Studies On The Enrichment And GC Determination Of Urinary Metabolites Of Four Organic Compounds

N-hexane, benzene, toluene, nitrobenzene and other organic compounds are widely used as the most common organic solvents in the fields of industrial and scientific fields. The human body exposure to these harmful substances through inhalation or skin may cause a certain level of damages to human health. The harmful substances are metabolized by the body and transformed into their corresponding metabolites in urine, blood and other biological materials, which could be quantitatively detected. The metabolites in urine of the four compounds aforementioned are2,5-hexanedione, phenol, o-cresol and p-nitrophenol, respectively. With the sociological development, professional harm and prevention caused more and more people’s attention. By means of monitoring the urinary metabolites of the toxic and harmful substances, it could objectively give the level of intoxication of the organism who contact harmful substances, and it also could provide the important basis for occupational poisoning diagnosis and treatment. Nevertheless, there has not a mature method for the simultaneous determination of metabolites of a variety of harmful substances in urine been developed, meanwhile, there is not the background value and samples library about metabolites in urine of the normal population. As a result, it is quite necessary to develop an analytical method for the determination of urinary metabolites of harmful substances.In this stuty, a capillary gas chromatographic method (GC) was established for the simultaneous determination of the four urinary metabolites. The chromatographic separation and determination conditions were optimized by investigating the influence of column type, column temperature, injection way, injection volume, carrier gas flow rate, inlet pressure etc on the separation and detective situation of four components. The optimal conditions were: DB-1MS column (15m×0.53mm×0.50μm) for separation, the temperature program adopted from60℃to140℃(maintaining2min) in25℃/min; nitrogen as the carrier gas (20mL/min) and up gas (11.7mL/min), the hydrogen flow rate of43.4mL/min and the air flow rate of430mL/min. The injector type was splitless sampling and the injection volume is1.6μL. The injector temperature was260℃, and FID detector temperature was300℃. Under the optimal chromatographic conditions, the four components could be well separated and simultaneously detected in5min, the established method was appropriate for the simultaneous separation and detection of four urinary metabolites of harmful substances.Two pretreatment methods of dispersive liquid-liquid microextraction (DLLME) and solid phase extraction (SPE) were established for the simultaneous extraction and enrichment of the four urinary metabolites. The optimal pretreatment conditions of two pretreatment methods were obtained by optimizing the experimental parameters. For the dispersive liquid-liquid microextraction,150μL dichloromethane was used as the extraction solvent,0.6mL isopropanol as dispersive solvent, the extraction time was6min and the urine’s pH was about6, the dosage of NaCl was0.2g. Also, the optimal conditions for solid phase extraction was determined, ProElut C18was used as the stationary phase, the sample volume was25mL and the pH of urines was about6, dichloromethane-tetrachloroethane (v:v=17:3) as extraction solvent and the extractant volume was0.5mL.Under the optimum conditions of DLLME-GC and SPE-GC, the working curves which were used for the quantitative analysis of the four urine metabolites were established respectively. The correlation coefficients were ranged from0.9990-0.9999, linear ranges were0.01～8.3μg/mL. For the DLLME-GC, the enrichment factors were between19and31, the detection limits were0.002～0.2μg/mL (S/N=3). The average recoveries in urine samples were86.7～105%and the relative standard deviations were3.1%～5.0%. For the SPE-GC, the enrichment factors were from14to42, the detection limits were0.002～0.4μg/mL (S/N=3). The average recoveries in urine samples were88.2～108%and the relative standard deviations were3.0%-4.9%.The results showed that the two established methods of DLLME-GC and SPE-GC for the simultaneous determination of the four urinary metabolites of harmful substances were simple, rapid, sensitive, accurate and environment-friendly. The analytical method can meet the needs of biological monitoring work on the urinary metabolites of harmful substances.