| Objective Chromium and manganese are essential trace elements of the human body and have many important physiological functions.However,when the body ingests excessive amounts of chromium and manganese,it will cause harm to the human body.Chromium poisoning can lead to allergic asthma,corrosive gastroenteritis,kidney damage,skin ulcers,nasal septal perforation and lung cancer.Chronic manganese poisoning can cause nervous system disorders,such as limb stiffness and language barriers.Chromium in the body mainly accumulates in the liver,kidney,bone,spleen and lungs.The absorbed chromium is mainly excreted by the kidneys,and urinary chromium can be used as a bio-monitoring indicator for the recent exposure to chromium.The 30?g/g creatinine?in the urine?of chromium was stipulated as biological exposure limit?index?by China and the American Association of Governmental Industrial Physicians?ACGIH?stipulated the biological exposure limit?index?as 25?g/L?end of shift at end of workweek?and10?g/L?during shift?.Most of the manganese in the body is discharged from the feces through the digestive tract,and a small amount is excreted in the urine.When urinary manganese exceeds the normal range,it can be used as a reference indicator for exposure to manganese and diagnosis,and can also be used as an indicator for manganese drive effect.Urinary manganese has been used as an inspection item in occupational health examinations in diagnostic criteria for occupational chronic manganese poisoning?GBZ 3-2006?,but its limits have not been established.Now,the methods for the determination of chromium and manganese in urine are mainly diluting the urine sample with a matrix improver.Then the samples are measuring by the graphite furnace atomic absorption spectrometer directly.The result of the methods is greatly affected by the matrix of the urine sample,and the low concentration urine sample can not be measured.It is only applicable to determination of urine chromium and manganese in exposed people.This study established a method for the determination of chromium and manganese in urine by ionic liquid dispersion liquid-liquid microextraction-graphite furnace atomic absorption spectrometry,which provides a new method for the detection of these two metals in the urine of occupational and non-employee exposed people.Methods The chrome and manganese in urine were detected by graphite furnace atomic absorption spectrometry,which pretreatments were ionic liquid dispersion liquid-liquid microextraction.?1?The pretreatment method of urinary chromium:The methanol,pyrrolidine dithiocarbamate and 1-hexyl-3-methyl-imidazolium hexafluorophosphate were used as extraction solvent,chelating agent and dispersive solvent respectively,for the preconcentration of chromium.The optimal extraction conditions were optimized by single factor rotations,and methodological performance index were tested.?2?The pretreatment method of urinary manganese:The ethanol,8-hydroxyquinoline and 1-octyl-3-methyl-imidazolium hexafluorophosphate were used as extraction solvent,chelating agent and dispersive solvent respectively,for the preconcentration of manganese.The conditions of the chelating agent,dispersant and extractant type and amount,extraction p H,extraction time,eluent dosage,time and so on are explored by the single factor rotation test.Samples were collected for analysis by graphite furnace atomic absorption spectrometry under optimal pretreatment conditions and methodological performance indicators were explored.?3?The sample obtained after extraction was measured by graphite furnace atomic absorption spectrometry.?4?The established method was applied to the determination of urine samples of college student volunteers.A chromium solution with a concentration of 1000?g/L was prepared and used to feed SD rats.The metabolic cage was used to collect urine from rats to determine the chromium content in the urine of rats To further verify the accuracy,precision and practicality of the method.In addition,the uncertainty introduced during the experiment is evaluated to determine the key links that affect the uncertainty.Results?1?The results of urinary chromium:The 3.0 m L of urine sample is added in the digestive tract,and add 1 m L of nitric acid and hydrogen peroxide to a self-controlled electrothermal digester,in order to digest the liquid colorless,which remains about 0.5 m L.Then transfer the liquid to a 10 m L glass centrifuge tube and dilute to 3 mL.After shake well,add 0.6 mL NH3/NH4Cl buffer solution and 670?L[Hmim][PF6]-APDC-CH3OH mixture.After ultrasonication for 25 min,centrifuge at4000 r/min for 5 min,then discard the supernatant and add 200?L of anhydrous methanol to fully dissolve the precipitate.At the last,the sample is injected 10?L into the graphite furnace under working conditions.Under the conditions the linear correlation coefficient of chromium in the range of 0.0?8.0?g/L is greater than 0.99.The detection limit of this method was 0.25?g/L,and the recovery rates were100.6%?104.4%,with the relative standard deviations of 1.12%?7.45%.The urinary chromium concentration of college students'volunteers ranged from 1.78?g/L to11.85?g/L.SD rats were fed with a concentration of 1000?g/L of chromium solution.The urine of the rats was collected in a metabolic cage.Everyday could collecte about 5 mL of urine samples to determine.Doing like this for 10days,the urine chromium concentration range was 7.5?g/L?158.1?g/L.?2?The results of urinary manganese:The 3.0 m L of urine sample is taken in the digestive tract,and add 0.6 mL NH3/NH4Cl buffer solution and 510?L[Omim][PF6]-8-hydroxyquinoline-C2H3OH mixture.After ultrasonication for 10 min,centrifuge at 4000 r/min for 5 min,then discard the supernatant and add 200?L of10%nitric acid.After shaking for 4 min on a vortex mixer,centrifuged at 4000 r/min for 5 min,and the supernatant was injected 10?L into the graphite furnace under working conditions.The linear correlation coefficient of manganese in the range of0.0?1.6?g/L is greater than 0.99.The detection limit of this method was 0.03?g/L,and the recovery rates were 84.90%?96.50%,with the relative standard deviations of0.36%?1.84%.According to the test method,24 urine samples of college students were measured.The results showed that the concentration of urinary manganese in volunteers ranged from 0.20?g/L to 0.44?g/L.Uncertainty was assessed for the 0.5?g/L sample urine sample with an extended uncertainty of 0.0609?g/L.Conclusions?1?A new method for the determination of chromium and manganese in urine by ionic liquid dispersion liquid-microfiltration-graphite furnace atomic absorption spectrometry was established.The method has the advantages of low cost,high enrichment efficiency,high sensitivity and environmental protection.?2?The established method is suitable for the detection of trace chromium and manganese in urine of occupational and non-occupational exposure populations.?3?The indicators of the two methods meet the requirements of the“Guidelines for the establishment of occupational health standards,Part 5:Methods for determination of chemical substances in biological materials”?GBZ/T 210.5-2008?.?4?The feasibility of the method has been verified by detecting the metabolic urine samples from rats and volunteers,which shows that it has practical value and can provide technical support for the determination of trace chromium and manganese in urine. |
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