Flow injection method for antimony(III) based on its enhancement of the molybdenum blue reaction

Lacy, Nathan; Christian, Gary D.; Růžička, Jaromír

doi:10.1016/s0003-2670(00)86573-3

Cited by 9 publications

(3 citation statements)

References 26 publications

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“…A plot of the scores for each sample from Table II is provided in Figure 18 and shows how the samples are grouped along the first source of variance. Sample groups [1, 2, 3, 4], [5,6,7,8], [9,10,11,12], and [13,14,15,16] correspond to increasing silicate concentration at constant phosphate, while sample groups [1, 5,9,13], [2,6,10,14], [3,7,11,15], and [4, 8,12,16] correspond to increasing phosphate at constant silicate. If one were to "connect the dots" for these two separate groupings, a series of four vertical and four horizontal lines would result.…”

Section: Time (Sec)mentioning

confidence: 99%

“…Thirdly, the adoption of nonselective extraction procedures is ultimately reflected in great complexity of the final chromatogram when the simultaneous analysis of variously substituted anilines is performed. To enhance selectivity, extraction procedures of aromatic bases from water by cation exchangers have been proposed (8)(9)(10)(11). However, these methods generally have detection limits higher than 1 pg/L.…”

Section: Time (Sec)mentioning

confidence: 99%

“…0003-2700/90/0362-1482S02.50/0 H3P04 + 6MoVItotal -12-molybdophosphoric acid + 9H+ (1) utilizing antimony to enhance the reaction rate (9,10). For further specifics on the molybdenum blue reaction the reader is referred to the above reference and references therein.…”

Section: Introductionmentioning

confidence: 99%

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Enhancement of flow injection optosensing by sorbent extraction and reaction rate measurement

Lacy¹,

Christian²,

Růžička³

1990

Anal. Chem.

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The molybdenum blue reactlon for the determination of phosphate Is used as a model to Illustrate the extension of the use of hydrophoblc sorbents In flow Injection analyds for the preconcentratlon of an anlon and for on-cdumn detec#on, Le., optosenslng. Optosenslng provides for real-time monltorlng of the rate of slgnai change, dA /d T , so that the rate of color devebpment durlng the reductlon step of the analysis can be measured. The synerglstlc relationship between the rates of formation of the phosphate and sHlcate heteropdy complexes is examlned. A kinetic optosenslng method has been developed In which the difference In reduction rate for the heteropoly complexes allows simultaneous determlnatlon of phosphate, In the parts per bllllon range, and slllcate, in the parts per mllllon range. The system used an Inexpensive mlnlspec-20 spectrophotometer wtth a net path length through the sorbent of less than 2 mm. Partlal least-squares analyds was used to analyze the data, and predlctlon errors of approxlmately 10 % were obtained for both components. INTRODUCTIONEnhancement of the selectivity of instrumental methods by flow injection analysis (FIA) has been accomplished by various means, such as the use of solvent extraction ( 1 ) and gas diffusion techniques (2). These may be considered homogeneous techniques in that the chemistry occurs in the homogeneous media of the flowing stream itself. Additionally, sensitivity has been increased by on-line preconcentration using ion exchange (3). The latter technique may be viewed as heterogeneous since isolation of the analyte on a surface has occurred, creating a region of increased concentration within the flowing stream and may be considered similar to solute focusing (4). Only very recently, attention is being given to the concept of sorbent extraction in FIA, which has been used so far only for the preconcentration of metal complexes (5) using hydrophobic interactions on C-18. Further increases in sensitivity can be achieved by flow injection optosensing (6), which is based on the measurement of an analyte retained on the solid sorbent surface. Use of cation exchangers for this purpose has been described by Yoshimura and Waki (7) while Valcarcel and co-workers (8) used an anion exchanger in a detailed study of the iron(II1) thiocyanate complex. This paper deals, for the first time, with the use of sorbent extraction for the optosensing of anionic complexes and exploits in a novel way the differential kinetics of competing species.The present study of differential kinetics allows for the simultaneous determination of two analytes or the determination of one analyte in the presence of an interferent. Thus, while to date the use of sorbents has been driven by the "all or nothing" philosophy that focuses on steady-state chemistry, it is shown in this work how the horizon of applications for sorbent use in FIA can be greatly broadened with the incorporation of kinetic techniques.Previous work in this laboratory has focused on the enhancement of instrumental response at roo...

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