A Selective and Sensitive Method for the Determination of Molybdenum in High Grade Pipeline Steels

Abstract

Pipeline system is the main form of transportation for oil and natural gas. High grade pipeline steel can effectively improve the security of long-distance transportation and to reduce costs, will become the main steel for gas pipeline project. A highly selective and sensitive spectrophotometric method for the determination of molybdenum in high grade pipeline steel has been presented. This method was based on the chromogenic reaction between molybdenum(V) and sodium thiocyanate. Employing stannous chloride as a reductant, molybdenum(VI) was reduced to molybdenum(V) at the room temperature. The obtained molybdenum(V) formed an orange-red-colored (1:5) ligand complex with thiocyanate. The absorbance of the complex was measured at 470nm, and the molar extinction coefficient (e) is 1.75´104L·mol-1·cm-1. Under the optimum reaction conditions the absorption value was proportional to the concentration of molybdenum in the range of 0.11%~0.89% (mass fraction), and the relative standard deviation was less than 3.0%. The proposed method was free from the interference from a large number of analytical important elements and has been applied satisfactorily to the determination of molybdenum in X80 pipeline steel and X70 pipeline steel samples with the improved accuracy and precision.

Chemical Modified Carbon Paste Electrode for Potentiometric Determination of Mo(VI) and its Application in Food Analysis and Agriculture Fertilizers

“…This study involves potentiometric determination of molybdenum (VI) in agricultural fertilizer. For the analysis of molybdenum, some methods have been recorded such as high-performance liquid chromatography (HPLC) [6][7][8], high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) [9,10], spectrophotometric [11,21] and voltametric methods [22][23][24][25][26][27][28][29]. Several instrumental methods, such as AAS, ICP and strip voltammetry are employed for the determination of molybdenum at low concentration level.…”

A spectrophotometric method for determination of molybdenum in water samples by using pyrogallol red and a water soluble ionic liquid

“…Spectrophotometric methods occupy a special position due to their simplicity and inexpensive instrumentation with reasonable sensitivity. A literature survey reveals that many reagents have been employed for determination of Mo(VI) ions at trace levels such as 2,3,4-trihydroxy acetophenone phenylhydrozone, 17 thionine, 18 6-(5-chloro-2-hydroxy-4-sulfophenylazo)-5-hydroxy-1naphthalenesulfonicacid, 19 7,8-dihydroxy-4-methylcoumarin, 20 gallacetophenone phenylhydrazone, 11 resacetophenone p-hydroxybenzoylhydrazone, 21 thiocyanate, 22 and triphenyltetrazolium. 23 However, most of them have reported low sensitivity with molar absorptivity less than 4 Â 10 4 L mol À1 cm À1 and in some instances do not have the necessary selectivity which requires an extraction step prior to the analysis.…”

“…23 However, most of them have reported low sensitivity with molar absorptivity less than 4 Â 10 4 L mol À1 cm À1 and in some instances do not have the necessary selectivity which requires an extraction step prior to the analysis. 11,19,22 It is well known that the addition of surfactant substances improves the selectivity and sensitivity of the methods developed for determination of metal complexes due to their bathoand hyperchromic effects. 24 Surfactant micelles can bring about changes in solubility, acidity, reaction rates and mechanisms, spectral distributions and intensities.…”