1、American National Standardfor Photography (Processing) -Photographic Processing Solutions -pH Calibration and MeasurementANSI/I3A IT4.36-2003ANSI/I3AIT4.36-2003ANSI/I3A IT4.36-2003Revision and redesignation ofANSI/NAPM IT4.36-1995American National Standardfor Photography (Processing) -Photographic P
2、rocessing Solutions -pH Calibration and MeasurementSecretariatInternational Imaging Industry Association, Inc. (I3A)Approved December 23, 2003American National Standards Institute, Inc.Approval of an American National Standard requires review by ANSI that therequirements for due process, consensus,
3、and other criteria for approval havebeen met by the standards developer.Consensus is established when, in the judgement of the ANSI Board ofStandards Review, substantial agreement has been reached by directly andmaterially affected interests. Substantial agreement means much more thana simple majori
4、ty, but not necessarily unanimity. Consensus requires that allviews and objections be considered, and that a concerted effort be madetowards their resolution.The use of American National Standards is completely voluntary; theirexistence does not in any respect preclude anyone, whether he has approve
5、dthe standards or not, from manufacturing, marketing, purchasing, or usingproducts, processes, or procedures not conforming to the standards.The American National Standards Institute does not develop standards andwill in no circumstances give an interpretation of any American NationalStandard. Moreo
6、ver, no person shall have the right or authority to issue aninterpretation of an American National Standard in the name of the AmericanNational Standards Institute. Requests for interpretations should beaddressed to the secretariat or sponsor whose name appears on the titlepage of this standard.CAUT
7、ION NOTICE: This American National Standard may be revised orwithdrawn at any time. The procedures of the American National StandardsInstitute require that action be taken periodically to reaffirm, revise, orwithdraw this standard. Purchasers of American National Standards mayreceive current informa
8、tion on all standards by calling or writing the AmericanNational Standards Institute.American National StandardPublished byAmerican National Standards Institute, Inc.25 West 43rd Street, New York, NY 10036Copyright 2004 by American National Standards Institute, Inc.All rights reserved.No part of thi
9、s publication may be reproduced in anyform, in an electronic retrieval system or otherwise,without prior written permission of the publisher.Printed in the United States of AmericaiContentsPageForeword iiIntroduction . iii1 Scope 12 Normative references 13 Terms and definitions 14 Principle 15 Relia
10、bility. 26 Materials and reagents 37 Apparatus 58 Sample preparation. 69 Procedures 610 Expression of results. 911 Test report. 9AnnexesA Electrode care 10B Standardization of calibration buffer solutions 12C Approved package buffers 15D Bibliography 17iiForeword (This foreword is not part of Americ
11、an National Standard ANSI/I3A IT4.36-2003.)American National Standard ANSI/I3A IT4.36 was prepared by I3A Technical Com-mittee IT4, Photographic Processing. This second edition cancels and replaces thefirst edition (ANSI/NAPM IT4.36-1995) of which it constitutes a technical revision.This standard co
12、ntains four annexes. Annexes A and B are normative and are an in-tegral part of this standard. Annexes C and D are for information only and are notconsidered part of this standard.Suggestions for improvements of this standard will be welcome. They should be sentto the International Imaging Industry
13、Association, Inc. (I3A), 550 Mamaroneck Ave-nue, Suite 310, Harrison, NY 10528-1612, e-mail: i3astdsi3a.org.This standard was processed and approved for submittal to ANSI by I3A TechnicalCommittee on Photographic Processing, IT4. Committee approval of the standarddoes not necessarily imply that all
14、committee members voted for its approval. At thetime it approved this standard, the IT4 Committee had the following members:Joseph M. Rao, ChairmanOrganization Represented Name of RepresentativeInternational Imaging Industry Association, Inc. (I3A) Jan CarlockLinda CrosbyKunihiro FujiwaraAnthony Jar
15、kowskiRonald A. KleinGeneral Chemical Corporation. Mark DulikPhotographic Society of America . Grant HaistPhoto Marketing Association International . Herb SteinIndividual ExpertsJohn GignacPeter KrauseJoseph M. RaoiiiIntroductionConsistent, high-quality photographic processing depends not only upon
16、the use ofreasonably pure chemicals, but also the proper solution of these chemicals duringformulation and the close control of those solutions during the processing of photo-graphic materials.The reliable determination of the pH of the photographic processing solution is nec-essary in order to main
17、tain the quality of the product sold by the manufacturer and tomaintain the activity of the processing solution during its working lifetime.AMERICAN NATIONAL STANDARD ANSI/I3A IT4.36-2003American National Standard for Photography (Processing) Photographic Processing Solutions pH Calibration and Meas
18、urement 1 1 Scope This standard specifies a method for the measurement of pH over the range of 2 to 14 in working strength and concentrates of photographic processing solutions. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provis
19、ions of this American National Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this American National Standard are encouraged to investigate the possibility of applying the most recent editions of the
20、standards listed below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 6353-1:1982, Reagents for chemical analysis Part 1: General test methods ISO 6353-2:1983, Reagents for chemical analysis Part 2: Specifications First seriesISO 6353-3:1987, Reagents for
21、chemical analysis Part 3: Specifications Second seriesISO 10349-1:1992, Photography Photographic-grade chemicals Test methods Part 1: General3 Terms and definitions For the purposes of this standard, the following terms and definitions apply. 3.1 calibrating buffers: Buffers used to prepare the pH m
22、eter for measurement of samples. 3.2 reference buffers: Buffers used to standardize the calibrating buffers. NOTE These buffers are prepared by the National Institute of Standards and Technology (NIST) procedures with NIST materials. Values for NIST buffers will change only if a new lot of standard
23、reference material is used. 3.3 standardization: Process through which a pH value is assigned to a calibrating buffer using reference buffers. 4 Principle A two-point calibration system is used for measuring pH, utilizing either low pH-range or high pH-range buffer pairs with nominal values of pH 4
24、and pH 7 or pH 7 and pH 10, respectively. These ANSI/I3A IT4.36-2003 2 calibrating buffer solutions are assigned pH values to three decimal places by measured comparison with reference buffers made from NIST Standard Reference Materials (SRMs).1)Control buffers of pH values 3.63 and 11.43 at 25oC ar
25、e used as measurement controls to verify system accuracy. All sample solutions and buffers shall be equilibrated at 25oC before pH measurement and stirred during calibration and measurement. 5 Reliability 5.1 Precision pH measurements were made on seven processing solutions (two acidic and five basi
26、c) by three analysts over a period of two days using three different pH meters, six different pH electrodes, and three different reference electrodes. Results of this study are as follows: The standard deviation increased at higher pH values; The pH response of glass electrodes is imperfect at the e
27、xtreme ends of the pH scale. Therefore, the pH range in which the measurement is performed will contribute to measurement variability; For working-strength processing solutions with pH values below 10, the pooled standard deviation (1 sigma) is +0.005 pH units with a 95% confidence estimate (2 sigma
28、) of +0.010 pH units; For working strength processing solutions with pH values above 10, the pooled standard deviation (1 sigma) is +0.011 pH units with a 95% confidence estimate (2 sigma) of +0.023 pH units. 5.2 Bias This test method is based on chemical theory and the measurement of reference buff
29、er solutions, and this method is expected to provide an accurate measure of the pH of photoprocessing solutions. 5.3 Sources of error 5.3.1 In order to reduce aerial oxidation and prevent dilution, evaporation and contamination of solutions, it is recommended that sample solutions and buffers be cov
30、ered or capped during temperature equilibration to 25oC. 5.3.2 The use of either reference or calibrating buffers that are contaminated or past their expiration date can prevent calibration of the pH meter within the specified buffer tolerances. 5.3.3 A change in temperature of 1oC produces a change
31、 of 0.015 pH units to 0.020 pH units in carbonate-buffered developers of pH 10. For photoprocessing solutions of higher pH that are not as well buffered, this variation with temperature can be 0.030 pH units per oC or greater. Because of this effect, careful control of temperature is essential for p
32、recise and accurate measurement of pH. 1)Available from the National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899; Telephone: 301/975-6776. ANSI/I3A IT4.36-2003 3Temperature control requirements are described in 6.1.4, 9.1.2, 9.1.3, 9.1.4, and 9.2. 5.3.4 For the greatest prec
33、ision, stirring of solutions is recommended both during meter calibration and sample pH measurement. With stirring, the 95% confidence limits for measurements of the pH 4 phthalate reference buffer by a single analyst were +0.007 pH units; without stirring, the 95% confidence limits were +0.023 pH u
34、nits. Ten measurements were made with and without stirring with recalibration of the meter between measurements. 5.3.5 Clogging of reference electrode junctions occurs quite readily in photoprocessing solutions due to the high ionic strengths and complicated matrices present, but these reference ele
35、ctrodes can be tested in several ways for proper performance. A procedure to check and clear a clogged junction is given in annex A, as well as a method to check for liquid-junction problems. New reference electrodes with ceramic frit or plug-type junctions perform well, but should be checked regula
36、rly for electrolyte flow. Check the junction for flow more often if frequent measurements are made. Sleeve-type junction reference electrodes gave the best results for accuracy and precision. However, due to the high flow rate of the filling solution, close attention is required to ensure that the e
37、lectrode has adequate filling solution, and that the electrolyte is not allowed to drain completely into the sample to be measured. This is necessary both for proper performance of the electrode and to avoid sample contamination. 5.3.6 During pH meter calibration, the slope may be determined by adju
38、sting a manual slope control or reading the slope value calculated by the meter. Historically, 95% of the Nernstian electrode response has been used as the cut-off point for continued use of electrodes for pH measurements. The present slope criterion is a range of 98.0% to 102.0% of the Nernstian re
39、sponse. 6 Materials and reagents 6.1 General 6.1.1 Handling and labeling Reagents shall be handled in conformity with health and safety precautions as shown on containers, or as given in other sources of such information. Proper labeling of prepared reagents includes chemical name, date of preparati
40、on, expiration date, restandardization date, name of preparer, and adequate health and safety precautions. The discharge of reagents shall conform to applicable environmental regulations. 6.1.2 Purity Reagents used in the test procedures shall be certified reagent-grade chemicals and shall meet appr
41、opriate standards or be chemicals of a purity acceptable for the analysis. For details, see ISO 6353-1, ISO 6353-2, and ISO 6353-3. ANSI/I3A IT4.36-2003 4 6.1.3 Water Whenever water is specified without other qualifiers in the test procedures, only distilled water or water of equal purity shall be u
42、sed. 6.1.4 Temperature equilibration All samples and buffer solutions shall be equilibrated to the measurement temperature, 25oC. Water-baths should be used to provide circulation around the sample containers, and to maintain the temperature of the samples and buffers to within +0.25oC. To eliminate
43、 reading error, use a recently calibrated digital thermometer for water temperature measurements. Calibrate any thermometer used for verifying water-bath temperature against a NIST or another standard thermometer on a yearly basis or according to standard laboratory operating procedures. Use circula
44、ting rather than static water-baths to provide faster equilibration times and more uniform temperatures. 6.1.5 Stirring Air or water-driven magnetic stirrers that can be immersed in the water-baths shall be used. In tests of this type of stirrer, the water-bath temperature was not affected by the wa
45、ter circulating in the tubing to and from the stirrer. In a 28-liter circulating bath, no change in bath temperature occurred. For viscous samples or when a smaller stirrer (bath-immersible dimensions) is necessary, a submersible magnetic stirrer2)with an isolated power supply is satisfactory. A pad
46、dle or propeller-type stirrer can be used to stir the solutions directly, if adequate rinsing between samples is provided. Moderate stirring shall be provided in order to present a uniform sample to the electrode pair while avoiding excessive oxidation during measurement. Avoid vigorous stirring tha
47、t draws a large amount of air into the solution. 6.2 Reagents Buffers and storage solutions required for the pH method include the following: pH 4.01 phthalate reference buffer; pH 6.86 phosphate reference buffer; pH 9.18 borate reference buffer; pH 4 phthalate calibration buffer; pH 7 phosphate cal
48、ibration buffer; pH 10 carbonate calibration buffer; pH 3.63 tartrate low pH control buffer; pH 11.43 phosphate high pH control buffer; 2)A Troemer model 700 is an example of a suitable product available commercially. This information is given for the convenience of users of this standard and does n
49、ot constitute an endorsement by I3A or ANSI of this product. ANSI/I3A IT4.36-2003 5 Reference electrode filling and long-term storage solution (3.5 mol/l potassium chloride); Reference electrode temporary storage solution (0.1 mol/l potassium chloride in pH 7 phosphate calibration buffer). All the above buffer pH values are nominal and all values used in pH measurements are based on current NIST chemical lot numbers, or are assigned after meter standardization with reference buffers. All these buffers and storage solutions are commercial
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