ABSTRACT
Although several methods for the analysis of nitrogen compounds in diesel fuel have been described in the literature, the demand for rapid, sensitive, and robust analyses has increased in recent years. In this study, a comprehensive two-dimensional gas chromatographic method was developed for the identification and quantification of nitrogen compounds in diesel fuel samples. The quantification was performed using the standard addition method and the analysis was conducted using comprehensive two-dimensional gas chromatography coupled with fast quadrupole mass spectrometry. This study is the first to report quantification of nitrogen compounds in diesel fuel samples using the standard addition method without fractionation. This type of analysis was previously performed using many laborious separation steps, which can lead to errors and losses. The proposed method shows good linearity for target nitrogen compounds evaluated (m-toluidine, 4-ethylaniline, indole, 7-methylindole, 7-ethylindole, carbazole, isoquinoline, 4-methylquinoline, benzo[h]quinolone, and acridine) over a range from 0.05 to 2.0 mg/L, and limits of detection and quantification of <0.06 and 0.16 mg/L, respectively, for all nitrogen compounds studied.
ABSTRACT
OBJECTIVE: Many neurosurgeons consider cerebral aneurysms to be rare in Africa and the Middle East. In this report, we describe the pattern of cerebral aneurysms in Morocco and call into question the idea of their rarity in developing countries. Our objective is to urge neurosurgeons in these areas to track them and to treat them under better conditions. METHODS: We report a retrospective study of 200 patients with cerebral aneurysms admitted to our department between 1983 and 1999. The results of this study are supported by pertinent epidemiological surveys, anatomic studies on the incidence of cerebral aneurysms in Morocco, and analysis of the literature related to the epidemiology of aneurysms in developing countries. RESULTS: The patients in our series ranged in age from 7 to 70 years (mean age, 52 yr), with a slight female predominance (52%). They presented with subarachnoid hemorrhage (173 patients), cranial nerve palsy (18 patients), or mass symptoms (9 patients). The delay between subarachnoid hemorrhage and admission ranged from 1 to 30 days (mean, 14 d). The aneurysm was located in the internal carotid artery in 42%, in the anterior communicating and anterior cerebral arteries in 28%, in the middle cerebral artery in 19%, and in the vertebrobasilar artery in 10%. Multiple aneurysms were encountered in 9% and giant aneurysms in 15.5%. Seventeen patients died before surgery (with vasospasm in 13 cases and rebleeding in 4 cases), and 19 died after surgery. Follow-up, ranging between 1 and 10 years, revealed good outcomes with complete recovery in 64.5% and recovery with major sequelae in 7%. Pre- and postoperative mortality represented 18%; there was no operative treatment and no follow-up in 11.5%. CONCLUSION: Some data in this study (the delay between subarachnoid hemorrhage and admission, the high incidence of urban patients [80%], and the high rate of giant aneurysms) explain why many cases of ruptured aneurysms are not diagnosed. The analysis of our clinical series and the results of the epidemiological surveys show that the incidence has doubled every 5 years. These findings confirm that cerebral aneurysms are not rare in Morocco. A critical reading of the published articles claiming a low incidence of cerebral aneurysms in Africa, the Middle East, and Asia shows that this conclusion is not based on accurate and reliable statistical studies. Neurosurgeons in these regions should abandon this idea of rarity, and they should search for arterial cerebral aneurysms and develop the optimum conditions for the treatment of patients with aneurysms.
