The EPA is mandating that my colorimeter be calibrated monthly in order to be used for reporting purposes. It is not practical to send in for calibration monthly. Can this meter still be used for reporting purposes?

Document ID

Document ID TE546

Published Date

Published Date 21/01/2019
Question
The EPA is mandating that my colorimeter be calibrated monthly in order to be used for reporting purposes. It is not practical to send in for calibration monthly. Can this meter still be used for reporting purposes?
Summary
EPA calibration requirements for Pocket Colorimeter
Answer
Method 334.0 and the Pocket Colorimeters meet the requirements. The EPA method states:

10.1.1.2.1. For methods that do not require the preparation of a curve or that use an internal, factory set calibration curve, compare the measured concentration of each standard to the expected value. Each calibration point must be within ± 15% of its expected value. If the internal curve does not meet these criteria, update the internal curve by following the manufacturers’ instructions for generating/inputting a curve. Otherwise, send the meter to the vendor for repair/updating.

After initial verification of the grab sample instrument calibration, the method calls for a periodic analysis of a check standard (at least quarterly, or when the grab sample measurement is used to adjust the calibration of the on-line analyser). It states: The grab sample measured concentration of the calibration check standard must be within ± 15% of the expected value. If this criterion is not met, the analyst must identify and resolve the problem with the grab sample method prior to proceeding with analyses of grab samples to verify the on-line chlorine analyser accuracy.

The method also encourages use of secondary standards (e.g. SpecChecks) for routine calibration checks as follows:
-Analysis of secondary standards is an easy way to verify the spectrophotometer is operating properly for colorimetric methods.
-Analysis of secondary standards does not replace the analysis of aqueous check standards.
-Each secondary standard must be within ± 10% of its expected concentration.

If customers insist on doing a calibration instead of a calibration adjustment, the manual for the PCII does include instructions for entering a user calibration, or editing the factory calibration. Other options include the DR800's, DR900, or the generic 528 nm Pocket Colorimeter II.

Refer to the EPA website for the most current version of Method 334.0 and Hach’s version of the method, which provides the specific instructions for meeting the requirements of Method 334.0.