Hach DR 5000 user manual Standard Addition monitoring/checking results, Method

Page 82

Advanced Operations

6.3 Standard Addition – monitoring/checking results

The accuracy of measured values (their correspondence with the actual concentration of the analyte in the sample) and their precision (correspondence of the measurement results obtained from several samples containing the same concentration of the test analyte) can be determined or improved using the standard addition method.

This method (also referred to as spiking) serves to identify sample-specific interference factors, e.g. substances in the sample that falsify the analysis (sample matrix effect), a defective measuring instrument or contaminated reagents.

Method:

A defined amount (concentration) of a standard solution of the test substance is added to the sample. The detection rate should be close to 100%.

Measured value after a standard addition

Detection rate = ------------------------------------------------------------------------------------------------------------

Expected value after a standard addition

Detection rate

Conclusion

 

 

 

100%

Probability that the measurement results are correct

is high.

 

 

 

 

 

 

Assumption: The analysis was falsified by

 

substances in the sample (sample matrix effect)

< 100%

Test to determine whether a sample matrix effect

is present:

 

 

 

 

Use distilled water instead of the sample. Add

 

standard solution as described in the procedure.

 

 

 

 

Detection rate

Conclusion

 

 

 

 

 

Ions in the sample are

 

100%

interfering with the

 

analysis, causing false

 

 

 

 

results to be obtained.

 

 

 

 

 

No interfering ions -

 

≠ 100%

consider other

 

 

interference factors.

Measures to identify other interference factors:

Checklist:

1.Check if the procedure is completed correctly:

a.Are the reagents added in the correct order?

b.Is enough time allowed for color development?

c.Is the correct glassware in use?

d.Is the glassware clean?

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Contents January 2008, Edition Page Table of Contents Table of Contents 101 Table of Contents Section Specifications Specifications General Information Safety informationPrecautionary labels Use of hazard informationSource Lamp Safety Chemical and Biological SafetyGeneral Information Class 1 Laser Overview of product General InformationGeneral Information Unpack the instrument Section InstallationOperating environment Installation ConnectionCell compartment 1 100 mm adapter optional Multi Cell Holder Top and BottomInstallation Installation Multi Cell Holder Installation Multi Cell HolderBeam path Beam pathStart Up Power the instrument on and offChanging the language setting Language selectionStart Up Tips for the use of the touch screen Standard OperationsOverview Use of the alphanumeric keypadStandard Operations Main Menu Main Menu optionsStandard Operations Instrument Setup modeOperator ID Standard Operations Sample ID Date and time Display and sound preferencesLamp Control VIS-Lamp and UV-LampEffect caused by the lamp settings on the Measuring Mode Standard Operations Standard Operations PC and printer Printer setupUSB connector KeyboardPrinter Setup Print data Hach Data TransPassword Password deactivation Standard Operations Auto/manual data storage Store, recall, send and delete dataData Log Recall stored data from the data logSend data from the data log To send measurement data to a PCDelete stored data from the data log Recall stored data from wavelength scan or time course Data storage from wavelength scan or time courseSelect Wavelength Scan or Time Course to recall data Send data from wavelength scan or time course Option Press Wavelength Scan or Time Course and then Delete stored data from wavelength scan or time course Stored program options Stored ProgramsSelect a saved test/method enter user-specific basic data Stored programs optionsStandard Adjust Timer iconReading Mode Options Description Store Off/OnStandard Operations Use of program timers Set the reading modeTake single wavelength measurements continuous readings Set the dilution factorTake single wavelength measurements single reading Press OptionsMore…Dilution FactorRun a standard adjust Set the chemical form Change of the default setting of the chemical formPress Save as Default Press OptionsMoreChemical FormMeasurement/analysis of a reagent blank Standard Operations Run a reagent blankPress OptionsMoreReagent Blank Standard Operations Analysis of samples Add stored programs to the favorite programs listBarcode Programs Cell compartment #1Select the measuring range Changing the standard settingStandard Operations Complete a barcode 13 mm test/vial Select the chemical evaluation formBasic test-specific and sample-specific data settings Barcode program optionsOptions Description Send Data icon Sample blankEdit Program update options Update/edit barcode testsManual update of a barcode test Enter the NameEnter the Version Enter the Measurement ProcessTimer 1, Timer 2, Timer 3 and Timer Option 2 Manual check/revision of test data Update an existing barcode testOption 1 Manual update of test data Press OptionsMoreEditUpgrade of the instrument software Program a new testPress OK to return to the System Checks menu Standard Operations User Programs Advanced OperationsProgram a user method Program Name Advanced OperationsProgram Number Program TypeUnits Single wavelength settingsConcentration resolution number of decimal places Wavelength single wavelength program typeChemical form Multi wavelength settingsAbsorbance formula multi-wavelength program type Wavelength λx List of available absorbance formulasConcentration Factor Kx Calibration settings Calibration settings for single and multi wavelength modeCalibration by entering calibration values Advanced Operations Advanced Operations Advanced Operations Additional user-defined parameters and functions Store a user programUpper and lower limits of the measuring range Timer 1 / Timer 2 / Timer 3 / Timer Chemical form 2 / chemical form 3 / chemical formMeasurement process Advanced Operations Free programming program typeDefinitions of the program points Content and definition of the keys Key / Zeroing Enter a new element of a measuring sequenceProcess Timer key Key / ReadingInsert an element of a measuring sequence Enter the calibration formula evaluation formulaDelete an element of a measuring sequence Enter calibration formula C1Screen Key Description Edit formula key descriptionsNew Number Enter the next calibration formula C2 or Cn C2 OnSave a free programming user program Enter variablesSelect Conc. key Advanced Operations Select a user program 4 Add, edit and delete user programs from the favorites listEdit Add to FavoritesDelete Recall a favorite program Favorite ProgramsDelete a favorite program Standard Addition monitoring/checking results Measures to identify other interference factors ChecklistMethod Check the standard solution Peak volume Standard additionSample volume Complete a standard additionPeak volume/sample volume methods Press OptionsMoreStandard AdditionDescription of the table of readings Advanced Operations Single wavelength setup options Set up single wavelength modeProgram Concentration factor Concentration resolutionOptions Description Take single wavelength measurements single reading Reading modeTake single wavelength measurements continuous readings Set the reading mode at different wavelengths Multi-wavelength setup optionsAbsorbance formula Press Absorbance Formula Concentration factor For data storage, see .3.1.1 on Set up the wavelength scan Wavelength scan setup optionsOption Description Setting wavelengthScale & Units Select view displaying table Cursor modeIntegral Wavelength scan reading Scale & units Press Scale & UnitsNavigating the wavelength scan Advanced Operations Work with reference scans Highlight Reference100 Time course of absorbance/transmittance Time course setup parametersTime course setup options 101Scale & units Time course scan readingTime & interval 102Analysis of time course data 103Navigating the time scan Navigation of a time scan or a time scan analysis104 Instrument information System checks105 Optical checks Advanced Operations Upgrade of the instrument software106 Wavelength check 107Noise check 108109 Stray light check 110Absorbance check 111Drift check 112Verification kit Press Nominal Values 113Press Verification 114Lamp history Output checks115 Service time Advanced Operations Factory service116 Instrument Backup 117Restore backup data 118119 120 Spectrophotometer MaintenanceCleaning requirements DisplayTungsten lamp replacement Lamp replacementMaintenance 122Deuterium lamp UV replacement 123Fuse replacement 124Filter pad replacement Filter pad maintenance125 Base of DR 5000 with filter grid 126Section Troubleshooting 127Troubleshooting 128129 Section Replacement PartsDescription Cat.-No Replacement Parts 130Contact Information 131Contact Information 132Limitation of Remedies Limited WarrantyLimitations 133Limited Warranty 134Index 135136
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