Determination Of Methyl Isobutyl Ketone In Urine By Headspace Solid Phase Microextraction Coupled With Gas Chromatography

Objective Methyl Isobutyl Ketone?MIBK?was often used as a solvent and chemical intermediate in many fields.It could be absorbed by the body through inhalation,feeding and percutaneous,causing symptoms of digestive tract irritation and respiratory irritation.Excessive exposure could inhibit and numb the central nervous system of the human body.With the wide application of MIBK,its health hazards had attracted extensive attention.Most of the intermediate metabolites of MIBK were eliminated through converting to carbon dioxide for or incorporated into tissues in vivo,and the remaining2%¹4%of metabolism were excreted in the form of prototype through exhalation and urine.The amount of MIBK in urine could be used as a biomarker for occupational exposure of MIBK.The American Conference of Governmental Industrial Hygienists,the German Deutsche Forschungsgemeinschaft,and the Japan Industrial Hygiene Society have developed or recommended biological contact index of MIBK in the urine at the end of class,which were 1 mg/L,3.5 mg/L,and 1.7 mg/L,respectively.However,there were no biological exposure limit standards and detecting method for biological MIBK been set or developed until now in China.This study developed a method for the determination of MIBK in urine by Headspace Solid-Phase Microextraction Gas Chromatography?HS-SPME-GC?,which would provide technical support for the development of MIBK detection methods and the setting of biological exposure limit standards in China.It has practical significance for protecting the health of people who are exposed to MIBK in work.Methods 1)HS-SPME technology was used in this experiment,the analyte in the gas phase of the headspace bottle was enriched by the extraction head,and then separated from where by capillary column,detected by Flame Ionization Detector finaly,qualitative analysis was done by retention time and quantitative analysis done by peak area ratio between MIBK and the internal standard Cyclohexanone;2)Possible optimization conditions,such as extraction head type,sample volume,extraction temperature,salt effect,extraction time,and GC detection were explored by a series of single factor rotation tests.On the basis of the single factor rotation experiment,the factors that have a greater impact on HS-SPME were selected for the advanced optimization through orthogonal table design experiment,the peak area of MIBK was used as the index for variance analysis to comprehensively select the optimal conditions;3)The accuracy,precision and sample stability of the established method were explored through the methodological performance indicators such as standard addition recovery,standard deviation and the decline rate of the analyte after being saved;4)The developed method was also applied to detect human urine samples and animal metabolic urine samples to further verify the practicability of the method.The uncertainty was evaluated during the experiment for judging and controlling the key influencing factor of uncertainty.Results 1)The results of the single factor rotation experiment of HS-SPME were consistented with the results of the variance analysis of the L₉?3³?orthogonal test.The analyte component in 5.0 mL samplecould be wonderfully extracted with 2.0 grams salting-out agent at 30°C for 30 min by the extraction head of 50/30?m DVB/CAR/PDMS.The chromatogram of GC detection had the best peak shape and the highest response value when DB-5 capillary column was used together with following conditions as 1.5mL/min carrier gas?nitrogen?flow rate,200°C inlet temperature,20:1split ratio is,80°C column temperature,250°C detector temperature,5min desorption,30 mL/min hydrogen flow rate,30 mL/min nitrogen flow rate,and 300 mL/min air flow rate;2)Under the optimized condition,the linear equation was f?x?=2.527x+0.002787,R²=0.9995,with a linear range of 0.05²?g/mL,and adetection limit of 0.006?g/mL;3)The recovery rates of the mixed blank spiked urine samples with MIBK concentrations of 0.05?g/mL,0.5?g/mL,and 2.0?g/mL were 82.7%¹03.7%,and the relative standard deviations were 0.15%⁴.33%.When they were stored in the refrigerator at 4°C and-20°C Within 14 days,the reduction rate of the medium concentration MIBK spiked urine sample were less than 10%;4)0.267⁰.758?g/mL MIBK were detected in their urine samples when 1.0 mg/mL of MIBK solution were administered to the rats through a metabolic cage.The main sources of uncertainty which influence the accuracy of the result values were caused by the standard curve,volume,repeated measurement,HS-SPME and weighing.The extended uncertainty is 0.0942?g/mL.Conclusions 1)HS-SPME was used to pretreat biological samples containing MIBK.This method had the characteristics of no need of organic solvent,simple operation,fast analysis speed and effective reduction of matrix interference.The results of the single factor rotation test were consistented with the results of the orthogonal test on the level of extraction factors,indicating that the experimental optimization was scientific;2)A method for determining MIBK in urine by HS-SPME-GC was established.The method had low detection limit,high sensitivity and high accuracy,good sample stability,and its various indicators meet the requirements of?Guidelines for the establishment of occupational health standards,Part 5:Methods for determination of chemical substances in biological materials??GBZ/T 210.5-2008?;3)The accurate and reliable of the method were verified through the determination of population urine samples and animal urine sample.The main sources of uncertainty were controllable.The method was suitable for determining MIBK in urine samples of occupational exposure of MIBK,and can provide technical support for formulating the biological exposure limit.