Ion chromatographic determination of bromate in drinking water by post-column reaction with fuchsin.

Bromate deriving from ozonation treatment of bromide containing waters are analyzed by ion-exchange chromatography with spectrophotometric detection after post-column reaction with fuchsin in low pH medium. An anion-exchange column was used with 2.7 mM carbonate-0.3 mM hydrogencarbonate eluent. The eluent from the column was then allowed to react with a SO2-reduced fuchsin solution and then with a diluted HCl solution at 65 degrees C. The developed colour of the final product was measured spectrophotometrically at 530 nm. Linearity was checked up to 50 micrograms/l with a 200-microliter injection loop (r2 = 0.9997) and up to 100 micrograms/l of bromate with 100 microliters loop (r2 = 0.9939). Nitrate, sulfate, bromide, phosphate, fluoride did not interfere at 100 mg/l concentration level; only nitrite at concentration levels greater than 3 mg/l caused partial overlapping with bromate peak, but this value is not likely to occur in common drinking water. The detection limit (3 sigma) is 0.1 microgram/l (1 microgram/l propagation error approach).     

Determination of urinary t-t muconic acid as biomarker of environmental benzene intake and its interference factors

The target of our study was the determination of urinary t,t muconic acid concentration, as a biomarker of benzene intake in a population. Urinary samples of 101 subjects, males and females were obtained to whom. Information regarding modification and confounding factors were recorded by questionnaire. The samples were analysed by HPLC, after extraction of trans,trans muconic acid on strong anionic exchange cartridges. In these analytical conditions the detection limit with good care is 10 micrograms/l. A concentration range from 10 to 1300 micrograms/l was found. High levels found in the population could explained by confounding factors present. The obtained results were correlated with sex, age and smoking or non smoking. There was a significant difference in mean concentrations between heavy smokers (160 micrograms/l) and non smokers (110 micrograms/l), that showed tobacco as an interference factor. The study showed that it is strictly necessary carry out a thorough anamnesis before sampling with the objective of finding eventual interference factors such as smoking, diet and drugs taken.     

Melt polycondensation approach for reduction degradable helical polyester based on l‐cystine

Melt polycondensation approach is developed for new classes of reduction responsive disulfide containing functional polyesters based on l ‐cystine amino acid resources under solvent free process. l ‐Cystine was converted into multi‐functional ester‐urethane monomer and subjected to thermoselective transesterification at 120 °C with commercial diols in the presence of Ti(OBu)₄ to produce polyesters with urethane side chains. The polymers were produced in moderate to high molecular weights and the polymers were found to be thermally stable up to 250 °C. The β‐sheet hydrogen bonding interaction among the side chain urethane unit facilitated the self‐assembly of the polyester into amyloid‐like fibrils. The deprotection of urethane unit into amine functionality modified the polymers into water soluble cationic polyester spherical nanoparticles. The reduction degradation of disulfide bond was studied using DTT as a reducing agent and the high molecular weight polymers chains were found be chopped into low molecular weight oligomers. The cytotoxicity of cationic disulfide nanoparticle was studied in MCF‐7 cells and they were found to be biocompatible and non‐toxic to cells upto 50 μg/mL. The custom designed reduction degradable and highly biocompatible disulfide polyesters from l ‐cystine are useful for futuristic biomedical applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2864–2875     

Determination of beta-19-nortestosterone and its metabolite alpha-19-nortestosterone in biological samples at the sub parts per billion level by high-performance liquid chromatography with on-line immunoaffinity sample pretreatment

An immunoaffinity precolumn (immuno precolumn) packed with Sepharose-immobilized polyclonal antibodies against the anabolic hormone 17 beta-19-nortestosterone (beta-19-NT) was used for the selective on-line pretreatment of raw extracts of urine, bile and tissue samples by high-performance liquid chromatography. Using UV detection (247 nm), beta-19-NT and its metabolite 17 alpha-19-nortestosterone (alpha-19-NT) can be determined in biological samples with a detection limit of 0.05 microgram/kg. Owing to the high clean-up efficiency of the immuno precolumn and the large sample volumes used, confirmation by gas chromatography-mass spectrometry is possible at this level. In urine samples from a calf treated with 19-nortestosterone 17 beta-laurate, the maximum concentrations of beta-19-NT (1.3 micrograms/l) and alpha-19-NT (3.1 micrograms/l) were found seven days after intramuscular administration. In a bile sample from this calf only alpha-19-NT (55 microgram/l) was detected. In meat samples from three treated calves, the concentration of beta-19-NT varied from 0.1 to 1.6 micrograms/kg and no alpha-19-NT could be detected. In liver samples from these calves, the concentrations of beta-19-NT and alpha-19-NT were less than 0.05-0.1 and 0.5-0.9 micrograms/kg, respectively. In the corresponding kidney samples, the concentrations of beta-19-NT and alpha-19-NT were 0.4-0.5 and 0.5-1.6 micrograms/kg, respectively. The application of the same immuno precolumn to the determination of 17 beta- and 17 alpha-trenbolone, two structurally related steroids, is also demonstrated.     

Application of a contactless conductometric detector for the simultaneous determination of small anions and cations by capillary electrophoresis with dual-opposite end injection

A contactless conductometric detection (CCD) system for capillary electrophoresis (CE) with a flexible detection cell was applied for the simultaneous determination of small anions and/or cations in rain, surface and drainage water samples. The applied frequency, the amplitude of the input signal, the electrolyte conductivity and electrode distance were found to be the most significant factors affecting the detection sensitivity. 2-(N-Morpholino)ethanesulfonic acid/histidine-based (MES/His) electrolytes were used for direct conductivity detection of anions and cations, while ammonium acetate was selected for indirect conductivity determination of alkylammonium salts. For the simultaneous separation procedure, involving dual-opposite end injection, an electrolyte consisting of 20 mM MES/His, 1.5 mM 18-crown-6 and 20 microM cetyltrimethylammonium bromide provided baseline separation of 13 anions and cations in less than 6 min. The detection limits achieved were 7-30 micrograms/l for direct conductometric detection of various common inorganic cations and anions, excluding F- (62 micrograms/l) and H2PO4- (250 micrograms/l), and 35-178 micrograms/l for indirect conductometric detection of alkyl ammonium cations. The developed electrophoretic method with conductometric detection was compared to ion chromatography.     

Determination of hexahydrophthalic anhydride in air using gas chromatography.

Two methods for the determination of hexahydrophthalic anhydride (HHPA) in air were developed. In a solid sorbent method, HHPA was sampled in Amberlite XAD-2 tubes, eluted in toluene and analysed by gas chromatography with flame ionization detection. The sampling rates were 0.2 and 1.0 l/min. At 15 micrograms/m3 (relative humidity less than 2%) and 27 micrograms/m3 (relative humidity 70%) no breakthrough was observed. However, at 160 micrograms/m3 (relative humidity less than 2%), 6% breakthrough was found. The sampling efficiency of the sampling rates 0.2 and 1.0 l/min did not differ. In a bubbler method, HHPA was sampled in bubblers filled with 0.1 M sodium hydroxide solution. The sodium salt of hexahydrophthalic acid was formed. No breakthrough was observed using a sampling rate of 1.0 l/min. The samples were stable during storage for eight weeks in a refrigerator. The HHP acid was esterified with methanol-boron trifluoride and analysed by gas chromatography-flame ionization detection. Apparatus for the generation of standard atmospheres of HHPA, in the range of 10-3000 micrograms/m3, was developed using the diffusion principle. For the solid sorbent method the precision (coefficient of variation) of the overall method was 2-7%, and for the bubbler method 3-19% (range 15-160 micrograms HHPA/m3; relative humidity = less than 2-70%). A comparison between the two methods was performed using the standard atmosphere. The concentrations found by the solid sorbent method were 86-98% of those found by the bubbler method (range 15-160 micrograms HHPA per m3; relative humidity = less than 2-70%). In work environment air, 93% was found using the solid sorbent method relative to the bubbler method at a mean concentration of 330 micrograms/m3 (coefficient of variation = 39%; range 200-540 micrograms/m3). For both methods, concentrations greater than 3 micrograms/m3 could be quantified at 60 min sampling with a sampling rate of 1.0 l/min.     

Capillary electrophoretic determination of inorganic anions in the drainage and surface water samples.

Capillary electrophoresis was used for separation and quantitation of several inorganic anions in the drainage and surface water samples from the region with extensive use of fertilisers. Baseline separation of 13 small anions including nitrite and nitrate up to the concentrations of 100 mg/l was achieved in less than 5 min. The electrolyte consisted of 3 mM K2CrO4, 30 microM cetyltrimethylammonium bromide and 3 mM boric acid at pH 8. The method yielded precisions of 1.8-7.2% (RSD, n = 10) and detection limits from 4 micrograms/l (Cl-) up to 500 micrograms/l (citrate). The results of the CE method were compared to ion chromatography using water-acetonitrile (86:14) at pH 8.6 adjusted with NaOH as the mobile phase and consistent results were obtained.     

Determination of bromide ion in raw and drinking waters by capillary zone electrophoresis.

A new capillary zone electrophoretic method was developed for the determination of bromide ion in raw and drinking waters. An NaCl-based low-pH buffer caused a reduction of electroosmotic flow (EOF) in the buffer zone, whereas injected water sample resulted in higher EOF in the sample zone thus pumping out the neutral water plug. Sample stacking was used for the preconcentration. The method was applicable for waters from low to intermediate ionic strengths, i.e., the concentration of chloride should preferably be less than 40 mg/l. The method had a limit of detection of 15 micrograms/l at a signal-to-noise ratio of three (S/N = 3) and a limit of quantitation of 20 micrograms/l. CZE results obtained with real samples were compared with ion chromatography--inductively coupled mass spectrometric results.     

Characterization and determination of organic compounds in the mutagenic XAD-2 extracts of drinking water.

Amberlite XAD-2 extracts, which exhibit mutagenicity in the Ames assays, of drinking water sampled each month during the period from April 1988 to March 1989 were studied in order to characterize and determine the organic pollutants. The major organic pollutants were phthalate ester plasticizers such as dibutyl and di(2-ethylhexyl) phthalate. Several polynuclear aromatic hydrocarbons (PAHs) and the organocholorine pesticide oxadiazon were also identified to be present at low concentrations. The XAD-extractable and chromatographable organic pollutants were found to be composed of PAHs with a mean concentration of 0.136 micrograms/l(ca. 10% of the total amount of organic compounds detected), phthalates with a mean value of 0.405 micrograms/l(ca. 30%) and other compounds with a mean value of 0.845 micrograms/l(ca. 60%). The concentrations and compositions of these organic pollutants were correlated with the effective rainfall content of the river and with the water temperature.     

Trace analysis of airborne 1,6-hexamethylenediisocyanate and the related aminoisocyanate and diamine by glass capillary gas chromatography

A capillary gas chromatographic method was developed for the analysis of complex air mixtures of 1,6-hexamethylenediisocyanate, 1,6-hexamethyleneaminoisocyanate and 1,6-hexamethylenediamine. The method is based on derivatization in the sampling step of the reactive isocyanate groups to corresponding urethane groups by the alkaline ethanolic solvent and a subsequent derivatization of remaining amino groups to amide groups with heptafluorobutyric acid anhydride. The overall procedure, including sampling, gave a linear response at air concentrations of 3-300 micrograms/m3 for 1,6-hexamethylenediisocyanate with a precision of ca. 4% at 15 micrograms/m3 and a detection limit of ca. 0.2 microgram/m3 using nitrogen selective detection. In a field measurement of air concentrations in welding work on lacquered metal parts at a motor-car workshop, concentrations of 1,6-hexamethylenediisocyanate above 600 micrograms/m3 were found. Also 1,6-hexamethyleneaminoisocyanate and 1,6-hexamethylenediamine were found at concentrations of the order of 15% of the 1,6-hexamethylenediisocyanate concentration.     

Determination of mefloquine by electron-capture gas chromatography after phosgene derivatization in biological samples and in capillary blood collected on filter paper

Mefloquine is determined in 100-microliter samples of whole blood, plasma and capillary blood collected on filter paper by gas chromatography with electron-capture detection after derivatization with phosgene. Sample preparation for whole blood and plasma involves a protein precipitation step that uses a combination of zinc and acetonitrile, followed by simultaneous extraction with methylene chloride and derivatization with phosgene at pH 9.50. Filter paper spots are immersed for 12-24 h in 0.1 M hydrochloric acid, followed by simultaneous extraction with methyl tert.-butyl ether and derivatization. After evaporation of the organic phase and reconstitution with ethyl acetate, 1 microliter of the extract is injected into a megabore capillary column. Because of the high sensitivity of the method, mefloquine concentrations down to 25 nmol/l (9.5 micrograms/l) are determined in 100-microliters samples with a relative standard deviation of 12% at the 25 nmol/l level. Excellent precision was obtained over the range of concentrations tested, 0.10-3 mumol/l (45-1100 micrograms/l), in both plasma and whole blood and from filter-paper-collected capillary blood. The day-to-day relative standard deviation in plasma at the therapeutic level (1-3 mumol/l) was 4.5% (n = 8).     

Chromatographic determination of amines in biological fluids with special reference to the biological monitoring of isocyanates and amines. IV. Determination of 1,6-hexamethylenediamine in human urine using capillary gas chromatography and selective ion monitoring

A capillary gas chromatographic (GC) method was developed for the determination of 1,6-hexamethylenediamine (HDA) in hydrolysed human urine. The method was based on a derivatization procedure with heptafluorobutyric anhydride. The amides formed were determined using capillary GC with selected ion monitoring in the chemical ionization mode with ammonia as reagent gas. The overall recovery was 34% for a concentration of 100 micrograms/l of HDA in urine. The minimum detectable concentration in urine was below 0.5 microgram/l. The precision of the method was 5% (n = 9). Deuterium-labelled HDA [H2NC2H2(CH2)4C2H2NH2] was used as the internal standard. A male subject was exposed to hexamethylene diisocyanate (HDI) for 7.5 h in a test chamber. The average air concentration of HDI was ca. 30 micrograms/m3, which corresponds to ca. 85% of the threshold limit value in Sweden (35 micrograms/m3). The half time of urinary levels of HDA was ca. 1.4 h and more than 90% of the urinary elimination was completed within 4 h after the exposure. The amount of HDA excreted in urine was ca. 10 micrograms, corresponding to ca. 10% of the estimated inhaled dose of HDI.     

Antibacterial activity of a new tetracyclic quinolone, No. 5290, against norfloxacin- and ciprofloxacin-resistant strains of Staphylococcus aureus.

The antibacterial activity of a new tetracyclic quinolone, No. 5290, against 25 strains of Staphylococcus aureus clinically isolated in Japan in 1988-1989 was determined. The minimum inhibitory concentrations (MICs) of No. 5290 against both quinolone-susceptible (MIC: norfloxacin less than or equal to 6.25 micrograms/ml, ciprofloxacin less than or equal to 1.56 micrograms/ml) and 4 out of 5 norfloxacin- and ciprofloxacin-moderately resistant strains (MIC: 25 micrograms/ml less than or equal to norfloxacin less than or equal to 50 micrograms/ml, 3.13 micrograms/ml less than or equal to ciprofloxacin less than or equal to 12.5 micrograms/ml) were 0.05 micrograms/ml. Similar findings were obtained on the quinolone-resistant mutants derived by norfloxacin- or KB-5246-selection from quinolone-susceptible clinical isolates of S. aureus. The uptake of No. 5290 into a quinolone-susceptible strain of S. aureus was 2.47 micrograms/mg dry cell and the uptake in norfloxacin- and ciprofloxacin-moderately resistant strains was comparable to that in the quinolone-susceptible strain. The uptake of No. 5290 in both the quinolone-susceptible strain, and norfloxacin- and ciprofloxacin-moderately resistant, and No. 5290-susceptible strains was only slightly influenced by the treatment of bacteria with carbonyl cyanide m-chlorophenylhydrazone. These findings indicate that: (i) No. 5290 has potent antibacterial activity against quinolone-susceptible strains of S. aureus, and the potent activity might be due to a high uptake caused by an ineffective efflux of No. 5290. (ii) No. 5290 also has potent antibacterial activity against norfloxacin- and ciprofloxacin-moderately resistant strains, the reason for which could not be explained by the efflux.     

Flow-injection chemiluminometric determination of some thioxanthene derivatives in pharmaceutical formulations and biological fluids using the [Ru(dipy)3(2+)]-Ce(IV) system.

A flow-injection (FI) methodology using tris(2,2'-dipyridyl)ruthenium(II), [Ru(dipy)3(2+)], chemiluminescence (CL) was developed for the rapid and sensitive determination of three thioxanthene derivatives, namely zuclopenthixol hydrochloride, flupentixol hydrochloride and thiothixene. The method is based on the CL reaction of the studied thioxanthenes with [Ru(dipy)3(2+)] and Ce(IV) in a sulfuric acid medium. Under the optimum conditions, calibration graphs were obtained over the concentration ranges 0.002-6 migrograms/ml for zuclopenthixol hydrochloride, 0.5-15 micrograms/ml for flupentixol hydrochloride and 0.05-7.5 micrograms/ml for thiothixene. The limits of detection (s/n = 3) were 4.2 x 10(-9) mol/l zuclopenthixol hydrochloride, 2 x 10(-8) mol/l flupentixol hydrochloride and 4.5 x 10(-8) mol/l thiothixene. The method was successfully applied to the determination of these compounds in dosage forms and biological fluids.     

Effective monitoring of residues of nortestosterone and its major metabolite in bovine urine and bile

The results of a newly developed method for the detection and identification of residues of nortestosterone (NT) and one of its major metabolites, 17 alpha-nortestosterone (epiNT) are described. The method is based on sample clean-up by immunoaffinity chromatography and detection by high-performance liquid chromatography and/or gas chromatography-mass spectrometry (selected-ion monitoring). All samples of bile from calves that had been treated with NT contained significant amounts of epiNT (6-18 micrograms/l). The NT content of these samples, if detectable, was below 1 microgram/l. Urine contained, with one exception, less than 1 microgram/l epiNT. NT itself if detectable, was, present in urine or bile at levels below 0.1 microgram/l. The results corresponds well with results obtained with a radioimmunoassay procedure.     

Urethane-hydrolyzing enzyme from Citrobacter sp

Urethane, a cancer-causing chemical, was reported to contaminate alcoholic beverages such as whisky, liquor, wine and sake. Enzymatic removal of urethane would be a possible approach to remove this potentially hazardous chemical from alcoholic beverages. We found that Citrobacter sp. isolated from mouse feces stoichiometrically decomposed urethane to ethanol and ammonia. We named this enzyme "urethanase." Partially purified urethanase could hydrolyze several carbamates and some amides. However, urea, N-alkyl ureas and ethyl esters of organic acids were not hydrolyzed at all. These results suggest that urethanase belongs to the category of amidase. The enzyme was inactive in high concentrations of alcohol and at acidic pH and was practically ineffective for the elimination of urethane from alcoholic beverages.     

Biobased polyurethanes from polyether polyols obtained by ionic‐coordinative polymerization of epoxidized methyl oleate

A series of poly(ether urethane) networks were synthesized from polyether polyols obtained by ionic‐coordinative polymerization of epoxidized methyl oleate (EMO) using 4,4′‐methylenebis(phenyl isocyanate) or l ‐lysine diisocyanate as coupling agents. Moreover, a variety of segmented poly(ether urethane) networks with different hard segment contents were obtained using 1,3‐propanediol as the chain extender. The materials were characterized by differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical thermal analysis, and tensile properties. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Modification of a Dionex System 12 ion chromatograph for sequential determination of the main components in atmospheric precipitation

A modification of a Dionex System 12 ion chromatograph is described which enables organic anions (acetate and formate), inorganic cations (ammonium, sodium and potassium) and inorganic anions (chloride, nitrate and sulphate) to be determined sequentially in one measuring procedure. The modified instrument consists of a programmable controller unit, a conductimetric meter, two conductimetric detectors of the Dionex System 12 ion chromatograph, the HPIC-AS4A and HPIC-CS3 modern separation units, AMMS-1 and CMMS-1 micro-membrane suppressor columns, a unique system of valves from Dionex and two dual pumps from Biotronik. The limits of detection are between about 1 and 3 micrograms/l for chloride, nitrate and sulphate and between about 2 and 10 micrograms/l for acetate, formate, ammonium, sodium and potassium. The reliability of the method was demonstrated by analysing two NBS simulated rain water Standard Reference Materials. Some examples are given of the application of the method to the sequential determination of the main precipitation components in typical samples from urban and rural regions of the F.R.G. The ion concentrations varied between about 0.02 and 300 mg/l.     

High-performance liquid chromatographic determination of 4,4'-methylenedianiline in human urine

A method is described for the determination of urinary 4,4'-methylenedianiline (MDA) by high-performance liquid chromatography (HPLC). MDA was extracted from hydrolyzed urine using C18 solid-phase extraction columns. The extract was analyzed by reversed-phase HPLC with electrochemical detection at a cell potential of 0.8 V. The method was very sensitive (detection limit 2.5 micrograms/l) and quantitation using 4,4'-ethylenedianiline as an internal standard correlated well with results by gas chromatography-mas spectrometry. Run-to-run precision (n = 25) averaged 8.9%. In analysis of more than 160 potentially exposed workers, MDA was detected in less than 20% of the urines and concentrations ranged up to 210 micrograms MDA per g of creatinine.     

气相色谱/质谱法测定大鼠脑中5-羟色胺的含量

采用气相色谱／质谱法（ＧＣ／ＭＳ）测定了正常大鼠和服药大鼠脑组织中５－羟色胺（５－ＨＴ）的浓度。大鼠脑组织制成匀浆后,先将５－ＨＴ酰化,酰化物经乙酸乙酯提取后,再经七氟丁酸酐衍生化,用ＧＣ／ＭＳ测定。ＭＳ采用电子捕获负离子化学电离（ＥＣＮＩＣＩ）模式。方法的线性范围为０．５０～５０．０μｇ／Ｌ,回归方程为Ｙ＝０．１３４８Ｘ－０．０７９９５（ｒ＝０．９９９６）;平均回收率为９８．２％±３．８％（ｎ＝１０）;检测限为０．５μｇ／Ｌ;相对标准偏差小于１０％。