Calibration of Coulter Counter Guide

Learn Calibration of Coulter Counter SOP with steps, parameters, frequency, and FAQs for accurate particle size analysis.

Calibration of Coulter Counter: Complete SOP Guide

Accurate particle size analysis is critical in quality control laboratories, and proper Calibration of Coulter Counter ensures reliable and reproducible results. This detailed SOP-style guide explains the objective, procedure, parameters, and best practices for calibrating a Coulter Counter effectively.

1. Objective

The purpose of this procedure is to ensure the Calibration of Coulter Counter is performed correctly to deliver accurate, precise, and consistent analytical results.

2. Scope

This SOP applies to the calibration of the Coulter Counter installed in the Quality Control (QC) department and is relevant for all routine calibration activities.

3. Responsibility

• Technical Assistant: Responsible for performing the calibration
• Executive/Manager: Responsible for reviewing and verifying the calibration process

4. Accountability

The Head of Department (HOD) is accountable for ensuring compliance with this SOP and maintaining calibration standards.

5. Calibration Procedure

5.1 Frequency

Calibration should be performed once every three months or as required.

5.2 Initial Setup

• Operate and program the instrument according to the instrument SOP
• Navigate to the SET UP menu using the menu cursor keys

5.3 Parameter Settings

Configure the instrument with the following parameters:

• Orifice Size: 70 µm and 100 µm (alternately)
• Diameter/Length: Enter aperture diameter and orifice tube length
• Setup Mode: Automatic
• Analysis Mode: Sample
• Calibration Mode: New
• Particle Size:
  • Enter latex particle size (number mode)
  • Ensure particle size is ~20% of aperture diameter
  • Example: 2.15 E1 = 21.5 µm
• Size Units: mm

5.4 Graph and Display Settings

• Select FULL RANGE
• X-Axis → Linear Diameter (Lin Dia)
• Y-Axis → Number Difference (Number Diff)
• Blank Subtract → No
• Channels → 256
• Channel Data → No

5.5 Calibration Execution

1. Observe readings as per SOP
2. Adjust upper and lower cursors to align with peak height
3. Press SET UP → Record on calibration line
4. Note the newly displayed Kd factor
5. Press CAL key to finalize calibration
6. Print graph and setup details with the new Kd factor
7. Record observations as per annexure

👉 If calibration results fall outside acceptable limits, follow the deviation SOP.

6. Calibration Materials & Standards

• Standard Solution: CC Standard L5 Polystyrene Latex
• Conductivity Fluid: Filtered Normal Saline
• Dosage:
  • 70 µm aperture → 3 drops / 50 mL
  • 100 µm aperture → 3 drops / 50 mL

Orifice Diameter	Kd Value Limit	Latex Size Limit
70 µm	677 ± 10%	±2% of label claim
100 µm	930 ± 10%	±2% of label claim

8. Abbreviations

• No. – Number
• Lin Dia – Linear Diameter
• Diff – Difference
• mm – Micrometer
• µm (m) – Micron

Why Calibration of Coulter Counter Matters

Proper Calibration of Coulter Counter ensures:

• Accurate particle size measurement
• Reliable QC results
• Compliance with regulatory standards
• Reduced analytical errors

Skipping or improperly performing calibration can lead to incorrect data, affecting product quality and compliance.

Frequently Asked Questions (FAQs)

1. What is Calibration of Coulter Counter?

It is the process of adjusting the instrument to ensure accurate particle size and count measurements.

2. How often should a Coulter Counter be calibrated?

Typically, calibration is done every three months or as per lab requirements.

3. Why is latex used in calibration?

Latex particles provide a known and consistent size standard for accurate calibration.

4. What is the Kd factor?

The Kd factor is a calibration constant used to convert signals into particle size measurements.

5. What happens if calibration fails?

If results are out of limits, corrective action must be taken as per SOP before further use.

6. Why is 20% aperture size used for particles?

This ensures optimal sensitivity and accuracy during measurement.

7. What is the role of conductivity fluid?

It helps maintain proper electrical conditions for particle detection.

8. Can calibration be done manually?

The instrument typically uses automatic calibration mode, but setup requires manual input.

9. What are acceptable Kd limits?

• 70 µm: 677 ± 10%
• 100 µm: 930 ± 10%

10. Why is Calibration of Coulter Counter important in QC?

It ensures product quality, data accuracy, and regulatory compliance.