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D5739-06 – Standard Test Method Technical Guide
🔬 Scope and Applicability
The D5739-06 (Reapproved 2020) standard practice utilizes gas chromatography and positive ion electron impact low resolution mass spectrometry (GC/MS) to analyze and compare petroleum oil spills with their suspected sources. This method is explicitly designed for moderately to severely degraded petroleum oils within the distillate range of diesel fuel through Bunker C residual fuel oil. It is equally applicable to crude oils whose distillation ranges fall within this spectrum. The standard notes limited applicability for kerosenes and explicitly states it is not useful for gasolines. All values are stated in SI units.
⚠️ Key Consideration for Weathering Effects: The probable source for a spill is ascertained by the examination of certain unique compound classes that demonstrate the most weathering stability. To a greater or lesser degree, chemical classes can be anticipated to chemically alter in proportion to the weathering exposure time and severity. This practice provides a guide to these expected weathering-induced analytical changes.
⚙️ Instrumentation and Key Technical Parameters
The procedure specifies a capillary column that is directly interfaced to the mass spectrometer. The system uses a low-resolution mass analyzer (quadrupole or magnetic sector) operated in the positive ion electron impact (EI) mode. Data management is handled entirely by a commercial computer-based data system for acquisition, storage, and processing.
| 🟦 Parameter | 📏 Specification |
|---|---|
| Ionization Mode | Positive Ion Electron Impact (EI) |
| Electron Energy | 70 eV (nominal) |
| GC Column | Capillary |
| Mass Analyzer | Quadrupole or Magnetic Sector |
| Data System | Computer-based (commercially available) |
📊 Significance and Source Identification Strategy
Oversight of this practice falls under ASTM Committee D19 on Water (Subcommittee D19.06). The primary value of D5739 is its utility for forensic source identification, particularly when samples are weathered. The standard recommends analyzing specific biomarker classes that resist environmental degradation. While simpler techniques such as Test Methods D3328 (GC), D3414 (Infrared), D3650 (Fluorescence), and D5037 (HPLC) may suffice for fresh spills, the GC/MS approach provides the necessary specificity for challenging casework.
| 🟦 Sample Type | 🎯 Applicability | ⚡ Weathering Condition |
|---|