Possible Causes of OOS Results

1. Laboratory Errors

• Improper sample preparation or dilution

• Incorrect weighing or pipetting

• Instrument malfunction or improper calibration

• Wrong method execution or deviation from SOP

• Calculation or transcription errors

2. Method-Related Issues

• Non-validated or poorly validated analytical method

• Inadequate method transfer or training gaps

• Inappropriate chromatographic conditions (e.g., column, mobile phase, gradient)

• Interference from impurities, excipients, or degradation products

3. Sample-Related Issues

• Sample mix-up or mislabeling

• Improper sampling technique (not representative)

• Contaminated sample or sample handling errors

• Stability issues during storage/transport

4. Manufacturing Process Issues

• Improper mixing or blending of raw materials

• Incorrect granulation, drying, or compression parameters

• Inadequate process controls during manufacturing

• Cross-contamination between batches

5. Raw Material/Excipient Issues

• Use of substandard raw materials

• Supplier quality issues

• Variability in excipient properties (e.g., particle size, moisture content)

6. Environmental / Storage Conditions

• Exposure to unsuitable temperature or humidity

• Poor storage conditions of samples or reagents

• Light or oxygen sensitivity leading to degradation

7. Human Errors

• Deviation from SOPs during analysis or manufacturing

• Poor documentation practices (Data Integrity issues)

• Lack of training or awareness

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