Indirect Spectrophotometric Determination of Sulphide with the Complex of Cd(Ⅱ)-5-Br-PADAP-CPB

By the use of CPB, Cd(Ⅲ) forms a highly sensitive complex with 5-Br-PADAP in aqueous solution, molar absorptivity εis 1. 21 ×105 1. mol-1. cm-1.Trace amount of sulphide can be determined from its effect on the complex of Cd (Ⅲ)-5-Br-PADAP-CPB, sulphide in the range 0~3. 2 ×10-6mol dm-3 causes a decrease in absorption, that is a linear function of the concentration, For 13ng cm-3 sulphide, common metal ions such as Na+, K+, Ca2+, Mg2+, Al3+ and anions such as CO (24μg cm-3). S2O (22μg cm-3). PO (20μg cm-3) etc. do not interfere. A method for the indirect determination of sulphide in beer and in dustrial waste water with good selectivity and accuracy is described.

Solid-liquid Extraction Spectrophotometric Determination of Copper with 2,9-dimethyl-1,10-phenanthroline

Solid liquid extraction of copper ion (I) with 2, 9-dimethyl-1, 10-phenanthroline (neo-cuproine, DMP) into molten naphthalene followed by chloroform spectrophotometric determination has been studied experimentally. The ternary complex Cu(I)-DMP-ClO4 was extracted quantitatively into molten naphthalene in the range of pH from 5 to 6 at 85 C-. Absorbance was spectrophotometrically determined at 459 nm against the reagent blank after the solid naphthalene layer was anhydrously dissolved in chloroform. Beer's law is obeyed over a concentration range of 0.5-70 mug/mL. The molar absorptivity and Sandell's sensitivity are 1.0x10(4) L/(mol(.)cm) and 0.0099 mug(.)cm(2) respectively. In addition, the various conditions on determination and the interference of coexisted ions were discussed, and the method was applied to the determination of copper ion both in tea samples and cadmium sulfate reagents. The results are in good agreement with those obtained by ICP AES method.

STUDY AND APPLICATION OF SPECTROPHOTOMETRIC DETERMINATION OF MICRO AMOUNTS OF BISMUTH WITH MESO—TETRAKIS—(4—N—TRIMETHYL AMMONIUMPHENYL)PORPHINE

A new highly sensitive spectrophotometric method has been developed for the determination of micro amounts of bismuth (Ⅲ), based on the formation of Bi (Ⅲ)—meso—tetrakis—(4—N—trimethylammonium phenyl) porphine [T (4TMAP) P] complex. In the presence of Cd (Ⅱ), Bi(Ⅲ) reacts almost instantaneously with T (4TMAP)P in a 0. 6 mol/l NaAc—HAC buffer (PH5.8) at room temperature. The composition of the complex is T(4TMAP)P: Bi=1:1. The absorbance complex obeys Beer's law over the Bi(Ⅲ) concentration range 0.1—1.4 μg/ml. The linear relative coefficient γ is 0.9998. The apparent molar absorptivity was 1.75×10~5 1. mol^(-1). cm^(-1) at 463nm. The relative standard deviation of the method is 1.50％ for Bi(Ⅲ) 7ug/10ml (10 determinations). The interference of foreign ions has been examined. This simple and rapid method can be applied to the assay of Bi(Ⅲ) in some tablets directly.

Study on the Spectrophotometric Determination of Rare Earths with a New Chromogenic Reagent Dibromo-p-methyl-chlorosulfonazo(DBMCSA)

A new method for the determination of cerium subgroup rare earths was studied and reported ill this paper. It was found that cerium subgroup rare earth elements react with DBMCSA in 0.6 mol/L hydrochloric acid medium to form stable blue complexes. The absorbances of equal amounts of cerium subgroup rare earths are close to each other at their maximum adsorptive wavelength (641 nm). Beer's law is obeyed for 0-20 mu g of I ars earths in 25 mi of solution. The method has been applied to the determination of the total amount of cerium subgroup rare earths in steel and cast iron samples with satisfactory results.

Liquid waveguide capillary cell for the spectrophotometric determination of nanomolar iodate concentrations in marine waters

A new spectrophotometric method based on a liquid waveguide capillary cell for an enhanced detection was developed to measure nanomolar iodate concentrations.This method has a detection limit and precision of 1-2 nmol/L,which is equivalent to 10%that of conventional methods,a recovery of 97.7%-104.0%,and a working range of 10-120 nmol/L.Water samples were collected from three estuaries and one coastal ocean for testing,and the proposed technique detected as low as 11 nmol/L and 18 nmol/L iodate in these samples.This newly developed method is helpful in understanding the biogeochemical cycle of iodine in nature.

Titrimetric and Spectrophotometric Determination of Some Thiadiazole Derivatives by Using Amplification Reactions

The principle of using amplification reactions of iodine was employed in this paper to estimate the thiadiazole derivatives on basis of their reactions with iodine I chloroform, removal of the excess iodine and determination of the resulting iodide, after oxidation to iodate. The overall reaction gave an amplification of the iodide that is (12) times larger for the compounds: 2-amino-5-mercapto-1,3,4-thiadiazole (I);2,5-dimercapto-1,3,4-thiadiaole (II) and 2,5-diamino-1,3,4-thiadiazole (III) and (36) times for 2,5-dihydrazino-1,3,4-thiadiazole (IV) and (6) times for 5-mercapto-2[(3[5’-nitro-2-’furyl]·methylene)amino]-1,3,4-thiadiazole (V) and 5-mercapto-2[(3[5’-nitro-2-’furyl]-prop-2-enylidene)amino]-1,3,4-thiadiazole (VI). By titration, 1-mL of standard thiosulfate solution was found equivalent to 0.108 mg of (I);0.126 mg of (II), 0.16 mg of (III), 0.041 mg of (IV), 0.40 mg of (V) and 0.435 mg of (VI). Using the spectrophotometric detection for the amplification reaction gave high absorbance values at 605 nm for the blue starch-iodine complex. Beer’s law was obeyed up to 4.0 ppm for compounds (I and II);6.0 ppm for compounds (III, IV and VI) and 5.0 ppm for compound (V). The mechanism of the reactions was proposed and the analytical parameters were evaluated for both methods. The method was applied for synthetic samples of industrial importance. The recovery was comparable while the sensitivity and detection limits were better for the spectrophotometric detection.

SPECTROPHOTOMETRIC DETERMINATION OF N-HYDROXYMETHYL NICOTINAMIDE

A method for the determination of N-hydroxymethyl nicotinamide by spectrophotometry is described.N-hydroxymethyl nicotinamide was converted to acetate by acid-catalyzed acetylation,followed by base- catalyzed hydroxamation of the acetate ester and color development as the ferric hydroxamate chelate.The resulting colour solution was measured at 524nm,Beer's law is obeyed in the concentration range of 1--8x10^(-3) mol/L N- hydroxymethyl nicotinamide.

Study on the Application of Gibberellin for the Spectrophotometric Determination of Arsenic,Phosphorus,Silicon and Germanium

In the media of 0.66,0.96, 2. 16 and 0.54 mol/L ofH2SO4,the heteropoly acids of As,P.Si and Ge are separately reduced to corresponding heteropoly blues by gibberellin, which exhibit maxirnum absorptions at 835, 820, 810 and 805 nm with molar absorptivities of 2.64x104, 2.54x104 3.51x104 and 2.25x104 L.mol-1'cm-1 and linear ranges of 0-30,0-15,0-10 and 0-30 μg/25mL, The method was applied to the determinations of As, P and Si in alloyed steel.

Catalytic Spectrophotometric Determination of Ultratrace Amounts of Silver with Solubilizing Effect of Nonionic Surfactant

The synthesis and analytical properties of 4,4'-bis(antipyrinyl-4-diazoamino)biphenyl (BAPDAB) were described for the first time. A catalytic kinetic method for thedetermination of silver was proposed. In the presence of Triton X-100 as a solubilizing agent and2,2'-dipyridyl as an activator, silver has a very strong catalytic effect on oxidative decolorationof BAPDAB by persulfate in acetic acid medium. The reaction was followed spectrophotometrically bymeasuring the decrease of absorbance of BAPDAB at 478 nm and 50 ℃. The calibration graphs are ofgood linearity in the range of 8.0 * 10^(-10)-1.0 * 10^(-6) mol/L by a fixed time method. The limitof detection is down to 5.0 * 10^(-10) mol/L. The catalytic reaction is pseudo-first-order withrespect to silver, which in real samples was determined with satisfactory results.

Rapid and simple spectrophotometric determination of persulfate in water by microwave assisted decolorization of Methylene Blue

A rapid and simple method for determination of persulfate in aqueous solution was developed. The method is based on the rapid reaction of persulfate with Methylene Blue（MB） via domestic microwave activation, which can promote the activation of persulfate and decolorize MB quickly. The depletion of MB at 644 nm（the maximum absorption wavelength of MB） is in proportion to the increasing concentration of persulfate in aqueous solution. Linear calibration curve was obtained in the range 0-1.5 mmol/L, with a limit of detection of 0.0028 mmol/L. The reaction time is rapid（within 60 sec）, which is much shorter than that used for conventional methods. Compared with existing analytical methods, it need not any additives, especially colorful Fe2＋, and need not any pretreatment for samples, such as p H adjustment.