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Holding Time Calculations

Maximum Holding Times and the “Q” Data Qualifier Code

The approved maximum holding times for specific analytes are listed in the DEP SOP FS 1000 tables.  Any results reported from samples not meeting the holding times specified in those tables must be qualified and reported with the “Q” data qualifier code, per rule 62-160.700, F.A.C. (Table 1 of the DEP QA Rules).  The holding time limits in the DEP SOP tables do not allow for extra time to prepare or analyze samples beyond the maximum times specified.

How to Calculate the Holding Time in Hours or Days

A sample test is completed within the holding time when the sample is prepared and/or analyzed (i.e. “processed”) up to and including, but not exceeding, the last hour or day of the approved holding time that is specified for any processing step (e.g. sample extraction or analysis).  The duration of the holding time must be calculated relative to the sample collection time.

Holding time in hours – Each hour of specified holding time is 60 minutes. Calculate the maximum holding time for the sample using the 60-minute increment for each hour that the sample may be held past the sample collection time before processing must begin. For example, the analytical result for a sample with an 8-hour holding time collected at 9:20 a.m. must be qualified if processing begins after 5:20 p.m. (17:20).

Holding time in days - Each day of specified holding time is 24 hours. Calculate the maximum holding time for the sample using the 24-hour increment for each day that the sample may be held past the sample collection time before processing must begin. For example, the analytical result for a sample with a 7-day holding time collected at 9:00 a.m. on 4/1 must be qualified if processing begins after 9:00 a.m. on 4/8, the seventh day after collection.

Should you need assistance in interpreting holding time criteria for any analyte, and for any other questions about DEP holding-time requirements, please contact the Aquatic Ecology and Quality Assurance Section.

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Last Modified:
March 27, 2019 - 8:46am

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