The nitroglycerin found in a Livingston High classroom was a science experiment gone wrong, according to the Merced police detective who helped destroy the explosive compound.
Chemistry teacher Japhia Smith Huhndorf was helping a student with a project focusing on explosives, said Detective Dave Alcaraz of the Merced Police Department bomb squad.
Huhndorf, 34, was arrested Wednesday for the second time in a week after four milliliters of nitroglycerin were found in her chemistry lab. She was previously arrested Monday on allegations that she helped three students inhale chloroform.
Reports of the nitroglycerin prompted school officials to evacuate the campus of all 1,100 students and release classes for the day.
Huhndorf will be arraigned today in Merced County Superior Court.
Alcaraz said Huhndorf explained to police that she allowed Advanced Placement chemistry students to choose subjects for a class project, and one of her students chose to focus on explosives. She found directions for making nitroglycerin on the Internet and made a small amount for the student's experiment, she told police.
"Going through her paperwork, she had several other explosives she could have chosen," Alcaraz said.
Nitroglycerin, it turns out, was a bad choice. Traditionally used in the making of dynamite, the compound can be unstable.
Alcaraz said the bomb squad hasn't had many dealings with nitroglycerin. Most incidents involving the substance have been in Mariposa County and related to old mining and blasting work, he said. "Nitroglycerin is very sensitive to touch and movement. It's something we don't want to have hands-on contact with."
The bomb squad used a robot to move the small vial of yellow, oily liquid to a grassy area on the high school campus, where an explosive charge was placed atop it and set off by a remote detonator.
Livingston Police Sgt. Ray Fong said officers searched Huhndorf's house Wednesday, but nothing was found.
Nitroglycerin doesn't belong in a high school chemistry lab, said Kevin Creed, director of environmental health and safety at UC Merced. The compound is used medicinally by people with certain heart conditions, but the size of the dose can turn it from therapeutic to toxic.
"In a right dose, it's a very good pharmaceutical for heart conditions," Creed said. "They can demonstrate the chemical properties and processes with safer chemicals. They don't have to use nitroglycerin to demonstrate the chemistry they're trying to teach."
All nitroglycerin needs to explode is some sort of energy such as friction, excessive heat or shock if it were dropped, Creed said.
The potential damage from the small amount of nitroglycerin found in Huhndorf's classroom would depend on the situation, he said.
"If it is contained in a glass vial in a storage closet, in close quarters, and explodes in there, there is a pressure wave that is generated," he said, and that would do the most damage. "It could be physical (damage) to people or it could break glass, send glass shards shooting," he said.
When properly stored, nitroglycerin is relatively stable, he said. Being in an open space may pose a lesser risk, but is still a significant hazard, Creed said.
"If you take that amount of glycerin and take it in a wide open space and you caused it to detonate, you would make a sound, but it's not going to really harm anything," he explained.
A special permit is needed to buy nitroglycerin, he said.
It's not difficult to make, but the process can be dangerous. Impurities introduced to the compound or improperly controlled temperatures resulting in excessive heat could cause it to explode.
"It has to be in a very controlled lab environment," Creed said.
The bomb squad's method of exploding the nitroglycerin was the proper public safety approach, he said.
Livingston High Principal Ralph Calderon said the school conducts yearly audits of all chemicals on campus and will continue to do so.
Huhndorf, a graduate of the California State University, Stanislaus, teaching program, was hired by the Merced Union High School District as an intern in 2008.
Calls and e-mails to administrators at the district weren't returned Thursday.
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