Overview

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• Source: Microbioz India


• Date: 06 May,2026

In the production of Active Pharmaceutical Ingredients (APIs), especially within the pharmaceutical industry, measuring conductivity is necessary. It is a crucial aspect of the integrity of measurement formulations of water, assurance of the completion of cleaning procedures, and the evaluation of chemical levels. Therefore, conductivity is warranted, and the selection of conductivity sensors is pivotal at each stage of the manufacturing process.

Importance of Conductivity Measurement

When developing APIs, the major goal is to manufacture safe and efficient therapeutic molecules. For this, it is important to obtain pure products, free of any unwanted substances that may hinder post purification processes, or that may be detrimental to the patients.

Conductivity is one of the important indicators in numerous pharmaceutical activities, including:

1. Verification of the Purity of Pharmaceutical Grade Water: Conductivity is used to verify the level of ionic impurities within the water that is used in the processes of formulation.
2. Evaluation of the Effectiveness of Cleaning – in – Place (CIP) and Sterilization – in – Place (SIP) :
3. Conductivity checks if the cleaning solutions are effective and residues are destroyed.
4. Determining the Level of Phase Separation and Concentration of Chemicals: It offers excellent control of the level of concentration at different stages of the process.

Selecting the Right Conductivity Sensor

Choosing the appropriate conductivity sensor is vital for accurate readings. Conductivity sensors are categorized into two main types: contacting (with electrodes in direct contact with the sample) and inductive (operating without electrodes).

Key Selection Criteria

Conductivity Range:

1. Low Conductivity: The range for pharmaceutical waters samples is 0.001 – 2,000 μS/cm.
2. Medium Conductivity: The range for buffer formulations and CIP/SIP processes is 0.02 – 500 mS/cm.
3. High Conductivity: The range for chemical concentration control and phase separation is 0 – 2,000 mS/cm.
4. Cell Constant: Cell Constant shows the spacing plus area preference ratio of the electrodes and is a geometric factor in the cell. Dedicated constant for low conductivity is high (0.1cm^-1) while low cell constant is required for medium and high conductivity measurements.
5. Temperature Considerations: Conductivity is influenced and determined by temperature, hence the choice of a sensor integrated with a temperature probe is crucial. This assures temperature compensations and measurements become more accurate for adherence to standards such as the DS 645 and DS 1644.
6. Construction Materials: Materials such as 316L stainless steel are the most suitable sanitary materials. For sensor longevity in corrosive environments, PEEK or PFA materials are preferred.
7. Sensor Length and Fitting: The length and fitting of a sensor is determined by the measurement needs and extended to the most optimal point in the process in order to provide a comprehensive interpretation of the process.  Fittings such as NPT, DN, and Tri -Clamp as well as lengths of differing measurements are available.

Conductivity Measurements Across API Production Steps

Production of Pharmaceutical Waters (Low Conductivity)

Conductivity measurement is vital for controlling ionic impurities in pharmaceutical grade waters. Continuous monitoring through online sensors is recommended to eliminate contamination risks associated with grab sampling.

An example of a suitable sensor is the UniCond 2-E, which features Plug and Measure functionality and an integrated measuring circuit.

CIP/SIP Processes and Formulation (Medium Conductivity)

In CIP processes, conductivity measurements confirm the required strength of cleaning liquids and ensure no residues remain.

A 4-electrode sensor, such as the InPro 7100i, is ideal due to its minimal polarization effects and reduced susceptibility to fouling, ensuring reliable measurements.

Phase Separation and Chemical Concentration Control (High Conductivity)

Conductivity sensors are crucial in phase separation processes, where readings indicate when to interrupt flow and allow for optimal separation. The InPro 7250 inductive sensor, designed with no wetted metal parts, offers excellent chemical resistance and is suitable for aggressive environments.

Conclusion:

Measuring conductivity, in this sector, remains a key concern to ascertain the safety and quality of the final product. Pharmaceutical manufacturers are enabled to ensure quality and reliability by tailoring their sensor selection based on conductivity range, temperature, construction, as well as process safety concerns. Consequently, it assists the suppliers in delivering safe medication and in enduringly observing the standards.

About METTLER TOLEDO:

METTLER TOLEDO is a leading global manufacturer of precision instruments. The Company is the world’s largest manufacturer and marketer of weighing instruments for use in laboratory, industrial and food retailing applications. The Company also holds top-three market positions for several related analytical instruments and is a leading provider of automated chemistry systems used in drug and chemical compound discovery and development. Additional information about METTLER TOLEDO is available at www.mt.com.

Visit us: www.mt.com/pro

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