Showing papers on "Color reaction published in 2001"
TL;DR: A sensitive and simple spectrophotometric method for the estimation of catechol and its derivatives like dopamine hydrochloride (DPH), levodopa (LDP), methyldopa (MDP) and adrenaline hydro chlorine (ADH) in both pure form and in pharmaceutical formulation, is described.
205 citations
TL;DR: In this article, a maximum capacity of ca. 40μm-pH−1/ml−1 was found at pH 10.2 when [Mg2+] was 0.045m.
152 citations
TL;DR: Cyanide and azide disappeared by evaporation from beverages during 25 degrees C storage under open conditions in a pH-dependent manner as a function of their respective pKa values of 9.2 and 4.6.
Abstract: A rapid screening method was developed for the determination of the toxic volatile anions, cyanide and azide, in beverages. This method consisted of a microdiffusion extraction combined with spectrophotometry using the K~nig cyanide reaction and ferric azide complex formation in conjugation with cerium azide oxidoreduction. The time required to achieve full recovery in the extraction of hydrogen cyanide and hydrazoic acid from samples was considerably shortened by the diffusion temperature from 25~ to 40~ The time required to achieve saturated color development in the K~nig cyanide reaction was also shortened by incubation temperature to 40~ The interference in both azide color reactions was examined for volatile compounds. Cyanide interfered only the case of ferric azide complex formation. Sulfide, sulfate, nitrite, and acetic acid interfered in both the color reactions. The established method gave a detection limit of 6~M for cyanide and 0.5ram for azide, and it required only 1 h to determine both anions. Cyanide and azide disappeared by evaporation from beverages during 25~ storage under open conditions in a pH-dependent manner as a function of their respective pK a values of 9.2 and 4.6.
49 citations
TL;DR: The tolerance limits of Fe, Al, Zn, Ca and Mg are superior to those of other reagents such as Azomethine-H and AzometHine-HR and the proposed method was applied to the determination of boron in ceramic materials with satisfactory results.
Abstract: A sensitive and selective spectrophotometric method for the
determination of boron is described. The method is based on the colour
reaction between boron and the reagent
1-(2-hydroxy-3-methoxybenzylideneamino)-
8-hydroxynaphthalene-3,6-disulfonic acid (HMOA). In a
HOAc–NH4OAc buffer of pH 5.5, HMOA reacts with boron to
form a 1∶2 yellow complex with a maximum absorption at 423 nm. The
absorbance (λmax = 423 nm) is linear up to 1.2
μg ml−1 boron in aqueous solution with a repeatability
(RSD) of 1.12%. The molar absorptivity and Sandell’s sensitivity are
7.19 × 103 l mol−1 cm−1
and 0.0015 μg cm−2, respectively. The limit of
quantification and limit of detection were found to be 17.1 and 5.2 ng
ml−1, respectively. The interference of various ions was
examined in detail. All the metal ions studied can be tolerated in
considerable amounts; in particular, the tolerance limits of Fe, Al, Zn, Ca
and Mg are superior to those of other reagents such as Azomethine-H and
Azomethine-HR. The proposed method was applied to the determination of
boron in ceramic materials with satisfactory results.
19 citations
Journal Article•
TL;DR: A new reagent, 4hydroxyacetophenone–isatin-5-sulfonic acid (sodium salt) is proposed, which produces distinguishable colors for most of the amino acids, and this communication deals with this reagent.
Abstract: A variety of selective and non-selective reagents [1–18] are used in thin-layer chromatography for identification of amino acids. Such identification is very useful because of the occurrence of the amino acids as the structural units of proteins, in the free state in natural products, and for determination of the C-terminal amino acids of degraded proteins. Of the reagents generally used, ninhydrin, a non-selective reagent, is popular because of its remarkably high sensitivity [2], even though it produces the same purple color with all the amino acids except proline and hydroxyproline. To solve this problem a new reagent, 4hydroxyacetophenone–isatin-5-sulfonic acid (sodium salt) is proposed. This communication deals with this reagent, which produces distinguishable colors for most of the amino acids. With the proposed reagent detection limits for the amino acids range between 0.1 and 2.0 μg.
19 citations
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
TL;DR: The free radical scavenging property of fullerenes and their derivatives is demonstrated by a facile color reaction of C60 with the 1,1-diphenyl-2-picryl hydrazyl radical as mentioned in this paper.
Abstract: The free radical scavenging property of fullerenes and their derivatives is demonstrated by a facile color reaction of C60 with the 1,1-diphenyl-2-picryl hydrazyl radical. A rapid test by simply monitoring the reaction using ultraviolet-visible spectroscopy is suggested.
17 citations
TL;DR: In this paper, a high sensitive and selective spectrophotometric method for determination of germanium has been developed, which is based on the reaction of Germanium with a new reagent trimethoxylphenylfluorone (TMPF) in the presence of Triton X-100.
16 citations
TL;DR: A new, simple, selective and sensitive spectrophotometric procedure for the on-site quantification of iron at nano-gram levels in atmospheric precipitations, i.e. rain as sample source, has been applied to the determination of Iron at the ppb level in rain water samples.
Abstract: A new, simple, selective and sensitive spectrophotometric procedure for the on-site quantification of iron at nano-gram levels in atmospheric precipitations, i.e. rain as sample source is described. It is based on the color reaction of Fe3+ with SCN- ions in the presence of a cationic surfactant, i.e. cetylpyridinium chloride (CPC), in strong HCl solution, and subsequent extraction of the complex with N-octylacetamide into toluene or chloroform. The apparent molar absorptivity of the complex is 2.60 x 10(5) L mol(-1) cm(-1) at lambdamax = 480 nm at an enrichment factor (EF) of 10. The detection limit (causing higher absorbance than the sum of the blank absorbance (0.009) and 3 SD) is 5 ng mL(-1) Fe. Ions commonly associated with iron did not interfere in the present method. The effect of analytical variables, i.e. amount and type of the reagents, acidity, solvent, temperature, dilution, etc., in the determination of iron are discussed. The validity of the present method is checked with GF-AAS. The method has been applied to the determination of iron at the ppb level in rain water samples.
11 citations
TL;DR: The color reaction of palladium(II) with the new reagent OPT was studied in this article, where a yellow-brown soluble complex with the ratio of 1:4 was formed.
Abstract: The color reaction of palladium(II) with the new reagent OPT was studied. In the presence of cetyltrimethyl ammonium bromide (CTMAB), in pH 5.0-5.6 HAc-NaAc buffer solution, a yellow-brown soluble complex with the ratio of 1:4 was formed. The maximum absorption was at 299.0 nm, the apparent molar absorptivity e 2 9 9 . 0 n m = 1.38 × 10 5 l mol - 1 cm - 1 . Beer's law was obeyed in the range of 2-12 μg Pd(II)/25 mL. The method's sensitivity and selectivity were very good. It could be used to determine palladium(II) in a catalyst with satisfactory results.
7 citations
TL;DR: In this article, a highly sensitive method for determination of rhodium by laser thermal lens spectrometry based on the colour reaction between Rhodium and the new chromogenic reagent 5-bromo-(2-thiazolylazo)-5-diethylaminobenzoic acid (5-Br-TADEB) was developed.
Abstract: A highly sensitive method for determination of rhodium by laser thermal lens spectrometry based on the colour reaction between rhodium and the new chromogenic reagent 5-bromo-(2-thiazolylazo)-5-diethylaminobenzoic acid (5-Br-TADEB) has been developed. The experimental results show that in a acetic acid-sodium acetate buffer solution of pH 4.0–5.7 and in the presence of acetone, rhodium reacts with 5-Br-TADEB to form a 1 : 2 stable blue complex exhibiting an absorption maximum at 632 nm which is well-matched to the wavelength of the laser beam used (λ = 632.8 nm). The detection limit and linear range of rhodium(III) are 0.004 μg mL−1 and 0.01–0.08 μg mL−1, respectively. The method has also been applied to determine rhodium in catalyst samples with satisfactory results.
TL;DR: In this article, a red-coloured complex with maximum absorbance at 510 nm was obtained for phenytoin sodium with 0.01 mg/10 mL as visual limit of quantitation and provided a basis for a new spectrophotometric determination.
Abstract: Phenytoin sodium reacts with o-nitrobenzoic acid in alkaline media after heating for 10 minutes at 70 °C, to give a red coloured complex having maximum absorbance at 510 nm. The reaction is selective for phenytoin sodium with 0.01 mg/10 mL as visual limit of quantitation and provides a basis for a new spectrophotometric determination. The colour reaction obeys Beer’s law from 0.01 mg to 3 mg/10 mL of phenytoin sodium and the relative standard deviation is 0.29%. The quantitative assessment of tolerable amounts of other drugs is also studied.
TL;DR: In this article, the influence of anions on the color reaction between lead and 4-(2-pyridylazo)resorcinol (PAR) was studied by diffuse reflectance spectrometry.
Abstract: The influence of the nature of anions (iodide, bromide, thiosulfate, pyrophosphate, tartrate, and acetate) in the anionic lead complex adsorbed on a solid phase of a fibrous sorbent filled with the AV-17 anion exchanger on the color reaction between lead and 4-(2-pyridylazo)resorcinol (PAR) was studied by diffuse reflectance spectrometry. The influence of anions on the complexation of lead with PAR on the solid phase was discussed for different types of the color reaction. It was demonstrated that the reactions with iodide at pH 5–10 and with thiosulfate at pH 10 are significant in the determination of lead as three-component complexes on the support. In the presence of other anions, lead ions do not react with PAR on the AV-17 solid phase.
TL;DR: P-NITBA試薬の反応は3000ルクスの光照射条件下では, 約20分間で完了されているが, £1.967及びr=0.990の相関を示し,
Abstract: 芳香族アルデヒドは光照射下で血清グロブリンと反応し, 発色体を生成する. この反応はp-ジメチルアミノベンズアルデヒドを用いた血清総グロブリン濃度の測定法として応用されているが, 反応時間は45分と長い. そこで, 反応時間を短縮したより実用的な測定法を設定するため, 8種類の芳香族アルデヒドと血清グロブリンとの反応について検討し, このタンパク質の測定に適する発色試薬の選定を行った. 反応速度, 生成する発色体の吸収極大波長及び見掛けの分子吸光係数はベンズアルデヒドに結合した置換基 (p-NO2, m-NO2, p-OCH3, m-OCH3, p-CH3, p-Cl, p-N(CH3)2, p-OH) の求電子的置換基定数と関係があった. 反応速度は置換基にm-NO2やp-NO2を有する芳香族アルデヒドで最も大きく, p-ニトロベンズアルデヒド (p-NITBA) と血清グロブリンとの反応は3000ルクスの光照射条件下では, 約20分間で完了した. p-NITBA試薬とγ-グロブリンの反応で生成した発色体は600nm付近に吸収極大波長を示し, 見掛けの分子吸光係数は2.15×108 mol-1 cm2であった. p-NITBA試薬で得られた患者血清の測定値 (n=100) はビウレット法とブロムクレゾールグリーン法の組合せ法及びGoldenbergらの方法で得られた血清総グロブリン濃度とr=0.967及びr=0.990の相関を示し, この試薬が血清総グロブリン濃度の測定に応用できることが分かった. 本法は10μlの微量血清で実施でき, 同時再現性 (n=10) はRSD=2.3%以内であった.
Patent•
18 May 2001
TL;DR: In this paper, an inflow side pipe in a color reaction tape-type gas measuring apparatus is purged by a gas, as a gas to be measured, which is passed through a purification port on which a gaseous-chamical-substance capturing body is mounted.
Abstract: PROBLEM TO BE SOLVED: To provide a monitoring system which is not influenced by the contamination of an inflow-side pipe in a gas measuring apparatus and which is not influenced by the temperature and the humidity of ammonia or amines in a gas to be measured. SOLUTION: An inflow-side pipe in a color reaction tape-type gas measuring apparatus is purged by a gas, as a gas to be measured, which is passed through a purification port on which a gaseous-chamical-substance capturing body is mounted. A gas which contains a gaseous chemical substance from a selected measuring port is sucked in advance by the inflow-side pipe in the color reaction tape-type gas measuring apparatus. A measurement is performed, and the measured result of the color reaction tape-type gas measuring apparatus is stabilized. In this monitoring system, the temperature and the humidity of the concentration of a gaseous chemical substance in a gas are corrected.
Journal Article•
TL;DR: The conditions of color reaction of boric acid with 1 (2 hydroxy 3 methoxybenzyl amino) 8 hydroxynaphalene 3 6 disulfonic acid in buffer medium of ethamine at pH 6 5 were studied in this paper.
Abstract: The conditions of color reaction of boric acid with 1 (2 hydroxy 3 methoxybenzylidence amino) 8 hydroxynaphalene 3 6 disulfonic acid in buffer medium of ethamine at pH 6 5 were studied in the assy The maximum absorption wavelength of this coordination compound was 420 nm The coordination reaction showed a good linear relationship at the concentrations of boric acid of 0 4~0 6 mg/L The detection limit and molar absorptivity (e) was 0 08 mg/L and 4 6×10 4 L/(mol·cm) respectively. This method presented perfect selectivity under the existence of EDTA solution,had been successfully applied in the determination of boric acid in natural mineral water for drinking
Journal Article•
TL;DR: In this article, the condition of colour reaction of Cadmium(Ⅱ) with 2-[(5bromo-2-pyridyl)azo]-5-diethylaminophenol(5-Br-PADAP)in the presence of Surfactant has been studied.
Abstract: The condition of colour reaction of Cadmium(Ⅱ) with 2-[(5-bromo-2-pyridyl)azo]-5-diethylaminophenol(5-Br-PADAP)in the presence of Surfactant has been studied.The Cadmium(Ⅱ) can react with 5-Br-PADAP to form 1∶2 red complex in the NH 3·H 2O-NH 4Cl buffer solution (pH8.0) containing OP.The colour reaction can be accomplished in wide range of temperature and the colour is stable for at least 20 h.Complex has a maximum absorption wavelength at 560 nm.The apparent molar absorptivity is 3.51×10 5 L·mol -1 ·cm -1 .Beer's law is obeyed in the range from 0 to 400 μg/L for Cadmium(Ⅱ).This method possesses advantages of high sensitivity and good repeatability.It is applied to the determination of trace Cadmium in lead slag with satisfactory results.1fig.,2tabs.,5refs.