HJ 897-2017Water quality. Determination of chlorophyll a. Spectrophotometric method (English PDF)

Foreword

In order to implement the "Law of the People's Republic of China on Environmental Protection" and the "Law of the People's Republic of China on Prevention and Control of Water Pollution", protect the environment, Protection of human health, regulate water chlorophyll a determination method, the development of this standard.

This standard specifies the determination of chlorophyll a surface water spectrophotometry.

This standard is released for the first time.

This standard by the Environmental Protection Department of Environmental Monitoring Division and Science and Technology Standards Division to develop.

This standard was drafted. Liaoning Provincial Environmental Monitoring Laboratory.

This standard verification unit. Shanghai Environmental Monitoring Center, Dalian City Environmental Monitoring Center, Dandong City Environmental Monitoring Center Station, Liaoyang City Environmental Monitoring Station, Chaoyang City Environmental Monitoring Center Station and Liaoning North Environmental Testing Technology Co., Ltd.

This standard MEP approved on December 21, 2017.

This standard since February 1, 2018 implementation.

This standard is interpreted by the MEP.

1 Water quality chlorophyll a spectrophotometric method

Warning. acetone on human health have some hazards, the operation should be carried out in a fume hood, wear protective equipment, to avoid Touch skin and clothing.

1 scope of application this standard specifies the determination of chlorophyll a in water spectrophotometry.

This standard applies to the determination of chlorophyll a in surface water.

This standard determination of acetone extract of chlorophyll a detection limit of 0.04 mg/L. When the sample volume is.200 ml, acetone when the volume of extract was 10 ml, the detection limit of this method was 2 µg/L and the lower limit of determination was 8 µg/L.

2 Normative references

This standard references the following documents or the terms. For undated references, the effective version applies to this book standard.

GB/T 14581 water quality lake and reservoir sampling technical guidance HJ 494 water sampling technical guidance HJ/T 91 Technical Specifications for Surface Water and Sewerage Monitoring

3 Method principle

A certain amount of sample is filtered through a filter to trap the algae, ground and broken algae cells, extracted with acetone solution chlorophyll, centrifuged After the separation, the absorbance of the extract was measured at the wavelengths of 750 nm, 664 nm, 647 nm and 630 nm, respectively, according to the formula Calculate the concentration of chlorophyll a in water.

4 Reagents and materials

Unless otherwise specified, the analysis of the use of analytical reagents in line with national standards, experimental water for the newly prepared deionized Water or distilled water.

4.1 Acetone (CH3COCH3).

4.2 Magnesium carbonate (MgCO3).

4.3 acetone solution. 9 1.

Add 100 ml of experimental water to 900 ml of acetone (4.1).

4.4 Magnesium carbonate suspension.

Weigh 1.0 g of magnesium carbonate (4.2), add 100 ml of experimental water, stirred into a suspension (shake well before use).

4.5 glass fiber filter. Diameter 47 mm, pore size 0.45 µm ~ 0.7 µm.

25 Apparatus and equipment

5.1 Sampling bottle. 1 L or 500 ml brown glass bottle with ground plug.

5.2 filter device. with vacuum pump and glass sand core filter device.

5.3 Grinding device. glass mortar or other tissue grinder.

5.4 Centrifuges. relative centrifugal force can reach 1000 × g (speed 3000 r/min ~ 4000 r/min).

5.5 Glass graduated centrifuge tube. 15 ml, capping material does not react with acetone.

5.6 visible spectrophotometer. with 10 mm quartz cuvette.

5.7 Needle Filter. 0.45 µm Teflon organic phase filter.

5.8 General laboratory equipment and equipment.

6 samples

6.1 Sample Collection the samples were collected according to the relevant provisions of GB/T 14581, HJ/T 91 and HJ 494. Sample collection in general Use a plexiglass collector or other suitable sampler to collect sub-surface 0.5 m samples, lakes and reservoirs as needed Stratified sampling or mixed sampling, volume of 1 L or 500 ml. If the sample contains settled solids (such as sediment, etc.) the sample should be shaken and poured into a 2 L graduated cylinder, protected from light for 30 min, taken 5 cm below the surface of the sample, and transferred to a sampling bottle (5.1).

Add 1 ml of magnesium carbonate suspension (4.4) per liter of sample to prevent acidification from causing pigment dissolution.

Note. If the water depth is less than 0.5 m, collect the sample at 1/2 water depth, but do not mix it with surface floats.

6.2 Sample Storage

Samples collected should be stored at 0 °C ~ 4 °C dark, transported within 24 h to the testing laboratory filtration (if the sample 24 h can not be sent to testing laboratories, should be on-site filtration, filter dark transport), sample filter at -20 °C light protection Save, within 14 d analysis is completed.

Note. After the sample is collected, the conditions should be analyzed as soon as possible.

6.3 Sample Preparation

6.3.1 Filtering

Install a glass fiber filter (4.5) on the filter unit (5.2). According to the nutritional status of water to determine the sampling volume, see

Table 1, the amount of the cylinder to take a certain volume of mixed samples, filtered, and finally with a small amount of distilled water rinse the filter wall. When filtering

Negative pressure does not exceed 50 kPa, the sample has just been completely filtered through the filter when the end of filtration, tweezers filter out, will have the sample Fold the filter paper dry with filter paper.

Note. Centrifugation can be used to concentrate samples only when samples of eutrophic water do not pass through the fiberglass filter, but should be preserved during transfer Card extraction efficiency, to avoid the loss of chlorophyll a and water on the concentration of acetone solution.

3 Table 1 refers to the filtered sample volume Nutritional status Nutritional nutrition Nutritional nutrition Filter volume (ml) 100 ~.200 500 ~ 1000

6.3.2 Grind

The sample filter placed in the grinding device (5.3), add 3 ml ~ 4 ml of acetone solution (4.3), ground to a paste.

Additional 3 ml ~ 4 ml acetone solution (4.3), continue grinding, and repeated 1 or 2 times to ensure adequate grinding more than 5 min.

The completely broken cell extract was transferred to a glass graduated centrifuge tube (5.5), and the mortar was rinsed with an acetone solution (4.3) and grinding pestle, together into the centrifuge tube, set the volume to 10 ml.

Note. Chlorophyll sensitive to light and acidic substances, laboratory light should be as weak as possible, can be analyzed operation, all vessels can not use acid Soak or wash.

6.3.3 soak extraction the centrifugation tube in the grinding extract thoroughly mixed oscillation, wrapped with aluminum foil, placed in 4 °C dark soak extract 2 h Above, no more than 24 h. In the soaking process to shake up 2 to 3 times.

6.3.4 Centrifuge

The centrifuge tube into the centrifuge (5.4), the relative centrifugal force 1000 × g (speed 3000 r/min ~ 4000 r/min) from Heart 10 min. The supernatant was then filtered through a syringe filter (5.7) to obtain an acetone extract of Chlorophyll a (test sample) to be tested.

6.4 Preparation of blank samples the laboratory blank samples were prepared according to the same procedure as preparation of sample (6.3) with experimental water.

7 Analysis steps

7.1 Determination of the sample the sample was moved to the cuvette, acetone solution (4.3) as a reference solution at a wavelength of 750 nm, 664 nm, 647 nm, the absorbance is measured at 630 nm.

Absorbance at a wavelength of 750 nm should be less than 0.005, otherwise it must be re-filtered with a syringe filter (5.7).

7.2 blank test

The laboratory blank sample (6.4) is determined according to the same procedure as the sample test (7.1).

48 Results Calculation and Presentation

8.1 Calculation Results the mass concentration of chlorophyll a in the sample (mg/L) is calculated according to equation (1).

) (08.0) (54.1) (85.11 7506307506477506641 AAAAAA -x--x--x= (1) where. rho1 - sample mass concentration of chlorophyll a, mg/L;

A664 - sample absorbance at 664 nm wavelength;

A647 - sample absorbance at 647 nm wavelength;

A630 - sample absorbance at 630 nm wavelength;

A750 - sample absorbance at 750 nm wavelength.

The mass concentration of chlorophyll a in the sample (µg/L) was calculated according to equation (2).

Vrho

rho 11

Where. rho-- sample mass concentration of chlorophyll a, µg/L;

rho1 - sample mass concentration of chlorophyll a, mg/L;

V1 - sample volume, ml;

V - sampling volume, L.

8.2 results indicated when the result is less than 100 µg/L, keep to the whole digit; when the result is greater than or equal to 100 µg/L, keep Three significant figures.

9 precision and accuracy

9.1 Precision

Six laboratories performed uniform surface water samples at concentrations of 5 µg/L, 11 µg/L and 25 µg/L for chlorophyll a Repeated determination, the relative standard deviation of the laboratory were. 5.6% ~ 11%, 3.1% ~ 6.0%, 1.8% ~ 5.0%; experiment the relative standard deviations were 5.2%, 8.9% and 5.9% respectively. The repeatability limits were 2 µg/L, 2 µg/L and 3 µg/L. again Current limits are. 2 µg/L, 4 µg/L, 5 µg/L.

9.2 Accuracy

In six laboratories, a uniform surface water sample containing chlorophyll-a concentrations of 11 µg/L and 25 µg/L was subjected to pure chlorophyll a the spiked samples were spiked at 9 µg/L and 28 µg/L respectively. The recoveries ranged from 83.6% to 95.9% and from 79.9% to 92.0% the final spiked recoveries were 89.2% ± 10.8% and 86.3% ± 8.8%.

510 Quality Assurance and Quality Control

10.1 Blank test

Each batch of samples should be done at least one laboratory blank test, the measurement results should be below the detection limit.

10.2 parallel sample determination each batch of samples should be measured at least 10% of the parallel double sample. When the number of samples is less than 10, at least one parallel double should be determined Kind, the relative deviation of measurement results should be <= 20%.

11 Waste treatment

The waste liquid generated in the laboratory process should be collected centrally and properly labeled, commissioned by a qualified unit.