SEMI-QUANTITATIVE TEST FOR PARAQUAT IN PLASMA AND URINE

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SEMI-QUANTITATIVE TEST FOR PARAQUAT IN PLASMA AND
URINE Syngenta Crop Protection Basel
Switzerland
Test developed at Syngenta CTL United Kingdom by
Bruce Woollen
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WHAT SAMPLES ARE AVAILABLE ?

• Blood plasma is the preferred sample
• If only blood serum is available this can also be
  tested with limitations for interpretation of
  results (see slide 19)
• Urine samples are useful to confirm that a
  poisoning case involves paraquat

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DITHIONITE REDUCTION OF PARAQUAT
Paraquat is converted to a blue colour by sodium
dithionite
Sodium dithionite
alkali
PARAQUAT
PARAQUAT RADICAL ION (BLUE)
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SUMMARY OF THE TEST

• PART 1
• A pre-screen will detect high concentrations of
  paraquat in plasma and urine
• If Part 1 is negative
• PART 2
• A more sensitive blue band test will detect
  paraquat down to 0.1 µg/mL

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WHAT IS NEEDED FOR THE TEST ?
1M NaOH ( FOR URINE)
WATER
SYNGENTA TEST KIT
15 ML PLASTIC TUBE
5 ML OR 10 ML SYRINGE
PLASTIC MICROPIPETTE
CEREX SILICA CARTRIDGE
GLASS TUBES 1.2 ML
SYRINGE ADAPTOR
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PREPARATION OF DITHIONITE REAGENT
2 MINS
10 mL WATER
MIX
ALLOW TO SETTLE 2 mins
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Video clip preparation of dithionite
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PART 1 PRE-SCREEN IN PLASMA OR URINE
X 20 drops
approx 0.9 mL
MIX
PLASMA or URINE
DITHIONITE REAGENT
COMPARE COLOUR
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COLOUR CHART FOR PRE-SCREEN
0 3
10 30
100 µg/mL
The limit of detection for paraquat in plasma
and urine is about 2-3 µg/mL
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Video clip pre-screen
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RESULTS OF THE PRE-SCREEN

• If a blue colour is produced the concentration of
  paraquat is estimated from the chart and no
  further testing is done
• If a very faint blue colour or no blue colour is
  produced the blue band test is carried out
• Urine samples require an additional step before
  the blue band test

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URINE ONLY
PREPARATION OF URINE FOR THE BLUE BAND TEST
IF TESTING PLASMA PROCEED TO SLIDE NO 14
DISCARD PELLET

URINE 5 mL
1M NaOH 0.5 mL
CENTRIFUGE
MIX
10 MINS
URINE FOR TESTING
3000 RPM
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PART 2 BLUE BAND TEST FOR PARAQUAT IN PLASMA
OR URINE
DITHIONITE REAGENT
approx 1 mL
2 MINS
BLUE BAND
PLASMA or URINE
3 mL
1 mL WATER
COMPARE COLOUR
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COLOUR CHART FOR BLUE BAND INTENSITY
0 0.1 0.2
0.5
1 2 µg/mL
Chart is applicable to both plasma and urine
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Video clip of blue band test
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INTERPRETATION OF PLASMA PARAQUAT RESULTS
Proudfoot curve predictive line
Examples a) 1 µg/mL at 8h after ingestion
survival unlikely b) 0.1µg/mL at 12h
after ingestion survival likely
a
survival unlikely
b
survival likely
Proudfoot A T, Stewart M S, Levitt T and Widdop
B. Paraquat Poisoning significance of plasma
paraquat concentrations. Lancet 1 330 1979
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INTERPRETATION OF PLASMA PARAQUAT RESULTS
From Syngenta paraquat treatment booklet
Example 1 µg/mL at 8h after ingestion approximat
ely 30 chance of survival
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WARNING ABOUT SERUM
Plasma versus serum Paraquat concentrations
in plasma and serum are NOT equivalent (serum
concentrations are about 3 times lower than
plasma concentrations) Proudfoot and Syngenta
survival curves are based on plasma
concentrations of paraquat
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INTERPRETATION OF URINE PARAQUAT RESULTS
From Schermann data
Dark blue
Navy blue
Light blue
Pale blue
No blue Colour
Schermann,J.M, Houze P, Bismuth C and Bourdon R.
Prognostic value of Plasma and urine paraquat
concentration. Human Toxicology 6 91-93 1987
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LIST OF EQUIPMENT AND SUPPLIERS

• Paraquat test kit containing sodium bicarbonate
  and sodium dithionite (Syngenta)
• Glass tubes 40 x 6mm 1.2mL (NLG Scientific)
• Cerex silica cartridges 3mL 20mg Cat no 620-0203
  ( Crawford Scientific)
• Micropipettes Mini-Pastette LW4231 (Alpha
  Laboratories)
• Syringe adaptor 120-1101 (Argonaut Technologies)