Rapid Determination of Thiourea in Waste Water by Atmospheric Pressure Chemical Ionization Tandem Mass Spectrometry Using Selected‐reaction Monitoring

Abstract

Thiourea, a toxic substance for nitrification bacteria, active at low concentration levels (toxicity limit: 76 ppb), cannot be analysed by conventional methods. Its high solubility in water and insolubility in non-polar organic solvents, such as diethyl ether or dichloromethane, make its extraction impossible. A rapid method for the direct determination of thiourea in waste water with a minimal sample pre-treatment by atmospheric-pressure chemical ionisation mass spectrometry is presented here. The method takes advantage of tandem mass spectrometry with selected-reaction monitoring so that the system acts as a completely specific detector for thiourea, A detection limit of 1 ppb has been obtained and linear calibration has been determined in the concentration range 10-5000 ppb. The reliability of the method was tested by the analysis of spiked samples, showing good accuracy. The method also proved its ruggedness in the analysis of real samples, giving very good results, despite the complexity of the matrix.

Determination of thiourea in fruit juice by a kinetic spectrophotometric method

“…These are based on direct reflectance spectrometric measurements [23][24][25], Raman spectroscopy [26], mass spectrometry [27], FTIR [28,29], voltammetry [16], potentiometry [30], amperometry [31], titrimetry with iodine [32], potassium dichromate [33] and Masson and Race reagent [34], gas chromatography after benzoylation [35], highperformance liquid chromatography [36], flow injections methods [37][38][39] and kinetic methods [40,41]. Catalytic kinetic spectrophotometric method is a suitable technique for determination of trace levels of thiourea because of its high sensitivity and selectivity and ease of instrumentation.…”

A new and sensitive reaction rate method for spectrophotometric determination of trace amounts of thiourea in different water samples based on an induction period

“…It was clear that the detection limit of the proposed method is better than or comparable with othe reported methods (Toyoda et al 1979, Abbasi et al 2009). Some of these methods have better detection limit than the proposed method (Abbasi et al 2010, Raffaelli et al 1997, but suffer from the expensive equipments (Raffaelli et al 1997)or time consuming (Abbasi et al 2010). …”

“…These problems are due to the existence of a large number of organic components with relatively high concentrations, non-extractable nature of TU with traditional organic solvents and poor volatility of TU, which is not easily analyzed by gas chromatography (Toyoda et al 1979). However, various methods have been proposed for the determination of TU such as titrimetry with iodine (Amin 1985;Pillai and Indrasenan 1980) or Nbromosuccinimdie (Sarwar and Thibert 1968), Raman spectroscopy (Bowley et al 1986), spectrophotometry (Abd El-Kader et al 1984;Hutchinson and Boltz 1958), polarography (Trojánek and Kopanica 1985), voltammetry (Stará and Kopanica 1984), liquid chromatography-mass spectrometry (Xiao-Lan et al 2009), high performance liquid chromatography (Rethmeier et al 2001), ion selective electrode potentiometry (Radić and Komljenović 1991), FTIR (Kargosha et al 2001), and tandem mass spectrometry (Raffaelli et al 1997).…”

Electrooxidation of thiourea and its square-wave voltammetric determination using pencil graphite electrode

“…Normally, it is not present in wastewater; however, it can become a serious problem for industrial wastewater treatment plants which utilizes the bacterial nitrifi cation/denitrifi cation process, especially when the wastewater comes from the industrial complexes. When its concentration of 76 µ g l -1 is exceeded, nitrifi cation bacteria are not able to degrade the ammonia to nitric acid and release of ammonia into the environment occurs (Raffaelli et al 1997 ). Because of the absence of legal regulation limits for TU in wastewaters, the producers of TU-containing wastewater try to reduce its concentration below 1 mg l -1 (Rethmeier et al 2001 ).…”

“…Because of the absence of legal regulation limits for TU in wastewaters, the producers of TU-containing wastewater try to reduce its concentration below 1 mg l -1 (Rethmeier et al 2001 ). Therefore, a fast and reliable method for the determination of TU in wastewater is strongly needed to keep this bacterial inhibitor under control (Raffaelli et al 1997 ). Its high solubility in water and practically insolubility in nonpolar organic solvents make its extraction (e.g., solid-phase extraction) impossible.…”