semi-quantitative test for paraquat in plasma and urine syngenta crop protection basel
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
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)