Transportation and fate of cationic surfactant in river water.

The degradation, sorption, transportation and material balance of cationic surfactants discharged from domestic waste into river water was studied. Ion-pair solid-phase extraction behavior showed that the sorption of cationic surfactants as an ion-pair with anionic surfactant onto river sediment was so strong that little cationic surfactant was found in the bulk water. Cationic surfactant was found in river sediment at more than 500 times higher concentration than that in the bulk water. The degradation of the cationic surfactant was very slow in river water and much slower in the sediment. A material balance of cationic surfactant was estimated for a river running through Toyama City by measuring the flow rate and the concentration of cationic surfactant in the water at several points. It was found that more than 30% of cationic surfactant introduced to the river was lost during the river running through ca. 3 km in 3 h. This reduction probably comes from a quick transfer of the cationic surfactant from river water to sediment and water weed by means of adsorption or precipitation with suspending solids.

Extraction and separation of cationic surfactants from river sediments: application to a spectrophotometric determination of cationic surfactant in an aquatic environment using membrane filters.

The quantitative extraction of cationic surfactant (CS+) in river sediments was studied. Further, the developed method was applied to the spectrophotometric determination of CS+ in urban river sediment samples by solid-phase extraction with membranes. A mixture of methanol and hydrochloric acid was proposed as an eluent. Dried sediment was digested in the eluent under ultrasonic irradiation. After elution, the eluent was evaporated to almost dryness. The residue was dissolved in a small volume of methanol and diluted to a certain volume with water. The pH of the solution was adjusted to 4-5 to separate iron and some other metals as precipitates of hydroxides. The solution was passed through two-piled membranes: first glass-fiber and then polytetrafluoroethylene (PTFE) membranes. A small volume of methanol was passed through the membranes to elute any CS+ retaining on the membranes. After passing the methanol solution through a cationic exchange resin column, the retained CS+ was eluted with methanol containing a high concentration of sodium chloride. Water, Bromophenol Blue (BPB) and hydrochloric acid were added to the solution. The solution was passed through a mixed cellulose ester membrane filter to retain an ion associate of CS+.BPB-. The retained ion associate was dissolved in a small volume of N,N-dimethylformamide together with the membrane filter, followed by the addition of triethanolamine to make the solution alkaline. The absorbance due to BPB2- was measured at 603 nm against a reagent blank. This method was applied to the determination of CS+ in river water and sediment. A cationic surfactant in sediments at 10(-5) mol kg-1 levels was detected with satisfactory precision. It was found that CS+ was about 500-fold enriched in the sediment from water at the place where domestic wastewater was discharged.

Application of membrane filters for spectrophotometric determination of cationic surfactants in river water and sediment.

Cationic surfactant (CS+) in urban river water and sediment was extracted and determined spectrophotometrically with 2 membrane filters. The CS+ in the water samples, mostly in the form of an ion associate with the coexisting anionic surfactant (AS), was collected on a polytetrafluoroethylene (PTFE) membrane filter and eluted with methanol. Bromphenol blue (BPB), hydrochloric acid, and water were added to the methanol solution successively, and the mixed solution was filtered through a mixed cellulose ester membrane filter. The CS+-BPB- ion associate, formed by a counter ion exchange, was collected on the filter and dissolved into N,N-dimethylformamide (DMF) together with the mixed cellulose ester membrane filter. After addition of 2 drops of triethanolamine, the absorbance of the DMF solution was measured. The CS+ in sediment samples was extracted with methanol by ultrasonic irradiation; the methanol solution was then passed through a PTFE membrane filter and evaporated to dryness. The CS+ was redissolved in a small amount of methanol. For water samples, recoveries and relative standard deviations for 0.30 microM benzyldimethyl-tetradecylammonium ion, a standard material, were > or =93 and < or =5%, with a detection limit of 0.02 microM. Concentrations of CS+ in sediments were much higher than those in water samples, indicating that CS+ is adsorbed on the surface of the sediment.

X-ray fluorescence spectrometric determination of sulfur-containing anionic surfactants in water after their enrichment on a membrane filter as an ion-pair complex with a cationic surfactant.

Anionic surfactants containing sulfur in their structure were enriched on a mixed cellulose ester membrane filter (MF) by filtration as an ion-pair complex with a cationic surfactant. After their enrichment, the anionic surfactants were determined by X-ray fluorescence spectrometry of the sulfur enriched on the MF. A linear calibration was obtained over a concentration range from 0.05 to 0.8 mg L(-1) of sodium dodecyl sulfate as a standard material with less than 6% RSD. The detection limit based on 3s for the reagent blank was 2 microg L(-1). This method is very simple, rapid and highly selective for sulfur-containing surfactants, and does not require any organic solvent extraction. This method was applied to the determination of anionic surfactant in some urban river waters where domestic wastewater was discharged. The results were compared with those obtained by conventional solvent extraction-spectrophotometry. The distribution of the analyte complexes within the MF where the ion-pair was retained is also discussed.

Apoptosis in acute hepatic failure: histopathological study of human liver tissue using the tunel method and immunohistochemistry.

The role of apoptpsis in the occurrence of massive or submassive liver cell death was investigated. Of liver tissues removed from 49 autopsy cases of acute hepatic failure, 26 cases were fulminant hepatic failure (FHF), 13 were subacute hepatic failure (SAHF) and the remaining 10 were acute-on-chronic hepatic failure (AoCHF). Eleven cases were associated with HBV infection, 2 with HCV, 5 with non-A non-B hepatitis, 4 with drug medication and 4 with autoimmune disorder, while the etiology of 23 cases remained unknown. Examinations by the TUNEL method and immunohistochemistry using anti-Fas, -Bax, and -Bcl-2 antibodies were conducted. Most of the FHF and AoCHF cases and half of the SAHF cases showed massive or submassive hepatic lobular injury histopathologically. TUNEL positive cells were observed frequently, and the grade of lobular injury showed significant correlation with the frequency of TUNEL-positive liver cells. Bax and Fas were expressed on the remaining liver cells, while Bcl-2 was seen on the infiltrating lymphocytes. The frequency of TUNEL-positive liver cells showed a significant correlation with Bax expression and the grades of inflammatory cell infiltration, but a poor correlation with Fas and Bcl-2 expression. The results of the present study suggested that apoptosis plays an important role in massive and submassive hepatic cell death. Fas and Bcl-2 might not be involved in the apoptosis of liver cells, but the findings suggested that Bax might play a role in inducing liver cell apoptosis, though the mechanism could not be explained.

Membrane filters for the concentration of trace elements in water: distribution of ion pairs between membrane filter and aqueous phases.

The sorption of ion pairs on membrane filters (MFs) has been studied by taking the membrane filter as one of the homogeneous phases. The sorbability of some ionic species and the sorption abilities of different types of MF were evaluated in terms of the sorption constant defined by Ksor,CA = [(C+,A-)f]/[C+][A-], where C+, A- and (C+,A-) refer to the cation, anion and the ion pair, respectively, and f refers to the filter phase. The values of Ksor,CA were determined for many combinations of ionic complexes of cobalt(III) with pyridylazophenols, either as cations or anions, and oppositely charged organic ions having different alkyl chain lengths, with MFs made of different materials: nitrocellulose (NC; Toyo Advantec), acetylcellulose (AC; Fuji Film), regenerated cellulose (RC; Toyo Advantec) and polyethersulphone (PS; Toyo Advantec). For a given cobalt complex ion, the value of log Ksor,CA increased linearly with the increasing number of carbons in the counter ion. Membrane filters made of different materials showed different sorption abilities, the order being NC greater than PS greater than RC greater than AC. It was shown that the surface area of the MF is of greater significance than the volume of the matrix of the MF in determining the sorption constant.

Application of organic solvent-soluble membrane filters in the preconcentration and determination of trace elements: spectrophotometric determination of phosphorus as phosphomolybdenum blue.

A simple and rapid preconcentration technique, based on collecting trace elements on a membrane filter and dissolving the membrane filter in an organic solvent, has been applied to the spectrophotometric determination of phosphorus in water. Phosphorus, 0.5-7 mug in 50-500 ml of water sample, is collected as phosphomolybdenum blue on a nitrocellulose or acetylcellulose membrane in the presence of n-dodecyltrimethylammonium bromide, the membrane is dissolved in 5 ml of dimethyl-sulphoxide (DMSO), and the absorbance of the DMSO solution is measured at 710 nm against a reagent blank. Moderate concentrations of silicate, anionic and non-ionic surfactants and high concentrations of sodium chloride do not interfere. Interference from arsenate can be eliminated by reducing the arsenate to arsenite. Condensed and organic phosphates can be determined if they are first converted into orthophosphoric acid by digestion with persulphate. The limit of determination is 0.002 mug of phosphorus in 100 ml of sample.

An application of bis[2-(5-chloro-2-pyridylazo)- 5-diethylaminophenolato]cobalt(III) chloride to the extraction and spectrophotometric determination of sulphonated and sulphated surfactants.

Bis[2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) is proposed for the extraction and spectrophotometric determination of sulphated and sulphonated surfactants. The complex and the surfactants form ion-pairs which are extracted into benzene from O.1M hydrochloric acid. The absorbance of the benzene phase is measured at 560 nm against a reagent blank. Less than 25 mug of sodium di-(2-ethylhexyl) sulphosuccinate in 50-200 ml of sample solution is determined reproducibly by the proposed method. When applied to river water samples, the proposed method gives results which agree very well with those obtained by the standard Methylene Blue method. However, the proposed method is simpler and more sensitive than the Methylene Blue method.