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TURBIDITY STANDARDS FOR FIELD MEASUREMENTS Mike Lizotte YSI, INC

TURBIDITY STANDARDS FOR FIELD MEASUREMENTS Mike Lizotte YSI, INC. OUTLINE OF PRESENTATION. YSI TURBIDITY SENSORS TYPES TURBIDITY STANDARDS USE OF POLYMER STANDARDS SOURCES OF STANDARDS. YSI TURBIDITY SENSORS. YSI 6026 -- 1995-PRESENT YSI 6136 -- RELEASED IN 2002. YSI TURBIDITY SENSORS.

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TURBIDITY STANDARDS FOR FIELD MEASUREMENTS Mike Lizotte YSI, INC

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  1. TURBIDITY STANDARDS FOR FIELD MEASUREMENTSMike LizotteYSI, INC

  2. OUTLINE OF PRESENTATION • YSI TURBIDITY SENSORS • TYPES TURBIDITY STANDARDS • USE OF POLYMER STANDARDS • SOURCES OF STANDARDS

  3. YSI TURBIDITY SENSORS • YSI 6026 -- 1995-PRESENT • YSI 6136 -- RELEASED IN 2002

  4. YSI TURBIDITY SENSORS YSI 6136 ADVANTAGES • MORE CLOSELY MIMICS HACH 2100AN READINGS IN RATIO MODE • MORE ROBUST CONSTRUCTION

  5. COMPARISON OF TURBIDITY SENSOR READINGS FOR FIELD SAMPLES -- LOW VALUES

  6. COMPARISON OF TURBIDITY SENSOR READINGS FOR FIELD SAMPLES -- HIGH VALUES

  7. COMPARISON OF HACH 2100AN READINGS -- DIRECT (RATIO)VS. DILUTED (NON RATIO) • TRANSPORT SAMPLE TO LAB • READ SAMPLE DIRECTLY IN RATIO MODE • DILUTE SAMPLE BELOW 40 NTU AND READ IN NONRATIO MODE. THEN RECALCULATE TURBIDITY VALUE USING DILUTION FACTOR

  8. COMPARISON OF HACH 2100AN READINGS -- DIRECT (RATIO)VS. DILUTED (NON RATIO)

  9. COMPARISON OF HACH 2100AN READINGS -- DIRECT (RATIO)VS. DILUTED (NON RATIO) • VALUES ARE VERY CLOSE BELOW 20 NTU • ERROR IS CA. 10 % AT 100 NTU • ERROR CAN BE AS HIGH 80 % AT HIGH NTU -- 2200 DIRECT VS. 1230 DILUTED

  10. TYPES OF TURBIDITY STANDARDS • FORMAZIN • POLYMERS

  11. FORMAZIN THREE BASIC SOURCES OF FORMAZIN • USER-PREPARED ACCORDING TO STD. METHODS RECIPE -- HYDRAZINE + HEXAMETHYLENETETRAMINE • DILUTIONS OF 4000 NTU CONCENTRATE • STABLCALTM REAGENTS FROM HACH

  12. USER-PREPARED FORMAZIN • ADVANTAGES -- MOST TRACEABLE STANDARD IF DONE CORRECTLY • PROBLEMS -- HYDRAZINE IS VERY TOXIC AND SHOULD BE HANDLED BY A CHEMIST IN A FUME HOOD. TIME CONSUMING

  13. FORMAZIN FROM DILUTIONS OF 4000 NTU CONCENTRATE ADVANTAGES -- LESS HAZARDOUS THAN USER PREPARED. INEXPENSIVE. PROBLEMS -- CONCENTRATE AND ITS DILUTIONS ARE STILL SOMEWHAT HAZARDOUS. SOME SKILLS AND EQUIPMENT FOR DILUTION ARE NEEDED. SUSPENSIONS ARE SUSCEPTIBLE TO SETTLING.

  14. HACH STABLCALTM FORMAZIN ADVANTAGES -- NO CHEMICAL SKILLS OR EQUIPMENT NECESSARY. LONGER STABILITY THAN DILUTIONS OF 4000 NTU. EXCELLENT DOCUMENTATION. PROBLEMS -- REAGENTS ARE STILL SOMEWHAT HAZARDOUS. SOMEWHAT MORE EXPENSIVE THAN DILUTIONS OF 4000 NTU FORMAZIN. SUSPENSIONS ARE SOMEWHAT SUSCEPTIBLE TO SETTLING.

  15. POLYMER STANDARDS • VARIOUS SOURCES OF POLYMER STANDARDS WHICH SIMULATE FORMAZIN • ONLY AMCO-AEPA STANDARDS FROM ADVANCED POLYMER SYSTEMS ARE LISTED (“APPROVED”) IN STANDARD METHODS.

  16. POLYMER STANDARDS • VARIOUS SOURCES OF POLYMER STANDARDS WHICH SIMULATE FORMAZIN • ONLY AMCO-AEPA STANDARDS FROM ADVANCED POLYMER SYSTEMS (APS) ARE LISTED (“APPROVED”) IN STANDARD METHODS.

  17. ADVANTAGES OF POLYMER STANDARDS • NO CHEMICAL SKILLS OR EQUIPMENT NECESSARY • COMPLETELY NON-TOXIC • NEUTRALLY BUOYANT IN WATER -- SETTLING IS NOT A PROBLEM

  18. DISADVANTAGES OF POLYMER STANDARDS • SIGNIFICANTLY MORE EXPENSIVE THAN FORMAZIN • SUSPENSIONS MUST BE CUSTOM PREPARED USING THE SENSOR TYPE WHICH WILL BE CALIBRATED USING THE POLYMER STANDARD

  19. PREPARATION OF YSI-APPROVED POLYMER STANDARDS • CALIBRATE A YSI TURBIDITY SENSOR AT 0 AND 100 NTU WITH CERTIFIED FORMAZIN STANDARD. • PLACE THE CALIBRATED SENSOR IN THE POLYMER STANDARD AND ADJUST THE TURBIDITY OF THE SUSPENSION BY ADDITION OF CONCENTRATED POLYMER STANDARD OR WATER UNTIL IT READS EXACTLY 100 NTU.

  20. PREPARATION OF YSI-APPROVED POLYMER STANDARDS (CONT.) BOTTLE THE STANDARD AND LABEL AS THE EQUIVALENT OF 100 NTU FORMAZIN.

  21. YSI-APPROVED POLYMER STANDARDS AFTER CALIBRATION OF BOTH 6026 AND 6136 WITH FORMAZIN, SAME YSI-APPROVED POLYMER STANDARD SUSPENSIONS READ DIFFERENTLY WITH THE TWO DIFFERENT YSI SENSORS -- 6026 (1995-PRESENT) AND 6136 (INTRODUCED IN 2002):

  22. YSI-APPROVED POLYMER STANDARDS STANDARD TYPENTU VALUE RELATIVE TO FORMAZIN 6026 6136 LOW 10.0 11.2 MEDIUM 100 123 HIGH 800 1000

  23. SOURCE OF TURBIDITY STANDARDS FOR YSI SENSORS • HACH FORMAZIN -- EITHER DILUTED 4000 NTU CONCENTRATE OR STABLCALTM • POLYMER (AMCO-AEPA) SUSPENSIONS PURCHASED DIRECTLY FROM YSI.

  24. SOURCE OF TURBIDITY STANDARDS FOR YSI SENSORS • NO OTHER SOURCES ARE APPROVED BY YSI. • USE OF STANDARDS FROM ANY OTHER SOURCES IS LIKELY TO RESULT IN SIGNIFICANT LACK OF REPRODUCIBILITY BETWEEN DIFFERENT YSI SONDES OWNED BY THE USGS

  25. TYPES OF TURBIDITY STANDARDS -- NOMENCLATURE • “PRIMARY” VERSUS “SECONDARY” • DESIGNATION IS AGENCY DEPENDENT • STD. METHODS -- ONLY FRESHLY PREPARED FORMAZIN IS “PRIMARY” • USEPA -- VIRTUALLY ALL LIQUID SUSPENSIONS ARE “PRIMARY”.

  26. DIFFERENT POLYMER STANDARDS FOR DIFFERENT YSI TURBIDITY SENSORS

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