SH/T 0656-1998 Standard test methods for instrumental determination of carbon, hydrogen and nitrogen in petroleum products and lubricants

Summary page. This page is a compiled excerpt/summary of the standard — it is not the full standard text and does not replace it. Verify every value against the official standard and the product certificate before use.

Evidence note: unofficial method study card for the historical 1998 edition; not the full text of the standard and not an operating procedure. Technical review is pending, and the current status and product applicability are unconfirmed. The doubts in the original regarding the nitrogen boundary, the identity of the compounds and the air unit are retained.

1. Method identity and reading boundaries: Original PDF pages 1-4 (cover, copyright, foreword, clause 1 of the body). This card is compiled from the scanned original SH/T 0656-1998, Standard test methods for instrumental determination of carbon, hydrogen, and nitrogen in petroleum products and lubricants. Issued 1998-06-23, implemented 1998-12-01. The queue and file name carry the NB/SH/T prefix, while both the original cover and body read SH/T; the identity of the original is used here, and the conditions of the 2017 edition are not written into the 1998 edition. The English title is Standard test methods for instrumental determination of carbon, hydrogen, and nitrogen in petroleum products and lubricants. The foreword records the historical equivalent adoption of ASTM D5291-96 and the change of its nitrogen range to 0.1% to 2% (m/m); this historical record is not a conclusion of present equivalence or current status. The original has methods A, B and C and does not have method D of the 2017 card. The current version status and applicability are unconfirmed.

2. Scope and limitations: PDF page 4, clause 1. The methods determine total carbon, total hydrogen and total nitrogen in petroleum products and lubricants; the original examples of samples are crude oil, fuel oil, additives and residues. Clause 1.2 gives the mass fraction ranges as carbon 75% to 87%, hydrogen 9% to 16% and nitrogen 0.1% to 2%. Clause 1.3 excludes light materials with nitrogen below 0.75%, listing gasoline, jet fuel, naphtha, diesel and chemical solvents; clause 1.4 separately excludes volatile materials. "Below 0.75%" must not be rewritten as a blanket exclusion for all samples, and the 0.1% lower limit alone does not promise applicability to light low-nitrogen samples. The results are mass percentage contents. The nitrogen range of the original differs from the 0.75% to 2.5% of the precision table; each is retained, and the upper precision limit is not substituted for the method range. The hazardous materials mentioned and the high-temperature gas operation must follow the controlled standard, the instrument instructions and the safety rules; this study card is not an operating procedure.

3. Principle and the differences between A, B and C: PDF pages 4-5, clauses 3-4. The sample is burned in pure oxygen at high temperature to form CO2, water vapour and nitrogen/nitrogen oxides, which are freed from interferences and determined separately. The concentration is obtained from the detector response, the response per unit mass established by calibration, and the sample mass; the instrument provides automatic calculation. Method A: sulphur oxides are removed, hot copper removes oxygen and reduces nitrogen oxides; nitrogen is detected by thermal conductivity, and carbon and hydrogen are detected as CO2 and water by infrared. Method B: the treated gases are homogenized in a mixing chamber of known volume, temperature and pressure, then separated on a heated chromatographic column. Method C: after treatment with hot copper, the column separates nitrogen, CO2 and water vapour, which are detected by thermal conductivity. The original significance and uses concern process, depth of processing, yield, additives and the hydrogen-carbon relationship. This card provides no conformity judgement or product performance claim.

4. Apparatus and consumables: PDF pages 5-6, clause 5. The elemental analysis system must achieve complete conversion, removal of interferences, a suitable response range and concentration output; auxiliary components may be used. The analytical balance has a readability of 0.00001 g, and a syringe or small tube is used for transfer; the balance readability must not be confused with the sample mass requirements of the individual methods. The materials include large and small tin capsules, ceramic crucibles, copper capsules, tin plugs, tin boats, copper inserts, aluminium and nickel capsules, combustion tubes, absorption tubes and reduction tubes. Oxygen purity is ≥ 99.998% and helium ≥ 99.995%; air, nitrogen or argon may be used for pneumatic valves, and CO2 is also listed. Specific products, packaging and certificates are not confirmed in this item, and no association is added.

5. Reagents and calibration substances: PDF pages 6-8, clause 6 and Table 1. The original requires chromatographic-grade reagents; other grades must ensure the accuracy of the determination. Acetanilide or another suitable pure compound is used for calibration; the table below is a factual rearrangement of the mass percentages of original Table 1, blank cells remain "—" and are not zero. The carbon value in the fourth row is 51.79 in the scan, misread by OCR as 31.79, and has been checked against the source image. Some molecular formulae and compound names in the table carry transcription/printing doubts; this page does not use unverified formulae as procurement identities and does not rename them from chemical knowledge on its own initiative; the percentages still require technical review and cannot replace a batch certificate. Method A lists NaOH-coated silica, quartz wool, magnesium perchlorate, copper granules, CaO-coated material, a nitrogen catalyst and MgO for liquid samples. Method B additionally lists EA1000, silver tungstate-coated MgO, silver vanadate, silver gauze, CuO, tungsten oxide, cobalt oxide, aluminium oxide and platinum gauze. Method C lists chromium oxide, cobalt oxide-coated silver, reduced copper, 3A molecular sieve (1.6 mm) and red diatomaceous earth Chromosorb; the choice follows the instrument instructions, and the reagents of the three methods are not considered interchangeable. | Compound in the original table | Carbon % (m/m) | Hydrogen % (m/m) | Nitrogen % (m/m) | | --- | --- | --- | --- | | Acetanilide | 71.09 | 6.71 | 10.36 | | Atropine | 70.56 | 8.01 | 4.84 | | Benzoic acid | 68.84 | 4.95 | — | | Cyclohexanone-2,4-dinitrodiphenylhydrazone (name as in the original table) | 51.79 | 5.07 | 20.14 | | Cystine (letterform of the name in the original table [to be verified]) | 29.99 | 5.03 | 11.66 | | Biphenyl | 93.46 | 6.54 | — | | EDTA | 41.10 | 5.52 | 9.59 | | Imidazole | 52.92 | 5.92 | 41.15 | | Nicotinic acid | 58.53 | 4.09 | 11.38 | | Stearic acid | 75.99 | 12.76 | — | | Succinamide | 41.37 | 6.94 | 24.13 | | Sucrose | 42.10 | 4.48 | — | | Sulfanilamide (name as in the original table) | 41.84 | 4.68 | 16.27 | | Triethanolamine | 48.30 | 10.13 | 9.39 |

6. Typical operating conditions of the original edition: PDF pages 9-10, clause 9. These values are the typical conditions of this edition; actual execution follows the instrument instructions and the controlled method. Method A: main/auxiliary combustion zone 950 °C, catalyst 750 °C, column oven 53 °C; oxygen and helium pressures both 275.8 kPa. Helium 400 cm³/min (normal) and 70 cm³/min (purge), oxygen 7 dm³/min, air 6 dm³/min. Method B: combustion 975 °C, reduction 640 °C, detector 80-84 °C; helium 137.9 kPa, oxygen 110.3 kPa, air/nitrogen/argon 413.7 kPa. Method C: combustion 1020 °C, reduction 650 °C, detection oven 60-100 °C, filament 190 °C; cycle 420 s, autosampler start 20 s and return stop 70 s, oxygen addition 70 s, integration window delay 2 s. Oxygen line pressure 100 kPa/20 cm³/min, helium 200 kPa (reference 40, measure 80, purge 60 cm³/min). The air line pressure is 500 kPa, but the original "flow rate" column prints 3.5 kg/cm², which is a pressure unit; it is retained as written [to be verified] and must not be guessed into a flow rate or used as a set point.

7. Sampling and sample preparation: PDF page 7, clause 7. The laboratory sample is a representative portion taken according to GB/T 4756 or SH/T 0229; a viscous sample is heated until it flows and shaken for 5 s, then transferred with a clean syringe or small tube into a sealed capsule. The original gives no heating temperature, and this card adds none.

8. Tube preparation and replacement: PDF pages 8-9, clause 8. Preparation and calibration follow the instrument instructions; quartz/glass parts are degreased with soap, water and acetone, and gloves are worn to avoid fingerprints. The combustion/absorption tubes are replaced in the original after 50 to 300 runs; the exact interval follows the instrument instructions, and 300 is not taken as a fixed service life. Method A: the combustion tube lists, in the inlet/outlet direction, 5 cm and 3.1 cm quartz wool, 6.3 cm combustion agent, 11.9 cm quartz wool and a ceramic crucible; the reduction tube has, above the copper insert, 8.8 cm of nitrogen catalyst and 13.8 cm of copper granules. The assembly direction and components must be checked against the original figure and text, not on the dimension table alone. Method B: EA1000 and silver tungstate-coated MgO are preheated at 900 °C for 10 to 30 min; from the combustion tube outlet the order is 2.5 cm quartz wool, 5 cm EA1000, a thin quartz layer, 5 cm silver tungstate-coated MgO, a thin layer, 2.5 cm silver vanadate, a thin layer and silver gauze, with a gap of about 1.2 cm before the quartz wool. The reduction tube has a 23.8 cm copper column, a thin layer, 1.2 cm CuO, a thin layer and the copper insert. Method C: combustion tube 2 mm quartz wool, 50 mm cobalt oxide-coated silver, 10 mm quartz wool, 120 mm chromium oxide, 10 mm quartz wool; reduction tube 5 mm quartz wool/reduced copper/10 mm quartz wool (the original gives no copper length). The dehydration tube is 10 mm quartz wool/3A or magnesium perchlorate/10 mm quartz wool; the CO2 removal tube is 10 mm quartz wool/50 mm magnesium perchlorate/130 mm NaOH-coated silica/50 mm magnesium perchlorate/10 mm quartz wool. This is only for checking against the original; it is not a tube-loading drawing or an installation instruction.

9. Analysis and calibration checks: PDF pages 9-10, clause 9. Method A uses about 50 to 200 mg of sample weighed to 1 mg; solids in tin capsules, liquids in copper capsules sealed with MgO and a tin plug. First 2 to 4 blank capsules, then 5 standard samples; the original requires blanks within ±10% and standard samples within ±1% of the theoretical value, and after establishing a single-point curve the standard is re-measured (reproducibility or difference < 1%) before the samples are run; the basis of the blank percentage in the original is not further explained and must not be supplemented by assumption. Method B uses about 2 to 4 mg weighed to 0.02 mg, flattened, folded and then pressed flat and folded again; 2 to 4 blanks are run interspersed with the samples, with adjustment of oxygen quantity/combustion time. The standard response factor K is the count divided by the mass of the corresponding element in the standard, and must lie within the range of the instrument instructions. Method C uses about 5 mg weighed to 0.02 mg in a tin capsule; a liquid sample additionally receives about 30 mg of red diatomaceous earth. An unweighed sample is first run to determine the retention time, then 1 to 2 blanks, then 2 to 3 standards to obtain K or 3 to 6 standards for linear regression; standards are inserted during the run for checking and updating, generally 1 standard per 10 samples.

10. Calculation and units: PDF page 10, equation (1) of clause 10: A = (B × E × F) / (C × D). A is the mass percentage content of the element in the sample; B and C are the blank-corrected responses of the sample and the standard respectively, D and E the masses of the sample and the standard (g), and F the mass percentage content of the element in the standard. The last term of the numerator is clearly F, misread by OCR as D; D must not be allowed to cancel. The original instrument system provides the calibration curve automatically. Only the original equation is recorded; the calculation by any instrument software, the blank subtraction or the applicability to a product certificate is not confirmed, and technical review is pending.

11. Precision and bias: PDF pages 10-11, clause 12. Twenty-six laboratories and 14 petroleum-based samples gave the common precision of methods A/B/C; x is the mean of two results and each column is a mass percentage. The nitrogen precision range of 0.75% to 2.5% and the 0.1% to 2% of clause 1.2 are listed separately and are not unified. No acceptable petroleum-based reference material was available to determine the operating bias, so the bias of the original cannot be determined. This does not mean the measurement has no bias. | Element | Precision range % (m/m) | Repeatability | Reproducibility | | --- | --- | --- | --- | | Carbon | 75-87 | 0.0072(x+48.48) | 0.018(x+48.48) | | Hydrogen | 9-16 | 0.1162(x^0.5) | 0.2314(x^0.5) | | Nitrogen | 0.75-2.5 | 0.1670 | 0.4456 |

12. Reporting and referenced documents: PDF pages 4 and 10, clauses 2 and 11. Carbon, hydrogen and nitrogen are reported as mass percentage contents. The references are GB/T 4756, Petroleum liquids — Manual sampling, and SH/T 0229, Sampling of solid and semi-solid petroleum products; the original gives no years for these references and this card does not guess the corresponding versions. The wording in clause 2 of the original about references being "current" is part of the 1998 text and is not taken as proof of validity in 2026.

13. Sources and items to be verified: Page-by-page visual check of the 11-page original held; item 4 of the queue for 2026-10-06. The original covers the cover, copyright, foreword and printed body pages 1-8, ending at 12.2 bias; the 2017 edition has not been used to fill in method D, and the original and its OCR are read-only. This page is an original project method study compilation and table of technical facts, not the full text of the standard, and no download of the original scan is offered. [To be verified]: the letterforms of the compound names/formulae and the identity of the original table, the basis of the blank percentage, the pressure unit of the air "flow rate", the respective boundaries of the nitrogen range and the precision range, the instrument configuration and collation against the controlled copy; the current status, final applicability and independent technical review are all incomplete.

14. Quick questions and answers: Compiled from the original clauses cited above. How many methods does the 1998 edition have? Three, A/B/C; method D of the 2017 edition is not imported. Does it apply to gasoline? The original excludes light low-nitrogen and volatile materials; the 0.1% lower nitrogen limit alone is not sufficient. Can the 2.5% upper precision limit be treated as the determination range? No; the method range and the statistical precision range are different. Can the tubes be loaded from the table, or the air 3.5 kg/cm² be treated as a flow rate? No; the original, the controlled method and the instrument instructions must be checked. Can a certificate or suitability for a product be demonstrated? No; this card adds no product relationship. Public consumables note: this item confirms no product applicability relationship; please check the product certificate and the controlled method before selecting consumables.

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