ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHigh performance liquid chromatographic determination of amino acids in the picomole rangeDennis W. Hill, Frederick H. Walters, Terry D. Wilson, and James D. StuartCite this: Anal. Chem. 1979, 51, 8, 1338–1341Publication Date (Print):July 1, 1979Publication History Published online1 May 2002Published inissue 1 July 1979https://pubs.acs.org/doi/10.1021/ac50044a055https://doi.org/10.1021/ac50044a055research-articleACS PublicationsRequest reuse permissionsArticle Views1243Altmetric-Citations407LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
INTRODUCTION Curry leaf (Murraya koenigii Spreng., Rutaceae), is a popular leafy-spice used in Asian-Indian cuisine for its characterizing authentic flavor and distinct aroma (Fig. 1). The curry leaf is used by Asian Americans originating from South Asia almost daily in its fresh form when available and is preserved as dried or frozen for long-term storage. Interest in greater use of curry leaf has been stimulated since its high antioxidant and anticarcinogenic potential were reported (Khan et al. 1997; Khanum et al. 2000), as well as the changing demographics nationwide that have created a ready market and greater demand for this spice (Palaniswamy 2001). Curry leaf is used in very small quantities for its distinct aroma due to the presence of volatile oils and as a result most studies report on the concentrations of volatile oils and not on the nutritional value and functional properties attributed to antioxidant vitamins and plant pigments. The objective of this study was to evaluate the locally available curry leaves as a source of α-tochopherol, β-carotene, and lutein and study the effect of storage temperature on the concentrations of these vitamins and plant pigments.
Acetonitrile is a commonly used solvent in both industry and research. The treatment of acetonitrile wastes in dilute aqueous solutions with visible light offers advantages to chemical treatment and ultraviolet (UV) irradiation. This study presents the degradation of acetonitrile via a photoinduced electron transfer reaction in the presence of a photosensitizer (dye) and a sacrificial reductant under visible light. Acetonitrile photodegradation (photoreduction) was investigated utilizing a variety of sacrificial reductants and photosensitizers. Optimal results were observed in the presence of methylene green and tri-isopropanolamine with a decrease of acetonitrile in solution to 86% in 24 hours. The only photoreaction product observed was acetaldehyde and a plausible mechanism for the photochemical degradation of acetonitrile is proposed.
A method was developed to determine the fuel/water partition coefficient (KMTBE) of methyl tert-butyl ether (MTBE) and then used to determine low parts per million concentrations of MTBE in samples of heating oil and diesel fuel. A special capillary column designed for the separation of MTBE and to prevent coelution and a gas chromatograph equipped with a photoionization detector (PID) were used. MTBE was partitioned from fuel samples into water during an equilibration step. The water samples were then analyzed for MTBE using static headspace sampling followed by GC/PID. A mathematical relationship was derived that allowed a KMTBE value to be calculated by utilizing the fuel/water volume ratios and the corresponding PID signal. KMTBE values were found to range linearly from 3.8 to 10.9 over a temperature range of 5−40 °C. This analysis method gave a MDL of 0.7 ppm MTBE in the fuel and a relative average accuracy of ±15% by comparison with an independent laboratory using purge and trap GC/MS analysis. MTBE was found in home heating oil in residential tanks and in diesel fuel at service stations throughout the state of Connecticut. The levels of MTBE were found to vary significantly with time. Heating oil and diesel fuel from terminals were also found to contain MTBE. This research suggests that the reported widespread contamination of groundwater with MTBE may also be due to heating oil and diesel fuel releases to the environment.
A major die-off of the American lobster (Homarus americanus) population in Long Island Sound (LIS) occurred in 1999, involving multiple causes, including increases of temperatures, decreasing oxygen concentrations, and pollutants. Other possible affectors were stress to their immune system, microbial population changes, which may have induced shell disease, water acidification, and insecticides. We examined LIS alkylphenol pollution. Alkylphenols, alkylphenol ethoxylates, and bisphenol A (BPA) are produced in excessive amounts, with BPA estimated at 8 billion pounds per year (1 lb = 0.453 kg). Sixty percent of alkylphenols enter the marine environment and have estrogenic endocrine-disrupting effects on vertebrates. We found multiple effects of alkylphenols on lobsters, on larval survival, molting and postlarval molting, shell hardening, and interference in metamorphosis causing larval–juvenile intermediates. We also found evidence for a basic molecular mechanism of action for alkylphenols through juvenile hormone (JH) and ecdysone receptors. Alkylphenols appear to have contributed to the decrease in the LIS lobster population. We recommend remediation, reducing, or eliminating alkylphenols from the marine environment to protect lobsters as well as other organisms.
Rapid detection of DNA damage could serve as a basis for in vitro genotoxicity screening for new organic compounds. Ultrathin films (20−40 nm) containing myoglobin or cytochrome P450cam and DNA grown layer-by-layer on electrodes were activated by hydrogen peroxide, and the enzyme in the film generated metabolite styrene oxide from styrene. This styrene oxide reacted with double stranded (ds)-DNA in the same film, mimicking metabolism and DNA damage in human liver. DNA damage was detected by square wave voltammetry (SWV) by using catalytic oxidation with Ru(bpy)32+ (bpy = 2,2'-bipyridine) and by monitoring the binding of Co(bpy)33+. Damaged DNA reacts more rapidly than intact ds-DNA with Ru(bpy)33+, giving SWV peaks at ∼1 V versus SCE that grow larger with reaction time. Co(bpy)33+ binds more strongly to intact ds-DNA, and its SWV peaks at 0.04 V decreased as DNA was damaged. Little change in SWV signals was found for incubations of DNA/enzyme films with unreactive organic controls or hydrogen peroxide. Capillary electrophoresis and HPLC−MS suggested the formation of styrene oxide adducts of DNA bases under similar reaction conditions in thin films and in solution. The catalytic SWV method was more sensitive than the Co(bpy)33+ binding assay, providing multiple measurements over a 5 min reaction time.
A quantification method was developed for the determination of dioctyl sulfosuccinate sodium salt (DOSS) in avian egg samples based on a QuEChERS extraction technique followed by UPLC-MS/MS analysis. DOSS is an anionic surfactant that is part of the Corexit® 9500 dispersive mixture that prevents the formation of oil slicks on water bodies. It was extensively used when the Deepwater Horizon rig exploded and a large amount of crude oil was released into the Gulf of Mexico. QuEChERS provided a simple, effective and time saving sample preparation method prior to analysis without reducing analytical sensitivity and became an excellent substitute to lengthy traditional extraction methods. Weak anionic exchange cleanup significantly reduced matrix effects and improved analyte sensitivity. Ultra-performance liquid chromatography provided an effective separation method, while MS/MS provided the necessary selectivity and increased sensitivity. Our method achieved baseline separation of DOSS, surrogate (sodium octyl sulfate – d17) and the internal standard (sodium dioctyl sulfate – d25), with limits of detection (LOD) and limits of quantitation (LOQ) for DOSS being 260 and 500 pg/mL, respectively. Quality control recoveries were 70.5 ± 7.3% (mean ± standard deviation, n = 3) for the laboratory control sample and 72.4 ± 4.9% (n = 3) for the matrix spike. The extraction efficiency was monitored by adding surrogate compound to every sample with recoveries of 104.6 ± 14.1 for SDS-d1 and 81.8 ± 6.8 for SOS-d17. Currently, limited peer reviewed scientific data are reported on the effects of oil dispersants on the environment. Our analytical method for the determination of DOSS in avian egg matrix can be used to provide reliable data on the fate and effects of DOSS in biological systems.
Damage of DNA films after reaction with styrene oxide was detected using derivative square wave voltammetry. Double-stranded (ds) DNA films with initially low backgrounds developed oxidation peaks for DNA bases during incubation with styrene oxide. Films were prepared on pyrolytic graphite (PG) electrodes by casting mixtures of DNA with the poly(ester sulfonic acid) ionomer Eastman AQ38S or by covalent binding of DNA onto oxidized PG. While both types of films gave oxidation peaks in the region 0.6−1.1 V vs SCE after incubations with styrene oxide, DNA/AQ films gave the best signal-to-background ratios. Damage of DNA by reaction with styrene oxide under the electrode incubation conditions was confirmed by capillary electrophoresis. Total integrals of oxidation peaks increased with time of incubation with styrene oxide. Relative peak heights depended on the type of DNA in the order calf thymus ds DNA > salmon sperm ds DNA > supercoiled ds DNA > highly polymerized calf thymus ds DNA.
