ON

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PRESENTATION ON BEHALF OF

• Crop Care Federation of India (CCFI)
• CropLife India
• Pesticides Manafucturers and Formulators
  Association of India
• BY DR.L.C.ROHELA

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SAMPLING
For analytical results to have any validity or
meaningful purpose, the appropriate sampling
procedure be adopted in such a manner that the
inherent characteristics climate is
retained.   The person taking the sample should
be fully aware of the nature of the sample and
the sampling method.
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SYSTEM OF ANALYSIS
No matter how skilled the analyst or how
sophisticated the analytical technique used, if
the calibration of the system is in error, the
analytical results will always be wrong   B.
Brookman Lab. of Govt. Chem. UK   System of
analysis includes sample preparation for
weighing, weighing dilution, pipetting and
instruments involved. The system must be
documented displayed for reference to every
concerned analytical chemist. Standards are used
to calibrate instruments, e.g. pH meter, auto
titrators. KF titrator, spectroscopes,
chromatographs etc.
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CERTIFIED REFERENCE MATERIALS
The goal of any analytical measurement is to get
accurate, reliable and consistent results.
Conforming to correct sampling, correct weighing,
use of well maintained calibrated instruments,
qualified operators, validated test methods
procedure for validation are all left redundant
if the accurate standard or certified reference
material are not used in the analysis. CRM not
only ensure accuracy of a specific method but
also enables the laboratory specific user to
verify the performance of instrument, procedure
and operators at any time.
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ANALYTICAL METHOD
A laboratory applying a specific method should
have documentary evidence that the method has
been appropriately validated. A method needs to
be revalidated whenever the conditions of
analysis changes e.g. instruement with different
characteristics.  
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PARAMETERS FOR VALIDATION OF TEST METHODS

• Accuracy Recovery
• Precision
• Repeatability
• Intermediate Precision
• reproducibility
•  
• Linearity
• Range
• Limit of detection/Limit of quantification
• Specificity/Selectivity
• Robustness
•  

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Deviations
We understand that the basic principles as
discussed are being followed then the need arises
to answer the observation of facts such as
  1.Inter laboratory result variations of the
same batch .   2. Non adherence of correct /
incomplete protocols of test. ( Particularly not
mentioning the amendment no. referred).
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Earlier Suggestions Still Pending
1. To submit chromatograms with run parameter
along with the test report. 2. Wherever two or
more test methods have been prescribed, the test
report should clarify the method used. 3. BIS
specification describes a sequence of tests for a
particular product which describe its nature.
Some of these tests are supportive to the active
ingredient test e.g. det. of Zn Mn in Mancozeb
free MMA in Monocrotophos, free paranitrophenol
in methyl parathion, LOD in 2,4-D Sodium Salt,
free 2,4-D acid in 2,4-D Ethyl Ester.
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4.BIS specifications of several products are not
finalised e.g. GC method for Ethion, packaging
specification of ANA, GC method of 2,4-D Ethyl
Ester etc. These to be taken on priority. In
combination formulation of mancozeb Carbendazim
or other combination formulation the test report
should clarify the test procedure used. In this
formulation Carbendazim should be tested by HPLC
method.  5.The State Govt. should be asked to
carry out the detailed analysis of the
performance of the companies/firms. This is
essential because there is tendency amongst many
inspectors to draw a majority of samples only
from good manufacturers so that they do not have
to face the problems of litigations subsequently.
We are thankful to the state of Rajasthan for
refining the methodology of drawing samples
.   6.Frequent interaction between
Industry-CIL-STPL to have transparency.  
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Case Study Product Analysis
  We share our experiences on specific products
which are commonly analysed by classical method
at all the laboratories where at certain points
if due precautions are not properly taken shall
lead to observance of variable results. If these
conditions of operations are not properly adhered
they may lead to become a source of error.
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Analysis of Bisdithiocarbamates
Mancozeb/Ziram/Thiram/Combinations
 Temperature of Sulphuric should be 600 C
min.   Do not use silicone rubber tubing as it
has tendency to absorb carbon disulphide which
will result in lower active ingredient.   Corning
glass beads of uniform size 4-5 mm be
used  Vacuum should be neither high nor low so
that carbondisulphide is neither transferred to
suction pump nor retained in the lead acetate
trap. This system contains 10 number of joints
which should be leak proof so that
carbondisulphide is not allowed to escape.
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Cold(200 C max.) water be circulated in the
condenser for complete reflux of water vapour.
Otherwise, due to uncondensed water, vapour in
round bottom, pressure is generated which causes
reaction mass to jump to lead acetate trap.   The
lead acetate trap temp. should be above 500
C   The methanol trap temp. should be maintained
below 100 C
The neutralizing of post-methyl xanthozanate with
30 acetic acid should be carried out in ice cold
water.   Iodine solution be standardized with
arsenic oxide sodium thiosulphate is secondary
std.  
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• Suphuric acid concentration should be 5N
  otherwise it will not result in complete
  digestion.
• Alcoholic potassium hydroxide solution must be
  such that the consumption of iodine solution by
  the neutralized potassium hydroxide (25ml)
  solution should not be more than 0.1ml. If it
  exceeds then the solubility of carbondisulphide
  becomes less, resulting in less content of
  Mancozeb.

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• DICOFOL 18.5 EC

• The reflex temperature and time must be
  sufficient.
• The reagent potassium hydroxide solution should
  be fresh as it becomes impure on long storage.
• Alcohol must be evaporated completely. Otherwise
  Dicofol content will be observed less.

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Methyl Parathion
uv-vis spectrophotometric method  Calibration
of the instrument is essential  Validated std. is
to be used  Sample weight to be taken as per IS
Specification. If sample wt. or std. wt. is more
absorbance will be very high. Hence, wt. to be
adjusted to get absorbance not more than
0.55  Repeated dilution to be made as defined in
IS.
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For det. of free p-nitrophenol, solvent ether is
used as solvent and p-nitrophenol extracted with
chilled sodium carbonate soln. This procedure has
been changed in various amendments. Extraction
has to be done very cautiously. The combined
extracted sod. carbonate soln. be diluted with
distt. water and temp. compensated and volume
made upto mark and then take absorbance at 400
nm.   For methyl parathion, blank is taken as
distt. water and for free p-nitro phenol blank is
taken as 1 sod. carbonate soln. which is diluted
as per the dilution carried out during
extraction.  
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Titration method   The titration has to be
performed at 00 100 C under mechanical stirrer
as rapidly as possible. Free para-nitrophenol
is to be extracted very carefully and slowly with
10 sod. bicarbonate without allowing emulsion
formation. Every time while extraction with 10
sodium bicarbonate anhydrous sodium sulphate must
be added.
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Distt. of benzene must be done carefully without
allowing charring or foaming taking
place.   Cooling must be done with clean good
quality ice.   Since the titration is done
rapidly if the end point taken after 4 drop near
the end point it is generally over stepped which
will give higher results. In such case the
analysis must be repeated and caution must be
taken at the end point. In such cases it is
advisable to conduct analysis in two sets
simultaneously.
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2,4-D Sodium Salt Tech. /Ethyl Ester EC
Free 2,4-D Acid should be extracted with 4 x 40
ml chilled diethyl ether   Washing of ether phase
be carried out with chilled distilled water. For
phase separation sufficient time be given or
otherwise sodium sulphate be added.   Amount of
ethanol to be added in such a manner that the
ether ethanol ratio is 11 and ether does not
get separated.  
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For determination of 2,4-D Ethyl Ester content in
EC formulation the free 2,4-D acid should be
substracted from total extractable 2,4-D content
and then multiplication factor of 249/221 be
applied. In the BIS specification though it is
mentioned in the principle but missing in
calculation. In 2,4-D Sodium Salt Tech. while
determining acid content the sample has to be
dissolved in hot distilled water at 90-950C to
facilitate complete dissolution. Confirm
complete splitting of the sample by adding little
more hydrochloric acid to the aqueous layer till
no more white precipitate occurs.  
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Monocrotophos 36 SL
MMA is highly hygroscopic and hence must not be
stored/used in humid conditions. Avoid repeated
opening of the bottle.   Sodium nitrite solution
should be freshly prepared.   Ferric chloride
solution must be filtered before make up to the
mark.   Neutralisation with 1 N nitric acid
should be carried out by maintaining temp. 250C.
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Weight of the sample be adjusted such that the
optical density is not more than 0.5 while
determining monocrotophos content and not more
than 0.7 while determining free MMA. BIS
specifications mentions 8 gms. of monocrotophos
36 SL to be taken for the determination of
monocorotophos content which gives high optical
density and hence weight be adjusted to 4 gms. or
dilution be made accordingly.   Throughout the
analysis temp. 255 should be maintained.   Methan
ol should be of spectroscopic grade and free from
aldehydes.  
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• TRIACONTANOL 0.1 EW

The determination of Triacontanol in its EW
formulation was not giving correct results of
active ingredients due to incomplete extraction
of active ingredients in petroleum ether and
without evaporating water of the formulations
sample. This has been achieved by first
evaporating water in rotatory evaporator and then
making solutions in chloroform. This method has
been validated and demonstrated in CIL.
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We all understand that Pesticide Analysis
requires systematic and sophisticated operations
and is not meant for raw hands, We appreciate
the efforts undertaken by most of the
laboratories by streamlining their process of
analytical operations but still nevertheless
upgradation and improvements are required at
certain places probably may be because of man
power transfers and extension persons on
deputation which can be further improved by more
active participation in inter laboratory results
comparisons.
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THANKS
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