Chemistry PhD not required to make London bombs

Acetone peroxide, the explosive reportedly used by the London bombers last week, is a favoured weapon of suicide bombers in the Middle East.

Anyone with a good high-school knowledge of chemistry and some basic laboratory equipment could make it with ingredients that are widely available in pharmacies and hardware stores a chemistry PhD is not necessary.

The basic requirements, well known to Palestinian and al-Qaeda terrorists, are hydrogen peroxide (a common oxidising agent), acetone (an organic solvent), concentrated sulphuric or hydrochloric acid (as for example in drain cleaning fluids) and ice to cool the reaction.

Acetone peroxide (also known as TATP or the Mother of Satan) has been known since the 19th century. It does not have commercial or conventional military applications because more stable explosives are available that last longer in storage and are safer to transport.

But acetone peroxide appeals to some foolhardy non-terrorist amateurs, who like to make small quantities of their own explosives for pyrotechnic “fun”. Last year, for example, two teenagers were arrested in the US for making acetone peroxide from materials they had stolen from their school laboratory. Recipes for making anything nasty from an atomic bomb to ricin poison can be found on the internet and acetone peroxide is no exception.

The material first came to public attention in the west in 2001 when it was discovered that Richard Reid, the would-be “shoe bomber”, had packed a mixture of acetone peroxide and plastic explosive into his basketball shoes.

It is better known in Israel because Palestinian bombers frequently use acetone peroxide; dozens of Palestinians have reportedly been killed making or handling the material when it exploded prematurely.

Acetone peroxide is not easily detected by conventional instruments though dogs can be trained to sniff out the small amounts of acetone that remain in the explosive. However Israeli scientists are developing new techniques to detect it and related “peroxide explosives”, in response to their increasing use by terrorists.

“The impact of a bomb made with TATP is similar to a commercial or military high explosive,” says John Wyatt, a British counter-terrorism explosives expert. “The extent of structural damage caused depends on the surrounding area for example a stronger structure builds up the pressure and the force of the bomb.”

Pure acetone peroxide a white crystalline powder is probably too unstable and liable to accidental detonation for the London bombers to have risked packing it into their rucksacks on its own. To make it more controllable, the acetone peroxide may have been mixed with another material, the identity of which has not been revealed by the police.

However acetone peroxide decomposes quite fast, even when mixed and stored under optimal conditions, so it is likely that the explosives in the London bombs were manufactured within a week of their use.