Regulated workplace ketones and their interference in the PFBHA method for aldehydes

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Occupational Health

Background:

• Aldehyde air samplers can be positively interfered with by ketones.
• O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) is used for aldehyde sampling.
• Understanding ketone interference is crucial for accurate air quality assessments.

Purpose of the Study:

• To quantify ketone interference in an aldehyde dynamic air sampler.
• To evaluate the recovery rates of various ketones using the PFBHA sampling method.
• To determine optimal sampling conditions for aldehydes and ketones.

Main Methods:

• Ketone O-oxime derivatives were synthesized for quantitation.
• Wet spiking and static generation in Tedlar bags were used for recovery studies.
• Gas chromatography with mass spectrometry or electron capture detection was employed for analysis.

Main Results:

• Recoveries exceeded 75% for most tested ketones at 25°C and up to 200 ppm-hour loadings.
• Steric hindrance affected recoveries for acetophenone, 2-chloroacetophenone, and ethyl amyl ketone.
• Effective sampling of aldehydes and ketones is recommended at 10 mL/min for Threshold Limit Value (TLV) concentrations.

Conclusions:

• Ketones are significant positive interferences for PFBHA-based aldehyde air samplers.
• The PFBHA method shows good recovery for many ketones, but steric hindrance can be a factor.
• Simultaneous sampling of aldehydes and ketones at specific flow rates is feasible and recommended.