OWML: QA/QC

Quality Assurance/Quality Control Manual: Ohio Water Microbiology Laboratory

Laboratory water

The OWML has three types of laboratory water:

1. Type III deionized water (“deionized water”) produced from City of Columbus tap water for general laboratory use.  The deionized water unit and tap are stored in the warehouse.  The system is described in Francy and others (1998).  The vendor changes the cation and anion columns, moves forward the standby mixed-bed column, installs a new standby tank, and changes the carbon filter when the red service light illuminates.  Maintenance checks are recorded in the LIMS.
    
2. Reagent-grade water produced using a Millipore MilliQ system (“MilliQ water”).  Deionized water is used as source water for the MilliQ system.  Reagent water is used for cultivation media and additives (mTEC, MI, mEI, antibiotic stocks, and others) as well as for preparation of reagents for sensitive procedures (elutions, PCR, hybridization, and others).  The MilliQ cartridges are changed by OWML laboratory personnel when the service light blinks and the display message reads “EXCH. CARTRIDGES.”  Indicate the date of cartridge change in the LIMS.
    
3. Deionized water is stored in a laboratory carboy (“stored water”) and used for rinsing of dishware and other supplies. 

A variety of quality-control checks are routinely done on the three types of water and may differ depending on the type of water. Acceptance criteria are listed in table 2. For deionized water, two levels of acceptance criteria are listed—(1) a warning level wherein the system is inspected and constituents are retested and (2) a shut-down level.  For MilliQ water, only a shut-down level is listed in table 2.  For stored water, if criteria are not met, the container is cleaned out, refilled, and retested.

• Quarterly checks of specific conductance and turbidity are done on all three types of water and recorded in the LIMS.  Instructions for performing this check are in the back of the equipment QA/QC logbook.
   
• Quarterly checks of bacterial growth are done on the MilliQ water and recorded in the LIMS. Instructions for performing this check are in the back of the equipment QA/QC logbook.
   
• A blank of deionized water is submitted to the National Water Quality Laboratory (NWQL) annually and analyzed for low level nutrients (Schedule 1217), and total-organic carbon (Labcode 114), and the results are recorded in the LIMS. We no longer analyze a blank for trace elements and low-level major ions because the need for these low-level analyses is project specific.
   
• The stored deionized water carboy is to be emptied completely and cleaned with Liquinox and water every other week.  Record cleanings in the LIMS.

Table 2.  Acceptance criteria for laboratory water quality-assurance checks[Adopted from USEPA (1978), APHA (1998), and ASTM (1999); NA is not applicable; constituents highlighted in gray are no longer required tests]