A simple method for detecting fenitrothion, its metabolite 3-methyl-4-nitrophenol, and other organophosphorus pesticides in human urine by LC-MS

Abstract

acute OP poisoning is most commonly encountered in emergency or forensic medicine [2,3]. The majority of such cases are attempts of suicide; in Japan, the OP compound most commonly used for this purpose is fenitrothion, followed by malathion and dichlorvos [4].Fenitrothion is categorized as a "moderately hazardous compound" (WHO class II) and is extensively used in many countries, including Japan, Canada, and Australia [3,5]. Although its oral toxicity in rats is low, fenitrothion poisoning is often life threatening or fatal in humans [6,7]. The authors have recently developed a rapid and reliable liquid chromatography-mass spectrometry (LC-MS) method for detection of OPs, including fenitrothion, in human serum [8], and have reported that serum fenitrothion concentration is useful in predicting the severity and outcome of fenitrothion poisoning [9]. OPs, however, are rapidly metabolized in the human body, suggesting that in most cases, the monitoring of parent compounds in blood is not reliable. In contrast, urinary concentrations of OPs and/or their metabolites are usually higher than the serum levels, and are probably detectable for longer periods of time [10].Dialkylphosphates, the major metabolites of OPs, have been determined in urine samples using gas chromatography (GC) [11,12], GC-MS [13-15], GC-MS-MS [16,17], and LC-MS-MS [18-20]. Their extraction procedures, however, are complicated and not specifi c for each OP [17].3-Methyl-4-nitrophenol (MNP) is a specifi c metabolite of fenitrothion. A method was developed for detection of both fenitrothion and MNP in serum and urine by high-performance liquid chromatography (HPLC) [21], but the validation of the analysis of fenitrothion and MNP has not been studied.Abstract A simple liquid chromatography-mass spectrometry (LC-MS) method was developed and carefully validated for quantitation of fenitrothion, its metabolite 3-methyl-4-nitrophenol, and fi ve other organophosphorus pesticides (acephate, cyanophos, methidathion, ethyl p-nitrophenyl phenylphosphonothioate, and malathion) in human urine samples. Following deproteinization by acetonitrile, the extracts were injected into an LC system and quantitated by MS in the negative ionization mode. The limits of detection were in the range of 0.25-0.75 μg/ ml for each analyte, and the method was validated on its accuracy and precision over the concentration range of 1-15 μg/ml. The method was successfully applied to an actual poisoning case and should prove useful in clinical and forensic toxicology.

Pattern of poisoning in Japan: selection of drugs and poisons for systematic toxicological analysis

“…Pattern of poisoning in Japan This result seems to be related to an aspect of Japanese culture, in which pesticides are chosen as a means of suicide [5]. This pattern is totally different from those in the UK, Germany, Iran, and Nordic countries [6][7][8][9], but similar to those reported in Greece, India, South Korea, and Uganda [10][11][12][13].…”

Rapid Separation of Organophosphate Pesticides using Micellar Electrokinetic Chromatography and Short‐end Injection,

“…3). These results significantly improved the separation speed from other methods that described in the literature (29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(48)(49)(50). Table 2 further illustrates this achievement and compares how other analytical techniques such as GC, LC, and MEKC (long-end injection) performed with respect to the MEKC (short-end injection).…”

“…In GC analysis, they were commonly separated using GC‐mass spectrometry (MS) and GC with flame photometric detector (FPD) . In LC analysis, high‐performance liquid chromatography (HPLC) coupled with UV‐Vis (UV) detector and MS were commonly used.…”

Advances in Analytical Methods for Organophosphorus Pesticide Detection

“…Analysis takes place in either positive (PI) or in negative (NI) ionization mode (Barcelo et al, 1993;Lacorte & Barcelo, 1995 (Barcelo et al, 1993;Lacorte & Barcelo, 1995). LC-MS instruments with APCI have been widely utilized for trace detection of OP levels in a range of samples from the environment (Ingelse et al, 2001;Schreiber et al, 2000;Slobodnik et al, 1996) to agriculture (Mol et al, 2003;Titato et al, 2007) and biological specimen (Inoue et al, 2009), due to APCI's lack of signal suppression from matrix components. Ingelse et al demonstrated APCI usefulness for detecting very polar OP pesticides in water (Ingelse et al, 2001).…”