EPA-OW/OST: 376.3: Acid Volatile Sulfide (AVS) in Sediment by Acidification and Gravimetry.

Summary
Analytes
Revision
Data and Sites

Official Method Name

Determination of Acid Volatile Sulfide and Simultaneously Extractable Metals in Sediment.

Current Revision

Draft, 1991

Media

SOILS/SEDIMENT

Instrumentation

Gravimetry

Method Subcategory

Inorganic

Method Source

EPA-OW/OST

Citation

USEPA, 1991, Draft analytical method for determination of acid volatile sulfide and selected simultaneously extractable metals in sediment: USEPA, Office of Science and Technology, EPA-821-R-91-100.

Brief Method Summary

Acid volatile sulfide is converted to hydrogen sulfide by acidification while at the same time selected metals are liberated. The hydrogen sulfide is then purged and the amount determined by gravimetry, colorimetry, or Ion-selective electrode method. Selected metals are membrane filtered and determined by atomic absorption or inductive coupled plasma spectrometry.

Scope and Application

This method describes procedures for the determination of acid volatile sulfide (AVS) and for selected metals that are solubilized during the acidification step (simultaneously extracted metal, SEM). As a precipitant of toxic heavy metals, sulfide is important in controlling the bioavailability of metals in anoxic sediments. Research has established that the relative amounts of SEM and AVS are important in the prediction of potential metal bioavailability; if the molar ratio of SEM for bivalent metals to AVS exceeds one, the toxic heavy metals in that sample are potentially bioavailable. This method uses that same conditions for release of both sulfide and metal from the sediment and thus provides a useful means of assessing the amount of metal associated with sulfide.

Applicable Concentration Range

> MDL

Interferences

Contact with oxygen must be avoided in all stages from sampling to analysis. Consequently, the samples and standards should be protected from air from the time of sampling through the analytical procedure. This can be achieved by deaerating and maintaining the samples under nitrogen or argon at all times.

Quality Control Requirements

Each laboratory using this method is required to operated a formal quality control program. The minimum requirement of this program consists of an initial demonstration of laboratory capability, and the analysis of laboratory reagent blanks, fortified blanks and fortified samples as a continuing check on performance. The laboratory is required to maintain performance records that define the quality of data thus generated.

Sample Handling

Samples should be cooled to 4 deg C as soon as possible after collection.

Maximum Holding Time

Holding time for samples should not exceed 14 days.

Relative Cost

$51 to $200

Sample Preparation Methods

This method has 7 analytes associated with it.

Analyte	Detection Level	Bias	Precision
Cadmium(7440-43-9) Cadmium Cd	N/A	N/A	N/A
Copper(7440-50-8) Copper Copper (metallic) Cu	N/A	N/A	N/A
Lead(7439-92-1) Lead Lead and compounds (inorganic) Lead and lead compounds Pb	N/A	N/A	N/A
Mercury(7439-97-6) Hg Hydrargyrum Liquid silver Mercury Mercury (inorganic) Quicksilver	N/A	N/A	N/A
Nickel(7440-02-0) Ni Nickel Nickel, soluble salts Raney Nickel (R)	N/A	N/A	N/A
Sulfide(18496-25-8) Sulfide	N/A	N/A	N/A
Zinc(7440-66-6) Zinc Zinc (fume or dust) Zinc and Compounds Zn	N/A	N/A	N/A

Precision Descriptor Notes:	The method detection limit (MDL) should be established for the analyte, using deionized water (blank) fortified at a concentration two to five time the estimated detection limit. To determine MDL values, take severn replicate aliquots of the fortified reagent water and process through the entire analytical method.
Detection Level Note:	The method detection limit should be established for the analyte, using deionized water fortified at a concentration two to five times the estimated detection limit. To determine MDL values, take seven replicates aliquots of the fortified reagent water and process through entire analytical method. MDL = t x s, where t = students' t value for a 99% confidence level and a standard deviation estimate with n-1 degrees of freedom (t = 3.14 for seven replicates), and s = standard deviation of the replicate analyses.

Precision Descriptor Notes:

The method detection limit (MDL) should be established for the analyte, using deionized water (blank) fortified at a concentration two to five time the estimated detection limit. To determine MDL values, take severn replicate aliquots of the fortified reagent water and process through the entire analytical method.

Detection Level Note:

The method detection limit should be established for the analyte, using deionized water fortified at a concentration two to five times the estimated detection limit. To determine MDL values, take seven replicates aliquots of the fortified reagent water and process through entire analytical method. MDL = t x s, where t = students' t value for a 99% confidence level and a standard deviation estimate with n-1 degrees of freedom (t = 3.14 for seven replicates), and s = standard deviation of the replicate analyses.

Revision	PDF/Link
Draft, 1991

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EPA-OW/OST: 376.3: Acid Volatile Sulfide (AVS) in Sediment by Acidification and Gravimetry.

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