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Formate, hydrogen gas, and nitrous oxide

Greetings from San Diego! I heard some great new safety training ideas in yesterday’s CHAS session on “It’s not all about PowerPoint,” and I’ll share them next week when I’ve got more time to write. In the meantime, today’s issue of C&EN includes a follow-up letter on the NO/methanol explosion reported from Merck in January:

A safety letter from Merck & Co. chemists titled “Nitric Oxide at High Pressure” (C&EN, Jan. 30, page 6) described two explosions during depressurization of a reaction between NO and methanol under basic conditions. The products in a model system with sodium methoxide were described as nitrous oxide and formic acid, presumably as sodium formate. A potential danger in this system should be pointed out: Sodium formate undergoes thermal decomposition to give hydrogen gas (J. Am. Chem. Soc., DOI: 10.1021/ja02245a004), which explodes spontaneously in the presence of nitrous oxide above critical limits (J. Am. Chem. Soc., DOI: 10.1021/ja01179a036), even in the absence of a catalyst or source of ignition.

The presence of hydrogen and nitrous oxide above a reaction mixture was undoubtedly the cause of an explosion and fire in my laboratory in 1981 during workup of a reaction between sodium and nitric oxide. The major product of the reaction is cis-sodium hyponitrite, which decomposes immediately in water to form sodium hydroxide and nitrous oxide. The employee, a biology major who was badly burned, had carried out the reaction a number of times without incident. This time he tried twice and failed to disperse about 30 g of sodium in toluene and, without consulting me, decided to continue the reaction. The explosion occurred as he was attempting to destroy the unreacted sodium, a lump too large to remove from the flask, by dropwise addition of water.

Most of the sodium had reacted at the time of the explosion, and there was no indication of mechanical failure. At the time, I was unaware of the extreme incompatibility of the two gases, and the accident was extremely puzzling. The reaction mixture was close to room temperature and was stirred rapidly while the headspace was flushed with a stream of nitrogen. When I arrived at the laboratory a few minutes after the accident, nitrogen was still flowing from the burned-off end of the plastic tubing.

Since that time, I noticed a reference to the “hydrogen explosion” in the ancient chemical literature as a way to identify nitrous oxide.

By David Mendenhall
Elmsford, N.Y.

Letters on the felony charges in the Sangji case

We have a couple of letters in this week’s issue regarding the felony charges against the University of California and UCLA chemistry professor Patrick Harran for health and safety violations that led to the death of researcher Sheharbano (Sheri) Sangji.

The letters respond specifically to a January 16 editorial on the charges and a possible prison sentence for Harran. C&EN Editor-in-Chief Rudy Baum wrote:

That UC and Harran should face no sanctions given the facts that are known is unacceptable. As Kemsley said to me in a conversation about the case, the only people who think of a 23-year-old as experienced are 21- and 22-year-olds. Sangji was clearly unprepared to conduct the experiment that killed her. Other people in Harran’s lab who were there at the time of the accident were just as ignorant of basic safety procedures.

That said, sending Harran to prison for what are all-too-common safety lapses in academic labs would be overly harsh and almost certainly counterproductive. We need to change the safety culture in academic labs, not shut them down. If Harran is found guilty of the charges against him, a hefty dose of community service—maybe teaching lab courses and lab safety in Los Angeles high schools—would be a much more appropriate penalty to impose on him.

C&EN readers responded:

Rudy Baum suggested that “teaching lab courses and lab safety in Los Angeles high schools” would be appropriate community service for a person found guilty in a UCLA laboratory accident (C&EN, Jan. 16, page 3). I agree.

A significant national issue involves educational preparation of science students before they enter college or university. Every student needs hands-on experience in laboratory techniques and laboratory safety in science courses taught by qualified teachers in high school and earlier. Moreover, students need that laboratory instruction in modern facilities, with safety equipment that meets current codes and regulations.

I learned experimental chemistry in a small rural town. My father, who spent 48 years as a science teacher, taught the high school chemistry course. Each of my 40 years as a college chemistry teacher involved extensive laboratory instruction, with an emphasis on educating students to work safely with hazardous chemicals. Appreciation of chemical safety is learned incrementally; it’s best when that learning begins at an early age and is accompanied with knowledgeable mentoring.

Progress in chemical safety will be painfully slow at research levels until feeder schools—especially high schools—are well staffed with credentialed science teachers who are provided appropriate support.

By George Fleck
Northampton, Mass.

Being the left-leaning, environmentally minded ex-chemist that I am, I generally agree with Baum’s editorials. However, as a California prosecutor I was surprised to read his take on the punishment that UCLA chemistry professor Patrick Harran should receive for his part in the death of Sheharbano Sangji. A young woman, who received no safety training and wasn’t even wearing a lab coat, died while working unsupervised with a pyrophoric liquid, and Harran should face only community service because safety lapses in academic labs are “all-too-common”? Imagine if we applied that logic to DUIs and other “all-too-common” offenses that result in injury and death.

This letter expresses my opinion only and not that of my employer.

By Dije Ndreu
Monterey, Calif.

Arraignment postponed again for UCLA, Harran in Sheri Sangji case

The University of California, Los Angeles, and chemistry professor Patrick Harran were scheduled to be arraigned today for felony violations of California labor laws, but the case has been delayed again, reports C&EN SCENE editor Michael Torrice. Arraignment is now scheduled for April 11. The case arose from a 2008 fire in Harran’s lab that led to the death of researcher Sheharbano (Sheri) Sangji.

Torrice says that the courtroom proceeding was much the same as last month: Attorneys spoke privately with the judge, then stepped back to publicly reschedule the arraignment.

UCLA, Harran arraignment in Sheri Sangji case delayed (again)

Arraignment of the University of California, Los Angeles, and chemistry professor Patrick Harran for felony violations of California labor laws has been postponed, reports C&EN SCENE editor Michael Torrice. The charges stem from the death of researcher Sheharbano (Sheri) Sangji three years ago after a fire in Harran’s lab.

Torrice was in the courtroom this morning and says that defense attorneys spoke with the judge in private, then requested that the arraignment be delayed. While Harran’s arraignment was originally scheduled for today, UCLA’s was already postponed once, from Jan. 12. The new date for both defendants is March 7.

ETA: The Los Angeles Times has a photo taken in the courtroom.

(Not familiar with C&EN’s SCENEs? They’re news streams focused on analytical, biological, environmental, and materials chemistry.)

“So I had a flaming flask in my hands…” courtesy of potassium hydride

Milkshake of Org Prep Daily this week reported on a fire in his lab from a potassium hydride reaction:

I had a rather bad fire last Friday. I was washing a large jacketed glass reaction vessel used for polymer scale-ups, after pouring the reaction mixture out, and a tiny particle of potassium hydride (from this poorly quenched reaction) that was adhering to the bottom of the reaction flask ignited just as I was giving the flask a proper acetone rinse. So I had a flaming flask in my hands + burning hands + flaming sink in front + a whole bunch of wash bottles ablaze next to me (plastic wash bottles peeing their burning solvents around…) A colleague promptly put the fire out with a mid-sized CO2 fire extinguisher before the flames spread any further. There was no damage to the lab, my fingers or the reaction mixture but it was pretty scary situation – considering how fires in organic labs can get out of control so fast.

There’s more at his post, where he includes a general heads up to the chemistry community:

Since K-alkoxides have significant reactivity advantages over Na and Li alkoxides in alkylation reactions[2], and since the easy-to-handle KH formulation in paraffin wax is now commercially available, it is likely that KH will get used increasingly more in place of NaH. Despite its innocuous appearance KH is less tame than NaH; having unreacted KH excess present in the reaction mix makes it prone to suddenly burst into flames during the workup if the reaction is not quenched with care.

Derek Lowe weighed in on the incident at In The Pipeline: “If you’re going to use KH, don’t let your guard down.”

Using nitric oxide at high pressure

We have a safety letter regarding nitric oxide reactions in this week’s issue of C&EN:

Chemists at Merck & Co. were performing experiments using nitric oxide at high pressure (10–20 bar) when two instances of an explosion occurred during rapid depressurization of the NO headspace from a 500-mL closed reactor system. No injuries occurred, and damage was contained to the barricaded cell area. Both before and in between these events, NO had been used successfully about 100 times. Each explosion occurred after completion of the reaction, while venting through three-eighths- or one-quarter-inch i.d. Teflon-lined steel-braided tubing to atmospheric pressure.

Static electricity was suspected as the ignition source that, in conjunction with the presence of an oxidant (NO) and fuel (CH3OH), would lead to combustion. To confirm this hypothesis, an investigation was conducted. Preliminary results are communicated here.

The reaction system consisted of NO in conjunction with methanol under basic conditions. A literature search didn’t point to any existing cautionary notes about this reaction. Experimental ignition testing of NO systems was conducted by Fauske & Associates, which showed no combustion unless ignition energy greater than 3 J was used. This exceeds the energy typical of a static discharge, so it does not fully explain the observed combustion.

Further analysis of the reaction headspace using gas chromatography/mass spectrometry revealed that N2O was formed over time from a simple model system of NO + sodium methoxide + methanol. The conversion of NO to N2O and concomitant oxidation of methanol to formic acid proceeds to 50% in about six hours. Testing showed the energy needed to ignite the headspace of methanol under 1 bar of 50/50 NO/N2O is less than 3 mJ, several orders of magnitude lower than for similar systems without N2O.

On the basis of these results, the likely cause of the explosions is the combination of (a) formation of N2O gas and (b) generation of static potential caused by the rapid flow of gas and condensing methanol through the Teflon-lined tubing during rapid depressurization (while venting), which leads to sparking of sufficient energy to cause the combustible vapor to ignite.

We wanted to alert the chemical process industry to risks associated with this particular procedure. Anyone contemplating use of this chemistry should thoroughly evaluate its safety.

Daniel Muzzio, Ephraim Bassan, Erik Dienemann, Mark Weisel, Cameron Cowden, Scott Hoerrner, William Olsen, Michael Man-Chu Lo, Amjad Ali
Branchburg, N.J.

#SheriSangji case: The limits of oral transfer of knowledge

As others have also reported, a second Cal/OSHA report has surfaced on the circumstances surrounding the death of University of California, Los Angeles, researcher Sheharbano (Sheri) Sangji from a laboratory fire. The first report, which I covered extensively back in 2009, was the one that led to civil sanctions against UCLA. As is standard in a California workplace fatality, once the civil case was completed, it was turned over to Cal/OSHA’s Bureau of Investigations (BOI) to determine whether it might warrant criminal prosecution. The newly-available report is the one that the BOI sent to the Los Angeles County District Attorney, who filed criminal charges against UCLA and chemistry professor Patrick Harran.

The report paints a pretty damning picture of overall UCLA safety culture at the time of the incident. To quote from the report’s conclusions (report page 90):

Based upon the investigation, it is apparent that the laboratory safety policies and practices utilized by UCLA prior to Victim Sangji’s death, were so defective as to render the University’s required Chemical Hygiene Plan and Injury and Illness Prevention Program essentially non-existent. The lack of adequate lab safety training and documentation, lack of effective hazard communication practices, and repeated failure to correct persistent and repeated safety violations within University labs, were all causal deficiencies that led to a systemic breakdown of overall laboratory safety practices at UCLA.

Much of the report just gives added detail to what was already known about the case or documents conventional wisdom about poor lab safety culture in academia. In one interview, postdoctoral researcher Paul Hurley noted that lab coats were seen as optional rather than required in every academic lab he’d worked in. “That’s how my experience has been pretty much everywhere I’ve been, apart from my current job actually,” the report quotes Hurley. Where does he work now? In industry.

Credit: UCLA

The report does reveal, however, a bit more of how Sangji was supervised and trained. To recap the incident, Sangji was using a syringe to transfer about 53 mL of tert-butyllithium (tBuLi), a pyrophoric substance that ignites spontaneously in air, when the barrel came out of the syringe. The chemical splashed on Sangji, who was wearing neither a regular nor a flame-resistant lab coat, and set her clothes on fire. She was burned on more than 40% of her body and died of her injuries.

The report confirms that Sangji did not handle pyrophoric reagents as an undergraduate or during a few months of work at Norac Pharma. At UCLA, Sangji worked in Harran’s lab. Harran told the Cal/OSHA investigator that he observed Sangji do an initial experiment to gauge her experience and competency (the summary of Harran’s interview starts on page 67). Assuming that the experiment Harran referred to is the first entry in Sangji’s lab notebook–the second is her first tBuLi reaction–the procedure involved working in a glove bag and syringing no more than a few milliliters of air-sensitive, non-pyrophoric material. Although some of the fundamental techniques might have been the same, I think many people would argue that in scale and hazard that first reaction was a far cry from Sangji’s tBuLi experiments (synthetic chemists: feel free to weigh in on this point in the comments).

As for handling tBuLi, Harran reportedly told Sangji to ask Hurley for help. Hurley told the Cal/OSHA investigator that he didn’t follow standard operating procedures or other written protocols; rather, he was trained and in turn trained others by word of mouth (the summary of Hurley’s interview starts on page 59). Hurley also couldn’t recall the specifics of his interactions with Sangji. The way Hurley described handling pyrophoric reagents, however, echos some of what contributed to the lab fire that ultimately killed Sangji:

  • Hurley said in the interview that “most people…more often than not did not clamp the bottle” and instead held it with one hand while syringing with the other. Aldrich recommends (pdf) clamping the bottle, which leaves both hands free to manipulate the syringe. (Sangji compounded this by using a 60-mL syringe with a short needle, so would have had to tip the bottle up to get the needle into the liquid while trying to handle a large syringe with one hand.)
  • Hurley said that he always used plastic syringes. Aldrich does not specifically prohibit using plastic syringes, but it does recommend drying syringes in an oven, which effectively means that glass must be used. (Sangji used a plastic syringe. Another postdoc in the lab, Hui Ding, commented that plastic syringes can swell, making them difficult to operate.)
  • Hurley said that he would use a syringe size as close to the reagent volume as possible. Aldrich recommends using a syringe at least twice the volume of the reagent volume, precisely to guard against taking the plunger out to the end of the barrel. (Sangji used a 60-mL syringe for 50 mL or more of material. Ding knew about the twice-the-volume rule.)
  • Hurley said that he would physically pull on the plunger to pull up the reagent. Aldrich recommends using low-pressure, inert gas to push the material into the plunger rather than risk pulling too hard on the plunger and drawing in air. (It’s not clear which approach Sangji used. When Harran was interviewed by Cal/OSHA investigators in the civil investigation, he also said that he’d pull on the syringe. Aldrich scientist Mark Potyen has previously told me that plastic syringe plungers can’t be pushed up by low-pressure gas.)

(What’s not addressed in the report is the issue of transferring material by syringe versus a double-tipped needle, or cannula. On the day of the incident, Sangji was supposed to transfer a total of about 160 mL. For that amount, a cannula is the accepted practice rather than multiple smaller transfers. It’s not clear that anyone ever said that to Sangji. Certainly no one told her to read the Aldrich protocol.)

The Hurley interview clearly illustrates the limit of oral transfer of knowledge. As in a game of telephone, what gets passed on can change over time. Written protocols help guard against that. And making lab workers (re-)write protocols that faculty then review helps to ensure that everyone does, in fact, know what they’re supposed to do.

Other points of note: Sangji started in the lab in October, 2008. Hurley left the lab in November. According to the report, on the day of the incident in December, Harran knew that Sangji was planning to scale up the tBuLi reaction but told the investigator that he didn’t know by how much. Harran seems never to have discussed the hazards or use of tBuLi with Sangji.

Around the web today, I’ve seen a couple of people ask why the DA didn’t file charges against Hurley. My guess is that it comes down to the legal statute, California Labor Code Section 6425, which specifies “Any employer and any employee having direction, management, control, or custody of … any other employee.” Harran clearly fits that description–he hired Sangji, directed her work, and was ultimately in charge of his lab. I don’t see that it applies to Hurley, who was not explicitly assigned to supervise Sangji’s work and who was gone from UCLA by the time of the incident.

Last but not least, one caveat about the report: It is basically a summary of what the investigator found. The full package appears to involve five binders of information, which I do not have (nor, as far as I know, does anyone else outside of Cal/OSHA or the DA’s office). When reading the report, I think it’s important to remember that you’re not getting the full interview transcripts and we don’t know what the investigator may have left out. (I tried to get everything back in 2010, but was told that because the report was part of an ongoing criminal investigation, it was exempt from disclosure under California’s Public Records Act [pdf summary].)

Friday chemical safety round-up

Chemical health and safety news from the past week:

Things we’re following

  • The case against UCLA and Patrick Harran in Sheharbano (Sheri) Sangji’s death: UCLA was scheduled to be arraigned on Thursday, but the case was continued to Feb. 2, the same day as Harran’s arraignment. Chemistry World weighed in this week with What does it take to improve lab safety? and Will Sheri Sangji’s death change safety culture? (related Reddit discussion) while ChemBark discussed making safety training a part of group meetings and ScienceGeist tackled teaching safety to undergrads (related: teaching safety and safety teams)
  • Another azide explosion and student injured at the University of Florida: On Monday, C&EN published a safety letter from UF chemistry professor Alan Katritzky on avoiding acid work-up of benzotriazole-1-sulfonyl azide. The concern is that residual sodium azide may convert to hydrazoic acid, which was the likely culprit when a flask exploded and injured a student last fall. On Wednesday, there was another explosion in Katritzky’s lab. Department chair Daniel Talham says that the incident this week involved sodium azide but not benzotriazole-1-sulfonyl azide–the reaction and circumstances were different. Beyond that, they’re still investigating. Adds Talham, “Preliminary investigation determined that appropriate safety procedures and protective equipment were in use, likely significantly mitigating the effects of the explosion.” According to the Gainesville Sun today, the Katritzky lab is currently barred from using sodium azide and the injured student, Khanh Ha, 27, is still hospitalized with injuries to his face, hands, and body.

Other links of note

  • It’s Friday the 13th! Chemical Space says I wouldn’t do that new reaction today if I were you
  • Washington State adopted a rule to protect healthcare workers from hazardous medications (think pharmacists mixing chemotherapy drugs)
  • The Department of Homeland Security allegedly misled Congress about the effectiveness of a nearly five-year-old program that is meant to secure the nation’s chemical facilities against potential terrorist attacks
  • The Centers for Disease Control & Prevention released its Guidelines for Safe Work Practices in Human and Animal Medical Diagnostic Laboratories

Fires and explosions

  • Is a round-up complete without an entry for Orica’s ammonia planat in Australia? This week, lightening sparked a fire when the plant was venting hydrogen. I really am starting to think that the place is cursed.
  • A worker in India was killed when he tried to cut open an industrial waste drum with an electric cutter; the drum exploded and the worker was then (additionally?) injured by the cutter
  • A boiler system overheated and caused a fire at the Orgahim alkaline paints and resins plant in Bulgaria
  • Something caused a chemical fire in a cabinet at a Micron R&D facility in Boise
  • A Carnegie Mellon professor and student used a fire extinguisher to put out a small fire in a chemistry lab: they “completed some tests, cleaned up, put a chemical inside a container and placed the container in a plastic-lined cardboard box. There apparently was some chemical residual on the container and it reacted with the liner or the cardboard to start the box on fire”
  • What was sodium metal doing in the sink at an Oregon high school? It sounds like the student who turned on the faucet was lucky, since the reported injuries just involve 12 people being treated for respiratory discomfort.
  • Explosions averted: Crystalline picric acid led to the evacuation of a science building at the University of Central Oklahoma and was also found at a former waste management plant in Canada

Leaks, spills, and other exposures

  • Denatonium benzoate, which is apparently very bitter and added to consumer products to keep people from ingesting them, at a U.K. warehouse; 23 people were evaluated for respiratory irritation
  • Ethyl acetate, methyl ethyl ketone, and other chemicals leaked from water-damaged drums at Fermical, “which specializes in the pharmaceutical industry and had been temporarily closed for about a year”
  • Hydrogen fluoride, at Scripps Research Institute in California
  • On roads, railways, and shipyards: sulfuric acid (from a rail yard into a creek in Kansas), diisobutylene

Not covered: meth labs; ammonia leaks; incidents involving floor sealants, cleaning solutions, or pool chemicals; and fires from oil, natural gas, or other fuels.