Standard Operating Procedure for the Determination of True Color | FOR 251, Study notes of Forestry

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Standard Operating Procedure for the Determination of True Color CCAL 14A.0 Cooperative Chemical Analytical Laboratory Forestry Sciences Laboratory Oregon State University 3200 SW Jefferson Way Corvallis, Oregon Prepared by Kathryn Motter and Cameron Jones April 2006 Color/CCAL 14A.0 April 2006 Page 2 of 9 Standard Operating Procedure for the Determination of True Color CCAL 14A.0 Table of Contents 1.0 Scope and Application ............................................................................... 3 2.0 Summary of Method.................................................................................. 3 3.0 Definitions ................................................................................................... 3 4.0 Interferences ............................................................................................... 3 5.0 Safety ........................................................................................................... 3 6.0 Equipment and Supplies ........................................................................... 4 7.0 Reagents and Standards............................................................................ 4 7.1 Preparation of Standards...................................................................... 4 8.0 Sample Handling and Storage .................................................................. 5 9.0 Quality Control .......................................................................................... 5 10.0 Calibration and Standardization.............................................................. 5 11.0 Procedure.................................................................................................... 6 11.1 Sample Preparation and Analysis ........................................................ 6 11.2 Procedural Notes.................................................................................... 6 12.0 Data Analysis and Calculations ................................................................ 6 13.0 Method Performance ................................................................................. 6 14.0 Pollution Prevention .................................................................................. 7 15.0 Waste Management ................................................................................... 7 16.0 References ................................................................................................... 7 17.0 Tables, Diagrams, Flowcharts, and Validation Data ............................. 8 17.1 Color Analysis Results........................................................................... 8 Color/CCAL 14A.0 April 2006 Page 5 of 9 Dissolve 1.246 g of potassium chloroplatinate (K2PtCl6; equivalent to 500 mg of metallic platinum) and 1.00 g crystallized cobaltous chloride (CoCl2•6H2O; equivalent of approximately 250 mg of metallic cobalt) in approximately 600 mL of DI water with 100 mL concentrated hydrochloric acid in a 1 L volumetric. Dilute to volume with DI water. Stock standard concentration is 500 CU (color units). Prepare fresh annually or as needed. 7.1.2 Potassium chloroplatinate working standards: Volume of Stock Standard (mL) Final Volume (mL) Final Concentration (CU) 0.5 50 5 1.0 50 10 2.0 50 20 2.5 50 25 3.0 50 30 3.5 50 35 4.0 50 40 4.5 50 45 5.0 50 50 6.0 50 60 7.0 50 70 Determine necessary range of standards by visual inspection and comparison of samples with standards. When not in use, cover tubes with parafilm and store in the dark. 8.0 Sample Handling and Storage 8.1 Unfiltered samples are filtered upon receipt through glass fiber filters into clean HDPE bottles and stored at 4°C in the dark. Samples are analyzed within 48 hours to ensure sample integrity. If samples must be held prior to analysis, they are stored frozen at -18ºC. 9.0 Quality Control 9.1 When using previously prepared calibration standards, prepare several new standards and check against old to ensure no degradation. 10.0 Calibration and Standardization 10.1 Balances: calibrated yearly by external vendor. Color/CCAL 14A.0 April 2006 Page 6 of 9 11.0 Procedure 11.1 Sample Preparation and Analysis 11.1.1 Add 50.0 mL of standard or sample to labeled Nessler’s tubes. 11.1.2 Observe the color of each sample in comparison to the standard gradient. Look vertically down, through the tubes towards a white or specular surface placed at such an angle that light is reflected upward through the columns of water. 11.1.3 Record the color value of the nearest matching standard for each sample. Note as true color for filtered samples, and apparent color for unfiltered samples. 11.1.4 If the sample color exceeds 70 units, dilute sample to 50 mL with enough DI water to bring color within standard range. Record volume of sample added. Correct color value for the dilution (see calculations, 12.1). 11.1.5 Analyze samples quickly to minimize bacterial activity which may results in alteration of color. 11.2 Procedural Notes 11.2.1 Samples should be allowed to come to room temperature before analysis. 12.0 Data Analysis and Calculations 12.1 Correction for Dilution Color (CU) = A x 50 mL B where A =color of the diluted sample, B = mL of sample used for dilution 12.2 Report results in whole numbers to nearest 1 for 1 – 50 CU, to nearest 5 for 51 – 100 CU, to nearest 10 for 101 – 250 CU and to the nearest 20 for 251 – 500 CU. 13.0 Method Performance NA Color/CCAL 14A.0 April 2006 Page 7 of 9 14.0 Pollution Prevention 14.1 The chemicals used in this method pose little threat to the environment when properly managed. 14.2 All standards and reagents should be prepared in volumes consistent with laboratory use to minimize the volume of disposable waste. 14.3 For further information on pollution prevention consult Less is better: Laboratory Chemical Management for Waste Reduction, available from the American Chemical Society’s Department of Government Relations and Science Policy, 1155 16th Street NW, Washington D.C. 20036, (202) 872-4477. 15.0 Waste Management 15.1 It is the laboratory’s responsibility to comply with all federal, state and local regulations governing waste management, and to protect the environment by minimizing and controlling all releases from fume hoods and bench operations. Compliance with all sewage discharge permits and regulations is required. 15.2 For further information on waste management, consult “The Waste Management Manual for Laboratory Personnel”, and “Less is Better: Laboratory Chemical Management for Waste Reduction”, both available from the American Chemical Society’s Department of Government Relations and Science Policy, 1155 16th Street NW, Washington DC, 20036. 16.0 References 16.1 Standard Methods For The Examination of Water and Wastewater, Method 2120 – Color, Visual Comparison Method. American Public Health Association. 21st Edition, 2005. 16.2 ASTM. American Society for Testing and Materials. Standard Specifications for Reagent Water. D1193-77 (Reapproved 1983). Annual Book of ASTM Standards, Vol. 11.01. ASTM: Philadelphia, PA, 1991. 16.3 Knight, A. G. 1951. The photometric estimation of color in turbid water. J. Inst. Water Eng. 5:625.