Biological transformation, kinetics and dose-response assessments of bound musk ketone hemoglobin adducts in rainbow trout as biomarkers of environmental exposure.

Low levels (ng/g) of musk ketone (MK), used as a fragrance additive in the formulation of personal care products, are frequently detected in the water and other environment. Thus, aquatic organisms can be continuously exposed to MK. In this study, kinetics and dose-response assessments of 2-amino-MK (AMK) metabolite, bound to cysteine-hemoglobin (Hb) in rainbow trout, formed by enzymatic nitro-reduction of MK have been demonstrated. Trout were exposed to a single exposure of 0.010, 0.030, 0.10, and 0.30 mg MK/g fish. Twenty-seven Hb samples were collected from exposed- and control fish subsequent to exposure intervals of 1 d (24 h), 3 d (72 h), and 7 d (168 h). Basic hydrolysis released bound AMK metabolite was extracted into n-hexane and then concentrated and analyzed by gas chromatography (GC) electron capture negative ion chemical ionization (NICI) mass spectrometry (MS) using selected ion monitoring (SIM). The presence of the AMK metabolite in Hb extracts was confirmed by agreement of similar mass spectral features and retention time with a standard. In the dose-response study, maximum adduct formation was obtained at the 0.10 mg/g dose with an average AMK metabolite concentration of 2.2 ng/g. For kinetics, the highest concentration of the AMK metabolite was found to be 32.0 ng/g at 0.030 mg/g dose in 3-d sample. Further elimination of the metabolite showed kinetics with a half-life estimated to be 2 d, assuming first-order kinetics. The metabolite was not detected in the control samples, non-hydrolyzed Hb, and reagent blank extracts. The detection limit for AMK in the Hb was approximately 0.30 ng/g, based on a signal to noise ratio of 3 (S/N = 3).

Determination of a bound musk xylene metabolite in carp hemoglobin as a biomarker of exposure by gas chromatography-mass spectrometry using selected ion monitoring.

Musk xylene (MX) is widely used as a fragrance ingredient in commercial toiletries. Identification and quantitation of a bound 4-amino-MX (AMX) metabolite was carried out by gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM). Detection of AMX occurred after the cysteine adducts in carp hemoglobin (Hb), derived from the nitroso metabolite, were released by alkaline hydrolysis. The released AMX metabolite was extracted into n-hexane. The extract was preconcentrated by evaporation and analyzed by GC-SIM-MS. The concentration of AMX metabolite was found to range from 6.0 to 30.6 ng/g in the carp Hb, collected from the Las Vegas Wash and Lake Mead, NV areas. The presence of an AMX metabolite in the carp Hb was confirmed when similar mass spectral features and the same retention time of the AMX metabolite were obtained for both standard AMX and carp Hb extract solutions. In the nonhydrolyzed and reagent blank extracts, the AMX metabolite was not detected.

Determination of volatile organic compounds in river water by solid phase extraction and gas chromatography.

A simple, rapid, and reproducible method is described employing solid-phase extraction (SPE) using dichloromethane followed by gas chromatography (GC) with flame ionization detection (FID) for determination of volatile organic compound (VOC) from the Buriganga River water of Bangladesh. The method was applied to detect the benzene, toluene, ethylbenzene, xylene and cumene (BTEXC) in the sample collected from the surface or 15 cm depth of water. Two-hundred ml of n-hexane-pretreated and filtered water samples were applied directly to a C18 SPE column. BTEXC were extracted with dichloromethane and average concentrations were obtained as 0.104 to 0.372 microg/ml. The highest concentration of benzene was found as 0.372 microg/ml with a relative standard deviation (RSD) of 6.2%, and cumene was not detected. Factors influencing SPE e.g., adsorbent types, sample load volume, eluting solvent, headspace and temperatures, were investigated. A cartridge containing a C18 adsorbent and using dichloromethane gave better performance for extraction of BTEXC from water. Average recoveries exceeding 90% could be achieved for cumene at 4 degrees C with a 2.7% RSD.

Formation of nitro musk adducts of rainbow trout hemoglobin for potential use as biomarkers of exposure.

The high use of nitro musk xylene (MX) and musk ketone (MK) as fragrances, and their persistence and bioaccumulation potential make them ubiquitous environmental contaminants. The 4-amino-MX (AMX) and 2-amino-MK (AMK) metabolites have been detected in trout fish hemoglobin (Hb) samples by gas chromatography-ion trap-mass spectrometry (GC-MS). Twelve Hb samples prepared from rainbow trout that were exposed to MX and MK, over a period of 24 and 72 h, were analyzed. Amino metabolites were liberated by basic hydrolysis and extracted from the fish Hb into n-hexane. The extract was concentrated, analyzed, and spiked with a standard solution (80 pg/microl) of AMX or AMK and reanalyzed. Concentrations of AMX from 10 to 25 ng/g were detected in Hb from fish taken 24 and 72 h after MX exposure. At 24 and 72 h after MK exposure, the concentration of AMK was found to be 25-51 ng/g and 9.5-25 ng/g, respectively. Concentrations of AMK in Hb from two of the three trout were substantially lower after 72 h compared with 24 h exposure. The AMX and AMK metabolites were not detected in four control samples. Average recoveries exceeding 89 and 86% could be achieved for AMX and AMK, respectively, with a coefficient of variation (CV) around 5%.

The influence of chlorine on the intensity of metal atomic lines emitted by an electrolyte cathode atmospheric glow discharge.

The effect of different matrix anions in the solution on the intensity of metal atomic lines was investigated. A significant increase in intensity was found for chloride anions compared with nitrate and sulfate anions. This effect was even greater when the appropriate acids were applied. A further enhancement of the metal line intensities could be observed when HCl was used in the solution phase and simultaneously elemental chlorine was mixed with atmospheric air at levels up to 6-10 vol.%. This double effect was especially high for the Cu, Ni and Pb resonant atomic lines at higher chlorine-to-air ratios in the gas phase, and the W-anode tip was destroyed by chemical burning. The application of volatile organic chlorine compounds (carbon tetrachloride and chloroform) in the gas phase, even without any acidification, also caused an enhancement of the metal line intensities. The experimental results can be attributed to the different rates of the ion-ion (positive metal ion-negative chloride ion) and the positive metal ion-electron recombination processes taking place in the cathode dark space of the discharge plasma, yielding neutral metal atoms for excitation. This study is important for the on-line measurement of heavy metals in liquids.

Application of an HPLC-FTIR modified thermospray interface for analysis of dye samples.

Previously, we developed a reversed-phase HPLC method compatible to high performance liquid chromatography diffuse reflectance Fourier-transform infrared (HPLC-FTIR) thermospray interface for the analysis of dyes. Dye separation achieved with a mixed-mode (SCX-ODS) column using a small gradient (90 to 80% water with acetic acid) and pH 3.25; 10 to 20% acetonitrile was considered to be suitable for HPLC-FTIR. A constant-voltage setting for the thermospray temperature (227 degrees C) was successfully used for this gradient condition. The HPLC-separated components deposited as a series of concentrated spots on a moving tape were scanned by specially developed HPLC-FTIR software. Excellent repeatability of the thermospray deposition FTIR chromatograms and IR spectra was obtained. The interface-derived spectra of the separated components of formulated and purified reactive dyes were compared and differences in spectral features were observed.