Determination of antimycin-A in water by liquid chromatographic/mass spectrometry: single-laboratory validation.

An LC/MS method was developed and validated for the quantitative determination and confirmation of antimycin-A (ANT-A) in water from lakes or streams. Three different water sample volumes (25, 50, and 250 mL) were evaluated. ANT-A was stabilized in the field by immediately extracting it from water into anhydrous acetone using SPE. The stabilized concentrated samples were then transported to a laboratory and analyzed by LC/MS using negative electrospray ionization. The method was determined to have adequate accuracy (78 to 113% recovery), precision (0.77 to 7.5% RSD with samples > or = 500 ng/L and 4.8 to 17% RSD with samples < or = 100 ng/L), linearity, and robustness over an LOQ range from 8 to 51 600 ng/L.

Chronic toxicity of diphenhydramine hydrochloride to a freshwater mussel, Lampsilis siliquoidea, in a flow-through, continuous exposure test system.

Freshwater mussel populations are declining in North America. Potential anthropogenic stressors may be contributing to the declines and may include the continual presence of pharmaceutical compounds in waterways. Diphenhydramine hydrochloride (DH) is an over-the-counter antihistamine marketed under several name brand products including the common U.S. trademarked product, Benadryl™. The toxicity of DH to freshwater mussels was assessed by initiating an unprecedented 28 day, continuous exposure trial with 1 day old mussels. Results indicated that the survival and growth of Lampsilis siliquoidea was not impacted by DH concentrations ≤121 µg/L after 28 days of continuous exposure. With the successful completion of this study, the techniques are now verified to evaluate the toxicity of waterborne compounds initiating 28-day chronic exposures with 1 day old mussels.

Chronic toxicity of erythromycin thiocyanate to Daphnia magna in a flow-through, continuous exposure test system.

Approval of a new animal drug application for AQUAMYCIN 100(®) (erythromycin thiocyanate; ET) to treat freshwater salmonid species with bacterial kidney disease is being pursued in the US. As part of the approval process, ET's impact on an aquatic environment had to be described in an environmental assessment. The environmental assessment was lacking data to characterize the effect ET would have on a chronically exposed aquatic invertebrate organism. A major step to fulfilling the environmental assessment was completed after conducting a comprehensive study continuously exposing Daphnia magna to ET for 21 days. Results indicated that the no observable effect concentration for ET was 179 µg/L.

Chronic toxicity of diphenhydramine hydrochloride and erythromycin thiocyanate to daphnia, Daphnia magna, in a continuous exposure test system.

Diphenhydramine hydrochloride (DH; Benadryl™, an over-the-counter antihistamine) and erythromycin thiocyanate (ET; a commonly used macrolide antibiotic) are pharmaceutical compounds whose chronic toxicity to Daphnia magna had not been characterized. Continuous exposure to DH concentrations about 5 times greater than the maximum reported environmental concentration of 0.023 µg/L for 21 days or to ET concentrations about 40 times the maximum reported environmental concentration of 6 µg/L for 21 days did not significantly impact D. magna survival and production. In this study the no observable effect concentration for DH was 0.12 µg/L and for ET was 248 µg/L.

Evaluation of a method for determining concentrations of isoeugenol, an AQUI-S residue, in fillet tissue from freshwater fish species.

AQUI-S is a fish anesthetic/sedative that is approved for use in a number of countries throughout the world and has the potential for use in the United States. The active ingredient in AQUI-S is isoeugenol. A method for determining isoeugenol concentrations in edible fillet tissue is needed for regulatory purposes, including surveillance and potential use in studies fulfilling human food safety data requirements if U.S. Food and Drug Administration approval is pursued. A method was developed and evaluated for determining isoeugenol concentrations in fillet tissue using relatively common procedures and equipment. The method produced accurate and precise results with fillet tissue from 10 freshwater fish species. The percentage of isoeugenol recovered from samples fortified with isoeugenol at nominal concentrations of 1, 50, and 100 microg/g for all species was always >80 and <97%. Within-day precision for samples fortified at those same concentrations was < or =10%, and day-to-day precision was < or =4.0%. Method precision with fillet tissue containing biologically incurred isoeugenol was < or =8.1%. There were no or minimal chromatographic interferences in control fillet tissue extracts from 9 of the 10 species. The method detection limits for all but one species ranged from 0.004 to 0.014 microg/g, and the quantitation limits ranged from 0.012 to 0.048 microg/g.

Residues of the lampricides 3-trifluoromethyl-4-nitrophenol and niclosamide in muscle tissue of rainbow trout.

Rainbow trout (Oncorhyncus mykiss) were exposed to the (14)C-labeled lampricide 3-trifluoromethyl-4-nitrophenol (TFM) (2.1 mg/L) or niclosamide (0.055 mg/L) in an aerated static water bath for 24 h. Fish were sacrificed immediately after exposure. Subsamples of skin-on muscle tissue were analyzed for residues of the lampricides. The primary residues in muscle tissue from fish exposed to TFM were parent TFM (1.08 +/- 0.82 nmol/g) and TFM-glucuronide (0.44 +/- 0.24 nmol/g). Muscle tissue from fish exposed to niclosamide contained niclosamide (1.42 +/- 0.51 nmol/g), niclosamide-glucuronide (0.0644 +/- 0.0276 nmol/g), and a metabolite not previously reported, niclosamide sulfate ester (1.12 +/- 0.33 nmol/g).

Relatively rapid loss of lampricide residues from fillet tissue of fish after routine treatment.

The selective sea lamprey (Petromyzon marinus) larvicide 3-trifluoromethyl-4-nitrophenol (TFM) is currently used to control parasitic sea lampreys in tributaries to the Great Lakes basin. The concentration and persistence of TFM and its major metabolite, TFM glucuronide (TFM-glu), was determined in fillet tissue of fish after a typical stream application. Rainbow trout (Oncorhynchus mykiss) and channel catfish (Ictalurus punctatus) were exposed to a nominal concentration of 12.6 nmol/mL TFM for about 12 h during a sea lamprey control treatment of the Ford River in Michigan. Concentrations of TFM and TFM-glu were greatest in the fillet tissues during the exposure period, with greater residues in channel catfish (wet wt; mean, 6.95 nmol/g TFM; mean, 2.40 nmol/g TFM-glu) than in rainbow trout (wet wt; mean, 1.45 nmol/g TFM; mean, 0.93 nmol/g TFM-glu). After the exposure period, residues in both species decreased by 90-99% within 6-12 h and were less than the quantitation limit (<0.03 nmol/g) within 36 h.