Electron capture detector (ECD). Electron capture detectors (ECD) are typically used in environmental testing for detecting PCBâs, organochlorine pesticides, herbicides and various halogenated hydrocarbons. With an electron capture detector, a beta emitter such as radioactive tritium or 63Ni is used to ionize the carrier gas.
Las Piedras: Las Piedras, city, southern Uruguay. It is situated in a wine-growing district just north of Montevideo. It was the site of a decisive battle (1811) in Uruguayâs struggle for independence, in which the revolutionaries defeated Spanish forces. Las Piedras is among the largest cities in Uruguay. It is known for its ostrich farming and horse racing. Las Piedras is on the main highway and railroad linking Montevideo with TacuarembÃ³ and Rivera. Pop.
Founded in 1849, the city was renamed Ciudad Porfirio DÃ­az in 1888, in homage to President Porfirio DÃ­az. It reverted to its original name following the Mexican Revolution. In Spanish Piedras Negras translates to black stones â a reference to coal deposits in the area. Across the river, coal was formerly mined on the US side at Dolchburg, near Eagle Pass. This mine closed around 1905, after a fire.