Author: Dan Kuespert

Laboratory Safety Advocate for the Johns Hopkins University Homewood Campus. I am a Ph.D. chemical engineer and Certified Safety Professional with experience in industrial research, nonprofit management, and chemical safety consulting. My role is to promote a culture of safety at Homewood by working with faculty, staff, and students to bring safety expertise into the laboratory.

HPLC waste handling

Many labs at Homewood use High Performance Liquid Chromatographs (HPLCs); these instruments allow separation and analysis of a wide variety of chemicals in small quantity. HPLCs use carrier solvents, chemicals that carry the compounds being analyzed through the machine. Consequently, HPLCs can produce large amounts of chemical waste. This can lead to several problems.

  1. Laboratories sometimes place HPLC waste containers on the floor where they can be kicked. Not only can this cause a chemical spill, but it can also result in physical injury to researchers to accidentally kick or trip over the waste bottle. This risk is easily mitigated by placing the waste containers off the floor—on the bench, in a cabinet, etc.
  2. HPLC waste containers are sometimes stored without secondary containment, that is, a tray or outer bottle to prevent leaks from spreading. Secondary containment must be large enough to contain the entire contents of the leaking waste bottle, and it must be made of a material (usually plastic) resistant to the chemicals it might have to contain.
  3. Sometimes, laboratories will route HPLC waste lines directly into bottles such as recycled solvent bottles. While there is nothing wrong in principle with this, there are several issues.
    • Often, the tubing is routed into the waste bottle without any consideration for overflow. Special purpose valves, often built into specialty bottle caps, are available to shut off flow in the waste line if the waste bottle fills up. Most HPLCs will shut themselves off if the waste line is blocked—check your instrument manual.
    • Sometimes, the tubing is secured and “sealed” to the bottle with aluminum foil or Parafilm—this is ineffective in stopping vapor from being released into the lab. The result is that all lab occupants must breathe the vapor from the HPLC waste; this is also an environmental violation. Again, special HPLC collection systems and bottle caps are available to provide a positive seal.
    • Using recycled bottles can also be an issue if the original contents of the bottle are not compatible with the HPLC waste. Never use reactive chemical bottles such as those for nitric or perchloric acid for solvent waste, regardless of how well you think you’ve cleaned them.

Secondary containment tubs and overpacks are available from laboratory equipment suppliers such as Fisher Safety. Other suppliers, such as Cole-Parmer, make sealed HPLC cap systems. Contact the Laboratory Safety Advocate, Dr. Daniel Kuespert, CSP, at [email protected]for assistance in obtaining special cap systems suitable for your instrument.

Managing experimental scope changes

All experimental protocols have a scope—that is, every experiment has parameters such as pressure, temperature, power, force, chemical identity, etc.

Many people think that performing safety analysis on an experiment is “too much trouble” because they don’t want to have to do it each and every time they change a parameter. This is not true; such people misunderstand how to use safe experimental design methods.

When we plan an experiment, the range of parameters we expect—pressure ranging from 0 to 50 bar, for example, defines a set of safe operating conditions– what I like to call a sandbox. Provided you do an appropriate safety analysis for the range of safe operating conditions you expect to use in your experiment, you can do experiments anywhere within the sandbox you like. Want to move your 5 bar experiment to 15 bar? If your safe operating pressure is defined as 0—50 bar, no additional safety analysis is necessary.

It is only when we leave the sandbox—vary parameters outside the range we’ve already studied—that additional safety analysis is needed. Recognizing when you have a need to vary outside your known safe parameters and doing the appropriate safety analysis—expanding your sandbox—to verify that the variation is safe is called Management of Change.

So an efficient and safe experimental design takes into account the widest anticipated variation in parameters—it makes the sandbox as big as possible. This requires a little thought at the beginning of an experimental series: exactly how hot might you need to operate? Exactly which chemical solvents might you need to use? It takes far less time to do safety checks on a broad scope of experimentation than to do smaller ones piecemeal during lab work—and it is far more likely to be done properly because you won’t be in a hurry to get back to the bench.

If you would like assistance in safe, efficient, broad-scope experimental design, contact the Laboratory Safety Advocate, Dr. Daniel Kuespert, CSP, at [email protected].

Got nanomaterials?

Nanomaterials pose challenging health & safety issues, because the toxicity and other biological effects of many nanomaterials are unknown. It is entirely possible that nanomaterials can be much more dangerous than the base materials. For example, a lump of coal or a diamond is relatively nonhazardous, but carbon nanotubes have long been suspected of asbestos-like action on the lungs, leading to lung and pleural lining cancers. [https://blogs.cdc.gov/niosh-science-blog/2008/05/20/nano/]

The Centers for Disease Control and Prevention’s National Institute of Occupational Safety and Health recently issued four documents describing best practices for working with nanomaterials, including [items from CDC press release cited below]

• Handling and weighing of nanomaterials when scooping, pouring, and dumping;
• Harvesting nanomaterials and cleaning out reactors after materials are produced;
• Processing of nanomaterials after production;
• Working with nanomaterials of different forms, including dry powders or liquids.

The last item, working with nanomaterials, comes in a poster format suitable for hanging in the lab; the others are guidance documents.

It is strongly advised that researchers and principal investigators working with nanomaterials familiarize themselves with these documents, since they represent known best health & safety practice for their work.

The documents may be found on the CDC website at https://www.cdc.gov/niosh/updates/upd-03-12-18.html

Warning: Graphite oxide explosions

Graphite oxide (GO; also known as graphene oxide) is an intermediate compound used in its own right and as a route to graphene. Several papers over the last few years have indicated that bulk GO, when heated, can explode; samples of a few milligrams created energy releases that damaged laboratory equipment. (Qiu, Y., et.al. Explosive thermal reduction of graphene-oxide based materials: Mechanism and safety implications. Carbon 72, 2014, pp215-223. Doi: https://doi.org/10.1016/j.carbon.2014.02.005)

Self-heating is also possible, particularly with addition of dopants such as hydroxyl ions (-OH), which drop the temperature for thermal runaway by as much as 50˚C. Such a reduction can overlap with common processing temperatures for GO.

Results presented at the recent American Chemical Society meeting in New Orleans (Green, M.J., et.al. Study of safer storage of graphene oxide. Paper number CHAS 3.) indicate that the temperature at which thermal runaway/explosion occurs drops as the amount of material increases due to mass and thermal transfer effects.

Storage of substantial quantities of GO therefore may pose both a laboratory and a process hazard. It is recommended that researchers working with this material minimize storage, perform a thorough literature search before heating GO, and take appropriate precautions to protect against mishaps.

Warning: Laser eye protection for ultrafast lasers may not be protective

Laser eye protection is normally rated using continuous-wave, narrow-bandwidth lasers. Nevertheless, some labs use pulsed lasers, which have wider bandwidths and higher peak powers; in the case of pico- and femtosecond pulses, this is taken to extremes.

Recent work at NIST and Hood College in Frederick, MD, has shown that much laser protective eyewear is not capable of withstanding fast laser pulses. (J. Laser Appl. 2017, DOI: 10.2351/1.5004090) 22 different pairs of eye protection were tested against a 40-80 fs pulsed laser, and more than half failed to perform as rated. All plastic protective lenses failed.

It is strongly recommended that when selecting laser protective eyewear, you test the eyewear against your particular use condition to ensure that they provide adequate protection. The Laser Safety Advocate, Niel Leon, is available to assist with testing of this sort.

Further information can be found in the cited paper and in this article in Chemical & Engineering News.

Hazard assessment resources from the ACS

Hazard assessment is an important part of the overall process of controlling hazards in the laboratory. The American Chemical Society recently developed a website that gives detailed information and tools for doing hazard assessments–tools that apply not only to chemistry but to all laboratory research.

I encourage all researchers to look at the ACS’s site to see what lessons can be learned. If you would like an introduction to the resources available or a “teach-in” on a particular part (e.g., standard operating procedures–what we call “experimental protocols” in academia), please contact me at [email protected].

Warning: Azidophenylalanine

The unnatural amino acid azidophenylalanine is used for modifying and labeling proteins in biological and biochemical research. The azido group, though, is often a bad actor, leading to “energetic events,” (i.e., explosions).

A recent article in J. Org. Chem. (doi:10.1021/acs.joc.8b00270) by Mark Richardson, Gregory Weiss, and other University of California researchers describes an inexpensive synthesis of this amino acid. In the course of the research, the researchers studied the intermediates and final product using differential scanning calorimetry and discovered that azidophenylalanine “behaved like an explosive compound,” an unexpected result. The authors recommend that crystalline samples of azidophenylalanine not be stored for long periods and that all stocks of the material be kept in dilute aqueous solution.

Further details can be found in a Safety Note in Chemical & Engineering News.

Keep an accurate chemical inventory

 

Having an up-to-date chemical inventory is important for efficient laboratory operations, but it is essential for emergency responders. By agreement with the Baltimore City Fire Department, each JHU laboratory containing chemicals must post an up-to-date chemical inventory on the entry door. It is the lab’s responsibility to maintain its inventory.

In practice, the inventory need include only the full English common name of the chemical (or the IUPAC name if there is no common name) and maximum quantities stored or used in the lab. The inventory must be updated before the annual Health, Safety, and Environment inspection in the Fall, but best practices would be to update quarterly or monthly, depending on the rate of chemical transfer in and out of the lab.

Please make an effort to ensure that your laboratories meet JHU’s commitment to the Fire Department. Accurate information on a lab’s contents allows the Fire Department to protect themselves more effectively and to minimize damage to a lab experiencing an emergency.

Learn the fundamentals of toxicology in your spare time

The National Library of Medicine makes available an online short course on toxicology available at https://toxtutor.nlm.nih.gov/index.html. ToxTutor even offers a certificate of completion if you sign up for the Library’s free learning management system.

Another good nonspecialist introduction to toxicology is The Dose Makes the Poison: A Plain-Language Guide to Toxicology (Frank, P., Ottoboni, M.A.; Wiley, 2011). This book provides an excellent introduction to toxic chemical hazards and is recommended for those who handle a variety of chemicals.