Topic
Color reaction
About: Color reaction is a research topic. Over the lifetime, 1194 publications have been published within this topic receiving 19579 citations.
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TL;DR: 3,5-Dibromo-4-hydroxyphenylflurone showed outstanding analytical characteristics for spectrophotometric determination of molybdenum, and has very high sensitivity and selectivity.
Abstract: A novel spectrophotometric method based on a new reagent,
3,5-dibromo-4-hydroxyphenylflurone, was developed for the determination of
molybdenum in plants and seeds. 3,5-Dibromo-4-hydroxyphenylflurone showed
outstanding analytical characteristics for spectrophotometric determination
of molybdenum. The reaction conditions are simple and stable. In 0.2 mol
l−1 phosphoric acid medium (which can combine with iron
and other metal ions and greatly improves the selectivity of the color
system), molybdenum(VI) reacts with
3,5-dibromo-4-hydroxyphenylflurone to form a 1∶2 red complex with an
absorption maximum at 530 nm, the color reaction can completed in 2 min and
the absorbance of the molybdenum complex remains stable for at least 72 h
at room temperature. Its stability constant is 1.21 × 1028
at 25 °C. Beer’s law is obeyed over the range 0–0.6 μg
ml−1 Mo(VI). The reagent has very high
sensitivity and selectivity; the molar absorptivity of the complex is 1.35
× 105 l mol−1 cm−1 and
the limit of quantification, the limit of detection and relative standard
deviation (n = 10) were found to be 6.7 ng ml−1,
2.2 ng ml−1 and 1.01%, respectively. Cu (50000-fold), Fe
(20000-fold), K (20000-fold), NH4+ (20000-fold), Mg
(15000-fold), Zn (10000-fold), Na (10000-fold), Al (4000-fold), Ca
(25000-fold), Mn (2000-fold), Ce (500-fold), Cr (400-fold) and Bi
(200-fold) do not interfere with the determination of trace levels of
molybdenum up to the excesses indicated. The selectivity is much superior
to that of other published methods. The proposed method was applied to the
direct determination of molybdenum in plants and seeds with satisfactory
results. The synthesis of the reagent and conditions of color reaction were
studied in detail.
18 citations
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TL;DR: In this paper, a bis-azo dye, 2,6-bis(1-hydroxy-2-naphthylazo)pyridine as spectrophotometric reagent was proposed for the determination of zinc(II) using a simple, sensitive, and highly selective method.
Abstract: A simple, sensitive, and highly selective method is proposed for the determination of zinc(II) using a bis-azo dye, 2,6-bis(1-hydroxy-2-naphthylazo)pyridine as spectrophotometric reagent. At pH 7.8, in 50% (v/v) ethanol–water medium, the complex is found to obey Beer’s law up to 1.3 mg/L with an optimum concentration range between 0.19 and 1.0 mg/L. Sandell’s sensitivity of the color reaction was calculated to be 0.0011 μg cm−2 with molar absorptivity of 6.0 × 104 L mol−1 cm−1 at 560 nm. The optimum conditions for the determination of Zn(II) with the reagent were ascertained. The complexation at different pH was studied in water–ethanol medium. The composition of the complex is 1:2. The action of some interfering ions was verified, and the developed method applied successfully for the estimation of zinc levels in food and milk samples, and the results were then compared with those obtained by using AAS.
18 citations
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TL;DR: In this article, the Munsell system of color measurement was used to measure the color of lactose solutions in which heat has produced varying shades of brown have been described and defined in numerical terms.
18 citations
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TL;DR: A novel bistriazene, 4,4'-bis(3-(4-phenylthiazol-2-yl)triazenyl)biphenyl (BPTTBP), and its highly sensitive color reaction with Hg(2+), which has been successfully applied to spectrophotometric determination of mercury in waste water samples.
18 citations
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TL;DR: In this paper, seven pyridylazo dyes containing the m -tolylenediamine group were synthesized and their analytical potential for the determination of cobalt was studied spectrophotometrically.
17 citations