ESTABLISHMENT OF PESTICIDE RESSDUE ANALYSIS LABORATORY

INTRODUCTION:

The term ‘pesticide’ is used for all toxic chemicals used as pest control agents. They have become very popular with progressive farmers interesting in obtaining high yields of crop. Large number of pesticides has been developed in recent years for the chemical control of diseases and pests which destroy crops and stored grain food grains worth millions of rupees every year. These substances may be sprayed as dust, granules or may be applied in the form of emulsions and suspensions. Pesticides are applied as insecticides, fungicides, rodenticides, acaricides, herbicides or fumigants.

The pesticide present on leaves, skin or any other surface right after application is called deposits. Sometimes deposits can be easily seen, as is with many dusts or wettable powder formulations. If pesticide deposits remain on the surface one day after application, it is called as residue. Food and Agriculture Organization (FAO) has defined pesticide residues as any specified substance in food, agriculture commodities, animal feed, soil or water, resulting from use of pesticides. The term includes any derivatives of pesticide such as conversion products, metabolites, reaction products and impurities that are of toxicological significance. The term pesticide residue thus includes residues from unknown and unavoidable source (e.g. environmental) as well as from known uses of pesticides.

Some pesticides leave little or no residues, and others leave residues for weeks, months or even years. Depending upon on manner and place pesticides are used, each pesticide will vary in duration it remains on the crop or on the surface. It is important to establish what residues, if any, remain on the crop after a given period of time. A long lasting residue may be desirable because pesticides are effective for a longer period of time and they need not be applied very often. However, long lasting residues on food sources pose health risk to consumers. The amounts of residues remaining on crop after harvest depends on how long before harvest pesticides were applied. The basic phases involved in pesticides residues study are: a) design of experiment, b) sampling, c) extraction residues from substrate, d) clean-up and e) detection and quantification of residues.

As different types of pesticides have to handled by a pesticide testing laboratory the organization and working of the laboratory have to be very carefully planned such that each one of the analysis is carried out in the minimum possible time at maximum efficiency, ad also without any clash with other analyses.  As land, materials and technical personnel are highly costly inputs, attempts have to be made to get the maximum return of all the inputs and also bring down the cost of each of the analysis to the minimum without loss of efficiency.

To achieve the above objectives, the various units within a laboratory have to be so arranged that the movement of personnel and materials are reduced to the minimum in each operation to enable the staff to conserve their energy and materials and at the same time work at the peak efficiency.  It these laboratories considerable amount of poisonous fumes accumulate and these will vitiate the analytical values of samples especially those containing low amounts of active ingredients and also pollute the atmosphere to the extent of proving to be a source of chronic hazard to the health of personnel working in the laboratory. Besides, in the present day open world of trade reliable pesticide residues data in high value agricultural commodities are essential for acceptable export to the advanced, importing countries. Any neglect in pesticide residues analysis of export food commodities can account for economic loss of millions of rupees when these consignments are detained for this non-tariff reason by the importing countries.

Taking all these in to consideration, the requirements of men and materials have been detailed in the subsequent pages for establishing a pesticides testing laboratory capable of handling at least 5000 samples a year.  The layout of the laboratory given below is only an outline incorporating all the above requirements discussed under each unit.  But these have to be modified suitably based on the floor space available, architectural get up of the building by itself and in relation to the background, architectural nature of adjoining buildings, landscape and also the tests of the public and at the same time indicating the nature and importance of the work carried under the roof of that building.

FLOOR PLAN

The minimum floor space required for a laboratory to handle 5,000 samples per year is around 520 square meters (5600 sq.ft.) and could be distributed as follows among the various units.

Under each unit, the purpose of each requirement has been detailed. As the nature of samples received for analysis vary in easy regions, no hard and fast rule regarding the requirements of each units can be made.  Hence the plans proposed here are only broad outlines of the requirements and have to be modified suitably to meet the local needs.

1. Pesticides receiving and preparation room:  As all the incoming samples are received and prepared for analysis this room has to be located as far as possible near the entrance of the building but at the same time preferably on the rear side as considerable amount of dust and dirt will be accumulating in that room every day and as such may not give a very pleasing appearance at all times to a visitor even if cleaned every day.  Further, the door of the entrance should be wide enough to permit the entry of a jeep with a trailer or other motor vehicles up to the room to deposit the samples inside.  The following may be provided in the room.

• Two built in racks of 3 m x 00.75 m x 1 m (10’ x 25’ x 3’) approximately and one rack of 1.5 m x 0.75 m x 0.45 m (5’ x 2.5’ x 11.5’ approximately) for keeping the incoming parcels.
• A minimum of 10 aluminum or plastic trays of 0.6 m square (approximately 2’ square) x 0.15 m height (6’ height) for sampling dusts, water dispersible powders etc.
• A steel almirah of 1.6 m x 1.15 m x 0.5 m (approximately 6’x 3.5’ x 1.5’) for keeping registers.
• A powerful exhaust fan of 0.3 m or 045 m sweep (15’ or 18’ approximately) to exhaust all the fumes.
• A wash basin for washing.
• Two trolleys (portable) for transporting samples from this room to the pesticide storage room.
• Sufficient furniture for the staff.

As parcels from various agencies are received, checked bottled if necessary and labeled here, it is preferable to separate the samples into 3 or 4 broad groups viz., chlorinated hydrocarbons, organophosphorus insecticides, weedicides, miscellaneous pesticides like dithiocarbamates, copper compounds etc., and assign them laboratory numbers within each group.  This will reduce the time in locating them later.  To hasten up this, further suitable labels may be prepared in different distinctive colour for each group and pasted on each sample with all relevant details.  Then the samples may be moved to the storage room and stored.

2) Pesticides store room (6 m x 3 m):- Samples received from the preparation room are stored in the storage cabinets from the preparation room are stored in the storage cabinets of 1.5 m x 1.35 m x 0.45 m.  Each cabinet can accommodate 300 samples at a time and 12 such cabinets can accommodate about 3,500 samples.  Though samples should not be kept pending for more than 3 months, adequate provision for storing should be made to meet the peak season rush.  A powerful exhaust fan should be provided in this room to remove the possible accumulation of fumes continuously.  As far as possible, water pipes, drains etc., should not be allowed to pass through this room as excess humidity, high temperature, moisture etc., would affect the quality of the pesticides during storage.

3)and 4) Chemical store room and apparatus store room (6 m x 3 m each):- In view of the large number of pesticides that have to be analyzed, considerable quantities of the required chemicals and apparatus and their spares have to be stocked will in advance.  Due to the inflammable nature of most of the solvents, the chemicals and apparatus have to be kept in separate store rooms.  Each store room has to be provided with glass paneled storage cabinets with provision for locking.

5) Still room (3 m x 3 m): - As considerable quantity of distilled water will be required for daily use, installation of a large distillation unit will be economical. Normally a still has a rating of 6 to 8 Kw and as such provision has to be made for power point for a compressor.  Or alternatively a demineraliser with a minimum rated capacity of 100 liters/hour may be installed in the still room.  A tank of at least 250 liters capacity may be provided in the room to give a continuous supply of water to the still or demineraliser.  Rakes of 2.5 x 0.78 m x 0.8 m and with three shelves may be provided in the still room for storing the distilled water.

6) Gas room (3 m x 3 m):- In this room, small gas plants to supply the required amount of gas to the laboratories may be installed. In case gas plants are not available, gas cylinders like Indane may be kept in this room and supply affected to other units of the laboratory through pipe lines.  There should be good air circulation in the room and quick exit for escape in case of fire or explosion.  Necessary provision of power plug with build –in safety devices should be made for working the gas plants. Petrol, solvent oil or other fuel that are used for the preparation of gas should be kept away from the gas plants.

7) to 11) Analytical laboratories (6m x 4.5 m each):- Each one of the laboratories should be provided with the following

• Two work tables of 1.5 m x 2.1 m x 1 m and one side table of 6 m x 0.75 m x 0.9 m for analysis.
• One sink of 0.5 m x 0.3 m x 0.15 m (inside dimensions) in the centre of each of the work table and two sinks of the same dimensions in the side table.
• Water taps with six outlets near the sink of each table.
• A two shelf rack of 2.1 m x 0.3 m x 0.6 m for each one of the work tables to be fitted in the centre.
• A wash assembly for washing the apparatus.
• At least 10 power plug points for each work table for connecting the electrical equipments like heaters, water bath, etc., and carrying out the analysis in batc
• One fume cupboard for carrying out the digestion
• A powerful exhaust for each one of the units to exhaust all the poisonous gases from the laboratory.

12) Analytical laboratory (Standard solutions) (6 m x 4.5 m):  In this laboratory a constant supply of standard solutions will be needed for each unit to carry out the analysis in a batch system.  Further, as the final results of analysis depend entirely on the strength of standard solutions preparation room which is similar to other analytical units except for the following:

• Only four power plugs are provided for the whole unit as not much work will be carried with electrical equipments
• On the side table, two racks shelves of 6 m x 0.6 m x 0.6 m for keeping the standard solutions should be provided.

13) Balanced room/ instrument room (6 m x 3 m each):- As the final results of analysis also depend upon the accuracy of the weight of samples taken, the effects of air currents, moisture etc., should be eliminated when weights are being taken.  While weighing in the single pan balances the effects of shade should be eliminated to avoid the possible errors in the venire reading.  Hence the following should be provided in the room as indicated -

• Permanent slabs of 60 cm width at 100 cm height all round the room.
• The top of the slabs should be covered with acid/ alkali proof, washable tiles or sheets.
• Power plug points at convenient distances, preferably at 60 cm distance from each other.
• A sampling table of 100 x 100 x 75 cm with acid and alkali proof top.
• Glare proof lighting arrangement
• A stabilizer to control the power fluctuations.
• A sink of 0.5 m x 0.3 m x 0.15 m (inside) at one corner of the room for washing the outside of liquid containers, hands etc.
• These rooms should be air-conditioned if possible.

14) Exhibition cum seminar room (7.5 m x 3 m):- As the laboratories are likely to be located near or in Agricultural Universities/ research station / district headquarters, number of visitors of different categories like graduate and undergraduate students, gramsevaks, extension officers, trainees in other related fields, representatives of pesticides firms, officials etc., are likely to visit the laboratory.  Taking each group or individual around the laboratory and explaining the activities every will cause considerable disturbance to the staff attending to the analytical work and also it may not be possible to explain fully all the activates will not be going on at the same time.  Hence, it is better to have a separate exhibition room projecting all the activities of the laboratory to meet the requirements of all categories of visitors.  The nature of exhibits and mode of representing them has to be based on the local needs and levels of visitors likely to visits the laboratory.  Further, sufficient number of extra plug points at convenient distances should be provided for illuminating the charts and other materials

Provision like chairs, boards, screens should be provided in this room so that monthly/ fortnightly scientific seminars, conferences in small groups can also be conducted periodically to acquaint every one of the laboratory as well as visitors on the activities of the laboratory.

15) to 18) Officer’s room, office room and staff room: Sufficient amount of furniture for the staff have to be provided in the above rooms for all the staff working in these rooms.

19) and 20) Toilet and Wash room: - In addition to the normal facilities that should exist in a toilet and wash room, provision has to be made for a powerful shower in the wash room to enable a person to get drenched completely in one or two minutes in case of emergency like explosions, spillage of acids or alkalis on the body of the workers during digestion of liquids, transfer of solutions etc., and other accidents likely to occur during the activities of the laboratory.

21) Dead stock sore room (6 m x 1.5m):- the packing material like wooden cases, empty bottles, packing materials received after clearing the contents should be stored in this room for disposal.  The above dead stock may be disposed off as per the accepted procedure of the department or the institution.

22) Overhead Water Storage Tanks: - As continuous supply of water with pressure isrequired for circulation in the condensers throughout the day in the laboratory, an overhead tank with at least 5,000 liters capacity should be provided.  This is absolutely essential in places where regular water supply is provided only during certain hours of the day.

ORGANIZATION OF WORK FOR ACHIEVING MAXIMUM EFFICIENCY

A pesticide testing laboratory must process, analyze and report at least 50 samples per month per analytical assistant, leaving ample allowances for holidays, leave for the staff mechanical breakdowns and routine laboratory maintenance and repairs.  If the work is not organized with meticulous attention to all the details some process or the other will lab behind resulting in a loss of efficiency.

LIST OF APPARATUS REQUIRED FOR A PESTICIDE TESTING LABORATORY:

IMPORTANT REAGENTS/CHEMICALS USED IN THE ANALYSIS

OF PESTICIDES:

Pesticides and Herbicide Standards:

Total cost:

Staff:

1. Soil chemist…………… 1

2. Laboratory assistant………..2

3. Senior assistant…………..1

3. Junior assistant………….2

4. Lab workers…………..4

Modern methods of pesticide residue analysis:

Today, Gas Chromatography (GC), High Performance Liquid Chromatography (HPLC) and ELISA are the most widely used classical methods of pesticide residue analysis in food commodities throughout the world.

Some of the new trends in pesticide residue analysis are –

Gas Liquid Chromatography-Mass Spectrometry (GLC-MS), High Performance Liquid Chromatography-Gas Chromatography (HPLC-GC), Liquid Chromatography- Mass Spectrometry (LC_MS), Tandem Mass Spectrometry (MS-MS) and Supercritical Fluid Chromatography (SFC) combined with GC, HPLC or MS.

However, the use of these techniques and instruments is largely depending upon the availability of the equipment in the particular laboratory. The laboratory described above, we can use any of these technique/equipment and also more than one technique/equipment and run the laboratory successfully.