What is the difference between TCLP, SPLP and ZHE?

Modified on: Fri, 21 Dec, 2018 at 9:36 AM

TCLP (Toxicity Characteristic Leachate Procedure) and SPLP (Synthetic Precipitate Leachate Procedure) are used to assess the leachability of semi-volatile organic and inorganic parameters. 

ZHE (Zero-Headspace Extraction) is used to assess the leachability of volatile analytes whenever analysis of volatiles in leachates (either TCLP or SPLP) are required. 

It is also important to understand that these methods represent sample preparation techniques and not analysis.

All three methods are used to characterize the quality of leachates for either solids or multiphased matrix samples and determine whether a material or waste is considered hazardous in nature or not (as compared to provincial waste management criteria).

The difference in classification potentially determines the receiving facility the waste is suitable for (i.e. between a hazardous waste processor and a typical landfill). Alternatively, the data may be used to determine measures to be put in place should soil be required to be temporarily stockpiled on a site.

The principal difference between TCLP and SPLP are;

1. Applicability to real-world scenarios.

2. The pH level at which the extraction is completed. 

Much of the analytical approach between these two methods is similar.  Once leached, the extract undergoes analysis for target compounds in the same fashion as other routine environmental samples would.

Procedure Comparison


Comparison   ElementToxicity   Charcteristic Leaching Procedure (TCLP)Synthetic   Preciptitate Leaching Procedure (SPLP)Zero-Headspace   Extraction (ZHE)
Reference MethodEPA   1311EPA   1312EPA   1311
ApplicabilityLandfilling conditions (acetic acid)Stockpiling (acid rain)Volatile   Compounds only (as applicable under either a TCLP or SPLP request)
Multiphase SamplesIf >0.5% solid, liquid is separated for use   at a later time (may be combined with final leachate for analysis;  If <0.5% solids, the liquid, after   filtration is considered the extract (or leachate).Solid   material only.
Extraction ratio100g of solid sample material + extraction   fluid (1:20)25g   of solid mater + extraction fluid (1:20)
Selection of Extraction Fluid5g   of sample material is mixed with DI water in a slury, if the pH of this   mixture is <5.0, then TCLP Fluid #1 (pH 4.93) is used; if the pH of the slury mixture is >5, then TCLP fluid #2 (pH2.88) is used.For   sample east of the Manitoba/Ontario border, SPLP fluid #1 (pH 4.2) is used,   for samples west of the boarder, SPLP Fluid #2 (pH 5.0) is used.If   the ZHE procedure is for a TCLP request, TCLP fluid #1 is used; For a SPLP request, SPLP   Fluid #3 (DI water) is used.
Duration of Extraction18 hours
Extract filtrationFiltration through a 0.7um glass fiber filter.Not   applicable to the ZHE method (avoids loss of target analytes).

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