Levels Of Hydrogen Chloride Research Articles

Continuous Online Fourier Transform Infrared (FT-IR) Spectrometry Analysis of Hydrogen Chloride (HCl), Carbon Dioxide (CO2), and Water (H2O) in Nitrogen-Rich and Ethylene-Rich Streams

The prevalence of optical spectroscopy techniques being applied to the online analysis of continuous processes has increased in the past couple of decades. The ability to continuously "watch" changing stream compositions as operating conditions change has proven invaluable to pilot and world-scale manufacturing in the chemical and petrochemical industries. Presented here is an application requiring continuous monitoring of parts per million (ppm) by weight levels of hydrogen chloride (HCl), water (H2O), and carbon dioxide (CO2) in two gas-phase streams, one nitrogen-rich and one ethylene-rich. Because ethylene has strong mid-infrared (IR) absorption, building an IR method capable of quantifying HCl, H2O, and CO2 posed some challenges. A long-path (5.11m) Fourier transform infrared (FT-IR) spectrometer was used in the mid-infrared region between 1800 and 5000 cm(-1), with a 1 cm(-1) resolution and a 10 s spectral update time. Sample cell temperature and pressure were controlled and measured to minimize measurement variability. Models using a modified classical least squares method were developed and validated first in the laboratory and then using the process stream. Analytical models and process sampling conditions were adjusted to minimize interference of ethylene in the ethylene-rich stream. The predictive capabilities of the measurements were ±0.5 ppm for CO2 in either stream; ±1.1 and ±1.3 ppm for H2O in the nitrogen-rich and ethylene-rich streams, respectively; and ±1.0 and ±2.4 ppm for HCl in the nitrogen-rich and ethylene-rich streams, respectively. Continuous operation of the instrument in the process stream was demonstrated using an automated stream switching sample system set to 10 min intervals. Response time for all components of interest was sufficient to acquire representative stream composition data. This setup provides useful insight into the process for troubleshooting and optimizing plant operating conditions.

A 24-Hour Study to Investigate Persistent Chemical Exposures Associated with Clandestine Methamphetamine Laboratories

The clandestine manufacture of methamphetamine continues to be a concern across the United States. Although the exposures associated with the actual production process have been evaluated, the persistence of those exposures in a residential setting have not been investigated. This study was designed to document the contamination associated with two red phosphorous methamphetamine “cooks” conducted in a residence and the associated exposures up to 24 hours after the cook. The two cooks were conducted on the first day of the study, and exposures associated with different occupant activity levels were measured the following day. Airborne methamphetamine levels during the cook ranged from 520 μg/m3 to 760 μg/m3. On Day 2, airborne levels of methamphetamine ranged from 70 μg/m3 to 210 μg/m3 and increased with moderate to high activity levels within the residence. The majority of the methamphetamine measured during both days had a particle size of less than 1 μm, suggesting that the methamphetamine is formed as a condensation aerosol and is readily resuspended from contaminated surfaces. Significant methamphetamine contamination was found in the carpeting and likely was associated with the elevated levels of methamphetamine during activity. Levels of hydrogen chloride and iodine were also detected on Day 2 of the project although at very low levels. The study concluded that exposures may still present a significant inhalation exposure well after the actual cook.

Real time air monitoring of hydrogen chloride and chlorine gas during a chemical fire

On 9 August 2000 a fire started at a facility that manufactures pool chemicals in Guelph, Ontario. A mobile trace atmospheric gas analyzer (TAGA) unit was summoned to provide on-site air monitoring operated by the Ontario Ministry of the Environment (OMOE). The responsibility of the TAGA unit was to monitor in real time the airborne contaminants released through the combustion of pool chemicals. This was accomplished by using an atmospheric pressure chemical ionization (APCI) source with the newest TAGA (model IIe): a triple quadrupole mass spectrometer which allows for the direct sampling and real time analysis of air for a wide range of toxics at low parts-per-billion (ppb) levels. The ionization mechanism under negative APCI conditions is dominated by charge transfer reactions, yielding parent ions which are selected in Q1, dissociated in Q2 and the resultant daughter ions are identified in Q3. By monitoring specific parent/daughter (P/D) ion pairs, the TAGA IIe was able to simultaneously measure, in real time, levels of hydrogen chloride (HCl) and chlorine (Cl 2) present in the air. The response of the TAGA IIe was characterized by multi-point calibration curves which were linear up to 250 μg/m 3 for HCl and up to 600 μg/m 3 for Cl 2. The average detection limit (DL) for this application was 0.50 μg/m 3 for both HCl and Cl 2. On-site measurements of HCl and Cl 2 were made at several locations upwind and downwind of the fire site over a period of 3 days. The data collected by the TAGA unit was used by the local officials for a real time assessment of the airborne levels of HCl and Cl 2.