CN103534587A - Method and apparatus for measuring cadmium in food - Google Patents
Method and apparatus for measuring cadmium in food Download PDFInfo
- Publication number
- CN103534587A CN103534587A CN201180069948.7A CN201180069948A CN103534587A CN 103534587 A CN103534587 A CN 103534587A CN 201180069948 A CN201180069948 A CN 201180069948A CN 103534587 A CN103534587 A CN 103534587A
- Authority
- CN
- China
- Prior art keywords
- cadmium
- food
- solution
- electrode
- concentration
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/12—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using combustion
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/416—Systems
- G01N27/48—Systems using polarography, i.e. measuring changes in current under a slowly-varying voltage
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/02—Food
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/416—Systems
- G01N27/42—Measuring deposition or liberation of materials from an electrolyte; Coulometry, i.e. measuring coulomb-equivalent of material in an electrolyte
Landscapes
- Health & Medical Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biochemistry (AREA)
- General Physics & Mathematics (AREA)
- Pathology (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Engineering & Computer Science (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Molecular Biology (AREA)
- Food Science & Technology (AREA)
- Combustion & Propulsion (AREA)
- Medicinal Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Abstract
The purpose is to measure the concentration of cadmium in a food with high accuracy in a simple manner. A food which is to be measured on the cadmium concentration is weighed precisely and pulverized. The pulverized sample is subjected to an ashing treatment by strong heating. The resultant sample is mixed with an acid and the mixed solution is shaken. A residue is removed from the mixed solution to produce a solution, and the solution is subjected to an electrochemical measurement. The method for the electrochemical measurement to be employed is an anodic stripping voltammetry or the like. The working electrode to be used in the electrochemical measurement is a copper electrode or the like. The temperature to be employed for the ashing treatment by strong heating is equal to or higher than the melting point of zinc and equal to or lower than the boiling point of cadmium, and the solution to be subjected to the measurement is adjusted to pH 3.5 to 5.5.
Description
Technical field
The present invention relates to measure by electrochemical gaging the method and apparatus of the concentration of the cadmium in food.
Background technology
Cadmium is extensively distributed in the nature that comprises soil, water and air, to such an extent as to the cadmium in environment source contains to a certain extent in most of food., in our country, there is extremely many cadmium pollution regions in the past, and started to relate to when itai-itai is next the EPDML research that cadmium exposes temporarily in mine.
Cadmium concentration in our country rice, compares with other country, tends to highlyer, and according to overall food investigation (2005), in Japan, from the absorption of the cadmium of rice, has almost occupied in addition half of food total amount, as shown in Figure 19.
According to food hygiene law, the cadmium content since in October, 1970 brown rice is defined as and is less than 1.0ppm (polished rice is defined as and is less than 0.9ppm) and therefore containing the sale of the brown rice of 1.0ppm or more cadmiums, is forbidden.Have and be not less than 0.4 and and bought and processed as emergency ration lower than the meter You government of the cadmium content of 1.0ppm.
In international body, the 29Jie Codex Alimentarius Commission holding in 2006 (CodexAlimentarius Commi s s ion) is final adopts this international standard value of cadmium of the 0.4mg/kg of rice and the 2.0mg/ of extra large Bivalvia (except oyster and scallop) and cephalopod (removing internal organ from it).Incidentally, the international standard value of cereal, wheat, vegetables etc. is used.
Consider such International Evaluation, requirement meets international standard by the acceptable standard value in comprising the food of brown rice so that MHLW at the 2005 Nian Xiang food security councils (Food Safe t y Comm i s s i on) the requests food relevant with " (Safe t y s ecur ement on t oday ' s cadm i um i nt ake f rom food) guaranteed in the security that the present situation absorbed from the cadmium of food is relevant " to healthy evaluation.As a result of, in June, 2008, the food security council concludes: the intake of acceptable cadmium was 7 μ g/kg (body weight)/weeks weekly.This be based on to Japanese population long-term by the food result of the EPDML research of the oral cadmium of rice under exposing for example.
Be used for for example official's analytical approach of the cadmium concentration of agricultural products of food, promulgated " limiting department's decree (Mi n i s t e ri a1ordinance defin i ng a me t hod of exam i n i ng a cadmi um amount r e1a t i ng t o r equ i r emen t s de s i gna t ed i n reg i on s a ga i ns t wh i ch fa rm1and g round pollution mea s ur e i s t aken) that the relevant cadmium amount of the requirement of appointment in the region to taking farmland land pollution countermeasure is carried out to method for measuring ".In this ministerial level decree, the method that detects the concentration of the cadmium in rice and brown rice is defined as to following methods: by heat, use nitric acid and sulfuric acid decompose sample and use afterwards solvent extraction in the method, then by atomic absorption spectrum, measure the content of the heavy metal in agricultural product.Figure 20 is the mensuration process flow diagram that official's analytical approach relates to.
In addition, as for measuring the universal method of the concentration of rice and the cadmium of brown rice, except atomic absorption photometer, also can carry out by inductively coupled plasma emission spectrometer (ICP), isotopic dilution mass spectrum (surface ionization method) and isotopic dilution mass spectrum (I CP-MS) mensuration of the cadmium in food.
Yet, " limit by taking the region of farmland land pollution countermeasure in the relevant cadmium amount of the requirement of appointment department's decree of carrying out method for measuring " in assay method complexity and spend a large amount of time like this of definition.Consider above situation, as the investigation of carrying out, propose to use the method (patent discloses 1) of x-ray fluorescence analysis device before the method, the simple method that the screening in contaminated by heavy metals agricultural product or farmland of take is object.
As other cadmium concentration assay method, the method (patent discloses 3 and 4) that also proposes to use the method (patent discloses 2) of electrochemical gaging and use the biology sensor that utilizes immune chromatograph.
Electrochemical gaging is wherein electromotive force, electric current and serve as location parameter and catch thus chemical substance with the method for testing of the variation of electrochemical reaction.
The characteristic of electrochemical gaging is its simplicity and convenience, and more specifically it allows high-sensitive mensuration thus for the chemical volume that is difficult to measure being converted into the electric weight that is easy to measure.And, for its device, be also extremely cheap.
Immunity spectrum is for by depending on that the color shown in cadmium concentration measures the method for cadmium concentration.In the method, food is by comminutor muller and being pulverized for example, and subsequently with the mixed in hydrochloric acid of about 0.1mo l/L.Afterwards, by centrifugal, filtration etc., remove the impurity from food as required, and therefore by water charging is concentrated by the aqueous solution obtaining by charging basket, then by concentrate with the antibody of cadmium reaction, mix.
List of references about prior art
Patent documentation
Patent discloses 1: Japanese Patent Application Publication No.2006-284378
Patent discloses 2: Japanese Patent Application Publication No.2005-49275
Patent discloses 3: Japanese Patent Application Publication No.2008-58207
Patent discloses 4: Japanese Patent Application Publication No.2004-323508
Summary of the invention
The technical problem to be solved in the present invention
As mentioned above, analytical equipment, the atomic absorption photometer for example using in official's analytical approach is expensive and its operation is so complicated to such an extent as to measure only can be by meticulous the carrying out of professional.Official's analytical approach is used various mineral acids and organic compound as shown in Figure 20, and the operation of therefore preparing sample is also complicated.And the health that has analysis project teacher is subject to the worry of the volatilization of sour gas, organic solvent etc. and the infringement of dispersion.
In addition, due to analytical equipment for example atomic absorption photometer, inductively coupled plasma emission spectrometer and isotopic dilution mass spectrum be huge fixing type, these are not suitable in the unusual object of many samples of food production and Food circulation field Fast Measurement.In addition, official's analytical approach need to approximately 5 days to obtain measurement result, during this period need to be at preservation food in storage box etc.Therefore production efficiency is bad.
Meanwhile, x-ray fluorescence analysis has following problem: do not allow the mensuration of solution, to such an extent as to can not relate to the test of cadmium of the stripping quantity of cadmium; Need to carry out calculating concentration ratio by quality measurement before carbonization and afterwards; Unless its sensitivity is so low to such an extent as to concentrate, otherwise can not measure; The use of X-ray is dangerous; Deng.
The type of the electrode using in electrochemical gaging is working electrode, contrast electrode and to electrode.In common situation, electromotive force is because the pollution of the working electrode that the carrying out along with electrochemical reaction produces changes.Therefore,, in the situation of the heavy metal ion in measuring aqueous solution, adopt the electromotive force regulating with respect to the working electrode of contrast electrode for being necessarily determined at subsequently working electrode and the method to the variation of electric current mobile between electrode.
In most of generalized cases, use mercury as electrode; Yet mercury stripping is in sample solution, even with trace, it also causes the problem of discarded sample solution.
And, use the method for the biology sensor that utilizes immune spectrum to require for concentrated pre-service and the generation of cadmium is subject to for example problem of the impact of zinc, manganese and copper of some metals.
In addition, although immune spectrographic technique requires to produce with the complex compound of protein to make immune animal can form antibody, because element cadmium has little molecular weight, produce operation with the complex compound of protein so complicated to such an extent as to only can realize by professional.And, the generation cost of antibody two months or more days.Therefore and be not suitable for the In situ Screening as one of simple object of measuring because the antibody producing is commercially available acquisition, but very expensive, comprise that the mensuration of very many mensuration targets requires large cost, and.
Consider above situation, object of the present invention be provided for measuring cadmium concentration method and for measuring the device of the concentration of cadmium, wherein the concentration of the cadmium in food can with simple mode high precision measured.
For the mode of dealing with problems
Can realize above-mentioned target according to of the present invention for measuring the method for cadmium, be for measuring the method for the cadmium of food, and it is characterized in that: the ashing food by heat-flash; The food that makes the ashing by heat-flash mixes with acid and afterwards from the solution separation solution of mixing; With make solution carry out electrochemical gaging.
Electrochemical gaging adopts according to the assay method of the anodic stripping voltammetry without mercury, wherein uses copper electrode to replace mercury electrode.
And what can realize above-mentioned target is for measuring the device of the cadmium of food for measuring the device of cadmium, and it is characterized in that having: the heat-flash ashing device of ashing food for passing through heat-flash; The device that ashed food and acid mix for passing through heat-flash ashing device and afterwards the separated solution of the solution from mixing is stored; For serving as the copper electrode of working electrode and the device that electrode is flooded at solution; For apply the device of the voltage that the cadmium that makes to contain at solution separates out on working electrode at working electrode with between to electrode; For apply the device of the voltage that makes the cadmium stripping of separating out on working electrode at working electrode with between to electrode; And for detection of working electrode and the device to electric current mobile between electrode.
Accompanying drawing explanation
[Fig. 1] be illustrate according to one embodiment of the invention for measuring the process flow diagram of the method for cadmium.
[Fig. 2] is by standard adding method with by according to the electromotive force-current characteristic curve obtaining for measuring the method for cadmium of embodiment of the present invention.
[Fig. 3] is the absolute calibration curve of the electromotive force-current characteristics curve based on by obtaining according to the method for the mensuration cadmium of embodiment of the present invention.
[Fig. 4] be by standard adding method and by according to embodiment of the present invention for measuring electromotive force-current characteristics curve of the cadmium standard solution that the method for cadmium obtains, wherein (a) relates to the cadmium standard solution of 0.01mg/L, (b) relate to the cadmium standard solution of 0.03mg/L, and the cadmium standard solution that (c) relates to 0.05mg/L.
[Fig. 5] is the concentration of cadmium standard solution and the contrast between measured value.
[Fig. 6] is the contrast between official's analytical approach and the measured value of simplifying the brown rice standard model between analytical approach (its for according to assay method of the present invention, inductively coupled plasma emission spectrometer (I CP) carries out by using, the method omitted the assay method of heat-flash ashing processing).
[Fig. 7] is by electromotive force-current characteristics curve of standard adding method and the brown rice standard model that obtains by short-cut method (its for according to assay method of the present invention, omitted heat-flash ashing process by the method).
[Fig. 8] is the impact on the cadmium concentration value of measuring of the temperature processed for heat-flash ashing.
[Fig. 9] is time of processing for heat-flash ashing impact on the cadmium concentration value of measuring.
The impact of the pH value of the solution that [Figure 10] obtains while being electrochemical gaging on the cadmium concentration value of measuring.
[Figure 11] is the contrast between the guaranteed performance of brown rice standard model and the cadmium concentration value of mensuration.
[Figure 12] is for studying the mensuration process flow diagram of organic substance on the impact of the cadmium concentration value of measuring.
[Figure 13] be by standard add obtain to it, added electromotive force-current characteristics curve of the cadmium standard solution of starch.
[Figure 14] is the measurement result of the cadmium content in clam meat, and wherein (a) is electromotive force-current characteristics curve and (b) is the Absolute Calibration curve based on (a).
[Figure 15] is the measurement result of the cadmium content in scallop, and wherein (a) is electromotive force-current characteristics curve and (b) is the Absolute Calibration curve based on (a).
[Figure 16] is the measurement result of the cadmium content in English walnut, and wherein (a) is electromotive force-current characteristics curve and (b) is the Absolute Calibration curve based on (a).
[Figure 17] is the measurement result of the cadmium content in cashew nut, and wherein (a) is electromotive force-current characteristics curve and (b) is the Absolute Calibration curve based on (a).
[Figure 18] is the measurement result of the cadmium content in Queensland nut, and wherein (a) is electromotive force-current characteristics curve and (b) is the Absolute Calibration curve based on (a).
[Figure 19] is the curve that the cadmium absorption ratio of each japanese food is shown.
[Figure 20] measures flow process according to the cadmium of official's analytical approach.
Embodiment
The present invention relates to have the method for the cadmium concentration in the mensuration food of high precision and rapidity and for measuring the device of the concentration of cadmium, and it is characterized in that: make the food of the concentration of cadmium to be determined carry out heat-flash ashing processing; Then the food that has carried out heat-flash ashing processing is dissolved in acid; And make afterwards solution carry out electrochemical gaging.
Therefore in food, for example, in brown rice, impurity such as iron, calcium, magnesium, zinc, cadmium etc. are combined with phytic acid, and with the form enrichment of phytate, exist.
Phytic acid is a kind of active material and has C
6h
18o
24p
6composition formula and 660.08 molecular weight.It is particularly main phosphorus storage form in seed at many plant tissues, and has extremely strong chelating effect to such an extent as to be combined with many kinds of metal ions securely.
Therefore, in food, above-mentioned impurity is combined with phytic acid, and the form with phytate exists thus, to such an extent as in the situation by electrochemical method determining cadmium (target that will measure in the present invention), needs to decompose phytate and independent cadmium separation (its hypothesis exists with the form of phytate).
Phytic acid is organic substance and is therefore easy to decompose by heating.Yet residual impurity is the state mutually combining, to such an extent as to can not cadmium separation.Therefore the combination in impurity need to be disconnected with cadmium separation.
Therefore, when heat-flash ashing is processed, minimum heating-up temperature need to be defined as to the fusing point (419.6 ℃, the maximum temperature that it is decomposed and may be combined with cadmium in rear impurity for phytate) that is not less than zinc, before cadmium is combined with zinc, melting occur thus separated.Meanwhile, maximum heating temperature is adjusted into the boiling point (756.0 ℃) of cadmium or lower, stops thus the cadmium loss causing due to evaporation.
In the present invention, the food that carries out cadmium concentration mensuration has no particular limits.For example, in the research that International Health Institute of Science and local healthy institute cooperation carry out, food is extensively categorized as " rice and rice product ", " cereal and potato ", " beans of beans and processing ", " bright-coloured vegetables ", " vegetables and sea grass ", " marine product " and " other ", and the present invention relates to the food of all such classification.
According to the present invention, measure the method for cadmium concentration, only from shortening minute, consider, verified: at the minute of approximately 5 days by conventional cost in using official's analytical approach of expensive large-scale fixedly analytical equipment, for example inductively coupled plasma emission spectrum, can to shorten to approximately 2 hours.
The risk of putting on market in order to eliminate contaminated agricultural product, the object of the invention is to provide simple assay method, wherein by employing, allows the electrochemical gaging of high-precision measuring to make on-site measurement become feasible.Therefore, they are eager to adopting electrochemical assay method to study, and the concentration that reaches thus the cadmium in food can obtain fast by mensuration flow process as shown in table 1 the discovery of measuring.
Electrochemical gaging is the very simple method of measuring the variation of electric current and voltage, and these variations are caused by the oxidation-reduction reaction on electrode; However, it has advantages of the high-sensitive mensuration of permission and produces and consume partly hardly.
And the coulomb analysis of quoting in embodiments of the invention is the technology of repeatability excellence, wherein detects the total amount of the target components in sample.Therefore, can be by coulomb analysis for expecting the general object to the home and overseas of enhancement of environment and good society economic circulation major contribution.
According to electrochemical determining device of the present invention, by the heat-flash ashing device for the ashing sample by heat-flash, the unit (for the device of storage solutions) of introducing wherein sample, working electrode, contrast electrode, to electrode, for control working electrode electromotive force device and for measuring working electrode and the device of electric current mobile between electrode being formed.
Only requirement can at air, (or in oxygen stream, heated sample and its be exemplified as electric furnace etc. to heat-flash ashing device.
As for controlling the device of the electromotive force of working electrode, known device is available.When the device of controlling electromotive force exists, even at working electrode, along with the progress of electrochemical reaction, become and pollute to such an extent as to electromotive force is changed, can keep consistently the electromotive force of working electrode (with respect to contrast electrode) constant.Therefore, at working electrode and between to electrode mobile electric current therein the electromotive force of working electrode keep measuring under constant state.
In thering is the electrochemical determining device of above-mentioned structure, preferably by working electrode, contrast electrode, to electrode, for unit and the electrolyte solution optimization of working sample.
As working electrode, can use platinum electrode, gold electrode and carbon electrode and copper electrode.
As contrast electrode, can consider type, stability and ease and for example, from known contrast electrode (standard hydrogen electrode), select suitable electrode.The present invention adopts silver-silver chloride electrode as the example of contrast electrode.
To electrode preferably in optimization aspect type and size (surface area).As to electrode, in most applications, use platinum electrode, but electrode is not limited to platinum electrode.
In addition, electrolyte solution preferably the oxygen of type, dissolving remove and concentration aspect optimization.For example, determine certain volume sample water and with the reagent mix of the specific purpose being formed by electrolyte and buffer solution, provide thus it as test(ing) liquid to be determined.Preferably select to have the unit of the size and dimension of applicable mensuration.
The method for electrochemical gaging of carrying out in electrochemical determining device of the present invention, can illustration anodic stripping voltammetry.Anodic stripping voltammetry is concentrated and determine the method for the concentration of concentrated thus heavy metal substance by the current value obtaining when oxidation and the stripping heavy metal substance by the heavy metal ion reduction containing in aqueous solution so that by them on electrode, and is the method for high assay sensitivity.
With reference now to Fig. 1, will discuss according to of the present invention for measuring the method for cadmium concentration.
First, carry out wherein will measuring the food weighing of cadmium concentration (following, food to be referred to as to " sample ") and the step S1 pulverizing.For the device of pulverizing, can suitably select per sample, and therefore it can be coffee grinder etc. in the situation of ground cereal and seed, or can be cutter etc. in the situation of pulverizing clam meat, scallop etc.
In step S2, the amount that the sample weighing of pulverizing is required to have the mensuration of cadmium concentration.If the form that the sample of pulverizing is particle, it can sieve.The sieve size of sieve can be suitable select.
In step S3, the sample of the pulverizing having weighed is carried out to heat-flash ashing processing in step S2.
In the present invention, to process be for example, by sample being placed in air or oxygen stream and being baked the regular hour at the temperature of approximately 600 ℃ and decompose thus or remove moisture, organic substance (carbohydrates, protein, lipid and vitamin) and have the processing that for example chlorine carries out of lower boiling dead matter in electric furnace in heat-flash ashing.
By carrying out heat-flash processing, not only organic substance can be from sample ashing and removing, and allow be not less than the boiling point of zinc and at the temperature higher than the boiling point of cadmium, do not heating.Thus, the combination of tending to suppress form between the impurity of mensuration of cadmium is disconnected with separated.
In step S4, the sample that allows to carry out heat-flash ashing processing in step S3 is cooling, afterwards it is mixed with sour.To have no particular limits with the sour type of sample mix, so that can use not and acid such as the hydrochloric acid of electrode reaction for measuring, dilute sulfuric acid etc.
In step S5, the solution of the mixing obtaining by step S4 is vibrated, and in step S6, filter afterwards.Type for the filtrator that filters only requires as removing from the solution mixing the filtrator of residue, and therefore it can carry out suitable selection (for example filter paper).
In step S7, the filtrate obtaining by S6 is carried out electrochemical gaging.
Electrochemical gaging preferably carries out according to standard adding method.For example, by the standard solution of independent service test liquid and two kinds of different interpolation levels, measure to draw three electromotive force-current characteristics curves, and the peak area of calculated curve to be to provide the concentration dependent calibration curve of interpolation with standard solution afterwards, the concentration in thus can determination test liquid.Peak area is according to the concentration of material to be determined, material to be determined and different for the material of electrode; In the present invention, more specifically, from-0.62V to the point of the minimum current value-0.58V to the strokes and dots straight line to the minimum current value-0.5V at-0.5V, and calculate the area being surrounded by straight line and electromotive force-current characteristics curve.
Below, with reference to specific embodiment, discuss in detail according to of the present invention for measuring the method for the concentration of cadmium.Yet, according to of the present invention for measure cadmium concentration method and for measuring the device of the concentration of cadmium, be not limited to these embodiment.
[embodiment 1]
From independent administrative corporation's National Institute for Environmental Studies (National Institute for Environmental Studies), obtain the standard brown rice sample of the three types of the concentration all with known cadmium.The concentration of their cadmium is respectively 0.023mg/kg, 0.32mg/kg and 1.82mg/kg.
Standard brown rice powdered sample is the environmental standard sample of preparing while measuring trace element amount in rice, and its object is for by carrying out the degree of accuracy of evaluating and measuring value and determination and analysis method with this sample.This standard model is by the sample composition of the three types of a series of cadmium concentrations different (low Cd level, medium Cd level and high Cd level).Brown rice powder standard sample is the reference value of standard model and its guarantee value that be defined as 13 kind elements and 9 kind elements relevant with constituent content.
In embodiment 1, the concentration of the cadmium in brown rice is measured according to the assay method the present invention relates to.With reference to figure 1 by detailed discussion embodiment 1.
By independent administrative corporation's National Institute for Environmental Studies, obtain standard brown rice sample.This standard brown rice sample is the powdered samples of having carried out the step S1 as shown in the mensuration process flow diagram of Fig. 1.To this sample weighing to there is the amount (step S2) of 1g.
Then, the brown rice of the pulverizing weighing is injected to evaporating dish or crucible in step S2, and (step S3) processed in the heat-flash ashing of carrying out afterwards in electric furnace.
And, the evaporating dish or the crucible that carry out heat-flash ashing processing are transferred in exsiccator and allowed cooling.Then, inclusions is injected to the glass container with the 50mL of lid, add wherein afterwards the hydrochloric acid (step S4) of the 1mo1/L of 20mL.
By oscillator with the rotational speed of 150r pm by 1 hour (step S5) of glass container vibration, use afterwards filter paper No.5C to filter (step S6).The filtrate of required amount is injected to the volumetric flask of 50mL, and to it, acidic liquid chemicals of 2.5mL and the reagent solution of 2.5mL are sequentially added with this, with distilled water, be diluted to 50mL afterwards.
The electrochemical determining device " F I ELDER " (HOE-100 type) that the solution of dilution is obtained by HOKUTO DENKO CORPORATION by use carries out the mensuration (step S7) of current value.
The embodiment of the preparation of the acidic liquid chemicals that uses in step S7 and reagent solution is below discussed.
<for the preparation of the method for acidic liquid chemicals>
By 120mL concentrated hydrochloric acid being diluted with distilled water, be that 1L prepares acidic liquid chemicals.
<for the preparation of the method for reagent solution>
By following material being injected to the volumetric flask of 1L and being that 1L prepares reagent solution with distilled water by its dilution.
Potassium chloride (223.65g)
NaOH (57.14g)
Acetic acid (8.6mL)
Sodium acetate (28.7g)
The electrochemical determining device using: copper electrode is as working electrode, platinum electrode is as to electrode, and silver-silver chloride electrode is as contrast electrode.
Measurement result is shown in Fig. 2 and 3.Fig. 2 illustrates electromotive force-current characteristics curve, and Fig. 3 illustrates the absolute calibration curve obtaining according to standard adding method.In electromotive force-current characteristics curve as shown in Figure 2, the Shi Ge peak, peak at-0.53V place.In addition, Fig. 2 has shown three kinds of electromotive force-current characteristics curves (0mg/L, 0.02mg/L and 0.04mg/L), and more particularly, illustrate sample solution electromotive force-current characteristics curve (Fig. 4,7 and 13-18 be also identical situation), described electromotive force-current characteristics curve is to be set to obtain for the solution of the standard of standard adding method by adding 100 μ m.
Fig. 4 illustrates by measuring each the electromotive force-current characteristics curve obtaining in three kinds of cadmium standard solution (0.01mg/L, 0.03mg/L and 0.05mg/L), and confirming increases along with the increase of the concentration of cadmium at the peak of the cadmium at-0.53V place.
Fig. 5 shown the concentration of cadmium standard solution and the value measured by F I ELDER between relation.R
2value be 0.9933, and the slope of the tropic is 0.9783 to such an extent as to approaches 1, this means that it can accurately measure by electrochemical gaging the concentration of cadmium.
Fig. 6 has shown that according to the assay method wherein showing in Fig. 1, omitting heat-flash ashing processes the assay method of (step S3), uses inductively coupled plasma emission spectrum (ICP) to measure the result of three kinds of brown rice standard models that obtained by independent administrative corporation's National Institute for Environmental Studies.
R
2value be 0.9978, and the slope of the tropic is 0.9675 to such an extent as to approaches 1, by its confirmation: only from shortening minute, consider, can be by by using the conventional cost minute of about 5 days in official's analytical approach of expensive large-scale fixedly analytical equipment to shorten to about 2 hours.
Yet, mensuration flow process shown in Fig. 1 and that omit heat-flash ashing processing by it does not allow to measure according to electrochemical gaging the concentration of the cadmium in brown rice, this be because: as obviously seen by Fig. 7, at-0.53V (peak of detectable cadmium), locate not confirm the difference at peak, and therefore can not get the normal electromotive force-current characteristics curve based on standard adding method and therefore can not get absolute calibration curve, and therefore can not determine the concentration of cadmium.
The brown rice standard model of the three types obtaining from independent administrative corporation's National Institute for Environmental Studies is respectively the sample (sample (L) with low cadmium content, wherein the concentration of cadmium is 0.023mg/kg), there is the sample (sample (M) of medium cadmium content, wherein the concentration of cadmium be 0.32mg/ this) and there is the sample (sample (H), wherein the concentration of cadmium is 1.82mg/kg) of high cadmium content.
The brown rice standard model of three types contains zinc, chlorine, potassium, bromine, mercury, selenium, sodium, rubidium etc. as impurity, and thinks that any one or combination arbitrarily of these impurity suppress the mensuration of cadmium concentration.The content of the every kind of element containing in brown rice standard model, fusing point and boiling point are shown in table 1.
[table 1]
The cadmium containing in brown rice standard model and the fusing point of representational impurity and boiling point
The boiling point of cadmium is 765 ℃.Therefore, when being heated to 765 ℃ or when higher, cadmium evaporation and being dispersed in air.Therefore think: if sample is heated to and is not less than the fusing point of zinc and not higher than the temperature of the boiling point of cadmium, the combination between impurity can be disconnected with separated they.
(1) impact of heat-flash ashing temperature on the mensuration of cadmium concentration
With the brown rice standard model with the cadmium concentration of 1.82mg/kg, measure the concentration of cadmium, under this condition, the heat-flash ashing time is that 60 minutes and heat-flash ashing temperature change between 0,120,200,400,450,500,550,600,650,700,750,800 and 1000 ℃.Its measurement result is shown in Fig. 8.
From Fig. 8, it is evident that: be not less than the fusing point of zinc and higher than the heat-flash ashing temperature of the boiling point of cadmium, do not allow the Accurate Measurement of cadmium concentration.And by the heat-flash ashing temperature of 530 to 630 ℃ is provided, the concentration of accurately measuring cadmium becomes possibility.Although measure identical sample by analytical equipment I CP, its result is not so that support according to the result of cadmium assay method of the present invention yet.
(2) impact of heat-flash ashing time on the mensuration of cadmium concentration
By the concentration that has this brown rice standard model of cadmium concentration of 1.82mg/ and measure cadmium, under this condition, heat-flash ashing temperature is to change between 0,10,20,30,40,50,60,90,120,150 and 180 minute 600 ℃ and heat-flash ashing time.Its measurement result is shown in Fig. 9.
From Fig. 9, it is evident that: when the heat-flash ashing time is in the scope of 45 to 90 minutes, almost 100% cadmium is all extracted out from brown rice.
(3) impact of the pH value of test(ing) liquid on the mensuration of cadmium concentration
In electrochemical gaging, the pH value of test(ing) liquid is to measuring precision performance tremendous influence.Therefore, test pH is on relating to the impact of test of the stripping quantity of cadmium.Method of testing will be in following discussion.
First, the cadmium solution of preparation 2.5mg/L is as standard model.
In preparing the method for 2.5mg/L cadmium solution, with the hydrochloric acid of 1mo l/L, by the concentrated hydrochloric acid dilution of the cadmium standard solution of the 1000mg/L of 0.25mL and 0.6mL, be 100mL.
By the distilled water of about 25mL being injected into the volumetric flask of 50mL and adding wherein afterwards the cadmium solution of the 2.5mg/L of 600 μ L to obtain test(ing) liquid.The test(ing) liquid of preparing requested number.
In order to regulate pH, in volumetric flask respectively the amount with 0 μ L, 50 μ L, 100 μ L, 200 μ L, 300 μ L, 400 μ L, 500 μ L and 600 μ L add 2N NaOH.Wherein 2.5mL acidic liquid chemicals and 2.5mL reagent solution are sequentially added with this afterwards, then with distilled water diluting, arrive 50mL.
And to the 2N NaOH that adds 50 μ L in each of other volumetric flask, then the amount with 20 μ L, 50 μ L, 100 μ L and 200 μ L adds 4N hydrochloric acid, prepares thus low pH solution.
Each test(ing) liquid is injected to the unit only using at FIELDER and measures electric current, calculate thus the concentration of cadmium.The measurement result of the concentration of cadmium is shown in Figure 10.
To the test(ing) liquid with 50mL amount of preparation, add the cadmium solution of the 2.5mg/L of 600 μ L, so that their cadmium concentration is 0.03mg/L.By the measurement result shown in Figure 10, can be confirmed: when pH value is not higher than 3.5 and while being not less than 5.5, cadmium concentration is beyond real value.This has verified and by relating to electrochemical determination method of the present invention, has measured in the situation of cadmium concentration, and cadmium concentration can be by pH is adjusted in 3.5 to 5.5 scope and mensuration accurately.Also further confirm: by pH is adjusted in 4.0 to 5.0 scope, can measure more accurately the concentration of cadmium.
(4) according to the mensuration of the concentration of cadmium in the standard brown rice sample of electrochemical determination
The Figure 11 that the results are shown in of three kinds of standard brown rice samples obtaining from independent administrative corporation's National Institute for Environmental Studies will be measured according to electrochemical gaging.
R
2value be 0.9999, and the slope of the tropic is 1.0459 to such an extent as to approaches 1, this means with the degree of accuracy of enough degree and measures.
(5) according to electrochemical gaging, measure the degree of accuracy of cadmium concentration
According to the mensuration flow process of Fig. 1, according to electrochemical gaging, the standard brown rice sample with 1.82mg/kg cadmium concentration obtaining from independent administrative corporation's National Institute for Environmental Studies is repeated to measure.
Measure and carry out under the following conditions: the amount with 1g weighs brown rice standard model; The hydrochloric acid that adds the 1mo1/L of 20mL; Filtrate is the amount of 4mL; Heat-flash ashing temperature is 600 ℃; And the heat-flash ashing time is 1 hour.By the table 2 that the results are shown in of the concentration of mensuration cadmium.As shown in table 2, Z-factor (CV) is 4.7%, and this has verified the mensuration of carrying out the concentration of cadmium with high degree of accuracy.
[table 2]
According to electrochemical gaging, carry out the result of replicate analysis brown rice standard model
CV=4.7％
(6) impact of organic substance on the mensuration of cadmium concentration
In order to test the impact of organic substance on the mensuration of cadmium concentration, according to the preparation of mensuration process flow diagram and starch-mixed cadmium standard solution shown in Figure 12, carry out thus the mensuration of cadmium concentration.The mensuration of cadmium concentration the results are shown in Figure 13.
In the situation of using copper electrode as working electrode, the peak voltage of cadmium is-0.53V.As shown in Figure 13, the peak under this voltage is measured apparently.
Therefore, if starch is mixed in solution to be determined, do not suppress the peak of cadmium, to such an extent as to can say only add organic substance for example starch do not affect the mensuration of cadmium concentration.
(7) cadmium concentration of every kind of food is measured
The application of the invention for measuring the Figure 14 to 18 that the results are shown in that the device of cadmium concentration measures the concentration of the cadmium of every kind of food.
Select clam meat, scallop, English walnut, cashew nut and Queensland nut as measuring target, and measure each the cadmium concentration in these food according to the mensuration flow process of Fig. 1.Incidentally, according to every kind of food, differently use breaking method (step S1).More specifically, by clam meat from shell separated and on the chopping board that cuts meat with cutter by its meticulous mincing, and the scallop having boiled directly on the chopping board that cuts meat with meticulous the mincing of cutter.Meanwhile, English walnut, cashew nut and Queensland nut are selected from the mixing nut of commercially available acquisition, then by coffee grinder, pulverize independently for approximately 10 seconds.Measure every kind of food cadmium concentration the results are shown in table 3.Although also measure identical sample by I CP, its result to such an extent as to support according to the result of cadmium assay method of the present invention.
[table 3]
Measurement result
As verified in table 3, according to of the present invention, for measuring the method for cadmium concentration, allow dissimilar food to carry out cadmium concentration mensuration.
As mentioned above, according to of the present invention for measure cadmium concentration method and for measure that the device of cadmium concentration allows simply and easily the cadmium of food mensuration and do not need so that require the complicated operation of professional knowledge and technical ability and do not need eight kinds or more kinds of reagent.
And, likely within the short time (approximately 3 hours), accurately measure the concentration of the cadmium in food.
The present invention does not use expensive large fixedly analytical equipment, and by adopting wherein the electrochemical gaging of acquisition height Accurate Measurement at short notice to make on-site measurement feasible.Therefore the present invention can be for the various uses that to take by the elimination of the agricultural product of the cadmium pollution risk that for example brown rice comes into the market be representative.
Claims (7)
1. measure a method for the cadmium in food, should be characterised in that for measuring the method for cadmium:
The ashing food by heat-flash;
To mix with acid by the food of heat-flash and ashing and afterwards from the solution separation solution of mixing; With
Make this solution carry out electrochemical gaging.
2. the method for mensuration cadmium according to claim 1, is characterized in that, electrochemical gaging is anodic stripping voltammetry.
3. according to the method for claim 1 or mensuration cadmium claimed in claim 2, it is characterized in that, the working electrode using in electrochemical gaging is copper electrode.
4. according to the method for claim 1 or mensuration cadmium claimed in claim 2, it is characterized in that, the time spending for the ashing by heat-flash is 45 to 90 minutes.
5. according to the method for claim 1 or mensuration cadmium claimed in claim 2, it is characterized in that, for the temperature of the ashing by heat-flash, be not less than the fusing point of zinc and not higher than the boiling point of cadmium.
6. according to the method for claim 1 or mensuration cadmium claimed in claim 2, it is characterized in that, this solution is prepared as to the pH with 3.5 to 5.5.
7. for measuring a device for the cadmium of food, should be characterised in that to have for measuring the device of cadmium:
The heat-flash ashing device of ashing food for passing through heat-flash;
The device that ashed food and acid mix for passing through heat-flash ashing device and afterwards the separated solution of the solution from mixing is stored;
For serving as the copper electrode of working electrode and the device that electrode is flooded at solution;
For apply the device of the voltage that the cadmium that makes to contain at solution separates out on working electrode at working electrode with between to electrode;
For apply the device of the voltage that makes the cadmium stripping of separating out on working electrode at working electrode with between to electrode; With
Device for detection of mobile electric current at working electrode and between to electrode.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP2011/058682 WO2012137314A1 (en) | 2011-04-06 | 2011-04-06 | Method and apparatus for measuring cadmium in food |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103534587A true CN103534587A (en) | 2014-01-22 |
| CN103534587B CN103534587B (en) | 2015-11-25 |
Family
ID=46968752
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201180069948.7A Expired - Fee Related CN103534587B (en) | 2011-04-06 | 2011-04-06 | For measuring the method and apparatus of the cadmium in food |
Country Status (3)
| Country | Link |
|---|---|
| KR (1) | KR20130133029A (en) |
| CN (1) | CN103534587B (en) |
| WO (1) | WO2012137314A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10073019B2 (en) | 2014-11-06 | 2018-09-11 | Cem Corporation | Rapid quantitative element testing |
| CN111307549A (en) * | 2020-03-18 | 2020-06-19 | 国家粮食和物资储备局科学研究院 | Method for rapidly extracting multiple elements from grains |
| CN112098482A (en) * | 2020-09-09 | 2020-12-18 | 南京腾森分析仪器有限公司 | Method for detecting lead in food |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5759442B2 (en) * | 2012-12-28 | 2015-08-05 | 株式会社堀場製作所 | Electrochemical analysis method, electrochemical analyzer and reagent set |
| CN103645201A (en) * | 2013-12-13 | 2014-03-19 | 彭新凯 | Method for rapidly detecting heavy metal cadmium in rice based on X-ray fluorescence |
| EP3100040A4 (en) * | 2014-01-29 | 2017-09-20 | Lantmännen ek för | Electrochemical methods and system for detecting cadmium |
| KR20200069723A (en) | 2018-12-07 | 2020-06-17 | 엘지전자 주식회사 | control method of refrigerator |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005049275A (en) * | 2003-07-30 | 2005-02-24 | Japan Science & Technology Agency | Method of detecting cadmium in foods, and apparatus for the same |
| JP2006284378A (en) * | 2005-03-31 | 2006-10-19 | National Institute Of Advanced Industrial & Technology | Simplified analysis method of heavy metal in agricultural product |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5319485B2 (en) * | 2009-10-16 | 2013-10-16 | 北斗電工株式会社 | Method and apparatus for measuring cadmium in food |
-
2011
- 2011-04-06 WO PCT/JP2011/058682 patent/WO2012137314A1/en active Application Filing
- 2011-04-06 KR KR1020137026201A patent/KR20130133029A/en not_active Application Discontinuation
- 2011-04-06 CN CN201180069948.7A patent/CN103534587B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005049275A (en) * | 2003-07-30 | 2005-02-24 | Japan Science & Technology Agency | Method of detecting cadmium in foods, and apparatus for the same |
| JP2006284378A (en) * | 2005-03-31 | 2006-10-19 | National Institute Of Advanced Industrial & Technology | Simplified analysis method of heavy metal in agricultural product |
Non-Patent Citations (1)
| Title |
|---|
| 坂山邦彦: "電気化学分析法による農作物中のカドミウム分析法の研究", 《滋賀県工業技術総合センター2009研究報告》, 31 August 2010 (2010-08-31), pages 60 - 62 * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10073019B2 (en) | 2014-11-06 | 2018-09-11 | Cem Corporation | Rapid quantitative element testing |
| CN111307549A (en) * | 2020-03-18 | 2020-06-19 | 国家粮食和物资储备局科学研究院 | Method for rapidly extracting multiple elements from grains |
| CN111307549B (en) * | 2020-03-18 | 2023-03-14 | 国家粮食和物资储备局科学研究院 | Method for rapidly extracting multiple elements from grains |
| CN112098482A (en) * | 2020-09-09 | 2020-12-18 | 南京腾森分析仪器有限公司 | Method for detecting lead in food |
| CN112098482B (en) * | 2020-09-09 | 2023-01-10 | 南京腾森分析仪器有限公司 | Method for detecting lead in food |
Also Published As
| Publication number | Publication date |
|---|---|
| CN103534587B (en) | 2015-11-25 |
| WO2012137314A1 (en) | 2012-10-11 |
| KR20130133029A (en) | 2013-12-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103534587B (en) | For measuring the method and apparatus of the cadmium in food | |
| Andrade Korn et al. | Sample preparation for the determination of metals in food samples using spectroanalytical methods—a review | |
| Ferreira et al. | Slurry sampling—an analytical strategy for the determination of metals and metalloids by spectroanalytical techniques | |
| Zounr et al. | A highly selective and sensitive ultrasonic assisted dispersive liquid phase microextraction based on deep eutectic solvent for determination of cadmium in food and water samples prior to electrothermal atomic absorption spectrometry | |
| Sorouraddin et al. | Development of a dispersive liquid-liquid microextraction method based on a ternary deep eutectic solvent as chelating agent and extraction solvent for preconcentration of heavy metals from milk samples | |
| Oeser et al. | High‐precision Fe and Mg isotope ratios of silicate reference glasses determined in situ by femtosecond LA‐MC‐ICP‐MS and by solution nebulisation MC‐ICP‐MS | |
| Willbold et al. | High‐precision mass‐dependent molybdenum isotope variations in magmatic rocks determined by double‐spike MC‐ICP‐MS | |
| Cava-Montesinos et al. | Room temperature acid sonication ICP-MS multielemental analysis of milk | |
| Yilmaz et al. | Ultrasound assisted-deep eutectic solvent extraction of iron from sheep, bovine and chicken liver samples | |
| Perring et al. | ED-XRF as a tool for rapid minerals control in milk-based products | |
| Barreto et al. | A novel strategy based on in-syringe dispersive liquid-liquid microextraction for the determination of nickel in chocolate samples | |
| Ma et al. | Solidified floating organic drop microextraction for determination of trace amounts of zinc in water samples by flame atomic absorption spectrometry | |
| Wang et al. | Magnetic effervescent tablet-assisted ionic liquid dispersive liquid–liquid microextraction of selenium for speciation in foods and beverages | |
| Wang et al. | Development of dispersive liquid–liquid microextraction based on solidification of floating organic drop for the determination of trace nickel | |
| CN103411968B (en) | A kind of detection method of all iron content suitable in slag | |
| Bidari et al. | Assay of total mercury in commercial food supplements of marine origin by means of DLLME/ICP-AES | |
| Barreto et al. | Pressure variation in-syringe dispersive liquid-liquid microextraction associated with digital image colorimetry: Determination of cobalt in food samples | |
| Wang et al. | Selenium speciation in rice samples by magnetic ionic liquid-based up-and-down-shaker-assisted dispersive liquid-liquid microextraction coupled to graphite furnace atomic absorption spectrometry | |
| JP5319485B2 (en) | Method and apparatus for measuring cadmium in food | |
| JP5666070B1 (en) | Sample pretreatment method for measuring the amount of harmful elements in crop samples | |
| Jalbani et al. | Determination of cadmium and lead in water and food by organic drop microextraction and flame atomic absorption spectrometry | |
| Szymczycha-Madeja et al. | Simple and fast sample preparation procedure prior to multi-element analysis of slim teas by ICP OES | |
| Yebra et al. | Automatic determination of nickel in foods by flame atomic absorption spectrometry | |
| Krejčová et al. | Determination of macro and trace element in multivitamins preparations by inductively coupled plasma optical emission spectrometry with slurry sample introduction | |
| Aydın Urucu et al. | Solidified floating organic drop microextraction for the detection of trace amount of lead in various samples by electrothermal atomic absorption spectrometry |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20151125 Termination date: 20180406 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |