A biosensor for determination of the circulating biomarker CA125/MUC16 by Surface Plasmon Resonance Imaging.

CA125/MUC16 is an ovarian tumor cell marker widely used as a biomarker in epithelial ovarian carcinoma. CA125/MUC16 is also used for evaluation of the ROMA (Risk of Ovarian Malignancy Algorithm) value. In this work, a Surface Plasmon Resonance Imaging (SPRI) biosensor for circulating CA125/MUC16 has been developed. The anti-MUC16 antibody was attached to a gold chip via a cysteamine linker. The EDS/NHS protocol was used for the covalent attachment of the antibody. The developed biosensor is specific for CA125/MUC16, and exhibits good recovery and acceptable precision. Its linear response range (2.2-150 U/ml) is well suited to determination of the marker in the blood serum of a healthy control group and, after appropriate dilution, of patients with ovarian cancer. CA125/MUC16 was determined in two series of real samples: blood serum from patients with ovarian cancer and endometrial cysts. The method was validated by parallel determination of the samples using the chemiluminescent Architect i2000 method.

Determination of collagen type IV by Surface Plasmon Resonance Imaging using a specific biosensor.

Serum collagen type IV (COLIV) is a promising tumor marker. High COLIV concentrations have been found in the serum of patients with colorectal, gastric, lung, liver and breast cancers. The aim of this work was to develop a biosensor for use with the Surface Plasmon Resonance Imaging (SPRI) technique for COLIV determination. The biosensor consists of glass covered with gold and immobilized monoclonal mouse anti-human collagen type IV antibody via cysteamine linker. The biosensor works selectively within a dynamic response range between 10 and 300 ng mL-1, with LOD 2.4 ng mL-1 and LOQ 8 ng mL-1. The precision of determination is 4.7% at a 150 ng mL-1 COLIV spike and 8.0% at a 20 ng mL-1 spike, with recoveries of 101% and 106% respectively. A 100-fold excess of collagen I, albumin, laminin and fibronectin is tolerated. The average COLIV blood plasma concentration of healthy donors determined by the developed method was 69 ± 10 ng mL-1, while the median of six results available in the literature was approximately 80 ng mL-1. The average COLIV blood plasma concentration of breast cancer patients was 360 ± 68 ng mL-1, showing the high potential of COLIV as a marker of this type of cancer.

Determination of short-chained poly(ethylene glycols) and ethylene glycol in environmental samples.

A method for the determination of ethylene glycol (EG), di(ethylene glycol) (E2) and tri(ethylene glycol) (E3) in environmental samples (raw and treated sewage, river water) has been developed. These substances are important by-products in the biotransformation of non-ionic surfactants (NS). The method is based on sequential liquid-liquid extraction with ethyl acetate and chloroform (resulting in the separation of poly(ethylene glycols) (PEG) and EG from the water matrix), precipitation of long-chained PEG (PEGlch) with Dragendorff reagent, extraction of short-chained PEG (PEGsh) (EG, E2 and E3) from a filtrate with chloroform and the final determination using alternating current voltammetry. The precision of the method is 7.3%, the recovery 95% and a detection limit of 1.5 microg in the sample, i.e. 10 microg l(-1) was achieved. As evidenced by F and t tests, the developed method is equivalent to the indirect PEGsh determination by the difference approach where concentration of PEGsh is determined by the difference of the total PEG and PEGlch. The PEGsh fraction was found to be present in considerable concentrations in raw and treated sewage, river water, as well as being a major biotransformation by-product in the continuous flow activated sludge testing of fatty alcohol ethoxylates.

Separation of poly(ethylene glycols) into fractions by sequential liquid-liquid extraction.

Poly(ethylene glycols) (PEG) are the major metabolites of non-ionic surfactants (NS). Chains of PEG may be shortened due to further biodegradation. The separate determination of short- and long-chained PEG (SC- and LC-PEG) may be useful to control the biodegradation of NS and PEG. A scheme for the separation of a whole mixture of PEG into SC- and LC-fractions and their subsequent determination is developed. A sequential extraction of a water sample with n-hexane and ethyl acetate is used to separate NS and other interferents as well as dichloromethane and chloroform for the separation of PEG into LC- and SC-fractions. The indirect tensammetric technique (ITT) is used for the final quantification of PEG into separated fractions as well as for the control of every separation step. The boundary between fractions is not sharp due to the similarity of the properties of neighbouring homologues which may be approximately 15 oxyethylene subunits. The developed scheme is successfully used for the separation into fractions of PEG from river water and raw and treated sewage. An initial separation of PEG from these samples by extraction with chloroform is carried out.

Tensammetric determination of non-ionic surfactants combined with the BiAS separation procedure Part 3. Determination in the presence of hydrocarbons.

A method for the determination of non-ionic surfactants (NS) in the presence of an excess of hydrocarbons is developed. The modified BiAS procedure combined with the indirect tensammetric method (BiAS-ITM) is applied for this purpose. The method consists of extraction of NS into ethyl acetate, precipitation of ethoxylates with modified Dragendorff reagent, removal of adsorbed hydrocarbons by washing with isooctane and the determination of NS in the dissolved precipitate by the ITM. The method is characterised by 96-100% recovery and RSD of 0.02-0.04 at a 1000-fold excess of hydrocarbons. The detection limit of the procedure is 1.5 mug and the linear dynamic range is 2-20 mug in the sample, which facilitates work within the range of 2-1000 mug through the use of aliquots. The non-modified version of the BiAS-ITM exhibits a loss of NS due to their extraction by droplets of residual hydrocarbons trapped in the precipitate. Isooctane as a washing agent is found to be the best among eight tested media: methanol, ethyl acetate, diisopropyl ether, chloroform, water, glacial acetic acid, benzene and isooctane.

Tensammetric determination of non-ionic surfactants combined with BiAS separation procedure (Wickbold) 2. Optimisation of the precipitation and investigation of interferences.

The precipitation step in the developed procedure (BiAS-ITM) was optimised with the aim of achieving a lower detection limit. Losses during filtration using Triton X-100 as representative non-ionic surfactant (NS), the indirect tensammetric method (ITM) and adsorptive stripping tensammetry (AdST) for the determination of the concentration of the surfactant in the precipitate and in the filtrate were investigated. The G4 glass filter recommended up to now was found to be insufficiently effective and a source of loss. The new version of the procedure developed works within the range 2-1000 mug of NS in the sample, and thus two orders of magnitude lower than the former version of the procedure, showing satisfactory recovery and precision. The detection limit (3 x S.D.) was found to be below 1.5 mug in the sample. Interferences of anionic surfactants (ASs) e.g. sodium dodecylbenzenesulphonate and sodium lauryl sulphate, lipids, e.g. glycerol trioleate (GTO), and chlorophyll were investigated. GTO and AS show no effect on the BiAS-ITM results although strong adsorption of ASs on the glass filter as well as a slight adsorption on the precipitate was found. Chlorophyll does not interfere with the determination up to 30 mug in the sample, whereas higher concentrations produce results that are too high.

Tensammetric determination of non-ionic surfactants combined with BiAS separation procedure (wickbold)-I. precipitation of different ethoxylates with modified Dragendorff reagent in the proposed and classical BiAS procedures.

The proposed procedure (BiAS-ITM) combines BiAS separation scheme of non-ionic surfactants with their determination by indirect tensammetric method (ITM). The method is based on (i) gas stripping separation of ethoxylates, (ii) their precipitation with modified Dragendorff reagent and (iii) determination of their concentration in the dissolved precipitate using ITM. Washing of the precipitate with glacial acetic acid, necessary in classical BiAS procedure which is a source of serious error, is omitted in the proposed separation scheme. The presented method determines the non-ionic surfactants instead of bismuth in the classical BiAS. The precipitation of 12 oxyethylated alcohols, four oxyethylated alkylphenols and four other ethoxylates were investigated according to the proposed procedure. Adsorptive stripping tensammery (AdST) was applied for additional control of investigated surfactants in the precipitate and in the filtrate. Simultaneously 13 ethoxylates were precipitated and determined according to classical BiAS procedure. The BiAS-ITM procedure shows significantly better recoveries and lower sensitivities vs. the chemical structure of the determined surfactants and thus BiAS-ITM is less sensitive to the composition of determined mixture than classical BiAS procedure. It enables the determination of ethoxylates having three or more oxyethylene subunits, while classical BiAS determines only those having five or more.

Determination of thallium in soils by flow-injection-differential pulse anodic stripping voltammetry.

A relatively simple and quick method for the determination of thallium in soils is described. The method does not require any separation prior to determination. Total decomposition of the sample was performed in a teflon bomb. The interferences of iron, aluminum and manganese were removed by media exchange performed in a flow-injection measuring system, and the other interferences were removed by the use of the base electrolyte consisting of 0.15M EDTA and 0.1M ascorbic acid. The contents of thallium in the examined samples of soil were between 100 and 350 ppb.

[Azoles. 27. Nitroimidazole derivatives, their antibacterial and fungicidal activity and electron affinity]. / Azole. 27. Mitteilung5: Uber Nitroimidazolderivate, ihre antibakterielle und fungizide Wirkung und Elektronen-affinität.

Nitroimidazole derivatives 3a-3g, 4a-4g and 5-8 were synthesized by treating 4,5-dinitro- and 2-methyl-4,5-dinitroimidazole (1,2) with phenacyl bromide, its p-substituted derivatives or epichlorohydrin. 1-(3-Chloro-2-hydroxypropyl)-4,5-dinitroimidazole (5) and its 2-methyl derivative 6 have been converted to imidazo-oxazoles 7 and 8 or amino imidazole derivatives 9-14 by the action of potassium carbonate or cyclic amines (pyrrolidine, piperidine, morpholine and N-methylpiperazine). Some of the newly synthesized nitroimidazole derivatives show antibacterial and fungicidal activity. The electron affinity of the nitroimidazole derivatives 1-24 is discussed on the basis of their half-wave potentials and in the connection with their eventual radiosensitizing properties.

Electrochemical masking for removal of the titanium matrix effect in DPASV determination of thallium.

The possibilities for eliminating the matrix effect caused by large concentrations of titanium in an EDTA-based electrolyte have been examined. In these solutions titanium gives a DPASV peak, the height of which decreases with increase in preconcentration time. This effect depends on the pH and is probably caused by impurities in the EDTA. Complete damping of the titanium peak by means of this effect is not possible. The influence of the following surfactants on the DPASV peak for titanium in 0.2M EDTA at pH 4.5 was investigated: polyoxyethylated alkylphenols having an average of 3 and 9.5 ethylene oxide sub-units; polyoxyethylene alcohols having an average of 5 and 20 ethylene oxide sub-units; polyoxyethylene (glycerol mono-oleate) ether having an average of 20 ethylene oxide sub-units; polyoxyethylene (sorbitol mono-oleate) ether having an average of 20 ethylene oxide sub-units; poly(ethylene oxide) having M.W. 5.0 x 10(6); poly(ethylene oxide)poly(propylene oxide) block copolymer having M.W. 1.625 x 10(4); N,N,N,N',N',N'-hexamethylhexamethylenediammonium bromide (HMB); benzyl(diisobutylphenoxyethoxy) dimethylammonium chloride; hexadecyltrimethylammonium bromide; tetrabutylammonium chloride (TBAC); hexadecyldimethylbenzylammonium chloride, hexadecyltributylphosphonium bromide; tetraphenylphosphonium bromide; sodium dodecylsulphate; sodium stearate; sodium dodecylbenzenesulphonate; sodium octadecyloxyethylene ether sulphate; sodium octadecyloxyethylene ether malonate (Malester). Except for TBAC and HMB all the surfactants investigated decreased the titanium peak, although to different degrees. Generally the effect increased in the sequence cationic surfactants < non-ionic surfactants < anionic surfactants. The more hydrophobic non-ionic surfactants decreased the titanium peak more strongly than did the less hydrophobic ones. Malester was found the best of the investigated surfactants for this purpose. Sodium dodecylbenzenesulphonate also gave good results, although in this case an additional peak appeared. In the presence of these last two surfactants iron(III) does not substantially disturb the base-line current.

Electrochemical masking of large amounts of copper in dpasv and the determination of thallium in the presence of a large excess of copper.

The influence of the following surfactants on the peak of copper in 0.2M EDTA at pH 4.5 was investigated: polyoxyethylated alkylphenols having an average of 3 and 9.5 ethylene oxide units; polyoxyethylene alcohols having 4 and 7 ethylene oxide units; poly(ethylene glycols) having M.W. 4000, 9000 and 20000; hexadecyltributylphosphonium bromide (HDTBPB), tetraphenylphosphonium bromide (TPPB),N,N,N,N,N',N',N-examethylhexamethylenediammonium bromide (HMB), benzyl(di-isobutylphenoxyethoxy) dimethylammonium chloride (Hyamine 1622), hexadecyltrimethylammonium bromide (HDTMAB), hexadecyldimethylbenzylammonium chloride (HDDMBAC) and tetrabutylammonium chloride (TBAC). HDDMBAC, as well as all the substances examined which contained an ethylene oxide chain, completely suppressed the copper peak. HDTBPB and TPPB partially suppressed the peak, whereas HDTMAB, HMB and Hyamine 1622 enhanced it. TBAC was without effect. In 0.2M EDTA at pH 4.5 containing TBAC at 0.01M concentration and 10 ppm of Rokafenol N-3, Cu(II), Pb(II) and Bi(III) can be tolerated at concentrations of up to 0.05M, the height of the thallium peak being unaffected. The precision of the determination (3-10%) and the recovery are satisfactory. A 10(3)-fold ratio of Fe(III) to Tl(I) does not interfere with the determination.

Determination of thallium in lead salts by differential pulse anodic-stripping voltammetry.

The determination of trace levels of thallium in lead and lead salts by differential pulse anodic-stripping voltammetry has been made possible by using a surfactant as an electrochemical masking agent in addition to a complexing agent. In 0.2M EDTA at pH 4.5 as supporting electrolyte without surfactant, lead at concentrations below 0.5mM does not give a peak. When the electrolyte also contains tetrabutylammonium chloride (TBAC) at 0.01 M concentration, lead can be tolerated at concentrations up to 0.05M, while the height of the thallium peak is unaffected. It is thus possible to determine 5nM T1(I) in the presence of 0.05M Pb(II), i.e., Tl at the 1 x 10(-5)% level in lead. The precision of the determination (1-4%) and the recovery are satisfactory. Neither an 800-fold excess ratio of Cu(II) to Tl(I) nor a 10(7)-fold ratio of Bi(III) interferes in the determination. Thallium has been determined in a range of lead salts of various degrees of purity.

Determination of thallium and lead in cadmium salts by anodic stripping voltammetry with addition of surfactants to suppress the cadmium peaks.

Conditions have been found which make possible the determination of thallium and/or lead in cadmium and its salts without preliminary separation. The electrochemical activity of the cadmium, which usually interferes in the determination of thallium, is inhibited by the addition of 0.01% of polyethylene glycol of M.W. 4000. Thallium is determined by electrolysis at -0.74 V vs. SCE, in 0.1M EDTA solution: 10(-1)M thallium can be determined in the presence of 0.1M cadmium, while copper and lead at 10(-2)M and 10(-5)M respectively do not interfere. Lead is determined in 0.1M acetic acid containing 0.1% cetyltrimethylammonium bromide (CTAB). The addition of CTAB shifts the cadmium peak, as well as the optimum deposition potential for cadmium, to more negative values, making it possible to determine lead in the presence of cadmium as long as the deposition potential lies in the range between -0.50 and -0.56 V vs. SCE. Lead can be determined in the presence of ten times as much thallium.

Application of polyethylene glycol for "electrochemical masking" in direct-current polarography.

The use of polyethylene glycols (PEG) of molecular weight from 200 to 15,000 for electrochemical masking has been investigated. A pH-4.4 tartrate buffer was found to be the most suitable supporting electrolyte, and 0.1% the optimum PEG concentration. PEGs of m.w. below 600 had little effect on the waves examined, and are useless for electrochemical masking. Under the conditions chosen, the waves of Bi(III), Sb(III) and In(III) are completely suppressed; the Cd(II) and Pb(II) waves are shifted to more negative potentials, and the Tl(I) wave is scarcely affected by PEGs. The Cu(II) wave behaves differently from the others. A method is proposed for the determination of lead and/or thallium in the presence of up to 5000-fold w/w ratios of bismuth, antimony or indium. The determination of both lead and thallium is only possible when the amounts are not too different, as the waves are quite close. Copper(II) interferes.