Exploding pumps trigger Sciex mass spectrometer alert
Mar29

Exploding pumps trigger Sciex mass spectrometer alert

From Marc Reisch’s story at C&EN: Scientific instrument maker Sciex has told owners of more than 2,000 mass spectrometers to immediately shut down the instruments because a catastrophic failure of turbo pumps manufactured by Agilent Technologies could “result in serious injury or death.” To date, Sciex says, no one has been injured. According to a safety notice dated March 13 for owners of API 4000, API 4000 Qtrap, and API 5000 model mass spectrometers, the rotors of the TV 801 turbo pump can suddenly fragment and be ejected at high speeds. The pumps are used to create a high negative pressure in the instrument’s vacuum chamber. For more, go read Marc’s story or see the information on Sciex’s...

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From the archives: UC Berkeley lab demolished when molten salt bath explodes
Mar01

From the archives: UC Berkeley lab demolished when molten salt bath explodes

More from last week’s trip into the C&EN archives. From Oct. 11, 1982: Molten salt baths cited as lab hazards A University of California, Berkeley, lab has been rebuilt and is ready for use again after being demolished in late July by the explosion of a molten salt bath. Berkeley chemistry and chemical engineering faculty members are concerned that many researchers are unaware of the potential dangers of these commonly used heat-transfer media. The explosion involved a glass polymer-synthesis apparatus immersed in a fused salt bath containing 3 lb of sodium nitrite and 1 lb of potassium thiocyanate. The bath had been heated above 270 °C using a hot plate. The experiment was being conducted in a closed fume hood. The explosion, which Berkeley faculty members estimate had the force of about 1 lb of dynamite, caused more than $200,000 damage to the new lab. The doors of the fume hood were imbedded in a wall 20 feet from the point of explosion and the interior walls of the lab were bulged outward. The chemical engineering graduate student conducting the experiment escaped probable death only because he was bending over to work on a floor vacuum pump at the time of the explosion. Book references to molten salts imply that they may be used freely, according to C. Judson King, dean of Berkeley’s College of Chemistry. “Molten salts are safe – that’s the message,” he says. Some may be, but others clearly are not. Mixtures of salts for heat transfer are common and are marketed commercially. Such commercial mixtures contain, for example, potassium nitrate, sodium nitrate, and sodium nitrite. King points out that, in the commercial mixtures, all of the components are oxidizers. In the mixture that exploded at Berkeley, thiocyanate, a reducer, was included and seems to have triggered the explosion. Mixtures that contain only nitrate and thiocyanate do not seem to explode. The explosive reaction involved nitrite and thiocyanate. The literature is not of much help in elucidating the problem. The dangers of the mixture are not mentioned in the molten salt safety review in the Journal of Hazardous Materials, King says. An extensive literature review carried out by King unearthed a 1945 Soviet publication that reported that some mixtures of potassium nitrite and potassium thiocyanate exploded when heated above 370 °C. “A small community of industrial chemists is aware of the dangers of molten salt baths,” King says. “However, the information does not seem to have filtered down to the rest of the chemical community.” –Rudy Baum, C&EN San...

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From the archives: Chemists move wall with hydrogen peroxide explosion
Feb22

From the archives: Chemists move wall with hydrogen peroxide explosion

More from my trip into the archives earlier this week. From Nov. 20, 1978: Explosive peroxides SIR: We would like to alert persons to possible hazards involved with the rather common laboratory procedure of dissolving electrophoresis polyacrylamide gels with hydrogen peroxide, in order to measure radioactive species by scintillation counting. Recently a very violent explosion occurred in one of our laboratories which caused complete destruction of a hood and moved a cinder-block wall located 30 feet from the blast. Kick-out panels and glass were blown out of the laboratory and chemicals on shelves in the adjacent laboratory were knocked to the floor. Fortunately the blast occurred when the labs were vacant, or otherwise severe injury or loss of life would certainly have occurred to personnel. The blast apparently occurred due to the formation of explosive peroxides formed from the solubilization of polyacrylamide gels and subsequent counting procedures. The procedure used was basically the following: Polyacrylamide gels (1 cm2) were dissolved with the addition of 0.6 ml of 30% H202, and the resulting solution was added to a scintillation cocktail consisting of a 1:1 mixture of toluene and 2-ethoxyethanol along with scintillation fluors. After the samples were counted for 14C, the contents of all scintillation vials were pooled and concentrated over low heat on a hot plate in the hood. Eventually the radiological safety officer was to dispose of the material. Material had been accumulating in the hood for three to four weeks. Addition of hydrogen peroxide to the polyacrylamide gels could result in the formation of peracids azo- or nitro-compounds. This mixture was then added to the toluene-ethoxyethanol cocktail, and hydrogen peroxide not used in solubilization of the gel could form explosive adducts with the ether. Tests of a commercial cocktail mixture showed that peroxides were present even before the hydrogen peroxide was added. The procedure used for dissolving the gels is used by many laboratories and had been used for three years in our labs without incidence. We recommend that either alternate methods be used to solubilize the gels or that the peroxides be immediately destroyed after scintillation counting. –Dennis W. Darnall, Professor of Chemistry, New Mexico State University, Las Cruces And a response, from May 21, 1979: SIR: This is in response to Prof. D. W. Darnall’s chemical safety letter on “Explosive peroxides” in C&EN, Nov 22, 1978, page 47. It is by no means necessary to invoke the formation of an organic peroxide to understand the explosion described by Darnall. Mixtures containing strong hydrogen peroxide and soluble organic matter have been known to be explosive for many years. See, for example, E. S. Shanley and F....

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From the archives: Chemists lose hands from peroxide explosions
Feb21

From the archives: Chemists lose hands from peroxide explosions

Regarding the inadvertent synthesis of TATP at the University of Bristol, someone commented at “In The Pipeline”: I recall a C&EN story from the early 1980s about a group at K (Kansas or Kentucky?) preparing a batch of 100% H2O2. It exploded during purification and blew off a corner of the building. I vaguely recall a picture of the lab walls completely blown out. I believe they (Kansas? Kentucky?) shut down their chemistry program after that incident before restoring it after a couple of years. I dug into our archives to see if I could find the incident in question. I haven’t been able to find it, but I did dig up some other interesting stories: From July 21, 1952: Chemist Loses Hand in Performic Acid Explosion Five milliliters of performic acid exploded recently at Laval University, Quebec, Canada, tearing off the right hand of a graduate student and smashing all glassware in a radius of 2 to 3 feet. Numerous glass slivers were driven into his skin and into one of his eyes. According to information from the student, A. Weingartshofer-Olmos, and Paul A. Giguere, professor of physical chemistry at Laval, a small receiving flask containing the 5 ml of approximately 90% performic acid was being removed from the still when it detonated for no apparent reason. The acid had been prepared by the addition of 25 grams of 99% hydrogen peroxide to 20 grams of 99% formic acid in the presence of 6.5 grams of concentrated sulfuric acid as catalyst. After two hours for reaching equilibrium, the mixture was distilled under reduced pressure (5 to 10 mm Hg) at 30° to 35° C. This preparation had been performed several times before in the same manner without any mishap. The material was known to be dangerous and adequate precautions were taken. All glassware was thoroughly cleaned in fuming sulfuric acid. The distillation apparatus was entirely assembled through ground glass joints and no lubricant of any sort was used. The still was connected to a dry-ice trap, manometer, and vacuum pump through a length of Tygon tubing. Only 5 to 10 milliliters of the acid was prepared at a time. As nothing unusual had happened while the material was heated for distillation and as the distillate was kept at —10° to — 15° C , the operator felt that the danger period was over. He removed his face shield, pushed aside the two safety screens, and reached for the receiving flask. As he was about to touch the discharge tube to collect a pendant drop, the flask exploded. Like all peroxides and ozonides, performic acid is unstable, since it...

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How a student unintentionally made an explosive at U Bristol
Feb15

How a student unintentionally made an explosive at U Bristol

Last week, the Safety Zone reported that a University of Bristol student had unintentionally made approximately 40 g of triacetone triperoxide (TATP), prompting building evacuations and a controlled detonation by an explosives team. Here’s a statement about the incident, prepared by Timothy C. Gallagher, a chemistry professor and dean of the Faculty of Science, and Nicholas C. Norman, head of the school of chemistry. On 3 February 2017, a graduate student in the School of Chemistry at the University of Bristol was carrying out a literature procedure to oxidise an aldehyde to the carboxylic acid using aqueous acidified chlorite. The experiment was carried out on a 5 mmol scale (just under 1g of aldehyde) and risk assessments identifying all hazards had been undertaken and signed off by both student and supervisor. The reaction solvent was acetone (50 mL). Part of the procedure involved adding a quantity of 30% hydrogen peroxide (H2O2) solution to remove some of the by-products of the reaction, whose presence was (apparently) associated with a yellow colour (possibly including chlorine dioxide). The literature indicated that H2O2 be added until this yellow colour had disappeared, which should have required about 1 mL of peroxide solution. The student, focusing on the yellow colour, which did not completely disappear, continued to add hydrogen peroxide solution until about 50 mL had been added. During workup to remove the solvent, the student realised that the solvent volume was not decreasing and that the liquid was becoming viscous, and so likely contained far more “product” than was expected. GCMS analysis indicated the presence of triacetone triperoxide (TATP), and it was estimated that this could amount to 30-40g if all the excess H2O2 had reacted with the acetone solvent. At that point, the graduate student immediately alerted the supervisor, who escalated this to the Head of School. A series of decisions were made and actions taken that resulted in the disposal of the suspected TATP by means of a controlled explosion carried out by the emergency services. Nobody was injured and no damage was done in the lab. Although the TATP presented an explosion hazard, the risk of explosion was considered minor due to all material remaining in solution; TATP is far more sensitive to detonation as a solid. Immediate disposal was warranted, however, due to the risk of precipitation/crystallisation of a solid material. There are lessons to be learned from what happened and some messages. First, the student was concerned with adding hydrogen peroxide to remove the yellow colour (due, at least in part, to chlorine dioxide, which is itself a hazardous material), but overlooked the much greater hazard of adding a...

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Student unintentionally makes explosive at University of Bristol
Feb07

Student unintentionally makes explosive at University of Bristol

A University of Bristol graduate student inadvertently synthesized approximately 40 g of triacetone triperoxide (TATP) on Friday, prompting building evacuations and a controlled detonation by an explosives team, chemistry professor and Faculty of Science dean Timothy C. Gallagher has confirmed to C&EN. No one was injured in the incident. The TATP was in solution and not isolated as a solid. When the student realized what had happened, the student handled the situation very responsibly, Gallagher says. Further response by the department, university, and emergency personnel “went like clockwork,” Gallagher adds. Gallagher says that he is “absolutely convinced” that the preparation of TATP was unintentional rather than deliberate or with malicious intent. Gallagher and others at the university are working to understand exactly how the student came to make the explosive, especially in such quantity. Once that is done, Gallagher plans to share more details and all lessons learned with the chemistry community. “It’s the right thing to do,” he says. Chemist commentary: Chemjobber, Reddit Local news coverage: Epigram (student newspaper), Bristol Post,...

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