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SOP for Rounding off Analytical Results

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SOP for Rounding off Analytical Results | Guidelines for Rounding Off as per USP | USP Recommendations on Significant Figures and Rounding |

SOP for Rounding off Analytical Results

1.0 OBJECTIVE:

To establish guidelines for reporting analytical values and rounding off numbers/Digits.

2.0 SCOPE:

SOP for Operating and Calibrating Analytical Balance
This SOP applies to reporting analytical values and rounding off numbers.

3.0 RESPONSIBILITY :

The QC Staff is responsible for: Following the procedure in this SOP.
The Manager-QC is responsible for Ensuring compliance with this SOP.
The Manager-QA is responsible for Ensuring compliance with this SOP.

4.0 ACCOUNTABILITY: Manager-QC

5.0 PROCEDURE for Rounding off Analytical Results:

5.1 After completing the analysis, the analytical chemist shall calculate the analytical result in the test data sheet and compare it with the specified limits in the specifications.
5.2 Report the calculated analytical values in the test data sheet, COAs, and raw data sheets as shown in the table below:
5.3 When reporting results for related substances, disregard limits for unknown impurities and LOD & LOQ limits for known impurities. Do not consider unknown impurities below the disregarding limit.
5.4 If a known impurity is less than the LOD, do not include it in the calculation.
5.5 If the Impurity value is greater than the LOD limit but less than the LOQ, do not include it in the calculation of total impurities and individual impurities.
5.6 Include any known impurity value exceeding the LOQ limit in the calculation of total impurities.
5.7 If the calculated value(s) have more digits after the decimal place than stated in the limit, round off as described below;

5.8 Rounding off shall be done by considering only one digit to the right of the last place in the limit expression, as shown in the illustration below.

  • If the digit is less than 5, discard it and keep the preceding digit unchanged.
  • If the digit is 5 or greater, discard it and increase the preceding digit by one.
  • Limits are fixed numbers and should not be rounded off.

5.9 When the analytical method or test requires quantification, express the analytical result as an observed numerical value.
5.10 When the analytical method or test does not require quantification, express the analytical result as “Conform” or “Does not conform” on the Certificate of Analysis. However, in the test data sheet, specify the actual observation of analysis (e.g., Less than 50 ppm, color intensity of sample solution is not greater than that of standard solution “x,” or formation of specific color or precipitate).

Related SOPs:

6.0 ABBREVIATIONS:

QA Quality Assurance
QC Quality Control
SOP Standard Operating Procedure
NMT Not more than
LOD Limit of Detection
LOQ Limit of Quantitation
COA Certificate of Analysis
LOD Loss on drying”

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