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Objective:To establish a hydride generation atomic fluorescence method using ammonium persulfate as the digestion reagent for determination of arsenic in urine (hereinafter referred to as this method).Methods:The collected urine samples with ammonium persulfate were heated and digested on the tubular electric heating automatic control constant temperature digester (60 holes), with 5% hydrochloric acid solution as reaction medium and current carrier and 1.5% potassium borohydride solution as reducing agent. Arsenic content was determined with a four-channel atomic fluorescence spectrometer. The arsenic standard solution of 0 - 10 μg/L was prepared to determine the standard curve of this method, and the method was evaluated from the detection limit, linear range, correlation coefficient, precision, standard addition recovery experiment, and urine arsenic quality control sample detection. The standard method "Determination of Arsenic in Urine by Hydride Generation Atomic Fluorescence Spectrometry" (WS/T 474-2015, referred to as the standard method) was used for comparison experiments.Results:When the sampling volume was 1 ml, the detection limit of this method (digest with 1 ml 1.5 mol/L ammonium persulfate) was 0.03 μg/L. In the range of arsenic content from 0 - 10 μg/L, the linear relationship between arsenic content and fluorescence intensity was good, and the correlation coefficients ( r) were all 0.999 9. The relative standard deviations( RSD) of the three replicates of urine samples with different concentrations were 1.00%, 0.89% and 0.49%, respectively. Urine arsenic quality control samples were tested, and the test results were all within the range of public values; the overall average recovery was 102.29%, and the recovery range was 92.10% - 108.15%. Compared with the standard method in the determination results of 20 urine samples, the difference was not statistically significant ( t = - 0.40, P > 0.05). Conclusions:The hydride generation atomic fluorescence spectrometry using ammonium persulfate as digestion reagent for the determination of arsenic in urine has the advantages of low detection limit, good precision, high accuracy, small amount of sampling and digestion reagent, simple operation, and less harmful gas generation in sample pretreatment. It is suitable for rapid determination of arsenic in urine in large quantities.
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Objective:To understand the knowledge and behavior changes of pregnant women on iodine deficiency disorders (IDD) prevention and treatment in iodine deficiency areas in Anhui Province before and after the implementation of the intervention measures, and to provide a scientific basis for pregnant women's iodine nutrition improvement.Methods:From March to December 2018, from Lujiang County, an iodine deficiency area in Anhui Province, Lucheng and Nihe towns were selected as the survey sites. Relying on the township health centers, pregnant women in early pregnancy (≤12 weeks) were selected as the survey subjects, and long-term follow-up was conducted. The edible salt samples of pregnant women in early pregnancy were collected and salt iodine content was detected by direct titration method. The urine samples of pregnant women in the morning in early, middle (13 - 28 weeks) and late pregnancies (≥29 weeks) were collected, urinary iodine content was determined by arsenic-cerium catalytic spectrophotometry. Baseline questionnaire survey was conducted for pregnant women in early pregnancy, mainly including basic information, IDD prevention and treatment knowledge (pregnant women prone to iodine deficiency, the harm of iodine deficiency in pregnant women, suitable iodine supplement methods for pregnant women and foods with high iodine content), and the consumption frequency of iodine-rich foods. After the baseline survey, the knowledge publicity on IDD prevention and treatment was carried out in townships, and iodine-rich foods such as kelp and laver were recommended to supplement iodine. The intervention activities lasted for 6 months, and retrospective questionnaire survey was conducted on pregnant women in late pregnancy.Results:A total of 128 edible salt samples were collected from the families of pregnant women in early pregnancy, and the median salt iodine was 21.5 mg/kg. The iodized salt coverage rate was 99.2% (127/128), the qualified rate of iodized salt was 98.4% (125/127), and the consumption rate of qualified iodized salt was 97.7% (125/128). A total of 129, 95 and 70 urine samples were collected from pregnant women in early, middle and late pregnancies, the medians urinary iodine were 179.0, 185.5 and 189.7 μg/L, respectively, all of which were at the appropriate iodine level. The total awareness rates of IDD prevention and treatment before and after intervention were 22.4% (28/125) and 64.6% (82/127), respectively, and the difference was statistically significant (χ 2 = 45.538, P < 0.01). Compared with the awareness rates before the intervention, the awareness rates of the harm of iodine deficiency in pregnant women, suitable iodine supplement methods for pregnant women and foods with high iodine content were all higher after the intervention ( P < 0.01). There were statistically significant differences in the frequency of eating kelp, laver and other iodine-rich foods among pregnant women in early, middle and late pregnancies (χ 2 = 163.170, 102.373, P < 0.01). Before the intervention, 57 (45.2%) pregnant women had not eaten kelp, which decreased to 1 (0.8%) pregnant woman after the intervention. Before the intervention, 72 (57.1%) pregnant women had not eaten laver and other iodine-rich foods, which decreased to 7 (5.5%) pregnant women after the intervention. Conclusions:After the intervention, the awareness rate of IDD prevention and treatment knowledge and the frequency and proportion of iodine-rich foods consumption among pregnant women in iodine deficiency areas in Anhui Province have increased significantly. It is recommended to carry out publicity and education on IDD prevention and treatment knowledge in early pregnancy.
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Objective:To establish a direct and rapid method for direct determination of arsenic in urine by inductively coupled plasma mass spectrometry (ICP-MS).Methods:The newly collected urine samples were diluted directly with pure water without pretreatment. The total arsenic content in urine was determined directly by ICP-MS. The method was studied from the aspects of linear range of standard curve, correlation coefficient, detection limit, precision and accuracy.Results:The concentration of arsenic in urine was in the range of 0 - 200 μg/L, the ratio of arsenic to germanium was in good linear relationship with arsenic concentration, the correlation coefficient was 0.999 5 - 0.999 9 ( n = 6), the lowest qualitative and quantitative detection limits of arsenic in urine were 0.66 and 1.94 μg/L(the sampling volume was 0.50 ml), respectively. Five urine samples with different arsenic concentrations were tested for intrabatch and inter batch precision with RSD ranging from 1.51% to 6.84% and 1.85% to 5.03%, respectively. The total arsenic of urine samples from the Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention was determined with this method, and the results were within the range of the published consensus value. The recovery rate of 4 urine samples with arsenic concentration range 3.19 - 89.36 μg/L was 99.25% - 103.67%, and the total average recovery rate was 101.51%. Conclusions:Application of ICP-MS method to detect arsenic content in urine, urine samples can be directly injected to realize the automation of injection, detection process and result analysis. The test parameters such as sensitivity, precision and accuracy of the method meet the requirements of the development of biological sample detection method and are suitable for rapid and direct determination of total arsenic in urine.
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Objective:To develop a standard method for determination of iodine in serum by inductively coupled plasma mass spectrometry (ICP-MS).Methods:A direct dilution sampling-ICP-MS method for measuring iodine in serum was developed with 2.0 g/L ascorbic acid-1.0 g/L ammonium chloride-0.10% ethanolamine-1.0% ethanol as diluent; the standard solutions and the serum samples were all diluted in a ratio of 1 : 19 (sample : diluent) before testing with Re as internal standard element. Methodological evaluation of a new method was done through standard curve linearity, sample detection limit, precision and accuracy in determining serum iodine. And the results were compared with the results determined by current standard method for determination of iodine in serum [arsenic-cerium catalytic spectrophotometry, hereinafter referred to as the standard method (WS/T 572-2017)].Results:The following data were obtained by testing the method in six laboratories. The linear range of the calibration curve was 0 - 300 μg/L and the linear correlative coefficients were 0.999 9 - 1.000 0 ( n = 70). The detection limit for serum iodine was 0.2 to 1.3 μg/L (0.20 ml of serum was tested). Precision: the average intra assay coefficient of variation ( CV) was 0.6% with a range of 0.2% - 1.6% when measuring 31 serum samples; the average inter assay CV was 1.3% with a range of 0.3% - 2.4% when measuring 34 serum samples. Accuracy: the average recovery was 100.3% with a range of 93.9% - 105.6% when measuring 36 serum samples. No significant difference was found between the results of the 116 serum samples determined by the new method and the standard method ( P > 0.05). Conclusions:The new method has a good standard curve linearity, high sensitivity, good precision, accuracy and is easy to be used and quickly to be analyzed of the test results, and is suitable for widely application in determining serum iodine.
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Objective:To establish an enzyme-labeled instrument automatic colorimetric method for determination of iodine content in human urine.Methods:The enzyme-labeled instrument automatic colorimetric method was used to determine the iodine content in human urine. The linear range, detection limit and precision of the method were verified. And the urine iodine test results were compared with the results tested by national health industry standard as arsenic-cerium catalytic spectrophotometry.Results:The linear range of iodine standard curve of the enzyme-labeled instrument automatic colorimetric method was 0 - 300 μg/L, the linear correlation coefficient ( r) was - 0.999 5 to - 0.999 2, and the detection limit was 6.5 μg/L. The relative standard deviation ( RSD) of urine samples with low, medium and high iodine concentration were all < 3%, the recovery rate ranged from 92.2% to 109.2%, and the total average recovery rate was 99.6%. There was no significant difference in the detection results of iodine content in 40 urine samples between the enzyme-labeled instrument automatic colorimetric method and arsenic-cerium catalytic spectrophotometry ( t = 1.347, P > 0.05); and the detection speed of the enzyme-labeled instrument automatic colorimetric method was 7.5 times of the arsenic-cerium catalytic spectrophotometry. Conclusion:The enzyme-labeled instrument automatic colorimetric method has a reasonable linear range, good precision and high accuracy in determination of urinary iodine content, and the enzyme-labeled instrument automatied fast colorimetry has improved the analysis speed, it is suitable for detection of large quantities of samples.
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Objective:To establish an automatic colorimetric method for determination of iodine in drinking water by enzyme-labeled instrument (hereinafter referred to as this method).Methods:The water iodine was measured in the range of 0 - 10 μg/L and 0 - 100 μg/L, experiments were carried out on linear relationship, detection limit, precision and accuracy of this method. And the results were compared with the National Reference Laboratory for Iodine Deficiency Disorders recommended arsenic cerium catalytic spectrophotometry method.Results:In the range of 0 - 10 μg/L and 0 - 100 μg/L, all│ r│ > 0.999 0, the detection limits were 0.6 and 1.1 μg/L (samples were 200 and 100 μl), respectively; the relative standard deviation ( RSD) of water samples of low, medium and high iodine mass concentrations were < 3%, the recovery rates ranged from 92.5% to 108.3% and 93.2% to 108.9%, with a total average recovery of 100.0% and 100.3%, respectively. This method and arsenic cerium catalytic spectrophotometry method were used to detect 40 water samples in the range of 0 - 10 μg/L and 0 - 100 μg/L, there was no significant difference in water iodine content between the two methods ( t = 0.99, P > 0.05). Conclusion:This method has good linear curve relationship for determination of water iodine content, good precision and high accuracy, and it is suitable for wide application.
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Objective To verify the feasibility and application value of arsenic-cerium catalytic spectrophotometry for determination of iodine in serum.Methods The blood samples of adults were collected and the iodine standard curve of 0-300 μg/L was prepared.Referring to "The Method for Determination of Chemical Substances in Biomaterials",the present method was tested in terms of linear relationship,minimum detection limit,precision and accuracy.Results The correlation coefficient of the method was-0.999 7--0.999 4 (n =6) and the minimum detection limit was 5.13 μg/L in the range of 0-300 μg/L standard curve.Precision verification displayed that the variable coefficient of three different iodine concentration serum samples were 0.89％,1.88％,0.67％.And the accuracy verification displayed that the recovery of iodine standard was 93.90％-107.04％,and the total average recovery was 99.48％.Conclusion The method has been proved to be of good linearity,high precision and high accuracy in the determination of serum iodine,which meets the requirements of biological sample analysis.
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Objective To determine serum iodine by inductively coupled plasma mass spectrometry (ICP-MS).Methods ICP-MS was used to determine iodine content directly by pretreatment method of diluting serum samples and standard series with diluent.The method was tested from correlation coefficient of standard curve,detection limit,precision,accuracy,etc.Results When the concentration of iodine in serum ranged from 0 to 300 μg/L,the linear correlation coefficient with the iodine ion counts determined by the instrument was 0.999 8 to 1.000 0 (n =6);the detection limit of iodine in serum was 1.24 μg/L;the relative standard deviation (RSD) ranged from 0.5％ to 1.5％ and from 0.3％ to 1.4％ for the intra-and inter-batch precision tests of seven different serum samples,respectively;the recovery rate of 7 serum samples with iodine content 40-230 μg/L ranged from 93.4％ to 109.2％,and the total average recovery rate was 102.4％.Conclusions Serum samples need not be pretreated before digestion,and can be directly injected after dilution with diluent without using highly toxic substances.The detection process is automatic,sensitive,precise,accurate and suitable for rapid quantitative determination of serum iodine content.
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Objective To explore the iodine nutritional status of people after adjusting iodine content in iodized salt in Anhui Province. Methods In 2014, 30 counties (cities, districts) were selected in Anhui Province according to the probability ratio sampling method (PPS), and one school was selected in each county (city, district), and 50 children aged 8 - 10 years were selected in each school. Urine and household salt samples were collected, urine and salt iodine levels were tested, and thyroid was examined using B-ultrasound. In the township where the school was located, 20 pregnant women's urine samples and household salt samples were collected for urine and salt iodine detection. The salt iodine level was measured by direct titration, Chuan salt and other fortified salt iodine levels were determined by arbitration method (GB/T 13025.7-2012). Urinary iodine was determined by arsenic-cerium catalytic spectrophotometry (WS/T 107-2006). Results A total of 1575 children's household salt samples were collected, the median salt iodine was 23.77 mg/kg, the qualified iodized salt consumption rate was 93.65％(1475/1575); 600 household salt samples were collected from pregnant women, the salt iodine median was 23.50 mg/kg, the consumption rate of qualified iodine salt was 96.33％( 578/600 ) . A total of 1575 urine samples were collected from children, the median urinary iodine was 242.20 μg/L; six hundred urine samples were collected from pregnant women, and the median urinary iodine was 158.15μg/L, 43.33％(13/30) of the counties (cities, districts) pregnant wowen median urinary iodine < 150 μg/L. A total of 1575 thyroid glands were examined in children aged 8 to 10 years, and the thyroid enlargement rate was 3.75％ (59/1575). Conclusion The iodine nutrition of children aged 8 - 10 years in Anhui Province is higher than the appropriate level, but the iodine is not in the excessive state, and the iodine nutrition of pregnant women in some counties (cities, districts) is insufficient.
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Objective To establish a method for automatic determination of iodine content in drinking water by flow injection analysis (FIA) without arsenic. Methods In the dilute nitric acid solution, iodide ion in appropriate amount of nitrous acid solution could catalyze the orange red iron thiocyanate complex fade, and the use of this method combined with flow injection analysis technology formulated a flow injection method, and experimental conditions of the method were optimized. The linear relationship and linear range of the standard curve, the detection limit, the precision and the accuracy of the sample determination were implemented under the optimized conditions. Results The optimum concentration of potassium thiocyanate solution (0.15 mol/L) and sodium nitrite was 27.30 ml and 8.00 g/L, respectively, by series of experimental studies. Under the condition, the linear range of the standard curve was 0-500μg/L, the standard curve linear relationship coefficient≥0.9990;method detection limit was 5.94μg/L; in precision experiment of low, medium and high concentrations of iodine, the coefficients of variation were 1.19%, 1.92%and 2.06%;in accuracy test, recovery rates were 100.49%-107.84%, and the total recovery rate was 103.15%. Conclusions The flow injection analysis method can be used to replace arsenic cerium catalyzed spectrophotometric detection of iodide in water; when the method is used in detection of the sample water iodide content of 0 - 500 μg/L, it has good precision and accuracy, automatic injection, automatic filling reagents and automatic detection system to reduce the burden on the staff, with arsenic-free reagents and reduced environmental pollution and the health hazards of the inspectors, which is suitable for iodine screening in high iodine areas.
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Objective To establish a method for determination of urinary iodine by an automatic biochemical analyzer,and to analysis the applicability on the detetion of iodine deficiency disorders.Methods An automatic biochemical analyzer was used to determine urinary iodine content.Linear range,detection limit,precision,recovery and so on were studied.Results The linear range was 0-300 μg/L;the detection limit was 1.57 μg/L (600 μl sample);the relative standard deviations (RSD) were 1.30％,0.83％ and 1.05％ when measuring urine samples with iodine concentrations of (84.8±1.1),(156.5 ± 1.3) and (227.7 ± 2.4)μg/L,respectively;the average recovery was 98.0％,100.1％ and 98.6％,and the total average recovery was 98.9％,when measuring urine samples containing three different iodine concentrations.The test results of standard material were all within the required ranges.The difference of measuring 24 urine samptes in the field by this method and the standard method was not statistically significant by paired t test (t =0.35,P ＞ 0.05).Compared with standard method,the amount usage of arsenic trioxide was reduced to 2％ (0.50 to 25.00 mg per sample).Conclusions The method has theadvantages of simple operation,low requirement for environment,and the linear rang of detection is reasonable.Using this method,the usage of highly toxic reagent can be greatly reduced,as well as the risk of harm to personnel health and the level of environment pollution.The standard solution and reagents can be prepared by ourselves,which greatly reduces the costs.With short reaction time,high detection speed and measuring automatically for large numbers of samples,this method for determination of urinary iodine by an automatic biochemical analyzer can be applied in monitoring of iodine deficiency disorders.