Acidic herbicides and o-phenylphenol (both with hydrolysis) in orange

Attention:
It is essential to apply a hydrolysis step for this ring test. An analysis of the esters and the free acids only results in an underestimation of the spiked levels! The test samples MUST be analysed twice - with and without hydrolysis.

The residue definitions of acidic herbicides according to regulation (EC) No. 396/2005 include the esters, salts and conjugates of the acidic herbicides. The conjugates can contribute significantly to the total amount of the respective herbicides determined in routine samples. An alkaline hydrolysis step is applied to quantify residues of the conjugates in routine samples.

The residue definition of 2-phenylphenol (sum of 2-phenylphenol and its conjugates, expressed as 2-phenylphenol) includes the conjugates as well. Please be prepared to analyse the conjugates of 2-phenylphenol as well.

P2428-RT is designed to cover all aspects of the analysis of acidic herbicides and 2-phenylphenol, including the hydrolysis step in accordance with the residue definition.

For that purpose the test material is spiked with selection of

conjugates of acidic herbicides and 2-phenylphenol,
commercially available esters of acidic herbicides, and
free acids of acidic herbicides.

In order to ensure that the results are unambiguously, either the conjugate or the ester or the free acid is spiked for each of the selected herbicide. In case of one of the herbicides, the conjugate, an ester and the free acid is spiked to simulate the residue situation in routine samples. Acidic herbicides within the scope of the test are summarised below (see parameters).

The participants are asked to report the results with and without hydrolysis. The results after alkaline hydrolysis (sum of conjugates, esters and free acids) are considered for evaluation of the trueness of results.

The analytical data are assessed with respect to

the identification of the spiked acidic herbicides,
the comparability (z-score), and
the trueness (70 to 120% of the spiked level).

Parameters

Analytical results without hydrolysis

2-phenylphenol, 4-CPA (free acid), 2,4-D (free acid), 2,4-DB (free acid), 2,4-dichlorprop (free acid), 2,4,5-T (free acid), 2,4,5-TP (free acid), clopyralid (free acid), dicamba (free acid), fenoxaprop (free acid), fluazifop (free acid), fluroxypyr (free acid), haloxyfop (free acid), MCPA (free acid), MCPB (free acid), triclopyr (free acid)

Analytical results with hydrolysis

2-phenylphenol (sum), 4-CPA (sum), 2,4-D (sum), 2,4-DB (sum), 2,4-dichlorprop (sum), 2,4,5-T (sum), 2,4,5-TP (sum), clopyralid (sum), dicamba (sum), fenoxaprop (sum), fluazifop (sum), fluroxypyr (sum), haloxyfop (sum), MCPA (sum), MCPB (sum), triclopyr (sum)

Expected time schedule

Please register before:
15 December 2023

Dispatch of samples:
19 February 2024

Deadline for reporting results:
13 March 2024

Costs of P2428-RT

Ring test and material	Amount	Price per unit
Acidic herbicides and o-phenylphenol (both with hydrolysis) in orange	–	850 €
Test material Orange, homogenised, spiked with free acids, ester, and conjugates of acidic herbicides and conjugates of o-phenylphenol	100 g	included
Analytical results without hydrolysis Free acids and esters, o-phenylphenol.		included
Analytical results with hydrolysis Sum of free acids, esters and conjugates.		included
Blank material Orange, homogenised, unspiked	100 g	70 €

Note: PROOF-ACS reserves the right to cancel tests in case of less than ten participants.