Sampling rules for water analysis. Water sampling is an important stage of analysis. How to take a water sample for analysis

Sampling and pretreatment of soil samples for analysis

Selection of funds when creating the plastic composition of the performance

1. For chemical analysis Take a water sample:

in a cleanly washed dish (bottle), previously rinsed with the same water,

capacity 1 l with cork or rubber stopper.

2. Water sample for bacteriological analysis take:

in a bottle with a capacity 0.5 l, pre-sealed with a cotton plug and sterilized (in an oven at 1600 C for 1 hour) in the laboratory.

After sterilization is completed, the neck of the bottle is closed to protect against contamination. sterile paper cap .

Water sampling from mine well for chemical analysis

To take a water sample from mine well for chemical analysis often use the bucket at the well.

1. First 4-6 buckets water is drained, and then filled with water in a bottle for chemical analysis.

2. Pre-bottle at least 3 times rinse with tap water, and then fill so that under the cork there was little air space(5-6 cm).

Water sampling from mine well for bacteriological analysis

Before sampling water for bacteriological analysis,

1. holding the paper cap with your hand, take out the cork;

2. using alcohol torch (a cotton swab moistened with alcohol on a stick) burn the neck

3. and fill the bottle with water (without adding about 50-100 ml),

4. close the cork and fix the cap, tying it.

When sampling water from a well, equipped with a pump , standpipe or water tap initially:

1. burn the faucet with an alcohol torch,

2. then drain the water for 15 minutes with the tap fully open

3. and fill the bottle in compliance with the previously listed rules.

Stick on bottleslabel, on which they note:

· date, time and place of water collection and purpose of analysis,

then try with accompanying form sent to the laboratory as soon as possible.

ATaccompanying formindicate:

1. name, location and address of the water source;

2. characteristics of the water source (type, depth, means of water lifting, sanitary condition of the surrounding area);

3. the reason for sampling (routine examination, control after repair, infectious disease, etc.) and the purpose of the analysis;

4. data from studies performed at the source, if any;

5. date, hour of sampling, by whom it was taken, signature.

At the sampling site, determine:

water temperature,

the presence of an oily film on its surface,

transparency,

· chromaticity,

odor (see Table 15).

· If a sample of chlorinated water is taken, then on the spot they determine in it residual chlorine content.

1. Determining the smell of water

Fill the bottle 2/3 full with test water,

Close with clean cork

And shake hard.

After removing the cork, immediately draw air from the bottle into the nose and note the smell.

The strongest smell is felt at the first detection.

Check the nature of the smell :

earthy, musty, swampy, woody, putrid, moldy, indefinite

and his intensity , in points using the table. 15

To enhance the smell of water, 100 ml of water is poured into a flask, covered with glass, heated to 60 g. In a water bath, remove the glass and determine the smell.

2. Determining the taste of water.

Boil water in a flask

then cool it down to room temperature

and, typing in the mouth in small portions,

mark

flavor character:

Salty, bitter, glandular, metallic, astringent, etc.

andintensity it in points, using the table. 15.

The taste of water is determined with confidence in its safety.

3. About determination of residual chlorine.

Add to a glass of water 5 drops of 5% potassium iodide solution and 10 drops of 1% starch solution.

· If no blueing, means residual chlorine absent ,

· bluish coloration - less than 0.3 mg/l,

· faint bluing - from 0.3 to 0.5 mg/l, - №

· intensive - more than 0.5 mg/l residual chlorine.

table 15. Smell (taste) intensity in points

3 da n e 2. Determination of the dose of chlorine for water disinfection (field method ).

The dose of chlorine required for water disinfection (chlorine demand), determined by its trial chlorination.

For this purpose, to the same volumes of the studied water add different amounts1% bleach solution .

After 30 minutes contact of chlorine with water in all vessels determine the content of residual chlorine.

- Dose of chlorine equals the amount bleach , which was added to the vessel, where after the test chlorination remained0.3-0.5 mg/l residual chlorine.

Preparation of 1% bleach solution

1. Measure into the cylinder up to 99 ml distilled or transparent well water.

2. Weigh on a pharmacy scale 1 g bleach(the one that will disinfect the water).

3. Transfer weighed into a porcelain cup or mortar,

4. add a few drops of water from the cylinder to wet the bleach and with a glass rod or pestle carefully grind it until you get homogeneous slurry.

5. After that, add a small amount of water again and keep rubbing the bleach until the lumps disappear.

6. Then, while pouring water from the cylinder, transfer the suspension of bleach into a beaker or flask.

7. Rinse the cup with all the water from the cylinder, draining the rinse water into the same cup.

8. Later 10-15 min filter the received 1% bleach solution through paper filter, preferably in a dark bottle with a ground stopper.

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When sampling water from a surface reservoir or a mine well, its temperature is measured using a special thermometer (Fig. 16.1.) Or a conventional chemical thermometer, the tank of which is wrapped with several layers of gauze bandage. The temperature is determined directly in the water source. The thermometer is lowered into the water for 5-8 minutes, then quickly pulled out and the water temperature readings are taken.

Rice. 16.1. Thermometer for measuring water temperature in reservoirs, wells (a), bathometers for taking water samples for analysis (b).

Water sampling from surface reservoirs and wells is carried out using bottle meters of various designs, which are provided with double twine: for lowering the device to a given depth and for opening the vessel plug at this depth (Fig. 16.1-b).

For sampling water from flowing reservoirs (river, stream), a bathometer with a stabilizer was designed, which directs the neck of the vessel against the current.

A water sample from a water tap or equipped capturing is taken:

For bacteriological analysis, after preliminary burning of the outlet of the tap or capturing with an alcohol torch, draining water from the tap for at least 10 minutes into a sterile bottle with a capacity of 0.5 liters, with a cotton-gauze stopper, wrapped on top with a paper cap. In order not to soak the cotton-gauze stopper, the bottle is filled approximately three-quarters so that 5-6 cm of air space remains under the stopper. Dishes with a cotton-gauze stopper are sterilized in advance in an oven at 160 0 C for an hour;

For a short sanitary-chemical analysis (organoleptic indicators, main indicators chemical composition and indicators of water pollution) take up to one liter into chemically clean dishes, after rinsing it with selected water (for a complete sanitary-chemical analysis, 3-5 liters of water are taken).

During sampling, a cover letter is drawn up, in which they note: type, name, location, address of the water source (surface reservoir, artesian borehole, mine well, capturing, water tap, water column); its brief description; the state of the weather at the time of sampling and during the previous 10 days; the reason and purpose of sampling (scheduled survey, unfavorable epidemic situation, complaints of the population about the deterioration of the organoleptic properties of water); the laboratory where the sample is sent; the necessary amount of research is noted (brief, complete sanitary-chemical analysis, bacteriological analysis, determination of pathogenic microorganisms); date and time of sampling; results of studies performed during sampling (temperature); who took the sample (surname, position, institution); signature of the official who took the sample.

Samples are delivered to the laboratory as quickly as possible. Bacteriological studies should be started within 2 hours after sampling or if stored in a refrigerator at a temperature of 1-8 ° C - no later than 6 hours. Physical and chemical analysis is carried out within 4 hours after sampling or if stored in a refrigerator at 1-8 ° C - no later than 48 hours. If it is impossible to conduct research within the specified timeframes, the samples should be preserved (except for samples for physical, organoleptic and bacteriological studies, as well as BOD determinations, which must be carried out within the above timeframes). Samples are preserved with a 25% solution of H 2 SO 4 at the rate of 2 ml per 1 liter of water or in another way, depending on the indicators to be determined.

It has been found that drinking water inadequate quality is an important factor development of intestinal infections, malignant neoplasms of the intestine. An excess of certain substances in water can lead to a variety of diseases.

People who are seriously interested in maintaining their health understand the importance of drinking water that is appropriate for state standards quality. At the same time, it is no secret to anyone that not only tap water, but even bottled water is not always suitable for drinking.

In order to determine the quality of bottled, tap, or any other water that may be potable, water can be sampled and sent to a laboratory. If you want to find out what kind of bottled water you can drink, or if you want to approach the choice of a water filter with a full understanding of the situation, the water content analysis chemical substances and bacterial contamination is simply necessary. This will allow you to determine exactly which filter needs to be installed on the faucet in order to make the water drinkable.

If you decide to take a tap water sample, in order for the result to be reliable, it is necessary to take samples in compliance with all the rules established by GOST.

Sampling procedure for chemical analysis

To take the analysis, we need a plastic container from under the water with a volume of 1.5-2 liters. It is worth mentioning right away that even a thoroughly washed bottle from other drinks (soda, juices, etc.) may contain traces of dyes, substances dissolved in water, stabilizers and other components on its walls, which can distort the analysis of water. For this reason, only water containers are used to collect water. alternative plastic bottle a glass container with a tightly screwed or push-to-close silicone or plastic (polyethylene) lid can become.

Water analysis should be carried out with disposable rubber gloves, which can be easily purchased at a pharmacy.

Turn on the water at the tap. Let the water drain for 10-15 minutes. Rinse the container with the same running water, then carefully pour water into the container, sending a stream along its wall so as to avoid bubbling. During sampling, be careful not to let the neck of the bottle come into contact with a faucet or sink.

Since oxygen is able to participate in many chemical reactions, if the intake is incorrect, a distortion of the real picture can occur. Pour water to the top, then squeeze the container from the sides so that the water spills out of the bottle a little. In this state, tightly screw the cap on the bottle. This manipulation will prevent air from entering under the bottle cap.

Wipe out the bottle.

Attach (or better, stick) a document containing the following information to the water sample:

the exact date and time the sample was taken;
the exact place where the water was taken;
where does the water come from (for example, from a faucet);

Additional information:

for example, how long water was passed before sampling;
the reason why the sample is sent to the laboratory: for example, the taste of water has changed, an unpleasant odor has appeared, etc.;
how the water was collected.

It is better if the water sample for chemical analysis will be delivered to the laboratory by specially trained personnel. The fact is that GOST gives precise recommendations regarding the transportation of water samples: containers must be packed in special containers that protect containers with water from mechanical shocks and the effects of phenomena. environment. If this is not possible, you can deliver a bottle of water to the laboratory yourself. In this case, until the moment of transportation, it is necessary to place the container in a cool, dark place (a regular refrigerator will do). Sample analysis must be carried out no later than 6 o'clock after picking it up.

Similarly, water is taken for chemical analysis from a well or well, with the only difference that water from a well or well must first be taken using a clean container (bucket and other) and only then poured into a bottle.

Before opening the bottle, rinse the outside of the bottle with well water, then unscrew the cap and fill the container to the brim. Squeeze the sides of the bottle so that the water completely fills the neck of the bottle to the brim, then screw the cap tightly. Complete supporting documents.

Sampling procedure for bacteriological analysis

For sampling for microbiological analysis, it is better to use special sterile bags. GOST water sampling says that water containers, as well as lids or plugs that close the container, must withstand high temperatures. For this reason, water cannot be delivered in a regular plastic bottle.

If the package is not available, you can use an ordinary glass bottle or jar with a volume of more than 0.5 liters with a tightly screwed or push-to-close cap made of polyethylene, silicone, rubber. Do not use metal caps, as it can be toxic to microorganisms contained in the water, thereby distorting the sample. glass container and the lid must be thoroughly washed and sterilized by boiling or steam before sampling.

Before sampling, it is necessary to burn the water tap with an alcohol torch and wipe it with 96% alcohol. After that, it is necessary to skip the water for 10-15 minutes, completely turning the valve (opening the tap "at full power"). To prevent bacteria from the skin of the hands from getting into a sterile bag or other container, it is better to use sterile rubber gloves (sold at any pharmacy). Pour water into a sterile container with a volume of at least 0.5 liters (preferably 1.5-2 liters), avoiding touching the neck of the tap bottle or sink.

If you are using a special bag (you can take it in advance from the laboratory where the analysis will be carried out), tear off its upper part along the perforated line immediately before taking the sample, then open it by holding the special plastic holders (“ears” attached to the edges of the bag). ).

Open the container of water to be tested, or pour tap water into the bag up to the white line. After that, close the bag by squeezing the unoccupied upper part between the index and thumb fingers and moving your hands from the center to the top edge of the bag: in this way you will remove air from the bag and close it. Wrap the end of the bag free from water into a tube, then tie the ends together. Check if water is leaking. In accordance with GOST, water for microbiological research must be taken for analysis within 2 hours after its collection, in extreme cases - during 6 o'clock. Until the container is transferred to the laboratory, store it in a dark place at a temperature of 2-8 0 С (for example, in a refrigerator). It is necessary to transport the sample in a special container, in which it is possible to maintain a temperature of +2+8 0 С during the whole trip. In addition, during transportation, containers with water should not be exposed to sunlight or mechanical stress. If the container has a lid or stopper, water must not be allowed to come into contact with them so that microbial contamination of the water does not occur.

The container must be accompanied by an accompanying document. It must indicate the following:

the exact date;
time;
sampling location;
How was water sampled for analysis?
What is the purpose of the sample being tested?

If necessary, provide additional information.

Subject to all the requirements for taking a water sample for research, you will receive a reliable result within 1-3 days, if we are talking about chemical analysis of water, and within (maximum) 7-10 days - when conducting a test for microbiological contamination. As a rule, at the end of the study, laboratories issue an analysis protocol with detailed calculations on the content of certain substances or microorganisms.

Rice. 16.1. Thermometer for measuring water temperature in reservoirs, wells (a), bathometers for taking water samples for analysis (b).

For sampling water from flowing reservoirs (river, stream), a bathometer with a stabilizer was designed, which directs the neck of the vessel against the current.

A water sample from a water tap or equipped capturing is taken:

for bacteriological analysis, after preliminary burning of the outlet of the tap or capturing with an alcohol torch, draining water from the tap for at least 10 minutes, into a sterile bottle with a capacity of 0.5 l, with a cotton-gauze stopper, wrapped on top with a paper cap. In order not to soak the cotton-gauze stopper, the bottle is filled approximately three-quarters so that 5-6 cm of air space remains under the stopper. Dishes with a cotton-gauze stopper are sterilized in advance in an oven at 160 0 C for an hour;

for a short sanitary-chemical analysis (organoleptic indicators, main indicators of the chemical composition and indicators of water pollution), up to one liter is taken into a chemically clean dish, after rinsing it with selected water (for a complete sanitary-chemical analysis, 3-5 liters of water are taken).

An accompanying form is attached to the selected sample, which indicates the address, type of water source where the sample is sent, the purpose of the analysis, the date and time of sampling, and the signature of the official who took this sample.

Sampling is an important part of water analysis. The reliability of the measurement results depends on how it will be performed. Errors resulting from incorrectly conducted sampling are usually not corrected in the future, and they can make all studies, even using the most accurate and expensive equipment, meaningless. That is why water sampling must be carried out flawlessly at all stages: from the selection of the sampling site and the preparation of dishes to the transfer of samples for analysis to the laboratory.

When taking water samples, in order to ensure their representativeness and prevent changes in the composition of the water taken for analysis from the moment of sampling to the start of work in the laboratory, it is important to follow all the rules and recommendations established in the regulatory documents. However, it must be borne in mind that almost every type of water has its own characteristics of this procedure. The conditions to be observed in sampling are so varied that it is impossible to give detailed recommendations for all cases in accordance with all requirements.

Instructions for sampling water from a well and distribution network:

A water sample for bacteriological and complete (or brief) chemical analysis shall be taken by the Customer in a specially prepared container, which is received in the Contractor's laboratory on the eve of sampling.

Water sampling

The first step is to take a sample for bacteriological analysis:

1. Sampling is carried out disinfected (for example, by treatment with ethyl alcohol or disinfectant wipes for personal use) immediately before sampling with hands or sterile gloves.
2. Fire the tap in a circular motion“kwacha” (cotton or gauze swab, fixed on a wire, moistened with alcohol). When firing, observe the safety precautions for working with combustible materials;

Note:

This procedure is necessary in order to minimize the ingress of microorganisms into the sample, which may appear in the water during the destruction of biofilms and resuspension (deposits of sediments in the pipeline system, including dead ends and joints of pipelines and their bends) with an increase in water flow and pressure fluctuations in the network.
1. Open the faucet, run water for 15 minutes
2. The container is opened immediately before sampling, removing the stopper together with a sterile cap (made of thick paper). The cork and the edges of the container must not touch foreign surfaces.
3. Without changing the water pressure, fill the container up to the “shoulders” (there should be a space between the cork and the water surface), while avoiding contact with the tap or the walls of the well.
4. After filling, the container is closed with a sterile cap and delivered to the laboratory.

5. The time between sampling and delivery of samples to the contractor's laboratory is not more than 2 hours (up to 6 hours is allowed if stored at t 2-4°C).

6. When transporting a sample for bacteriological analysis, do not allow the stopper to get wet.

7. Containers with samples must be clearly marked and accompanied by a document (sampling act) of water sampling indicating the place, date, time of sampling and other information required by the laboratory for the performer.

Not allowed!!!

- use a water sample intended for microbiological analysis to measure temperature or another indicator measured at the sampling site;

- rinse the sampling containers before sampling;

- during the selection, grab the “neck” with your hands;

- during sampling, aseptic conditions (clean hands or sterile gloves) and protection of samples from dust should be provided;

- burn the surface of the tap with a lighter;

- examine water samples in case of violation of the terms of delivery and improper transportation or storage;

The second step is to take a sample for a complete chemical analysis (brief chemical analysis):

Without closing the tap, fill the container prepared for the sample for a complete chemical analysis with water:

When performing various studies, several glass and polymer containers are selected so that the total sample volume is not less than the allowable one;

When sampling water for a brief chemical analysis, pre-rinse the containers 2-3 times with the water being sampled;

After filling, the container is closed with a cork and delivered to the laboratory.

Sample containers must be clearly marked and accompanied by a document (sampling act) of water sampling indicating the place, date, time of sampling and other information required by the contractor's laboratory.

Requirements for the conditions of transportation, storage of water samples for sanitary and chemical analysis

The container is placed inside the container (thermal bag), which prevents them from tipping over, contamination, spontaneous opening of plugs.

Sample storage conditions should exclude exposure to sunlight and elevated temperatures on water samples.

Do not store water samples together with other substances

The period of delivery of the sample to the laboratory should not exceed more than 24 hours from the moment the sample was taken in the container.

Violation of the requirements for the selection, transportation and storage of water samples can affect the quality and reliability of the results!!!

The quality of water in terms of bacteriological and sanitary-chemical indicators is regulated by the following documents:

Drinking water centralizedwater supply (water supply network, wells, columns) - SanPiN 2.1.4.1074-01;

Drinking water non-centralizedwater supply (springs, wells, wells for individual use) - SanPiN 2.1.4.1175-02.

Water sampling for bacteriological and sanitary-chemical analysis is carried out in accordance with the requirements:

Any type of water(wells, reservoirs, pools) - GOST 31861-2012 “Water. General requirements for sampling”, GOST 31942-2012. "Water. Sampling for microbiological analysis»