ASTM D5386-16

Standard Test Method for Color of Liquids Using Tristimulus Colorimetry

SIGNIFICANCE AND USE
4.1 The primary objective of the visual method of Pt-Co color measurement, as defined in Test Method D8005, is to rate specific materials for yellowness. This yellowness is frequently the result of the undesirable tendency of liquid hydrocarbons to absorb blue light due to contamination in processing, storage or shipping.  
4.2 Clear liquids can be rated for light absorbing yellowish or brownish contaminants using scales that simulate the long-established visual-comparison method.
SCOPE
1.1 This test method covers an instrumental method for the CIE (Commission International de l’Eclairage) tristimulus measurement of the color of near-clear liquid samples. The transmission measurement values are converted to the color scale in the platinum-cobalt (Pt-Co) system.  
1.2 This test method has been found applicable to the color measurement of clear, liquid samples, free of haze, with nominal Pt-Co color values in the 0 to 100 range. It is applicable to non-fluorescent liquids with light absorption characteristics similar to those of the Pt-Co color standard solutions.  
1.3 The tristimulus colorimetry may be calculated from spectral measurements or be obtained directly from a colorimeter. Practice E1455 provides some guidance on colorimeters, while Test Methods D1686 and D2108 deal with the visual and instrumental measurement of near-clear liquids.  
1.4 In determining the conformance of the test results using this method to applicable specifications, results shall be rounded in accordance with the rounding off methods of Practice E29.  
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 8.

General Information

• Status: Published
• Publication Date: 30-Nov-2016
• ICS: 71.080.01 - Organic chemicals in general
• Technical Committee: D16 - Aromatic, Industrial, Specialty and Related Chemicals
• Drafting Committee: D16.04 - Instrumental Analysis

Relations

• Refers: ASTM D2108-10(2020) - Standard Test Method for Color of Halogenated Organic Solvents and Their Admixtures (Platinum-Cobalt Scale)
• Effective Date: 01-Jan-2020
• Refers: ASTM E308-17 - Standard Practice for Computing the Colors of Objects by Using the CIE System
• Effective Date: 01-May-2017
• Refers: ASTM D6809-02(2016) - Standard Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials
• Effective Date: 01-Nov-2016
• Refers: ASTM E1455-16 - Standard Practice for Obtaining Colorimetric Data from a Visual Display Unit Using Tristimulus Colorimeters
• Effective Date: 01-Jul-2016
• Refers: ASTM D8005-15 - Standard Test Method for Color of Clear Liquids (Platinum-Cobalt Scale)
• Effective Date: 01-Jun-2015
• Refers: ASTM D2108-10(2015) - Standard Test Method for Color of Halogenated Organic Solvents and Their Admixtures (Platinum-Cobalt Scale)
• Effective Date: 01-Jun-2015
• Refers: ASTM E308-15 - Standard Practice for Computing the Colors of Objects by Using the CIE System
• Effective Date: 01-Apr-2015
• Refers: ASTM E313-15 - Standard Practice for Calculating Yellowness and Whiteness Indices from Instrumentally Measured Color Coordinates
• Effective Date: 01-Jan-2015
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E179-12 - Standard Guide for Selection of Geometric Conditions for Measurement of Reflection and Transmission Properties of Materials
• Effective Date: 01-Jul-2012
• Refers: ASTM E308-12 - Standard Practice for Computing the Colors of Objects by Using the CIE System
• Effective Date: 01-Jul-2012
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM D3437-11 - Standard Practice for Sampling and Handling Liquid Cyclic Products
• Effective Date: 01-Jan-2011
• Refers: ASTM E313-10 - Standard Practice for Calculating Yellowness and Whiteness Indices from Instrumentally Measured Color Coordinates
• Effective Date: 01-Jul-2010
• Refers: ASTM D3437-10 - Standard Practice for Sampling and Handling Liquid Cyclic Products
• Effective Date: 01-Jun-2010

Overview

ASTM D5386-16 is the Standard Test Method for Color of Liquids Using Tristimulus Colorimetry, developed by ASTM International. This standard provides an instrumental method for measuring the color of near-clear liquid samples using tristimulus colorimetry, referencing the CIE (Commission Internationale de l’Eclairage) system. The measurement values are converted to the platinum-cobalt (Pt-Co) color scale, commonly used to assess the presence of yellowish or brownish contaminants in clear liquids, such as hydrocarbons. This standard is crucial for determining product purity and the potential presence of processing contamination in various industries.

Key Topics

• Tristimulus Colorimetry:
  The standard outlines the use of CIE tristimulus values (X, Y, Z) to evaluate color, enabling results that simulate human visual perception and providing objective, reproducible color ratings.

• Platinum-Cobalt (Pt-Co) Scale:
  The Pt-Co scale is a well-established method for rating the color of clear liquids between 0 and 100, particularly for identifying yellow tints due to contaminant absorption of blue light.

• Instrumental vs. Visual Methods:
  ASTM D5386 offers an instrumental alternative to visual comparison methods, such as those described in ASTM D8005 and D1209, improving measurement accuracy and reducing operator variability.

• Sample and Apparatus Requirements:

  • The method applies to non-fluorescent, haze-free clear liquids.
  • Samples are analyzed in clear, colorless cells of defined path lengths.
  • Instrument calibration is based on distilled water, with routine verification using Pt-Co color standards.

• Quality and Precision Controls:
  Procedures for instrument calibration, quality control sampling, and precision and reproducibility parameters are specified to ensure reliability in results.

• Scope Limitations:

  • Applicable for Pt-Co color values within 0-100.
  • Results must be given in SI units.
  • Does not address all safety or regulatory considerations-users must establish appropriate practices.

Applications

ASTM D5386-16 is widely utilized in quality control, product specification, and regulatory compliance across sectors where liquid purity and color are critical:

• Petrochemical and Hydrocarbon Processing:
  Detects yellowish or brownish tint caused by contamination during processing, storage, or shipping, providing insight into product quality and potential impurities.

• Pharmaceuticals, Solvents, and Fine Chemicals:
  Ensures compliance with color specifications, indicating purity of non-fluorescent, near-clear liquid chemicals.

• Environmental Monitoring:
  Assesses water and effluent samples for traces of organic contaminants that can impact color.

• Industrial Quality Assurance Laboratories:
  Employs objective, traceable methods for routine color analysis, enhancing consistency across production batches.

• Regulatory Reporting:
  Supports conformance to international, regional, and customer-specific color standards for clear liquids.

Related Standards

Several other ASTM standards and references complement or are referenced by ASTM D5386-16:

• ASTM D8005: Visual test method for color of clear liquids (Pt-Co scale).
• ASTM D1209: Test method for Pt-Co color measurement using visual comparison.
• ASTM D1686: Test method for color of solid aromatic hydrocarbons in molten state (Pt-Co scale).
• ASTM D2108: Instrumental measurement for color of halogenated organic solvents (Pt-Co scale).
• ASTM E29: Practice for rounding off in test data.
• ASTM E308: Practice for computing colors using the CIE system.
• ASTM E313: Calculation of yellowness and whiteness indices from measured color coordinates.
• ASTM E1455: Guidance on using tristimulus colorimeters.
• ASTM D3437, D6809: Procedures for liquid sample handling and laboratory quality control.

By following ASTM D5386-16, laboratories can achieve reliable, standardized results in liquid color measurement, supporting quality assurance and specification compliance for critical applications.

Keywords: tristimulus colorimetry, Pt-Co, platinum-cobalt scale, instrumental color measurement, hydrocarbons, clear liquids, ASTM D5386-16.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D5386 − 16
Standard Test Method for
Color of Liquids Using Tristimulus Colorimetry
This standard is issued under the fixed designation D5386; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers an instrumental method for the
D1193 Specification for Reagent Water
CIE (Commission International de l’Eclairage) tristimulus
D1686 Test Method for Color of Solid Aromatic Hydrocar-
measurement of the color of near-clear liquid samples. The
bons and Related Materials in the Molten State (Platinum-
transmission measurement values are converted to the color
Cobalt Scale)
scale in the platinum-cobalt (Pt-Co) system.
D2108 Test Method for Color of Halogenated Organic
1.2 This test method has been found applicable to the color
Solvents and Their Admixtures (Platinum-Cobalt Scale)
measurement of clear, liquid samples, free of haze, with
D3437 Practice for Sampling and Handling Liquid Cyclic
nominal Pt-Co color values in the 0 to 100 range. It is Products
applicable to non-fluorescent liquids with light absorption D6809 Guide for Quality Control and Quality Assurance
Procedures for Aromatic Hydrocarbons and Related Ma-
characteristics similar to those of the Pt-Co color standard
terials
solutions.
D8005 Test Method for Color of Clear Liquids (Platinum-
1.3 The tristimulus colorimetry may be calculated from
Cobalt Scale)
spectral measurements or be obtained directly from a colorim-
E29 Practice for Using Significant Digits in Test Data to
eter. Practice E1455 provides some guidance on colorimeters,
Determine Conformance with Specifications
whileTest Methods D1686 and D2108 deal with the visual and
E179 Guide for Selection of Geometric Conditions for
instrumental measurement of near-clear liquids.
Measurement of Reflection and Transmission Properties
of Materials
1.4 In determining the conformance of the test results using
E308 PracticeforComputingtheColorsofObjectsbyUsing
this method to applicable specifications, results shall be
the CIE System
rounded in accordance with the rounding off methods of
E313 Practice for Calculating Yellowness and Whiteness
Practice E29.
Indices from Instrumentally Measured Color Coordinates
1.5 The values stated in SI units are to be regarded as
E691 Practice for Conducting an Interlaboratory Study to
standard. No other units of measurement are included in this
Determine the Precision of a Test Method
standard. E1455 Practice for Obtaining Colorimetric Data from a
Visual Display Unit Using Tristimulus Colorimeters
1.6 This standard does not purport to address all of the
2.2 Other Document:
safety concerns, if any, associated with its use. It is the
OSHA Regulations, 29 CFR paragraphs 1910.1000 and
responsibility of the user of this standard to establish appro-
1910.1200
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. For specific hazard
3. Summary of Test Method
statements, see Section 8.
3.1 The color of a liquid sample is measured as the
difference between the tristimulus values for the light trans-
mitted through the sample minus the tristimulus values for the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction of ASTM Committee D16 on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of Standards volume information, refer to the standard’s Document Summary page on
Subcommittee D16.04 on Instrumental Analysis. the ASTM website.
Current edition approved Dec. 1, 2016. Published January 2017. Originally AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments,
approved in 1993. Last previous edition approved in 2010 as D5386 – 10. DOI: 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
10.1520/D5386-16. www.access.gpo.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5386 − 16
light transmitted through the same path length of water 6.4 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-
(Specification D1193, Type IV). The difference between the chloric acid (HCl).
tristimulus values are used to calculate the color on the Pt-Co
6.5 Potassium Chloroplatinate, (K PtCl ).
2 6
scale using the appropriate equations.
6.6 Platinum-Cobalt Stock Solution—Dissolve 1.245 g of
4. Significance and Use potassium chloroplatinate (K PtCl ) and 1.00 g of cobalt
2 6
chloride (CoCl ·H O) in water. Carefully add 100 mL of
2 2
4.1 The primary objective of the visual method of Pt-Co
hydrochloric acid (HCl) and dilute to 1 L with water. The
colormeasurement,asdefinedinTestMethodD8005,istorate
absorbance measured for the number 500 Pt-Co stock solution
specificmaterialsforyellowness.Thisyellownessisfrequently
in a cell having a 10-mm path length, using a cell of the same
theresultoftheundesirabletendencyofliquidhydrocarbonsto
pathlengthcontainingwaterasthereferencesolution,mustfall
absorbbluelightduetocontaminationinprocessing,storageor
within the limits given in Table 1.
shipping.
4.2 Clear liquids can be rated for light absorbing yellowish
TABLE 1 Absorbance Tolerance Limits for Number 500 Platinum-
or brownish contaminants using scales that simulate the
Cobalt Stock Solution
long-established visual-comparison method.
Wavelength Absorbance
430 0.110 to 0.120
5. Apparatus
455 0.130 to 0.145
480 0.105 to 0.120
5.1 Instrument, with the following provisions:
510 0.055 to 0.065
5.1.1 Instrument Sensor, shall measure the light transmitted
through a liquid sample in a cell as described in Guide E179.
Theinstrumentshallbecapableofconvertingthemeasurement
7. Materials
to CIE X Y Z tristimulus values for CIE illuminant C and the
7.1 Platinum-Cobalt Standards—From the Pt-Co stock
CIE 1931 2-degree standard observer as described in Practice
E308. solution,preparecolorstandardsinaccordancewithTable2by
diluting the required volumes to 100 mL with water in
5.1.2 Thedifferencebetweenthetristimuluscolorvaluesfor
the sample and water shall be converted to the instrumental volumetricflasks.Pt-Cocolorstandardswithhighervaluescan
be prepared by using proportionally greater volumes of the
yellowness index (YI) defined by Practice E313.Acorrelation
between measured YI values and the Pt-Co color standard stock solution. When properly sealed and stored these stan-
dardsarestableforatleastoneyear.Pt-Cocolorstandardsmay
solutions shall be used to yield an equivalent instrumental
Pt-Co rating for liquid hydrocarbon samples. also be purchased.
5.2 Sample Cells, shall have clear, colorless, parallel en-
TABLE 2 Platinum-Cobalt Color Standards
trance and exit windows. The internal distance between the
Color Standard Color Standard
faces shall be user selectable. Path lengths from 20 to 150 mm
Stock Solution, mL Stock Solution mL
Number Number
have been used for near-clear liquid hydrocarbon samples.
1 0.20 10 2.00
When measuring samples using cells of the same path length,
2 0.40 11 2.20
a path length tolerance of 63 % or less would be appropriate.
3 0.60 12 2.40
4 0.80 13 2.60
Matched cells are preferred but not required.
5 1.00 14 2.80
6 1.20 15 3.00
6. Reagents
7 1.40 20 4.00
8 1.60 25 5.00
6.1 Purity of Reagents—Reagent grade chemicals shall be
9 1.80 30 6.00
used in all tests. Unless otherwise indicated, it is intended that
all reagents shall conform t
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D5386 − 10 D5386 − 16
Standard Test Method for
Color of Liquids Using Tristimulus Colorimetry
This standard is issued under the fixed designation D5386; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*Scope
1.1 This test method covers an instrumental method for the CIE (Commission International de l’Eclairage)l’Eclairage)
tristimulus measurement of the color of near-clear liquid samples. The transmission measurement is values are converted to the
color ratingsscale in the platinum-cobalt (Pt-Co) system.
1.2 This test method has been found applicable to the color measurement of clear, liquid samples, free of haze, with nominal
platinum cobalt Pt-Co color values in the 0 to 100 range. It is applicable to nonfluorescentnon-fluorescent liquids with light
absorption characteristics similar to those of the platinum cobalt Pt-Co color standard solutions. Test Methods D1686, D2108, and
E450 deal with the visual and instrumental measurement of near-clear liquids.
1.3 The tristimulus colorimetry may be calculated from spectral measurements or be obtained directly from a colorimeter.
Practice E1455 provides some guidance on colorimeters, while Test Methods D1686 and D2108 deal with the visual and
instrumental measurement of near-clear liquids.
1.4 In determining the conformance of the test results using this method to applicable specifications, results shall be rounded
in accordance with the rounding off methods of Practice E29.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use. For specific hazard statements, see Section 8.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D1209 Test Method for Color of Clear Liquids (Platinum-Cobalt Scale)
D1686 Test Method for Color of Solid Aromatic Hydrocarbons and Related Materials in the Molten State (Platinum-Cobalt
Scale)
D2108 Test Method for Color of Halogenated Organic Solvents and Their Admixtures (Platinum-Cobalt Scale)
D3437 Practice for Sampling and Handling Liquid Cyclic Products
D6809 Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials
D8005 Test Method for Color of Clear Liquids (Platinum-Cobalt Scale)
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E179 Guide for Selection of Geometric Conditions for Measurement of Reflection and Transmission Properties of Materials
E308 Practice for Computing the Colors of Objects by Using the CIE System
E313 Practice for Calculating Yellowness and Whiteness Indices from Instrumentally Measured Color Coordinates
E450 Test Method for Measurement of Color of Low-Colored Clear Liquids Using the Hunterlab Color Difference Meter
(Withdrawn 1993)
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E1455 Practice for Obtaining Colorimetric Data from a Visual Display Unit Using Tristimulus Colorimeters
This test method is under the jurisdiction of ASTM Committee D16 on Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of Subcommittee
D16.04 on Instrumental Analysis.
Current edition approved Jan. 1, 2010Dec. 1, 2016. Published January 2010January 2017. Originally approved in 1993. Last previous edition approved in 20052010 as
D5386 – 05.D5386 – 10. DOI: 10.1520/D5386-10.10.1520/D5386-16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5386 − 16
2.2 Other Document:
OSHA Regulations, 29 CFR paragraphs 1910.1000 and 1910.1200
3. Summary of Test Method
3.1 Color is measured by tristimulus values of light transmitted by a sample as percent of light transmitted by distilled water.
Convert the measured The color of a liquid sample is measured as the difference between the tristimulus values for the light
transmitted through the sample minus the tristimulus values for the light transmitted through the same path length of water
(Specification D1193tristimulus values by appropriate equations to the platinum-cobalt scale., Type IV). The difference between
the tristimulus values are used to calculate the color on the Pt-Co scale using the appropriate equations.
4. Significance and Use
4.1 The majorprimary objective of the visual platinum-cobalt (Pt-Co) method of Pt-Co color measurement, as defined in Test
Method D1209D8005, is to rate specific materials for yellowness. This yellowness is frequently the result of the undesirable
tendency of liquid hydrocarbons to absorb blue light due to contamination in processing, storage or shipping.
4.2 Clear liquids can be rated for light absorbing yellowish or brownish contaminants,contaminants using scales that simulate
the long-established visual-comparison method just cited. Where needed, dimensions of color can be reported to identify any
pinkness or greenness (one dimension), or grayness.method.
5. Apparatus
5.1 Instrument, with the following provisions:
5.1.1 Instrument Sensor, shall provide a beam for illuminating the sample cell in transmission.measure the light transmitted
through a liquid sample in a cell as described in Guide E179. The instrument shall be capable of converting light measured in total
transmission through the sample cell the measurement to CIE X Y Z tristimulus color values for the measurement conditions of
CIE illuminant C and the CIE 1931 2 degree 2-degree standard observer as described in Guide E179 and Practice E308.
5.1.2 The CIE X Y Z difference between the tristimulus color values for the sample and water shall be convertibleconverted to
the instrumental yellowness index (YI) defined by Practice E308 and Practice E313. A correlation between measured yellowness
index (YI) (Practice YI E313) values and the Pt-Co color standard solutions shall be used to yield an equivalent instrumental Pt-Co
rating for liquid hydrocarbon samples.
5.1.3 Sample Cells, shall have clear, colorless, parallel entrance and exit windows. Internal distance between faces shall be
selectable. Path lengths from 20 to 150 mm have been used for near-clear liquid hydrocarbons. If measuring samples using cells
of the same path length, a path length tolerance of 63 % or less would be appropriate. Matched cells would be beneficial but not
required.
5.2 Sample Cells, shall have clear, colorless, parallel entrance and exit windows. The internal distance between the faces shall
be user selectable. Path lengths from 20 to 150 mm have been used for near-clear liquid hydrocarbon samples. When measuring
samples using cells of the same path length, a path length tolerance of 63 % or less would be appropriate. Matched cells are
preferred but not required.
6. Reagents
6.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
6.2 Purity of Water—References to water shall be understood to mean clear, colorless distilled water, conforming to Type IV
of Specification D1193.
6.3 Cobalt Chloride, (CoCl ·6H O).
2 2
6.4 Hydrochloric Acid (sp gr 1.19)—Concentrated hydrochloric acid (HCl).
6.5 Potassium Chloroplatinate, (K PtCl ).
2 6
6.6 Platinum-Cobalt Stock Solution—Dissolve 1.245 g of potassium chloroplatinate (K PtCl ) and 1.00 g of cobalt chloride
2 6
(CoCl H·H O) in water. Carefully add 100 mL of hydrochloric acid (HCl sp gr 1.19) (HCl) and dilute to 1 L with distilled water.
2 2
Available from U.S. Government Printing Office Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
www.access.gpo.gov.
Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
D5386 − 16
The absorbance of measured for the number 500 platinum-cobaltPt-Co stock solution in a cell having a 10-mm light path with
distilled water in a matched cell path length, using a cell of the same path length containing water as the reference solution, must
fall within the limits given in Table 1.
TABLE 1 Absor
...