Analyze Immediately Within 15 minutes of collection: pH Residual Chlorine Temperature Chlorine Dioxide Dissolved Oxygen (probe) Sulfite note sample collection & analysis times!!!
Topics covered today: pH Temperature Dissolved Oxygen (DO) Residual Chlorine (TRC or CPO)….
pH: what we will cover…. Significance of pH. (data quality) Points to Remember. Lab Chemicals. Good Lab Practices (GLP). Review NJAC Regs. as they pertain to the recording & reporting of data.
What exactly is pH??? Negative log of Hydrogen ion activity. pH above 7: alkaline or basic. pH below 7: acidic. pH = 7 is considered neutral. Di-ionized water saturated with CO 2 has pH = 5.65
Data Quality : a piece a cake! Properly working instrument & clean apparatus. Fresh buffers and reagent rinse water. Hold times met. Correctly calibrated. Proper sample handling. GLP
Data Quality: Calibration Grab: Daily, within 3 hrs. of sample analysis. 2 buffers, bracketed. Mid-range check. Record time, concentration and actual reading of each. For initial calibration, reading must be +/- 0.05 of true value. Recalibrate if difference is greater than +/- 0.2 (applies to 3 hr. check). Discard pH buffer aliquots after each use.
Data Quality: Calibration Continuous: Weekly, unless otherwise stated by SA. Indirect Calibration - basically a grab (as close to electrode as possible); measure within 15 minutes with lab pH meter; compare readings of continuous monitor with lab pH meter. Record info in logbook, sign & date. Direct Calibration (as in grab procedure). - accurate to 0.1, per method (SM 4500-H B). Record time, concentration and actual reading of each. Discard pH buffer aliquots after each use.
Make sure……. Grab pH: meter in good working order (field or hand-held models vs.lab or bench-top models). Continuous monitor: keep probe clean. Calibrate as per method. Maintain calibration & sample collection log. Maintain field data notebook.
Make Sure (continued)- Discard buffers IMMEDIATELY following use - DO NOT re-use! Discard expired buffers! Electrode is OK - not damaged. Stir or swish sample during measurement. Record time of analysis.
Make Sure (continued)- Meters must have accuracy of +/- 0.05 and +/- 0.05 resolution...since pH is temperature-dependent Must be temperature- compensated… or use stand-alone thermometer…
Lab Chemicals…... FRESH buffers! (purchase ready-made or make yourself). Reagent water. Electrode filling solution (if necessary).
Hold Times Pertains to grab pH and indirect calibration for continuous measurement. 0 - 15 minutes - note time of collection & time of analysis!
Good Lab Practices (GLP) Data signed, initialed & dated. Instrument ID & serial number NO pencil! NO white-out! Single-line, date & initial all errors.
Analyze-Immediately parameters Records NJAC 7:18-8.5 - This section pertains specifically to Analyze-Immediately parameters… GENERAL: retain raw data records, quality control data records, chain-of-custody forms, laboratory reports… Storage of data - data must be filed & maintained in an accessible location on lab premises for 1 year after analysis date… Long-term storage: records of analysis must be stored for 5 years after analysis date.
Retain as Records of Analysis Assigned lab ID # or other form of ID date & time of analysis name & signature of person(s) who collected sample name & signature of person(s) who analyzed sample type of analysis performed & DSAM* used (*DSAM=Dept. Sanctioned Analytical Method) results of analysis & raw data generated from analysis
Reporting Results Certified environmental lab name & NJ lab ID number date, time & location of sample collection and sample analysis type of analysis performed and analytical method employed results from analysis name & signature of environmental lab manager or designee per NJ regulations (NJAC 7:18- 2.11(a)1iii)
Summary Dont underestimate the importance of pH. Adhere to NJAC Regulations and approved method. Document-document- document!!!