摘要:

A new type of a fluorescent receptor system specific for sialic acid has been prepared. For the preparation of this artificial receptor a polymerization reaction using allylamine, vinylphenylboronic acid and ethylene glycol dimethacrylate in the presence of sialic acid as template was carried out. After splitting off the template molecules, a suspension of the polymer was used in reaction with OPA reagents, both in the presence and absence of sugars. It was found, that sialic acid promoted the fluorescence development in this system, probably as a result of the so-called “gate effect”, resembling natural occurring receptors.

ISSN:0003-2719    

DOI:10.1080/00032719608000997

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A new approach for the determination of bilirubin by an enzyme-based fiber-optic fluorescence biosensor is presented. Bilirubin is oxidized to biliverdin by bilirubin oxidase, and is quantitatively determined by measuring the fluorescence intensity change caused by the oxygen consumption in the enzymatic reaction. Bilirubin oxidase is immobilized onto an affinity membrane which is layered onto an optical indicating membrane. Two membranes are fixed around the common end of a bifurcated fiber-optic bundle. The limit of detection is 4.4 × 10−7M. The linearity of calibration curve is between 4.4 × 10−7M and 3.0 × 10−4M.

ISSN:0003-2719    

DOI:10.1080/00032719608000998

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Enzyme modified carbon paste electrodes were developed for the determination of L- and D-lactate based on D-lactate dehydrogenase and L-lactate oxidase, respectively. D-lactate dehydrogenase was coimmobilized with a redox mediator bound to a polymer backbone and the cofactor NAD+. L-lactate oxidase and horseradish peroxidase were coadsorbed onto heat treated graphite powder, which was mixed with silicon oil to prepare the corresponding carbon paste.

ISSN:0003-2719    

DOI:10.1080/00032719608000999

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

An on-line photochemical spectrofluorimetric method for the determination of nicotinamide is proposed. It is based on the conversion of nicotinamide in an acidic medium into an intensively fluorescent compound. The calibration graph was linear up to 10.0 μg ml−1nicotinamide (r = 0.999), the limit of detection was 0.60 ng ml−1nicotinamide and the relative standard deviations were 1.5% (n = 6), 2.1% (n = 6) and 2.1% (n = 6) for 50 ng ml−1, 0.70 μg ml−1and 1.0 μg ml−1nicotinamide, respectively. The kinetic behaviors of the reaction and the effects of some experimental conditions were investigated. Its application to assay of vitamin B complex tablets was found to be satisfactory.

ISSN:0003-2719    

DOI:10.1080/00032719608001000

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Electrochemical behavior of dopamine and ascorbic acid binary mixture was examined by cyclic voltammetry and the analysis of a each component was performed by differential pulse voltammetry. The electrochemical behavior of these molecules on poly-3-methylthiophene, polypyrrole, polyaniline electrodes were compared. The effects of electrolyte type and its pH, and the film thickness on the voltammetric resolution of these molecules were systematically examined.

ISSN:0003-2719    

DOI:10.1080/00032719608001001

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A method for the simultaneous determination of 4-(indol-3-yl)butyric acid (IBA) and α-naphthalene acetic acid (NAA) in mixtures by first-derivative spectrofluorimetry has been developed. The method is based on their native fluorescence at an apparent pH of 8.0 in an aqueous-ethanol medium (50% v/v ethanol). IBA was measured at λem= 336 nm, and NAA at λem= 358 nm. The range of application is between 0.2 and 100.0 μgl−1for IBA and between 0.2 and 50.0 μgl−1for NAA. The accuracy and precision of the method are reported. The method was applied to the determination of IBA and NAA in synthetic mixtures and commercial formulations.

ISSN:0003-2719    

DOI:10.1080/00032719608001002

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Several graphical methods (zero-crossing and multiple linear regression analysis) are described to carry out the simultaneous determination of salicylamide (S) and acetylsalicylicacid (ASA) in the ranges 1.0–30.0 and 2.0–25.0 μg/ml, respectively; with detection limits of 0.15 and 0.19 μg/ml and quantitation limits for both drugs, in the presence of the maximum of the other analyte, of 4.0 and 2.0 μg/ml for the former and later method, respectively. A multi-wavelength regression method was also used to determine the aforementioned binary mixture and the ternary mixture of salicylamide, salicylic acid (SA) and acetylsalicylic acid in the same ranges with equal detection limits for the binary mixture, and quantitation limits of 4.0 for S and SA, and 5.0 for ASA in the presence of the maximum of the others. Both graphical and numerical methods were found to provide good results in the resolution of several binary and ternary synthetic mixtures, even when the different compounds showed overlapped spectra. However, the MULTIC program allows the determination of higher analytes concentration ratios. When the graphical methods were used, errors were higher than 5% for salicylamide/acetylsalicylic acid ratios equal to 10/1 or 1/10. This shortcoming was not observed when the multi-wavelength regression method was used.

ISSN:0003-2719    

DOI:10.1080/00032719608001003

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The odor in sterile solution lincomycin hydrochloride (S.S. Lincocin) subjected to terminal heat sterilization is due primarily to methyl mercaptan (CH3SH), secondarily to dimethyl disulfide (DMDS). Methyl mercaptan is generated by cleavage of the methyl mercaptyl group from the pyranoside ring in lincomycin; DMDS results from subsequent oxidation of CH3SH. A splitless headspace GC method was developed to detect and quantify the two compounds. Peak identification was made by injection of authentic standards in conjunction with chromatographic sniffing. CH3SH and DMDS were quantified by standard addition and were found to be present at about 1 and 0.05 ppm, respectively, in a lincomycin solution heated at 80°C for 30 minutes. These levels are well above the documented odor thresholds for these two compounds in water. In contrast, no CH3SH was detected over unheated lincomycin. The amounts of CH3SH and DMDS generated correspond to a 0.003% decrease in drug concentration.

ISSN:0003-2719    

DOI:10.1080/00032719608001004

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A method is described for the reliable determination of copper, lead, cadmium and zinc in natural waters by anodic stripping potentiometry with the use of a novel combined electrode. The method involves two stripping cycles during which copper is initially determined on its own, followed by simultaneous determination of lead, cadmium and zinc after addition of gallium (III) ions. The optimum conditions include 0.01 M HCl as supporting electrolyte, 10 mg/L Hg (II) as chemical oxidant; Edep(Cu)-700 mV vs Ag/AgCl; Edep(Pb,Cd,Zn)-1200 mV vs Ag/AgCl; tdep10s; 150 μg/L Ga (III); sample rotation rate 5 and rest period 30s. Under these conditions, as low as 0.06 μg/L Cu (0.7% RSD); 0.2 μg/L Pb (13% RSD); 0.04 μg/L Cd (7.8% RSD) and 0.06 μg/L Zn (5.5% RSD) can be determined reliably. A linear concentration range of 0–110 μg/L was obtained for the four metals. The successful application of the method to reference fresh water, creek water and tap water is demonstrated.

ISSN:0003-2719    

DOI:10.1080/00032719608001005

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A study of the fluorescence system of the Eu3+-2-benzoyl-indan-1,3-dione-trioctylphosphine oxide-Triton X-100 was made. The excitation and emission wavelengths were 348 and 612 nm, respectively. The fluorescence intensity was a linear function of the concentration of europium in the range 1.0×10−8- 1.0×10−6mol/L. The detection limit was 4.0×10−9mol/L. The standard addition method was used for the determination of europium in rare earth oxides, with satisfactory results.

ISSN:0003-2719    

DOI:10.1080/00032719608001006

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor