Essential oil composition of black pepper from Cuba

Pepper (Piper nigrum L.) is one of the world's most important spices, used for both its aroma and pungency. The main exporting countries are India. Sri Lanka, Indonesia, Brazil and Malaysia. The constituents of pepper responsible for its aroma is the steam volatile oil. For more than a century, many studies have been devoted to the chemical composition of black pepper oil and these were reviewed by several authors 2.1 The oil is composed mainly of mono- and sesquiterpene hydrocarbons with minor amounts of oxygenated compounds. Although the oxygenated compounds are relatively minor components, they contribute to the characteristic odor of black pepper 4,3 Essential oil of black pepper finds use in both flavoring and perfumery

PIROLISIS ANALITICA DE SUSTANCIAS HUMICAS

EI aspecto más importante de un suelo es su fertilidad y en esto desempeña un papel muy importante el material humico presente en el. Por sus características físico-químicas las sustancias húmicas tienen gran influencia en la estructura del suelo y en su fertilidad a pesar de las bajas concentraciones en que estás se encuentran con relación a los constituyentes minerales. Las sustancias húmicas son macromolecules orgánicas de estructura caótica y heterogénea, formadas por la modification microbiologica de restos vegetales. Su estructura es lo suficientemente compleja como para que hasta el presente no se tenga una derided total de ellas. El termino estructura en el caso de las sustancias humicas adquiere un significado diferente al que tiene en la química orgánica conventional. A I hablarse de estructura no puede pensarse en una fórmula discreta, pues su formación aleatoria no te permite y todas sus propiedades son promedios de las de innumerables moleculas de comportamiento semejante, pero no idénticas. AI referirse a estructura, se sobreentenderan los bloques estructurales que la conforman

Validation of an analytical methodology for the quantitative analysis of petroleum hydrocarbons in marine sediment samples

This work describes a validation of an analytical procedure for the analysis of petroleum hydrocarbons in marine sediment samples. The proposed protocol is able to measure n-alkanes and polycyclic aromatic hydrocarbons (PAH) in samples at concentrations as low as 30 ng/g, with a precision better than 15% for most of analytes. The extraction efficiency of fortified sediments varied from 65.1 to 105.6% and 59.7 to 97.8%, for n-alkanes and PAH in the ranges: C16 - C32 and fluoranthene - benzo(a)pyrene, respectively. The analytical protocol was applied to determine petroleum hydrocarbons in sediments collected from a marine coastal zone