Total Residual Concentration Research Articles

Control of biological iron removal from drinking water using oxidation-reduction potential

Biological removal of iron to produce drinking water was established in a pilot plant treating raw water with a pH of 5.7. The objective was to evaluate the use of oxidation-reduction potential (ORP) as a control tool and determine its relationship to dissolved oxygen (DO) and residual iron concentration in filtered water from an operating biological filter. Results showed that above a low minimum value of DO, residual iron concentration and ORP were not affected by varying the DO level. A non-linear regression was established to correlate total residual iron concentration to ORP with an R2 of 0.8848. This correlation can be used to predict iron concentration when ORP is in the range 300 to 470 mV. Below this range, total residual iron is greater than or equal to 3 mg/l and above, total residual iron is less than the French regulation limit of 0.2 mg/l. Pilot plant operating conditions were implemented in the primary filter of an industrial plant in France, improving iron elimination and doubling the length of the filtration cycle.

Distribution of Radiocarbon After Intramammary, Intrauterine, or Ocular Treatment of Lactating Cows with Carbon-14 Nitrofurazone

Three lactating Holstein cows (634 to 698kg) were dosed, respectively, with 65.6mg (44.5 µCi/mg), 131.2mg (20.1 µCi/mg), or 8.4mg (141.3 µCi/mg) of [14C]nitrofurazone by intramammary, intrauterine, or topical ocular administration. Intramammary and intrauterine treatments were single doses; ocular treatment was daily for 4 consecutive d (2.1 mg/d). Cows were slaughtered after 72-h withdrawal periods. Excreta and milk were quantitatively collected from each cow after dosing. Seventy-two hours after treatment, urine, feces, and milk contained 62.9, 17.6, and 2.3%, respectively, of the radiocarbon administered intramammarily to the cow. Radioactive residues in milk collected from the dosed quarter were 150 ppb (nitrofurazone equivalents) and were 39 ppb in milk collected from the undosed quarters at 12h after dosing. Urine, feces, and milk from the cow that received the intrauterine dose contained 12.24, 5.17, and 0.13% of the administered dose, respectively, at 72h after treatment. Concentrations of total radioactive residues in milk were 9.3 ppb at 12h after dosing. For the cow that was dosed ocularly, the cumulative excretion of radiocarbon in urine, feces, and milk was 17.6, 28.5, and 0.5% of the dose, respectively. Milk residues from the cow that was dosed ocularly were never >1 ppb of nitrofurazone equivalents. Livers and kidneys contained the greatest amounts of residues relative to other edible tissues. Parent nitrofurazone was not suitable as a marker compound to determine total residues in milk using HPLC analysis. Radioactive residues were available systemically and were excreted in milk after intramammary, intrauterine, or ocular application of [14C]nitrofurazone. Illegal residues in milk and edible tissues would result from the administration of nitrofurazone to lactating cows.

Disposition and metabolism of the novel macrolide antibiotic CP-163505 in cattle.

The plasma pharmacokinetics, lung tissue to plasma concentration ratios, and depletion profiles in edible tissue (liver, muscle, kidney, fat and injection site) for a single subcutaneous dose of a novel macrolide antibiotic, CP-163505 (20-[3-dimethylaminopropyl(L-alanyl)amino]-20-deoxo-repromicin), were investigated in crossbred beef cattle. Mean peak plasma concentration of 2.5 +/- 0.4 micrograms/mL, occurring at 0.5 h, was found for CP-163505 following a 5 mg/kg dose (n = 5). The pharmacokinetic profile consisted of a distribution phase, followed by an extended terminal elimination phase (t1/2 of 19 h). The disposition of CP-163505 was characterized by distribution from the plasma into the tissue resulting in lung to plasma ratios of 103 and 87 at 72 h following a single 5 or 10 mg/kg dose, respectively. The depletion of CP-163505 from edible tissues was determined following administration of tritiated CP-163505 at a dose of 10 mg/kg. On day 42, the liver contained the highest mean concentration of total tritium residues, 5.9 +/- 3.4 micrograms/g. CP-163505 was determined to be a significant component of the total residues in liver with 72% on day 3 and 50% on day 42. Three metabolites of CP-163505 were identified by liquid chromatography with mass spectrometry (LC/MS/MS) in liver samples: loss of alanine, formation of an hydroxyl derivative, and sulfate addition to the lactone ring.

Residues and metabolism of 19-nortestosterone laurate in steers.

The illegal use of 19-nortestosterone (19NT; 4-estren-17 beta-ol-3-one; nandrolone) and its esters in livestock, for growth promotion purposes, has been widely reported in the European Union. The target residues for surveillance of abuse in bovine urine and bile samples are 17 alpha- and 17 beta-19NT, although this choice of target residues is not based on in vivo radiotracer biotransformation data. In this study, four steers were administered [3H2]- and [2H3] 17 beta-19NT laurate (2 mg kg-1 body mass) by intramuscular injection and blood, urine, faeces and bile samples were taken for 30 d until slaughter, after which tissues were sampled for total residue analysis. Total plasma radiolabelled residues reached a maximum of 56.3 +/- 15.9 pmol ml-1 at 36 h and were still appreciable (13.3 +/- 1.6 pmol ml-1) 30 d after treatment. Throughout the study period, total residue concentrations in bile (about 2-16 nmol ml-1), urine and faeces (0.5-3 nmol ml-1 or g-1) were higher than in other tissues sampled at slaughter. At slaughter there was evidence of residue accumulation in pigmented eye tissue (33.1 +/- 6.1 pmol g-1) and in white (13.4 +/- 3.4 pmol g-1) and black hair (28.9 +/- 8.9 pmol g-1). Evaluation of radio-HPLC profiles of urine and bile extracts generally indicated that 19NT and 19NT laurate residues were present in relatively small amounts among a complex mixture of metabolites. GC-MS analysis of glucuronidase-hydrolysed bile extracts indicated that the major metabolites were 5 beta-estrane-3 alpha, 17 alpha-diol, 5 alpha-estrane-3 beta, 17 alpha-diol. 5 alpha-estran-3 alpha-ol-17-one (norandrosterone) and estra-1,3,5(10)-triene-3,17 alpha-diol (17 alpha-estradiol).

Control of biological iron removal from drinking water using oxidation-reduction potential

Biological removal of iron to produce drinking water was established in a pilot plant treating raw water with a pH of 5.7. The objective was to evaluate the use of oxidation-reduction potential (ORP) as a control tool and determine its relationship to dissolved oxygen (DO) and residual iron concentration in filtered water from an operating biological filter. Results showed that above a low minimum value of DO, residual iron concentration and ORP were not affected by varying the DO level. A non-linear regression was established to correlate total residual iron concentration to ORP with an R2 of 0.8848. This correlation can be used to predict iron concentration when ORP is in the range 300 to 470 mV. Below this range, total residual iron is greater than or equal to 3 mg/l and above, total residual iron is less than the French regulation limit of 0.2 mg/l. Pilot plant operating conditions were implemented in the primary filter of an industrial plant in France, improving iron elimination and doubling the length of the filtration cycle.

Polychlorinated biphenyls and organochlorine pesticides in EELS ( Anguilla anguilla L.) from Welsh rivers

Organochlorine concentrations in the muscle tissues of eels at 41 freshwater sites across Wales were surveyed in 1993. Positive but weak relationships were detected between eel age or length and the concentration of some organochlorines. Isomers of HCH were below detection at most sites. Dieldrin was widespread at 10–100 μg kt −1 wet weight, despite its ban in sheep dip in 1989. Total DDT residue concentrations averaged 73 μg kg −1. Total PCB burdens expressed as Arochlor 1260, were > 50 μg kg −1 at 76% of sites and > 100 μg kg −1 at 46% of sites. The range of concentrations was comparable with other UK data. Rural sites had relatively low levels of PCBs, highest contamination occurring in the lower reaches of industrialised catchments. The inferences for environmental effects are discussed.

Biodegradation of dissolved jet fuel in chemostat by a mixed bacterial culture isolated from a heavily polluted site.

A mixed bacterial culture capable of biodegrading of jet fuel was isolated from a heavily polluted site in Tapa, Estonia. Residual concentrations of pollutants in the chemostat culture were determined. The total residual concentrations of dissolved jet fuel in culture medium were 0.42 and 2.1 microg l(-1) at the dilution rates 0.1 and 0.17 h(-1) respectively. Benzene, toluene, ethylbenzene, and xylenes were completely degraded and thus not detected in culture broth (detection limit 0.1 microg l(-1)) at the dilution rates 0.1 and 0.17 h(-1). The values of apparent substrate saturation constant (KSapp) in multisubstrate growth conditions were estimated from the experimental data. The residual concentrations satisfy the regulations in the Republic of Estonia for petroleum hydrocarbons (0.00 mg l(-1)--'very good'). Results obtained indicate that use of the biodegradation could be sufficient for the treatment of polluted with kerosene-type jet fuel groundwater up to the acceptable quality.

Optimisation of a purification method for metal-containing wastewater by use of a Taguchi experimental design

A procedure for purifying waters polluted with metal ions has been designed. The method is based on the precipitation of metals as magnetic ferrite from the alkalinised solution containing iron(II). The working conditions were optimised by using a Taguchi L 9(3 4) experimental design in order to minimise the total residual concentration (TRC) of metal ions in solution. A statistical analysis of the experimental data revealed the most influential factor to be the Fe(II)/metal concentration ratio ( F), with a 29.5% contribution, followed by pH ( P, 5.2%) and time ( H, 2.3%). On the other hand, temperature ( T) had little effect on the purification efficiency (1.0%), whereas noise ( N, KMnO 4) was found to contribute by as much as 22.1%. Maximal purification efficiency (99.99%) is achieved when wastewater samples are treated for 3 h at 50°C and pH 10 in the presence of iron(II) in a ratio Fe(II)/total metal of 15. In these conditions, the process efficiency is also the least influenced by variability in the sample composition, which validates the proposed procedure.

Metabolism of14C-sulphadimethoxane in swine

1. 14C-sulphadimethoxine (4-amino-N-(2,6-dimethoxy-4-pyrimidinyl)benzene-[U-14C]-sulphonamide; 14C-SDM) was given orally (60 mg/kg body weight) to eight swine (weight 27-32 kg). Urine and faeces were collected from 0 to 72 h after dosing and tissue samples were collected from animals exsanguinated at 12, 24, 48 and 72 h after dosing. The concentration of total 14C-labelled residues (14C-SDM equivalents) in tissues other than the gastrointestinal tract ranged from 99-1 ppm (plasma) to 13.8 ppm (adipose tissue) 12 h after dosing. Seventy-two hours after dosing tissue concentrations ranged from 5.4 ppm (plasma) to 0.5 ppm (skeletal muscle). The concentration in the large intestine was substantially higher (10.4 ppm) than in the stomach (2.8 ppm) and small intestine (1.4 ppm) 72 h after dosing. 2. Of the 14C, 77% was excreted in the urine from 0 to 72 h after dosing with 14C-SDM, mostly in the 0-24-h collection. Fifteen percent was excreted in the faeces from 0 to 72 h after dosing, with most of this occurring 36-72 h post-dosing. 3. 14C-SDM accounted for 24% (liver) to 66% (adipose tissue) and the N4-acetyl derivative of SDM (N4-Ac-SDM) accounted for 10% (skeletal muscle) to 35% (kidney) of the total 14C in the tissues 12 h after dosing. The N4-glucose conjugate of SDM (G-SDM) was a major 14C-labelled compound in skeletal muscle (21% of total) and liver (28%) but it was not detected in adipose tissue or kidney. The N4-glucuronic acid conjugate of SDM (GA-SDM) was a minor metabolite in kidney, but was not detected in other tissues collected 12 h after dosing. Desamino SDM was a minor metabolite in the kidney. A minor metabolite in plasma was identified as the sulphate ester of 3-hydroxysulphadimethoxine. 4. 14C-labelled fractions isolated from 0 to 6-h urine included N4-Ac-SDM (82%), SDM (3%) and GA-SDM (6%).

Evaluation of the Cd, Cu, and Zn Biosorption in Two‐Metal Systems Using an Algal Biosorbent

AbstractThe equilibrium sorption capacity of the formaldehyde‐cross‐linked brown seaweed Ascophyllum nodosum biomass was studied using two‐metal systems comprising either (Cu + Zn), (Cu + Cd), or (Zn + Cd). Three‐dimensional sorption isotherm surfaces were used in the evaluation of sorption performance, replacing simple isotherm curves. While each of the metals tested can inhibit the sorption of the others, at low total residual metal concentrations the total metal sorption uptake increases. At higher total metal concentrations, the total metal sorption uptake either remains constant, or there may be a slight decrease compared to single‐metal uptakes. This is an indication of a mutual interference in the sorption uptake of the two metals tested in each system.

A field-study of leaching and degradation of nine pesticides in a sandy soil

A field study was conducted on a coastal sandy soil (Karrakata sand) of Western Australia from July to December 1990, to measure the leaching and degradation rates of chlorpyriphos, chlorthal dimethyl, fenamiphos, linuron, metalaxyl, metribuzin, prometryne, propyzamide and simazine. Commercial grade products were sprayed in dilute solution form at recommended rates to the surface of held plots. Irrigation was applied daily which together with rainfall gave effective rainfall equivalent to at least 120% of potential evaporation. Pesticide residue concentrations in soil samples taken at 5 cm increments down to 50 cm, at different days after application, were determined by high performance liquid chromatography (HPLC). Mean leaching depths (MLDs) were calculated by weighting the percentage residues remaining at different depths in the soil profile. The MLDs for the 5 month period followed the order: chlorpyriphos and chlorthal dimethyl (<5 cm) < linuron and simazine (6) < propyzamide (8) and prometryne (9) < metribuzin (12) < metalaxyl (18) < fenamiphos and metabolites (28). This generally corresponded inversely with the sorption coefficients (K-oc). The degradation rates (i.e. decreases with time of total residue concentration in the sampled profile) could mostly be described by first-order regressions (R(2) = 0.59-0.95). Calculated half-lives showed the order: metribuzin (27 days), simazine (28) < fenamiphos (43), chlorthal dimethyl (45) < prometryne (58), propyzamide (59) < metalaxyl (70) < chlorpyriphos (81) < fenamiphos plus metabolites (98) < linuron (219). The potential for causing ground water contamination, as indicated by the ratio of half-life to Koc followed the order: chlorthal dimethyl, chlorpyriphos < metribuzin, prometryne < simazine, propyzamide < linuron < metalaxyl < fenamiphos and metabolites.

Congener-specific analysis of polychlorinated biphenyls in white-tailed sea eagles Haliaeetus albicilla collected in Poland

The concentrations of polychlorinated biphenyl (PCBs) congeners including highly toxic non-, mono-, and di-ortho coplanar members as well as their pattern were determined in breast muscles of white-tailed sea eagles collected dead between 1982 and 1990 in Poland. There was a wide variation in total PCB residue concentrations among eagles from various breeding sites, with the Baltic Sea coast registering the highest concentrations. The pattern of PCB residues differed between the eagles examined. Hexa-, hepta-, and pentachlorobiphenyls contributed between 45 and 56%, 18-and 37%, and 9 and 22% in total PCBs, respectively. Toxic equivalents (TEQs) of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for non-, mono-, and di-ortho coplanar PCBs were very high (8.0–72 μg/g wet wt) in white-tailed sea eagles from breeding sites of the coastal area of the southwestern Baltic Sea, and were relatively lower (0.69–4.0 μg/g wet wt) in other birds, including two specimens from breeding sites of inland Poland, which died because of acute lead poisoning. PCB IUPAC Nos. 118, 105, 126, and 156 were the highest contributors to the TCDD TEQ of coplanar members, occupying between 39.1 and 57.0%, 9.8 and 17.5%, 7.4 and 22.3%, and 7.0 and 14.2%, respectively. The concentrations of coplanar PCBs in adult white-tailed sea eagles were the highest ever reported in wildlife, but that of total PCBs were similar to those reported in dead eagles from the breeding sites of the coastal area of the northern Baltic in Sweden and Finland in the 1960s and 1970s.

Absorption, tissue distribution and metabolism of chlorpyrifos in channel catfish following waterborne exposure

AbstractThe pharmacokinetics, tissue distribution, and metabolism of waterborne chlorpyrifos were investigated in channel catfish (Ictalurus punctatus) fitted with arterial and urinary catheters. Pharmacokinetic analysis indicated rapid absorption of parent chlorpyrifos from water into blood and slower distribution to peripheral tissues. Total 14C residue concentrations were highest in fat and lowest in muscle. Parent chlorpyrifos comprised > 90% of the total 14C residues in the whole fish. 14C residues were excreted by renal and biliary routes as metabolites of chlorpyrifos; excretion of the parent chemical was negligible. Trichloropyridinol (TCP) was the major metabolite in blood (approximately 40% of total residues), whereas the glucuronide conjugate of TCP was the major metabolite in urine (60–90%) and bile (> 90%). The pharmacokinetics and metabolism of water‐borne chlorpyrifos in the channel catfish were similar to the disposition of chlorpyrifos in other vertebrates.

Polarographic determination of total pyrethroid residues in stored cereals

A new method for determination of the total cyanopyrethroid residue concentration in stored cereals by differential-pulse polarography is proposed. Cyanopyrethroids were previously extracted with a non-polar solvent and purified by solid-phase extraction. The total pyrethroid residue concentrations are determined by differential-pulse polarography of 3-phenoxybenzaldehyde formed quantitatively by rapid and reproducible alkaline alcoholysis of the sample. The method is linear, quantitative and reproducible for maize and wheat analysis in the range 0.1–3.0 mg kg–1. A thin-layer chromatographic method for identification of six widely used cyanopyrethroids in the sample is described. The electrodic reduction process of 3-phenoxybenzaldehyde is examined and the reduction products isolated and identified.

Polychlorinated biphenyl residues and egg mortality in double‐crested cormorants from the great lakes

AbstractWe evaluated the overall potency of polychlorinated biphenyl (PCB)‐containing extracts from double‐crested cormorant (Phalacrocorax auritis) eggs with an in vitro bioassay system, the H4IIE rat hepatoma cell bioassay. Results from the H4IIE bioassay were strongly correlated with the hatching success of eggs in the colonies, whereas conventional methods of PCB analysis correlated poorly with hatching success of eggs from the same colonies. These observations suggest that even though concentrations of total PCB residues have declined in almost all compartments of the environment, their effects are still being observed. The significance of this observation is that the adverse symptoms presently observed in certain Great Lakes fish‐eating waterbird populations do not appear to be caused by some as yet unidentified industrial chemical or chemicals and seem not to be the result of pesticides, but rather to the dioxin‐like activity of PCBs. Evidence is presented to suggest that the relative enrichment of the potency of PCBs in the environment may play a role in the persistence of the observed adverse symptoms.

Self-Cycling Fermentation Applied to Acinetobacter calcoaceticus RAG-1

The self-cycling fermentation (SCF) technique was applied to a culture of Acinetobacter calcoaceticus RAG-1. This method was shown to result in synchronization of the cells, achieving a 77% improvement in cell synchrony over that of the batch case. Cellular occurrences, averaged out by asynchronous batch cultures, were magnified by the temporal alignment of metabolic events brought about by the synchronization associated with SCFs. The cell population doubled only once per cycle, thus establishing an equality between cycle time and doubling time. Parameters of interest were biomass concentration, total bioemulsifier (emulsan) production, cycle time, and residual carbon concentration. Cycle-to-cycle variation of these parameters was, in most cases, insignificant. Repeatability of doubling time estimates (based on 95% confidence intervals) was roughly 7 to 10 times better between cycles in an SCF than between batch replicates. The carbon substrate was completely utilized in all cases in which it was measured, giving this technique an advantage over chemostat-type fermentations. The dissolved-oxygen profiles monitored throughout a cycle were found to be repeatable. A characteristic shape, which can be related to the growth of the organism, was associated with each carbon source. The specific emulsan productivity of SCFs was found to be approximately 50 times greater than that of the batch process and 2 to 9 times greater than that of the chemostat, depending on the dilution rate considered. With respect to specific emulsan production, a 25-fold improvement over that in an immobilized cell system recently introduced was obtained. Thus, SCFs are a viable alternative to established fermentation techniques.

Using Reducing Agents to Eliminate Chlorine Dioxide and Chlorite Ion Residuals in Drinking Water

In an effort to determine the viability of various disinfection alternatives, the Evansville, Ind., Water and Sewer Utility is engaged in a pilot‐plant investigation to compare chlorine dioxide and ozone pretreatment. As a result of increased speculation that the total residual concentration of chlorine dioxide and its inorganic species will soon be regulated, supplemental studies were performed to determine the effectiveness of various reducing agents for reducing or eliminating chlorine dioxide and chlorite ion residuals in finished water. The effectiveness of ferrous iron in achieving the desired reductions is examined along with promising results obtained with sodium thiosulfate. Specific difficulties encountered with the sulfur dioxide–sulfite ion method of chlorite ion reduction are also presented.

Accumulation of DDT Residues in the Testes of Channa punctatus (Bloch): A Gas Liquid Chromatographic Analysis

Residues of DDT isomers accumulated in the testes of Channa punctatus (BLOCH) were quantitatively estimated by exposing the fish to 2.5 ppm sublethal concentration for 32 days. The study revealed a high accumulation of DDT residues in the testes. The maximum concentration of residues was noted on the 32nd day of the experiment. The DDT isomer accumulated in maximum concentrations was followed by DDE and DDD isomers. The maximum residue concentrations were 0.3221 ppm (DDT), 0.1119 ppm (DDE) and 0.0695 ppm (DDD) on the 32nd day of the experiment. The total DDT residue concentration at the final interval was 0.563 ppm.

Organophosphorus insecticide residues in virgin Greek olive oil, 1988–1990

AbstractOrganophosphorus insecticide residues have been monitored for two years in virgin olive oil after dimethoate and fenthion treatments to control the olive fruit fly. No dimethoate residues were detected in any of the samples. For the first and second years, 50% and 21%, respectively, of the samples contained no detectable fenthion residues, while 4% and 6%, respectively had residue concentrations exceeding the Codex Alimentarious Maximum Residue Limit (1 mg kg−1). The mean concentration was 0·236 mg kg−1 oil and the estimated daily intake of fenthion 0·0002 mg kg−1 body weight (Acceptable Daily Intake 0·001 mg kg−1 body weight). The parent compound was the most important residue in fresh samples, while aged samples contained a higher amount of the metabolite fenthion sulfoxide. The contribution of the oxygen analogues (P= 0 metabolites) of fenthion to the total residue concentration was<5% in most cases.

Residues of endosulfan in the livers of wild catfish from a cotton growing area

Residues of endosulfan insecticide (α-and β-isomers, and endosulfan sulphate) were determined in the livers of catfish from a cotton growing area during the summer and winter of 1988. The concentration of total endosulfan residues found in the fish was up to 0.31 mg kg(-1) wet wt. It decreased in winter with a maximum 0.02 mg kg(-1) wet wt. The difference in endosulfan residues between seasons was statistically significant (ANOVA,p<0.01).