摘要:

Flow micro-calorimeter so-called enzyme thermistor (ET) is nowadays increasingly used for rapid screening of the sorbents with immobilized protein ligands. In the present paper, chlorotriazine-, dialdehyde-, formylmethyl-, oxirane- and diazotized derivatives of bead cellulose were applied as matrices for immobilization of Concanavalin-A (Con-A). The amounts of free-accessible Con-A in each of the above sorbents were evaluated: i.) by adsorption of invertase; ii.) by means of ELISA using both, mouse anti-Con-A antibody and pig anti-mouse antibody linked with peroxidase. Reactions sub i and ii were monitored in dual way; thermometrically, with the aid of an ET as well as using common spectophotometric methods. The results obtained by spectrophotometry and thermometry intercorrelated significantly (p=0.0028 and p=0.0001, for ELISA and the invertase, respectively). The amounts of immobilized Con-A were directly proportional with the ELISA signal of peroxidase reaction whether this was detected by means of ET (r=0.975, p=0.001) or by spectrophotometry (r=0.983, p=0.0005). Slightly less tight correlation was found between the amounts of immobilized Con-A and the activity of invertase in conjugates when they were assayed by means of thermometry (r=0.933, p=0.0065) and spectrophotometry (r=0.920, p=0.0094). The above data indicate, that thermometry may be considered as a method suitable for rapid evaluation of the amount and accessibility of immobilized Con-A.

ISSN:0003-2719    

DOI:10.1080/00032719508007411

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An enzyme electrode is made from a glassy carbon electrode covered with a gelatin membrane containing entrapped glycerol dehydrogenase (GDH) and diaphorase, and protected with a dialysis membrane. Based on amplification by the recycling reaction catalyzed by the two-enzyme systems, NAD+and NADH can be determined with 800–1200 times higher sensitivity than for the same electrode in a substrate sensing mode when the flow rate was 0.08 ml/min. The detection limit was about 0.03 μM for NADH. The amplification factors were around 1000 for 0.08 ml/min, with quite large variations between electrodes. They had decreased to about 70% of the original value after 7 days. The biosensor is intended for detection in immunoassays with alkaline phosphatase as a marker.

ISSN:0003-2719    

DOI:10.1080/00032719508007412

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This work assesses the feasibility of fluorescence detection of tetracycline in very optically dense mixtures of highly fluorescent media ingredients used in tetracycline production by fermentation. The fluorescence measurements are accomplished with a fiber optic probe. Seven different mixtures were examined in this study. Each one contained a nonfluorescent base of nutrients and salts along with one of the following media ingredients at 5 g/100 mL: cottonseed flour, corn gluten meal, soybean flour, distiller 's grains and solubles, corn steep liquor, brewer's yeast, and molasses. The concentration of tetracycline was varied in each mixture and fluorescence measurements were made at every concentration step. Excitation light of 390 nm was used to probe the samples, and emission spectra were obtained over the wavelength range from 400 to 600 nm. In most of the samples studied, the fluorescence intensity in the wavelength range corresponding to background media fluorescence (420–480 nm) decreased as the tetracycline concentration increased. The decreases in the short wavelength range might be explained by the absorption by tetracycline of 390 nm excitation light (in competition with absorption by the media) and/or by absorption of background media fluorescence by tetracycline. Frequently, the maximum emission of the mixtures shifted to longer wavelengths. The maximum approached that of tetracycline (approximately 520 nm). Plots of integrated fluorescence intensity, in the emission wavelength regions of 420-480 nm and 500-560 nm, versus tetracycline hydrochloride concentration reflect these shifts. We have found that the changes in fluorescence intensity in these two wavelength regions during tetracycline addition depend on the identity of the media component in the mixture. For corn meal, soybean, brewer's, and molasses media, the fluorescence in the short emission wavelength range decreases while that in the long region increases. In the case of distiller's and corn steep media, the fluorescence changes very little during tetracycline addition. Finally, in cottonseed medium, the fluorescence increases in both wavelength ranges. The data show that fluorescence can be used to detect tetracycline, at least qualitatively, in the presence of the highly fluorescent media ingredients.

ISSN:0003-2719    

DOI:10.1080/00032719508007413

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A procedure is presented for the determination of donor identity or commonality of origin among paraffinembedded tissues and slides. Samples are de-paraffinized with xylene and ethanol and subjected to ChelexRextraction. The Polymarker forensic DNA typing kit is utilized for identity testing. Following multiplex amplification, PCR product is verified on an agarose gel and then the samples are geiotyped using reverse dot-blot hybridization. When this procedure was applied to paraffin-embedded samples involved in a legal action, all samples were successfully genotyped. The advantages of using this procedure are discussed.

ISSN:0003-2719    

DOI:10.1080/00032719508007414

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In ligand binding assays, the separation of bound and free fraction of the labeled ligand is very important. Dialysis is generally overlooked as separation technique since it requires large volumes and long analysis times. The availability of the ASTED-system (Automated Sequential Trace Enrichment of Dialysates) might open ways for a complete automation of immuno assays including the separation step.

ISSN:0003-2719    

DOI:10.1080/00032719508007415

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This work presents a method in which a desired protein may be separated from a biological protein preparation and identified by highly specific monoclonal antibody. The desired protein may be isolated from crude protein preparations by this method. The protein remains intact and stable throughout the procedure. This method utilizes common nonreducing conditions of polyacrylamide gel electrophoresis (PAGE), and Western Blot transfer of protein. This isolation of the desired protein can be accomplished for a microgram or tens of micrograms of material. The application of Western blot technique with monoclonal antibody permits the highest specificity in terms of identifying the target protein. In addition to identifying the target protein the method can isolate sufficient amounts for further characterization.

ISSN:0003-2719    

DOI:10.1080/00032719508007416

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A direct colorimetric method was described for the rapid, sensitive and accurate determination of dibucaine, lidocaine, bupivacaine, procaine and tetracaine in pharmaceutical preparations. The method involves the use of haematoxylin reagent in the presence of boric acid to give a reddish-violet chromogen (λmax= 555 nm). Beer's law was obeyed in the range from 2–60 μg/ml. No interference was observed from the commonly present additives or agents in pharmaceutical formulations.

ISSN:0003-2719    

DOI:10.1080/00032719508007417

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A new heteronuclear complex, rare earth (III)-copper (II)-m-trifluomethyl chlorophosphonazo (CPA-mCF3) system for determining trace rare earth ions is presented. In a medium of 0.02mol/L NH4Cl,1. 0×10−3mol/L Cu(II),1.0×10−5mol/L CPA-mCF3, a very sensitive polarographic adsorptive wave is observed by using a single sweep oscillopolarograph at about –0.83V (vs. Ag/AgCl). The linear relationship between the peak current and the concentration of rare earth exists from 6. 0×10−9to 1. 0×10−6mol/L. The detection limit of rare earth is down to 2. 0×10−9mol/L for Tm3+. This method has been applied to determine trace RE in several samples of Chinese tea. The results are satisfactory. The composition of the complex is detected as RE (II): Cu (II): CPA-mCF3= 1: 1: 2.

ISSN:0003-2719    

DOI:10.1080/00032719508007418

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Two flow-injection methods for the determination of 4-aminobiphenyl by amperometry (glassy carbon electrode) and spectrophotometry are proposed. A sample volume of 200 or 400 μl containing an analyte concentration of 0.1–1.0 μg ml−1or 0.8–24.0 μg ml−1for amperometric or spectrophotometric detection, respectively, is injected into a carrier stream containing 0.04 or 0.02 M Britton-Robinson buffer at pH 10.0 or 8.0, respectively.

ISSN:0003-2719    

DOI:10.1080/00032719508007419

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Arsenic (III), arsenic (V), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) were separated by ion-exchange chromatography. The elution sequence was as follows: 1.5 M ammonia followed by 0.12 M hydrochloric acid yielding As(III); 1 M hydrochloric acid followed by water yielding first As(V) and then MMA. Detection was performed by hydride generation-atomic absorption spectrometry.

ISSN:0003-2719    

DOI:10.1080/00032719508007420

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor