Some standard content:
GB17378.5—1998
This standard is the fifth part of the Marine Monitoring Specifications, which is revised on the basis of the HY003.5—91 industry standard. This standard specifies the requirements and analysis methods for sediment analysis. The Marine Monitoring Specifications include the following parts: GB17378.1-1998 Marine Monitoring Specifications
GB17378.2-1998 Marine Monitoring Specifications
GB17378.3-1998 Marine Monitoring Specifications
Part 1: General
Part 2: Data processing and analysis quality control Part 3: Sample collection, storage and transportation GB17378.4--1998 Marine Monitoring Specifications
Part 4: Seawater analysis
GB17378.5-1998 Marine Monitoring Specifications
Part 5: Sediment analysis
GB17378.6-1998 Marine Monitoring Specifications
Part 6: Organism analysis
GB17378.7-1998 Marine Monitoring Specifications Part 7: Ecological investigation and biological monitoring of offshore pollution Appendix A to this standard It is a prompt appendix. This standard is proposed by the State Oceanic Administration.
This standard is under the jurisdiction of the National Center for Marine Standards and Metrology. This standard was drafted by the Second Institute of Oceanography of the State Oceanic Administration. The main drafters of this standard are: Chen Weiyue, Zhang Chunming, Xu Kuncan, Wang Huichang, Chen Banglong, Gu Guoliang. 559
1 Scope
National Standard of the People's Republic of China
Specification for marine monitoringPart 5; Sediment analysis
GB 17378.5—1998
This standard specifies 16 marine sediment measurement items and 34 analysis methods, and puts forward technical requirements for sample collection, storage, transportation, pretreatment, measurement results and calculation.
This standard applies to the investigation and monitoring of sediments in oceans, offshore, estuaries and harbors, and also to the investigation and monitoring of dredged and dumped materials in offshore, harbors and estuaries.
2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T13909--92 Marine Survey Specification Marine Geological and Geophysical Survey GB17378.2-1998 Marine Monitoring Specification Part 2: Data Processing and Analysis Quality Control GB17378.3-1998 Marine Monitoring Specification Part 3: Sample Collection, Storage and Transportation Part 4: Seawater Analysis
Marine Monitoring Specification
GB 17378.4-1998
3 Definitions
This standard adopts the following definitions.
3.1 Sample pretreatmentsample pretreatment The sample processing process from the time the sample is collected on the deck until it is sent to the laboratory for analysis and determination. 3.2 Sample pre-processingsamplepre-processing In sample analysis, the processing process from sample weighing to before determination. 3.3 Total transfer
The process of transferring all the substances in a container to another container. 3.4 Sample digesting solutionThe solution to be determined (if there is residue, it refers to the upper clear liquid) prepared after the sample is pre-treated. 3.5 Sample determination subsampleWhen a part of the sample digestion solution is measured for determination, this part of the sample digestion solution is called the sample determination subsample. 3.6 Standard line
Refers to the scale line for measuring the volume of the container.
3.7 Evaporating to fumeless refers to the container after the solvent evaporates, and when it is placed at room temperature, there is still no white smoke coming out. Approved by the State Administration of Quality and Technical Supervision on June 22, 1998 560
Implementation on January 1, 1999
3.8 Ordinary temperature refers to 20℃.
3.9 Room temperature
refers to 0℃～30℃.
3.10 Dry sediment
Sediment sample dried at 105℃±1℃. 4 General provisions
GB 17378.51998
4.1 Collection, pretreatment, preparation and storage of analytical samples 4.1.1 Collection of analytical samples
(For sample collection and on-site description, see 4.1 and 4.2 of GB17378.3-1998). 4.1.1.1 Equipment and tools
一 Sample tray or sample board: made of hardwood or polyethylene board; sample box, sample bottle (125, 500mL ground wide-mouth bottle) and polyethylene bag; plastic knife, spoon;
Beaker: 50, 100mL;
一 Others: record form, plastic label card, pencil, marker, steel tape measure, rubber band, work diary, etc. 4.1.1.2 Collection of analytical samples
4.1.1.2.1 Collection of surface sediment analysis samples Use a plastic knife or spoon to carefully take the upper 0~~1cm and 1~2cm sediments from the ear cover of the mud sampler, representing the surface layer and subsurface layer respectively. If a gravel layer is encountered, mixed sampling can be performed in the 0~3cm layer. ～ In general, 3~4 analytical samples are taken from each layer, and the sampling volume depends on the analysis project. If the sampling volume is insufficient at one time, it should be collected again. 1) Take the sediment sample just collected and quickly put it into a 100mL beaker (about half a cup, try to keep the sample in its original state and avoid air from entering) for on-site determination of redox potential (it can also be directly measured in the mud sampler). 2) Take about 5g of fresh wet sample and put it in a 50mL beaker for on-site determination of sulfide (ion selective electrode method). If the sulfide is determined by colorimetry or iodine titration, take 20-30g of fresh wet sample and put it in a 125mL ground-mouth wide-mouth bottle, fill it with nitrogen and plug it tightly with a ground-mouth stopper. 3) Take 500-600g of wet sample and put it in a clean polyethylene bag and tie the bag tightly. For the determination of copper, lead, cadmium, zinc, chromium, arsenic and selenium. 4) Take 500-600g of wet sample and put it in a 500mL ground-mouth wide-mouth bottle and seal the bottle mouth. For the determination of moisture content, particle size, total mercury, oil, organic carbon, organochlorine pesticides and polychlorinated biphenyls. 4.1.1.2.2 Sampling of columnar sediment analysis The upper 30cm of the sample column is cut into small sections with a plastic knife at intervals of 5cm and the lower 30cm (determined when the length exceeds 1m). Carefully scrape the surface of the sample column and cut it into three parts along the longitudinal direction (the ratio of the three parts is 1:1:2). The two smaller parts are placed in a 50mL beaker (when the sulfide is determined by the ion selective electrode method, if the sulfide is determined by the colorimetric method or the iodine method, it is placed in a 125mL ground-mouth wide-mouth bottle, filled with nitrogen, and sealed for storage) and a polyethylene bag, and the other part is placed in a 125mL ground-mouth wide-mouth bottle. 4.1.2 Sample pretreatment
4.1.2.1 Sample registration
4.1.2.1.1 The sample bottle and polyethylene bag are pre-soaked in (1+3) nitric acid for 2-3 days, rinsed with deionized water, and dried. After bottling, hang the sample label card (Figure 1), and write the sea area station number, layer and sampling date on the label card with a marker. 4.1.2.1.2 Put the sample into a polyethylene bag, and put the label card with the station number and layer filled in into the outer bag, and tighten the bag with a rubber band. Pack and store in a cool place.
GB 17378. 5—1998
Year, month, day
Figure 1 Sediment sample plastic label card
4.1.2.1.3 For all samples, fill in the sampling sea area, station number, layer, quantity and site description in Table 18. 4.1.2.2 On-site storage of samples
Samples that need to be brought back to the land laboratory should be stored in a cool place, preferably in a refrigerator or cold storage, and stored at around 4°C. 4.1.2.3 Transportation of samples
Samples should be delivered to land laboratories in a timely manner. When delivering samples, a sample delivery form (see Table 19) should be filled in triplicate. One copy should be kept for record, and two copies should be delivered to the receiving unit along with the samples.
4.1.3 Preparation of analytical samples
4.1.3.1 Preparation of analytical samples for determination of copper, lead, zinc, chromium, arsenic and selenium. 4.1.3.1.1. Transfer the wet sample in the polyethylene bag to a clean and numbered porcelain evaporator, place it in an oven at 80-100℃, exhaust and dry (use a glass rod to frequently turn the sample and crush the large pieces to accelerate drying). Spread the dried sample on a clean polyethylene plate, crush the sample with a polyethylene rod, and remove gravel and large animal and plant debris. Put the sample into an agate bowl (about 100g of dry sample per 500mL agate bowl). Put in an agate ball and grind it on a ball mill until all pass through 160 mesh (the number of large and small agate balls and the grinding time and other conditions are determined by experiments in advance, and no more sieving is required after grinding). It can also be crushed manually with an agate mortar, and sieved with a 160-mesh nylon sieve and covered with a plastic cover to prevent the sample from escaping. Mix the processed sample thoroughly. 4.1.3.1.2 Quartering method Take 10-20g of the prepared sample, put it into a sample bag (the station number, level, etc. of the sample have been filled in), and send it to each laboratory for analysis and determination. The remaining samples are placed in 250mL ground-mouth wide-mouth bottles (or 200mL wide-mouth plastic bottles with sealed inner lids), the bottle caps are tightly closed, and they are kept as duplicate samples.
4.1.3.2 Preparation of analytical samples for determination of oils, organic carbon, organochlorine pesticides and polychlorinated biphenyls: 4.1.3.2.1 Spread the samples after the moisture content, particle size and total mercury have been determined on a clean and numbered sugar porcelain plate, and place it in a cool and ventilated place indoors. Turn the samples from time to time and crush the large pieces to accelerate drying, so as to prepare air-dried samples. 4.1.3.2.2 Spread the air-dried samples on a polyethylene plate, crush the samples with a polyethylene rod, and remove gravel and large particles of animal and plant debris.
4.1.3.2.3 Grind in a ball mill until all pass through 80 mesh (pre-tested for conditions, no more sieving after grinding), or grind manually with a porcelain mortar, and sieve with an 80 mesh metal sieve covered with a metal cover. Prevent sample escape. Mix the processed sample thoroughly. 4.1.3.2.4 Quartering method Take 40-50g of the prepared sample, put it into a sample bag (with the station number, level, etc. of the sample filled in), and send it to each laboratory for analysis and determination.
Note:
The operator must wear a mask and operate under well-ventilated conditions. The tools and instruments for sample crushing and sampling must be purified first to avoid contamination of the sample.
4.1.4 Preservation of analytical duplicate samples
4.1.4.1 The significance and purpose of preserving analytical duplicate samples Analytical samples are hard to come by. In order to ensure the quality of the test results and the comparability of the data of each survey and monitoring cruise, and to accumulate data for the development of marine environmental protection science, analytical duplicate samples should be properly preserved for analytical quality inspection and other purposes. 4.1.4.2 Preservation method of analytical duplicate samples
The preservation method of duplicate samples shall be handled in accordance with the relevant regulations of the competent business department. 562
4.2 Unified regulations and requirements
GB17378.51998
4.2.1 Drying of analytical samples: When the drying temperature and time are not specified, it refers to 105±1℃, drying for 2h. 4.2.2 In the preparation of standard solutions, the pipettes used should be calibrated in advance. The volumetric bottles should be of first-class quality. 4.2.3 Data processing shall be carried out in accordance with the requirements of GB17378.2. 4.2.4 Unless otherwise specified in the text, pH values may be measured with precision or wide pH test paper. 4.2.5 To check the quality of the analysis results, the competent business department shall randomly select inspection samples from a batch of basic samples according to Table 1, pack them in bags and assign sample numbers, and hand over the basic samples and inspection samples to relevant personnel for measurement. Table 1 Proportion of inspection samples selected from analytical samples Number of analytical samples
Percentage of inspection samples
4.2.5.1 The test items of the inspection samples are the same as those of the basic samples. 10
10～30
4.2.5.2 When the number of samples is large, the basic samples and inspection samples should not be arranged in the same batch for testing. >30
4.2.5.3 The test results shall be summarized by the competent business department, and the analysis quality shall be controlled according to the relative deviation tolerance of the two samples listed in Table 2. When the deviation rate of the two sample inspection results of a certain measurement item is greater than 30%, all the measurement items in this batch of basic samples shall be re-weighed for measurement. If the above-mentioned deviation still occurs, the competent department of the business should carefully check and analyze the reasons with the analysts (such as the preparation of standard solution, environmental quality, whether the instruments and equipment used are abnormal, etc.), and then conduct the determination of this batch of samples (basic samples and inspection samples). When the deviation rate of the double sample inspection results of a certain measurement item is less than 30%, the samples that exceed the deviation need to be re-weighed and measured until the measured results are qualified. When reporting data, it is calculated according to the mean of the parallel double sample results.
Table 2 Relative deviation table of parallel double samples
Order level of analysis results
Relative deviation tolerance limit (%)
4.2.5.4 The determination of water content and redox potential of sediments shall be carried out in accordance with the provisions of this specification. The determination of sulfide in sediments does not require double sample inspection.
4.2.6 The competent department of the business shall insert 2 to 3 marine sediment component analysis standard substances (packed separately and assigned sample numbers) into each batch of samples analyzed (about 20) to check whether there is any systematic error. 4.3 Explanation
4.3.1 The density (p) of various acids and bases refers to the number of grams per milliliter at 20°C. 4.3.2 Except for the items measured on-site on board, which list the instruments and equipment used, the items measured in land laboratories only list the main instruments and special equipment and blood, etc.
4.3.3 When the desiccant is not specified, it refers to color-changing silica gel. 4.3.4 The concentration of the prepared standard solution of the element refers to the concentration of the element. 4.3.5 Solutions without specified solvents are all aqueous solutions. 4.3.6 In addition to the electrochemical analysis method, the linear regression equation of the calibration curve can also be used to calculate the mass or concentration of the analyte, and then the content of the analyte in the sample can be calculated according to the calculation formula. (When a point in the middle of the calibration curve is abnormally large, the use of the linear regression equation to calculate the content will cause a large error. In this case, the point should be discarded and the result should be obtained by the graphical method. If the abnormal point appears at both ends of the calibration curve, the range of the calibration curve will be correspondingly reduced. At this time, the calibration curve should be redrawn. 4.3.7 The determination of particle size in sediments shall be carried out in accordance with Chapter 14 of GB/T13909-92. 563
Determination items, methods and detection limits
National code
GB 17378. 5—1998
Table 3 Determination items, methods and detection limits
Items and analytical methods
Cold atomic absorption spectrophotometry
Dithiol spectrophotometry
Flameless atomic absorption spectrophotometry
Flame atomic absorption spectrophotometry
Sodium diethyldithiocarbamate spectrophotometry Lead
Flameless atomic absorption spectrophotometry method
flame atomic absorption spectrophotometry
dithiol spectrophotometry
no flame atomic absorption spectrophotometry
flame atomic absorption spectrophotometry
dithiol spectrophotometry
flame atomic absorption spectrophotometry
dithiol spectrophotometry
diphenylcarbazide spectrophotometry
no flame atomic absorption Spectrophotometry
Arsenic acid-crystal violet spectrophotometry
Hydride-atomic absorption spectrophotometry
Catalytic polarography
Fluorescence spectrophotometry
3.3'-Diaminobenzidine tetrahydrochloride spectrophotometryCatalytic polarography
Fluorescence spectrophotometry
Gravimetric method
Ultraviolet spectrophotometry
666, DDT
Gas chromatography
PCB
Gas chromatography
Detection limit (W)
5×10~9
30×10-9
2×10-6
1×10-6
1×10-6
3×10-6
0.5×10-6
0. 04 -6
0. 1X10-6
0.5×10-6
0. 03×10-6
2×10-6
3×106
α-666,3pg
-666,4pg
-666,3pg
8-666.5pg
Pp*-DDE,4 pg||tt| |op'-DDT,11 pg
pp'-DDD,6 pg
pp'-DDT,18 pg
Catalog number
6Total mercury
6.1 Cold atomic absorption spectrophotometry
6.1.1 Scope and application fields
GB 17378. 5—1998
Table 3 (end)
Items and analytical methods
Dieldrin
Gas chromatography
Sulfide
Methylene blue spectrophotometry
Ion selective electrode method
Iodine titration
Organic carbon
Potassium dichromate oxidation-reduction capacity method
Thermal conductivity method
Water content
Gravimetric method
Redox potential
Potentiometer method
This method is applicable to the determination of total mercury in estuary, nearshore and ocean sediments. Detection limit (W): 5×10-9.
6.1.2 Principle of the method
Detection limit (W)
0.3×10-6
0.2×10-6
4×10-6
3×10-2
Can be measured on site
On site measurement
The sample is heated and digested with nitric acid-hydrogen peroxide, and the ionic mercury is reduced by stannous chloride and converted into mercury vapor, which enters the absorption cell with the carrier gas. The characteristic absorption value at a wavelength of 253.7nm is proportional to the mercury content. 6.1.3 Reagents and their preparation
Unless otherwise specified, the reagents used are analytically pure, and the water is mercury-free distilled water or equivalent pure water. 6.1.3.1 Mercury standard solution
6.1.3.1.1 Mercury standard stock solution: 1.000mg/mL Weigh 0.1353g mercuric chloride (HgCl2, high-grade pure, placed in a sulfuric acid dryer for more than 24h) in a 50mL beaker, dissolve it with nitric acid solution (6.1.3.7), transfer the entire amount to a 100mL volumetric flask, add nitric acid solution (6.1.3.7) to the mark, and mix. 6.1.3.1.2 Mercury standard intermediate solution: 10.0ug/mL Weigh 1.00mL mercury standard stock solution (6.1.3.1.1) in a 100mL volumetric flask, add nitric acid solution (6.1.3.7) to the mark, and mix.
6.1.3.1.3 Mercury standard solution: 1.00μg/mL Take 5.00mL of mercury standard intermediate solution (6.1.3.1.2) in a 50mL volumetric flask, add 0.5mol/L sulfuric acid solution (6.1.3.9) to the mark, mix well (prepare before use).
6.1.3.2 Stannous chloride solution: 100g/L
Weigh 20g of stannous chloride (SnCl22Hz0) in a 250mL beaker, add 100mL of hydrochloric acid solution (6.1.3.8) and 80mL of water, heat until the stannous chloride is completely dissolved, add water to 200mL, mix well, and transfer to a 250mL reagent bottle. 6.1.3.3 Hydroxylamine hydrochloride solution: 100g/L
Weigh 25g of hydroxylamine hydrochloride (NH,OH·HCl) and dissolve it in water and dilute it to 250mL, then transfer it to a 500mL reagent bottle. 6.1.3.4 Potassium permanganate solution: 50g/L
Weigh 10g of potassium permanganate (KMnO,) in a 250mL beaker, add 200mL of water, heat to dissolve, and transfer it to a brown reagent bottle after cooling.
6.1.3.5 Hydrogen peroxide solution: 30%, premium grade. GB 17378. 5—1998
6.1.3.6 Nitric acid (HNO.): p=1.42g/mL, premium grade. 6.1.3.7 Nitric acid solution: 1+19
Mix 1 volume of nitric acid (6.1.3.6) with 19 volumes of water. 6.1.3.8 Hydrochloric acid solution: 1+1
Mix equal volumes of hydrochloric acid (HCl, p=1.19 g/mL, high purity) and water. 6.1.3.9 Sulfuric acid solution: 0.5 mol/L
Slowly add 28 mL of concentrated sulfuric acid to 972 mL of water and mix well. 6.1.4 Instruments and equipment
Cold atomic absorption mercury analyzer;
Vacuum pump,
Voltastat;
Recorder;bzxz.net
Water bath;
-Rotameter,
-Micropipette: 10, 20, 50, 100uL; One reaction bottle: 250mL (ground mouth);
General laboratory instruments and equipment
1-Vacuum pump; 2-Air flow regulating valve; 3-Mercury waste gas absorber; 4-Mercury analyzer; 5-Light absorption cell; 6-Drying tube; 7-Three-way valve; 8-Mercury vapor Generator bottle; 9-air purification device; 10-activated carbon absorber; 11-gas flow meter Figure 2 Cold atomic absorption mercury measuring device
6.1.5 Analysis steps
6.1.5.1 Draw a standard curve:
Add 50mL of water to a 250mL ground mouth reaction bottle, add 20, 40, 60, 80, 100uL of mercury standard solution (6.1.3.1.3) respectively, and add 2mL of stannous chloride solution (6.1.3.2) in sequence, quickly cover the bottle stopper, cut off the gas line according to Figure 2, shake for 2 minutes, connect the gas line to measure the absorbance value (A). Use the same method to measure the standard blank absorbance value (A.). And record the data in Appendix Table A1 of GB17378.4-1998. On centimeter square paper, draw a standard curve of mercury with (A, -A.) as the ordinate and the number of nanograms of mercury as the abscissa. Paste the standard curve in the standard curve column in Table A1 of Appendix GB17378.4-1998. 6.1.5.2 Sample digestion
6.1.5.2.1 Weigh about 1g of wet sediment sample (±0.001g), put it in a 50mL beaker, add 5mL of nitric acid (6.1.3.6), and digest it in a 90±5℃ water bath for 30min. At the same time, make an analytical blank. 6.1.5.2.2 Take out, cool, and add 1mL of hydrogen peroxide (6.1.3.5) dropwise, and continue to digest in a water bath for 30min. After cooling, transfer the entire amount to a 100mL volumetric flask.
6.1.5.2.3 Add potassium permanganate solution (6.1.3.4) dropwise until the red color does not fade. 6.1.5.2.4 Add 2mL of hydroxylamine hydrochloride solution (6.1.3.3) to make the red color fade away and add water to the mark, mix well and wait for testing. 6.1.5.3 Determination of samples
Pipette a fixed volume (V2) of sample digestion solution into the reaction bottle, add water to make up to 50mL, add 2mL of stannous chloride solution 566
GB 17378. 51998
(6.1.3.2), quickly cover the bottle stopper, cut off the gas line, and shake for 2 minutes. Connect the gas line and measure the absorbance value (A.) and the analytical blank absorbance value (Ab). Use the (A.Ab) value to find the corresponding nanograms of mercury from the standard curve. 6.1.6 Record and Calculation
Record the measured absorbance value in Table A2 of Appendix of GB17378.4--1998, and calculate the total mercury content in the dry sediment sample according to the following formula. mV
WHe - V,M(1 -WH,o)
WHg——the total mercury content in the dry sediment sample, mass ratio, 10-°; m the amount of mercury obtained from the standard curve, ng; V the volume of the sample digestion solution, mL;
Vz the volume of the sample subsample for determination, mL
M-—the amount of sample weighed, g;
WH,—the moisture content of the wet sample, %.
6.1.7 Precision and accuracy
6.1.7.1 Repeatability
Five laboratories analyzed the standard reference sample containing 0.22×10-6 mercury, and obtained the repeatability standard deviation (S.)W of 0.002×10-°; the repeatability relative standard deviation was 0.91%,
6.1.7.2 Reproducibility
Five laboratories analyzed the above standard reference samples, and the contents of coexisting elements were respectively 56.2×10-° for mercury, 2.4×10-' for cadmium, 49.7×10-° for chromium, 45.4×10-, 71.9×10-' for copper, 0.38X10-6 for lead, and 262.7×10-6 for zinc. The reproducibility standard deviation (SR)W was 0.010×10-°, and the reproducibility relative standard deviation was 4.5%. 6.1.7.3 Accuracy
Five laboratories analyzed the above standard reference samples and obtained a relative error of 1.8%. 6.1.8 Precautions
6.1.8.1 Make sure that the instruments used are clean. New instruments must be soaked in nitric acid for more than (1 + 1) days. Used instruments must be carefully cleaned before use.
6.1.8.2 Due to the high vapor pressure of mercury, during the experiment, it is necessary to prevent the loss of mercury and the contamination of the sample and reagent by mercury in the air. The digestion time of the sample and the blank should be as similar as possible, and the reagent should be prevented from contacting with the air. The use time of the prepared reagent should not be too long. 6.1.8.3 In order to ensure the accuracy of the analysis results, the sample weighing amount and the volume of the sample digestion solution measured can be appropriately adjusted to make the measured value within the range of the standard curve.
6.1.8.4 Since the volume of the solution in the reaction bottle has an impact on the determination, add an appropriate amount of water to control the volume of the solution to about 50mL. 6.1.8.5 When formulating the standard curve, use the same reaction bottle, which is convenient to operate and can reduce the generation of random errors. At this time, first add 2mL of stannous chloride solution to the reaction bottle, and then add 20, 40, 60, 80, and 100μL of mercury standard solution (6.1.3.1.3) respectively. Quickly cover the bottle stopper and proceed according to the steps for drawing the standard curve. 6.2 Dithiol Spectrophotometry
6.2.1|Scope and Application Field
This method is applicable to the determination of total mercury in marine sediments and general terrestrial sediments. For sediments with serious mercury pollution, the sample dosage can be appropriately reduced.
Detection limit (W): 30×10-9
6.2.2 Principle of the Method
After the sample is digested, the mercury in it is converted into ions, which are then reduced to atomic mercury by stannous chloride. The mercury is aerated to gaseous state and enters the potassium permanganate absorption solution with the carrier gas. The absorption solution is then extracted with a dithiol-carbon tetrachloride solution, and the mercury ions react with dithiol to form an orange chelate, which is photometrically determined at a wavelength of 485nm. 6.2.3 Reagents and their preparation
GB17378.5—1998
Unless otherwise specified, all reagents used are analytically pure and water is mercury-free deionized water or equivalent pure water. 6.2.3.1 Mercury standard solution
6.2.3.1.1 Mercury standard stock solution: 1.000 mg/mL, see 6.1, 3.1.1.
6.2.3.1.2 Mercury standard intermediate solution: 10.0 μg/mL, see 6.1.3.1.2.
6.2.3.1.3 Mercury standard working solution: 1.00 μg/ml, see 6.1.3.1.3.
6.2.3.2 Sulfuric acid solution: 1+1
Inject 1 volume of sulfuric acid (H,SO4, p=1.84g/mL, high-grade pure) slowly along the wall of the cup into 1 volume of water (stirring while injecting). 6.2.3.3 Potassium permanganate solution: 50g/1
See 6.1.3.4.
6.2.3.4 Absorption solution
Mix 10mL of sulfuric acid solution (6.2.3.2) and 10mL of potassium permanganate solution (6.2.3.3), add water to 100mL, and mix well. Prepare before use.
6.2.3.5 Stannous chloride solution: 100g/L
See 6.1.3.2.
6.2.3.6 Dithiocarbamide-carbon tetrachloride solution:
6.2.3.6.1 Dithiocarbamide stock solution: 0.4mg/ml Weigh 100mg of dithiocarbamide (C.HsN:NCSNHNHC.H,) into a 200mL beaker, add 100mL of chloroform to dissolve, filter through glass fiber (first soaked in 1+1 nitric acid overnight, then washed with water), and place the filtrate in a 250mL conical separatory funnel. Extract twice with (1+50) ammonium hydroxide solution (100mL each time), discard the organic phase, and combine the aqueous phases. Wash the aqueous phase three times with carbon tetrachloride (30mL each time), and discard the organic phase. Add (1+2) hydrochloric acid until the aqueous solution is acidic (dithiocarbamide precipitates at this time). Extract twice with 250mL of carbon tetrachloride by shaking, combine the organic phases, and then filter the organic phase into a brown reagent bottle through a separatory funnel plugged with absorbent cotton. Cover the sulfuric acid solution of hydroxylamine hydrochloride (a mixture of 10 mL of purified 10% hydroxylamine hydrochloride and 10 mL of c(HSO)=1 mol/L sulfuric acid) on the surface of the organic phase and store it in a refrigerator for later use.
6.2.3.6.2 Dithiol working solution: T=70% Take 1.00 mL of dithiol stock solution (6.2.3.6.1) in a 10 mL stoppered colorimetric tube, add carbon tetrachloride (6.2.3.12) to the mark, and mix well. Use carbon tetrachloride (6.2.3.12) as the reference solution to adjust the zero point, and measure the absorbance value A at a wavelength of 500 nm using a 1 cm measuring cell. To prepare a dithiolone solution with a transmittance of T = 70% in VmL, the volume (VmL) of the dithiolone stock solution (6.2.3.6.1) to be measured can be calculated as follows:
This solution should be placed in a brown ground-mouth reagent bottle and prepared before use. 6.2.3.7 Hydroxylamine hydrochloride solution: 100g/L
See 6.1.3.3.
6.2.3.8 Ammonia solution: CNHOH = 1 mol/L Take 500mL of ammonia water (p = 0.90g/mL) and 500mL of water in two beakers respectively, place them in the same empty desiccator, cover them, and leave them for more than two days and nights. The ammonia water after absorption and purification is calibrated with 1mol/L hydrochloric acid and then diluted with water to 1mol/L. 6.2.3.9 Disodium ethylenediaminetetraacetate solution: 50g/L Weigh 5g disodium ethylenediaminetetraacetate (EDTA-2Na·2H,O), dissolve it in water and dilute it to 100mL. Extract it several times with 5mL disulfide solution until the organic phase turns green, discard the organic phase, and put the aqueous phase into a dropper bottle. 6.2.3.10 Nitric acid (HNO3): 0=1.42g/mL, high-grade pure. 568
GB 17378. 5-1998
6.2.3.11 Hydrogen peroxide (H,O,): 30%, high-grade pure. 6.2.3.12 Carbon tetrachloride (CCl,).
6.2.4 Instruments and equipment
Spectrophotometer;
-Aeration-absorption device (Figure 3);
-Electric constant temperature water bath;
-Water pump or medical syringe;
-General laboratory instruments and equipment. Connect the vacuum pump
1-gas flowmeter; 2-active gas sampling tube, 3-mercury vapor generation bottle Figure 3 Aeration-absorption device diagram
6.2.5 Analysis steps
6.2.5.1 Drawing a standard curve
6.2.5.1.1 Take 6 25mL stoppered colorimetric tubes, add 0, 1.00, 2.00, 3.00, 4.00, 5.00mL of mercury standard solution (6.2.3.1.3) respectively, and then add 10.0mL of absorption solution (6.2.3.4) to each, and add water to 20mL. 6.2.5.1.2 Add the same amount of hydroxylamine hydrochloride solution (6.2.3.7) as the sample to be measured, shake until the red color fades, and leave it open for 30 minutes. 6.2.5.1.3 Add 5.0mL of disulfide solution (6.2.3.6.2), shake vigorously for 3 minutes (open the lid to release air once), and let it stand to separate. Use a water pump (or medical syringe) to absorb the upper aqueous phase, wash the organic phase with water two to three times (use 20mL of water each time, shake for 1 minute), and absorb the aqueous phase.
6.2.5.1.4 Add 10mL of nitrogen aqueous solution (6.2.3.8) and 2 drops of EDTA-2Na solution (6.2.3.9), shake 30 times, let it stand to separate, and absorb the aqueous phase in the same way as above. Add 10mL of ammonia solution (6.2.3.8) and shake 30 times, pour the organic phase and aqueous phase into a 50mL separatory funnel together, and let it stand to separate. Insert absorbent cotton into the neck of the separatory funnel. 6.2.5.1.5 Filter the organic phase into a dry 1 cm measuring cell, adjust to zero with carbon tetrachloride (6.2.3.12), and measure the absorbance (A,) and the standard blank absorbance (A.) at a wavelength of 485 nm. Record the data in Table A1 of Appendix A of GB17378.4-1998. 6.2.5.1.6 Draw a standard curve on centimeter square paper with (A,--A.) as the ordinate and the corresponding micrograms of mercury as the abscissa. Paste the standard curve in the calibration curve column of Table A1 of Appendix A of GB17378.4-1998. 6.2.5.2 Sample digestion
Weigh 4~6g (±0.01g) of sediment wet sample, place in a 150mL conical flask, add 20mL nitric acid (6.2.3.10) and digest in a 90℃±5℃ water bath for 1.5h, shaking every 20min. Add 2mL hydrogen peroxide (6.2.3.11) and continue digestion for 0.5h. Take out and cool slightly, add 5mL potassium permanganate solution (6.2.3.3), and place for more than 0.5h. The red color of potassium permanganate should not fade. Otherwise, potassium permanganate solution (6.2.3.3) should be added until the red color does not fade. At the same time, make an analytical blank. 6.2.5.3 Sample determination
6.2.5.3.1 Add hydroxylamine hydrochloride solution (6.2.3.7) When the red color of the digestion liquid fades, transfer the digestion liquid and the residue into a 250mL mercury vapor generating bottle, wash the conical bottle with 100mL of water three times, and combine the washing liquid into the mercury vapor generating bottle. 6.2.5.3.2 Take two absorption tubes, add 10mL absorption liquid (6.2.3.4) to each, and connect the gas system according to the aeration-absorption device schematic diagram (Figure 3). The first-stage absorption tube is to remove mercury in the carrier gas and does not need to be replaced every time. 569
GB 17378. 5—1998
6.2.5.3.3 Add 4mL of stannous chloride solution (6.2.3.5) to the mercury vapor generating bottle and immediately plug the bottle stopper. Connect the vacuum pump and aerate at a flow rate of 1500mL/min for 15min. During the aeration process, shake the mercury vapor generating bottle once every few minutes to fully stir the residual liquid. 6.2.5.3.4 Remove the second-stage absorption tube and transfer the absorption solution into a 25mL stoppered colorimetric tube. Wash the absorption tube three times with a total of 10mL of water, and add the washing solution into the colorimetric tube. Add hydroxylamine hydrochloride solution (6.2.3.7) dropwise until the red color fades, then add 2 more drops of hydroxylamine hydrochloride solution (6.2.3.7), mix thoroughly, open the lid and leave for 30 minutes. Determine the sample absorbance value (A.) and the analytical blank absorbance value (A,) according to steps 6.2.5.1.3 to 6.2.5.1.5. Use the (A.-Ab) value to find the corresponding micrograms of mercury from the standard curve. 6.2.6 Record and calculation
Record the measured data in Table A2 of Appendix GB17378.4-1998, and calculate the total mercury content in the dry sediment sample according to the following formula: m
WHg = M(1- WH,o)
Total mercury content in dry sediment sample, mass ratio, 10-°; Where: WHg---
m——the amount of mercury found from the standard curve, ug; M-the weighed amount of sample, g;
WH,o—the moisture content of the wet sample, %.
6.2.7 Precision and Accuracy
Five laboratories analyzed standard reference samples containing mercury W0.22×10-, and the contents of coexisting elements were arsenic W56.2×10-6, cadmium W2.40×10-6, chromium W49.7×10-', copper W45.4X10-6, lead W71.9×10-6, selenium W0.38×10-°, and zinc W262.7×10-6. The repeatability standard deviation (S.) W was 3.0×10-° and the repeatability relative standard deviation was 1.4%. The reproducibility standard deviation (SR) W was 20×10-6, and the reproducibility relative standard deviation was 9.1%. The relative error was 4.6%. 6.2.8 Precautions
6.2.8.1 When digesting the sample, hydrogen peroxide must be added drop by drop to prevent the hydrogen peroxide from violently decomposing and causing the digestion liquid to splash. 6.2.8.2 After each batch of samples is digested and cooled, the amount of potassium permanganate solution added should be kept equal so that the reagent blank is kept at the same level.
6.2.8.3 In the analysis step 6.2.5.3.4, the lid is opened and left for 30 minutes to eliminate the influence of chlorine and nitrogen oxides produced by the reaction. 6.2.8.4 In the analysis step 6.2.5.1.3, the organic phase is washed with water to eliminate the interference of divalent manganese (Mn2+). 6.2.8.5 The glassware needs to be soaked in 1+1 nitric acid solution for more than 1 day and washed with water before use. 7 Copper
7.1 Flameless atomic absorption spectrophotometry
7.1.1 Scope and application field
This method is applicable to the determination of copper in marine sediments. Detection limit (W): 0.5×10-°.
7.1.2 Principle of the method
The sediment sample is digested with nitric acid-perchloric acid, and copper is measured by flameless atomic absorption at a wavelength of 324.7nm in a dilute nitric acid medium.
7.1.3 Reagents and their preparation
Unless otherwise specified, the reagents used are analytical grade, and the water is secondary deionized water or equivalent pure water. 7.1.3.1 Copper standard solution
7.1.3.1.1 Copper standard stock solution: 1.000mg/mL. Weigh 0.1000g copper powder (purity 99.99%) into a 25mL beaker, moisten with water, add 5mL (1+1) nitric acid solution (7.1.3.2-a), heat slightly on a hot plate until completely dissolved and evaporate to about 1mL, transfer the entire amount into a 100mL volumetric flask after cooling, add (1+99) nitric acid solution (7.1.3.2-b) to the mark, and mix well. 7.1.3.1.2 Copper standard intermediate solution: 100μg/mL. 5703.1.2 Copper standard intermediate solution: 100 μg/mL. 5703.1.2 Copper standard intermediate solution: 100 μg/mL. 570
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