Development of extraction and detection method for fluridone in water and sediment by HPLC-UV.

Fluridone is widely used as a herbicide for controlling invasive aquatic plants such as hydrilla in surface water bodies. When applied on surface waters fluridone can attach to bed sediment, requiring rigorous extraction methods prior to analysis. Currently, very limited information exists in terms of fluridone residue detection in delta sediment. In this study, we researched fluridone detection in both water and sediment. To extract fluridone from sediment, here we have tested two extraction methods: (1) a rotavapor method (RM); and (2) a quick, easy, cheap, effective, rugged and safe (QuEChERS) method (QM). The extraction results of RM were compared with those of QM. To quantify fluridone concentrations in extracts, a high-performance liquid chromatography (HPLC)-UV detector was used. HPLC separation was achieved using an Allure C18 5 µm 150 × 4.6 mm column with a mobile phase composed of acetonitrile and water (60:40, v/v). The UV detector was operated at 237 nm. The method was tested and validated using a series of water and sediment samples taken from Sacramento-San Joaquin Delta in California. The average recovery of fluridone was 73% and 78% using RM and QM respectively. The proposed method can be used for testing fluridone in water and sediment samples.

Sub-lethal effects of herbicides penoxsulam, imazamox, fluridone and glyphosate on Delta Smelt (Hypomesus transpacificus).

Concerns regarding non-target toxicity of new herbicides used to control invasive aquatic weeds in the San Francisco Estuary led us to compare sub-lethal toxicity of four herbicides (penoxsulam, imazamox, fluridone, and glyphosate) on an endangered fish species Delta Smelt (Hypomesus transpacificus). We measured 17ß-estradiol (E2) and glutathione (GSH) concentrations in liver, and acetylcholinesterase (AChE) activity in brain of female and male fish after 6 h of exposure to each of the four herbicides. Our results indicate that fluridone and glyphosate disrupted the E2 concentration and decreased glutathione concentration in liver, whereas penoxsulam, imazamox, and fluridone inhibited brain AChE activity. E2 concentrations were significantly increased in female and male fish exposed to 0.21 µM of fluridone and in male fish exposed to 0.46, 4.2, and 5300 µM of glyphosate. GSH concentrations decreased in males exposed to fluridone at 2.8 µM and higher, and glyphosate at 4.2 µM. AChE activity was significantly inhibited in both sexes exposed to penoxsulam, imazamox, and fluridone, and more pronounced inhibition was observed in females. The present study demonstrates the potential detrimental effects of these commonly used herbicides on Delta Smelt.

Acute toxicity of peroxy sulfonated oleic acids (PSOA) to freshwater aquatic species and sludge microflora as observed in laboratory environments.

BACKGROUND: Peroxy sulfonated oleic acids (PSOA) is a novel surfactant peracid. The commercial applications of PSOA result in the chemical primarily being disposed of via industrial waste water effluent. Given this manner of disposal, it is important to understand the aquatic hazards of the chemical to better assess the risk posed to aqueous environments. Acute aquatic toxicity laboratory experiments were performed to evaluate aquatic hazards and were conducted according to standard OECD test guidelines with rainbow trout (Oncorhynchus mykiss), water fleas (Daphnia magna) and algae (Pseudokirchneriella subcapitata). In addition, microbial toxicity was evaluated in activated sludge obtained from a domestic sewage treatment facility. RESULTS: Lethal concentration in 50 % of test species (LC50) and effect concentration in 50 % of test species (EC50) values for PSOA ranged from 0.75 to 5.44 mg/L, representing a relatively small range spanning less than an order of magnitude. No observed effect concentration (NOEC) and lowest observed effect concentration (LOEC) ranges were also relatively small, with ranges of 0.25-1.66 and 0.5-3.6 mg/L, respectively. The EC50, LOEC and NOEC values for microbial toxicity were 216, 60 and 20 mg/L, respectively. Predicted no effect concentrations (PNEC) for aqueous media were based on the 96-h LC50 (0.75 mg/L) for O. mykiss, the organism displaying the greatest sensitivity to PSOA. These values were derived for freshwater, marine water and intermittent releases to water and ranged from 7.5 × 10-5 to 7.5 × 10-3 mg/L. A sewage treatment plant PNEC of 2 mg/L was derived based on an activated sludge 3-h NOEC of 20 mg/L. CONCLUSION: These values, along with the anticipated environmental fate and transport for PSOA, were considered in assessing the overall aquatic risk posed by this chemical. Despite the relatively high acute aquatic hazards for PSOA, environmental modeling suggests the overall risk of PSOA to aqueous environments is low based on its anticipated uses. This conclusion is consistent with the significant processing of industrial wastewater by onsite or municipal wastewater treatment facilities prior to release to the environment.

Serotype-specific T(H)1 responses in recipients of two doses of candidate live-attenuated dengue virus vaccines.

As part of a larger vaccine study, peripheral blood mononuclear cells (PBMC) were collected from volunteers for analysis of vaccine-induced T cell responses. The PBMC were re-stimulated in vitro with live dengue virus and assayed for T(H)1 or T(H)2 memory cell responses. Re-stimulated PBMC from the volunteers predominantly secreted interferon-gamma. Little interleukin-4 (IL-4) or IL-10 secretion was detected, indicating a T(H)1 type of T cell response. The interferon-gamma response was primarily serotype-specific with some serotype cross-reactivity. T cell depletion studies showed that the interferon-gamma was being secreted by CD4+ T lymphocytes and/or by cells other than CD8+ T lymphocytes that were being stimulated by the CD4+ T lymphocytes. CD3+ or CD8+ T cell depletion showed that granzyme B mRNA expression correlated with the presence of CD4+ T lymphocytes. However, depletion of CD4+ T cells after four days of stimulation indicated that the granzyme B mRNA was produced by cells in culture other than lymphocytes. In summary, an antigen-specific T(H)1 type T cell response was seen as a response to vaccination using live attenuated dengue virus.