Modern Water: 73100: DDT in soils/sediment by immunoassay

Summary
Analytes
Revision
Data and Sites

Official Method Name

EnviroGard DDT in Soil Test Kit 73100 (SDI 1998) http://www.sdix.com/

Current Revision

1998

Media

SOILS/SEDIMENT

Instrumentation

Immunoassay

Method Subcategory

Organic

Method Source

Modern Water

Citation

Modern Water Inc. User Guides

Brief Method Summary

Inhibition immunoassay, with a colorimetric indicator for competitive binding of analyte and an enzyme-labeled conjugate to surface-immobilized antibodies. Colorimetric response is inversely related to the concentration of analyte in the sample or standard. Calibrated to determine sum of p,p'-DDT, p,p'-DDD and p,p'-DDE. Reagents are purchased in kits with manufacturers' instructions for sample preparation and analysis. Requirements: a supply of clean water and methanol, to extract soil and sediment samples, to dilute sample extracts, and to prepare standards; filtration equipment to remove particulates from water samples and soil extracts; an analytical balance, to accurately determine sample weights; a spectrometer, which accepts sample tubes (SDI EnviroGard), for analyses at visible wavelengths (450 nm primary; 600 or 650 nm reference); equipment to automate sample preparation for large numbers of samples (prefiltration, measurement of uL volumes, rinsing, agitation), so that contact times with reagents are controlled as required; computerized data acquisition and processing. Expendable supplies - approximately $16 per determination.

Scope and Application

Ambient and compliance monitoring. Can be used for Method 4042. Soil screening for DDT by immunoassay (EPA 1995).

Applicable Concentration Range

0.2 - 10 ug/g as sum of p,p'-DDT, p,p'-DDD, and p,p'-DDE

Interferences

Sensitivity > DDT: p,p'-DDD; DDA; chloropropylate; chlorobenzilate. Sensitivity < DDT: p,p'-DDE; dicofol; tetradifon. Sensitivity << DDT: o,p'-DDT; o,p'-DDE; o,p'-DDD;

Quality Control Requirements

Recommended for a kit allowing 20 semiquantitative determinations:

a. calibration with 3 standards (0.2, 1, 10 ug/g) and 1 blank

b. precision: 1 sample analyzed in duplicate (repeat)

c. accuracy: 1 matrix sample, spiked at mid-range with the target analyte.

d. validation: analysis of 1 positive and 1 negative sample by independent method for confirmation

Sample Handling

Samples are typically collected in glass containers with Teflon-lined caps. Samples are held in a refrigerator at 4 ^oC. Immunoassay reagents and kits are stored in the dark at 4 to 8 ^oC until use.
Soil and sediment samples need to be dried, weighed, and extracted (methanol; clean water). Soil extracts generally need to be centrifuged or prefiltered to 0.2 um. Quantitative analysis requires dilution of highly concentrated samples, until they are bracketed by standards in the linear response range. Aliquots of sample extracts and reagents are accurately measured (uL) and mixed for required times, following manufacturer's instructions for use of the materials purchased.

Maximum Holding Time

5 days at 4^oC until extraction and analysis

Relative Cost

Less than $50

Sample Preparation Methods

This method has 4 analytes associated with it.

Analyte	Detection Level	Bias	Precision	Pct False Positive	Pct False Negative	Spiking Level
4,4'-DDD(72-54-8) 1,1-Dichloro-2,2-bis(p-chlorophenyl)ethane 4,4'-DDD Benzene, 1,1'-(2,2-dichloroethylidene)bis[4-ch Benzene, 1,1'-(2,2-dichloroethylidene)bis[4-chloro- Dichloro-2,2-bis(p-chlorophenyl)ethane,1,1- Dichlorodiphenyldichloroethane Ethane, 1,1-dichloro-2,2-bis(p-chlorophenyl)- Rhothane TDE Tetrachlorodiphenylethane p,p'-DDD p,p'-Dichlorodiphenyl dichloroethane p,p'-TDE	0.040 ug/g	N/A	N/A	6	0	0.20 ug/g
4,4'-DDE(72-55-9) 1,1'-(-Dichloroethenylidene)bis(4-chlorobenzene) 4,4'-DDE 4,4'-DDE, DDT, DDD Benzene, 1,1'-(dichloroethenylidene)bis[4-chlo Benzene, 1,1'-(dichloroethenylidene)bis[4-chloro- Ethylene, 1,1-dichloro-2,2-bis(p-chlorophenyl)- bis(p-Chlorophenyl)-1,1-dichloroethylene,2,2- p,p'-DDE p,p'-Dichlorodiphenyldichloroethylene	0.040 ug/g	N/A	N/A	6	0	0.20 ug/g
Organochlorine pesticides(E-12851) Organochlorine pesticides Pesticides, organochlorine	N/A	N/A	N/A
p,p'-DDT(50-29-3) 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane 4,4'-DDT Benzene, 1,1'-(2,2,2-trichloroethylidene)bis[4-chloro- Chlorophenothane DDT Dichlorodiphenyltrichloroethane Ethane, 1,1,1-trichloro-2,2-bis(p-chlorophenyl)- bis(p-Chlorophenyl)-2,2,2-trichloroethane,1,1- p,p'-DDT p,p'-Dichlorodiphenyltrichloroethane	0.040 ug/g	N/A	N/A	6	0	0.20 ug/g

Precision Descriptor Notes:	Generally low recovery of DDT from soils in methanol extracts. Percent false positives and false negatives from EPA Method 4042 Soil screening for DDT by immunoassay (EPA 1995): 6% false + at 0.2 ug/g; 0% false - at 0.2 ug/g. NOTE: Measurements in ug/g as chlordane.
Detection Level Note:	spiked replicates: interpolation at 78% Bo, equal to 3 standard deviations from the mean of negative water samples

Revision	PDF/Link
1998

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Modern Water: 73100: DDT in soils/sediment by immunoassay

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