Quality Assurance (ACRR) Matrix
Contents
1. 8 ORP Oxidation Reduction Potential Sensors Noble Metal Electrode Quality Assurance Actions Documentation Actions Data Quality Aspect Accuracy Bias Precision Lack of interfer ence or contamina tion Affect Control act to influence the outcome Clean electrode with aqua regia Tip OR1 if needed Use submersible equipment for in situ measurements Conduct flowthrough measurements in oxygen impermeable airtight equipment Use consistent procedures under same conditions Avoid prolonged exposure of probe to hydrogen sulfide Avoid moving probe from Zobell s solution into iron rich waters Be aware of the effects of chromium vanadium and other ions that are stronger reducing agents than hydrogen or platinum Conduct one point accuracy check with standard Zobell s Solution Tip OR2 at room temperature before and after field use Repeat measurements 3 5 times after the reading has stabilized under controlled non changing environ ment in the lab during every calibra tion or accuracy check event Record the type of reference elec trode being used the solution s tem perature the observed mV potential of the Zobell s solution emf and the looked up mV potential of the refer ence electrode Eref Results of the 3 5 measurements after stabilization Check Test to evaluate or verify Record Keep everything documented Report Communicate the data quality indicator2. Calculate the difference in mV between Eh theoretical value and the observed Eh emf plus Eref in the Zobell s solution Compute the standard deviation of the 3 5 values and report in measure ment units Tip OR3 ORP Sensors Tips and Comments Oxidation reduction potential ORP a k a Reduction Oxidation Redox potential Eh can delineate qualitatively strong redox gradients for example those found in stratified lakes and rivers with an anaerobic zone in an oxidized surface flow that becomes anaerobic after passing through stagnant organic rich systems and in mine drainage discharges GS nfm 6 5 p 18 Tip OR1 To prepare the aqua regia mix 1 volume concentrated nitric acid with 3 volumes of concentrated hydrochloric acid Tip OR2 Standard Zobell s Solution can be prepared in the lab periodically by a skilled analyst Tip OR3 Precision can be reported as 1 standard deviation SD or as 2 relative percent difference RPD or as 3 relative standard deviation RSD a k a coefficient of variations CV depending on the number of repeated measurements and the requirements of the data management system or the Program
3. s instructions and use only their recommended standards Tip TU1 Ata minimum conduct a three point calibration in the lab using freshly diluted standards at zero mid range and high end of expected envi ronmental range at room temperature before deployment Conduct a two point calibration in the field at min and max of range at stream temperature during every maintenance event if needed Use consistent procedures under same conditions Use consistent procedures under same conditions Clean probes Clean probes often treat with anti foul ing agents adjust deployment duration or maintenance intervals to local condi tions verify functionality and correct parking of wipers Conduct a two point accuracy check in the lab using manufacturer s verification standards at zero and at high end of environmental range within 24 hours of trip s end Conduct a one point accuracy check in the field using manufacturer s verification standards at mid range value at stream temperature before measurements at each site Run periodic comparisons with other methods Conduct a three point accuracy check in the field using manufacturer s verifica tion standards at min mid max values of range at stream temperature during every maintenance event before and after cleaning Conduct a three point accuracy check in the lab using manufacturer s verifica tion standards at min mid max values of range at room tempera
4. a percentage by different terms such as percent bias percent accuracy or relative percent error RPE All of these terms mean the same thing the difference of an Instrument s reading from the known value expressed as percent of the known value Tip A4 Precision can be reported as 1 standard deviation SD or as 2 relative percent difference RPD or as 3 relative standard deviation RSD a k a coefficient of variations CV depending on the number of repeated measurements and the requirements of the data management system or the Program Tip A5 Photographic records of fouling and inspection records should be kept with all data files and may be used to disqualify data Tip A6 Faulty temperature sensor will invalidate all DO salinity specific conductivity pH data and depth data Tip A7 Faulty conductivity sensor will invalidate all DO salinity specific conductivity and depth data Comment A1 This may be relevant only to DO and pH Comment A2 Many Accuracy checks and all Precision checks cannot be performed in the Cal mode Comment A3 In a few cases you can test a diluted sample but dilution is meaningless and may alter the tested property for most vital signs 2 Temperature Sensors Thermistor or RTD rip T1 Quality Assurance Actions Documentation Actions Data Quality Aspect Precision Lack of interfer ence or contami nation Affect Control act to influence the outcom
5. e g within 0 1 degrees C for thermistors resolution may not be relevant to characteristics other then temperature and 6 the orientation of the sonde e g horizontal this is very important for depth measurements including measurements for vertical profiles and Some cells will contain this set in reference to periodic plus another set for annual Continued on Reverse Continued from Front Assumptions All calibration and quality checks records include Instrument ID Date Time and Operator s name and these records are effectively linked to the Project the Location etc Records of sensor s operating parameters e g cell constant mV etc recorded per manufacturer s instructions are also included All DO probes also contain a thermistor but not all of them are associated with a barometer Compensations for barometric pressure and salinity are done per specific protocol s instructions All conductivity and pH probes also contain a thermistor and have a built in automatic temperature compensation ATC capability compensation algorithms may vary in level of sophistication e g some pocket instruments may simply correct the reading by 2 for each degree C All monitoring results are reported after compensation for temperature salinity and atmospheric pressure as relevant salinity is often calculated from conductivity sensors output Depth sensors are always situated at the center of the s
6. percent of standard s true value whichever is higher Report bias Instrument drift i e differ ence from known true value of Stan dard expressed either in measurement units or as percent of Standard s true value whichever is higher Compute the standard deviation of the 3 5 values and report in measurement units Tip DO6 Compute the standard deviation of the 3 5 values and report in measurement units Tip DO6 Dissolved Oxygen Sensors Tips amp Comments Tip DO1 Prepare the Zero DO solution fresh each day by dissolving 1 gram sodium sulfite and a few crystals of cobalt chloride in 1 liter deionized water Tip DO2 Powering off may cause loss of calibration in some instruments check manufacturer s instruction and avoid powering off between sites if needed Tip DO3 Verify that the built in thermistor has been certified within the last 4 months Accuracy of barometers needs to be checked once a year Tip DO4 Methods include excitation fluorescence and recording of quenching either of the intensity or of the lifetime of the fluorescence signal Probe brand names include LDO ROX ODO RDO OPTODE OPTRODE and D OPTO list updated 7 24 09 Tip DO5 A two point calibration at zero and 100 saturation is recommended only if the sensor will be used in anoxic or low oxygen environments Tip DO6 Precision can be reported as 1 standard deviation SD or as 2 relative percent differ
7. 3 Turbidity sensors often report negative values in crystal clear waters this is due to traces of turbidity in the zero calibration standard Tip TU4 Precision can be reported as 1 standard deviation SD or as 2 relative percent difference RPD or as 3 relative standard deviation RSD a k a coefficient of variations Y CV depending on the number of repeated measurements and the requirements of the data management system or the Program Tip TU5 Inspection records and or pictures may be used to disqualify data Photographic records of fouling on and around the sensors is extremely useful for data interpretation and QA and must be kept with the data files 7 Depth Sensors Pressure Transducers Non vented or Vented Tip DE 1 Quality Assurance Actions Documentation Actions Data Quality Aspect Accuracy Bias Precision Lack of interfer ence or contamina tion Affect Control act to influence the outcome Conduct one point calibration Tip DE2 at the site at ambient atmospheric pres sure in air at ambient temperature at the intended sonde orientation before each measurement Tip DE3 Conduct one point calibration Tip DE2 at the site at ambient atmospheric pres sure in air at ambient temperature at the intended sonde orientation before each deployment Tip DE4 Use consistent procedures under same conditions Use consistent procedures under same conditions Keep the depth senso
8. H2 Conduct a three point accuracy check at pH 4 7 and 10 at stream temperature during every maintenance event before and after cleaning Conduct a two point accuracy check at pH 7 and 10 at room temperature within 24 hrs of retrieval before and after cleaning Repeat measurements 3 5 times after the reading has stabilized under con trolled non changing environment in the lab during every calibration or accuracy check event Repeat measurements 3 5 times after the reading has stabilized under con trolled non changing environment in the lab during every calibration or accuracy check event Run fouling comparison test Measure stream water in situ or in bucket before and after cleaning the probe For each pH record instrument reading before adjustment temperature of stan dard and true value of standard For each pH record instrument reading before adjustment temperature of stan dard and true value of standard Results of the 3 5 measurements after stabilization Results of the 3 5 measurements after stabilization Pre cleaning inspection and photograph ic records of fouling Instrument readings before and after probe fouling removal Check Test to evaluate or verify Record Keep everything documented Report Communicate the data quality indicator Report bias maximal Instrument drift or difference from true value expressed in measurement units Report bias Maxim
9. Quality Assurance ACRR Matrix QA Checklist for Calibration Quality Checks and Record Keeping methodsand data comparabili boat to Ensure that Data Are of Known and Documented Quality April 19 2010 acwi gov methods This page intentionally left blank Quality Assurance Matrix Affect Check Record Report Scope The Matrix provides recommendations for the minimal array of actions deemed necessary for collection of usable data of known and documented quality The Matrix is focused on the quality of the measurement i e the performance of the measurement system Issues related to what the Result represents in the monitored environment are not included please see the companion document Sensors Deployment Guide This matrix should be used in conjunction with not instead of the sensor s User Manual and the Program s Standard Operating Procedures SOP Users of turbidity sensors should also consult the Turbidity Addendum a companion document to this Matrix available at the ASW website http watersensors org Sources The structure of this matrix with its breakdown into actions to Affect Check Report and Record the quality of monitoring data was developed in 2002 by Dr Revital Katznelson for the California State Water Resources Control Board GS USGS National Field Manual various chapters and Wagner et al 2006 TX TCEQ SWQM Program manual ampm_011 and Chapter 8 2007 NR National Estuarine Researc
10. acy check at 100 air saturation at room or ambient temperature at every maintenance event and within 24 hrs of retrieval before and after cleaning Repeat measurements 3 5 times after the reading has stabilized under con trolled non changing environment in the lab during every calibration or accuracy check event Repeat measurements 3 5 times after the reading has stabilized under con trolled non changing environment in the lab during every calibration or accuracy check event Run fouling comparison test Measure stream water in situ or in bucket before and after cleaning the probe Documentation Actions Record Keep everything documented Temperature and atmospheric pressure Tip DO3 Previous Page Instrument DO reading in mg L and looked up DO saturation in mg L at that temperature and atmospheric pressure Temperature and atmospheric pressure Tip DO3 Previous Page Instrument DO reading in mg L and looked up DO saturation in mg L at that temperature and atmospheric pressure Results of the 3 5 measurements after stabilization Results of the 3 5 measurements after stabilization Pre cleaning inspection and photograph ic records of fouling instrument readings before and after probe fouling removal Report Communicate the data quality indicator Report bias Instrument drift i e differ ence from known true value of stan dard expressed either in measurement units or as
11. al instrument drift or difference from true value expressed in measurement units Compute the standard deviation of the 3 5 values and report in measurement units Tip pH3 Compute the standard deviation of the 3 5 values and report in measurement units Tip pH3 pH Sensors Tips and Comments Tip pH1 For pH measurements of low conductivity waters obtain low ionic strength buffers Tip pH2 Powering off may cause loss of calibration in some instruments check manufacturer s instruction and avoid powering off between sites or re calibrate if needed Tip pH3 Precision can be reported as 1 standard deviation SD or as 2 relative percent difference RPD or as 3 relative standard deviation RSD a k a coefficient of variations Y CV depending on the number of repeated measurements and the requirements of the data management system or the Program 6 Turbidity Sensors Light Scattering Quality Assurance Actions Documentation Actions Data Quality Aspect Accuracy Bias Precision Lack of interfer ence or contamina tion Affect Control act to influence the outcome Follow manufacturer s instructions and use only their recommended standards Tip TU1 At a minimum conduct a three point calibration in the lab using freshly diluted standards at zero mid range and high end of expected environmental range at room temperature before each trip Tip TU3 Follow manufacturer
12. alues and report in measurement units Tip SP4 Compute the standard deviation of the 3 5 values and report in measurement units Tip SP4 Lack of interfer ence or contami nation Clean probes Clean probes treat with anti fouling agents adjust deployment duration or maintenance intervals to local conditions Run fouling comparison test Measure stream water in situ or in bucket before and after cleaning the probe Pre cleaning inspection and photographic records of fouling Instrument readings before and after probe fouling removal Specific Conductance Sensors Tips amp Comments Tip SP1 It may be beneficial to conduct calibrations and accuracy checks at 25 C even if the sensor has automatic temperature compensation Tip SP2 Always rinse sensors twice with standard prior to performing checks and calibrations Tip SP3 Calibrating linear conductivity sensors is best done with a strong conductivity signal i e 1 000 uS cm or higher above this value choose a standard that is close to your expected values Tip SP4 Precision can be reported as 1 standard deviation SD or as 2 relative percent difference RPD or as 3 relative standard deviation RSD a k a coefficient of variations CV depending on the number of repeated measurements and the requirements of the data management system or the Program 4A Dissolved Oxygen Sensors Electro chemical Quality Assurance Actions Docum
13. d by working values Comment A3 the instrument as determined by holding range a lint free cloth over the optical sensor and recording the turbidity Validity Take your measurement only after the Observe reading the time length will be Several readings that move both up and Narrative response reading stabilizes short for some probes and few minutes rate for others Program the device to log a measure ment after sufficient time Correct Have the scribe call the result back to the If results were also logged automatically Number of matches and number of Calculate match i e the number of ness instrument reader and verify they entered compare data captured on field data mismatches matching result pairs expressed as a the correct number into the correct box in sheet to same data in the logger file percentage of all result pairs the data sheet General Tips amp Comments Tip A1 The word compensation is used here for all kinds of readings adjustments for specific temperature pressure or salinity The word correc tion is only used for adjustments of Results to correct for fouling and or drift error Tip A2 Corrections for fouling and drift error are not within the scope of this matrix and users should seek further guidance In any case if the dataset has been corrected for fouling or drift it should be communicated clearly Tip A3 Measurement bias or the extent of inaccuracy is often reported as
14. dings before and after probe fouling removal Report Communicate the data quality indicator Report bias Instrument drift i e differ ence from known true value of Stan dard expressed either in measurement units or as percent of Standard s true value whichever is higher Report bias Instrument drift i e differ ence from known true value of Stan dard expressed either in measurement units or as percent of Standard s true value whichever is higher Compute the standard deviation of the 3 5 values and report in measurement Compute the standard deviation of the 3 5 values and report in measurement units Dissolved Oxygen Sensors Tips amp Comments Tip DO1 Prepare the Zero DO solution fresh each day by dissolving 1 gram sodium sulfite and a few crystals of cobalt chloride in 1 liter deionized water Tip DO2 Powering off may cause loss of calibration in some instruments check manufacturer s instruction and avoid powering off between sites if needed Tip DO3 Verify that the built in thermistor has been certified within the last 4 months Accuracy of barometers needs to be checked once a year Tip DO4 Methods include excitation fluorescence and recording of quenching either of the intensity or of the lifetime of the fluorescence signal Probe brand names include LDO ROX ODO RDO OPTODE OPTRODE and D OPTO list updated 7 24 09 Tip DO5 A two point calibration at zero and 100 satura
15. e Take your measurement only after the reading stabilizes Take your measurement only after the reading stabilizes Use consistent procedures under same conditions Use consistent procedures under same conditions Clean probes Clean probes Comment T1 Check Test to evaluate or verify Field thermometer and sonde thermistor Conduct three point accuracy check in the lab at the minimum mid value and maximum of the expected range once per year using NIST certified thermom eter Tip T2 with 0 1 C Tip T3 resolution Tip T4 Sonde thermistor Conduct three point accuracy check at min mid max values of expected range using a NIST certified thermometer in the lab before leaving for deployment Tip T5 Conduct one point accuracy check against the field ther mometer in the field at stream tempera ture before installation and during every maintenance event Conduct one point accuracy check in the lab at room temperature using a NIST certified thermometer immediately after retrieval Repeat measurements 3 5 times after the reading has stabilized under controlled non changing environment in the lab and during every calibration or accuracy check event Repeat measurements 3 5 times after the reading has stabilized under controlled non changing environment in the lab and during every calibration or accuracy check event Record Keep everything documented Average of three repeated meas
16. e or verify Record Keep everything documented Report Communicate the data quality indicator Record the ambient barometric pressure Report bias Instrument drift i e differ ence from known true atmospheric pressure expressed either in measure ment units or as percent of known true atmospheric pressure whichever is Report bias Instrument drift i e differ ence from known true atmospheric pressure expressed either in measure ment units or as percent of known true atmospheric pressure whichever is higher Compute the standard deviation of the 3 5 values and report in measurement units Tip DE5 Compute the standard deviation of the 3 5 values and report in measurement units Tip DE5 Depth Sensors Tips and Comments Standard non vented pressure transducers a k a depth sensors have an opening to the water column on one side and vacuum on the opposite side they do not sense the atmospheric barometric pressure and their measurement results must be post processed to correct for barometric pressure at each point in time However they can be deployed anywhere for continuous monitoring without a cable Vented pressure transducers a k a level sensors have an opening to the water column on one side and an opening to the atmosphere on the opposite side they keep sensing the atmospheric barometric pressure and subtracting it from the total barometric plus hydrosta
17. ence RPD or as 3 relative standard deviation RSD a k a coefficient of variations CV depending on the number of repeated measurements and the requirements of the data management system or the Program 5 pH Sensors Hydrogen lon Electrode Quality Assurance Actions Documentation Actions Data Quality Aspect Accuracy Bias Precision Lack of interfer ence or contamina tion Affect Control act to influence the outcome Conduct two point calibration in the lab w Standard Buffers at pH 7 and pH 10 or pH 4 at room temperature before each trip Conduct two point calibration in the field at pH 7 and pH 10 or pH 4 at stream temperature before measurements at each site Tip pH1 Calibrate after Power Off On if needed Tip pH2 Conduct a two point calibration in the lab at pH 7 and pH 10 or pH 4 at room temperature before each deployment Conduct a three point calibration in the field at pH 4 7 and 10 at stream temperature during every maintenance event if needed Use consistent procedures under same conditions Use consistent procedures under same conditions Clean probes Clean probes treat with anti fouling agents adjust deployment duration or maintenance intervals to local conditions Conduct a two point accuracy check in the lab w standard buffers at pH 7 and pH 10 or pH 4 at room temperature within 24 hours of trip s end and after Power Off On if needed Tip p
18. entation Actions Data Quality Aspect Accuracy Bias Precision Lack of interfer ence or contamina tion Affect Control act to influence the outcome Conduct a two point calibration in the lab at zero Tip DO1 and at 100 air or water saturation at room temperature before each Trip Conduct a one point calibration in the field at 100 satura tion at ambient temperature before first measurement of each monitoring day Re calibrate if the elevation change be tween sites is gt 500m Re calibrate after Power Off On if needed Tip DO2 Conduct a two point calibration in the lab at zero Tip DO1 and at 100 air or water saturation at room temperature before each deployment Conduct one point calibration in the field at 100 air or water saturation during every maintenance event if needed at ambient field temperature Use consistent procedures under same conditions Use consistent procedures under same conditions Clean probes Clean probes adjust deployment dura tion or maintenance intervals to local conditions Check Test to evaluate or verify Conduct a one point accuracy check in the field at 100 air or water satura tion at ambient temperature after each site i e before the next site Conduct a one point accuracy check in the lab at 100 air or water saturation at room temperature within 24 hrs of monitor ing day s end and after Power Off On if needed Tip DO2 Run pe
19. h Reserve s NERR System Wide Monitoring Program SWMP SOP for the YSI 6 Series Sondes PD An experienced State Monitoring Program operator in California personal communication no formal protocol WR the QA officer for a volunteer monitoring Program in California personal communication no formal protocol Various Users Manuals and other guidance documents from sensors manufacturers Modes Attended discrete measurements each measurement is recorded manually into a data sheet or the readings of all sensors are logged as one discrete sample Unattended continuous or time series measurements the Sonde is programmed for automatic measurements and data logging at specified intervals then deployed for a given time period and then retrieved for downloading of the logged data as a deployment episode file This mode also includes real time transmission of the data telemetry For Calibration Actions to Affect and Accuracy Checks Actions to Check Each set of the final recommendations should include reference to all relevant items among the following 1 the number of points e g 2 point calibration 2 the value of each point e g zero and a value above the environmental range 3 the frequency and timing e g once a month or immediately after deployment 4 the temperature of the Standard e g 25 C or middle of environmental range this is not relevant to temperature sensors 5 the resolution
20. heck with Standards at min mid max values of ex pected range plus a zero check in air at room or field temperature within 24 hrs of retrieval and at every maintenance event before and after cleaning Repeat measurements 3 5 times after the reading has stabilized under controlled non changing environment in the lab during every calibration or accuracy check event Repeat measurements 3 5 times after the reading has stabilized under controlled non changing environment in the lab during every calibration or accuracy check event Record Keep everything documented Temperature of standard instrument con ductivity reading temperature compensa tion factor if needed and true value of standard Temperature of standard instrument con ductivity reading temperature compensa tion factor if needed and true value of standard Results of the 3 5 measurements after stabilization Results of the 3 5 measurements after stabilization Report Communicate the data quality indicator Report bias Instrument drift i e dif ference from known true value of Standard expressed either in measure ment units or as percent of Standard s true value whichever is higher Report bias Instrument drift i e dif ference from known true value of Standard expressed either in measure ment units or as percent of Standard s true value whichever is higher Compute the standard deviation of the 3 5 v
21. ias Bias is computed for each standard as the percent differ ence between readings before calibration and readings at the same range after calibration Compute the standard deviation of the 3 5 values and report in measurement units Tip TU4 Compute the standard deviation of the 3 5 values and report in measurement units Tip TU4 Calculate fouling drift as the percent difference between the calibrant reading of the uncleaned sensor and the cleaned sensor Turbidity Sensors Tips and Comments The QA Matrix refers only to dynamic turbidity sensors where the sample moves over the sensor Tip TU1 Because of the immense variability in the light scattering properties of natural waters there is no universal standard for turbidity that can represent a true value Moreover there is a huge variability in turbidity sensors structure performance and response to various light scattering par ticles in water It is important to use the manufacturers standards to achieve the specified performance of the sensor Please see the Turbidity Adden dum document for more information Tip TU2 Turbidity sensors vary widely in their light source detectors angles and number of detectors and light sources Each combination of these factors is associated with a specific technology designated measurement unit that must be used for reporting turbidity values Please see the Turbidity Addendum document for more information Tip TU
22. ndard deviation SD or as 2 relative percent difference RPD or as 3 relative standard deviation RSD a k a coefficient of variations CV depending on the number of repeated measurements and the requirements of the data management system or the Program Comment T1 Assumption Temperature sensors are less impacted by fouling than other sensors 3 Specific Conductance Sensors Conductivity Cell Data Quality Aspect Accuracy Bias Precision Quality Assurance Actions Documentation Actions Affect Control act to influence the outcome Conduct one point calibration in the lab at a value in the middle of anticipated en vironmental range at room temperature Tips SP1 SP3 before each trip Conduct two point calibration in the field at values that bracket expected range at stream temperature before first use of the day Make sure the probe is properly hydrated before calibration and before each use assure sufficient voltage Conduct two point calibration in the lab at zero and at value higher than expected range at room temperature before deployment and at every maintenance event if needed Use consistent procedures under same conditions Use consistent procedures under same conditions Check Test to evaluate or verify Conduct a one point accuracy check in the lab at a mid range value at room temperature Tip SP2 within 24 hours of trip s end Conduct three point accuracy c
23. onde s radial cross section This should be verified with the manufacturer For Attended monitoring there is no time for buildup of a fouling layer during the Trip Acknowledgements A unique public private partnership worked on this document and included the following members e Revital Katznelson PhD Contract lead e Dan Sullivan USGS Workgroup co chair e Gayle Rominger YSI Inc Workgroup co chair e Chuck Spooner USEPA National Monitoring Council co chair e Chuck Dvorsky Texas CEQ e Mike Sadar Hach Co e Cristina Windsor In Situ e Mike Cook and Rob Ellison YSI Inc e Janice Fulford USGS e Jason Harrington Greenspan Analytical A review board provided invaluable feedback and included e Eva DiDonato and Pete Penoyer National Park Service e Mario Tamburri Alliance for Coastal Technologies e Jami Montgomery USEPA e Rick Wagner Andy Ziegler and Eric Vowinkel USGS e Eli Greenbaum Oak Ridge National Laboratory e Tamim Younos Virginia Tech University 1 General All Sensors Quality Assurance Actions Documentation Actions Data Quality Aspect Operator s compe tence Accuracy Bias Precision Lack Extent of interfer ence or contamina tion Affect Control act to influence the outcome Train refresh supervise Use certified non expired Standards for calibration and accuracy checks Calibrate the instrument at the project s prescribed values and intervals and under the prescribed c
24. onditions Calibrate the instrument after every service event and after instrument has been subject to an impact e g during transport or deployment Avoid switching the power off or discon necting the sensor from its display unit between sites Use consistent procedures under same conditions always wait for the reading to stabilize Clean the probe before and after each use and never let it dry dirty promptly wash off any Standard materials used for calibrations and accuracy checks protect sensors from harmful liquids or vapors Check Test to evaluate or verify Run proficiency tests review work products Compare previous lot batch of standards with new lot with a high resolution instru Conduct accuracy checks at the project s prescribed values and intervals and under the prescribed conditions Conduct and accuracy check after every service event and after the instrument has been subject to an impact e g dur ing transport or deployment Check accuracy after turning the instru ment on again Comment A1 Repeat measurements often i Repeat measurements 3 5 times after the reading has stabilized under con trolled non changing environment in the lab during every calibration or accuracy check event ii Repeat field measurements at each site point in at least 2 sites per trip Comment A2 In situ Measure in stream before mov ing sensor or measure in bucket with stream water then mo
25. r s port unob structed at all times Vented keep vent and inner chamber dry and watertight Tip DE6 Keep the depth sensor s port unobstruct ed at all times clean it immediately after retrieval coat it with anti fouling paint if needed Vented keep vent and inner chamber dry and watertight Tip DE6 Conduct one point accuracy check at the site at ambient atmospheric pressure in air at ambient temperature at the field use sonde orientation at the site visit s Conduct one point accuracy check at the site at ambient atmospheric pres sure in air at ambient temperature at the deployment sonde orientation upon retrieval Repeat measurements 3 5 times after the reading has stabilized under con trolled non changing environment in the lab during every calibration or accuracy check event Repeat measurements 3 5 times after the reading has stabilized under con trolled non changing environment in the lab during every calibration or accuracy check event Conduct a one point accuracy check in water upon retrieval before and after cleaning the port the temperature the orientation and the instrument s reading Record the ambient barometric pressure the temperature the orientation and the instrument s reading Results of the 3 5 measurements after stabilization Results of the 3 5 measurements after stabilization Instrument s reading before and after cleaning Check Test to evaluat
26. riodic comparisons of instru ment s readings to DO values as deter mined by the Winkler titration Conduct a two point accuracy check in the field at zero Tip DO1 and 100 air or water saturation at ambient tempera ture during every maintenance event before and after cleaning Conduct a one point accuracy check in the lab at 100 air saturation at room temperature within 24 hours of retrieval before and after cleaning Repeat measurements 3 5 times after the reading has stabilized under con trolled non changing environment in the lab during every calibration or accuracy check event Repeat measurements 3 5 times after the reading has stabilized under con trolled non changing environment in the lab during every calibration or accuracy check event Run fouling comparison test Measure stream water in situ or in bucket before and after cleaning the probe Record Keep everything documented Temperature and atmospheric pressure Tip DO3 Instrument DO reading in mg L and looked up DO saturation in mg L at that temperature and atmo spheric pressure Temperature and atmospheric pressure Tip DO3 Instrument DO reading in mg L and looked up DO saturation in mg L at that temperature and atmo spheric pressure Results of the 3 5 measurements after stabilization Results of the 3 5 measurements after stabilization Pre cleaning inspection and photograph ic records of fouling instrument rea
27. tan dard expressed either in measurement units or as percent of standard s true value whichever is higher i Compute the standard deviation of the 3 5 values and report in measurement units ii Compute the relative percent dif ference RPD which is the difference between repeated field measurements pair or between two extreme values among several repetitions expressed as percentage of pair average iii Compute the relative standard devia tion RSD which is the standard devia tion expressed as a percentage of the average of all repeated values Tip A4 Calculate fouling error bias as the difference between the reading of the un cleaned sensor and the cleaned sensor expressed as a percent of the reading after cleaning Tip A2 Continued on Reverse Continued from Front General All Sensors Data Quality Assurance Actions Documentation Actions Quality Affect Control act to influence the Check Test to evaluate or verify Record Keep everything documented Report Communicate the data quality Aspect outcome indicator Validity Protect sensors probes display units Observe response in changing conditions instrument amp consoles from extreme temperatures Tips A6 A7 is func shocks and solar radiation tional Validity Select the appropriate probe or gain for For Turbidity Check if results are below within the anticipated environmental range of the max value that can be reporte
28. tic pressure so the measure ment results reflect the true depth However they must always be used deployed with a venting cable that leads to a humidity free inner chamber Tip DE1 Vented Depth probes must be connected via a vented cable at all times and have active desiccant in the inner chamber Tip DE2 Depth sensors slopes are calibrated by the manufacturers but it is always necessary to zero the sensor s reading to ambient conditions by adding the depth offset at the ambient barometric pressure and the elevation offset if needed Tip DE3 A Depth measurement Result of a non vented sensor reflects the sum of barometric pressure and hydrostatic pressure head and must be post processed i e corrected for the real barometric pressure at each measurement s time Tip DE4 Continuous Depth measurements must be post processed i e corrected with continuous barometric pressure measurements captured at the same elevation for each logging point in time Tip DE5 Precision can be reported as 1 standard deviation SD or as 2 relative percent difference RPD or as 3 relative standard devia tion RSD a k a coefficient of variations CV depending on the number of repeated measurements and the requirements of the data management system or the Program Tip DE6 To keep vents dry and watertight replace desiccant before expiration date and check lubricate O rings in cable and bulkhead connectors very often
29. tion is recommended only if the sensor will be used in anoxic or low oxygen environments Tip DO6 Precision can be reported as 1 standard deviation SD or as 2 relative percent difference RPD or as 3 relative standard deviation RSD a k a coefficient of variations CV depending on the number of repeated measurements and the requirements of the data management system or the Program 4B Dissolved Oxygen Sensors Optical Tip D04 Data Quality Aspect Accuracy Bias Precision Lack of interfer ence or contamina tion Quality Assurance Actions Affect Control act to influence the outcome Keep the sensor hydrated at all times Conduct a one point calibration in the lab at 100 air saturation at room tem perature before each trip Tip DO5 Keep the sensor hydrated at all times Conduct a one point calibration in the lab at 100 air saturation at room tem perature before each deployment Use consistent procedures under same conditions Use consistent procedures under same conditions Clean probes Clean probes adjust deployment dura tion or maintenance intervals to local conditions Check Test to evaluate or verify Conduct a one point accuracy check at 100 air saturation at room tempera ture within 24 hours of monitoring day s end Run periodic comparisons of instru ment s readings to DO values as deter mined by the Winkler titration Conduct a one point accur
30. ture within 24 hours of retrieval before and after cleaning Repeat measurements 3 5 times after the reading has stabilized under con trolled non changing environment in the lab during every calibration or accuracy check event Repeat measurements 3 5 times after the reading has stabilized under con trolled non changing environment in the lab during every calibration or accuracy check event Conduct a pre cleaning visual inspection and take pictures Tip TU4 Conduct two point accuracy check at zero and at high end of expected range before and after cleaning the probe Check Test to evaluate or verify Record Keep everything documented For each standard record instrument turbidity reading in the technology designated measurement unit Tip TU2 and true value of standard For each standard record instrument turbidity reading in the technology designated measurement unit Tip TU2 and true value of standard Results of the 3 5 measurements after stabilization Results of the 3 5 measurements after stabilization Visual inspection records and picture IDs Tip TU5 Record instrument readings in standard before and after probe fouling removal Report Communicate the data quality indicator Report maximal bias Bias is computed for each standard as the percent differ ence between readings before calibration and readings at the same range after calibration Report maximal b
31. ure ments the true value of NIST Standard and the specified accuracy of the NIST Standard Average of three repeated measure ments the true value of NIST standard and the specified accuracy of the NIST standard Results of the 3 5 measurements after stabilization Results of the 3 5 measurements after stabilization Report Communicate the data quality indicator Report bias Maximal Instrument drift or difference from true value expressed in measurement units Report bias Maximal Instrument drift or difference from true value expressed in measurement units Compute the standard deviation of the 3 5 values and report in measurement units Tip T6 Compute the standard deviation of the 3 5 values and report in measurement units Tip T6 Temperature Sensors Tips amp Comments Tip T1 RTD Resistance Temperature Detectors measure temperature related changes in resistance of a long fine wire wrapped around a ceramic rod Tip T2 The NIST thermometer needs to be re certified every two years Tip T3 Resolution of 0 1 C is mandatory because the thermistor readings are used for temperature compensation in all other sensors on the sonde Tip T4 Always conduct an accuracy check after the instrument fell or was hit by an object Tip T5 Verify current NIST certified or NIST traceable certification of sonde sensor and field thermometer every time Tip T6 Precision can be reported as 1 sta
32. ve clean return to stream bucket measure again After retrieval Conduct two point accuracy check w Standards at zero and at high end of expected range before and after cleaning the probe Record Keep everything documented Record operator name test review date and Test outcome or review summary Reading of standard solutions from the two lots Instrument reading value of standard temperature pressure salinity as rel evant Tips A1 A2 electrode voltage cell constant and other diagnostics as rel evant including their acceptable ranges Instrument reading and value of stan i Record several 3 5 consecutive values after instrument reading s stabili zation ii Results of the repeated field measure ments Document sensor fouling with a digital camera and inspection records before cleaning Tip A5 Record Instru ment readings in situ or bucket or in Standard before and after probe fouling removal Report Communicate the data quality indicator Pass fail procedure specific proficiency tests by individual Report Standard Solution Drift the difference between values measured in solutions of the two lots Report bias Instrument drift i e differ ence from known true value of stan dard expressed either in measurement units or as percent of Standard s true value whichever is higher Tip A3 Report bias Instrument drift i e differ ence from known true value of s
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