LIMS Requirements for Correct Use of Significant Figures and Rounding for Regulatory Compliance

LIMS in the Modern Laboratory
Oral Presentation

Prepared by E. Askew
Askew Scientific Consulting LLC, 2952 155th Street, Muscatine, Iowa, 52761, United States

Contact Information:; 563-554-9450


Current promulgated rules and methods under 40 CFR part 136 and 40
CFR part 141 require that precise and accurate data be produced by the
laboratory. In turn, this data is then used by regulators at the local,
state and national level to determine if a plant or industry is in
compliance with the Clean Water Act or Safe Drinking Water Act. Though
the identification of significant digits in an analytical result and the
correct rules for rounding them are taught in high school chemistry,
their use in data entry into a LIMS system or the LIMS logic fails many
times to follow these rules. Current EPA documents on rounding and
significant figures are either lacking or out of date and as such the
final regulatory result for the plant or industry may be a violation
enforcement that is not justified. The talk will focus on the basic
rules on significant digits, rounding both manual and machine,
instrument software and regulatory pitfalls. Case study examples will be