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OWML: QA/QC

Quality Assurance/Quality Control Manual: Ohio Water Microbiology Laboratory

 

Laboratory water
The Ohio Water Microbiology Laboratory (OWML) has two 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 Shaffer (2008).  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 (modified mTEC, MI, mEI, antibiotic stocks, and others) as well as for preparation of reagents for sensitive procedures (elutions, PCR, 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.

A variety of quality-control checks are routinely done on the two 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. 

  • Quarterly checks of specific conductance and turbidity are done on both types of water and recorded in the LIMS.  Instructions for performing this check are in Appendix A1.
     

  • Quarterly checks of bacterial growth are done on the MilliQ water and recorded in the LIMS. Instructions for performing this check are in Appendix A1.
     

  • 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 3211), 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.

 

Table 2.  Acceptance criteria for laboratory water quality-assurance checks. [Adopted from USEPA (1978), APHA (2005), and ASTM (1999); NA is not applicable]

 

DEIONIZED

MILLIQ

ACTION

warning

shut down

shut down

Specific conductance (ms/cm)

3

5

2

Turbidity

1

5

1

Heterotrophic plate count (colonies/mL)

NA

NA

<1

Total organic carbon (mg/L)

0.5

10

NA

Nutrients individual (mg/L)

0.1

1

NA