NB/SH/T 0655-2015 Test method for polycyclic aromatic hydrocarbons in petrolatum

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Card type: Test method

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

• Standard number: NB/SH/T 0655—2015
• Chinese title: Test method for polycyclic aromatic hydrocarbons in petrolatum
• English title: Standard test method for polycyclic aromatic hydrocarbons of vaseline
• Replacement relationship: replaces SH/T 0655—1998 "Test method for polycyclic aromatic hydrocarbons in petrolatum"
• Previous versions: SH/T 0655—1998
• Adoption relationship: modified adoption using the redrafting method of the test method for polycyclic aromatic hydrocarbons in the products White Petrolatum and Yellow Petrolatum (English version) in the British Pharmacopoeia BP-2012 edition
• Publication/implementation: published on 2015-10-27, implemented on 2016-03-01
• Issuing authority: National Energy Administration
• Drafting organization: Fushun Research Institute of Petroleum and Petrochemicals, China Petroleum & Chemical Corporation
• Drafters: Kang Geping, Cai Xiudang
• Secretariat: Subcommittee on Petroleum Wax Products of the National Technical Committee for Petroleum Products and Lubricants (SAC/TC280/SC3)
• Proposed by: China Petrochemical Corporation

Main differences from SH/T 0655—1998 (according to the foreword):

• Modified the "Method summary" chapter (see 3, 1998 edition's 3)
• Modified the "Normative references" chapter (see 2, 1998 edition's 2)
• Added "n-hexane is pre-treated twice with dimethyl sulfoxide, each time using 1/5 dimethyl sulfoxide reagent by volume of n-hexane" (see 7.1)
• Changed the wavelength measurement range from "265 nm～420 nm" to "260 nm～420 nm" (see 7.2, 1998 edition's 7.4)
• Changed the inspection of the dimethyl sulfoxide reagent from measuring transmittance to measuring absorbance (see 4.1, 1998 edition's 4.1)

Main differences from BP-2012 (according to the foreword): to adapt to China's national conditions and standard format, added chapters such as "Scope", "Normative references", "Method summary", "Reagents and materials", and "Apparatus"; refined the operating steps.

2. Scope of application and non-applicability

• This standard specifies the test method for polycyclic aromatic hydrocarbons in petrolatum.
• This standard applies to white petrolatum and yellow petrolatum products.
• Not applicable: not provided in the available source.

3. Method principle

Dissolve a 1.0 g sample in 50 mL n-hexane pre-treated with dimethyl sulfoxide; after two extractions with 20 mL dimethyl sulfoxide, back-extract the extract with 20 mL n-hexane, then dilute with dimethyl sulfoxide to 50 mL as the test solution; using n-hexane treated with dimethyl sulfoxide as the reference, measure the absorbance of the test solution in the wavelength range of 260 nm～420 nm, and compare the maximum absorbance with the absorbance of the naphthalene standard reference solution at 278 nm to judge whether the sample passes the polycyclic aromatic hydrocarbons test.

4. Reagents and materials (purity / preparation)

• 4.1 Dimethyl sulfoxide: (Warning: flammable, harmful if inhaled.) Spectroscopic grade, clear, water-white, content 99.9%, melting point 18.5 °C; using a 1 cm absorption cell with water as reference, the absorbance curve does not exceed 1.0 at 264 nm, and there are no extraneous impurity peaks in the wavelength range below 420 nm.
• 4.2 n-Hexane: (Warning: extremely flammable, harmful if inhaled.) Analytical reagent grade, boiling range 67 °C～69 °C; with water as reference, the minimum transmittance within 260 nm～420 nm is 97%. Before use, n-hexane must be pre-treated with dimethyl sulfoxide; each time, shake twice with dimethyl sulfoxide at 1/5 of the volume of n-hexane, allow to stand, and separate the n-hexane for use.
• 4.3 Naphthalene: (Warning: flammable, vapor harmful.) Analytical reagent grade, white crystals, melting point 81 °C. (The unit of "81°" in the source text requires confirmation against the source standard (source-text extraction))
• 4.4 Water: meets the grade-three water requirements in GB/T 6682.

5. Apparatus and equipment

• 5.1 Spectrophotometer: wavelength range 250 nm～450 nm, wavelength accuracy ±1 nm, absorbance accuracy ±0.01, equipped with quartz absorption cells of path length 1 cm and 4 cm.
• 5.2 Balance: accuracy 0.1 mg.
• 5.3 Pear-shaped separatory funnel: 100 mL, 125 mL.
• 5.4 Volumetric flask: 50 mL.
• 5.5 Graduated cylinder: 10 mL, 20 mL.
• Note: Do not apply any grease to ground-glass stoppers and stopcocks (see under the preparation items in 6).

6. Recommended operating conditions

Not provided in the available source (no separate "Recommended operating conditions" chapter; relevant operating conditions are scattered in Chapter 3, Chapter 6, and Chapter 7).

7. Sampling and sample preparation

• 7.1 Weigh a sample of 1.0 g (according to the method summary in Chapter 3; in Chapter 7 7.1, the source text "50 sample dissolved in 50 mL n-hexane" has source-text extraction missing characters, requires confirmation against the source standard (source-text extraction)); dissolve the sample in 50 mL n-hexane, transfer the solution to a 125 mL separatory funnel, add 20 mL dimethyl sulfoxide, shake vigorously, allow to stand until clear layers form, and transfer the lower layer solution (A) to another 125 mL separatory funnel.
• 7.2 To the extracted n-hexane solution, add 20 mL dimethyl sulfoxide, shake vigorously for 1 min, allow to stand until clear layers form, and put the lower dimethyl sulfoxide solution (B) into solution (A).
• 7.3 Add 20 mL n-hexane to the mixed solution of A and B, shake vigorously for 1 min, allow to stand until clear layers form, and dilute the lower layer with dimethyl sulfoxide to 50 mL as the test solution.
• 7.4 Take 20 mL dimethyl sulfoxide and mix with 25 mL n-hexane, shake vigorously for 1 min, allow to stand until clear layers form, take the clear lower layer as reference, and use a 4 cm absorption cell to measure the maximum absorbance of the test solution in the wavelength range of 260 nm～420 nm. (7.4: the extraction instruction for dimethyl sulfoxide is garbled; the stated volume of 20 mL remains unverified)

8. Analytical procedure

See Chapter 7 7.1～7.4.

Preparation work (Chapter 6):

• 6.1 Preparation of naphthalene standard reference solution for white petrolatum: prepare a 6.0 mg/L naphthalene solution in dimethyl sulfoxide.
• 6.2 Preparation of naphthalene standard reference solution for yellow petrolatum: prepare a 9.0 mg/L naphthalene solution in dimethyl sulfoxide.
• 6.3 Measurement of absorbance of naphthalene standard reference solutions for white and yellow petrolatum: with dimethyl sulfoxide as reference, use a 4 cm absorption cell to measure the maximum absorbance of the solution at 278 nm.
• Note: The naphthalene standard reference solutions for white and yellow petrolatum are valid for 6 months. When the maximum absorbance value of the sample test solution at 260 nm～420 nm is close to the maximum absorbance value of the naphthalene standard reference solutions for white and yellow petrolatum at 278 nm, making it difficult to judge whether the sample passes the polycyclic aromatic hydrocarbons test, the naphthalene standard reference solutions for white and yellow petrolatum must be re-prepared.

9. Qualitative and quantitative determination and calculation formulas

• Judgment rule (Chapter 8 Report): If the maximum absorbance of the white and yellow petrolatum test solutions within the wavelength range 260 nm～420 nm is not greater than the absorbance of the corresponding naphthalene standard reference solution at 278 nm, report the sample as "passing" the polycyclic aromatic hydrocarbons test; otherwise report "failing".
• Calculation formulas: not provided in the available source.

10. Precision

Not provided in the available source.

11. Report

If the maximum absorbance of the white and yellow petrolatum test solutions within the wavelength range 260 nm～420 nm is not greater than the absorbance of the corresponding naphthalene standard reference solution at 278 nm, report the sample as "passing" the polycyclic aromatic hydrocarbons test; otherwise report "failing".

12. Referenced documents

• GB/T 6682 Specifications and test methods for water for analytical laboratory use
• GB/T 1.1—2009 (according to the foreword, this standard was drafted according to the rules given therein)

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick Q&A