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Objective:To learn about the iodine nutritional status of children aged 8 to 10 years in Xiamen City after the reform of salt industry system, and to provide scientific basis for reasonable prevention and control of iodine deficiency disorders.Methods:From 2017 to 2019, 6 districts were selected each year in Xiamen City 5 sampling districts were divided according to the oriation of east, west, south, north and center in each district. One town (street, hereinafter refered as to town) was selected from each sampling district. One primary school was selected from each town. For each primary school, at least 40 non-boarding children aged 8 to 10 years (age balanced, half male and half female) were selected. Edible salt samples in the households and random urine samples of children aged 8 to 10 years were collected, and salt iodine and urinary iodine contents were measured, while thyroid volume was examined by B-ultrasound.Results:From 2017 to 2019, the coverage rate of iodized salt in Xiamen City was 97.34% (1 206/1 239), 96.89% (1 214/1 253), and 93.33% (1 175/1 259), respectively; the consumption rate of qualified iodized salt was 96.13% (1 191/1 239), 95.61% (1 198/1 253), and 91.58% (1 153/1 259), respectively; the median urinary iodine was 182.90, 182.81, 164.00 μg/L, respectively. The prevalence of goiter of boys and girls was 1.01% (19/1 889) and 2.26% (42/1 862), respectively.Conclusions:After the reform of salt industry system, the iodine nutritional status of children aged 8 to 10 years is generally at an appropriate level in Xiamen City. However, the consumption rate of qualified iodized salt is reduced, which increases the risk of iodine deficiency for residents. Therefore, we should strengthen the propaganda of scientific iodine supplement, maintain a high consumption rate of qualified iodized salt, and prevent the harm of iodine deficiency.
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At present, due to the opening and circulation of salt market, potassium iodate iodized salt, potassium iodide iodized salt, seaweed iodized salt and non-iodized salt may exist simultaneously in the edible salt market of a region, which brings new problems to the work of testing iodine content of edible salt in the laboratory. In order to carry out salt iodine detection for prevention and monitoring of iodine deficiency disorders, this paper introduces some methods which established by the author for a rapid qualitative, semi-quantitative and quantitative detection of iodized salt of different forms of iodine and non-iodized salt. And further application and discussion of the methods are described for reference of iodized salt monitoring.
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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 investigate the iodine nutritional status among children aged from 8 - 10 and pregnant women in Xiamen City before and after adjustment of salt iodine concentration, and scientifically evaluate the suitability of the new standard iodized salt adjustment policy for Xiamen City.Methods:In the pre-adjustment period (2011) and the post-adjustment period (2018), cross-sectional research methods and stratified cluster sampling methods were adopted in six districts of Xiamen City. The salt samples of residents and pregnant women, urine samples of children aged from 8 - 10 and pregnant women were collected to determine the iodine level; thyroid of children aged from 8 - 10 was examined. Changes in salt iodine, urine iodine and goiter prevalence before and after adjusting iodine content of salt were compared.Results:The median of salt iodine in residents after the adjustment (23.5 mg/kg) was significantly lower than that of before (28.9 mg/kg, Z = - 10.512, P < 0.05), the median of salt iodine in pregnant women after the adjustment (23.7 mg/kg) was significantly lower than that of before (29.2 mg/kg, Z = - 12.622, P < 0.05); the consumption rate of qualified iodized salt in residents after the adjustment (95.7%, 1 196/1 250) was significantly lower than that of before (97.1%, 1 608/1 656; χ 2 = 4.250, P < 0.05); before and after adjustment of salt iodine concentration, the consumption rate of qualified iodized salt in pregnant women was 94.7% (124/131) and 95.9% (579/604), respectively. No significant difference was found when comparing the consumption rate of qualified iodized salt in pregnant women (χ 2 = 0.015, P > 0.05). There was significant difference in median urinary iodine (from 204.2 to 183.9 μg/L, detected in 652, 1 250 urine samples, respectively) of children aged 8 - 10 years ( Z = - 3.583, P < 0.05); the difference of iodine nutritional status in pregnant women before and after adjustment of salt iodine concentration(130.2, 130.8 μg/L, detected in 132, 604 urine samples, respectively) was not significant ( Z = - 1.715, P > 0.05). The thyroid goiter rate of children aged 8 - 10 years had reduced from 1.1% (14/1 239) to 0.2% (2/1 253), the difference was statistically significant (χ 2 = 9.195, P < 0.05). Conclusions:As a whole, the measure of control and prevention of iodine deficiency disorders through iodized salt is implemented well in Xiamen City. After adjustment of salt iodine concentration, the iodine status of children aged from 8 to 10 is adequate, but the pregnant women has showed iodine deficiency.
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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 screen a suitable reagent system for measuring iodine in serum by direct dilution sampling-inductively coupled plasma mass spectrometry (ICP-MS).Methods Experiments were on sample dilution method for standard solutions and serum samples with six different diluents.After dilution,the concentration of iodine in serum was determined by ICP-MS method.The rhenium (Re) and tellurium (Te) was used as internal standard element,respectively.The effects of the two internal standard elements on determination results were compared.And the results were compared with the results determined by the current serum iodine arsenic cerium catalytic spectrophotometry standard method (WS/T 572-2017),hereinafter referred to as the standard method.The methodological evaluation of this new method was done through standard curve linearity,sample detection limit,precision and accuracy in determining serum iodine in the range of 0-300 μg/L.Results The direct dilution sampling-ICP-MS method screened for measuring iodine in serum was preparing 1 L of 2.0 g/L ascorbic acid,1.0 g/L ammonium chloride,0.10％ ethanolamine,and 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.The linear range of the calibration curve was 0-300 μg/L and the linear correlative coefficient was 0.999 9.The detection limit for serum iodine was 1.2 μg/L (0.20 ml of serum was tested).Precision:the range of the intra assay coefficient of variation (CV) was 0.2％-1.2％ (n =6) and the range of the inter assay CV was 0.4％-1.9％ (n =3) when measuring 5 serum samples.Accuracy:The average recovery was 97.9％ with a range of 93.9％-103.8％ when measuring 8 serum samples.No significant difference was found between the results of the 35 serum samples determined by the standard method and the new method (t =0.178,P ＞ 0.05).Conclusions Re performs better than Te in determination of iodine as an internal standard element.The reagent system screened for determination of iodine in serum does not require matrix matching.This method has good standard curve linearity,high sensitivity,good precision,accuracy and anti-interference ability,and is easy to be used and quickly to be analyzed of the test results,which is suitable for widely application in determining serum iodine.
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Objective To establish a catalytic spectrophotometric method for determination of iodine in water without the use of highly toxic arsenic reagents with good precision and accuracy.Methods A new flow injection catalytic spectrophotometry method for determination of iodine in water was established by combining flow injection analysis (FIA) with a new catalytic spectrophotometry for determination of iodine with no need of arsenic reagent.The standard curve linearity,sample detection limit,precision and accuracy of different iodine content ranges (0-250,0-1 200 μg/L) were tested.The test result was compared with that of the arsenic-based catalytic spectrophotometry recommended by the iodine deficiency disorders monitoring program in China (recommended monitoring method).Results A calibration relation of C =aA2 + bA + d (C:iodine concentration,A:measuring absorbance peak area from FIA) of the new method existed in the range of 0-250 and 0-1 200 μg/L.The linear correlative coefficient were both 0.999 9.The detection limit for iodine in water was 0.3 μg/L.The FIA peak shape of the sample tube with the lowest content is determined,and the sensitive iodine signal is detected.The water samples with different iodine content ranges were determined in parallel for 6 times,and the coefficient of variation (CV) was 0.2％-2.7％;the recoveries ranged from 95.0％ to 105.0％,and the total average recovery was 100.3％.The measured values of water iodine standard material GBW 09113e [(8.2 ± 1.2) μg/L] and GBW 09114d [(62.0 ± 6.0) μg/L] in the standard curve of different iodine contents were all within the uncertainty range of the given value.There was no significant difference between the results of recommended monitoring method and the new method (t =0.781,P ＞ 0.05).Conclusions The new method for measuring water iodine has a wide standard curve range,high sensitivity,and good precision and accuracy.The instrument is easy to operate,and no need for toxic arsenic reagent.The method is a reliable method for water iodine detection.
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Objective To establish a catalytic spectrophotometric method for determination of iodine in urine without the use of highly toxic arsenic reagents and with good precision and accuracy. Methods Combined flow injection analysis (FIA) with new catalytic spectrophotometry, a new method for determination of iodine with no need of arsenic reagents was developed by the author. An ammonium persulfate digestion-flow injection catalytic spectrophotometry for determination of iodine in urine was established. Standard serial solutions and urine samples were all digested by ammonium persulfate before testing. The standard curve linearity in the range of 0-1200μg/L, detection limit,precision and accuracy in determining urinary iodine were tested. Results A good calibration relation of C=aA2+bA+d (C:iodine concentration,A:measuring absorbance peak area from FIA) of the newly developed method existed in the range of 0 - 1200 μg/L. The linear correlative coefficient was 0.9998. The FIA analysis speed was 60 samples per hour. The detection limit for urinary iodine was 7.1μg/L. Precision:The intra-assay coefficients of variation (CV) were 0.3％ - 3.0％ (n = 6) when measuring 9 urine samples with iodine concentration of 61.8-806.8μg/L;the intra-assay CV were 0.2％-1.7％(n=6) when measuring 5 urinary iodine national standard materials with iodine concentration of 76.9 - 883.0 μg/L; the inter-assay CV were 1.0％ - 1.2％ when measuring 6 batches of 3 urinary iodine national standard materials with iodine concentration of 76.9 - 232.0 μg/L. Accuracy:The average recovery rate was 98.3％ with a range of 91.2％ - 104.6％ when measuring 20 urine samples with iodine concentration ranged from 18.9 to 807.1 μg/L. The test results of 5 urinary iodine national standard materials were all within the given value range and the relative deviations ranges were-2.9％-0.7％. No significant difference was found between the results of the 48 urine samples determined by the current standard method (WS/T 107.1-2016) and the new method (t=0.029, P>0.05). Conclusions The new method has a wide standard curve range, high sensitivity, good precision and accuracy, and is simple and easy to operate, with automatic sampling, rapid analysis, and no need for toxic arsenic reagent which is difficult to obtain and can pollute the environment. The method is suitable for widely application and can be used as a reliable technical method for urinary iodine detection.
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Objective To screen the suitable sample digestion method for measuring iodine in serum by arsenic cerium catalytic spectrophotometric method , and to carry out the methodology test for the newly developed arsenic cerium catalytic spectrophotometry for determination of iodine in serum .Methods Methodology evaluation.Experimentswere on the sample on the sample digestion method of serum iodine with several common digestive agents . After digestion treatment , the concentration of iodine in serum was determined by arsenic cerium catalytic spectrophotometry .The linearity and linear range of the standard curve, detection limit, precision, recovery rate and anti -interference ability of the newlydeveloped arsenic cerium catalytic spectrophotometry were tested .Results Sample pretreatment method included in the newly developed arsenic cerium catalytic spectrophotometry was selected as follows: perchloric acid -sodium chlorate solution was used as the digestive agent to digest 120 min at 130℃.The calibration relation of C =a+blgA( C: iodine concentration ,A: measuring absorbance ) of the newly developed method existed when arsenic ceriumcatalytic reaction was kept at a certain stable temperature range from 13℃ to 30℃ and in certain stable reacting time .The linear range of the calibration curvewas 0 -300 μg/Land the linear correlative coefficient was -0.9996 --0.9999.The intra assay coefficients of variation ( CVs ) were 0.70%,0.70%and 0.74%(n=6), and the inter assay CVs were 0.57%, 0.51% and 0.57% (n=6) for 3 serum samples.The average recovery was 97.9% with a range from 92.3% to 105.8% for 3 serum samples.Conclusions The newly developed arsenic cerium catalytic spectrophotometry has good precision and accuracy .The sample digestion agent is easy to be prepared and reserved , and the instrument is simple and easy to be operated .The method can be widely used as a reliable technique for measuring iodine in serum.
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Objective To establish a catalytic spectrophotometric method for determination of iodine in water using the same arsenious acid solution and ceric ammonium sulfate solution as those used in the 2016 version standard method for determination of urinary iodine,and to meet the needs of wide concentration range of water iodine detection.Methods After pretreatment of the water sample with the effective chlorine of sodium dichloroisocyanurate solution for eliminating the interference of reducing substances at room temperature,the concentration of iodine in water was determined by arsenic cerium catalytic spectrophotometry using the same 0.025 mol/L arsenious acid solution and 0.025 mol/L ceric ammonium sulfate solution as those used in the 2016 version standard method for determination of urinary iodine.The linear relationship of the standard curve and the linear rang of different iodine concentration range (0-100,0-400,0-800μg/L),the detection limit,the precision and the accuracy of the sample were tested.Results The calibration relation of C =a + blgA (C:iodine concentration,A:measuring absorbance) in the new method existed when arsenic cerium catalytic reaction was kept at a certain stable temperature ranging from 15 ℃ to 30 ℃ in certain stable reacting time.The linear correlative coefficients absolute value of different iodine concentration range (0-100,0-400,0-800 μg/L) were all greater than 0.999 0,corresponding to the water iodine detection limits were 0.3 μ,g/L (sample volume of 0.80 ml),1.2 μg/L (sample volume of 0.20 ml),and 2.2.μg/L (sample volume of 0.10 ml),respectively.The coefficients of variation (CV) of the three different iodine concentration range were all below 1.0％ (n =6).The iodine recovery rate range of a total of 10 different water samples in these three different concentration range was 95.8％-98.7％,98.3％-103.7％ and 98.5％-104.5％,and the average recovery rate was 97.6％,100.4％ and 102.4％,respectively.In the range of these three different standard curves,water iodine standard materials GBW09114c,GBW09114a and GBW09113c were measured.The relative errors between the results and the given values were ＜ 3.0％,which were in the range of uncertainty of the given value.Conclusion This method verified by methodology experiments has wide linear range,high precision,accuracy,and anti-interference ability,good reproducibility,and is easy to operate,with reduced amount of arsenic waste,reduced environmental pollution,and is suitable for application in different areas to determine water iodine.
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Objective To establish a method for determination of iodine in urine with no need for base urine match by inductively coupled plasma mass spectrometry (ICP-MS).Methods The diluent which contains 2.5 g/L N2H4·2HCl-1.0 g/L NH4C1-0.50％HC1-2.0％C2H5OH were used to eliminate the matrix interference in determination of iodine in urine by ICP-MS.The standard solutions and the urine samples were all diluted in a ratio of 19:1 (diluents:sample) before testing.The methodological evaluation of this new method was done through standard curve linearity,sample detection limit,precision and accuracy in determining urinary iodine.And the determine results were compared with the current urinary iodine arsenic cerium catalytic spectrophotometry standard method (WS/T 107.1-2016,hereinafter referred to as the standard method).Results The linear range of the calibration curve was 0-1 000 μ.g/L and the linear correlative coefficient was 0.999 9.The detection limit for urinary iodine was 0.4 μg/L (0.25 ml of urine was tested).Precision:The average coefficient of variation (CV)was 0.8％ with a range of 0.2％-1.7％ (n =6) when measuring 33 urine samples with iodine concentration of 26.5-854.4 μμg/L.Accuracy:The iodine standard of 40-400 μg/L was added for recovery test.The average recovery was 99.6％ with a range of 94.3％-103.4％ when measuring 24 urine samples with iodine concentration of 26.5-858.3 μg/L.The test results of 8 urinary iodine national standard materials with iodine concentration ranged from 64.5 to 883.0 μg/L were all within the given value range and the relative deviations were all below 3.0％ (n =12).No significant difference was found between the results of the 51 urine samples determined by the standard method (WS/T 107.1-2016) and the new method (t =0.836,P ＞ 0.05).Conclusions The new method to determine iodine in urine with no need for base urine match is successful established.This method has wide linear range,high sensitivity,good precision,accuracy and anti-interference ability,and is easy to be used and quickly to be analyzed of the test results,and is suitable for widely application in determining urinary iodine.