摘要:

AbstractAn indirect procedure for the determination of 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T) in mixtures via adsorptive stripping voltammetry is reported. This method takes advantage of the formation of a new pH‐dependent peak, which is obtained when these acids interact with Fe(II). The limits of detection are 1.7 ppb for 2,4‐D and 1.5 ppb for 2,4,5‐T. The relative standard deviations (for 10 determinations) are 6.2 and 5.7%,

ISSN:1040-0397    

DOI:10.1002/elan.1140020113

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY

摘要:

AbstractA chitin‐containing carbon paste electrode was found to give highly sensitive voltammetric waves for Fe(III)‐EDTA chelate both in cyclic voltammetry (CV) and in differential pulse voltammetry (DPV). Various conditions for the determination of trace Fe(III) were studied. The optimum chitin content in the carbon paste (graphite powder: mineral oil = 2:1) was 6% (by weight). In a solution of 0.01 M KCl and 3 × 10−4M EDTA (pH 3.0), the DPV peak potential for the reduction of Fe(III)‐EDTA was −0.05 V vs. Ag/AgCl. The peak current was proportional to the Fe(III) concentration between 2 × 10−7and 6.5 × 10−6M; the relative standard deviation for 2 × 10−6M Fe(III) was 2.6%. The method was fairly free from interference and could be applied to the determination of iron in both

ISSN:1040-0397    

DOI:10.1002/elan.1140020114

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY

摘要:

AbstractA new nicotine sensor for the simple, rapid determination of nicotine in tobacco products without prior separation is described. The sensor is a coated graphite electrode with silicotungstic acid as the active material in polyvinyl chloride with di(2‐ethylhexyl) phthalate as the plasticizer. At pH 5.5–6.0, it provides a Nernstian response to nicotine over 10−1to 10−6M; the detection limit is 7.4 × 10−7M, and the average slope is 58 mV/pN. The analytical recovery is 98.1 to 102.3%. Satisfactory results are obtained in comparison with silicotungstate gravimetric method and UV sp

ISSN:1040-0397    

DOI:10.1002/elan.1140020115

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe analysis of tin‐bismuth alloys using a new stripping technique, abrasive stripping voltammetry, is described. Small amounts of the alloy are transferred by mechanical abrasion from the solid alloy onto the surface of a paraffin‐impregnated graphite electrode. These traces are anodically stripped off with differential pulse voltammetry. The ratio of the tin and bismuth peak currents provide a measure of their relative content in the alloy. The determinations have standard deviations of about 5%. Peak potentials are reproducible within a 20‐mV

ISSN:1040-0397    

DOI:10.1002/elan.1140020116

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY

ISSN:1040-0397    

DOI:10.1002/elan.1140020119

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY