Table of Contents
5940022TOC.fm Page 3
Table of Contents
Hach Company Trademarks ..................................................................................................................2
Section 1 Introduction ........................................................................................................................13
1.1 Abbreviations Used in this Manual ...................................................................................................................13
1.2 Conversions...........................................................................................................................................................14
1.2.1 Chemical Species.........................................................................................................................................14
1.2.2 Hardness.......................................................................................................................................................14
Section 2 Laboratory Practices .........................................................................................................15
2.1 Temperature ..........................................................................................................................................................15
2.2 Mixing ....................................................................................................................................................................15
2.3 Digestion................................................................................................................................................................15
2.3.1 EPA Mild Digestion with Hot Plate for Metals Analysis Only ............................................................16
2.3.2 EPA Vigorous Digestion with Hot Plate for Metals Analysis Only.....................................................16
2.3.3 General Digesdahl Digestion (Not USEPA accepted)............................................................................17
2.4 Distillation .............................................................................................................................................................17
2.5 Filtration.................................................................................................................................................................18
2.5.1 Vacuum Filtration .......................................................................................................................................18
2.5.2 Gravity Filtration ........................................................................................................................................19
2.6 Reagents.................................................................................................................................................................20
2.6.1 Reagent and Standard Stability.................................................................................................................20
2.6.2 Reagent Blank..............................................................................................................................................20
2.7 Sample Dilution ....................................................................................................................................................21
2.7.1 Sample Dilution with Interfering Substances.........................................................................................22
2.8 AccuVac
®
Ampuls................................................................................................................................................22
2.9 PermaChem
®
Pillows ..........................................................................................................................................23
2.10 Sample Cells ........................................................................................................................................................23
2.10.1 Orientation of Sample Cells.....................................................................................................................23
2.10.2 Care of Sample Cells.................................................................................................................................23
2.10.3 Cleaning of Sample Cells .........................................................................................................................24
2.10.4 Matching of Sample Cells ........................................................................................................................24
2.11 Other Apparatus .................................................................................................................................................24
2.11.1 Boiling Aids................................................................................................................................................24
2.12 Achieving Accuracy in Volume Measurement...............................................................................................25
2.12.1 Pipets and Graduated Cylinders ............................................................................................................25
2.12.2 The Pour-Thru Cell ...................................................................................................................................25
Section 3 Chemical Analysis ............................................................................................................27
3.1 Sample Collection, Preservation, and Storage..................................................................................................27
3.1.1 Collecting Water Samples ..........................................................................................................................27
3.1.2 Storage and Preservation ...........................................................................................................................28
3.1.3 Correcting for Volume Additions .............................................................................................................29
3.2 Checking for Accuracy and Precision................................................................................................................31
3.2.1 Standard Solutions......................................................................................................................................31
3.2.2 Standard Additions.....................................................................................................................................32
3.2.3 Explanation of the Standard Additions Decision Tree ..........................................................................32
3.2.4 Adjusting the Standard Curve ..................................................................................................................40
3.3 Interferences ..........................................................................................................................................................41
3.4 Method Performance............................................................................................................................................42
3.4.1 Estimated Detection Limit (EDL) .............................................................................................................42
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