Titrimetric Determination of EASTMAN Color Developing Agent, CD-3, in Process ECN-2 Developer with Sulfato Cerate

Transcription

1 Titrimetric Determination of EASTMAN Color Developing Agent, CD-3, in Process ECN-2 Developer Sulfato Cerate ECN-0003/1 Process ECN-2 ECP-2B VNF-1/LC RVNP Formulas SD-49 INTRODUCTION This method describes an analytical procedure for measuring EASTMAN Color Developing Agent, CD-3, in Process ECN-2 Developer. CD-3 in the aqueous developer sample is extracted an organic solvent (butyl acetate). An inorganic salt (NaCI) and a surfactant (polystyrene sulfonate) are added to minimize the formation of emulsion layers during the extraction of CD-3. In seasoned samples, an emulsion layer is usually present. If the layer does not transfer to the sulfuric acid, no significant error is introduced. The CD-3 in the solvent layer is then backextracted sulfuric acid. This acid layer can then be titrated sulfato cerate, using either an automatic titrator to record a potentiometric end point or manually titrated using ferroin indicator, to detect the end point visually. The potentiometric titration is recommended over the visual end point titration. However, for those unable to use instrumentation, the manual titrimetric technique, using the visual ferroin indicator, is included. Judging end points a visual color change, especially if the samples are highly seasoned and highly colored, can differ from person to person. The potentiometric method overcomes this problem because the end point is detected potentiometrically and displayed graphically by the titrator. For the potentiometric measurement, a METROHM Potentiograph, Model E536 or equivalent should be used. The potentiometric titration requires a platinum indicator electrode and a double-junction reference electrode. 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. PRECISION AND BIAS Repeatability To obtain the repeatability data, a single skilled analyst performed five (5) replicates on each of the following solutions during methods development (this procedure was performed by both potentiometric and visual end point detection): a. A fresh EASTMAN Color Films, Process ECN-2 developer prepared all components at their respective working tank aim concentrations ( g/l. b. A seasoned EASTMAN Color Films, Process ECN-2 developer analyzed as received at g/l CD-3 (potentiometrically) and g/l CD-3 (visually). c. The same seasoned solution as in number b, above, reanalyzed after making an analytically weighed, standard addition of g/l CD-3 for the potentiometric study and g/l CD-3 for the visual study. (Customer Deviation, 1s c ) Three EASTMAN Color Films, Process ECN-2 developer samples were analyzed by four trained analysts, each using different titration stations, on two different days. Each analyst analyzed each sample by both the potentiometric and the visual end point technique. Duplicate analyses were performed on each sample, on each of the two days. These samples were: a. A fresh tank solution prepared at g/l CD-3. b. An EASTMAN Color Films, Process ECN-2 seasoned tank developer sample analyzed, as received, in the same manner as the fresh developer. c. The same (as in #b, above) EASTMAN Color Films, Process ECN-2 seasoned tank developer sample reanalyzed in the same manner as the fresh developer, after a standard addition of CD-3 was made. The seasoned sample of EASTMAN Color Films, Process ECN-2 developer, analyzed to be g/l CD-3 (potentiometrically) and g/l CD-3 (visually). A standard addition of g/l CD-3 was made to that seasoned sample for the potentiometric and visual calibration study. Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H

2 POTENTIOMETRIC TITRATION STATISTICS Repeatability Deviation, 1s r Repeatability Deviation is an estimate of the variability one trained analyst should be able to obtain under favorable conditions (analyzing a sample, one instrument, in one day). The 95 percent confidence estimate (calculated using the repeatability standard deviation) around a single test will ( g/l, CD-3 (Potentiometrically) Repeatability Deviation, 1S r ± ± ± for fresh samples only. is not determined for seasoned A statistically significant low bias (of 3.4 percent) for CD-2 was found for a Process ECN-2 fresh tank developer sample. However, the bias for was judged not to be practically significant. calculated mean for the seasoned sample a standard 94.9 percent is statistically different from 100 percent. Customer Deviation, 1s c & (not including bias) The customer standard deviation (1s c ) is an estimate of the variability a customer could expect when submitting a sample to any Photoprocessing Quality Services laboratory, where any trained analyst could test the sample using any instrument on any day. The 95 percent confidence estimate (calculated using the customer standard deviation) around a single test result will (4.008 g/l, CD-3 (Potentiometrically) Deviation, 1S c ± ± ± for fresh samples only. is not determined for seasoned A statistically significant low bias (of 4.9 percent) for CD-2 was found for a Process ECN-2 fresh tank developer sample. However, the bias for was judged not to be practically significant. calculated mean for the seasoned sample a standard 94.1 percent is statistically different from 100 percent. 2 Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03

3 VISUAL TITRATION STATISTICS Repeatability Deviation, 1s r and Repeatability Deviation is an estimate of the variability one trained analyst should be able to obtain under favorable conditions (analyzing a sample, one instrument, in one day). The 95 percent (calculated using the repeatability standard deviation) around a single test will (4.008 g/l, CD-3 (Visually) Repeatability Deviation, 1S r ± ± ± for fresh samples only. is not determined for seasoned A statistically significant low bias for CD-2 (of 3.1 percent) was found for a fresh tank Process ECN-2 developer sample. However, the bias for was judged not to be practically significant. calculated mean for the seasoned sample a standard 85.6 percent is statistically different from 100 percent. Customer Deviation, 1s c & (not including bias) The customer standard deviation (1s c ) is an estimate of the variability a customer could expect when submitting a sample to any Photoprocessing Quality Services laboratory, where any trained analyst could test the sample using any instrument on any day. The 95 percent confidence estimate (calculated using the customer standard deviation) around a single test result will (4.008 g/l, CD-3 (Visually) Deviation, 1S c ± ± ± for fresh samples only. is not determined for seasoned A statistically significant low bias for CD-2 (of 4.4 percent) was found for a fresh tank Process ECN-2 developer sample. However, the bias for was judged not to be practically significant. calculated mean for the seasoned sample a standard 93.8 percent is statistically different from 100 percent. Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H

4 APPARATUS All volumetric glassware should meet all Class A specifications, as defined by American Society for Testing and Materials (ASTM) s E 287, E 288, and E 969, unless otherwise stated. Pipette, (50-mL) Separatory funnels, (250-mL) Beakers, (250-mL) Exhaust hood METROHM 536 Titrator or equivalent a DOSIMAT and a 20-mL burette Platinum indicator electrode, BECKMAN, Model or equivalent Double junction reference electrode, ORION Model or equivalent Filling solutions: ORION No (inner chamber) ORION No (outer chamber) Burette, (25-mL) / (visual method only) Magnetic stirrer / (visual method only) REAGENTS Use ACS Reagent Grade reagents unless specified otherwise. Polystyrene Sulfonate, (0.1%) Butyl Acetate Ferroin Indicator Sulfuric Acid, H 2 SO 4, (1.0 N) Sulfato Cerate, (NH 4 ) 2 Ce(NO 3 ) 6, (0.05N) standardized to 4 places past the decimal point Sodium Chloride, NaCl PROCEDURE Extraction of the Developing Agent, CD-3, Butyl Acetate 1. Pipette 50.0 ml (potentiometric titration) or 50.0 ml (visual titration) of sample into a 250-mL separatory funnel (No. 1). 2. Add 5.0 g NaCl to the separatory funnel. 3. Add 2 ml of 0.1% polystyrene sulfonate solution. Stopper the funnel and mix, by gently swirling or shaking, until all the salt completely dissolves. 4. Add 50 ml of butyl acetate. Swirl the funnel for 30 seconds. Stopper the funnel, invert and vent through the stopcock. Shake separatory funnel No. 1, horizontally, for a few seconds; invert and vent the funnel through the stopcock. Continue to shake vigorously for 30 seconds. The funnel should be vented at least 2 times. 5. Allow the layers to separate. Gently swirling the funnel will aid breaking up any emulsion at the aqueous-nonaqueous interface. 6. After separation of the layers occurs, transfer the lower (aqueous) layer, as completely as possible, including any emulsion that fails to separate, into another 250-mL separatory funnel (No. 2). 7. Swirl separatory funnel No. 1. Drain any additional lower (aqueous) layer that separates into separatory funnel No. 2. Save the top (butyl acetate) layer in separatory funnel No Add 50 ml of butyl acetate to separatory funnel No. 2. Swirl the funnel for 30 seconds. Stopper the funnel; invert and vent through the stopcock. Shake the funnel horizontally for a few seconds; invert and vent through the stopcock. Continue to shake the funnel vigorously for 30 seconds, venting at least 2 times. 9. After the layers separate, discard the lower (aqueous) layer as completely as possible. Swirl the funnel and discard any additional aqueous layer that separates, taking care not to lose any of the butyl acetate layer. Discard any emulsion layer that fails to separate. Note: al separation time may be needed for highly seasoned samples. 10. Transfer the contents of separatory funnel No. 2 (butyl acetate layer) into funnel No. 1 (which contains the first butyl acetate layer). 4 Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03

5 Back-Extraction of the Developing Agent 1. Add 100 ml of 1.0 N sulfuric acid to separatory funnel No. 2 and swirl, rinsing the inside walls of the funnel. Save the funnel contents for step Gently swirl separatory funnel No. 1 and discard, as completely as possible, any lower (aqueous) layer that separates, taking care not to lose any of the butyl acetate layer. 3. Transfer the contents of separatory funnel No. 2 into funnel No Swirl the funnel for 30 seconds. Stopper the funnel; invert and vent through the stopcock. Shake the separatory funnel horizontally for a few seconds; invert and vent through the stopcock. Continue to shake vigorously for 30 seconds, venting 2 times. 5. Allow enough time for complete separation of the phases. Note: It may take longer for complete separation of the phases in highly seasoned samples. 6. Transfer the lower (acid) layer from separatory funnel No. 1 to a 250-mL beaker out losing any of the top layer. 7. Swirl separatory funnel No. 1 and transfer any additional lower (acid) layer that separates, as completely as possible, into the beaker. Titration of the Developing Agent Sulfato Cerate Note: The end-point of the titration step can be determined either potentiometrically (Step 1 below) or visually (Step 2 below). 1. Potentiometric Titration a. Add 5 drops of ferroin indicator and a magnetic stir bar to the 250-mL beaker (from steps 6 & 7 of the Back-Extraction of the Developing Agent procedure). Note: Do not omit the ferroin, it aids the definition of the end point. b. Set the following parameters, if using a METROHM 536 titrator: Titration mode Horizontal chart span Autocontrol Maximum titration speed Vertical chart span Automatic titration stop (U%) Indicator electrode mv/ph 750 mv OFF 15 min/100% volume 400 mm/100% volume OFF Platinum, BECKMAN, Model or equivalent Reference electrode Double-junction ORION, Model or equivalent c. Place the 250-mL beaker on the METROHM titrator stand and add a magnetic stir bar. Place the electrodes in the beaker. (NOTE: The titrant delivery tip should be placed so that the titrant flows past the reference electrode before the platinum electrode.) Set the stirrer speed to stir rapidly out splashing or creating a vortex. Titrate the solution standardized 0.05 N sulfato cerate through the inflection. d. Determine the end point using concentric arcs. (Refer to Universal Method ULM , Potentiometric Titrations for Photoprocessing Solutions, or any subsequent revisions.) Record the end point as ml A. e. Add 100 ml of 1.0 N sulfuric acid to a second 250-mL beaker containing a magnetic stir bar. Add 5 drops of ferroin indicator. f. Place the second beaker on the METROHM titrator stand and titrate through the inflection point standardized 0.05 N sulfate cerate. Record any measurable end point as ml B. (This is the blank. This determination needs to be performed only once, if a series of analyses will be performed.) Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H

6 2. Visual Titration: a. Place the 250-mL beaker (from steps 6 & 7 of the Back-Extraction of the Developing Agent procedure) on a magnetic stirrer after adding a magnetic stir bar. Add 5 drops of ferroin indicator. Turn the magnetic stirrer on and adjust the setting so that the solution stirs vigorously but out creating a vortex or splashing. b. Using a 25-mL burette, titrate the solution standardized 0.05 N sulfato cerate to the first green color that persists for 15 seconds. Record the end point as ml A. c. Add 100 ml of 1.0 N sulfuric acid to a second 250-mL beaker containing a magnetic stir bar. Add 5 drops of ferroin indicator and place the beaker on a magnetic stirrer. Turn the magnetic stirrer on and adjust the setting so that the solution stirs vigorously out creating a vortex or splashing. d. Titrate the solution to the first light blue color that persists for 30 seconds. Record the end point as ml B. (This is the blank. This determination needs to be determined only once, if a series of analyses will be performed.) Calculations ml A - ml B = ml 0.05 N sulfato cerate, consumed by the sample g/l CD-3 = (ml sulfate cerate)(n sulfate cerate)(eq. wt. (1000) (ml sample)(1000) g/l CD-3 = (ml sulfato cerate)(n sulfato cerate)(218.26)(1000) (50 ml)(1000) Where: eq. wt. CD-3 (218.26) = equivalent weight of CD-3 sesquisulfate monohydrate 6 Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03