Processing kodak motion picture films, module 3 analytical procedures
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Processing kodak motion picture films, module 3 analytical procedures

Processing kodak motion picture films, module 3 analytical procedures Processing kodak motion picture films, module 3 analytical procedures

motion.kodak.com
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22.07.2013 Views

6 Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03

Potentiometric Determination of Silver in Fixing Baths 1208E Process ECN-2 ECP-2D VNF-1/LC RVNP Formulas — — F-36 F-38 INTRODUCTION The sample is made alkaline to prevent the decomposition of sodium thiosulfate, which occurs in acid solutions. Ethylenedinitrilo tetraacetic acid (EDTA) is added to minimize interference of other metal ions. The EDTA reagent does not prevent interference from zinc ions. Gelatin is added to prevent the coagulation of the silver sulfide that is formed. This prevents the coagulated silver sulfide from occluding the silver ions. The sample containing silver is titrated potentiometrically with standardized sodium sulfide using a silver billet/double junction electrode pair. Changes in the volume of sample and of sodium hydroxide/EDTA reagent affect the silver results. If a small amount of sample is used, the sample volume must be adjusted to about 300 mL with 1.0 M sodium thiosulfate. This method requires handling potentially hazardous chemicals. Consult the Material Safety Data Sheet for each chemical before use. MSDS's are available from your chemical supplier. RELIABILITY Four fixing baths containing 0.100 to 1.00 g/L silver (Ag) were analyzed by two analysts. The 95 percent confidence limits for an individual determination are ± 0.01 g/L silver. SPECIAL APPARATUS pH Meter or Automatic Titrator Reference Electrode, Double Junction, Orion No. 900200 or equivalent (filled with 10 percent potassium nitrate bridge solution in outer chamber) Indicator Electrode, Silver Billet, Beckman No. 39261 or equivalent Note: Use pipets and volumetric glassware meeting the “Class A” definition by the National Institute of Standards and Technology (NIST). REAGENTS Use ACS Reagent Grade reagents unless specified otherwise. 1.0 M Sodium Thiosulfate, Na 2 S 2 O 3 1 N Sodium Hydroxide/Ethylenedinitrilo Tetraacetic Acid (EDTA) Reagent, 1 N NaOH/EDTA 4 g/L Gelatin 0.06 N Sodium Sulfide, Na 2 S (standardized to 4 decimal places) PROCEDURE Sample Treatment 1. Pipet (wipe the pipet before leveling) sample into a 600-mL beaker according to the table below. 2. From a 250-mL graduated cylinder, add to the 600-mL beaker the amount of 1.0 M sodium thiosulfate indicated in the table. Silver Concentration g/L Sample, mL Less than 1 300 * 1.0 M Sodium Thiosulfate, mL 1 to 3 100.0 200 More than 3 50.0 250 * Use a graduated cylinder. 3. Add 100 mL of 1 N NaOH/EDTA reagent from a 50-mL tip-up pipet. 4. Add 10 mL of 4 g/L gelatin from a tip-up pipet. Titration Titrate the sample with standardized 0.06 N sodium sulfide using a silver billet/double junction electrode pair. For instructions, see Method ULM-0003-01, Potentiometric Titrations for Photoprocessing Solutions, (or subsequent revision). Note: Avoid unnecessary exposure of the standardized sodium sulfide to air. The reagent should be standardized each week. Discard all unused reagent remaining in any open bottles at the end of each day (60 mL reagent bottles are suggested for storage of 0.06 N sodium sulfide). Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03 1 0

6 <strong>Processing</strong> KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03

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