1.0 Cleaning of sample Container
- For general purpose new glass container should be clean, with water and detergent to remove dust and packing material. They should be clean with chromic acid sulfuric acid mixture before being thoroughly rinsed with distilled water.
- It should be noted that detergents possibly containing phosphates, cannot be used if phosphates or surface active agent are to be determined, nor can chromic acid-sulphuric acid mixture be used if trace quantities of sulphate and chromium are to be determined.
- Polyethylene containers, in general, should be cleaned by filling with 1 Mol/l nitric acid or hydrochloric acid. Leaving for 1 to 2 days, followed by thorough rinsing with distilled or de-Ionized water.
- Glass containers should be cleaned with water and detergent, followed by thorough rinsing with distilled water. Then they should be rinsed with nitric acid (HNO3) followed by thorough rinsing with distilled water in order to remove heavy metals or chromate residues.
- A total of 0.1 ml of a 10 percent (m/m) solution of sodium Thiosulphate can be added, for every 125 ml of container capacity. before sterilization. This is to eliminate inhibition of bacteria by chlorine.
- Samples for microbiological analysis – The containers shall withstand a 160°C sterilization and shall not produce or release at this temperature any chemicals which would either inhibit biological activity, Induce mortality or encourage growth.
- When lower sterilization temperatures are used, polycarbonate and heat resistant polypropylene containers may be used. Caps or other stoppers shall withstand the same sterilization temperatures as the containers.
2.0 Sample Volume
A two-litre sample is normally sufficient for most physical and chemical analysis. However, the quantity may be varied depending upon the type of analysis, methods used etc.
3.0 Sample Preservation
Waste waters usually decompose rapidly at room temperature, therefore, certain tests. Namely, dissolved oxygen, sulphides, residual chlorine, nitrite, pH, etc., should be made or fixed at site. For certain other tests; preservatives should be added immediately to individual samples of the-same water or wastewater in different sampling bottles for each test. Summary of requirements for handling of samples is given in Table 1
4.0 Sampling Devices
Glass or polyethylene bottles are buoyant therefore; a sufficiently heavy bracket or holder should be used to overcome buoyancy. The bracket should be tied with a string and lowered into canal, river or well. The sampler is lowered to a desired depth and its stopper is removed by means of a jerk. When the bottle is full, it cannot be stoppered and should be pulled in open condition.
Table-1 Technique for the preservation of water sample
| Sr. No | Parameter to be studied | Type of Container | Preservation Technique | Minimum Volume | Maximum Recommended preservation time before Analysis | Remark |
| 1 | Acidity | P, G (B) | Refrigerate at 4°C | 100 | 24 hr. | Preferably analyzed at the spot |
| 2 | Alkalinity | P, G (B) | Refrigerate at 4°C | 100 | 24 hr. | Preferably analyzed at the spot |
| 3 | BOD | P, G (B) | Cooling between 2 To 5°C and store in the dark | 1000 | 24 hr. | _ |
| 4 | COD | P, G | Cooling between 2° and 5° and store in dark acidification to PH <2 Freezing to -20° | 100 | As soon as possible 2 days 1 Months | Acidification is particularly Recommended when the COD is due to presence of organic material |
| 5 | Fluoride | P | Add sodium hydroxide” adjust pH>12 | 500 | 24 hrs. | – |
| 6 | Chlorine, residual | P, G | – | 500 | Analysis immediately | Carry out on site |
| 7 | Colour | P, G (Brown) | – | 500 | – | – |
| 8 | Grease and oil | G wide with calibration | Acidification to PH<2 extraction on site where practicable | 1000 | 24 Hr. | It is recommend that immediately after sampling the extraction used in these method of analysis be added or extraction be carried on site |
| 9 | Iodide | G | Cooling to between 2 to 5°C Alkalization to pH 8 | 500 | 24 hrs to 1 month | Keep in dark |
| 10 | Metal Dissolved | P, G | – | 500 | – | Separate by Filteration with 0.45µm membrane filter immediately add reagent grade nitric acid to bring pH < 2 |
| 11 | Nitrogen Ammonia | P, G | Add conc. Sulphuric acid to bring pH<2 and refrigerate to 2 to 5°C | 500 | 24 hrs. | – |
| 12 | Nitrate | P, G | do | 100 | 24 Hrs. | For certain wastewater the sample cannot be preserved and It Is necessary to carry out analysis on site |
| 13 | Nitrite | P, G | Add mercuric chloride (40 mg/l). refrigerate to 2 to 5°C or freeze at -10°C | 100 | Analyse as soon as possible | – |
| 14 | Organic Matter | P, G | Add conc. Sulphuric acid to bring the pH<2 | 500 | Analyse as soon as possible | – |
| 15 | Dissolved Oxygen | P,G | – | 300 | Analyse as soon as possible | – |
| 16 | PH | P, G | Transportation at lower temp than initial temp | _ | 6 Hr. | Analysis preferably on site |
| 17 | Phenol | G | Inhibition of biochemical Oxidation By copper sulphate and acidification With phosphoric Acid or alkalinisation with sodium hydroxide to pH>11 | 500 | 24 hr | The preservation technique wlll depends on the method of analysis to be used or type of phenol |
| 18 | Phosphate dissolved in organic | G (A) | Filtration using 45µm membrane filter and sulphuric acid to bring PH<2 | 100 | Several Months | _ |
| 19 | Residue | P, G (B) | – | – | – | – |
| 20 | Salinity | G, Wax Seal | Use Wax Seal | 250 | Analyse Immediately | – |
| 21 | Silica | P | – | – | – | If Silica is high dilute at site with silica free water |
| 22 | Suspended and sedimentary matter | P, G | – | – | 24 Hr. | Should be carried out as soon as possible and preferably on site |
| 23 | Sulphate | P,G | Cooling to between 2°c to 5°c | 1 week | – | |
| 24 | Sulphide | P,G | Treatment with 2 ml of 1 mol per litre of zinc acetate and alkalinization with 2 ml of 1 mol per litre sodium hydroxide | 100 | 1 week | – |
| 25 | Sulphite | P,G | Fixing on site by addition of 1 ml of 2-5 percent (m/m) solution of EDTA per 100 ml of sample | – | 1 week | – |
| 26 | Temperature | – | – | – | – | Record immediately |
| 27 | Turbidity | P,G | Store in the dark up to 24 hr | – | – | Analyse as soon as possible |
5.0 Sampling Procedures
- Samples for physical and chemicals analysis should be collected in clean and dried bottle.
- Remove the cap from the bottle just prior to collect the sample.
- The sample side of the cap should not come in contact with any surface, including the finger or hands of the individual obtaining the samples.
- The cap may be kept on the top of a clean surface, topside against the surface.
- Rinse the sample bottle with the water to be sampled at least twice.
- Sample collection should be taken by using sampling device.
- Fill the bottle and remove the bottle from the sample stream and place the cap on the bottle as quickly as possible and ensure that no air bubble is entrapped.
- After sampling, the sample bottles should be carefully labelled to provide the following information.
1) Place of sampling,
2) Time and date of sampling,
3) Type of sampling and depth of sample.
4) Name of the s81npling staff, and
5) Purpose of sampling.
6.0 Transportation of Sample
The Individual wastes tend to decompose on keeping, which results in the change of composition at room temperature. The following measures should be adopted when transporting the samples from the place of sampling to the laboratory.
- The sample should be collected in leak-proof glass or plastic container;
- Sample should be transported in an ice box keeping the temperature around 4°C;
- Undue jerking of the samples should be avoided as this may result in coagulation of the Suspended matters;
- Immediately after reaching the destination, the samples should be transferred to refrigerator.
Reference
IS 3025 Part-1 -1987 RA 2019