摘要:

Following a short introduction to the technique of laser induced breakdown spectrometry for the determination of elements, this min-review will concentrate on the novel and most recent applications which show the advantages of the technique over more conventional atomic spectroscopic techniques. These applications include environmental, metals, liquids, aerosols or gases, non-metallic solids, and advanced materials.

ISSN:0003-2719    

DOI:10.1080/00032719908542960

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

An inhibition immunoassay for the determination of total 7-hydroxycoumarin (7-OHC) in human serum samples using the BIACORE biosensor is described. 7-OHC-BSA was immobilised onto BIACORE sensor chips and 7-OHC was premixed with a polyclonal anti-7-OHC antibody and injected over this surface. Excess antibody bound to the immobilised conjugate, generating a binding response that was inversely proportional to the amount of 7-OHC in the sample. The sample buffer was formulated to minimise non-specific binding of serum components to the sensor surface. Regeneration of the sensor surface was optimised such that the conjugate-coated surface retained acceptable antibody-binding capacity over 64 binding-regeneration cycles. The recovery of free drug from samples spiked with 7-hydroxycoumarin-glucuronide (7-OHCG) approximated 100%, while the inter- and intra-day coefficients of variation for the assay were less than 8.76% for 5 replicates. The assay had a measuring range of 0.5 – 80 μg/ml. This BIACORE-based immunoassay for 7-OHC could be performed using crude samples and both the reproducibility and sensitivity compared well to established methods of analysis.

ISSN:0003-2719    

DOI:10.1080/00032719908542961

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Tetracycline hydrochloride-selective electrodes of both the coated wire and the conventional polymer membrane types have been prepared. They are based on incorporating the tetracycline-phosphotungstate ion-associate in plasticized poly(vinyl chloride) film. A Nernstian response is shown by these electrodes within certain concentration ranges depending on the type of electrode. The effect of pH of the test solution and time of soaking on the electrodes' performance are studied. The electrodes are highly selective for tetracycline with respect to several inorganic cations, sugars and some amino-acids of significant importance in biological fluids and pharmaceutical preparations. The standard cell potentials, E°, were determined at different temperatures and used to calculate the isothermal temperature coefficient of the cell. Tetracycline is determined successfully in pure solutions and in pharmaceutical preparation using the standard additions method and potentiometric titration.

ISSN:0003-2719    

DOI:10.1080/00032719908542962

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A Furaltadone (FD) ion-selective PVC membrane electrode based on the ion-pair complex of FD with sodium tetraphenylborate was prepared with dioctyl phthalate as a plasticiser. The electrode exhibits a linear response with an approximate Nernstian slope (50 mV decade−1at 200C) with the concentration range 2.18 x 10−5–2.18 x 10−4FD. The effects of ionic strength and pH of the test solution on the electrode performance were studied. The electrode exhibited very good selectivity for FD with respect to a large number of inorganic and organic cations of biological importance. The standard addition method and potentiometric titration were used to determine the FD in pure solution and in pharmaceutical preparations with satisfactory results.

ISSN:0003-2719    

DOI:10.1080/00032719908542963

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

DP+ion-selective PVC membrane electrode based on 2,3,11,12-dibenzo-5,9-diaza-4,9(10)-cis-diimino-1,13-dioxacyclopentadecane as a novel macrocyclic diimine crown ether is proposed. o-Nitrophenyl octyl ether as plasticizer and potassium tetrakis(4-chlorophenyl)borate as lipophilic salt were used. The electrode exhibits a Nernstian response for 1.0 x 10−2-1.0 x 10−6mol 1−1DPCl with a slope of 58 mVdecade−1. The detection limit is 2.5 x 10−7mol 1−1. The electrode response was stable over a wide pH range (3-11). The lifetime of the electrode was about 2 months. The electrode shows a high selectivity towards inorganic cations. Among the organic cations tested, only hexadecyltrimethylammonium ion interferes. The electrode was suitable for determining the critical micelle concentration and as an end-point detector in the potentiometric titration of the cationic surfactants.

ISSN:0003-2719    

DOI:10.1080/00032719908542964

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A colorimetric assay for nitrite determination in beer based on c-type multiheme enzyme Nitrite reductase (NiR) isolated fromDesulfovibrio desulfuricansATCC 27774, was developed. Using the enzyme in solution, nitrite assay was linear in the 10−8– 10−2M range with a detection limit of 10−8M and a recovery ranging from 90 to 107%. The imprecision ranged from 4 to 10% on the entire calibration curve. With NiR immobilised onto a nylon coil, a flow reactor was developed which showed a narrower linear range (10−5– 10−2M) and a higher detection limit (10−5M) than with the enzyme in solution, but made it possible to reuse the enzyme up to 100 times (50% residual activity). Sample preparation was simple and fast: only degassing and beer dilution by buffer was needed. This enzymatic assay was in good agreement with the results obtained using commercial nitrite determination kits.

ISSN:0003-2719    

DOI:10.1080/00032719908542965

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Penicillin-binding proteins (PBPs) were shown to associate non-covalently with many other morphogene proteins (MGPs). Specific associations were assigned. The PBPs were labeled with spectroscopic/fluorescence (F/S) groups in the form of dansylated β-lactam probes. Competitive β-lactam binding of non-denatured PBP/MGP complexes led to characteristic patterns of F/S labeling by the probes. The salt-bridge specific reagent, ethanedinitrile, covalently linked various MGPs to the F/S labeled PBPs. Proteolysis of chromatographically purified F/S labeled fractions gave sets of peptides analyzed by MALDI-TOF to give MH data. Peptide mass-fingerprinting analysis revealed that covalent linkage occurred with other MGPs and not with non-MGP proteins of ∼3400 proteins in the SWISS-PROT r33 data base forE. coliK-12.

ISSN:0003-2719    

DOI:10.1080/00032719908542966

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

An analytical method for the determination of diclofenac with tolfenamic acid as the internal standard was developed and validated in human plasma by capillary gas chromatography-mass spectrometry (GC/MS). After the addition of the internal standard, the compounds were extracted from plasma at acidic pH into diethylether, which was then evaporated to dryness. The compounds were derivatized with pentafluoropropionic anhydride (PFPA) and a mixture (1000:2:3, v/w/w) ofN-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA), ammonium iodide (NH4I), and dithioerythritol (DTE). They were determined by GC/MS at m/z 349 (a molecular ion) for diclofenac and m/z 270 (a base ion) for tolfenamic acid. The recovery of this procedure was 97.8%, and the linearity for calibration was 0.9907 as the coefficient factor. The detection and quantitation limits were 0.1 and 0.5 ng/mL, respectively.

ISSN:0003-2719    

DOI:10.1080/00032719908542967

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Ion-association complexes of promazine HCl (I), chlorpromazine HCl (II), promethazine HCl (III), imipramine HCl (IV) and ciprofloxacin HCl (V) with [Co(NO2)6]3−were precipitated at their optimum conditions of pH and ionic strength (NaCl-HCl/NaOH) and the excess unreacted cobalt complex was determined using atomic absorption spectrometry (AAS). The applicability of the method for determination of the above drugs in pure solution, pharmaceutical preparations and urine was examined. The drugs can be determined in the ranges 0.485-4.854, 1.619-16.197, 1.441-14.410, 1.415-14.154 and 0.578-5.787 mg/25 ml of I, II, III, IV and V, respectively, with mean relative standard deviations 1.05-1.53% and recovery values of 98.85±0.31-100.09±0.54% indicating high precision and accuracy. The sensitivities of the proposed method were 11.73, 23.00, 30.00, 38.00 and 12.69 μg/ml for the drugs I, II, III, IV and V, respectively; and the detection limits for determination of the investigated drugs were 3.10, 7.20, 13.80, 18.30 and 6.63 μg/ml for I, II, III, IV and V, respectively. The suggested method has been applied for the determination of the above mentioned drugs in their pharmaceutical formulations and urine.

ISSN:0003-2719    

DOI:10.1080/00032719908542968

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A sensitive reduction peak of paclitaxel is obtained by adsorptive stripping voltammetry in 0.1M NH3- NH4Cl at an accumulation of 60s with stirring. The peak potential is −1.43V (vs.Ag/AgCl). The peak current is directly proportional to the concentration of paclitaxel (1.0x10−8- 1.0x10−6M), with a detection limit of 5.0x10−9M, The method has been applied to the determination of paclitaxel in semi-finished products. The reduction process is quasi-reversible with adsorptive characteristics.

ISSN:0003-2719    

DOI:10.1080/00032719908542969

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor