CN104215706A - Gas chromatography method for determining content of iodine in food - Google Patents
Gas chromatography method for determining content of iodine in food Download PDFInfo
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- CN104215706A CN104215706A CN201410422370.4A CN201410422370A CN104215706A CN 104215706 A CN104215706 A CN 104215706A CN 201410422370 A CN201410422370 A CN 201410422370A CN 104215706 A CN104215706 A CN 104215706A
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Abstract
The invention relates to an analysis method for determining content of iodine in food, and in particular relates to an analysis method for detecting the iodine by utilizing gas chromatography, belonging to the field of analysis chemistry. The gas chromatography method for determining the content of iodine in food is characterized in that a potassium carbonate-zinc sulfate ashing method is used for preprocessing a sample, and the gas chromatography is used for detecting the content of iodine. The gas chromatography method has beneficial effects that 1. the potassium carbonate-zinc sulfate ashing method is used for preprocessing the sample, so that the oxidization decomposition of organic matters can be promoted, organic iodine is converted into inorganic iodine, ashing is thorough, the volatile loss also can be reduced, and the detection recovery rate can be improved; 2. inorganic iodine and organic iodine in the food can be simultaneously determined, and the real content of iodine in the food can be accurately reflected; 3. the application range is wide, and the method is suitable for detecting the iodine in multiple food; 4. the detection limit of the iodine is 2.5ng.g<-1> and is obviously lower than the national standard; 5. the method is good in repeatability, and the labeling recovery rate can meet the analysis and determination requirement.
Description
Technical field
The present invention relates to a kind of analytical approach detecting content of iodine in food, particularly a kind of gas chromatography that adopts carries out the analytical approach detected, and belongs to analytical chemistry field.
Background technology
Iodine is the one trace element of needed by human, and about containing iodine 20-50mg in normal adult human body, wherein approximately 70%-80% mainly concentrates on thyroid gland.Iodine is the primary raw material of synthetic thyroid hormone, and its physiological function can be divided to the effect of energetic supersession, metabolism with to the effect of growing.In metabolism and energetic supersession, it not only stimulates the synthesis of nuclifort, protein, RNA (ribonucleic acid), but also take part in vitamin, water, sugar, fat and salt metabolism.The impact of growing is mainly manifested in and can promotes growing of the synthesis of protein and bone, and safeguard the normal configuration of central nervous system.Have these important physiological functions just because of iodine, often easily there is some thyroid disease or other pathology in human body under iodine deficiency state.As endemicgoiter, EndemicCretinism, newborn first subtract, in congenital malformation etc., even cause feeblemindedness.The iodine of human intake is about 80%-90% from food, but in food, the existence form of iodine and content are again have very large difference, and the intake therefore correctly assessing iodine in food is for elimination and control IDD (Iodine deficiency disorders) and seem particularly important.
The pre-treatment majority of current detection content of iodine directly adopts the reagent such as 2,6-xylenol, DMA to derive, and with Solvent Extract methods, the modes such as solid-phase microextraction carry out extracting, purifying.Such pre-treatment ignores the existence of organic iodine in food, the iodine of food can not be extracted completely.Another existing national standards GB5413.23-2010 adopts the content of gas chromatography determination iodine, its scope is but only applicable to infant food and dairy products, the determination of the content of iodine of numerous food has no bibliographical information, therefore can the sample-pretreating method of spectrophotometry etc. and the advantage of vapor-phase chromatography detecting device sensitivity, set up the new method of iodine in the mensuration food that the scope of application is wider, detection limit is lower, for the value and standard evaluating iodine further provides foundation.
Summary of the invention
The present invention is intended to the deficiency for existing analytical approach, a kind of Gas Chromatographic Method measuring content of iodine in food of specialized designs.This method is by improving sample-pretreating method, and simplify pre-treatment operation, save minute and cost, and antijamming capability is good, method precision is high, favorable reproducibility, accurately qualitative, and detection limit is starkly lower than national standard.
For achieving the above object, the present invention by the following technical solutions:
Measure a gas chromatography analysis method for content of iodine in food, adopt sal tartari-zinc sulfate ashing method carry out pre-treatment to sample and adopt gas chromatography to carry out content of iodine detection.
Concrete steps are as follows:
(1) sample ashing: take 0.2g ~ 0.5g sample and be placed in porcelain crucible, adds 1mL10% solution of potassium carbonate, 1mL10% solution of zinc sulfate infiltrates, and mixing is heated to non smoke and produces; Ashing in transposition muffle furnace, cooling;
(2) analyte derivative: dissolve ashing product with 10mL0.15mol/L aqueous sulfuric acid, then add 1mL butanone, 2mL3.5%H
2o
2, vortex mixes, and leaves standstill;
(3) sample extraction: add n-hexane extraction, merge organic phase, adding distil water is washed till neutrality, gets supernatant as need testing solution after leaving standstill;
(4) sample detection: adopt gas chromatograph, the content of iodine in need testing solution is measured.Preferred GC conditions is: chromatographic column: DB1701,30m × 0.32mm × 0.25 μm; Column temperature: 50 DEG C maintain 4min, rise to 130 DEG C, then rise to 230 DEG C with 50 DEG C/min with 15 DEG C/min; Injector temperature is 260 DEG C; Sample size 1 μ L; Split ratio is 3:1; Carrier gas is nitrogen, post flow: constant current 2.0mLmin
-1; Tail wind drift amount: 60mLmin
-1; Detecting device is electron capture detector, and detector temperature is 300 DEG C.
Further, a kind of gas chromatography analysis method measuring content of iodine in food, the detailed process of described step (3) divides 3 extractions for adding 20mL normal hexane, merge organic phase, with normal hexane constant volume to 25mL, adding distil water is washed till neutrality, gets supernatant as need testing solution after leaving standstill.
Method of the present invention overcomes the deficiency of prior art sample treatment, and compared with prior art, the present invention has following excellent results:
1, the inventive method adopts wet ashing to carry out pre-treatment to sample in sample pretreatment process, adds and help fogging agent (ZnSO before ashing
4) and fixing agent (K
2cO
3), can promote that oxidation operation decomposes on the one hand, the organic iodine in sample is converted into inorganic iodine, make sample ashing thorough; Can volatilization loss be reduced on the other hand, improve the recovery of detection.
2, the present invention adopts wet ashing method to carry out pre-treatment to sample, can inorganic iodine in Simultaneously test food and organic iodine, can reflect the real content of iodine in food more accurately, be conducive to formulating rational nutritious food scheme, realize balanced nutritious.
3, the inventive method measures the iodine in food, and its applied range, can be applicable to the detection of iodine in numerous food.
4, the detection limit of the inventive method is low: iodine standard solution is constantly diluted sample introduction, until the concentration when peak height of each material is noise 3 times is detection limit, now the concentration of iodine solution is 0.02ngmL
-1, be 0.2g in sample volume, in food, detecting of iodine is limited to 2.5ngg
-1, be starkly lower than the detection limit of iodine in GB.
5, the inventive method is reproducible, and recovery of standard addition meets the requirement analyzed and measure.
Accompanying drawing explanation
Fig. 1 is operational flowchart of the present invention;
Fig. 2 is the gas chromatogram of iodine standard items, laver sample and blank.
Specific implementation method
The present invention is further described by following specific embodiment, but does not limit the present invention.
Embodiment 1, measures content of iodine in 44 kinds of food.
1. instrument, reagent and instrument condition of work
(1) instrument
Agilent6890N gas chromatograph is furnished with electron capture detector (Agilent company of the U.S.); HY-1000 DEG C, high-temperature energy-conservation electric furnace (Heng Yu experimental electric furnace factory of Luoyang City); Victory spectrum experiment electric hot plate HT-300 (China Guangzhou Analysis &. Test Center); Ultrasonic washing instrument (Luxi, Shanghai Analytical Instrument Co., Ltd); Hydro-extractor TDZ5-WS (Hunan C1-esteraseremmer-N Xiang Yi Science and Technology Ltd.); Micro-whirlpool mixed instrument XW-80A (Luxi, Shanghai Analytical Instrument Co., Ltd); Sartorius electronic balance BSA224S (Guangzhou Shen Hua experimental instrument and equipment company limited).
(2) reagent
Potassium iodide (Chinese pharmaceutical biological product qualification institute, 99.5%); Butanone (analyzing pure, Tianjin red rock chemical reagent factory); It is pure that the concentrated sulphuric acid, normal hexane, sal tartari, zinc sulfate, hydrogen peroxide are analysis, buys in Guangzhou chemical reagent work.
(3) chromatographic condition
Chromatographic column: DB1701 (30m × 0.32mm × 0.25 μm); Column temperature: 50 DEG C maintain 4min, rise to 130 DEG C, then rise to 230 DEG C with 50 DEG C/min with 15 DEG C/min; Injector temperature is 260 DEG C; Sample size 1 μ L; Split ratio is 3:1; Carrier gas is nitrogen, post flow: constant current 2.0mLmin
-1; Tail wind drift amount: 60mLmin
-1; Electron capture detector temperature is 300 DEG C.
2. the preparation of standard working solution and the determination of standard working curve
(1) preparation of iodine standard solution
Precision takes pre-prior to potassium iodide 33.6mg dried in exsiccator, put in 100mL measuring bottle, adding distil water dissolves and is diluted to scale, shakes up rear accurately getting in 1mL to 250mL measuring bottle, and (potassium iodide concentration is 1.026 μ gmL as iodine standard solution to be diluted to scale
-1).
(2) determination of standard working curve
The accurate iodine standard solution drawing different volumes respectively, obtain the standard working solution of a series of iodine by sample-pretreating method process and carry out gas Chromatographic Determination, analyze result, with peak area A to concentration C drawing curve, iodine concentration is at 0.513 ~ 61.56ngmL
-1scope, concentration-peak area regression equation is A=60195C-29.941, R
2=0.9997, result shows that peak area and iodine concentration are good linear relation.
The relation of table 1 iodine standard solution peak area and concentration
3. the pre-treatment of sample
(1) sample ashing: take 0.2g ~ 0.5g sample (being accurate to 0.0001g) and be placed in porcelain crucible, adds 1mL10% solution of potassium carbonate, 1mL10% solution of zinc sulfate infiltrates, and mixing is heated to non smoke and produces; In transposition muffle furnace, 600 DEG C of ashing 90min, cooling.
(2) analyte derivative: dissolve ashing product with 10mL0.15mol/L aqueous sulfuric acid, then add 1mL butanone, 2mL3.5%H
2o
2, vortex mixing 1min, leaves standstill.
(3) sample extraction: add 20mL n-hexane extraction, point 3 extractions, merge organic phase, with normal hexane constant volume to 25mL, adding distil water is washed till neutrality, gets supernatant as need testing solution after leaving standstill.
(4) measure the peak area of need testing solution, the working curve obtained by step 2 calculates the content of iodine in sample.The testing result of sample, in table 2.
Determination of the content of iodine result in table 2 different food products
Embodiment 2, repeatability and recovery of standard addition test.
Get laver for 6 parts, sample, carry out pre-treatment and gas chromatographic analysis respectively, and calculate the recovery according to adding scalar sum measured value, in mensuration laver, the average content of iodine is 11.05 μ g/g, RSD is 1.74%, and result shows that the method repeatability is good.The recovery the results are shown in Table 3, and as shown in Table 3, in laver sample, the mark-on average recovery rate of iodine reaches 104.6%, RSD is 2.98%.The recovery of the method can meet the analysis requirement measuring content of iodine in food, is applicable to content of iodine analysis in food.
Table 3 recovery testu result
Claims (4)
1. measure a gas chromatography analysis method for content of iodine in food, it is characterized in that, adopt sal tartari-zinc sulfate ashing method carry out pre-treatment to sample and adopt gas chromatography to carry out content of iodine detection.
2. the gas chromatography analysis method measuring content of iodine in food as claimed in claim 1, it is characterized in that, concrete steps are:
(1) sample ashing: take 0.2g ~ 0.5g sample and be placed in porcelain crucible, adds 1mL10% solution of potassium carbonate, 1mL10% solution of zinc sulfate infiltrates, and mixing is heated to non smoke and produces; Ashing in transposition muffle furnace, cooling;
(2) analyte derivative: dissolve ashing product with 10mL0.15mol/L aqueous sulfuric acid, then add 1mL butanone, 2mL3.5%H
2o
2, vortex mixes, and leaves standstill;
(3) sample extraction: add n-hexane extraction, merge organic phase, adding distil water is washed till neutrality, gets supernatant as need testing solution after leaving standstill;
(4) sample detection: adopt gas chromatograph, the content of iodine in need testing solution is measured.
3. the gas chromatography analysis method measuring content of iodine in food as claimed in claim 2, it is characterized in that, the GC conditions that described step (4) adopts is: chromatographic column: DB1701,30m × 0.32mm × 0.25 μm; Column temperature: 50 DEG C maintain 4min, rise to 130 DEG C, then rise to 230 DEG C with 50 DEG C/min with 15 DEG C/min; Injector temperature is 260 DEG C; Sample size 1 μ L; Split ratio is 3:1; Carrier gas is nitrogen, post flow: constant current 2.0mLmin
-1; Tail wind drift amount: 60mLmin
-1; Detecting device is electron capture detector, and detector temperature is 300 DEG C.
4. the gas chromatography analysis method measuring content of iodine in food as claimed in claim 2, it is characterized in that, the detailed process of described step (3) divides 3 extractions for adding 20mL normal hexane, merge organic phase, with normal hexane constant volume to 25mL, adding distil water is washed till neutrality, gets supernatant as need testing solution after leaving standstill.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104458965A (en) * | 2014-12-19 | 2015-03-25 | 无锡华诺威动物保健品有限公司 | Detection method for content of iodine in feed |
| CN112461984A (en) * | 2020-11-19 | 2021-03-09 | 湖南新发展农牧科技有限公司 | Method for detecting iodine content in feed |
-
2014
- 2014-08-25 CN CN201410422370.4A patent/CN104215706B/en active Active
Non-Patent Citations (3)
| Title |
|---|
| 王敏荣等: "气相色谱法测定转基因食品油菜籽中的碘", 《中国卫生检验杂志》, vol. 21, no. 11, 30 November 2011 (2011-11-30), pages 2623 - 2624 * |
| 邓莲芬: "气相色谱-电子捕获检测器法(GC-ECD)测定食品中的碘化物", 《中国卫生检验杂志》, vol. 18, no. 8, 31 August 2008 (2008-08-31) * |
| 鄂颖等: "气相色谱法测定乳及乳制品中碘的影响因素", 《中国乳品工业》, vol. 40, no. 11, 31 December 2012 (2012-12-31) * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104458965A (en) * | 2014-12-19 | 2015-03-25 | 无锡华诺威动物保健品有限公司 | Detection method for content of iodine in feed |
| CN104458965B (en) * | 2014-12-19 | 2016-04-20 | 无锡华诺威动物保健品有限公司 | Content of iodine detection method in a kind of feed |
| CN112461984A (en) * | 2020-11-19 | 2021-03-09 | 湖南新发展农牧科技有限公司 | Method for detecting iodine content in feed |
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Address after: 510070 Guangzhou City, Guangzhou, Guangdong, No. 34 Patentee after: Institute of testing and analysis, Guangdong Academy of Sciences (Guangzhou analysis and testing center, China) Address before: 510070 Guangzhou City, Guangzhou, Guangdong, No. 34 Patentee before: GUANGDONG INSTITUTE OF ANALYSIS (CHINA NATIONAL ANALYTICAL CENTER, GUANGZHOU) |
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Address after: 510070 Guangzhou City, Guangzhou, Guangdong, No. 34 Patentee after: GUANGDONG INSTITUTE OF ANALYSIS (CHINA NATIONAL ANALYTICAL CENTER, GUANGZHOU) Address before: 510070 building 34, 100 Xianlie Middle Road, Guangzhou, Guangdong Patentee before: CHINA NATIONAL ANALYTICAL CENTER, GUANGZHOU |
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