SOP for Rounding off of Analytical Results

• 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 in 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.

SOP for Rounding off of Analytical Results

OBJECTIVE

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

SCOPE

This Procedure applies to Rounding off 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 worksheet and compare it 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 the 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 an 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 the Certificate of Analysis. However, in the worksheet, the actual observation of analysis shall be specified (for example Less than 50ppm, the color intensity of sample solution is not more than that of standard solution “x” or formation of a specific color to the solution or formation of precipitate).

ABBREVIATION

SOP: Standard Operating Procedure 

QC: Quality Control 

% : Percentage 

ANNEXURE

Nil

REVISION HISTORY

Nil

ALSO READ: SOP for Analytical Data Review