摘要:

A simple and fast kinetic method for the determination of pindone in baits was developed. It is based on the inhibitory effect of this indanedione rodenticide on the luminescence of the europium(III)-thenoyltrifluoracetone system in the presence of cetyltrimethylammonium bromide. The relatively long lifetime of this system allows the time-resolved mode to be used, which eliminates any fluorescence signal. To avoid the potential static background signal of the sample, the difference between the initial rate obtained in the absence and presence of pindone is used as the analytical parameter, which is obtained within only 0.2 s with the aid of a stopped-flow mixing technique. The calibration graph is linear in the range 0.1-10.0 μg ml−1pindone and the detection limit is 0.04 μg ml−1. The relative standard deviation is close to 3%. The recoveries obtained by applying the method directly to the analysis of bait samples ranged from 92.0 to 114%.

ISSN:0003-2719    

DOI:10.1080/00032719908542937

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The development of an on-line ammonia preconcentration system based on microdistillation is reported. The combination of microdistillation and flow injection gives rise to an improved analytical technique. This method has good throughput (15-20 samples per hour), requires a small sample volume (6.0 ml) and has a low detection limit (2 μg/l). Microdistillation brings the further advantage of using a pH electrode, non-specific for ammonia, as the sensing device. Evaluation of the method showed excellent correlation with the standard phenate method, and good precision for ammonia determination.

ISSN:0003-2719    

DOI:10.1080/00032719908542938

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The retention of 44 barbituric acid derivatives was determined on a porous graphitized carbon column using water-tetrahydrofuran mixtures as eluents. Good linear relationships were found between the logk values and the organic mobile phase concentration in the eluent. The slope and intercept values of the relationship were correlated with the physicochemical parameters of the barbituric acid derivatives by means of canonical correlation analysis. The results indicate that the electronic parameters exerted the highest impact on the retention with the effect of hydrophobicity being negligible. The data indicates that the retention mechanism of a porous graphitized carbon column considerably deviates from that of traditional reversed-phase column although the eluent systems are identical.

ISSN:0003-2719    

DOI:10.1080/00032719908542939

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The multivariate calibration methods, partial least square regression type 1 (PLS 1) and principal component regression (PCR), were proposed for the simultaneous spectrophotometry determination of Amaranth (E-123), Ponceau 4R (E-124), Allura red (E-129) and Red 2G (E-128) in their mixtures. The parameters of the chemometric procedures were optimized and the proposed method was validated with synthetic samples and applied to analyze these dyes in spiked samples of beverages with satisfactory results.

ISSN:0003-2719    

DOI:10.1080/00032719908542940

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A wavelet-based genetic algorithm using real-number coding and arithmetical crossover method in signal processing is described in this work. Due to the characteristic of the wavelet, an analytical signal can be represented by a finite linear combination of wavelet-based functions. Using a wavelet-based genetic algorithm to find the coefficients to such representation, an analytical signal can be reconstructed by the coefficients and the corresponding elementary function. Therefore the method can be used to compress and de-noise analytical signals because the insignificant information such as noise will not be reserved in the reconstructed signal. Both simulated signals and experimental multicomponent chromatograms are successfully compressed and de-noised with the proposed algorithm.

ISSN:0003-2719    

DOI:10.1080/00032719908542941

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A novel sensitive, simple and fast kinetic method for the determination of trace amounts of resorcinol (0.50 — 3.00 μg ml−1) based on its inhibitory effect on the formaldehyde catalyzed oxidation reaction of neutral red by bromate ion in acidic media is reported. The reaction is monitored spectrophotometrically by measuring the decrease in the absorbance of neutral red in an inhibited reaction at 524 nm using a variable - time method. The detection limit is 0.38 μg ml−1and the relative standard deviation of ten replicate measurements for 1 μg ml−1of resorcinol is 4.2%. The procedure was successfully applied to the determination of resorcinol in resorcinol - S topical cream.

ISSN:0003-2719    

DOI:10.1080/00032719908542942

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A kinetic spectrophotometric method for the determination of trace amounts of vanadium(V) is described. It is based on the catalytic action of this ion on the oxidation of Nile Blue by bromate, which yields a colorless product in acidic media. The reaction is followed spectrophotometrically by measuring the rate of decrease in absorbance at 585 nm and 30 °C. A fixed time method of 4.0 min from initiation of the reaction was used. Vanadium(V) in the range of 0.004-0.520 μg/ml can be determined. The proposed method is hardly subject to interference. The parameters affecting the sensitivity were optimized. The proposed method was used for the determination of vanadium in water and in milk samples.

ISSN:0003-2719    

DOI:10.1080/00032719908542943

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor