Kodak ECN-0002/1 manual Apparatus, Reagents, Procedure

APPARATUS

All volumetric glassware should meet all “Class A” specifications, as defined by American Society for Testing and Materials (ASTM) Standards E 287, E 288, and E 969, unless otherwise stated.

For Potentiometric Titration:

•Metrohm Potentiograph, Model E536 or equivalent titrator

•Metrohm Model 665 Dosimat with a 50-mL burette size (no substitution)

•Electrodes:

Indicator electrode	=	Platinum inlay (i.e., Beckman
		Model 39273 or equivalent)
		Double-junction (i.e., Orion
Reference electrode	=	900200 or equivalent) (10%
		KNO3 outer filling solution)

For Visual Titration:

•Burette, Class A, 50 mL capacity, Teflon stopcock

•Magnetic Stirrer

REAGENTS

Use ACS Reagent Grade reagents unless otherwise specified.

•Potassium Iodate, KIO3 (0.1 N), - standardized to four decimal places

•Acetic Acid, CH3COOH (2.0 N)

•Potassium Iodide, KI (0.6 M)

•Sodium Thiosulfate, Na2S2O3 (0.1 N) - standardized to four decimal places

•Formaldehyde (6%), pH 3.9

•Starch Indicator

•Phenolphthalein Indicator

•Sodium Hydroxide, NaOH (1.0 N)

•Sulfuric Acid, H2SO4 (1.0 N)

•Iodine, I2 (0.1 N) - standardized to four decimal places

•Water, Type I Reagent – This method was developed, and the resulting statistical data were obtained using reagent water equivalent to or purer than Type I Grade, as defined in ASTM Standard D 1193. Other grades of water, e.g., reverse osmosis (RO), demineralized, or distilled water, may give equivalent results, but the effects of water quality on method performance have not been studied.

PROCEDURE

For Potentiometric Titration

A. Hypo Index (HI) or Total Reductants

1.To a 400-mL beaker with a magnetic stir-bar, add 100 mL reagent water.

2.Pipette 40.0 mL (use a 20-mL pipette, twice) of standardized 0.1 N potassium iodate into the 400-mL beaker.

3.While stirring, add 10 mL of 2.0 N acetic acid and

25 mL of 0.6 M potassium iodide (KI) to the 400-mL beaker.

4.With continued stirring, immediately pipette 1.0 mL of sample near the surface of the liquid. Rinse the sides of the beaker with reagent water.

5.Titrate with standardized 0.1 N sodium thiosulfate on an E536 Metrohm Potentiograph or equivalent titrator. If using an E536, titrate the solution from step 4, using the following parameters:

Rate	=	10 min/100% vol
Auto Control	=	OFF
Mode	=	mV/pH
Range	=	500 mV
Burette Size	=	50 mL
Indicator Electrode	= Platinum inlay or platinum
		wire (i.e., Beckman Model
		39273)
Reference Electrode	=	Double-junction reference
		(i.e., Orion Model 90-02)

6.Determine the volume of 0.1 N sodium thiosulfate at the end point using concentric arcs (see Universal Method ULM-0003-01, Potentiometric Titrations for Photoprocessing Solutions, or subsequent revision).

7.Run a blank (do steps 1–6, but omit the addition of the sample in step 4).

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