GCI TECH NOTES ©
This is part of a series of GCI Tech Notes focusing on the early development of the hazardous waste fuels programs during the early 1980s. I was hired as the facility manager for the first commercial hazardous waste operation
at a cement plant in early 1980. Many of the developments in storage, processing, testing and use of hazardous waste fuels were the result of work done at a handful of plants in the early and mid 80’s. Look for issues to
include topics on storage, lab testing methods, processing and the impact of HWF on cement product quality and production.
David Gossman, Gossman Consulting, Inc.
From the very beginning the plan for the first commercial hazardous waste fuel facility, located at the General Portland Cement plant in Paulding, Ohio and operated by Systech Corp. was that every batch of waste fuel that was burned would be tested for PCBs and a variety of volatile and semivolatile organic compounds. The challenge that I faced was that only one gas chromatograph (GC) was purchased to do the job and I made the early decision that we would do no testing “after the fact.” In other words, all testing had to be done on a truck before it was off-loaded. Testing after the load was in the tank was, and continues to be, only a way to increase liability, and certainly does not avoid it. The GC was the only piece of lab equipment that had been purchased prior to my being hired. Luckily, Systech had purchased the top end GC on the market at the time equipped with all the best options. I had an HP 5880 Level 4 instrument with dual terminals, the Basic programming language, an auto-sampler, dual FIDs, dual ECDs and a tape drive for method and data storage. Remember this was before the advent of the PC – crude integrators were the best that was available and auto-samplers were previously unheard of. This instrument was way out in front. Wow, did I have a toy!
At that time there were no capillary columns or internet to learn what the options were. The best source of information on a GC was the Supelco catalog – not a bad source even today. I set up the GC with 2mmID packed glass columns, using both a nonpolar column for the volatiles and semivolatiles (V/S) and the standard PCB column of the day. I took the extra step of packing the injection ports with glass wool to capture the nonvolatile residue from the hazardous waste fuel samples. We used soft graphite ferrules to insure good seals on the columns. Each of the programs for obtaining separation of the V/S and PCBs was about 20 minutes long and the auto-sampler would only inject one sample at a time. Add in a cool-down time and sample prep and the whole process was well over the 30 minute target for getting the testing done. What was to be done?
I hacked the computer control of the GC before anyone had invented the word “hack,” fooling the computer into starting a run on the rear injection port for the PCB run. I then aborted the run, moved the auto-sampler automatically to the front port and injected the next sample into the V/S-FID column. Then an integrator run started on the front FID detector along with a ramped temperature program. A second run was started on the rear ECD detector about 10 minutes later as the PCBs started coming off the column. We got excellent separation of both PCBs and V/S compounds and the whole system was programmed to run around the clock. Truck and tank samples were run during the day as they were prepped and standards were run overnight. The first time the HP service guys saw the system operate they about had a coronary. Later they convinced themselves that it was pretty cool that they had built a system with capabilities they did not even know about.
In those early days robotics in laboratories or anywhere else were practically unknown. It was not uncommon for an industrial or regulatory approval tour member to get the shock of his or her life when the GC would automatically inject and start the next sample analysis without anyone touching the equipment. A couple years later we got a second GC – a PE Sigma 115 with a separate computer control system (a 3600 Data System). I hacked that system as well and again had the PE people start out by telling me that what I had done could not be done – later they, too, congratulated themselves for building such a versatile system.
The HP system allowed me to write a Basic program that performed a crude pattern recognition analysis of the ECD trace for PCB congener patterns. The latter PE system allowed me to take graphical overlay software that PE had developed for IR analysis and modify it with the assistance of my wife Sue to perform overlays and pattern recognition on the PCB congener chromatograms.
Sample prep was the other major struggle at that time. S/V prep was accomplished by diluting the sample in carbon disulphide. CS2 is a nearly universal solvent and does not show up to an appreciable extent on a FID. PCBs were not so easy. The standard PCB preps of the time were based on PCBs in oil. Because of the presence of both chlorinated solvents and polar solvents the normal prep using a florisil column would not work. The solvent mix would at times create a situation where the PCBs would hang up on the prep column – and it took too long. Another factor was the use of hexane – volatile, flammable and toxic. I went another direction. We diluted the sample in isooctane and then washed the sample with concentrated sulfuric acid. The final step was to dry the sample over anhydrous sodium sulfate. Additional washings with sulfuric acid could be done if there was any indication of continued interferences. The entire prep could be done in test tubes and auto-sampler vials with relatively small amounts of sample and reagent and took less than 5 minutes.
In the end, sample prep took about 5 minutes and the run time on the GC was about 20 minutes. That allowed another 5 minutes for data interpretation and review and met our goal of a 30 minute sample turnaround.
Later developments for the S/V method included digestion of the sample with concentrated sulfuric acid and/or saturated solutions of sodium hydroxide in methanol to destroy selected organic compounds and aid in the positive identification of GC peaks. Another development was the use of both FID and TCD detection and the use of the ratio of the response factor – long before the availability of table top mass spec detectors, today’s method of choice.Please contact David Gossman at 563-652-2822 or by e-mail at email@example.com for additional information – or if you have memories to share.