GB/T 34102-2017 Determination of 2,6- di-tert-butyl-p-cresol content in jet fuel — Differential pulse voltammetry

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Card type: Test method

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

• Standard number: GB/T 34102—2017
• Chinese full title: Determination of 2,6- di-tert-butyl-p-cresol content in jet fuel — Differential pulse voltammetry
• English title: Determination of 2,6-ditertbutyl-p-cresol in jet fuels—Differential pulse voltammetry
• Replacement relationship: not provided in the available source (the word "replaces" is not seen)
• Publication/implementation: published on 2017-07-31, implemented on 2018-02-01
• Issuing bodies: General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China; Standardization Administration of China
• Drafting rules: drafted in accordance with GB/T 1.1—2009 (the source text states "ＧＢ／Ｔ１．１—２００９")
• Technical committee: National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC 280) (the source text is garbled; requires confirmation against the source standard (source-text extraction))
• Method number: not provided in the available source (the standard body does not give an internal method number)

2. Scope of application and non-applicability

• Applicable to: determination of 2,6- di-tert-butyl-p-cresol content in jet fuel.
• Determination range: jet fuel with 2,6- di-tert-butyl-p-cresol content of 8 mg/L to 31 mg/L.
• Not applicable to: the source text states this as "This standard does not apply to ...", but that sentence source-text extraction is severely garbled; the specific non-applicable objects require confirmation against the source standard (source-text extraction).
• Warning statement: the source text contains a safety reminder paragraph about "analysts should ...", source-text extraction is garbled; the specific content requires confirmation against the source standard (source-text extraction).

3. Method principle

• The source text 4 chapter (principle) states: after the sample is treated, on the composite electrode, 2,6- di-tert-butyl-p-cresol undergoes an oxidation reaction on the electrode surface, a differential pulse voltammogram is recorded, and quantification is based on the relationship between peak current (peak height) and concentration. In the source text, this paragraph source-text extraction is severely garbled; only elements such as "composite electrode", "oxidation", and "peak current" can be confirmed; the complete statement of the principle requires confirmation against the source standard (source-text extraction).
• Terms and definitions (Chapter 3):
  • 3.1 voltammetry voltammetry: an electrochemical analysis method based on the current-potential (or current-time) curve during electrolysis (the source text is garbled; requires confirmation against the source standard (source-text extraction)).
  • 3.2 differential pulse voltammetry differential pulse voltammetry: a voltammetric method in which a pulse voltage of fixed amplitude is superimposed on a DC linear sweep voltage and the difference in current before and after the pulse is measured (the source text is garbled; requires confirmation against the source standard (source-text extraction)).
  • 3.3 composite electrode composite electrode: an electrode composed of a working electrode, a reference electrode, and a counter electrode (the source text is garbled; requires confirmation against the source standard (source-text extraction)).

4. Reagents and materials (purity / preparation)

• 6.1.1 reagent (name source-text extraction garbled): purity requirement "analytical reagent"; requires confirmation against the source standard (source-text extraction).
• 6.1.2 reagent (name source-text extraction garbled): purity requirement "analytical reagent"; requires confirmation against the source standard (source-text extraction).
• 6.1.3 2,6- di-tert-butyl-p-cresol: purity requirement "analytical reagent"; requires confirmation against the source standard (source-text extraction).
• 6.1.4 solvent (name source-text extraction garbled): purity requirement "analytical reagent"; the source text has a note indicating that this reagent has an effect on ..., specifics require confirmation against the source standard (source-text extraction).
• 6.1.5 solvent + reagent mixed solution preparation: prepare in proportion, shake well, store; the source text indicates "validity period 90 days" ("９０ｖ" is suspected to be 90 days; requires confirmation against the source standard (source-text extraction)).
• 6.1.6 2,6- di-tert-butyl-p-cresol standard solution: 500 mg/L, shake well, store, validity period 90 days (requires confirmation against the source standard (source-text extraction)).
• 6.2 materials: 6.2.1, 6.2.2 names source-text extraction garbled; requires confirmation against the source standard (source-text extraction).

5. Instruments and equipment

• 5.1 electrochemical analyzer (the source text is garbled; requires confirmation against the source standard (source-text extraction)): capable of differential pulse voltammetric measurement, current measurement range 10⁻⁹ A/V; main parameters: initial potential about ±2.4 V, final potential about ±7.5 V; potential increment 0.2 mV; current increment 10 pA; current measurement accuracy as a percentage of reading ±0.2%; equipped with a three-electrode system; input impedance 1×10¹² Ω.
• 5.2 electrodes: working electrode diameter 8 mm, length 55 mm; the electrode needs to be treated by ... (the source text is garbled; requires confirmation against the source standard (source-text extraction)). Working electrode (WE) diameter 3 mm; reference electrode (AE) and counter electrode (RE) are ... electrodes, diameter 0.5 mm, length 1 cm (the source text is garbled; requires confirmation against the source standard (source-text extraction)). Table 1 is related to electrodes (the source table content source-text extraction is missing; requires confirmation against the source standard (source-text extraction)).
• 5.3 microsyringe (name source-text extraction garbled): 10 mL (as in the source text; suspected to be μL; requires confirmation against the source standard (source-text extraction)).
• 5.4 pipette/pipetting device (name source-text extraction garbled): 0.5 mL.
• 5.5 volumetric flask (name source-text extraction garbled): 50 mL.
• 5.6 graduated cylinder/measuring vessel (name source-text extraction garbled): 10 mL, with ground stopper (the source text is garbled; requires confirmation against the source standard (source-text extraction)).
• 5.7 balance: readability 0.1 mg.

6. Recommended operating conditions

• 8.2 measurement conditions: initial potential −0.5 V, final potential +0.5 V, potential increment 0.002 V, pulse amplitude 0.05 V, pulse width 0.06 s, pulse interval 0.02 s, scan rate 2.0 s (as in the source text; the unit is suspected to be mV/s; requires confirmation against the source standard (source-text extraction)), current range 1×10⁻⁵ A/V.
• 8.1 electrode pretreatment: clean the electrode, treat with 15 min to 30 min, operate according to ... (the source text is garbled; requires confirmation against the source standard (source-text extraction)), until the electrode is stable (the source text is garbled; requires confirmation against the source standard (source-text extraction)).

7. Sampling and sample preparation

• Chapter 7: sample in accordance with GB/T 4756; the sample should be stored ... (the source text is garbled; requires confirmation against the source standard (source-text extraction)).
• 9.1 Standard curve solution preparation:
  • 9.1.1 Take 10 mL volumetric flasks 4 pieces, and respectively add about 9.0 mL base fuel (the source text is garbled; requires confirmation against the source standard (source-text extraction)).
  • 9.1.2 Using a 0.5 mL pipette, respectively add 0 mL, 0.10 mL, 0.30 mL, 0.50 mL of 500 mg/L 2,6- di-tert-butyl-p-cresol standard solution, shake well, dilute to volume, to obtain standard series solutions with concentrations of 0.0 mg/L, 5.0 mg/L, 15.0 mg/L, 25.0 mg/L respectively.
• 9.2 Sample measurement:
  • 9.2.1 Take 2 mL base fuel standard series solution and mix with solvent, shake well.
  • 9.2.2 Measure according to the instrument operating conditions.
  • 9.2.3 Insert the electrode into the sample solution, record the voltammogram, measure under the conditions of 8.2, and read the 2,6- di-tert-butyl-p-cresol peak current. A typical voltammogram is shown in Figure 2 (the source figure is missing; requires confirmation against the source standard (source-text extraction)).
  • 9.2.4 Repeat 9.2.2 and 9.2.3; repeat each sample 5 times, and take the average of the peak currents.
  • 9.2.5 Repeat 9.2.1 to 9.2.4 to complete the measurement of the standard series solutions.
• Table 2 is "Differential pulse voltammetric measurement of standard series solutions" (the source table content source-text extraction is missing; requires confirmation against the source standard (source-text extraction)).

8. Analytical procedure

• See Section 7 Sampling and sample preparation, and 9.1, 9.2 in Section 9 Qualitative and quantitative determination and calculation formulas.
• For electrode pretreatment, see 8.1; for measurement conditions, see 8.2.

9. Qualitative and quantitative determination and calculation formulas

• 10.1 Standard curve: plot according to the data in Table 1 (the source text says "Table 1", suspected to be Table 2; requires confirmation against the source standard (source-text extraction)).
  • Table 1 (as in the source text) content: standard solution concentration/(mg/L): 0.0, 5.0, 15.0, 25.0; peak current/×10⁻⁷ A: 1, 2, 3, 4, 5 (the source table data source-text extraction is misaligned; requires confirmation against the source standard (source-text extraction)); average value/×10⁻⁷ A: corresponding to 0.0, 5.0, 15.0, 25.0 (as in the source text; suspected to be misaligned; requires confirmation against the source standard (source-text extraction)).
• 10.2 Standard curve regression: with standard solution concentration (c) as the abscissa and peak current (ip) as the ordinate, fit according to formula (1):
  • ip = kc + b ……………………（1）
  • Where: c—— standard solution concentration, in milligrams per liter (mg/L); ip—— peak current, ×10⁻⁷ A; k—— slope, ×10⁻⁷ A/(mg/L); b—— intercept, ×10⁻⁷ A.
  • The correlation coefficient R (95% confidence level) should be not less than 0.95.
• 10.3 Calculation of 2,6- di-tert-butyl-p-cresol content: calculate according to formula (2):
  • c₀ = (b/k) × (V/V₀) ……………………（2）
  • Where: c₀——2,6- di-tert-butyl-p-cresol content, in milligrams per liter (mg/L); V—— sample solution constant volume, in milliliters (mL), is 10 mL; V₀——sampling volume, in milliliters (mL), is 9 mL.
  • Note: The form of formula (2) is restored according to the original text source-text extraction, the meanings of symbols are subject to the original text, requires confirmation against the source standard (source-text extraction).

10. Precision

• 11.1 Repeatability: For samples with 2,6- di-tert-butyl-p-cresol content 8 mg/L～31 mg/L, measured twice by the same operator using the same instrument within a short time, the difference between the two results shall not be greater than 6%…… (unclear in the source text, requires confirmation against the source standard (source-text extraction)); repeatability is calculated according to GB/T 6683. At the 95% confidence level:
  • 11.1.1 Repeatability r = 0.58x, 0.5 mg/L (as in the original text, requires confirmation against the source standard (source-text extraction)).
  • 11.1.2 Reproducibility R = 1.08x, 0.5 mg/L (as in the original text, requires confirmation against the source standard (source-text extraction)).
• 11.2 Reproducibility: For jet fuel samples with 2,6- di-tert-butyl-p-cresol content 18 mg/L～24 mg/L, at the 95% confidence level, reproducibility R = 3.2 mg/L.

11. Report

• Chapter 12: Report the measured 2,6- di-tert-butyl-p-cresol content in the test results, in units of mg/L, with the result accurate to 0.1 mg/L.

12. Referenced Documents

• GB/T 4756 Petroleum liquids—Manual sampling (original text is "ＧＢ／Ｔ４７５６　01ÞßàNáâ·", name requires confirmation against the source standard (source-text extraction))
• GB/T 6683 Petroleum products—Determination of precision data in relation to methods of test (original text is "ＧＢ／Ｔ６６８３　0123ãä¹·Ãå梷", name requires confirmation against the source standard (source-text extraction))
• GB/T 1.1—2009 Directives for standardization—Part 1: Structure and drafting of standards (drafting basis)

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 Reference Q&A