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. WHAT SAMPLES ARE AVAILABLE ?. Blood plasma is the preferred sample

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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


What samples are available
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


DITHIONITE REDUCTION OF PARAQUAT

Paraquat is converted to a blue colour by sodium dithionite

Sodium

dithionite

alkali

PARAQUAT

PARAQUAT RADICAL ION (BLUE)


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


1M

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


Sachet B

1g

Na2S204

Sachet A

2g

NaHC03

PREPARATION OF DITHIONITE REAGENT

2 MINS

10 mL WATER

MIX

ALLOW TO SETTLE 2 mins



PART 1 : PRE-SCREEN IN PLASMA OR URINE

X 20 drops

approx 0.9 mL

MIX

PLASMA

or URINE

DITHIONITE REAGENT

COMPARE COLOUR


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



Results of the pre screen
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


1M

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


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


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



Plasma paraquat concentration µg/mL

5

3

a

1.0

0.7

0.5

0.3

b

0.1

0.07

0.05

4

8

2

12

14

6

10

20

22

16

18

24

Time after ingestion (hours)

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


INTERPRETATION OF PLASMA PARAQUAT RESULTS

From Syngenta paraquat treatment booklet

Example :

1 µg/mL at 8h after ingestion

approximately 30% chance of survival


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


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


List of equipment and suppliers
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)


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