Arsenic in Petroleum Naphthas

UOP Method 296-82: Arsenic in Petroleum Naphthas

For engineers and chemists in the oil and gas and petrochemical sectors, precise analytical methods are paramount for ensuring product quality, meeting regulatory standards, and safeguarding operational integrity. UOP Method 296-82 stands as an authoritative and essential guide for accurately determining arsenic concentrations in petroleum naphthas, a critical task that impacts downstream processing and final product specifications.

What is UOP Method 296-82?

UOP Method 296-82, developed by UOP LLC, is a proven, industry-leading standard for the quantitative determination of total arsenic in petroleum naphtha streams. Its primary purpose is to provide a reliable and reproducible laboratory procedure for measuring arsenic content down to parts per billion (ppb) levels, ensuring that critical quality parameters are met.

Scope & Purpose

This comprehensive method governs the analytical process for quantifying arsenic in petroleum naphthas. It details the necessary laboratory apparatus, reagents, and step-by-step procedures, from sample extraction and digestion to the final arsine generation and detection. The scope is specifically focused on total arsenic in naphtha matrices; it does not cover other hydrocarbon types or speciation of arsenic compounds.

Who Must Comply?

• • Primary audience: Laboratory Technicians, Analytical Chemists, Quality Control Analysts, and Process Engineers involved in petroleum product testing and quality assurance.
• • Industries affected: Oil and Gas (refining), Petrochemical Manufacturing, and Chemical Production.
• • Compliance nature: While not a regulatory mandate in itself, compliance is often required by contractual specifications, internal quality control programs, and as a basis for meeting broader environmental or product purity regulations. It is a recommended best practice for consistent and reliable results.
• • Enforcement: Compliance is typically verified through internal quality assurance audits, customer audits, and by demonstrating adherence to UOP standards in quality control reports.

Key Requirements Overview

The standard outlines several critical requirements for accurate arsenic determination:

• • Sample Handling: Professionals must ensure proper sample collection and storage in amber glass bottles to prevent arsenic loss to container walls, with analysis conducted promptly.
• • Extraction Efficiency: The method requires a two-step extraction process using specific chemical solutions (sodium hypochlorite and sulfuric acid) to efficiently remove arsenic from the naphtha matrix.
• • Digestion and Purification: A crucial step involves the digestion of extracted samples with nitric acid and hydrogen peroxide to destroy organic interferences, followed by purification of the generated arsine gas to remove detrimental byproducts like hydrogen sulfide.
• • Arsine Generation & Detection: The procedure mandates the use of a Gutzeit apparatus or equivalent for controlled arsine gas generation with zinc and acid, and the precise measurement of color development on mercuric bromide-impregnated paper strips.
• • Calibration and Control: Rigorous adherence to preparing and running standards under identical conditions as the sample is essential for accurate quantification by comparing color strip lengths.

Related Standards & References

UOP Method 296-82 often complements other analytical standards. While not explicitly detailed in the provided extract, common complementary standards in this domain include those from ASTM International (e.g., for general petroleum product testing or specific trace metal analyses) and potentially ISO standards for international applications. These standards collectively ensure a robust framework for chemical analysis