A Simple Spectrophotometric Method for the Determination of Cadmium in Industrial, Environmental, Biological and Soil Samples Using 5,7-Dibromo-8-hydroxyquinoline

Abstract

Cadmium in trace amounts is important industrially, 1 as a toxicant 2 and biological non-essential, 3 as an environmental pollutant 4 and as an occupational hazard. 5 It is an extremely toxic metal, and has been responsible for a number of deaths. 6 Increasing cadmium pollution of the environment, resulting from the growth of cadmium based industries and the use of fossil fuels, makes the development of a method for the trace and ultra-trace analysis of this toxic metal essential.Spectrophotometry is essentially a trace-analysis technique and is one of the most powerful tools in chemical analysis. 5,7-Dibromo-8-hydroxyquinoline (DBHQ) has been reported to be a spectrophotometric reagent for vanadium 7 and molybdenum, 8 but has not previously been used for the spectrophotometric determination of cadmium. This paper reports on its use in a very sensitive, highly specific spectrophotometric method for the trace determination of cadmium. The method possesses distinct advantages over existing methods 9-11 with respect to sensitivity, selectivity, range of determination, simplicity, speed, pH/acidity range, thermal stability, accuracy, precision, and ease of operation. It is based on the reaction of nonabsorbent DBHQ in a slightly acidic solution (0.00015 -0.00065 M H2SO4) with cadmium to produce a highly absorbent greenish-yellow chelate product, followed by a direct measurement of the absorbance in aqueous solution. With suitable masking, the reaction can be made highly selective, and the reagent blank solutions do not show any absorbance. Experimental ApparatusA Shimadzu (Kyoto, Japan) (Model 160) double-beam UVVisible recording spectrophotometer and a Jenway (England, UK) (Model 3010) pH-meter with a combination of electrodes were used for measurements of the absorbance and pH, respectively. A Shimadzu (Kyoto, Japan) (Model AA6401F) atomic-absorption spectrophotometer equipped with a microcomputer-controlled nitrous oxide-acetylene flame was used to compare the results. Reagents and solutionsAll chemicals used were of analytical-reagent grade or the highest purity available. Doubly distilled deionized water and HPLC-grade absolute ethanol, which is non-absorbent under ultraviolet radiation, were used throughout. Glass vessels were cleaned by soaking in acidified solutions of KMnO4 or K2Cr2O7, followed by washing with nitric acid (1 + 1) and rinsed several times with high-purity deionized water. Stock solutions and environmental water samples (1000 mL each) were kept in polypropylene bottles containing 1 mL of concentrated HNO3. More rigorous contamination control was used when the cadmium levels in the specimens were low. DBHQ solution, 3.3 × 10 -3 MPrepared by dissolving the requisite amount of DBHQ (Merck, Darmstadt, Germany) in a known volume of distilled ethanol. More dilute solutions of the reagent were prepared as required. Cadmium standard solution, 8.89 × 10-3 M A 100-mL amount of stock solution (1 mg mL -1 ) of divalent cadmium was prepared by dissolving 0.2282 mg of A. R. crystallized cadmium sulfate (3C...

Analytical Applications of 2,6‐Diacetylpyridine‐bis‐4‐phenyl‐3‐thiosemicarbazone (2,6‐DAPBPTSC): Determination of Cd(II) in Foods and Water Samples

“…In the present paper, we synthesized a new complexing organic reagent, 2,6-diacetylpyridine-bis-4-phenyl-3thio-semicarbazone for the selective and sensitive extractive spectrophotometric determination of cadmium(II) in foods and water samples. When compared with existed reported methods, [15][16][17][18][19][20][21] the present method is relatively more sensitive (Table 1).…”

Determination of Cadmium in a Municipal Sewage Sludge Based Compost by Spectrophotometric Method/Spektrometrinis Kadmio Kiekio Nustatymas Komposte, Pagamintame Iš Nuotekų Dumblo/Определение Кадмия В Компосте Из Ила Сточных Вод Спектрофотометрическим Метод

“…Sulphuric acid was selected as the best acid for the system in comparison to nitric, phosphoric, hydrochloric (Jamaluddin Ahmed, Tauhidul Chowdhury 2004). The acid is prepared to be 0.0005 M.…”

“…According to the researches, the best absorbance (Fig. 1) is at wavelength of 396 nm (Jamaluddin Ahmed, Tauhidul Chowdhury 2004). The absorbance was done at the wavelength of 396 nm.…”

“…Spectrophotometry is a chemical analysis tool, simple and sensitive to use for the essential trace analyses. The reagent used for the experiment is reported to be a reagent for the investigation of vanadium and molybdenum as well as cadmium (Jamaluddin Ahmed, Tauhidul Chowdhury 2004). The method is based on the reaction of non-absorbent DBHQ with cadmium in slightly acidic solution producing greenish-yellow solution product.…”

Selective Spectrophotometric Determination of Trace Amounts of Cadmium in Soil and Sediment Samples Using a Green Aqueous Biphasic Extraction

“…Determinations of cadmium in soils have been carried out using analytical techniques, such as atomic absorption spectrometry (AAS), [4][5][6][7][8] inductively coupled plasma atomic emission spectrometry (ICP-AES) 9,10 and inductively coupled plasma mass spectrometry (ICP-MS) 10,11 after the extraction of cadmium with acid solutions, such as hydrochloric acid, nitric acid and aqua regia. [4][5][6][9][10][11]13 Although these methods are highly sensitive, they need expensive instrumentations, and involve time-consuming procedures.…”