CN101349640A - Method for detecting chrome in milk and dairy product - Google Patents
Method for detecting chrome in milk and dairy product Download PDFInfo
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- CN101349640A CN101349640A CNA2008102122953A CN200810212295A CN101349640A CN 101349640 A CN101349640 A CN 101349640A CN A2008102122953 A CNA2008102122953 A CN A2008102122953A CN 200810212295 A CN200810212295 A CN 200810212295A CN 101349640 A CN101349640 A CN 101349640A
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Abstract
The invention relates to a method for testing chromium in milk and milk products, which comprises the following steps: firstly, preparing a plurality of chromium standard solution with different concentrations, respectively testing the chromium standard solution, drawing the standard curve diagram between the content of chromium and the testing result according to the data which are measured, secondly, testing samples with the same method, and getting a testing result, thirdly, comparing the testing result in the step two with the stand curve diagram, and getting the content of chromium in the samples. The check out test set which is used in testing is an atomic absorption spectrophotometer of a graphite oven iron. The samples are tested after ashing and digesting by 5% nitric acid, the ashing temperature is 800 DEG C, and the atomization temperature is 2600 DEG C. The correlation coefficient reaches more than 0.999 in 0.0-10.0ng/ml linear range, and the coefficient of recovery is 88.1%-96.9%. Matrix modifier is not needed to be added in the method. The utility model has the advantages of high sensitiveness, little reagent dosage, little disturbance and the like, which is simple and fast.
Description
Technical field
The present invention relates to chromium content detecting method in the detection method of chromium in a kind of food, particularly milk and milk products, belong to analysis technical field.
Background technology
Chromium is the trace element of needed by human, brings into play special role in the glycometabolism of human body and lipid metabolism.The chromium of trivalent is the element to the human body beneficial, and sexavalent chrome is poisonous.Human body is extremely low to the absorption rate of inorganic chromium, less than 1%; Human body can reach 10-25% to the utilization factor of Organic Chromium.The content of chromium in wholefood is lower, all the form with trivalent exists.Exactly, the physiological function of chromium is that the material with other control metabolism cooperates and works, as the genetic stew (DNA and RNA) of hormone, insulin, various enzyme, cell etc.The physiological function of chromium mainly contains: 1. GTF (glucose tolerance factor, important composition composition GTF) in the body; 2. influence lipid metabolism; 3. promote protein metabolism and grow.
Because chromium and compound thereof are widely used in industry such as chemical industry, plating, printing and dyeing.It is often with dust, steam, waste water formation contaminated air, water source and crops, and therefore excessive chromium is also very important to the mankind's harm.Chromium mainly is by due to the hexavalent chromium compound to the harm of human body.The aqueous solution of solubility sexavalent chrome oxide---the toxicity of the pure and mild chromium alkoxide of chromium is bigger, and has pungency and corrosivity.Chromium can absorb through skin, and useful chromic acid is treated wart or burnt the report that hemorrhoid cause poisoning, and chromium can influence oxidation, reduction and hydrolytic process in vivo, and too much chromium can make protein denaturation, nucleic acid and nucleoprotein precipitation, enzyme system be disturbed.Chromium also is a kind of more common sensitizer.Chromic acid and chromate cause that the symptom of poisoning is dysphagia, upper abdomen burn feeling, diarrhoea, blood watery stool, and shock, livid purple, expiratory dyspnea appear in severe patient, and the central nervous system symptom can appear in the baby.
Zoopery proves that plumbous chromate, zinc chromate, sodium bichromate etc. have carcinogenicity.Industrially developed country such as American and Britain, moral, day confirm through investigation such as epidemic diseases, produce with chrome ore among the workman of dichromate, and the lung cancer morbidity rate is a lot, is called " chromium lung cancer ".
Treatment to chromium poisoning does not still have specific short at present, generally is anti symptom treatment.Therefore, need seek easy, quick, accurately detect the method for chromium allowance in the milk and milk products, could satisfy the strict day by day residual requirement of limiting the quantity of, thereby guarantee the health and the safety of the edible milk and milk products of people.
Detect the common method of chromium spectrophotometric method, atomic absorption method and electrochemical methods etc. are arranged, wherein traditional spectrophotometric method insufficient sensitivity, when hanging down chromium content, flame atomic absorption method can not accurately measure, GFAAS (graphite furnace atomic absorption spectrometry) is highly sensitive, detection limit is low, is chromium content analysis prefered method.
" GFAAS (graphite furnace atomic absorption spectrometry) is measured the content of chromium in the dairy products " (" Food Additives Used in China " 2006 03 phases, the 151-154 page or leaf, Hao Yanping, high U.S. is beautiful, Wang Kexin) a kind of method of using chromium content in the aas determination dairy products is disclosed, but this method is added the matrix modifier diammonium hydrogen phosphate, adopt the graphite-pipe platform technology and match graceful background deduction technology and reduce calcium, the isoionic interference of iron, in testing process, need all implement this step to sample and blank assay, its experimental procedure is comparatively complicated, and test speed is slow, reagent dosage is more.
Summary of the invention
The objective of the invention is to obtain heavy metal chromium content detecting method in a kind of milk and milk products, have easy, quick, sensitive, need not to add matrix modifier, advantage that reagent dosage is little.
The detection method of heavy metal chromium of the present invention comprises the steps:
1) chromium standard solution of a plurality of variable concentrations of preparation, and it is detected respectively, according to measured data, draw the content of chromium and the canonical plotting between the testing result;
2) sample is used the same method detect, and obtain testing result;
3) with step 2) in testing result and described canonical plotting comparison, promptly obtain the content of chromium in the sample.
Employed checkout equipment is the sampling Graphite Furnace Atomic Absorption spectrophotometer.
Preferably, the heavy metal chromium standard solution of a plurality of variable concentrations described in the step 1) is: 10.0ng/mL, 8.0ng/mL, 6.0ng/mL, 4.0ng/mL, 2.0ng/mL, the standard solution of 0.0ng/mL.
Among the present invention, above-mentioned step 2) disposal route of sample is as follows in:
A) take by weighing sample 1g-5g in porcelain crucible, charing moves in the muffle furnace to smokeless on electric hot plate, 490 ℃ of ashing 8 hours, cooling;
B) use salpeter solution, preferably use 5% nitric acid 25mL, dissolve the particle after the above-mentioned ashing and be settled to 25mL, mixing obtains solution to be measured.
If the individual sample ashing is not thorough, at step a) and b) between, add acid mixture (1: 4, perchloric acid: nitric acid) little fire on the electric hot plate be heated to do after again ashing to there not being black particle;
In above-mentioned detection, the spectrophotometric ashing temperature of sampling Graphite Furnace Atomic Absorption is 800 ℃, 2600 ℃ of atomization temperatures.
Preferably, above-mentioned sampling Graphite Furnace Atomic Absorption spectrophotometer condition of work is as follows:
Wavelength 359.3nm, slit 1.3nm, lamp current 7.5mA, baking temperature 50-140 ℃, 45s, 800 ℃ of ashing temperature, 15s, 2600 ℃ of atomization temperatures, 5s, 2700 ℃ of purification temperatures, 4s, cool time 15s, sampling volume 20 μ L.
Its heating schedule is as follows:
Chromium detection method of the present invention has following advantage:
1) the detection step is easy, quick.
2) highly sensitive, detection limit only is 0.2ng/mL, can satisfy international and domestic to the particularly detection requirement of Determination of Trace Chromium content of chromium content.
3) under condition of the present invention, need not add matrix modifier, strong to the selectivity of target compound, disturb and lack, accurate quantification, reagent dosage is few.
4) testing result good linearity, the precision height, in the experimental concentration scope, correlation coefficient r can reach more than 0.999 in the present invention, the recovery is between 88.1%-96.9%, and in a few days the relative standard deviation (RSD) with the day to day precision experiment is respectively 1.83% and 2.09%.
Description of drawings
Fig. 1 is the absorbance variation diagram under 400 ℃ of-1100 ℃ of different ashing temperature in one embodiment of the present of invention.
Fig. 2 is the light absorption value variation diagram under 2000 ℃ of-2750 ℃ of different atomization temperatures in one embodiment of the present of invention.
Fig. 3 is in one embodiment of the present of invention, the absorbance variation diagram under the 1%-5% concentration salpeter solution condition.
Fig. 4 is in one embodiment of the present of invention, does not add improver and the absorbance comparison diagram that adds improver.
Fig. 5 is improver absorbance figure during different sample size in one embodiment of the present of invention.
Fig. 6 is the chromium canonical plotting of one embodiment of the present of invention.
Fig. 7 is the chromium canonical plotting of another embodiment of the present invention.
Fig. 8 is the chromium canonical plotting of another embodiment of the present invention.
Embodiment
Below in conjunction with specific embodiments method of the present invention is done more detailed description.It will be appreciated by those skilled in the art that following embodiment all is used for the present invention's scope required for protection is carried out the description of exemplary, summarize the relative scope of each parameter of the present invention, thereby it can not be interpreted as a kind of concrete restriction of the present invention with this.
1, reagent and instrument:
1) preparation of standard solution:
The accurate 1.0mg/ml (GBW (E) 080117, State Standard Matter Research Centre) that draws uses the ultrapure water constant volume in the 100mL volumetric flask, mixing, obtaining chromium standard solution concentration is the standard inventory solution of 100ng/mL, is positioned over-18 ℃ of refrigerators and keeps in Dark Place, and can preserve for 4 week at least.During use, the nitric acid with 5% is diluted to 10.0ng/mL, 8.0ng/mL, 6.0ng/mL, 4.0ng/mL, the standard solution of 2.0ng/mL.
2) instrument: the Z-2000 of Hitachi atomic absorption graphite furnace spectrophotometer
2, the selection of drying program
Easy bumping sputter when making sample drying arrive near 100 ℃ of left and right sides so earlier at the most of free moisture of 50 ℃ of preliminarily drieds, be heated to 140 ℃ in the slope mode again, keeps 25s.
The selection of 3, ashing temperature
Adopt coating graphite tube (Hitachi, Ltd), atomization temperature is fixed as 2600 ℃, the ashing temperature is set 400 ℃, 500 ℃, 600 ℃, 700 ℃, 800 ℃, 900 ℃, 1000 ℃, 1100 ℃ respectively, the standard chlorine measured in solution absorbance that adds 10ng/mL to atomic absorption graphite furnace spectrophotometer, experimental result as shown in Figure 1, as seen ashing temperature is the absorbance maximum in the time of 800 ℃, favorable reproducibility.Higher ashing temperature and enough ashing time can make the ashing of sample liquid complete, down select the different ashing times to detect at 800 ℃, when the ashing time reach 10s when above absorbance keep stable, according to actual conditions ashing selection of time 15s.
4, the selection of atomization temperature
The ashing temperature is set at 800 ℃, atomization temperature is set 2000 ℃, 2100 ℃, 2200 ℃, 2300 ℃, 2400 ℃, 2500 ℃, 2600 ℃, 2700 ℃, 2750 ℃ respectively, the atomization time is 5s, adds the standard chlorine measured in solution absorbance of 10ng/mL to atomic absorption graphite furnace spectrophotometer.Experimental result as shown in Figure 2, atomization efficiency is the highest in the time of 2600 ℃, absorbance is the highest for visible atomization temperature, repeatedly the favorable reproducibility of measurement result.
5, the selection of concentration of nitric acid
The ashing temperature is set at 800 ℃, atomization temperature is set at 2600 ℃, prepare the standard chlorine solution of the 10ng/mL of the nitric acid that contains 1%, 2%, 3%, 4%, 5%, 6% concentration respectively, add atomic absorption graphite furnace spectrophotometer, measure absorbance, experimental result as shown in Figure 3, visible concentration of nitric acid is the highest and stable at 5% o'clock absorbance.
6, the selection of matrix modifier
Preparation contains the standard chlorine solution of the 10ng/mL of 5% nitric acid, to not adding the improver diammonium hydrogen phosphate and adding phosphoric acid hydrogen two ammonium matrix modifier (concentration 20g/L aqueous solution, sample size 10ul) sample adds atomic absorption graphite furnace spectrophotometric determination absorbance and (the ashing temperature is set at 800 ℃, atomization temperature is set at 2600 ℃, under above-mentioned instrument condition of work,) experimental result as shown in Figure 4, as seen its absorbance of sample that adds improver among the figure is high more a lot of than the sample absorbance that does not add improver, shows that may there be interference in improver itself to measurement result.
Experimentize thus, and then to the situation of the improver that adds various dose.Under above-mentioned experiment condition, (do not add 5% nitric acid this moment), add the diammonium hydrogen phosphate 20g/L aqueous solution of 10 μ L and 20 μ L respectively, 2600 ℃ of atomization temperatures, measure absorbance, the result as shown in Figure 5, the absorbance behind the interpolation diammonium hydrogen phosphate and the proportional relation of sample size of diammonium hydrogen phosphate this shows that matrix modifier contains disturbing factor under above-mentioned experiment condition.Under above-mentioned experiment condition, added diammonium hydrogen phosphate, can cause the canonical plotting of chromium not to be linear on the contrary, the result is inaccurate.
The main chaff element that graphite furnace method is measured the chromium in breast and the dairy products have calcium, chlorine, iron, sodium plasma, the compound of these ions and the boiling point of hydride all are lower than 2600 ℃, when being brought up to 2600 ℃, atomization temperature can all eliminate the disturbing factor of these elements, so need not to add improver.And the boiling point of chromium element is greater than 2600 ℃, so 2600 ℃ atomization temperature is to the not influence of detection of element to be measured.
7, recovery experiment
Under these conditions, milk is carried out basic, normal, high varying level mark-on reclaim detection, test findings sees Table 1.
Table 1
8, precision experiment
Prepare basic, normal, high three concentration chromium mark liquid respectively, each concentration determination 6 times is calculated relative standard deviation, result such as table 2.
Table 2
In addition, absorption intensity height, the sensitivity of instrument condition of work wavelength element to be measured when the 359.3nm wavelength are good, so select the 359.3nm wavelength.
1) preparation of standard solution:
The accurate 1.0mg/ml (GBW (E) 080117, State Standard Matter Research Centre) that draws uses the ultrapure water constant volume in the 100mL volumetric flask, mixing, obtaining chromium standard solution concentration is the standard inventory solution of 100ng/mL, is positioned over-18 ℃ of refrigerators and keeps in Dark Place, and can preserve for 4 week at least.During use, the nitric acid with 5% is diluted to 10.0ng/mL, 8.0ng/mL, 6.0ng/mL, 4.0ng/mL, the standard solution of 2.0ng/mL.
2) preparation of reagent:
The preparation of 5% nitric acid: measure 25.00mL red fuming nitric acid (RFNA) (top grade is pure), slowly inject the beaker that the 200mL pure water is arranged approximately, move into after cooling in the volumetric flask of 500mL, use the pure water constant volume, mixing, standby.
3) preparation of sample:
Take by weighing sample 4.9960g in porcelain crucible, charing moves in the muffle furnace to smokeless on electric hot plate, 490 ℃ of ashing 8 hours, and cooling.With 5% salpeter solution dissolving and be settled to 25mL, obtain solution to be measured.Make reagent blank simultaneously.Last atomic absorption graphite furnace spectrophotometer is analyzed.
4) graphite oven atomic absorption instrument condition of work is as follows:
Wavelength 359.3nm, slit 1.3nm, lamp current 7.5mA, baking temperature 50-140 ℃ 45s, 800 ℃ of 15s of ashing temperature, 2600 ℃ of 5s of atomization temperature, 2700 ℃ of 4s of purification temperature.Sampling volume 20 μ L.The graphite furnace heating schedule is as follows:
5) detect step:
A) drafting of typical curve: the chromium standard solution that utilizes atomic absorption graphite furnace spectrophotometric determination variable concentrations.Shown in its typical curve Fig. 6, its horizontal ordinate is concentration (ng/mL), and ordinate is represented the size of absorbance.
B) sample determination:
Inject the atomic absorption spectrophotometer (AAS) graphite furnace, absorb the 359.3nm resonance line behind the electric atomizing, in the finite concentration scope, its absorption value is directly proportional with chromium content, more quantitatively obtain the content 0.00ng/mL of chromium in the blank sample liquid with standard series, the concentration 1.82ng/mL of chromium in the sample liquid, be inserted in equation with the result:
Chromium content in the X-sample (mg/kg or mg/L);
C-sample digestive juice is measured concentration (ng/ml);
c
0-reagent blank liquid is measured concentration (ng/ml);
M-sample mass or volume (g or ml);
V-sample digestive juice cumulative volume (ml);
Result of calculation keeps two position effective digitals.
The chromium content that calculates in the milk sample according to aforesaid equation is 0.0091mg/kg.
1) preparation of standard solution:
The accurate 1.0mg/ml (GBW (E) 080117, State Standard Matter Research Centre) that draws uses the ultrapure water constant volume in the 100mL volumetric flask, mixing, obtaining chromium standard solution concentration is the standard inventory solution of 100ng/mL, is positioned over-18 ℃ of refrigerators and keeps in Dark Place, and can preserve for 4 week at least.During use, the nitric acid with 5% is diluted to 10.0ng/mL, 8.0ng/mL, 6.0ng/mL, 4.0ng/mL, the standard solution of 2.0ng/mL.
2) preparation of reagent:
(a) preparation of 5% nitric acid:
Measure 25.00mL red fuming nitric acid (RFNA) (top grade is pure), slowly inject the beaker that the 200mL pure water is arranged approximately, move into after cooling in the volumetric flask of 500mL, use the pure water constant volume, mixing, standby.
3) preparation of sample:
Take by weighing sample 4.8021g in porcelain crucible, charing moves in the muffle furnace 490 ℃ of ashing 8 hours, cooling to smokeless on electric hot plate.With 5% salpeter solution dissolving and be settled to 25mL.Make reagent blank simultaneously, obtain solution to be measured.Last atomic absorption graphite furnace spectrophotometer is analyzed.
4) graphite oven atomic absorption instrument condition of work is as follows:
Wavelength 359.3nm, slit 1.3nm, lamp current 7.5mA, baking temperature 50-140 ℃ 45s, 800 ℃ of 15s of ashing temperature, 2600 ℃ of 5s of atomization temperature, 2700 ℃ of 4s of purification temperature.Sampling volume 20 μ L.The graphite furnace heating schedule is as follows:
5) detect step:
A) drafting of typical curve: the chromium standard solution that utilizes atomic absorption graphite furnace spectrophotometric determination variable concentrations.Shown in its typical curve Fig. 7, its horizontal ordinate is concentration (ng/mL), and ordinate is represented the size of absorbance.
B) sample determination: inject the atomic absorption spectrophotometer (AAS) graphite furnace, absorb the 359.3nm resonance line behind the electric atomizing, in the finite concentration scope, its absorption value is directly proportional with chromium content, more quantitatively obtain the content 0.00ng/mL of chromium in the blank sample liquid with standard series, the concentration 1.54ng/mL of chromium in the sample liquid, be inserted in equation with the result:
Chromium content in the X-sample (mg/kg or mg/L);
C-sample digestive juice is measured concentration (ng/ml);
c
0-reagent blank liquid is measured concentration (ng/ml);
M-sample mass or volume (g or ml);
V-sample digestive juice cumulative volume (ml);
Result of calculation keeps two position effective digitals.
The chromium content that calculates in the milk sample according to aforesaid equation is 0.0080mg/kg.
1) preparation of standard solution:
The accurate 1.0mg/ml (GBW (E) 080117, State Standard Matter Research Centre) that draws uses the ultrapure water constant volume in the 100mL volumetric flask, mixing, obtaining chromium standard solution concentration is the standard inventory solution of 100ng/mL, is positioned over-18 ℃ of refrigerators and keeps in Dark Place, and can preserve for 4 week at least.During use, the nitric acid with 5% is diluted to 10.0ng/mL, 8.0ng/mL, 6.0ng/mL, 4.0ng/mL, the standard solution of 2.0ng/mL.
2) preparation of reagent:
(a) preparation of 5% nitric acid:
Measure 25.00mL red fuming nitric acid (RFNA) (top grade is pure), slowly inject the beaker that the 200mL pure water is arranged approximately, move into after cooling in the volumetric flask of 500mL, use the pure water constant volume, mixing, standby.
3) preparation of sample:
Take by weighing sample 1.4634g in porcelain crucible, charing is to smokeless on electric hot plate, moves in the muffle furnace 490 ℃ of ashing 8 hours, and the sample ashing is not thorough, then add 1mL acid mixture (1: 4, perchloric acid: nitric acid) little fire on the electric hot plate be heated to do after again ashing to there not being black particle; Cooling.With 5% salpeter solution dissolving and be settled to 25mL, obtain solution to be measured.Make reagent blank simultaneously.Last atomic absorption graphite furnace spectrophotometer is analyzed.
4) graphite oven atomic absorption instrument condition of work is as follows:
Wavelength 359.3nm, slit 1.3nm, lamp current 7.5mA, baking temperature 50-140 ℃ 45s, 800 ℃ of 15s of ashing temperature, 2600 ℃ of 5s of atomization temperature, 2700 ℃ of 4s of purification temperature.Sampling volume 20 μ L.The graphite furnace heating schedule is as follows:
5) detect step:
A) drafting of typical curve: the chromium standard solution that utilizes atomic absorption graphite furnace spectrophotometric determination variable concentrations.Shown in its typical curve Fig. 8, its horizontal ordinate is concentration (ng/mL), and ordinate is represented the size of absorbance.
B) sample determination: inject the atomic absorption spectrophotometer (AAS) graphite furnace, absorb the 359.3nm resonance line behind the electric atomizing, in the finite concentration scope, its absorption value is directly proportional with chromium content, more quantitatively obtain the content 0.00ng/mL of chromium in the blank sample liquid with standard series, the concentration 0.98ng/mL of chromium in the sample liquid, be inserted in equation with the result:
Chromium content in the X-sample (mg/kg or mg/L);
C-sample digestive juice is measured concentration (ng/ml);
c
0-reagent blank liquid is measured concentration (ng/ml);
M-sample mass or volume (g or ml);
V-sample digestive juice cumulative volume (ml);
Result of calculation keeps two position effective digitals.
The chromium content that calculates in the sample according to aforesaid equation is 0.076mg/kg.
1) preparation of standard solution:
The accurate 1.0mg/ml (GBW (E) 080117, State Standard Matter Research Centre) that draws uses the ultrapure water constant volume in the 100mL volumetric flask, mixing, obtaining chromium standard solution concentration is the standard inventory solution of 100ng/mL, is positioned over-18 ℃ of refrigerators and keeps in Dark Place, and can preserve for 4 week at least.During use, the nitric acid with 5% is diluted to 10.0ng/mL, 8.0ng/mL, 6.0ng/mL, 4.0ng/mL, the standard solution of 2.0ng/mL.
2) preparation of reagent:
(a) preparation of 5% nitric acid:
Measure 25.00mL red fuming nitric acid (RFNA) (top grade is pure), slowly inject the beaker that the 200mL pure water is arranged approximately, move into after cooling in the volumetric flask of 500mL, use the pure water constant volume, mixing, standby.
3) preparation of sample:
Take by weighing sample 1.5891g in porcelain crucible, charing is to smokeless on electric hot plate, moves in the muffle furnace 490 ℃ of ashing 8 hours, and the sample ashing is not thorough, then add 1mL acid mixture (1: 4, perchloric acid: nitric acid) little fire on the electric hot plate be heated to do after again ashing to there not being black particle; Cooling.With 5% salpeter solution dissolving and be settled to 25mL, obtain solution to be measured.Make reagent blank simultaneously.Last atomic absorption graphite furnace spectrophotometer is analyzed.
4) graphite oven atomic absorption instrument condition of work is as follows:
Wavelength 359.3nm, slit 1.3nm, lamp current 7.5mA, baking temperature 50-140 ℃ 45s, 800 ℃ of 15s of ashing temperature, 2600 ℃ of 5s of atomization temperature, 2700 ℃ of 4s of purification temperature.Sampling volume 20 μ L.The graphite furnace heating schedule is as follows:
5) detect step:
A) drafting of typical curve: the chromium standard solution that utilizes atomic absorption graphite furnace spectrophotometric determination variable concentrations.Shown in its typical curve Fig. 8, its horizontal ordinate is concentration (ng/mL), (ordinate is represented the size of absorbance, and absorbance is the strength ratio of incident light and projection light, so there is not unit).
B) sample determination: inject the atomic absorption spectrophotometer (AAS) graphite furnace, absorb the 359.3nm resonance line behind the electric atomizing, in the finite concentration scope, its absorption value is directly proportional with chromium content, more quantitatively obtain the content 0.00ng/mL of chromium in the blank sample liquid with standard series, the concentration 0.98ng/mL of chromium in the sample liquid, be inserted in equation with the result:
Chromium content in the X-sample (mg/kg or mg/L);
C-sample digestive juice is measured concentration (ng/ml);
c
0-reagent blank liquid is measured concentration (ng/ml);
M-sample mass or volume (g or ml);
V-sample digestive juice cumulative volume (ml);
Result of calculation keeps two position effective digitals.
The chromium content that calculates in the sample according to aforesaid equation is 0.13mg/kg.
1) preparation of standard solution:
The accurate 1.0mg/ml (GBW (E) 080117, State Standard Matter Research Centre) that draws uses the ultrapure water constant volume in the 100mL volumetric flask, mixing, obtaining chromium standard solution concentration is the standard inventory solution of 100ng/mL, is positioned over-18 ℃ of refrigerators and keeps in Dark Place, and can preserve for 4 week at least.During use, the nitric acid with 5% is diluted to 10.0ng/mL, 8.0ng/mL, 6.0ng/mL, 4.0ng/mL, the standard solution of 2.0ng/mL.
2) preparation of reagent:
(a) preparation of 5% nitric acid:
Measure 25.00mL red fuming nitric acid (RFNA) (top grade is pure), slowly inject the beaker that the 200mL pure water is arranged approximately, move into after cooling in the volumetric flask of 500mL, use the pure water constant volume, mixing, standby.
3) preparation of sample:
Take by weighing sample 3.4966g in porcelain crucible, charing moves in the muffle furnace 490 ℃ of ashing 8 hours, cooling to smokeless on electric hot plate.With 5% salpeter solution dissolving and be settled to 25mL, obtain solution to be measured.Make reagent blank simultaneously.Last atomic absorption graphite furnace spectrophotometer is analyzed.
4) graphite oven atomic absorption instrument condition of work is as follows:
Wavelength 359.3nm, slit 1.3nm, lamp current 7.5mA, baking temperature 50-140 ℃ 45s, 800 ℃ of 15s of ashing temperature, 2600 ℃ of 5s of atomization temperature, 2700 ℃ of 4s of purification temperature.Sampling volume 20 μ L.The graphite furnace heating schedule is as follows:
5) detect step:
A) drafting of typical curve: the chromium standard solution that utilizes atomic absorption graphite furnace spectrophotometric determination variable concentrations.Shown in its typical curve Fig. 8, its horizontal ordinate is concentration (ng/mL), and ordinate is represented the size of absorbance.
B) sample determination: inject the atomic absorption spectrophotometer (AAS) graphite furnace, absorb the 359.3nm resonance line behind the electric atomizing, at the finite concentration model together, its absorption value is directly proportional with chromium content, more quantitatively obtain the content 0.00ng/mL of chromium in the blank sample liquid with standard series, the concentration 0.98ng/mL of chromium in the sample liquid, be inserted in equation with the result:
Chromium content in the X-sample (mg/kg or mg/L);
C-sample digestive juice is measured concentration (ng/ml);
c
0-reagent blank liquid is measured concentration (ng/ml);
M-sample mass or volume (g or ml);
V-sample digestive juice cumulative volume (ml);
Result of calculation keeps two position effective digitals.
The chromium content that calculates in the sample according to aforesaid equation is 0.10mg/kg.
Chromium detection method detection step of the present invention is easy, quick, highly sensitive, and detection limit only is 0.2ng/mL, can satisfy international and domestic to the particularly detection requirement of Determination of Trace Chromium content of chromium content.Under condition of the present invention, need not add matrix modifier, strong to the selectivity of target compound, disturb and lack, accurate quantification, reagent dosage is few.Testing result good linearity of the present invention, the precision height, in the experimental concentration scope, correlation coefficient r can reach more than 0.999 in the present invention, the recovery is between 88.1%-96.9%, and in a few days the relative standard deviation (RSD) with the day to day precision experiment is respectively 1.83% and 2.09%.
Claims (10)
1, the detection method of chromium in a kind of milk and milk products is characterized in that, comprises the steps:
1) chromium standard solution of a plurality of variable concentrations of preparation, and it is detected respectively, according to measured data, draw the content of chromium and the canonical plotting between the testing result;
2) sample is used the same method detect, and obtain testing result;
3) with step 2) in testing result and described canonical plotting comparison, promptly obtain the content of chromium in the sample.
2, detection method as claimed in claim 1 is characterized in that, the checkout equipment that uses in the described detection is the sampling Graphite Furnace Atomic Absorption spectrophotometer.
3, detection method as claimed in claim 1 is characterized in that, the heavy metal chromium standard solution of a plurality of variable concentrations described in the step 1) is: 10.0ng/mL, 8.0ng/mL, 6.0ng/mL, 4.0ng/mL, 2.0ng/mL, the standard solution of 0.0ng/mL.
4, as any described detection method among the claim 1-3, it is characterized in that: the disposal route of sample is as follows described step 2):
A) take by weighing sample in porcelain crucible, charing moves in the muffle furnace 490 ℃ of ashing 8 hours, cooling to smokeless on electric hot plate;
B) with salpeter solution dissolving and constant volume, mixing obtains solution to be measured.
5, detection method as claimed in claim 4 is characterized in that, step a) and b) between, add acid mixture (1: 4, perchloric acid: nitric acid) little fire on the electric hot plate be heated to do after again ashing to there not being black particle.
As claim 4 or 5 described detection methods, it is characterized in that 6, concentration of nitric acid is 5% in the described step b).
7, as any described detection method among the claim 4-6, it is characterized in that: the spectrophotometric ashing temperature of described sampling Graphite Furnace Atomic Absorption is 800 ℃.
8, as any described detection method among the claim 4-6, it is characterized in that: 2600 ℃ of the spectrophotometric atomization temperatures of described sampling Graphite Furnace Atomic Absorption.
9, as claim 7 or 8 described detection methods, it is characterized in that: described sampling Graphite Furnace Atomic Absorption spectrophotometer condition of work is as follows:
Wavelength 359.3nm, slit 1.3nm, lamp current 7.5mA, baking temperature 50-140 ℃, 45s, 800 ℃ of ashing temperature, 15s, 2600 ℃ of atomization temperatures, 5s, 2700 ℃ of purification temperatures, 4s, cool time 15s, sampling volume 20 μ L.
10, detection method as claimed in claim 9 is characterized in that: described graphite furnace heating schedule is as follows:
Retention time initial temperature final temperature slope time stage (s) carrier gas flux
(℃) (℃) (s) (ml·min-1)
Dry 50 140 20 25 200
Ashing 800 800 10 5 200
Atomization 2,600 2,600 05 10
Purify 2,700 2,700 04 200
Cool off 000 15 200
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| CNA2008102122953A CN101349640A (en) | 2008-09-09 | 2008-09-09 | Method for detecting chrome in milk and dairy product |
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| CNA2008102122953A CN101349640A (en) | 2008-09-09 | 2008-09-09 | Method for detecting chrome in milk and dairy product |
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| CN103424306A (en) * | 2012-05-25 | 2013-12-04 | 内蒙古蒙牛乳业（集团）股份有限公司 | Ashing method and detection method using the same |
| CN103604767A (en) * | 2013-11-26 | 2014-02-26 | 中国南方航空工业(集团)有限公司 | Method for measuring cobalt content of cutting oil |
| CN105092322A (en) * | 2014-04-23 | 2015-11-25 | 内蒙古蒙牛乳业（集团）股份有限公司 | Detection method for element content in egg yolk powder, and sample pre-treatment method thereof |
| CN105588807A (en) * | 2014-10-24 | 2016-05-18 | 内蒙古蒙牛乳业（集团）股份有限公司 | Assay method of sodium and potassium elements in dairy product |
| CN105628484A (en) * | 2014-11-05 | 2016-06-01 | 内蒙古蒙牛乳业（集团）股份有限公司 | Method for pre-treating sample used for detection of mineral matter element in feed and detection method thereof |
| CN105758812A (en) * | 2016-04-06 | 2016-07-13 | 云南新希望邓川蝶泉乳业有限公司 | Method for rapidly determining lead and chromium in dairy products |
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| CN106290180A (en) * | 2015-05-18 | 2017-01-04 | 内蒙古蒙牛乳业（集团）股份有限公司 | A kind of Pb in food, chromium, cadmium and the detection method of copper content |
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- 2008-09-09 CN CNA2008102122953A patent/CN101349640A/en active Pending
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| CN103424306A (en) * | 2012-05-25 | 2013-12-04 | 内蒙古蒙牛乳业（集团）股份有限公司 | Ashing method and detection method using the same |
| CN103604767A (en) * | 2013-11-26 | 2014-02-26 | 中国南方航空工业(集团)有限公司 | Method for measuring cobalt content of cutting oil |
| CN103604767B (en) * | 2013-11-26 | 2016-05-04 | 中国南方航空工业(集团)有限公司 | The assay method of cobalt content in cutting oil |
| CN105092322A (en) * | 2014-04-23 | 2015-11-25 | 内蒙古蒙牛乳业（集团）股份有限公司 | Detection method for element content in egg yolk powder, and sample pre-treatment method thereof |
| CN105588807A (en) * | 2014-10-24 | 2016-05-18 | 内蒙古蒙牛乳业（集团）股份有限公司 | Assay method of sodium and potassium elements in dairy product |
| CN105628484A (en) * | 2014-11-05 | 2016-06-01 | 内蒙古蒙牛乳业（集团）股份有限公司 | Method for pre-treating sample used for detection of mineral matter element in feed and detection method thereof |
| CN106198412A (en) * | 2015-05-04 | 2016-12-07 | 内蒙古蒙牛乳业（集团）股份有限公司 | The detection method of constituent content in a kind of food |
| CN106290180A (en) * | 2015-05-18 | 2017-01-04 | 内蒙古蒙牛乳业（集团）股份有限公司 | A kind of Pb in food, chromium, cadmium and the detection method of copper content |
| CN105758812A (en) * | 2016-04-06 | 2016-07-13 | 云南新希望邓川蝶泉乳业有限公司 | Method for rapidly determining lead and chromium in dairy products |
| CN109580416A (en) * | 2018-12-27 | 2019-04-05 | 中核四0四有限公司 | Residual object, total oxide measurement temperature-rising method are always steamed in a kind of high activity liquid waste |
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