Abstract
Gas chromatography-mass spectrometry (GC-MS) is a widely used method for the analysis of volatile and thermally stable organic compounds in which, derivatization of analyte as the determinative step is employed to improve chromatographic characteristics by decreasing its polarity, increase volatility, and detection sensitivity. The traditional derivatization procedures are tedious, time consuming, laborious, and often result in evaporative losses of analytes of interest. Thus, alternative approaches involving minimum sample preparation and on-line derivatization have attracted researchers. In this study, phenyltrimethylammonium iodide (PTMA-I) ion-pair reagent has been used for online derivatization of compounds with polar functional groups like acids, phenols, and carboxyamides. Tetramethylammonium hydroxide (TMA-OH) ion-pair reagent was employed for on-line derivatization of hydroxyl groups containing endocrine disruptors (EDs) including nonylphenol (NP), bisphenol A (BPA), diethylstilbestrol (DES), and 17-beta-estradiol (Estradiol) during the determination of endocrine disrupters in surface water. Chemical ionization mass spectrometry (CI MS) is a softer ionization technique than electron ionization mass spectrometry (EI MS) which enables concentration of the total ion current among structurally relevant compounds providing information of ion indicative of the molecular weight and structure. Thus, use of many unusual chemical ionization reagents for selective detection and quantification of compounds in complex matrices have been attempted in the past. In this work, the ion-molecule reactions of nine monosubstituted naphthalene compounds were studied using tetrahydrofuran and furan as CI reagent in chemical ionization mass spectrometry (CI MS). Proton affinity factors, substituent effects, and the preferred site of adduct ion attachment were also examined. Collision activated dissociation experiments were used to characterize the variety of adducts formed under CI condition, and provided insight into product ion structures, and mechanisms of dissociation and condensation during CI MS/MS. Moreover, a simple, rapid, and sensitive method for the simultaneous determination of amphetamines in trace amounts of urine sample has been developed. The method uses GC direct sample introduction (DSI) device for on-line derivatization of amphetamines. Further use of laboratory-built multiple CI reagent system to introduce furan as CI reagent with tandem mass spectrometry improves the sensitivity and selectivity. The method uses only 20 □L of urine sample and spares pretreatments like extraction or cleanup. Sharp analyte peaks with relatively low background from impurities was noted. The limits of detection (LODs) for each amphetamine range from 0.4 to 1.0 ng mL-1. The linearity was examined using stock standard solutions between 1.0 and 500 ng mL-1 and all analytes show good linearity with correlation coefficients of r2 > 0.999. A good recovery (86 to 112 %) was obtained using five spiked samples. The RSDs range from 5.4 to 18.1 %, indicating good repeatability. The recently developed electronic nose (EN) for odor detection has been reported as a simple and rapid technique. It finds enormous applications in the food industry, bacterial metabolism, odor identification, and environmental monitoring. In this study, two electronic noses (EN), different in operational principle, were used for identifying the source of spilled oil in an accident. Use of traditional GC-MS not only confirm the identified spilled oil source but also provides detailed diagnostic information such as total petroleum hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and their C1-C4 alkylated homologues, as well as the n-alkanes, which are essential for follow-up remedial and regulatory actions. The main use of the electronic nose was demonstrated to be as a simple and rapid method for identifying a spilled oil source.