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SOP for Rounding off of Analytical Result

  • Rounding of the figure is a mathematical method in which replacing one number with another number to get the approximate and nearby value.
  • The rounding of figures is important because it gives the final reporting results an accurate and easier form.
  • Rounding of figures can be done for both rounding of decimals (e.g. 10.769 rounded to 10.78) and rounding of whole numbers (3350 rounded to 3300). 
  • Mostly in the pharma industry, the final results are calculated either manually or by using validated excel sheets or validated calculators which are prepared in an automated way to give the final results in rounding figures.

OBJECTIVE:
To lay down a procedure for establishing guidelines for reporting of analytical values and rounding off the digits.

SCOPE: 
This Procedure is applicable to Rounding off of Analytical Results at a quality control laboratory. 

RESPONSIBILITY:
Execution: Chemist and above – QC department. 
Checking: Asst. Manager and above – QC department. 


PROCEDURE:
  • After completion of the analysis, the analytical chemist shall calculate the analytical result in the work sheet and compare with the stated limits in the specification. 
  • If the calculated value(s) contains more digits in the decimal place than that in the stated limit, the digits after decimal place shall be rounded off as described below. 
  • Rounding off shall be done by considering only one digit in the decimal place to the right of the last place in the limit expression as shown in the illustration below. 
  • If the digit is smaller than 5, it shall be eliminated and the preceding digit shall remain unchanged 
  • If the digit is greater than or equal to 5, it shall be eliminated and the preceding digit shall be increased by one. 

Illustration of Rounding Numerical Values for comparison with requirements 

Compilations Requirement

Unrounded value

Rounded results

Conforms

Assay limit > 98.0%

97.96%

98.0%

Yes

97.92%

97.9%

No

97.95%

98.0%

Yes

Assay limit < 101.5%

101.55%

101.6%

No

101.46%

101.5%

Yes

101.45%

101.5%

Yes

Limit test < 0.02%

0.025%

0.03%

No

0.015%

0.02%

Yes

0.027%

0.03%

No

Limit test  < 3ppm

0.00035%

0.0004%

No

0.00025%

0.0003%

Yes

0.00028%

0.0003%

Yes

  • When the analytical method or test requires quantification, in such cases, the analytical result shall be expressed as observed numerical value. 
  • When the analytical method or test does not require quantification, in such cases the analytical result shall be expressed as “Conform” or “does not conform” as the case may be on Certificate of Analysis. However, in the work sheet, the actual observation of analysis shall be specified (for example: Less than 50ppm, colour intensity of sample solution is not more than that of standard solution “x” or formation of specific colour to the solution or formation of precipitate). 
ABBREVIATION
SOP : Standard Operating Procedure 
QC : Quality Control 
% : Percentage 

ANNEXURE
Nil

REVISION HISTORY
Nil

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