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

• 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

N+

N+

CH3CH3 C NN+

CH3CH3

DITHIONITE REDUCTION OF PARAQUAT

Sodium

dithionite

alkali

PARAQUAT PARAQUAT RADICAL ION

(BLUE)

Paraquat is converted to a blue colour by sodium dithionite

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

PLASTIC

MICROPIPETTESYRINGE ADAPTOR

15 ML PLASTIC TUBE

CEREX SILICA CARTRIDGE

WATER

WHAT IS NEEDED FOR THE TEST ?

1M NaOH( FOR URINE)

5 ML OR 10 ML SYRINGE

GLASS TUBES 1.2 ML

SYNGENTA TEST KIT

1M

10 mL WATER

2 MINS

ALLOW TO SETTLE 2 mins

MIX

Sac

het

B

1g

N

a2S

204

Sachet A

2g

NaH

C0

3

PREPARATION OF DITHIONITE REAGENT

Video clip preparation of dithionite

approx 0.9 mL

X 20 drops

PLASMA

or URINE

DITHIONITE REAGENT

MIX

PART 1 : PRE-SCREEN IN PLASMA OR URINE

COMPARE COLOUR

The limit of detection for paraquat in plasma and urine is about 2-3 µg/mL

0 3 10 30 100 µg/mL

COLOUR CHART FOR PRE-SCREEN

Video clip 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

IF TESTING PLASMA PROCEED

TO SLIDE NO 14

PREPARATION OF URINE FOR THE BLUE BAND TEST

URINE

5 mL

1M NaOH

0.5 mL

+

CENTRIFUGE MIX

URINE FOR TESTING

10 MINS

3000 RPM

URINE ONLY

DISCARD PELLET1M

PART 2 : BLUE BAND TEST FOR PARAQUAT IN PLASMA OR URINE

~ 3 mLPLASMA

or URINE

DITHIONITE REAGENT

2 MINS

~ 1 mL

WATER

BLUE

BAND

approx 1 mL

COMPARE COLOUR

0 0.1 0.2 0.5 1 2 µg/mL

COLOUR CHART FOR BLUE BAND INTENSITY

Chart is applicable to both plasma and urine

Video clip of blue band test

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

INTERPRETATION OF PLASMA PARAQUAT RESULTS

a

b

Proudfoot A T, Stewart M S, Levitt T and Widdop B. Paraquat Poisoning : significance of plasma paraquat concentrations. Lancet 1: 330 1979

a

b

0.3

0.5

0.7

1.0

0.05

0.07

0.1

3

5

2 4 6 8 10 12 14 16 18 2220 24

Pla

sma

para

quat

con

cent

ratio

n µ

g/m

L

Time after ingestion (hours)

survival unlikely

survival likely

From Syngenta paraquat treatment booklet

Example :

1 µg/mL at 8h after ingestion

approximately 30% chance of survival

INTERPRETATION OF PLASMA PARAQUAT RESULTS

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

No blue Colour

Pale blue

Light blue

Navy blue

Dark blue

From Schermann data

INTERPRETATION OF URINE PARAQUAT RESULTS

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

• 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)