NB/SH/T 0415-2013 Determination of ultraviolet absorbance and absorptivity of petroleum products

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1. Method number / full title / English title / replacement relationship

• Standard number: NB/SH/T 0415—2013 (cover page source-text extraction shows "NB/SHVT 0415—2013", page header shows "NB/SH/T 0415—2013", the page header shall prevail; requires confirmation against the source standard (source-text extraction))
• Chinese title: Determination of ultraviolet absorbance and absorptivity of petroleum products
• English title: Standard test method for ultraviolet absorbance and absorptivity of petroleum products (original text reads "uiltraviolet", requires confirmation against the source standard (source-text extraction))
• Replacement relationship: replaces SH/T 0415—1992 "Test method for ultraviolet absorbance of petroleum products"; SH/T 0415—1992 was developed by equivalent adoption of ASTM D 2008-80
• Adoption relationship: modified adoption using the redrafting method of ASTM D 2008-09
• Publication/implementation: published on 2013-06-08, implemented on 2013-10-01
• Issuing body: National Energy Administration
• Secretariat: Subcommittee on Petroleum Wax Products of the National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC 280/SC3)
• Drafting organization: Fushun Research Institute of Petroleum and Petrochemicals, China Petroleum & Chemical Corporation
• Main drafters: Zhao Bin, Gao Jian
• First publication: year 1992, this is the first revision

2. Scope of application and non-applicability

• This standard specifies the method for determination of ultraviolet absorbance and absorptivity of petroleum products.
• It is applicable to the determination of ultraviolet absorption of various petroleum products at wavelengths in the spectral region 220nm~400nm, including the absorbance of liquid samples, or the absorptivity of liquid and solid samples.
• It is used under specified measurement conditions, which include wavelength, solvent (if used), sample path length and sample concentration; when using it, refer to the application examples in the appendix of this standard, or other descriptions of measurement conditions.
• Application examples include: determination of the absorbance of white oil, the absorptivity of refined petroleum wax, and the absorptivity of pharmaceutical petrolatum, etc.
• Not applicable: no explicit "not applicable" clause is provided in the available source.

3. Method principle

• Under specified conditions, the ultraviolet absorbance of a liquid sample is determined by measuring its absorbance using an absorption cell of known path length.
• At a specified wavelength, the ultraviolet absorptivity of a liquid or solid solution is determined by measuring the absorbance of a solution of known concentration using an absorption cell of known path length.
• Significance and use: in characterizing petroleum products, the absorptivity of liquids and solids at specified ultraviolet wavelengths is useful.

4. Reagents and materials (purity / preparation)

• Water: shall meet the requirements for grade three water in GB/T 6682.
• Isooctane (Warning: extremely flammable, harmful if inhaled): analytical reagent, as the preferred spectroscopic solvent. When the purity does not meet the requirements, purify according to the following procedure: take 4L~5L isooctane and percolate through an activated silica gel column of diameter 50mm~75mm and height (original value missing, requires confirmation against the source standard (source-text extraction)). Use a 1.0cm absorption cell, with water as reference, and detect in the wavelength range 240nm~300nm, collecting the effluent with absorbance less than 0.05.
• Decalin (the chemical name is unclear in the source transcription; its interpretation as decalin remains unverified; Warning: flammable, vapors harmful): analytical reagent, as the preferred alternative spectroscopic solvent. When the purity does not meet the requirements, it is also recommended to prepare decalin spectroscopic solvent by the silica gel percolation method described in 7.2.
• Commercial "spectroscopically pure" solvents listed in ASTM E169 may be used. One of them may be selected for the determination of absorptivity, but only for use according to 9.2.2 (original text reads "92.2", requires confirmation against the source standard (source-text extraction)).
• Holmium oxide glass or holmium oxide solution: used to check the wavelength accuracy of the spectrophotometer.
• Alternative solvents (see 9.2.2.4): cyclohexane (Warning: extremely flammable, harmful if inhaled), carbon tetrachloride, chloroform (Warning: carbon tetrachloride and chloroform are fatal if swallowed, harmful if inhaled, and burning produces toxic vapors) and ethanol, etc.

5. Apparatus and equipment

• 6.1 Spectrophotometer: equipped with absorption cells for liquid samples with path length not greater than 10cm, capable of measuring absorbance within 220nm~400nm using a spectral bandwidth of 2nm or smaller. Wavelength repeatable, with precision ±0.2nm or smaller. At absorbance 0.4 within 220nm~400nm, absorbance repeatability is (original value missing, requires confirmation against the source standard (source-text extraction)). Wavelength accuracy check: measure absorption with holmium oxide solution at 287.1nm, or at the mercury emission line 241.16nm (original text reads ".16nm", requires confirmation against the source standard (source-text extraction)), or at 287.5nm using holmium oxide glass or at (original missing, requires confirmation against the source standard (source-text extraction)).
• 6.2 For the spectrophotometer method used in this standard, see JB/T 6777.
• 6.3 Instruments that can give (original missing, requires confirmation against the source standard (source-text extraction)) results may also be used.
• 6.4 Absorption cells with path length less than (original missing, requires confirmation against the source standard (source-text extraction)) may only be used on the instrument equipped with such cells. When extending the spectral range, the spectrophotometer shall be (original missing, requires confirmation against the source standard (source-text extraction)). An automatic recorder is recommended; a manually operated spectrophotometer is more suitable for obtaining absorbance readings at specified analytical wavelengths. When the temperature is above room temperature, measures shall be taken to ensure that the absorption cell is tested at the selected temperature.
• 6.5 Fused quartz absorption cells: one or more pairs, path length 0.1000cm~10.00cm, and shall be within ±0.5% of their nominal path length. Unless otherwise specified, absorption cells of path length 1.0cm are recommended. For inspection and cleaning procedures of absorption cells, see JB/T 6777.

6. Recommended operating conditions

• Spectral region: 220nm~400nm.
• Spectral bandwidth: 2nm or smaller (see 6.1).
• Wavelength accuracy: ±0.2nm or smaller (see 6.1).
• Recommended sample path length: 1.0cm; alternative sample path length: 10.0cm (see 9.2.4.1).
• Optimum absorbance reading range: 0.1~1.0 (see 9.2.1.2).
• Upper limit of high-temperature test temperature: shall not exceed 66℃ (see 9.2.6.1); during testing, the solution temperature shall be maintained within ±1.1℃ of the test temperature (see 9.2.6.5).
• Solvent: isooctane is preferred; if it cannot completely dissolve the sample, use decalin; if the solubility is low in both, select from the list in ASTM E169 (see 9.2.2).

7. Sampling and sample preparation

• Ultraviolet absorption is very sensitive to small amounts of foreign contaminants introduced by improper handling, so precautions shall be taken and sampling shall be carried out carefully to (original missing, requires confirmation against the source standard (source-text extraction)) the sample. If possible, samples should be taken from packaged products to prevent accidental contamination.
• For the petroleum product under test with a mass greater than 1kg, a representative sample of about 1kg shall be taken and mixed uniformly.
• For the petroleum product under test with a mass between 100g~1kg, the entire quantity shall be taken as the sample and mixed uniformly.
• For a petroleum product with a mass less than 100g, the sample is considered not representative. Testing may also be carried out, but when reporting the test results, the sample source, sampling procedure and basis for sample selection shall be recorded and reported as part of the results.
• Undiluted liquid sample: after sufficient dehydration, fill the 1.0cm sample absorption cell (see 9.1.2).
• Preparation of solid and liquid sample solutions: weigh the recommended mass of sample according to Table 1 into a volumetric flask, add solvent to half the volume, shake to dissolve, then add solvent to the mark and mix well; if it cannot dissolve quickly, it may be heated in a water bath to dissolve, and after cooling to room temperature, add solvent to the mark (see 9.2.5.1, 9.2.5.2).
• Preparation of samples for high-temperature operation: weigh accurately to 0.1mg, add to a clean and calibrated volumetric flask, add part of the solvent, then place in a water bath at the same temperature as the test temperature; after complete dissolution, dilute to the mark with solvent at the same temperature, mix well and heat to the test temperature (see 9.2.6.2, 9.2.6.3).

8. Analytical procedure

8.1 Absorbance of undiluted liquid sample (9.1)

• 9.1.1 Fill 1.0cm (reference absorption cell) with water, and measure the absorbance at the analytical wavelengths in the wavelength range 220nm~400nm to determine the correction value of the 1.0cm absorption cell. If its absorbance throughout the wavelength region is between -0.01~+0.01, the correction value may be neglected. After determining the correction value of the absorption cell, the reference absorption cell and the sample absorption cell shall be fixed and kept unchanged during the test.
• 9.1.2 Fill the 1.0cm sample absorption cell with the undiluted liquid sample (sufficiently dehydrated), and measure the absorbance according to 9.1.1.
• 9.1.3 Plot the absorbance-wavelength curve starting from the long-wavelength end of the spectrum. Read absorbance data sequentially from the shorter wavelength until a value greater than 1.0 is obtained. When using an automatic recorder (recommended), it is best to plot the correction scan of the absorption cell and the scan of the sample on the same chart. For the longer wavelength region of the spectrum, in order to obtain easily readable absorbance, it is best to use an absorption cell with a path length greater than the recommended length (see the application section in ASTM E169). For the shorter wavelength region of the spectrum, the absorbance will be larger. For accurate measurement, a 0.1cm absorption cell may be used. Record only when these absorbance values are greater than 1.0. If numerical expression is required, determination of absorptivity is recommended.
• 9.1.4 If a 0.1cm absorption cell is used instead of a 1.0cm absorption cell (9.1.3), repeat the procedures in 9.1.1 and 9.1.2, and record all measurement results.

8.2 Absorptivity of solid and liquid samples (9.2)

• 9.2.1 Method summary: the absorptivity of petroleum products covers a very wide range, with the most commonly used range between 10~(original unit missing, requires confirmation against the source standard (source-text extraction))L/(g·cm)~10(original missing, requires confirmation against the source standard (source-text extraction))L/(g·cm). When determining absorptivity, to obtain the best results, the absorbance value should be between 0.1~1.0. By preparing solutions or selecting the sample cell path length, an absorbance between 0.1~1.0 can be obtained. The absorptivity of individual petroleum products may vary greatly with wavelength; in order to cover the required wavelength range, several different sample solutions should be prepared. To obtain reliable results, the selection of solvent, concentration and sample cell path length should be considered.
• 9.2.2 Selection of solvent: depends on the solubility of the petroleum product and the transmittance of the solvent at the analytical wavelength; see the brief discussion on solvents for ultraviolet use in the application sections of ASTM E169. Unless limited by solubility, isooctane should be selected as the solvent. If the sample cannot be completely dissolved in isooctane, decahydronaphthalene may be used instead as the solvent. If, when preparing the required solution, the sample has low solubility in both isooctane and decahydronaphthalene, then a solvent may be selected from the list in ASTM E169. Not all listed solvents are suitable for all spectral regions involved in this method. Over the entire wavelength region in which the absorbance of the test sample is measured, using a 1.0cm absorption cell and water as reference, measure the absorbance of a solvent; when the absorbance is less than 0.05, the solvent is considered to have sufficient "spectral purity".
• 9.2.3 Selection of solution concentration: at the wavelength of weakest absorption, the concentration of the original sample solution should be sufficient to provide a moderate absorbance (0.1~1.0), but must not exceed 40g/L, and must be within the limit of solubility of the solvent. From the original solution, a minimum concentration of about 1g/L can be prepared. If the sample does not dissolve completely at room temperature, the dissolution temperature may be raised and then proceed according to 9.2.5. Table 1 lists the recommended concentrations of four original solutions, the required sample mass, and the solution volume, and in the fourth column gives the range of absorption coefficients measurable with a 1.0cm absorption cell when the absorbance is between 0.1~1.0. Select the required concentration according to the minimum absorption coefficient of the sample in Table 1. If, because the absorption coefficient at the analytical wavelength is greater than 1, a concentration less than 1g/L solution is required, first prepare an original solution with a concentration of 4g/L (see Table 1), and dilute as follows: pipette 1mL~10mL of the original solution into a 25mL~100mL volumetric flask to obtain a dilution factor between 2.5~100. Select an appropriate dilution factor to obtain an absorbance reading of 0.1~1.0 at the analytical wavelength.
  • Note: For example, pipette 1mL 4g/L of the original solution into a 25mL volumetric flask, add solvent to the mark, and mix well. The dilution factor of the first dilution is 25, and the concentration is 0.160g/L. Repeat the above procedure; from the first dilution, a dilution with a concentration of 0.064g/L can be prepared. The dilution factor of the second dilution is 625.
• 9.2.4 Selection of sample path length: unless otherwise specified in individual applications of this method, the recommended sample path length is 1.0cm, and the alternative sample path length is 10.0cm. In 9.2.5, 9.2.6, the recommended 1.0cm sample path length is specified, and the alternative sample path length is 10.0cm. In individual applications of this method, different sample path lengths are specified, but the smaller sample path length should use the recommended 1.0cm absorption cell, and the alternative larger sample path length should use the 10.0cm absorption cell.
• 9.2.5 Procedure at room temperature: weigh different recommended masses of sample into a volumetric flask (see Table 1), add solvent to the volumetric flask to half of its volume, shake to dissolve, then add solvent to the mark and mix well. If the sample does not dissolve rapidly, the volumetric flask may be placed in a water bath and heated to dissolve. After the sample has dissolved, add solvent to dilute and mix well. After cooling to room temperature, add solvent to the mark. Fill a 1.0cm sample absorption cell with the original solution or diluted solution to be tested, fill a 1.0cm reference absorption cell with solvent, ensure the cell windows are clean, then place the cells in the cell compartment of the spectrophotometer, and measure the absorbance of the sample at the analytical wavelengths in the region 220nm~400nm. If, using a 1.0cm absorption cell, the absorbance readings at one or more analytical wavelengths are all less than 0.1, then switch to a 10.0cm absorption cell and repeat the 9.2.5.3 procedure to obtain absorbance readings between 0.1~1.0. If, using a 1.0cm absorption cell, the absorbance readings at one or more analytical wavelengths are all greater than 1.0, then dilute the original solution. That is, pipette 1mL~10mL of the original solution into a 25mL~100mL volumetric flask, and add solvent to the mark. Repeat the 9.2.5.3 procedure to obtain absorbance readings between 0.1~1.0. Measure the absorbance of a sample absorption cell filled with solvent and a reference absorption cell filled with solvent, and determine the correction value of the absorption cells by comparison.
• 9.2.6 Procedure at elevated temperature: if a uniform sample solution cannot be obtained at room temperature with the recommended solvent (9.2.5.2), it is permissible to measure absorbance at a higher temperature at which the sample can be dissolved, but it must not exceed 66℃. Weigh different recommended sample amounts, accurate to 0.1mg (see Table 1), and add to a clean and calibrated volumetric flask. Add part of the solvent to the volumetric flask, and place the volumetric flask in a water bath at the same temperature as the test temperature. After the sample is completely dissolved, dilute to the mark with solvent at the same temperature as the test temperature, mix well, and heat in the water bath to the test temperature. Prepare a thermostatic device for the spectrophotometer absorption cells so that the sample absorption cell and reference absorption cell are maintained at the required test temperature. Appropriate measures should be taken to ensure that the temperature of the solution during testing is maintained within ±1.1℃ of the test temperature. Using a syringe (preheated to the test temperature), inject the sample solution into a 1.0cm sample absorption cell preheated to the test temperature. In the same manner, preheat to the test temperature (missing in the source text, requires confirmation against the source standard (source-text extraction)) into the cm reference absorption cell, close the cell cover tightly, wipe the cell windows clean, then place the cells in the spectrophotometer (missing in the source text, requires confirmation against the source standard (source-text extraction)) for sufficient time to allow temperature equilibration, and measure absorbance at the analytical wavelengths in the region 220nm~400nm. If, using a 1.0cm absorption cell, the absorbance readings at one or more analytical wavelengths are all less than 0.1, then switch to a 10.0cm absorption cell and repeat the 9.2.6.6 procedure to obtain absorbance readings between 0.1~1.0. If, using a 1.0cm absorption cell, the absorbance readings at one or more analytical wavelengths are all greater than 1.0, then prepare a second original solution of lower concentration according to Table 1. If the requirements are still not met, then switch to a pair of 0.1cm or 0.5cm absorption cells and repeat the 9.2.6.6 procedure to obtain absorbance readings between 0.1~1.0. Record all readings. Measure the absorbance of a sample absorption cell filled with solvent and a reference absorption cell filled with solvent, and determine the correction value of the absorption cells by comparison.

Table 1 Recommended sample mass and solution volume for sample original solutions

Note: *The sample is weighed accurate to within 0.1mg or within ±5% of the nominal mass in the table. Note: **If a 10.0cm absorption cell is used, divide the range of absorption coefficients by 10.

9. Qualitative and quantitative determination and calculation formulas

• 10.1 Absorbance of liquid sample: the absorbance of the undiluted liquid sample at each analytical wavelength is calculated according to formula (4):
  • A = A_s − A_r (formula 4, original formula source-text extraction missing, arranged according to the meaning of the text, requires confirmation against the source standard (source-text extraction))
  • Where: A—— absorbance of the undiluted liquid sample; A_s—— absorbance of the sample absorption cell filled with sample or the reading on the scan; A_r—— absorbance of the sample absorption cell filled with water or the reading on the scan.
  • Absorbance per unit centimeter path length A/l, where l is the path length of the sample absorption cell expressed in cm.
• 10.2 Absorption coefficient of solid and liquid samples: the absorption coefficient of the sample at the analytical wavelength is a, calculated by formula (5):
  • a = A/(b·c) (formula 5, original formula source-text extraction missing, arranged according to the meaning of the text, requires confirmation against the source standard (source-text extraction))
  • Where: b—— absorption cell path length, cm; c—— concentration of the solution (original unit missing, requires confirmation against the source standard (source-text extraction)); f—— dilution factor, i.e., the ratio of the volume of the diluted solution to the volume of the original solution containing the same solute that was diluted.
• Definition of terms (Chapter 3):
  • 3.1 Radiant energy: energy transmitted in the form of electromagnetic waves.
  • 3.2 Radiant power P: the rate at which energy is transmitted in a beam of radiant energy.
  • 3.3 Transmittance T: a molecular property indicating the ability of a substance to transmit radiant power, T = P/P₀ (formula 1). Where P—— radiant power transmitted by the sample; P₀ — radiant power incident on the sample.
  • 3.4 Absorbance A: A = lg(1/T) = −lgT (formula 2). Note: Absorbance is (missing in the source text, requires confirmation against the source standard (source-text extraction)); attenuation relative to absorption, losses due to reflection, solvent absorption, and refraction effects have been compensated for, and that caused by scattering (missing in the source text, requires confirmation against the source standard (source-text extraction)).
  • 3.5 Dilution factor f: represents the ratio of the volume of the original solution containing the same solute (missing in the source text, requires confirmation against the source standard (source-text extraction)).
  • 3.6 Absorption coefficient a: the property of a substance to absorb radiant energy at unit concentration and unit path length, a expressed by formula (3) (original formula missing, requires confirmation against the source standard (source-text extraction)).
  • 3.7 (missing in the source text, requires confirmation against the source standard (source-text extraction))
  • 3.8 Path length: in the direction of propagation of the radiant energy beam, the distance from the sample surface where radiant energy enters to the sample surface where radiant energy exits, expressed in cm; the length does not include the thickness of the absorption cell containing the sample.

10. Precision

• 12.1 Precision: four specific (for precision of application examples, see A.5 (white oil), B.5 (refined petroleum wax), C.5 (pharmaceutical petrolatum), and D.5 (environmentally friendly rubber processing (oil))). Other petroleum products (precision) are determined through interlaboratory cooperation by testing representative samples.
• 12.2 Bias: Because there is no acceptable reference standard, the bias of these steps cannot be determined.

Appendix A (Normative Appendix) Absorbance of White Oil

• A.1 Scope: This is one of the examples of applying the general method to determine the absorbance of undiluted liquid samples. The absorbance of white oil should be tested at 275nm using a 0.1cm absorption cell, and at 295nm~299nm and 300nm~400nm using a 1.0cm absorption cell.
• A.2 Procedure: For the absorbance test of white oil samples, operate according to the steps in 9.1, scanning in the region of 400nm~250nm.
• A.3 Calculation: Calculate according to clause 10.1.1 the absorbance of the sample measured with a 0.1cm absorption cell at 275nm, and the maximum absorbance in the regions 295nm~299nm and 300nm~400nm measured with a 1.0cm absorption cell.
• A.4 Report: Report the absorbance of white oil as follows, retaining 3 decimal places:

• A.5 Precision and Bias
  • A.5.1 Precision of interlaboratory test results obtained by statistical methods (95% confidence level).
  • A.5.1.1 Repeatability: The difference between consecutive test results obtained by the same operator using the same instrument, under stable operating conditions, on the same sample correctly operated according to this method, shall not exceed the following values:

• A.5.1.2 Reproducibility: The difference between two separate test results obtained by different operators in different laboratories, on the same sample correctly operated according to this method, shall not exceed the following values:

• A.5.2 Bias: Because there is no acceptable standard, the bias of this step cannot be determined.

Appendix B (Normative Appendix) Absorptivity of Refined Petroleum Wax

• B.1 Scope: This is one of the examples of applying the general method to determine the absorptivity of solid and liquid samples. The absorptivity of refined petroleum wax is tested at a wavelength of 290nm. Under the specified conditions, this method is suitable for determining absorptivity in the range of 0.01L/(g·cm)~1.0L/(g·cm).
• B.2 Procedure: Test the absorptivity of refined petroleum wax at room temperature according to the general method given in 9.2.5. It is recommended to dissolve a 100mg refined petroleum wax sample in (volume missing in the source text, requires confirmation against the source standard (source-text extraction)) isooctane, using 1.0cm and 10.0cm absorption cells, and measure the absorbance at a wavelength of 290nm according to 9.2.3. If the sample does not completely dissolve in isooctane, use decalin as the solvent. If the sample does not completely dissolve in isooctane or decalin at room temperature, proceed according to 9.2.6.
• B.3 Calculation: Calculate the absorptivity of petroleum wax a (formula missing in the source text, requires confirmation against the source standard (source-text extraction)).
• B.4 Report: Report the absorptivity of petroleum wax in the range of 0.01L/(g·cm)~1.0L/(g·cm), retaining two significant figures. If less than 0.01L/(g·cm), report the result as less than 0.01L/(g·cm); if greater than 1.0L/(g·cm), report the result as greater than 1.0L/(g·cm).
• B.5 Precision and Bias
  • B.5.1 Precision of interlaboratory test results obtained by statistical methods.
  • B.5.1.1 Repeatability: The difference between consecutive test results obtained by the same operator using the same instrument, under stable operating conditions, on the same sample correctly operated according to this method, shall not exceed the following values:

• B.5.1.2 Reproducibility: The difference between two separate test results obtained by different operators in different laboratories, on the same sample correctly operated according to this method, shall not exceed the following values:

• B.5.2 Bias: Because there is no acceptable standard, the bias of this step cannot be determined.

Appendix C (Normative Appendix) Absorptivity of Medicinal Petrolatum

• C.1 Scope: As one of the examples of applying the general method to determine the absorptivity of solid and liquid samples, the absorptivity of medicinal petrolatum should be tested at a wavelength of 290nm. Under the specified conditions, this method is suitable for determining absorptivity in the range of 0.02L/(g·cm)~5.0L/(g·cm).
• C.2 Procedure: Test the absorptivity of medicinal petrolatum at room temperature according to the general method given in 9.2.5. It is recommended to dissolve a 100mg medicinal petrolatum sample in 100mL isooctane, using 1.0cm and 10.0cm absorption cells, and measure the absorbance at a wavelength of 290nm according to 9.2.5. If dilution according to 9.2.5.5 is required, a dilution factor of 5 (e.g., diluting from 5mL to 25mL) is suitable for determining absorptivity up to a maximum of 5.0L/(g·cm). If the sample does not completely dissolve in isooctane, use decalin as the solvent. Note: Carbon tetrachloride (Warning: May be fatal if swallowed, harmful if inhaled, combustion can produce toxic vapors) is also a good solvent for many petrolatums. When the sample does not completely dissolve in decalin, carbon tetrachloride can be used as the solvent.
• C.3 Calculation: The absorptivity a of medicinal petrolatum at a wavelength of 290nm is calculated according to formula (5).
• C.4 Report: Report the absorptivity of medicinal petrolatum in the range of 0.02L/(g·cm)~5.0L/(g·cm), retaining two significant figures. If less than 0.02L/(g·cm), report the absorptivity as less than 0.02L/(g·cm); if greater than 5.0L/(g·cm), report the absorptivity as greater than 5.0L/(g·cm).
• C.5 Precision and Bias
  • C.5.1 Precision of interlaboratory test results obtained by statistical methods (95% confidence level).
  • C.5.1.1 Repeatability: The difference between consecutive test results obtained by the same operator using the same instrument, under stable operating conditions, on the same sample correctly operated according to this method, shall not exceed 0.01L/(g·cm).
  • C.5.1.2 Reproducibility: The difference between two separate test results obtained by different operators in different laboratories, on the same sample correctly operated according to this method, shall not exceed 0.05L/(g·cm).
  • C.5.2 Bias: Because there is no acceptable standard, the bias of this step cannot be determined.

Appendix D (Normative Appendix) Absorptivity of Environmentally Friendly Rubber Processing or Extending Oil

• D.1 Scope: This is one of the examples of applying the general method to determine the absorptivity of solid and liquid samples. The absorptivity of environmentally friendly rubber processing and its extending oil is tested at a wavelength of 260nm. Under the specified conditions, this method is suitable for determining absorptivity in the range of 0.10L/(g·cm)~20L/(g·cm).
• D.2 Procedure: Test the absorptivity of environmentally friendly rubber processing and its extending oil at room temperature according to the general method given in 9.2.5. It is recommended to dissolve a 100mg sample in 100mL "spectroscopic grade" isooctane, using a 1.0cm absorption cell, and measure the absorbance at a wavelength of 260nm according to 9.2.5. If dilution according to 9.2.5.5 is required, a dilution factor of 5 (e.g., diluting from 5mL to 25mL) is suitable for determining absorptivity below 5.0L/(g·cm), and a dilution factor of 20 (e.g., diluting from 5mL to 100mL) is suitable for determining absorptivity between 5.0L/(g·cm)~20L/(g·cm).
• D.3 Calculation: The absorptivity a of the environmentally friendly rubber processing and its extending oil sample at a wavelength of 260nm is calculated according to formula (5).
• D.4 Report: Report the absorptivity of the sample in the range of 0.10L/(g·cm)~20L/(g·cm), retaining two significant figures. If less than 0.10L/(g·cm), report the absorptivity as less than 0.10L/(g·cm); if greater than 20L/(g·cm), report the absorptivity as greater than 20L/(g·cm).
• D.5 Precision and Bias
  • D.5.1 Precision: Use the following provisions to judge the reliability of test results (95% confidence level).
  • D.5.1.1 Repeatability: If the difference between parallel test results by the same operator is greater than 7% of the average, it is considered suspect.
  • D.5.1.2 Reproducibility: If the difference between results provided separately by two laboratories is greater than 9% of the average, it is considered suspect.
  • D.5.2 Bias: Because there is no acceptable standard, the bias of this step cannot be determined.

11. Report

• 11.1 Undiluted liquid samples:
  • 11.1.1 When reporting the (absorbance of the sample) value for undiluted liquid (missing in the source text, requires confirmation against the source standard (source-text extraction)), the measurement wavelength and the sample cell path length expressed as cm should be stated.
  • 11.1.2 When reporting the absorbance value per unit path length for an undiluted liquid sample, the measurement wavelength should be stated.
• 11.2 Absorptivity of solid and liquid samples: when reporting the absorptivity value, the wavelength at which absorbance is measured, solvent, concentration, and absorption cell path length shall be stated.
• The reporting requirements for each appendix are given in A.4, B.4, C.4, D.4.

12. Normative references

• GB/T 6682 Water for analytical laboratory use—Specification and test methods (GB/T 6682—2008, ISO 3696:1987, MOD) (original text reads “ISG 3696:1987”, requires confirmation against the source standard (source-text extraction))
• JB/T 6777 Ultraviolet-visible spectrophotometers
• ASTM E131 Terminology relating to molecular spectroscopy (Terminology Relating to Molecular Spectroscopy)
• ASTM E169 General technical regulations for ultraviolet-visible quantitative analysis (Practices for General Techniques of Ultraviolet-Visible Quantitative Analysis)
• ASTM D 2008-09 (the original standard modified for adoption)
• GB/T 1.1—2009 (drafting rules for this standard)

13. Source and verification

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14. Quick-reference Q&A