ISO 11041:1996

Overview

ISO 11041:1996 specifies an analytical procedure for measuring particulate arsenic, arsenic compounds and arsenic trioxide vapour in workplace air. The method uses hydride generation coupled with atomic absorption spectrometry (AAS) to determine arsenic mass in air samples. It is applicable to sample masses of approximately 100 ng to 125 g of arsenic per sample (as stated in the standard) and is intended for both personal and fixed-location monitoring. The method is not suitable for arsenic present as metal arsenides. The standard includes safety warnings because arsenic and its compounds are toxic and carcinogenic.

Key Topics

• Sampling strategy
  • Collection of the inhalable fraction using cellulose ester membrane filters plus a sodium-carbonate–impregnated backup paper pad to trap arsenic trioxide vapour.
  • Designed for personal and fixed-location samplers; applicable concentration range in air depends on sampling volume and procedure.
• Sample preparation
  • Wet-ashing (nitric acid, sulfuric acid, hydrogen peroxide) to convert particulate arsenic compounds to soluble arsenate.
  • Chemical reduction of As(V) to As(III) using potassium iodide prior to hydride generation.
• Hydride generation and detection
  • Reaction of trivalent arsenic with sodium tetrahydroborate to produce arsine gas (AsH3).
  • Gas/liquid separation and transfer of arsine into a silica or quartz absorption cell mounted in an atomic absorption spectrometer.
  • Absorbance measurement at 197.2 nm or 193.7 nm using an arsenic hollow-cathode lamp or equivalent.
  • Use of continuous-flow or flow-injection hydride generation systems; absorption cell heated electrically or by an air/acetylene flame.
• Interferences and quality
  • Potential interferences from transition metals and matrix effects; analytical-curve or analyte-addition techniques recommended.
  • Reagent purity, blank controls, and recommended reagent preparations (e.g., NaBH4, KI, acids) are specified.

Applications

• Occupational exposure monitoring in industries such as metal refining, smelting, welding, mining, and chemical manufacturing.
• Use by industrial hygienists, occupational-health laboratories, environmental testing labs, and regulatory agencies for compliance testing and risk assessment.
• Monitoring of airborne arsenic species where vapour-phase arsenic trioxide and particulate arsenic are expected.

Related standards

• ISO 7708 - particle-size fractions for health-related sampling (inhalable fraction)
• EN 482 - general performance requirements for workplace atmosphere chemical agent measurement
• ISO 6955 - atomic spectroscopic vocabulary and measurement techniques
• ISO 3696 - water for analytical laboratory use

Keywords: ISO 11041, workplace air, particulate arsenic, arsenic trioxide vapour, hydride generation, atomic absorption spectrometry, arsenic monitoring, inhalable fraction, occupational exposure.