GB/T5009.74-2003 Limit test of heavy metals in food additives
Test method of heavy metal ions in textiles-atomic absorption spectrophotometry
GB/T20380. 1-2006 heavy metal content of starch and its products part 1: determination of arsenic content by atomic absorption spectrometry.
GB20424-2006 Specification for Limit of Harmful Elements in Heavy Metal Concentrate Products
GB/T 17593.4-2006 determination of heavy metals in textiles part 4: atomic fluorescence spectrophotometry of arsenic and mercury.
GB/T 17593.3-2006 determination of heavy metals in textiles part 3: hexavalent chromium spectrophotometry
GB/T20380.2-2006 Heavy metal content of starch and its products Part 2: Determination of mercury content by atomic absorption spectrometry
Heavy metal content of starch and its products-Part 4: Determination of cadmium content by electrothermal atomic absorption spectrometry.
GB/T 17593. 1-2006 determination of heavy metals in textiles part 1 part: atomic absorption spectrophotometry.
Heavy metal content of starch and its products-Part 3: Determination of lead content by electrothermal atomic absorption spectrometry.
Limit and determination of 10 heavy metal elements in GB208 14-2006 dye products
Test methods for photographic chemicals Part 5: Determination of heavy metals and iron content
Determination of heavy metals in textiles-Part 2: Inductively coupled plasma atomic emission spectrometry
Determination of heavy metals in organic chemical products-Visual colorimetric method
Chemical reagent-General method for determination of heavy metals
Ammonium bicarbonate for industrial use, determination of heavy metal content, visual turbidimetric method
GB/T22930-2008 Leather and fur chemical tests-Determination of heavy metal content
GB/T23950-2009 General method for determination of heavy metals in inorganic chemical products
General method for determination of heavy metals in organic chemical products-Visual limit method
Methods for determination of ammonium bicarbonate for industrial use-Part 9: Visual turbidimetric method for heavy metal content
Chemical reagent-General method for determination of heavy metals
GB/T10304.11-1988 Determination of Heavy Metals in Cathode Carbonate
GB/T 12684.8- 1990 determination of heavy metal content in industrial boric acid
Gb/t13216.12-1991glycerol test method heavy metal limit test.
The relevant standards for heavy metals are basically here. If you can't find the desired standard, please consult the experts of the certification network immediately.
Many heavy metals in food are difficult for us to find with the naked eye. Many food additives contain too much heavy metals. If we eat too much, heavy metals in the human body contain
The quantity will exceed the standard. You need food heavy metal detection!
According to reports, lead ion is a major environmental pollutant, which is carcinogenic and extremely harmful to human health and ecological environment. The traditional detection methods are mainly chromatography and mass spectrometry, but these methods are troublesome to operate and require expensive instruments, which limits their wide application.
Guangzhou Institute of Biomedicine and Health, China Academy of Sciences, established a new detection method for heavy metals in food.
Non-enzyme signal ultra-sensitive detection amplification test strip for lead ion detection. The principle is that when lead ions exist, the cut DNA enzyme substrate chain will start a series of DNA self-assembly processes, thus achieving the purpose of signal amplification.
The newly applied test strip has high sensitivity and can detect 10pM lead ion. This value is far below the maximum allowable amount of lead ions in drinking water of 72nM stipulated by the US Environmental Protection Agency.
Experts in the industry said that the non-enzymatic signal amplification test strip is simple to operate and does not need to use testing instruments, so it is a rapid and sensitive detection of heavy metal lead pollution in the environment.
Detection provides an effective means, reduces the detection cost and has important application value in the field of environmental heavy metal detection.
We are often exposed to lead ions, which enter our bodies with food. Food heavy metal detection can detect the content of lead ions in food and keep you away from lead poisoning!
Heavy metal pollution mainly comes from industrial pollution, followed by traffic pollution and domestic garbage pollution. Industrial pollution is mostly discharged into the environment through waste residue, waste water and waste gas, which is enriched in people, animals and plants, thus causing great harm to the environment and human health. The treatment of industrial pollution can reduce its pollution through some technical methods and management measures, and finally reach the national pollutant discharge standard; Traffic pollution is mainly caused by cars.
Detection of heavy metals in food
The state has formulated a series of management measures for automobile exhaust emission, such as: using ethanol gasoline and installing automobile exhaust purifier; Household pollution
Mainly some domestic garbage pollution, waste batteries, broken lamps, unused cosmetics, glazed plates and so on. As long as the heavy metal pollution is controlled from the source, it can be reduced more or less.
Experts pointed out that at present, the backward research and development of technology, equipment and technology in China's plastic production enterprises is the main cause of serious pollution, while poor management, local protection and people's weak awareness of environmental protection have aggravated the pollution and need to be strengthened. Production enterprises should look to the future, advocate environmental protection and use environmental additives to make the PVC industry develop healthily and long-term.
Recognized analytical methods for heavy metals include: microscopic spectrometry (MS), ultraviolet spectrophotometry (UV), atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS), inductively coupled plasma method (ICP), X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). In addition to the above methods, microscopic spectroscopy technology also introduces spectral technology for detection, which is more precise and accurate!
Inductively coupled plasma mass spectrometry (ICP-MS) is used in Japan and some countries in the European Union, but for domestic users, the instrument cost is high. Some also use X-ray fluorescence spectroscopy (XRF) analysis, which has the advantages of nondestructive testing and direct analysis of finished products, but the detection accuracy and repeatability are not as good as spectral analysis. The latest popular detection method, anodic stripping method, has fast detection speed and accurate value, and can be used for on-site environmental emergency detection.
(1) atomic absorption spectrometry
Atomic absorption spectrometry is a new instrumental analysis method founded in 1950s. It supplements atomic emission spectrometry, which is mainly used for qualitative analysis of inorganic elements, and becomes the main means for quantitative analysis of inorganic compounds.
The flow of atomic absorption analysis is as follows: 1. Make the sample into solution (blank at the same time); 2. Prepare a series of calibration solutions (standard samples) with known concentrations of sub-elements; 3. Measure the corresponding values of blank and standard samples in turn; 4. Draw a calibration curve according to the corresponding values; 5. Measure the corresponding value of the unknown sample; 6. Calculate the concentration value of the sample according to the calibration curve and the corresponding value of the unknown sample.
Now, due to the development of computer technology and chemometrics and the appearance of many new components, the precision, accuracy and automation of atomic absorption spectrometer have been greatly improved. The atomic absorption spectrometer controlled by microprocessor simplifies the operation procedure and saves the analysis time. At present, gas chromatography and atomic absorption spectrometry have been successfully developed, which further expands the application field of atomic absorption spectrometry.
(2) UV-Vis spectrophotometry
The detection principle is that heavy metals and chromogenic agents-usually organic compounds-can complex with heavy metals to form colored molecular groups, and the color depth of the solution is directly proportional to the concentration. At a specific wavelength, colorimetric detection is carried out.
There are two kinds of spectrophotometric analysis, one is to measure the absorption of ultraviolet and visible light by the substance itself; The other is to generate colored compounds, that is, "color development", and then determine. Although many inorganic ions have absorption in ultraviolet and visible light regions, they are rarely directly used for quantitative analysis because of their weak strength. Adding chromogenic agent to convert the substance to be detected into a compound that can absorb under ultraviolet and visible light for photometric determination, which is the most widely used testing method at present. Color developers are divided into inorganic color developers and organic color developers, and organic color developers are used more. Most organic color developers are colored compounds themselves, and the compounds generated by the reaction with metal ions are generally stable chelates. The color reaction has high selectivity and sensitivity. Some colored chelates are easily soluble in organic solvents and can be detected by colorimetry after extraction and leaching. In recent years, the color system of multicomponent complexes has attracted extensive attention. Multicomponent complex refers to a complex formed by three or more components. The formation of multicomponent complexes can improve the sensitivity of spectrophotometric determination and improve the analytical characteristics. In recent years, in pretreatment, extraction and colorimetric detection, there have been differences in the selection and use of chromogenic agents.
Important research topic of spectrophotometry.
(3) Atomic fluorescence spectrometry
Atomic fluorescence spectrometry (AFS) is a method to determine the content of the elements to be measured by measuring the fluorescence emission intensity of atomic vapor of the elements to be measured under the excitation of radiation energy at a specific frequency.
Although atomic fluorescence spectrometry is emission spectrometry, it is closely related to atomic absorption spectrometry. It has the advantages of atomic emission spectrometry and atomic absorption spectrometry, and overcomes the disadvantages of the two methods. Atomic fluorescence spectroscopy has the advantages of simple emission line and higher sensitivity than atomic absorption light.
Spectroscopy has the characteristics of wide linear range and less interference, and can be used for the simultaneous determination of various elements. Atomic fluorescence spectrometer can be used to analyze mercury, arsenic, antimony,
Bismuth, selenium, tellurium, lead, tin, germanium, cadmium and zinc.
1 1
Some kind of element. Now it has been widely used in environmental monitoring, medicine, geology, agriculture, drinking water and other fields.
Among the national standards, atomic fluorescence spectrometry has been regarded as the first choice for the determination of arsenic, mercury and other elements in food.
After the gaseous free atoms absorb the radiation with characteristic wavelength, the outer atoms
electron
From the ground state or low energy state, it will jump to the high energy state and emit the same at the same time.
Atomic fluorescence is energy radiation with the same or different original excitation wavelengths. Emission intensity of atomic fluorescence
if
And element in unit volume in atomizer.
Atomic number of ground state
ordinary
In direct proportion. When the atomization efficiency and fluorescence quantum efficiency are fixed, the atomic fluorescence intensity is proportional to the sample concentration.
Detection of heavy metals in food
At present, an atomic fluorescence spectrometer for simultaneous determination of multiple elements has been developed, which uses multiple high-intensity hollow cathode lamps as light sources and has high
Inductively coupled plasma temperature (
Inductively Coupled Plasma
As an atomizer, multiple elements can be atomized at the same time. Multi-element analysis system based on
Inductively Coupled Plasma
Taking the atomizer as the center, a plurality of detection units are installed around it, which correspond to the hollow cathode lamp at right angles, and the generated fluorescence is detected by the photomultiplier tube.
Measure. The electrical signal after photoelectric conversion is amplified by computer, and the analysis results of each element are obtained.
(4) Electrochemical method-anodic stripping voltammetry.
Electrochemical method is a method that has developed rapidly in recent years. It is based on classical polarography, on which polarography, anode and cathode are derived.
Polarographic stripping voltammetry and other methods. Electrochemical method has low detection limit and high sensitivity, which is worth popularizing and applying. Such as the determination method of lead in national standard.
The fifth and second methods for the determination of chromium are oscillopolarography.
Anodic stripping voltammetry is an electrochemical analysis method which combines potentiostatic electrolytic enrichment with voltammetry. This method can be connected once.
Continuous determination of various metal ions has high sensitivity and can be determined.
10-7- 10-9 mol/l
Metal ions. The instruments used in this method are relatively simple, fuck.
This is a convenient trace analysis method. Anodic stripping voltammetry, which is suitable for the determination of metal impurities in chemical reagents, has been promulgated in China.
National standards.
Anodic stripping voltammetry is divided into two steps. The first step is "electrodeposition", that is, under constant potential, the ions to be detected are enriched by electrodeposition.
The mercury collect on that working electrode and the mercury on the electrode generate amalgam. For a given metal ion, if the stirring speed is constant and the pre-electrolysis time is fixed, then
m=Kc
That is to say, the amount of electrodeposited metal is directly proportional to the concentration of the metal to be measured.
The second step is "dissolution",
That is, after concentration,
General stillness
30 seconds
or
60 s
Then, a reverse voltage is applied to the working electrode, and by scanning from negative to positive, the metal in the amalgam is re-oxidized into ions and returned to the solution.
Generating an oxidation current,
Recording voltage
-
Current curve,
Namely volt-ampere curve.
The curve has a peak shape,
The peak current is proportional to the measured concentration in the solution,
It can be used as the basis for quantitative analysis, and the peak potential can be used as the basis for qualitative analysis.
Oscillopolarography is also called "single sweep polarography". A new polarographic analysis method. This is a polarographic method for rapidly increasing electrolytic voltage.
Law. Usually, at the late growth stage of each mercury drop at the mercury drop electrode, a sawtooth pulse voltage is quickly applied to the two poles of the electrolytic cell, which is obtained in a few seconds.
A polarogram, in order to quickly record polarogram, usually uses the screen of oscilloscope tube as a display tool, so it is called oscillopolarography. Its advantages are:
Fast and sensitive.
(5)
X
X-ray fluorescence spectrometry (
x ray fluorescence
)
X
X-ray fluorescence spectrometry is the use of sample pairs
x
The absorption of radiation varies with the components in the sample, and the degree of change can be determined qualitatively or quantitatively.
A method of sample synthesis. It has the advantages of fast analysis speed, simple sample pretreatment, wide range of analyzable elements, simple spectral lines, less spectral interference,
Specimen morphological diversity and nondestructive testing. It can be used not only for qualitative and quantitative analysis of constant elements, but also for trace analysis.
The detection limit of most elements can be reached.
10-6
. Combined with separation and enrichment, it can achieve
10-8
. The range of elements measured includes the period.
From the table
F-U
All the elements of. Multi-channel analyzer can measure simultaneously in a few minutes.
20
The content of various elements.
x
X-ray fluorescence method can not only analyze massive samples, but also analyze the composition and film thickness of each layer of multilayer coatings.
When the sample is subjected to
x
When irradiated by rays, high-energy particle beams, ultraviolet rays, etc. Due to the collision between high-energy particles or photons and sample atoms, atoms will
Layer electrons are expelled to form holes, leaving atoms in excited States. The lifetime of this excited ion is very short, and there are many when the outer electrons jump to the inner holes.
The rest of the energy is in
x
The form of radiation is released, creating new holes and new ones in the outer layer of teaching.
x
Radiation emission, producing a series of
trait
x
Ray. trait
x
Ray is inherent in various elements and is related to the atomic coefficient of elements. So as long as the features are measured,
x
Ray wave
long
λ
, you can find the element that produces the wavelength. You can do qualitative analysis. The composition of the sample is uniform, the surface is smooth and flat, and there is no interaction between elements.
Under the excitation condition, when in use
x
Ray (once
x
X-ray) is used as an excitation source to irradiate the sample, so that the elements in the sample have characteristics.
x
X-ray (fluorescence)
x
shoot
Line), if the elements are the same as the experimental conditions, fluorescence
x
There is a linear relationship between the ray intensity and the content of analytical elements. Depending on the intensity of the spectral line
Conduct quantitative analysis.
(6) Inductively coupled plasma mass spectrometry (
Inductively coupled plasma mass spectrometry
)
Inductively coupled plasma mass spectrometry
The detection limit is impressive,
The detection limit of its solution is mostly
ppt
Level,
The actual detection limit cannot be better than yours.
The cleanliness of the laboratory.
It must be pointed out that,
Inductively coupled plasma mass spectrometry
about
ppt
The liquid level detection limit is applicable to simple solutions containing a small amount of dissolved substances.
Ruoshe
And the detection limit of the concentration in the solid, because
Inductively coupled plasma mass spectrometry
Poor salt tolerance,
Inductively coupled plasma mass spectrometry
The advantages of detection limit will be reduced.
50
Times, some ordinary.
Light elements (e.g.
S
、
calcium (Ca)
、
Continuing education (UK)
、
K
、
selenium
) at
Inductively coupled plasma mass spectrometry
There is serious interference, which will also worsen its detection limit.
Inductively coupled plasma mass spectrometry
As an ion source
Inductively Coupled Plasma
Torch, interface device and mass spectrometer as detector.
Inductively coupled plasma mass spectrometry
The ionization source use is inductively coupled plasma (
Inductively Coupled Plasma
)
Its main body is a torch tube composed of three layers of timely sleeves, which
Detection of heavy metals in food
The end of the tube is wound with a load coil, and the three-layer tube is filled with carrier gas, auxiliary gas and cooling gas from inside to outside, and the load coil is vertically coupled by a high-frequency power supply.
The magnetic field is perpendicular to the plane of the coil. If argon is ionized by a high-frequency device, argon ions and electrons will react with other argon atoms under the action of electromagnetic field.
Collisions produce more ions and electrons,
Form a vortex.
Strong current produces high temperature,
The argon formation temperature can be reach immediately.
1000k
blood plasma
A torch. The sample to be analyzed is usually in the following form
aqueous solution
It is introduced into argon flow in the form of aerosol, and then enters the atmosphere under the excitation of radio frequency energy.
In the central region of argon plasma, the high temperature of the plasma makes the sample desolvate, evaporate and ionize. Part of the plasma passes through different pressure zones.
Entering the vacuum system, positive ions are pulled out and separated according to the mass-to-charge ratio. About above the load coil
10mm
place
,
Torch temperature
about
8000K，
At such a high temperature
,
Ionization energy is lower than
7eV
The elements of are completely ionized, and the ionization energy is lower than that of.
10.5 ev
The ionization degree of the element is greater than.
20%
. Because the ionization energy of most important elements is lower than that of other elements
10.5 ev
, so they all have high sensitivity, and there are a few elements with high ionization energy, such as
C
O
chlorine
bromine
It can also be detected, but the sensitivity is low.