Wednesday, February 5, 2014

A Rapid and Accurate Field Method for Reduced Sulfur Compounds by GC/FPD

The session "Real Time Detection Systems I",  PO115  is scheduled to take place on June 3, 2014 from 2:00 PM to 4:30 PM.  Room numbers will be available closer to conference date. 
CURRENT TOPICS: Real-Time Detection Systems


The OSHA method for hydrogen sulfide (H2S) is complex and involves precipitation, oxidation and ion chromatographic analysis. The dimethyl sulfide and carbon disulfide are collected, desorbed with a solvent and analyzed by a gas chromatograph (GC) configured with a flame photometric detector (FPD). These methods are complex, time consuming and do not provide a fast response for the toxic sulfur compounds. A portable GC with an FPD should have sufficient sensitivity at part per billion (ppb) measurements to detect these sulfur compounds rapidly in the field without any need for sample concentration.

The Model GC312 portable gas chromatograph with an FPD was used for these tests. The PeakWorks™ four point calibration software was used to linearize the FPD sulfur (normal output is a square root response). A 30 meter thick film capillary column provides an accurate and reproducible separation for the three sulfur compounds at ppb to ppm levels in under four minutes. Samples were injected automatically using a 10 port valve. Low level samples were prepared using permeation tubes.

Results : 
Utilizing the portable GC with FPD allows for the rapid detection of sulfur compounds at ppb levels in the air. The sulfur compounds of interest include hydrogen sulfide (PEL =10 ppm), dimethyl sulfide (PEL= 10 ppm) and carbon disulfide (PEL = 20 ppm).The detection limits for the GC/FPD were found to be < 1% of the PEL.

The GC/FPD method provides a very rapid and sensitive technique for the analysis of sulfur compounds in the field in real-time. The precision of H2S for 10 samples at one tenth of the PEL was approximately 1%. Although, we have analyzed three of the problematic sulfur compounds, the same method could be applied to other compounds such as methyl mercaptan, carbonyl sulfide, etc.
AUTHORS (FIRST NAME INITIAL LAST NAME): J. N. Driscoll1, J. L. Maclachlan1
AUTHORS/INSTITUTIONS: J.N. Driscoll, J.L. Maclachlan, PID Analyzers, LLC, Sandwich, Massachusetts,  UNITED STATES;

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