equipment

Implementing Quality Control in Laboratories for Reliable Results

Quality control is a critical element in laboratory monitoring that helps ensure product integrity and process accuracy.

ELPRO
Jan 12, 2022

Without quality control procedures in the laboratory, there may be no means of determining whether a product or process meets regulatory standards.

Laboratories are often sensitive facilities that demand high regard for accuracy in all processes. For example, a medical lab may conduct tests on human samples to establish pathological anomalies to ultimately inform a doctor's prognosis for a patient. As such, it is of utmost importance that reagents used in the laboratory are of the right concentration and quantity.

The process itself necessitates documentation to prevent variations that may induce errors. Without proper quality control in the laboratory, the outputs may likely be erroneous. In a worse case scenario, misleading information may be provided to a doctor who may then prescribe a fatal medication to a patient. The same applies to pharmaceutical labs, where experts manufacture medicines and vaccines.

The nature of products used and produced in the labs often necessitates stringent control measures. There must be a quality control program to validate the accuracy of the production process and ensure it meets regulatory standards. The scope of quality control includes system and process efficiency. One can maximize a lab's productivity by having the means to control quality by minimizing waste.

The concept of quality control began in the early 20th century, where the first guidelines for statistical control were applied to production lines. Early on, quality control experts realized the fallacy of focusing only on the product and ignoring the process. The first proponents of quality control advocated for the inclusion of the process in all quality control procedures to achieve better outcomes. ELPRO solutions help enable companies to carry on that quality control tradition in laboratories worldwide.

In the 1950s, Levey and Jennings introduced quality control in the medical laboratory. At a basic level, the procedure involved multiple measurements on a single patient’s sample. Although the mean showed significant variations from patient to patient, the range offered a more reliable precise measurement. As time went on, quality control in the laboratory developed to become increasingly important. Modern methods provide more accurate results and offer sophisticated techniques for analysis and interpretation.

The Science of Quality Control in the Laboratory

In a broader sense, quality control is a means to ensure that the product quality remains the same or improves. It denotes the construction of control protocols to standardize production processes to achieve consistent quality outputs.

The laboratory's quality control seeks to streamline lab processes and set control measures to detect and rectify discrepancies. The end goal is to minimize errors, which consequently ensures improved results quality.

In that regard, quality control is a measure of precision. It determines how consistent a system is in producing accurate results under varying conditions.

Quality control processes in a laboratory are often conducted at the beginning of every shift as staff interchange. It is also essential to run quality checks after equipment undergoes service or calibration before putting it back into service. This helps determine accurate results before entrusting the equipment to patient use.

 

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Detailed data analysis helps determine how closely measured results align with expected values. Precision indicates how consistently an instrument reproduces the same result for the same sample under identical conditions.

Quality control and quality assurance are both essential components of quality management, but they serve different purposes. Quality assurance focuses on establishing systems and processes that instill confidence that quality requirements will be met. Quality control, by contrast, centers on inspection, testing, and verification to confirm compliance with those requirements.

An effective laboratory quality control system must meet several criteria. It should be easy to use, reproducible across multiple control samples, and stable over extended periods. Minimal vial-to-vial variation is essential; otherwise, measurement system errors may appear as false trends. Stability and resistance to short-term interference are equally important for dependable results.

 

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Detailed analysis can help determine how close output is to an expected value. The precision value determines how consistently the instrument can reproduce the same value, for the same test sample, under the same test conditions.

Quality control and quality assurance are both part of quality management. However, they differ in purpose and application. Quality assurance puts in place mechanisms and systems to instill confidence in management and stakeholders that the output will fulfill all requirements. However, quality control has to do more with inspection, to determine compliance with quality requirements.

A few elements are mandatory for an excellent quality control system. The system must be easy to use and reproduce over many groups of control samples. It must also have minimal vial-to-vial variations. If not, these discrepancies will appear as systemic errors arising from the measurement system. Moreover, its stability should be dependable for extended periods and not susceptible to interferences in the short term.

The Two Main Methods of Quality Control in the Laboratory

There are two primary methods used in laboratory quality control. The first is product and process inspection, which focuses on verifying that both the laboratory process and the final product meet predefined specifications. This includes assessing equipment performance, material suitability, and adherence to standard operating procedures.

The second approach is statistical quality control, a more advanced method that uses statistical analysis, probability, and sampling techniques to monitor and control quality. This method requires defining a representative sample population, analyzing the data, and applying statistical tools such as control charts to identify trends, deviations, and necessary corrective actions.

Quality Control Calculations in the Laboratory

Before performing quality control calculations, laboratories typically collect at least 20 control measurements over a minimum of 10 working days. Longer study periods are often preferred, particularly when methods or conditions change.

The mean is calculated by summing all measured values and dividing by the total number of measurements. For small datasets, a scientific calculator may suffice. For larger datasets, statistical software such as SPSS or SAS provides greater efficiency and analytical capability.

Because the mean reflects accuracy and central tendency, shifts in the mean may indicate systematic errors or process drift.

The standard deviation is another key metric in laboratory quality control. It is calculated by determining the difference between each result and the mean, squaring that difference, dividing by n-1 (where n is the number of samples), and taking the square root. Standard deviation describes the spread of results around the mean and therefore reflects precision.

Since standard deviation varies with concentration, laboratories often use the coefficient of variation (CV). Expressed as a percentage of the mean, the CV provides a more consistent measure of performance across varying concentration ranges.

Digital Solutions and Automation in Quality Control

Digitalization and automation are transforming laboratory quality control by improving efficiency, accuracy, and data integrity. Modern Laboratory Information and Management Systems (LIMS) enable centralized data acquisition, automated result evaluation, and structured documentation of quality control activities.

Automated inspection processes reduce the risk of human error while increasing consistency and throughput. By standardizing workflows and automating repetitive tasks, laboratories can improve traceability and ensure that quality control results are reliably recorded and retrievable.

The integration of sensor technology and cloud-based monitoring systems further enhances laboratory quality control. Connected sensors continuously capture critical parameters—such as temperature, humidity, and pressure—in real time. Cloud platforms allow laboratories to visualize trends, receive alerts and access validated data from anywhere, supporting faster decision-making and proactive risk management.

Quality Assurance and Regulatory Requirements

Laboratory quality control operates within a framework of international quality and regulatory standards. Guidelines such as ISO 17025, Good Laboratory Practice (GLP), and Good Manufacturing Practice (GMP) define requirements for competence, documentation, traceability and data integrity in laboratory processes.

Compliance with these standards requires comprehensive documentation and verifiable proof for supervisory authorities and auditors. This includes calibration records, validation reports, audit trails and documented quality control results.

Regular internal and external audits, along with scheduled equipment calibration, are essential for maintaining a reliable and compliant data foundation. These activities help identify gaps, confirm ongoing compliance, and ensure that laboratory data remains accurate, traceable, and fit for regulatory inspection.

Conclusion

Quality control in laboratories is a crucial element that cannot be overlooked. It is necessary to apply it to both the product and process to improve productivity and maintain product quality.

Every accredited lab should invest in a quality control plan and promote a culture of mandatory compliance to it. Additionally, regular audits to keep the plan in line with the latest standards are also necessary.

Frequently Asked Questions About Laboratory Quality Control

What is laboratory quality control, and why is it important?

Laboratory quality control refers to the procedures and checks used to ensure that test results, measurements, and processes are accurate, reliable and consistent over time. It plays a critical role in protecting data integrity, supporting correct clinical or production decisions, and ensuring compliance with regulatory standards. In sensitive environments such as medical, pharmaceutical, and research laboratories, effective quality control helps prevent errors that could compromise patient safety or product quality.

What is the difference between internal and external quality control in laboratories?

Internal quality control (IQC) involves routine checks performed within the laboratory, such as running control samples at the beginning of shifts, after equipment calibration, or following maintenance. These checks help detect errors in real time and ensure day-to-day consistency.

External quality control (EQC), often referred to as proficiency testing, involves comparing a laboratory’s results with those from external organizations or peer laboratories. External quality control provides independent verification of accuracy and demonstrates overall laboratory competence to regulators and accrediting bodies.

Both internal and external quality control processes are essential for maintaining confidence in laboratory results.

How do quality assurance and quality control differ in a laboratory setting?

While closely related, quality assurance (QA) and quality control (QC) serve different functions in the laboratory.

Quality assurance focuses on the systems, procedures, and documentation that ensure quality requirements will be met consistently. This includes standard operating procedures, training programs, audits, and validation activities.

Quality control, on the other hand, focuses on operational checks and measurements, such as inspections, control samples, and statistical analysis, to verify that results meet defined specifications. Together, QA and QC form the foundation of effective laboratory quality management.

What role do quality management systems play in laboratory quality control?

Quality management systems (QMS) integrate quality control and quality assurance activities into a structured framework. Standards such as ISO 17025, GLP, and GMP define requirements for documentation, traceability, calibration, validation and continuous improvement.

By implementing a QMS, laboratories can streamline workflows, standardize processes and ensure regulatory compliance while improving overall efficiency and data reliability.

What are the main components of an effective laboratory quality control program?

An effective laboratory quality control program typically includes:

  • Use of control samples and reference standards
  • Routine equipment calibration and verification
  • Defined acceptance criteria and control limits
  • Statistical quality control tools, such as control charts
  • Documentation and traceable recordkeeping
  • Regular review of trends and deviations

These components work together to detect errors early and support consistent, reproducible results.

Why is equipment calibration essential for laboratory quality control?

Equipment calibration ensures that laboratory instruments provide accurate and traceable measurements. Over time, instruments may drift due to wear, environmental conditions or usage. Regular calibration helps maintain measurement accuracy, supports compliance with regulatory standards, and provides confidence that laboratory data is fit for its intended use.

How do digital systems improve quality control in laboratories?

Digital tools such as laboratory information and management systems (LIMS), automated inspection processes, and cloud-based monitoring platforms enhance quality control by reducing manual errors, improving data traceability, and enabling real-time visibility of critical parameters. These systems support faster decision-making, simplify documentation and strengthen compliance with quality and regulatory requirements.

How often should laboratories review and audit their quality control processes?

Quality control processes should be reviewed continuously and formally audited on a regular basis, depending on regulatory requirements and laboratory risk profiles. Routine internal audits, combined with external audits and proficiency testing, help ensure ongoing compliance, identify improvement opportunities, and maintain a reliable and defensible quality control system.
Lab & Equipment

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