Some standard content:
G 17378.6—1998
This standard is the sixth part of the Marine Monitoring Specifications, which is revised on the basis of the HY003.6-1991 industry standard. This standard specifies the requirements and analysis methods for organism analysis. The marine monitoring specification includes the following parts: GB 17378.1 1998
Part 1: General
Marine monitoring specification
GB 17378. 2—1998
GB 17378- 3—1998
GB 17378. 4—1998
GB 17378. 5-1998
GH 17378.6—1998
CB 17378. 71998
Marine monitoring specification
Marine monitoring specification
Marine monitoring specification
Marine monitoring specification
Marine wall monitoring specification
Exhibit A of this standard is the appendix of the standard.
This standard is proposed by the State Oceanic Administration.
Part 2: Data processing and analysis quality control Part 3: Sample collection, storage and transportation Part 1: Seawater analysis
Part 5: Sediment analysis
Part 6: Organism analysis
Part 7: Ecological investigation and biological monitoring of offshore pollution This standard is under the jurisdiction of the National Oceanographic and Marine Research Center, and is drafted by the Third Institute of Oceanography of the State Oceanic Administration. The main drafters of this standard are Xu Kuncan, Zhang Juanming, Chen Weiyue, Hong Junchao, and Chen Banglong. 614
1 Scope
National Standard of the People's Republic of China
Specification for marine monituringPart 6:Organisim analysis
CB 17378. 6 1998
This standard specifies the determination method for 13 harmful substances in marine organisms (shellfish, shrimp and fish), and puts forward technical requirements for sample collection, transportation, storage, pretreatment and calculation of determination results. This standard is applicable to the investigation and monitoring of marine biological pollution in oceans, near-penetrating and coastal waters. 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. GB17378.2-1998 Marine Monitoring Specifications Part 2: Data Processing and Analysis Quality Control CB17378.4-1998 Marine Monitoring Specifications Part 4: Seawater Analysis GB17378.5-1998 Marine Monitoring Specifications Part 5: Sediment Analysis 3 Definitions
This standard adopts the following definitions.
3.1 Evaporation to dryness Evaporation of the solvent to a small volume (0.2 mL to 1.3 mL). If there is any residue, the residue should be moist. 4 General provisions
4.1 Collection and preparation of samples
4.1.1 Sampling objects
Mussels, shrimps and fish.
4.1.2 Reagents
4.1.2.1 Deionized water or equivalent distilled water, the trace metal content of which should be lower than the detection limit of the analytical method. Or use contaminated surface seawater.
4.1.2.2 Synthetic detergent.
4.1.3 Instruments and equipment
Plastic freezer, equipped with. For mussel storage and transportation, the bottom must have a plate to prevent the sample from being immersed in the sample; a refrigerator
Low-temperature refrigerator:
Ethylene bag:
National Quality and Technical Supervision Rat 1998-06-22 approved 1999-01-01 implementation
--Plastic plate and ruler; use the lower length measurement; plastic knife
GB 17378.61998
Glass or ceramic dish (for sample preparation); forge: plastic products or other suitable materials 1 High-density polyethylene bags and plastic containers: for quick-freezing and storage of samples, before loading, they must be cleaned with synthetic detergent and washed with steamed stuffing water:
High-density polyethylene film: for covering the workbench; small sheet of vinyl film: for weighing,
. Analytical balance sensitivity 0.1mg; ||t t||Plastic washing bottle;
Scraper: for collecting mussels:
Plastic bucket: 20~-50L;
Large metal force, no rust, for cutting fish tissue; Pulper: stainless steel or other suitable materials; Plastic brush: hard brush, used to remove attachments from mussel shells; Weighing bottle: 50mL,
Electric oven:
Drying oven:
A freeze drying device.
4.1.4 Sampling and transportation
4. 1.4. 1 Preparation 1. Clean the freezer, high-density polyethylene bag, plastic plate and ruler, large metal knife, and scraper with synthetic detergent (4.1.2.2). Rinse with running water or surface seawater (4.1.2.1). 4.1.4.2 Collection of mussels
Use a clean scraper to collect mussel samples from the attachments. Select a sufficient number of intact mussels and store them in a freezer. If long-distance transportation is required (more than 2 hours on hot days), the mussels should be placed in a plastic bucket and the clean seawater collected on site should be poured over the mussels. The samples should be kept moist but not soaked in water. If sample processing must be carried out 24 hours after sampling, the mussel samples can be stored in a high-density plastic bag, the air in the bag is removed, the bag mouth is knotted or heat-sealed, and the bag and the sample label are placed in a polyethylene bag and sealed, and stored in a low-temperature refrigerator. 4.1.4.3 Collection of shrimp and small and medium-sized fish samples
Select a sufficient number of intact biological samples according to certain requirements and place them in a clean polyethylene bag. Be careful not to puncture the bag. Squeeze out the air in the bag, knot the bag or heat-seal it, and place the bag and the sample label in another polyethylene bag and seal it, and store it in a low-temperature refrigerator. Only when the storage period is not too long (no more than 48 hours on hot days), can the samples be stored in a refrigerator or freezer. 4.1.4.4 Collection of large fish samples
Measure and record the fork length, body weight and sex of the fish sample. Use a clean knife to cut off at least 1006 muscle tissue with a thickness of at least 5cm so that when processing the sample (4.1.5.5>). Remove the contaminated or visceral parts, store in a clean polyethylene bag, squeeze out the air and seal it, put this bag together with the sample label into another polyethylene bag, seal it, and store it in a low-temperature refrigerator. If the storage time is not too long (no more than 48 hours on hot days), the effective sample can be stored in a refrigerator. 4.1.5 Sample pretreatment
4. 1. 5. 1 Preparation
If necessary, place the frozen sample in a refrigerator (-2 to 4°C) overnight to partially thaw for slicing. Clean the plastic knife, plate, spoon, plastic plate, ruler and weighing plastic film with a synthetic detergent (4.1.2.2) and rinse with distilled water or clean seawater (4.1.2.1). Cover the workbench with a clean plastic film. Wash your hands carefully with a synthetic detergent (4.1.2.2) and then rinse with distilled water or clean seawater (4.1.2.1). 4.1.5.2 Preparation of mussel samples
GB 17378. 6—1998
Remove all attachments from the outside of the shell with a plastic knife and a plastic brush. Rinse each mussel with distilled water or clean seawater (4.1.2.1) and let it flow naturally to pull out the byssus. Weigh the total weight of each individual with a balance and record the weight.
Use another plastic knife to insert into the opening of the byssus, cut the closing muscle, open the mussel (see Figure 1), wash the soft tissue inside the shell with distilled water or disinfected surface seawater (4.1.2.1), remove the soft tissue with a plastic knife and a plate, and let the water drain. 1) Single body sample: Put the soft tissue into a weighed plastic container, weigh it again, and record the fresh weight. Cover tightly and label it. Use a ruler to measure and record the length of the shell (see Figure 1).
2) Multiple body samples: Continue the above steps to put the soft tissue of at least 10 mussels into a plastic container with a known weight, weigh it, and record the fresh weight. Homogenize the sample in a homogenizer, put the homogenate back into the original plastic container, weigh it again, and record the total weight to calculate the homogenate yield. Put the sample label on the stand, shrimp body length
cut off the closed muscle
forced area
Figure 2 Shrimp body diagram
PF-pectoral wax; DF-spinal wall, dotted line indicates the cutting position. Figure 3 Fish body circumference
Each individual size should be close, and the individual length and total weight should be measured before removing the biological tissue. 4.1.5.3 Shrimp sample preparation
4.1. 5. 3.1 Individual sample
Use a ruler to measure the body length of the shrimp (see Figure 2), place the shrimp on a polyethylene sample film and weigh it, record the length and fresh weight. Nibu
Use a plastic knife to separate the abdomen from the cephalothorax and the exposed part, and carefully remove the internal organs from the abdomen (Figure 2). Remove all legs, turn the abdomen down, cut along the edge of the abdominal carapace with a plastic knife, remove the inner carapace with a plastic tweezer and discard it. Use another plastic knife to loosen the abdominal muscles and remove the muscles with a sickle, check the gonads, and record the sex of the shaved shrimp. Use a tweezer to transfer the muscles into a plastic container, weigh it and record the fresh weight. Cover the container tightly and mark it with a number. Put the containers together in the same plastic bag, attach a sample sheet, tighten the bag, and store in a low-temperature refrigerator. 4.1.5.3.2 Multiple individual samples: Prepare samples as described above, and carefully record the length, fresh weight, abdominal muscle weight and sex of each individual. Each sample must include more than 6 individual muscles of the same sex and similar size. Put the sample into a homogenizer to soften the waist muscle, transfer it into a plastic container with a known concentration of 647
GB 17378. 6-1998
salt, cover it tightly, mark it with a number, weigh it, and record the fresh weight and other data. Put several plastic containers into the same plastic bag and attach the sample cleaning leather, tighten the bag and store it in a low refrigerator. 4.1.5.4 Preparation of small and medium-sized fish samples
4.1.5.4.1 Single individual sample: Measure the length of the fish and weigh it on a polyethylene sample weighing film. Record the length and weight. Wash the fish sample with distilled water or clean surface seawater (4.1.2.1), place it on the workbench, and use a knife to cut the breast scales and cut the skin from the head to the tail of the fish (Figure 3).
Make a cut across the fish body near the gills and tail; make a cut on the abdomen, gills and both sides of the tail. Make four cuts only on one side of the fish body, and do not cut too deep to avoid cutting the internal organs and contaminating the meat slices. It is best to have another person help hold the head and tail of the fish when slicing. Use a knife to separate the fish skin from the meat slices, and be careful not to contaminate the meat slices with the outer skin. Use another plastic knife to separate the meat from the vertebrae, and use a tweezers to remove the muscles. Put the tissue into a plastic container, weigh and record the amount. If the muscle on one side is not enough for analysis, take muscle from the other side to supplement. Cover the container tightly, label or mark it, record all data, and store it in a low-temperature refrigerator. Identify the sex of the gonads.
4.1.5.4.2 Multiple test specimens: Preparation method is as follows. Carefully record the length, fresh weight and muscle weight of each specimen. Identify the sex. The number of specimens should not be less than 6. The specimens should be of the same sex and similar size. Use a homogenizer to homogenize the tissue, transfer the homogenate into a plastic container of known weight, cover tightly, label it, weigh it and record the homogenate weight and other data. Store it in a low temperature refrigerator. 4.1.5.5 Preparation of plastic fish samples
If necessary, place the samples collected on site (4.1.4.4) in a refrigerator for 2 to 4 hours overnight to partially thaw for slicing. Wash the fish sample with distilled water or clean seawater (4.1.2.1) and place it on a clean workbench. Remove the remaining skin and bones, cut off the dead layer with a plastic knife, and repeat the operation with another plastic knife. Leave a uniform muscle tissue that is not contaminated. Place the meat tissue in a material container, cover it tightly, label it, weigh it, record all the data in the record sheet, and store the sample in a low-temperature refrigerator. 4.1.5.6 Sample preparation
Dry some fresh samples according to step 4.1.6-1 or 4.1.6.2, calculate the 1/wet ratio to correct the moisture content, grind the dried samples in a mortar, and sieve all of them through 80-100 mesh (nylon sieve) for trace element analysis. 4.1.6 Gravity determination
4.1.6.1 Drying 1-
Half-open the ground cover of the weighing bottle and put it in a 105℃ oven. After 2h, take out the weighing bottle and place it in a desiccator to cool for 30min. Cover the bottle cap, weigh it on the analytical level, and record the weight. Take 5 to 10 g of the biological preparation sample (1.1.5) in a weighing bottle, cover the bottle, weigh the weight (+0.5 ml) and record the weight ratio.
Put the weighing bottle with the sample half-opened into a 105°C oven. Take it out after 24 hours, cool it in a desiccator for 30 minutes, cover the bottle and weigh it and record the highest weight.
Repeat the drying operation until the weight difference between the two dryings is less than 0.5% of the total weight. Calculate the dry weight and dry/wet ratio. 4.1-6.2 Cold drying
For biological samples with high lipid content, if they cannot be dried to constant weight, freeze drying is required. Accurately weigh 1 to 2 g of the biological preparation sample (1.1.5) in a clean freeze-dried sample container and freeze-dry for 24 hours. h, and weigh again. Freeze and dry for 24h, and weigh again. The difference between the two weighings should be less than 0.5% of the total weight. Otherwise, continue to dry until the sample meets the requirements
and calculate the weight/humidity ratio (F).
4.1.7 Notes
4.1, 1 Mussels collected from places other than the laboratory do not have special transportation and storage problems. When transported to the laboratory, the samples must be ventilated and kept moist with seawater. Mussels collected from the intertidal zone can survive in the air for 24h. Mussels immersed in seawater will absorb water and excrete waste. When the mussels are in the air, their shells are closed and their metabolic rate is greatly reduced. Therefore, the mussels should not be placed in water during transportation. RA
GB 17378.6—1998
4.1.7.2 After washing, the anatomical tissue should not be touched. It is best to wear a protective film: If conditions permit, preparatory work and sample preparation should be carried out under clean conditions.
4.1.7.3 When preparing multiple samples, organisms of the same sex, size and similarity should be selected. Before removing the soft tissue, the length and weight of each individual should be measured separately.
4.1.7.4 Before sample digestion, compare the total weight of the container containing the sample with the weight at the time of storage to find out whether the sample has lost weight during storage.
4.1.7.5 The amount of metal traces in muscles of different parts may be different, so the relevant information of the actual sample should be recorded as detailed as possible. 4.1.7.6 For biological samples measured with organic pesticides and petroleum hydrocarbons, the equipment and The reagents should be changed appropriately. Plastic containers and reagents containing halogenated hydrocarbons or hydrocarbons should be avoided. 4.1.7.7 For the determination of total and harmful organic matter in organisms, dried samples should not be used. In this case, wet samples should be used for measurement, and the results are still expressed as the amount of the analyte in the dry sample.
4.2 Requirements
4.2-1 Drying of analytical samples: When the drying temperature and time are not specified, it means 105℃±1℃, drying for 2h. 4.2.2 In the preparation of standard solutions, all pipettes should be calibrated in advance. Volumetric bottles should be of first-class quality. 4.2.3 Purification of all containers, unless otherwise specified, should be soaked in (1+3) nitric acid for 2~3d, then rinsed with deionized water, and stored for use.
4.2.4 Data processing shall be carried out in accordance with the requirements of GB17378.2--1998. 4.2.5 Except for the measurement method specified in the text, the pH value can be measured by precision or wide pH test paper. Table 1 The proportion of inspection samples taken from the analysis samples Number of analysis samples
Inspection sample extraction percentage
10-~30
4.2.6 In order to check the quality of the analysis results, the business department shall take inspection samples from a batch of analysis samples according to any axis in Table 1, pack them separately and assign sample numbers. The basic samples and inspection samples shall be handed over to relevant personnel for measurement. 4.2.6.1 The measurement items of the inspection samples are the same as those of the basic samples. 4.2.6.2 When the number of analysis samples is large, the basic samples and inspection samples do not need to be arranged in the same batch for testing. 4.2.6.3 The test results shall be summarized by the business department, and the analysis quality shall be controlled according to the relative deviation value of the two samples listed in Table 2. When the deviation rate of the inspection results of the two samples 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 deviations still occur, the competent department and analysts should carefully check and analyze the reasons (such as the preparation of standard liquid, environmental quality, abnormal conditions of all instruments and equipment, etc.) before conducting measurements on this batch of analysis samples (basic samples and inspection samples). When the deviation rate of the double sample inspection result of a certain test item is less than: 3(%, the sample with deviation shall be re-weighed and measured until the new measurement result is qualified. The result shall be reported according to the average of the parallel double samples. 2. Table of relative deviation of parallel double samples
Division result level
Relative deviation limit (%)
Blxia%
Calculation:
Each batch of samples analyzed (about 20) shall be inserted with 2 to 3 standard samples (separately numbered) by the business department to check the systematic error.
4.3.1 The density of various acids and bases (0) refers to g/ml at 20°C. 4.3.2 When the desiccant is not specified, it refers to color-changing silica gel. 4.3.3 The concentration of the prepared standard solution of the element refers to the concentration of the element. 4.3.4 Solutions without specified solvents are all aqueous solutions. S19
5 Measurement items.Methods and detection limits
Measurement items and detection limits are shown in Table 3.
Analysis methods
Cold atomic absorption spectrophotometry
Double-phase atomic absorption spectrophotometry
Flameless atomic absorption spectrophotometry
Anodic falloff voltammetry
Flame atomic absorption spectrophotometrywww.bzxz.net
Diethylthiocarbamate
Spectrophotometry
Flameless semi-absorption spectrophotometry
Anodic stripping voltammetry
Flame atomic absorption spectrophotometry
Double-phase atomic absorption spectrophotometry
Anodic latent voltammetry
|tt||Spectrophotometry
Hydrocarbon
6Total mercury
Fluorescence spectrophotometry
Gas chromatography
6.1 Cold atomic absorption spectrophotometry
6-1.1 Applicable scope and application field
GB17378.6—1998
3 Measurement item method detection limit
1Average limit W(10\）
1(wet content)
a-6663pg
Y6667pg
β-6668pg
g-6669pg
p'-8
-DT 40Pg
Analysis method
Annual carbon number di-cake spectrophotometry
Non-flame source electron absorption spectrophotometry
Arsenic acid-silky violet spectrophotometry
Exceeding limit W0)
Quick product atomic absorption spectrophotometry!
Catalytic polar harmonic method
Non-flame atomic absorption valence light diffusion method
Polar dropout voltammetry
Flame source electron absorption spectrophotometry
Dithiol spectrophotometry
Fluorescence spectrophotometry
Diaminobenzamide tetrahydrochloride spectrophotometry
Catalytic spectroscopy
Multiple oxygen gas chromatograph
Qiu's agent
Gas chromatography
This method is suitable for the determination of total mercury in marine organisms. For biological samples with high iodine content: an appropriate amount of silver nitrate should be added to eliminate the interference of iodine on the determination.
Lower detection limit (W): 0.01X10-6
6. 1.2 Principle of the method
Use vanadium pentoxide as a catalyst, digest the biological sample with nitric acid-sulfuric acid, convert all organic mercury into inorganic mercury, then use vanadium chloride to reduce the mercury ions into metallic mercury, and use a gas-liquid equilibrium open-circuit aspiration cooled atomic absorption measurement system to measure the total amount of mercury at a wavelength of 253.? nm. 6.1.3 Reagents and their preparation
Unless otherwise specified, all reagents used are analytically pure, and water is deionized water or equivalent pure water. 6.1.3.1 Vanadium pentoxide (V0.)
6.1.3.2 Anhydrous calcium fluoride (CaCl,), used to fill the coal pipe. 6.1.3.3 Nitric acid (HNO,): 0 = 1.42 g/mL. 6.1.3.4 Sulfuric acid (H,SO,): 0-1.84 g/mL, process ultrapure. 6.1.3.5 Sulfuric acid solution: 0.5 mol/LAS!
GB17378.61998
Add 28 mL of sulfuric acid (6.1.3.4) to 972 mL of water while stirring. 6.1.3.6 Hydrochloric acid solution: 1+1
Mix hydrochloric acid (HCE.p=1.19%/mL) with an equal volume of water. 6.1.3.7 Nitric acid solution: 1+19
Mix 1 part of nitric acid (6.1.3.3) with 19 parts of water. 6.1.3.8 Tin nitride solution: 100g/1, weigh 10g of tin nitride and add it to a beaker + add 100ml of hydrochloric acid solution (6.1.3.6), heat until dissolved, cool and put it in a brown bottle, dilute with an equal volume of water when using, if the mercury impurity content is high, it can be removed by bubbling method until the mercury content in the solution cannot be detected. 6.1.3.9 Low mercury seawater; Filter the surface seawater through filter paper, slowly add 28mL of sulfuric acid (6.1.3.4) to each liter of seawater to acidify, the mercury content of seawater should be less than 0.005g/L
6.1.3.10 Standard preparation solution: 1.00tmg/mL Weigh 0.1354g of mercuric oxide (HgCl) (pre-dried in a sulfuric acid dryer) in a 10mL beaker, dissolve it with nitric acid solution (6.1.3.7). Transfer the whole amount to a 100ml volumetric flask, dilute to the mark with nitric acid solution (6.1.3.7), mix well, and keep for one year. 6.1.3.11 Mercury standard intermediate solution: 10.0g/ml Measure 1.00ml of standard stock solution (6.1.3.10) in a 100ml volumetric flask, dilute to the mark with nitric acid solution (6.1.3.7), mix well. Keep for one week.
6.1.3.12 Standard working solution: 0.100g/ml Measure 1.00ml of standard intermediate solution (6.1.3.11) in a 100ml volumetric flask, dilute to the mark with sulfuric acid solution (6.1.3.5), mix well.
6.1.4 Instruments and equipment
Mercury measuring device (Figure 4) 4
1 Vacuum pump; 2 Air flow regulating valve; 3- Exhaust gas absorber: 4- Mercury measuring instrument; 5- Light absorption cell + 6- Drying tube; ?- Three-way fitting, 8 Mercury vapor generating bottle: 9- Air purification device + 11- Gas flow meter Figure 4 Cold atomic absorption mercury measuring device
Mercury vapor generating bottle: 250ml. Conical washing bottle modification. Cut off the lower end of the washing bottle ventilation tube so that the tube end just leaves the liquid surface to be measured, an electric heating plate: covered with about 3 cm thick fine sand; Laboratory instruments and equipment.
6.1.5 Analysis steps
6.1.5.1 Draw the standard curve
6.1.5.1.1 Take 6 250mL vapor generation bottles, add 100mL low-mercury seawater (6.1.3.9), and then add 0, 0.10, 0.20, 0.30, 0.40, and 0.50mL of mercury standard working solution (6.1.3.12) respectively, and mix. 6.1.5.1.2 Turn the switch on the mercury meter to the zero position, and pass the light absorption cell with a flow rate of 1~1.51/min. 6.1.5.1.3 Connect the vapor generation bottles to the mercury meter in turn. Add 2mL of chlorinated sodium solution (6.1.3.8), quickly close the stopper of the vapor generation bottle, and shake for 1 minute.
6.1.5.1.4 Adjust the zero point of the measuring instrument, turn the three-way switch to the determination mode, and measure the absorbance value A; and the standard blank absorbance value A. 6.1.5.1.5 Fill in the data in Table A5 of Appendix GB17378.4-1998. Use the absorbance value A:-A. as the ordinate and the corresponding content (ug) as the abscissa to draw a standard curve. 6.1.5.2 Sample digestion
GB 17378.61998
Accurately weigh 2.5g (0.0018) of the mixed sample and put it into a 100tmL high beaker, add 40mg of vanadium oxide (6.1.3.1) and 8ml of nitric acid (6.1.3.3), cover with blood, and heat on a 140~160℃ electric heating plate for 10min. Remove and cool slightly, add 15ml sulfuric acid (6.1.3.4), and continue heating for 20min. Remove, cool and add 10mL water, and heat for another 30min. Remove and cool, transfer the entire amount to 100ml. Add water to the recording bottle and dilute to the mark. Mix and obtain the sample digestion solution. At the same time, prepare the analytical test solution. 6.1-5.3 Sample determination
Take the appropriate sample preparation solution and put it in the steam generating bottle, add water to 100mL. For the rest, determine the absorbance value (A,) and the analytical absorbance value (A) according to the steps of 6.1.5.1.2~6.1.5.1.4. Use the value of (A.-A) to find the corresponding mercury (μg) from the standard curve. 6.1-6 Record and Calculation
Fill the sample measurement data into A1, and calculate the mercury content in the sample according to formula (1):
Wa-V,MF
Wherein: W——the total mercury content in the biological sample, ml; m-the amount of mercury found from the standard curve, rgV.\: the volume of the sample digestion liquid, ml.; V2——the volume of the sample sub-sample, ml.; M..the weighing basis of the sample.
F——the wet/wet ratio of the sample.
6.1.7 Precision and Accuracy
Six samples were measured in parallel, and their mercury content (mass ratio) was 0.25×10-, and the relative standard deviation was 1% + 4 samples were tested in the same community, and their relative standard deviation was 9.1%. 6.1.8 Notes
6.1.8.1 All curtain blood should be soaked in (1+3) nitric acid solution for more than 3 days, washed and checked for compliance. 6.1.8.2 The used steam generating bottle must be rinsed with acidic potassium permanganate solution and then washed with water. 6.1.8.3 When drawing the mercury standard curve, sodium chloride solution can also be used to replace low-mercury seawater. 6.2 Dithiol Spectrophotometry
6.2.1 Scope and Application Areas
This method is applicable to the determination of total mercury in marine organisms. Iodine has interference, so the determination of total mercury in seawater should not be directly used for this method. Detection limit: 0. 01×10-,
6.2.2 Method Original
The sample is digested with nitric acid-hydrogen peroxide-potassium permanganate, and the mercury ions are reduced to metal powder with stannous chloride. Mercury vapor is absorbed in potassium permanganate solution by the argon method. After the mercury ions react with dithiothrene, the orange complex is extracted with carbon monoxide and spectrophotometrically determined at a wavelength of 485 nm:
6.2.3 Reagents and their preparation
Unless otherwise specified, all reagents used are analytically pure, and water is mercury-free deionized water or equivalent pure water. 6.2.3.1 Nitric acid (H2O2): 0 = 1.42 g/mL, high-grade purity. 6.2.3.2 Hydrogen peroxide (H2O2): 30%, high-grade purity. 6.2.3.3 Sulfuric acid solution: 1+1, 1+40
With stirring, add 1 volume of sulfuric acid (H2O2, P = 1.81 g/mL, high-grade purity) slowly to 1 and 40 volumes of water. 6.2.3.4 Ammonium hydroxide solution c (NH4OH) = 1 mol/L. 6.2.3.5 Potassium permanganate solution: 50% potassium permanganate solution (Put in a brown reagent bottle and store in a dark place). 6.2.3.6 Stannous oxide solution: 200% potassium permanganate solution Weigh 100g of SnCl2H2O2 into a 500ml beaker. Add 500mL (1+1) hydrochloric acid solution and heat until the stannous chloride is completely dissolved. Cool and place in a brown reagent bottle. If the impurity content is to be determined, it can be removed by bubbling until no mercury can be detected in the solution. 552
6.2.3.7 Potassium permanganate absorption solution: 5g/1.
GB 17378. 6— 1998
Add 101ml.(1+1) sulfuric acid solution (6.2.3.3) to 10ml. potassium permanganate solution (6.2.3.5), add water to 100mL, mix (store in a brown reagent bottle and store in a dark place). 6.2.3.B Hydroxylamine hydrochloride solution: 1008/L
Weigh 10g hydroxylamine hydrochloride (NH,OH·HC) and dissolve in water, add water to 100mL. Use 5mL disulfide solution (6.2.3.12) to extract several times until the organic phase is green, discard the organic phase, and store the aqueous phase in a reagent bottle. 6.2.3.9 Ethylenediaminetetraacetic acid dibasic solution: 50 g/L Weigh 5 g EDTA (disodium), dissolve it in water, and add water to 100 nl. Extract several times with 5 mL dithiocarbamide working solution (6.2.3.12). 6-2:3.10 Carbon tetrachloride (CCL)
6.2.3.11 Dithiolone stock solution
Weigh 100 mg of dithiolone (C,H,N: NCSNHNHC.H,) and dissolve it in 100 mL of carbon tetrachloride (6.2.3.10), and put it in a brown reagent bottle. Store in a refrigerator.
6.2.3.12 Dithiolone working solution: transmittance 70% Determine the absorbance of the dithiolone stock solution (6.2.3.11) as follows: Take 1.00 mL of dithiolone stock solution (6.2.3.11) in a 10-liter volumetric flask, add carbon tetrafluoride (6.2.3 .10) rate mark, mix about. Adjust to zero with carbon tetrachloride (6-2.3.10), and measure its absorbance value A1 at 500nm with a 1cm measuring cell. According to the dilution factor, the absorbance value of the dithiol stock solution (6.2.3.11) is 10A1. Calculate the volume of the stock solution required to prepare a certain volume of dithiol working solution according to formula (2): Vle
V,=-10A,
wherein; V, is the volume of dithiol stock solution required to prepare V, volume of dithiol working solution, mL: the volume of dithiol working solution to be prepared, mLI-the absorbance value of the dithiol stock solution after dilution 10 times, A
-the light protection rate of the dithiol working solution to be prepared, %. This method uses 0% transmittance. (2)
Measure V. volume of dithiol preparation solution (6.2.3.11), add carbon tetrachloride (6.2.3.10) to V. volume, mix, and obtain a dithiol working solution with a transmittance of 70% (prepared when used). 6.2.3.13 Calculate the standard stock solution: 100μg/mL Weigh 0.1354g of mercuric chloride (HgCl2. Extra pure) in a 100mL beaker, dissolve it in 5mL (1+1) sulfuric acid solution (6.2.3.3). Transfer it all to a 1000mL volumetric flask, add water to the mark, and mix. 6.2.3.14 Mercury standard working solution: 1.00μg/mL Take 1.00mL of mercury standard stock solution ( 6.2.3.13) in a 100ml volumetric flask, dilute to the mark with (1+40) sulfuric acid solution (6.2.3.3), mix well, and prepare for use.
6.2.4 Instruments and equipment
Spectrophotometer;
Electric steam generator bottle: see 6.1.42,
Absorption tube: 10mL,
Vacuum pump;
Gas flowmeter:
An electric constant temperature water bath:
Standard instruments and equipment in the laboratory,
6.2.5 Analysis steps
6.2.5.1 Sample analyzation
CB17378.6:1998
Accurately weigh 10 Place 100 g (± 0.01 g) of biological wet sample in a 150 mL conical flask, add 20 mL of nitric acid (6.2.3.1), and digest overnight at room temperature. Add 5 mL of nitric acid (6.2.3.1), and digest in a 90°C water bath for 1.5 h, stirring once every 20 min. Add 2 mL of supernatant (6-2.3.2) dropwise, and continue digesting for half an hour. After cooling slightly, add potassium permanganate solution (6.2.3.5) until a large amount of brown precipitate is produced. If it does not disappear within half an hour, then add potassium permanganate solution (6.2.3.5). Prepare the sample digestion solution. At the same time, prepare the analytical blank test solution. 6.2.5.2 Draw the standard curve
6.2.5.2.1 Take a 2 mL stoppered colorimetric tube and add 10 ml of potassium permanganate absorption solution (6.2.3.7). Transfer 0, 1.00, 2.00, 3.00, 4.00, and 5.00 ml of the standard working solution (6.2.3.14) respectively. Add 20 ml of water. Add hydroxylamine hydrochloride solution (6.2.3.8) until the red color disappears: add 2 drops.
6.2.5.2.2 Add 5.00 ml of disulfide working solution (6.2.3.12), shake vigorously for 2 min (pay attention to degassing), and let it stand for stratification. Aspirate the upper aqueous phase. Wash the organic phase with water 2 to 3 times (use 20 ml of water each time), and aspirate the aqueous phase. 6-2.5.2.3 Add 2 drops of EDTA (disodium) solution (6.2.3.9), wash twice with ammonium hydroxide (6.2.3.4) solution, 10 mL each time, and transfer the organic phase to a 60 ml conical separatory funnel (with absorbent cotton plugged in the neck of the tube). 6.2.5.2.4 Filter the organic phase into a 1 cm measuring cell, adjust to zero with carbon tetrachloride (6.2.3.10), and measure the absorbance value A. and the standard blank absorbance value A: at a wavelength of 485 nm.
6.2.5.2.5 Record the measured values in Table A4 of Appendix GB17378.4-1998, and draw a standard curve with the absorbance value (A.-A,) as the ordinate and the corresponding amount of mercury () as the abscissa. 6.2.5.3 Sample determination
6.2.5.3.1 Add hydroxylamine hydrochloride solution (6.2.3.8) dropwise into the sample preparation solution until the red color disappears completely. Transfer the entire amount into a 250ml steam generating bottle. Wash the conical flask three times with 100L of water. Combine the washed solutions in the steam generating bottle. 6.2.5.3.2 Take two 10mL absorption tubes and add 10mL of absorption solution (6.2.3.7) to each. Use one tube as an air purification tube and the other as a sample steam absorption tube. Connect the gas system according to the diagram of the aeration-absorption device. The air purification absorption tube does not need to be replaced every time. Extraction gas system
1-...-gas flowmeter, 2-core gas sampling tube, 3-steam generation bottle Figure 5 Aeration-absorption device diagram
6.2.5.3.3 Add 2ml of tin nitride solution (6.2.3.6) to the mercury vapor generation bottle and immediately plug the bottle stopper. Connect the air pump and heat it at an air vortex speed of 1500mL/min for 15min. 6.2.5.3.4 Remove the vapor absorption tube and transfer the absorption liquid to a 25mL stoppered colorimetric tube and use 10ml.Wash the absorption tube three times with water and place the washed sample into a colorimetric tube. Add the hydroxylamine solution (6.2.3.8) until the red color fades, then add 2 drops more, shake thoroughly, and let stand for 30 min.
6.2.5.3.5 Follow the steps 6.2.5.2.2 to 6.2.5.2.4 to determine the absorbance value (A,2) of the sample preparation solution. At the same time, determine the absorbance value A of the analytical space according to the above steps.6. 2.6 Record and Calculation
Record the measured data in Table A1, and calculate the total mercury content in the biological dry sample according to formula (3): Wue=FM
Wherein: W is the mass ratio of the total mercury content in the biological sample, 10-654
GB17378.6-1998
m is the amount of mercury found from the standard curve, ; F... is the wet ratio of the sample;
M is the sample weighing basis, g.
6-2.7 Precision and Accuracy
Five laboratories measured the sample with a mass ratio of mercury of 0.29×10-6, and the repeatability relative to the standard deviation was 0.95%. At 0 2Hg was added to .5g of pig liver component analysis standard material (GBW08551), and the average recovery rate was 95.9%. 6.2.8 Precautions
6.2.8.1 When digesting the sample, hydrogen peroxide needs to be added drop by drop to prevent the peroxide from decomposing more violently and the digestion liquid from splashing and causing loss. 6.2.8.2 In the sample determination step 6.2.5.3.4, the lid is opened and left for 30 minutes to eliminate the influence of fluorine gas and nitrogen oxides produced by the reaction.
6.2.8.3 In the sample determination step 6.2.5.2.2, the storage phase is washed with water to eliminate the interference of manganese. 6.2.8.4 All glassware needs to be dissolved with (1+3) nitric acid Soak in liquid for 1 day and then wash before use. 7 Copper
7.1 Flameless atomic absorption spectrophotometry
7.1.1 Scope and application area
This method is applicable to the determination of marine organisms. Detection limit (W): 0.4X10*.
7.1.2 Principle of the method
The biological sample is digested with nitric acid and hydrogen peroxide, and then directly measured by atomic absorption spectrophotometry at a wavelength of 324.7nm. 7.1.3 Reagents and their preparation
Unless otherwise specified, all reagents used are analytically pure, and water is secondary deionized water or equivalent pure water. 7.1.3.1 Nitric acid (HNO.>: P1.4 2&/ml high-grade pure, distilled in a quartz sub-boiling distiller 7.1.3.2 Hydrogen perfluoride (H0,) 130%, 7.1.3.3 Copper standard stock solution: 1.000mg/ml Weigh 0.2000g of metal copper powder (purity 99.99%) in a 50mL beaker, add 5mL (1+2) nitric acid solution, heat to dissolve and cool, transfer the entire amount to a 200mL volumetric flask, add water to the mark, and mix. 7.1.3.4 Standard medium solution: 100/ml.
Measure 10.0ml. Copper standard stock solution (7.1.3.3) in a 100mL base bottle, add (1+99) nitric acid solution to the mark, and mix. Prepare when using.
7.1.3.5 Copper standard solution: 2.000μg/mL Measure 2.00mL copper standard intermediate solution (7.1.3.4) in a 100ml volumetric flask, add 1+99) nitric acid solution to the mark, and mix with a spoon. Prepare when using.
7.1.4, Instruments and Equipment
Graphite furnace atomic absorption spectrophotometer: equipped with automatic sample injection device-copper hollow cathode lamp +
Argon gas cylinder: purity 99.99%:
A clean workbench (clean 100 grade);
Electric heating plate.
7.1.5 Analysis steps
7.1.5.1 Sample digestion
7.1.5.1.1 Accurately weigh 0.1g (±0.001g) of sample into a 50mL beaker, moisten the sample with a few drops of water, add 2ml of nitric acid (7.1.3.1), cover the surface with blood, and heat on a hot plate at low temperature until the foam is basically gone.
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