CN111551538A - LIBS technology-based signal enhancement method for heavy metal detection in aquatic products - Google Patents
LIBS technology-based signal enhancement method for heavy metal detection in aquatic products Download PDFInfo
- Publication number
- CN111551538A CN111551538A CN202010370930.1A CN202010370930A CN111551538A CN 111551538 A CN111551538 A CN 111551538A CN 202010370930 A CN202010370930 A CN 202010370930A CN 111551538 A CN111551538 A CN 111551538A
- Authority
- CN
- China
- Prior art keywords
- libs
- aquatic products
- detection
- samples
- heavy metals
- 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.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
- G01N21/718—Laser microanalysis, i.e. with formation of sample plasma
Landscapes
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Biochemistry (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
Abstract
The invention discloses a signal enhancement method for detecting heavy metals in aquatic products based on LIBS technology, which comprises the steps of homogenizing fresh aquatic products in a substrate-assisted and nanoparticle-enhanced mode, extracting heavy metal elements in samples by hydrochloric acid, separating supernate after ultrasonic oscillation and centrifugation, dripping the supernate on a glass substrate coated with a nanoparticle layer on the surface, drying to form samples to be detected, optimizing experimental parameters of LIBS detection, and carrying out spectrum collection and analysis on the samples to be detected. According to the method, LIBS detection of a fresh aquatic product is converted into detection of a deposited sample on a substrate through solid-liquid-solid state conversion, and the method is combined with a nanoparticle enhancing method, so that the heavy metal detection of the aquatic product is remarkably enhanced under a common LIBS experiment system, the detection sensitivity is improved, and the detection requirement of trace toxic heavy metals in the aquatic product is met.
Description
The technical field is as follows:
the invention belongs to the technical field of spectrum detection, and particularly relates to a LIBS technology-based signal enhancement method for detecting heavy metals in aquatic products.
Background art:
the sea stores abundant biological resources, with the development and progress of fishery technology, the consumption index of aquatic products in all regions of the world is increasing day by day, and scientists regard the sea as a future granary. Compared with land meat poultry, the nutrient elements provided by aquatic organisms are similar to the composition of essential elements required by human bodies, are easier to absorb and digest by the human bodies, have a much lower nutrient saturation value, and have higher nutritional and medicinal values. Meanwhile, people are also paying more attention to the problems of diet safety and health risks brought by food consumption, and researches on the content of toxic elements in aquatic products are receiving great attention. Since the marine organisms grow in complex and various marine environments, the marine organisms are more easily influenced by environmental pollution and organism enrichment, toxic substances such as heavy metals, trace elements, persistent organic pollutants and the like can be accumulated in the bodies of the marine organisms, and the toxic substances can flow into the human bodies through food chain enrichment to destroy a plurality of organs of the human bodies. The phenomenon that heavy metal elements in various aquatic products exceed standards sometimes occurs.
The Laser Induced Breakdown Spectroscopy (LIBS) technology is an elemental analysis technology based on laser induced plasma atomic emission spectroscopy, and compared with the traditional analysis method, the method has the advantages of high detection speed, no (or small) sample pretreatment, capability of analyzing multiple elements simultaneously, capability of on-site detection and the like, and is widely applied to the detection of substances in various fields with various properties such as solid, liquid, gas and the like. In food analysis, LIBS research has focused on elemental composition analysis, contaminant analysis, and adulteration detection. Patent CN2019111383664 discloses a method for rapidly detecting the content of phosphorus in aquatic products based on a laser-induced breakdown spectroscopy technology, which realizes rapid detection of phosphorus in aquatic products. The content of toxic heavy metal elements in aquatic products is low, trace levels are achieved, and the method is difficult to directly detect. According to the regulation of GB2762-2017 pollutant limit in food, the limit standard of lead is 0.5mg/kg and the limit standard of cadmium is 0.1mg/kg for fresh and frozen fishes. Because the LIBS has relatively low sensitivity, the detection limit is high, and the detection limit of the traditional LIBS method can not meet the detection requirement of national limit standard aiming at heavy metal elements such as lead, cadmium and the like. Currently, there are several methods for laser-induced breakdown spectroscopy signal enhancement. When the patent CN110702667A is used for laser-induced breakdown spectroscopy detection, microplasmas are used as auxiliary excitation sources and act on the surface of a sample to be detected with laser simultaneously, so that LIBS signal enhancement is realized. The patent CN109507171A adopts argon-assisted surface-enhanced laser-induced breakdown spectroscopy technology, and argon atoms have a metastable state with a lower excitation energy state, so that the metastable state is easy to ionize to generate electrons, the number density of the electrons is increased, the emission spectrum intensity of plasma is improved, and the detection limit of the surface-enhanced laser-induced breakdown spectroscopy technology is improved. Patent CN109557082A adopts in-situ multiple sample preparation to assist surface-enhanced laser-induced breakdown spectroscopy, i.e. the liquid drop to be detected is circularly dropped multiple times within the range of the first prepared circular analysis layer, and is dried, so that the concentration of the element to be detected in the fixed area is increased, the LIBS signal intensity is improved, and the detection limit of the element to be detected is reduced. The invention aims to realize the LIBS detection signal enhancement of heavy metal elements in aquatic products from another angle.
The invention content is as follows:
the invention aims to design a LIBS technology-based signal enhancement method for detecting heavy metals in aquatic products, improve detection sensitivity, realize detection of trace heavy metals in aquatic products under a common LIBS experimental system, and solve the problem that the existing LIBS technology is difficult to be directly applied to detection of trace heavy metals in aquatic products.
In order to achieve the purpose, the invention relates to a signal enhancement method for detecting heavy metals in aquatic products based on LIBS technology, which comprises the steps of homogenizing fresh aquatic products in a substrate-assisted and nanoparticle-enhanced mode, extracting heavy metal elements in samples by hydrochloric acid, separating supernate after ultrasonic oscillation and centrifugation, dripping the supernate on a glass substrate coated with a nanoparticle layer on the surface, drying to form samples to be detected, optimizing experimental parameters of LIBS detection, and carrying out spectrum acquisition and analysis on the samples to be detected.
Preferably, the acidity of the hydrochloric acid is pH 1 and the mass ratio of the sample to the hydrochloric acid is 1: 5.
Preferably, in order to effectively extract heavy metal elements in the sample, the ultrasonic oscillation time is set to be 30min, the rotation speed of the centrifugal machine is set to be 10000r/min, and the centrifugation time is set to be 30 min.
Preferably, the substrate is a frosted glass material, and a frosted glass slide can be selected.
Preferably, the nanogold standard solution (with the diameter of the nanoparticles being about 13nm and the concentration being 0.05mg/mL) is dripped on the substrate and is fully paved, and then the substrate is placed on a hot plate at 50 ℃ to evaporate the nanogold solution to dryness, so that the nanogold particle layer is obtained. Or dripping the nano-silver standard solution on a substrate, fully spreading the substrate, and then placing the substrate on an electric hot plate at 50 ℃ to evaporate the nano-silver solution to dryness to obtain a nano-silver particle layer.
Further, experimental parameters including laser energy, diameter of a focusing spot, laser energy density, spectrum acquisition delay and gate width are optimized, preferably, 50mJ of laser energy is adopted, 270 mu m of diameter of the focusing spot is adopted, and the laser energy density is 87J/cm2The spectrum acquisition delay is 1000ns, and the gate width is 5000 ns.
Further, the method comprises the steps of carrying out spectrum collection analysis on a sample to be detected, adding heavy metal standard solutions with different concentrations into the sample to be detected, preparing samples with series concentrations, carrying out spectrum collection, establishing a calibration curve by utilizing the correlation between the concentration of the heavy metal and the spectral intensity, substituting the spectral intensity of the sample to be detected with unknown concentration into the calibration curve, and obtaining the content of the heavy metal in the sample to be detected with unknown concentration.
Compared with the prior art, the invention has the following beneficial effects:
(1) the LIBS detection of fresh aquatic products is converted into the detection of a deposition sample on a substrate through the solid-liquid-solid state conversion.
(2) By adopting a substrate-assisted nano particle-combined enhancement method, LIBS signal enhancement for heavy metal detection of aquatic products is realized under a common LIBS experimental system, and the detection sensitivity is improved.
Description of the drawings:
FIG. 1 shows LIBS spectra near Cd I228.802nm for different sample preparation methods in example 1.
FIG. 2 is a characteristic spectrum of LIBS at about Pb I405.781 nm for different sample preparation methods in example 1.
FIG. 3 is a single variable calibration plot of the Cd I228.802nm peak intensity for different sample preparation methods in example 1.
FIG. 4 is a univariate plot of the peak intensity of Pb I405.781 nm for the different sample preparation methods of example 1.
The specific implementation mode is as follows:
the invention is further illustrated by the following specific examples in combination with the accompanying drawings.
Example 1
A signal enhancement method for detecting heavy metals in aquatic products based on an LIBS technology specifically comprises the following steps:
1. sample preparation
(1) Firstly, homogenizing fresh cod fish meat, adding Cd and Pb standard solutions (shown in table 1) with different concentrations, oscillating for 2h to fully absorb the Cd and Pb standard solutions, adding a hydrochloric acid solution with pH of 1 to 1 according to the ratio of a sample to hydrochloric acid of 1:5, then ultrasonically oscillating for 30min, then centrifuging for 30min in a centrifuge with the rotation speed of 10000r/min, and taking out supernatant for later use.
Table 1 addition concentration of heavy metal elements in fresh cod sample
(2) The slides were cut to 25X 25mm using a frosted glass slide as the auxiliary substrate for signal enhancement.
(3) And (3) taking out the cut square glass slide, dripping 400 mu L of nano-gold standard solution (the diameter of the nano-particles is about 13nm, and the concentration is 0.05mg/mL) on the glass slide, fully spreading the glass slide, placing the glass slide on an electric hot plate at 50 ℃ to evaporate the nano-gold solution, dripping 600 mu L of the supernatant sample obtained in the step (1) until the sample solution is evaporated to dryness, and preparing a glass substrate combined nano-gold sample. The liquid is wary of spilling or spilling over the slide during this process.
For comparison, 600. mu.L of the supernatant sample obtained in step (1) was directly dropped onto a glass slide, and the glass slide was placed on a 50 ℃ hot plate to evaporate the supernatant, thereby preparing a glass substrate control sample (substrate auxiliary sample).
And further comparing, namely drying the cod meat pulp added with heavy metals with different concentrations, adding the adhesive, uniformly mixing, tabletting, and preparing a directly-tabletted comparison sample (tabletting sample).
2. Optimizing experimental conditions and performing LIBS spectral detection
And (3) investigating the characteristic spectral lines of Cd and Pb elements commonly used in an NIST database and related documents, and selecting Cd I228.802nm and Pb I405.781 nm for analysis. Optimizing experimental conditions and obtaining optimal detection parameters, wherein the experimental conditions are specifically adopted as follows: the laser energy is 50mJ, the spot diameter is 270 mu m, and the laser energy density is 87J/cm2The pulse laser frequency is 2Hz, the spectrum acquisition delay is 1000ns, and the gate width is 5000 ns. And (3) carrying out spectrum detection on the sample under the optimal experimental condition, collecting a characteristic spectrum every time 50 laser pulses are accumulated, and repeatedly collecting 5 spectrums for each sample to obtain the LIBS spectrum data of Cd and Pb elements under different concentrations.
3. Analysis of spectrum intensity enhancement effect of Cd and Pb elements
The raw spectral data was pre-processed and the spectral background was subtracted by baseline correction to compare the spectral intensity enhancement effect of different sample preparation methods, as shown in fig. 1 and 2. For Cd and Pd elements, effective spectral signals can hardly be acquired by a sample subjected to tabletting treatment, the spectral intensity of the sample assisted by the substrate is slightly enhanced compared with that of a tabletted sample, and after a nanogold particle layer is deposited on the substrate, the spectral intensity is improved by one to two orders of magnitude, so that the enhancement effect is very remarkable.
The spectral intensities for the different sample preparation methods were compared as shown in table 2. Compared with a tabletting sample, the spectral intensity of Cd and Pd elements of the substrate auxiliary sample is respectively improved by 2.73 and 2.03 times, and the spectral intensity is further respectively improved by 88.72 and 15.51 times after the nano-gold particle layer is added. Compared with a method of singly adopting a substrate for assistance, the method of combining the substrate for assistance and the nano-gold particles has the advantage that the spectral intensities of Cd and Pd elements are respectively improved by 32.47 times and 7.65 times. The result shows that compared with the traditional tabletting method, the substrate-assisted method can improve the LIBS spectral signal intensity, and on the basis, the combination of the nano-gold particles can continue to obviously enhance the spectral signal intensity.
TABLE 2 LIBS spectral signal intensity enhancement effect of different sample preparation methods
4. Univariate calibration curve of Cd, Pb element
Quantitative analysis is carried out on the two heavy metal elements by adopting a univariate calibration method, characteristic spectral lines of Cd I228.802nm and PbI 405.781nm are selected, and a calibration curve is established, as shown in figures 3 and 4. As can be seen from the figure, the spectral intensity and the element concentration of Cd and Pb in the sample combined with the nanogold by the glass substrate show good linear relationship, the slope of the calibration curve is obviously higher than that of other two comparative samples (a tabletting sample and a pure glass substrate sample), the fitting coefficient of the calibration curve is more than 0.98, and the linear fitting degree is higher.
According to the univariate calibration curve, the detection limits of Cd and Pb elements of different preparation methods are calculated, and the results are collated and summarized as shown in Table 3. It can be seen that the detection limit of the tabletted sample is the highest, the sample with substrate assistance is the second time, the sample with substrate assistance combined with nanoparticles is the lowest, and the detection limits of Cd and Pb elements are respectively reduced to 0.076mg/kg and 0.128mg/kg, which shows that the sensitivity of LIBS detection is significantly improved. According to the national standard GB2762-2017[ S ] for food safety, the limit of pollutants in food is 0.1mg/kg and 0.5mg/kg respectively for Cd and Pb elements in edible fish, the limit standard can be reached by adopting a detection method of substrate assistance combined with nano-gold particle enhancement, a sample which is only subjected to substrate assistance can only meet the Pb element detection, and the detection requirements cannot be reached by a traditional tabletting method.
TABLE 3 comparison of the quantitative determination results of Cd and Pb elements in different sample preparation methods
Claims (7)
1. A signal enhancement method for heavy metal detection in aquatic products based on an LIBS technology is characterized in that a substrate is adopted to assist and combine a nanoparticle enhancement mode, fresh aquatic products are homogenized, heavy metal elements in samples are extracted by hydrochloric acid, supernate is separated after ultrasonic oscillation and centrifugation, the supernate is dripped on a glass substrate with the surface covered with a nanoparticle layer and is dried to form samples to be detected, experimental parameters of LIBS detection are optimized, and spectrum collection and analysis are carried out on the samples to be detected.
2. The signal enhancement method for detecting the heavy metals in the aquatic products based on the LIBS technology as claimed in claim 1, wherein the acidity of hydrochloric acid used for extracting the homogenate sample is pH 1, and the mass ratio of the sample to the hydrochloric acid is 1: 5.
3. The signal enhancement method for detecting the heavy metals in the aquatic products based on the LIBS technology as claimed in claim 1, wherein the extraction process is ultrasonic oscillation for 30min, and then centrifugation for 30min in a centrifuge with a rotation speed of 10000 r/min.
4. The LIBS technology-based signal enhancement method for detecting heavy metals in aquatic products according to claim 1, wherein the adopted substrate is ground glass.
5. The LIBS technology-based signal enhancement method for detecting heavy metals in aquatic products according to claim 1, wherein the nanoparticle layer coated on the substrate is obtained by dripping a nanogold standard solution or a nanosilver standard solution on the substrate and drying the nanogold standard solution or the nanosilver standard solution.
6. The LIBS technology-based signal enhancement method for detecting heavy metals in aquatic products according to claim 1, wherein the optimized LIBS detection experiment parameters are as follows: laserThe energy is 50mJ, the diameter of a focusing spot is 270 mu m, and the laser energy density is 87J/cm2The spectrum acquisition delay is 1000ns, and the gate width is 5000 ns.
7. The LIBS technology-based signal enhancement method for detecting heavy metals in aquatic products according to claim 1, wherein the samples to be detected are subjected to spectrum collection and analysis, and the method is characterized in that heavy metal standard solutions with different concentrations are added into the samples to be detected, samples with a series of concentrations are prepared, a calibration curve is established by utilizing the correlation between the concentration of the heavy metals and the spectral intensity after spectrum collection, and the content of the heavy metals in the samples to be detected with unknown concentrations can be obtained by substituting the spectral intensity of the samples to be detected with unknown concentrations into the calibration curve.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010370930.1A CN111551538A (en) | 2020-05-06 | 2020-05-06 | LIBS technology-based signal enhancement method for heavy metal detection in aquatic products |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010370930.1A CN111551538A (en) | 2020-05-06 | 2020-05-06 | LIBS technology-based signal enhancement method for heavy metal detection in aquatic products |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111551538A true CN111551538A (en) | 2020-08-18 |
Family
ID=72001800
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010370930.1A Pending CN111551538A (en) | 2020-05-06 | 2020-05-06 | LIBS technology-based signal enhancement method for heavy metal detection in aquatic products |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111551538A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112557494A (en) * | 2020-11-05 | 2021-03-26 | 广州海关技术中心 | Pollack species identification method based on multiple elements and chemometrics |
| CN117805085A (en) * | 2024-02-29 | 2024-04-02 | 北京市农林科学院智能装备技术研究中心 | Method for measuring concentration of trace heavy metal ions in liquid |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105954260A (en) * | 2016-06-07 | 2016-09-21 | 华中科技大学 | Sample preparation method for quantitative analysis of water elements based on laser induced breakdown spectrum |
| CN108519368A (en) * | 2018-04-08 | 2018-09-11 | 华中科技大学 | A kind of detection method and its detection device of soil available heavy metal element |
| CN109187493A (en) * | 2018-11-13 | 2019-01-11 | 北京理工大学 | It is divided the femtosecond laser processing monitoring method and device of the confocal Raman-LIBS spectrographic detection of pupil |
| CN106770195B (en) * | 2017-01-24 | 2019-11-29 | 浙江大学 | Blade heavy metal content detection method based on CN element ratios correction moisture content |
-
2020
- 2020-05-06 CN CN202010370930.1A patent/CN111551538A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105954260A (en) * | 2016-06-07 | 2016-09-21 | 华中科技大学 | Sample preparation method for quantitative analysis of water elements based on laser induced breakdown spectrum |
| CN106770195B (en) * | 2017-01-24 | 2019-11-29 | 浙江大学 | Blade heavy metal content detection method based on CN element ratios correction moisture content |
| CN108519368A (en) * | 2018-04-08 | 2018-09-11 | 华中科技大学 | A kind of detection method and its detection device of soil available heavy metal element |
| CN109187493A (en) * | 2018-11-13 | 2019-01-11 | 北京理工大学 | It is divided the femtosecond laser processing monitoring method and device of the confocal Raman-LIBS spectrographic detection of pupil |
Non-Patent Citations (4)
| Title |
|---|
| NANOPARTICLE ENHANCED LASER-INDUCED BREAKDOWN SPECTROSCOPY FOR M: "Nanoparticle Enhanced Laser-Induced Breakdown Spectroscopy for Microdrop Analysis at subppm Level", 《ANALYTICAL CHEMISTRY》 * |
| PING YANG ET AL.: "High-sensitivity determination of cadmium and lead in rice using laser-induced breakdown spectroscopy", 《FOOD CHEMISTRY》 * |
| 汪慧 等: "稀酸浸提水产品中重金属铜、铅和镉", 《食品科学》 * |
| 郭珍珠 等: "共识模型用于激光诱导击穿光谱检测泥蚶重金属铜的含量", 《光子学报》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112557494A (en) * | 2020-11-05 | 2021-03-26 | 广州海关技术中心 | Pollack species identification method based on multiple elements and chemometrics |
| CN117805085A (en) * | 2024-02-29 | 2024-04-02 | 北京市农林科学院智能装备技术研究中心 | Method for measuring concentration of trace heavy metal ions in liquid |
| CN117805085B (en) * | 2024-02-29 | 2024-06-07 | 北京市农林科学院智能装备技术研究中心 | Method for measuring concentration of trace heavy metal ions in liquid |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Grotti et al. | Temporal distribution of trace metals in Antarctic coastal waters | |
| Oroian et al. | Multi-element composition of honey as a suitable tool for its authenticity analysis | |
| Jackson et al. | Evidence for mass-independent and mass-dependent fractionation of the stable isotopes of mercury by natural processes in aquatic ecosystems | |
| Maher et al. | Arsenic distribution and species in two Zostera capricorni seagrass ecosystems, New South Wales, Australia | |
| Stankovska et al. | Monitoring of trace elements in honey from the Republic of Macedonia by atomic absorption spectrometry | |
| Windom et al. | Trace metal transport in a tropical estuary | |
| dos Santos Silva et al. | Dispersive liquid-liquid microextraction for simultaneous determination of cadmium, cobalt, lead and nickel in water samples by inductively coupled plasma optical emission spectrometry | |
| CN109738507B (en) | Micro-plastic detection device and method based on pyrolysis-mass spectrometry technology | |
| Chen et al. | Comparison between pure-water-and seawater-soluble nutrient concentrations of aerosols from the Gulf of Aqaba | |
| CN111551538A (en) | LIBS technology-based signal enhancement method for heavy metal detection in aquatic products | |
| Reynaud et al. | Effect of feeding on the carbon and oxygen isotopic composition in the tissues and skeleton of the zooxanthellate coral Stylophora pistillata | |
| Guédron et al. | Tidal cycling of mercury and methylmercury between sediments and water column in the Venice Lagoon (Italy) | |
| Guo et al. | New insights into the source of decadal increase in chemical oxygen demand associated with dissolved organic carbon in Dianchi Lake | |
| Sudheesh et al. | Effects of seasonal anoxia on the distribution of phosphorus fractions in the surface sediments of southeastern Arabian Sea shelf | |
| Karnan et al. | Discriminating the biophysical impacts of coastal upwelling and mud banks along the southwest coast of India | |
| Uluozlu et al. | 3-Ethyl-4-(p-chlorobenzylidenamino-4, 5-dihydro-1H-1, 2, 4-triazol-5-one (EPHBAT) as precipitant for carrier element free coprecipitation and speciation of chromium (III) and chromium (VI) | |
| CN102519930A (en) | Method for rapidly determining selenium content in plant sample | |
| Chifflet et al. | Isotopic compositions of copper and zinc in plankton from the Mediterranean Sea (MERITE-HIPPOCAMPE campaign): tracing trophic transfer and geogenic inputs | |
| Volzhenin et al. | Direct Determination of cadmium, lead, and zinc in mussels by two-stage probe atomization (TPA) graphite furnace atomic absorption spectrometry (GFAAS) | |
| Taran et al. | Relations between the chemical composition of organic matter in lacustrine ecosystems and the genesis of their sapropel | |
| Frache et al. | Effects of ice melting on Cu, Cd and Pb profiles in Ross Sea waters (Antarctica) | |
| Kravchishina et al. | Grain-size composition of the suspended particulate matter in the marginal filter of the Severnaya Dvina River | |
| 石井紀明 et al. | Determination and distribution of trace elements in marine invertebrates. | |
| Miao et al. | Macronutrient and iron limitation of phytoplankton growth in Hong Kong coastal waters | |
| Demina et al. | Spatial distribution of microelements in the seston of the White Sea |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20200818 |
|
| RJ01 | Rejection of invention patent application after publication |