- Version 6 (Aug 2011, Document History, see page 37) Authors: M. Anastassiades; D. I. Kolberg; D. Mack; I. Sigalova; D. Roux; D.

Transcription

1 Quick Method for the Analysis of Residues of Highly Polar Pesticides in Foods of Plant Origin Involving Simultaneous Extraction with Methanol and LC-MS/MS Determination (QuPPe-Method) - Version 6 (Aug 211, Document History, see page 37) Authors: M. Anastassiades; D. I. Kolberg; D. Mack; I. Sigalova; D. Roux; D. Fügel 1. Scope and Short Description A method is described for the residue analysis of very polar, non-quechers-amenable, pesticides in foods of plant origin such as fruits (including dried fruits), vegetables, cereals and processed products thereof as well as honey. Residues are extracted from the test portion following water adjustment and the addition of acidified methanol. The mixture is centrifuged, filtered and directly analyzed by LC-MS/MS. Various options for the simultaneous LC-MS/MS analysis of different combinations of pesticides are provided. Quantification is in most cases performed with the help of isotopically labeled analogues of the target analytes, which are used as internal standards (IL-ISTDs). So far available, these IL-ISTDs are added directly to the test portion at the beginning of the procedure to compensate for any factors having an influence on the recovery-rates such as volume-deviations, analyte losses during the sample preparation as well as matrix-effects during measurement. 2. Apparatus and Consumables 2.1. Powerful sample processing equipment, e.g. Stephan UM 5 or Retsch Grindomix GM ml centrifuge tubes with screw caps, e.g.: a) reusable 5 ml Teflon centrifuge tubes with screw caps (e.g. Nalgene/Rochester, USA; Oak-ridge, article-no ) or b) disposable 5 ml centrifuge tubes (e.g. Sarstedt / Nümbrecht, Germany, 114x28 mm, PP, article-no ). 1 of 37

2 2.3. Automatic pipettes, suitable for handling volumes of 1 to 1 μl, 2 to 1 μl and 1 to 1 ml ml solvent-dispenser, for the acidified methanol (3.5) Centrifuge, suitable for the centrifuge tubes employed in the procedure (2.2) and capable of achieving > 25 g Syringe filters, e.g. Polyester filters.45 µm pore size Syringes e.g. 2 or 5 ml disposable polypropylene syringes suitable for Autosampler vials, suitable for LC auto-sampler, use plastic vials when Paraquat, Diquat, Streptomycin and Glyphosate are within the scope Volumetric flask with stoppers, for the preparation of stock and working solutions. E.g. 2 ml; 25 ml; 5 ml, 1 ml glass flasks. Use plastic flasks / stoppers for solutions containing Paraquat, Diquat, Streptomycin and Glyphosate LC-MS/MS instrumentation, equipped with ESI source and appropriate columns, see details in chapters till Chemicals Unless otherwise specified, use reagents of recognized analytical grade. Take every precaution to avoid possible contamination of water, solvents, sorbents, inorganic salts, etc Water (deionized) 3.2. Methanol (HPLC quality) 3.3. Acetonitrile (HPLC quality) 2 of 37

3 3.4. Formic acid (concentrated; > 95%) 3.5. Acidified methanol, pipette 1 ml formic acid (3.4) in a 1 ml volumetric flask and fill up to volume with methanol (3.2) Citric acid monohydrate (p.a.) 3.7. Dimethylamine, e.g. 4 % by Fluka (article-no. 3894) Ammonium formate (p.a.) 3.9. Pesticide Standards, of known purity Dry ice, technical grade can be used, but it should be periodically demonstrated not to contain any pesticides at relevant levels Pesticide Standards, of known purity Pesticide stock solutions, e.g. 1 mg/ml solutions of pesticide standards (3.9) in a water miscible solvent (e.g. water (3.1), methanol (3.2), acetonitrile (3.3) or mixtures thereof). See solvent-suggestions in Table 12. Use plastic vessels in the case of Paraquat, Diquat, Streptomycin and Glyphosate Pesticide working solutions / mixtures, prepared at appropriate concentrations by diluting pesticide stock solutions (3.12) of one or more pesticides with water-miscible solvents as required for the spiking of samples, in recovery experiments (5.4), or for the preparation of calibration standards (5.5). See suggestions in Table 12 in the Annex. Use plastic vessels in the case of Paraquat, Diquat, Streptomycin and Glyphosate Internal Standards (ISTDs), see details in Table of 37

4 3.15. ISTD Stock solutions, e.g. 1 mg/ml solutions of ISTDs (3.14) in a water miscible solvent (e.g. methanol, acetonitrile, water or mixtures thereof). For solvent-suggestions see Table 12. Use plastic vessels in the case of Paraquat-D6, Diquat-D4, Dihydrostreptomycin and Glyphosate (1,2-13 C 15 2 N) ISTD-working solution I (ISTD-WS I) for spiking samples prior to extraction, prepared at appropriate concentrations by diluting ISTD stock solutions (3.15) of one or more ISTDs with water-miscible solvents. Suggestions for solvents and concentrations are shown in Table 12 and Table 14. Use plastic vessels in the case of Paraquat-D6, Diquat-D4, Dihydrostreptomycin and Glyphosate (1,2-13 C 15 2 N) ISTD-working solution II (ISTD-WS II) for preparation of calibration standards, prepared at appropriate concentrations by diluting ISTD working solution I (3.16) with water-miscible solvents. Suggestions for solvents and concentrations are shown in Table 12 and Table 14. Use plastic vessels in the case of Paraquat-D6, Diquat-D4, Dihydrostreptomycin and Glyphosate (1,2-13 C 2 15 N), (see also subnote 3 in Table 1) LC-MS/MS mobile phases, see details in chapters till Disclaimer This method refers to several trade name products and instruments which are commercially available and suitable for the described procedure. This information is given for the convenience of the users of this method and does not constitute an endorsement by the EURL of the products named. The application of this method may involve hazardous materials, operations and equipment. It is the responsibility of the users of this method to establish appropriate safety and health practices prior to use. 5. Procedure 5.1. Sample preparation 4 of 37

5 To obtain representative test-portions from the laboratory sample, proceed as required by the respective regulations and guidelines. For fruits and vegetables cryogenic milling (e.g. using dry ice) is to be preferred to minimize degradations and improve homogeneity For dried fruits and similar commodities (< 3 % water content) the following procedure is proposed: Add 85 g of cold water to 5 g frozen dried fruits and homogenize the mixture using a strong mixer (2.1), if possible with addition of dry ice (3.1) g of this homogenate will correspond to 5 g sample Extraction / Centrifugation / Filtration Weigh a representative portion (m a ) of the sample homogenate (5.1) into a 5 ml centrifuge tube (2.2). In case of fresh fruits and vegetables as well as juices take 1 g ±.1 g of the homogenized sample. In case of dried fruits, dried vegetables, dried mushrooms take 5 g ±.5 g or 13.5 g ±.1 g of the re-hydrated and homogenized material according to (corresponding to 5 g sample). In case of cereals, dried pulses and honey also take 5 g ±.5 g. Notes: - Smaller sample portions may have to be used for extract-rich commodities, such as spices or fermented products, or commodities with very high water absorbing capacity not allowing proper extraction Add water (3.1) to a content of ca. 1 g in total according to the indications in Table 15 Notes: - No water adjustment is needed where re-hydrated commodities (5.1.1) are employed. - Where no ISTDs are used or where they are added after extract aliquotation, water adjustment is essential. Where the appropriate ISTDs are employed before any aliquotation has taken place water adjustment is less critical and can be skipped for commodities containing 8% water (see Table 15) Add 1 ml acidified methanol (3.5) and 5 µl of the ISTD-WS I (3.16) containing isotopically labeled analogues of one or more of the analytes of interest (added ISTD mass = m sample ISTD ). Notes: - The resulting extract volume, taking into account the natural water content of the sample and the water added in 5.2.2, should be ca. 2 ml (corresponds to ca..5 g sample per ml extract if 1 g sample is employed for extraction). - For screening purposes the ISTD can be alternatively added to the (e.g. 1 ml) sample extract aliquot that is transferred to the auto-sampler vial (see 5.2.8), assuming that 1 ml extract corresponds to exactly.5 g sample equivalents. This way the added amount of ISTD per sample can be drastically reduced (2-fold if added to 1 ml extract). The ISTD added at this step will compensate for matrix effects including retention-time shifts. The quantitative result should however be considered as tentative. For more accuracy samples should be re-analyzed with the ISTD being added in step Keep in mind that the final volume of the extract will deviate from 2 ml if water is not adjusted and additionally due to the ca. 2.5% volume contraction oc- 5 of 37

6 curring when methanol is mixed with water. The latter effect was considered in the water volumes listed in Table Close the tube and shake vigorously for 1 min by hand. Notes: - In case of dry products the 1 minute shaking is to be followed by a soaking period of 1 minutes and a subsequent second 1 minute vigorous shaking - Alternatively mechanical shaking at prolonged shaking times (e.g.5-2 minutes) may be employed for all sample types (no soaking period for dry commodities is necessary in this case) For Paraquat and Diquat the 1 minute shaking is followed by a thermal treatment of 15 minutes at 8 C in a water bath. Then shake again for 1 minute and wait for the sample to cool down to room temperature before centrifuging Centrifuge (e.g. for 5 min at >25 g) Using a syringe (2.7) filter an aliquot of the extract (e.g. 3 ml) through a syringe filter (2.6) into a sealable storage vessel. Notes: - In case of Paraquat, Diquat, Streptomycin or Glyphosate use plastic storage vessel or transfer an aliquot (e.g. 1 ml) directly into a plastic auto-sampler vial Transfer, as required, one or more aliquots (e.g. 1 ml each) of the filtered extract into autosampler vials (2.8) 5.3. Blank extracts Using suitable blank commodities (not containing any detectable residues of the analytes of interest), proceed sample preparation exactly as described in 5.2 but SKIP THE ADDITION OF ISTDs Recovery experiments Weigh an appropriate portion (see 5.2.1) of a blank commodity homogenate into a 5 ml centrifuge tube (2.2) and spike it with a suitable pesticide working solution (3.13 and Table 12). Spike directly to the matrix, prior to any water or solvent addition. Use small volumes of pesticide working solutions (e.g. 5-3 µl), to avoid too strong dilution. Conduct sample preparation exactly as described in Preparation of calibration standards Solvent-based calibration standards An exemplary pipetting scheme for the preparation of solvent-based calibration standards is shown in Table 1. 6 of 37

7 The calculation of the mass-fraction W R of the pesticide in the sample, when ISTD is used, is shown in Note: - Where solvent-based calibrations are used the use of IL-ISTDs for quantification is essential as the ISTD compensates for any matrix-related signal suppressions / enhancements Matrix matched calibration standards Transfer suitable aliquots of the blank extract (5.3) to auto-sampler vials and proceed as shown in Table 1. The calculation of the mass-fraction W R of the pesticide in the sample using matrix-matched calibration standards, with and without the use of IL-ISTD, is shown in and respectively. Table 1: Exemplary pipetting scheme for the preparation of calibration standards Calibration standards Solvent based (5.5.1) Matrix-matched (5.5.2) using ISTD 4 without ISTD 5 using ISTD 4 Calibration levels in µg pesticide /ml OR 6.5 in µg pesticide/ ISTDportion Blank extract (5.3) µl 9 µl 9 µl 85 µl 85 µl 85 µl 1:1 (v/v) mix of water (3.1) and acidified MeOH (3.5) 9 µl 85 µl 9 µl 5 µl - 5 µl 5 µl - 5 µl 1 µg/ml 5 µl 1 µl - 5 µl 1 µl - 5 µl 1 µl - Pesticide working solutions (3.13) 2 5 µg/ml µl µl µl ISTD-WS II (3.17) 1,3 5 µl 5 µl 5 µl µl 5 µl 5 µl Total volume 1 µl 1 µl 1 µl 1 µl 1 µl 1 µl 1 µl 1 µl 1 µl 1 One ISTD portion would correspond to the ISTD mass contained in 5 µl ISTD-WS II (the volume added to each calibration standard). 2 The concentration of the pesticide working solution(s) should be sufficiently high to avoid excessive dilution of the blank extract which would result in matrix effect deviations. 3 For calibration standards of 1 ml it is recommended to prepare the ISTD-WS II (3.17) by diluting 2-fold the ISTD-WS I (3.16). The same volume and pipette as in can then be used for the preparation of the calibration standards. 4 When employing IL-ISTDs matrix-matching and volume adjustments are of less importance as the ISTD compensates for any matrix-related signal suppressions / enhancements. Solvent-based calibrations can be used here.. Important in this case is a) the mass ratio of pesticide and ISTD in the respective calibration standards and b) the ratio between the ISTD mass added to the sample (5.2.3) and the ISTD mass added to the calibra- 7 of 37

8 tion standard(s) (5.5.1 and 5.5.2). For convenience this mass ratio should be kept constant throughout all calibration levels (e.g. at 2:1 when preparing calibration standards of 1 ml). 4 Where IL-ISTDs are not available/employed, matrix-matching via matrix-matched standards (Table 1) or the standard additions approach (5.5.3) are particularly important to compensate for matrix effects in measurement. In both cases the total volume of the sample extracts is assumed to be exactly 2mL. 6 The calibration level.5 corresponds to.1 mg pesticide /kg sample, when using 1 g test portions, or to.2 mg/kg sample when using 5 g test portions Standard-Additions-Approach Where no appropriate ISTDs are available the method of standard additions is a very effective approach for compensating matrix-induced enhancement or suppression phenomena. As this procedure involves a linear extrapolation it is mandatory that the relation between pesticide concentrations and the corresponding detection responses is linear throughout the relevant concentration range. Several aliquots of the final sample extract are fortified with increasing volumes of an appropriate pesticide working solution (3.13) as shown in Table 2. This procedure requires knowledge of the approximate residue level in the sample (w R(approx) ). This info is derived from a preliminary analysis. The calculation of the mass fraction of the pesticide in the sample w R is shown in Table 2: Exemplary pipetting scheme of a standard additions approach (for a sample extract containing.5 g sample equivalents per ml and an estimated residue level (w R(approx) )of,5 mg/kg Additions Vial 1 Vial 2 Vial 3 Vial 4 Volume of sample extract 5 µl (=.25 g sample) 5 µl (=.25 g sample) 5 µl (=.25 g sample) 5 µl (=.25 g sample) ISTD none none none none Added volume of pesticide working solution containing 5 µg/ml (3.13) m pest std add - 5 µl 1 µl 15 µl Resulting mass ( ) of pesticide.25 µg.5 µg.75 µg added to each vial Volume of solvent 15 µl 1 µl 5 µl - Final volume 65 µl 65 µl 65 µl 65 µl 8 of 37

9 5.6. LC-MS/MS Measurement Conditions Any suitable LC and MS/MS conditions may be used. Below you will find some exemplary instrument measurement conditions Method 1 (for Glyphosate & Co. ) Table 3: Proposed LC-MS/MS conditions for Ethephon, HEPA (ethephon metabolite), Glyphosat, AMPA (glyphosate metabolite), Glufosinate, MPPA (glufosinate metabolite), N-Acetylglufosinate (glufosinate metabolite) Instrument parameters Ionization mode Column/temperature (see also notes below) Conditions ESI neg Dionex IonPac AS 11 2 x 25 mm (P/N 4477); 4 C Pre-column Dionex IonPac AG11 2 x 5 mm (P/N 4479) Pre-filters Eluent A Water (3.1) Eluent B e.g. Supelco column saver 2. µm Filter (optional) 1 mm citric acid in water adjusted to ph 11 with dimethylamine (DMA) Note: You will need ca..5 ml DMA* solution for 5 ml 1 mm citric acid in water Make sure your eluent filters can handle alkaline solvents (see notes)!! Gradient %A Flow [ml/min] Time [min] Injection volume Calibration standards and levels Acquired mass transitions (m/z) 1-2 µl (Note: in case of analyzing only ethephon 5 µl may be enough -depending on the instrument) e.g..5 or.1 µg/istd-portion** + one level at the reporting limit Compound Glyphosate Glyphosate 13C215N (ISTD) AMPA AMPA 13C15N (ISTD) Ethephon Ethephon D4 (ISTD) HEPA HEPA D4 (ISTD) Glufosinate Glufosinate D3 (ISTD) N-AG N-AG D3 (ISTD) Mass Transitions (m/z) 168/63, 168/124, 168/15, 168/81 171/63 11/63, 11/79, 11/81 112/63 143/17, 143/79, 145/17 147/ /79, 125/95, 125/63 129/79 18/63, 18/136, 18/85, 18/95 183/63 222/63, 222/59, 222/ /63 MPPA 151/63, 151/17, 151/133 MPPA D3 (ISTD) 154/63 AMPA: Aminomethylphosphonic acid; MPPA: 3-Methylphosphinicopropionic acid; HEPA: 2-Hydroxyethylphosphonic acid (= ethephon-hydroxy), N-AG: N-Acetylglufosinate * The value of 1 ml DMA solution given in Version 4 of this document was an error (it should have referred to 1 L) ** One ISTD portion is the absolute ISTD-mass contained in the prepared calibration standard solution (see also Table 1). 9 of 37

10 Notes on LC-operation: Reconditioning: The column should be flushed from time to time (e.g. after injection of 5-1 extracts) 3 mm NaOH (e.g. for 1 hour at a flow rate of e.g..3 ml/min = ca 18 ml in total). The NaOH solution has to go directly into a waste bottle and SHOULDN T reach the MS ion source!. After reconditioning the column should be flushed with 3-1 ml of water to remove NaOH. Before starting analyzing samples, run the system 3-4 times with the full method for the column to re-equilibrate. Pre-filters: If pre-filters are used these should be regularly checked. In case pressure significantly increases they should be exchanged. For practical and convenience reasons pre-filters are exchanged when performing other maintenance operations such as reconditioning or pre-column exchange. Losses of Glyphosate, that could be clearly linked to interactions with a dirty pre-filter, have been once observed. Pre-column (guard column): The pre-column should be exchanged as soon as a clear deterioration of the separation performance (worsening of peak-shape) is noticed. If after pre-filter exchange (see above) the pressure does not come back to normal levels the frit of the pre-column should be exchanged. Column storage: Following normal operation, as described above, the columns can be stored directly after any normal sequence/run (full gradient). For columns that were stored for longer periods (e.g. >2 weeks) reconditioning, as descried above, is recommended. Columns flushed with NaOH should be flushed again with water (3-1 ml) before putting them aside for storage. LC-system specifications: As the ph of the mobile phase is quite high, it is recommendable to use alkali-compatible components, e.g. metal frits instead of silica frits in the Eluent B reservoir; borosilicate 3.3 bottles instead of glass bottles for eluent B; rotor-seals from alkali-persistent materials, such as PEEK (polyetherketone) or Tefzel, rather than Vespel. 1 of 37

11 Spargel mit.5 ug/is bw. ml in MeOH+1%AS - Glyphosat / 62.9 (Unknown) 167.9/62.9 amu - sample 25 of 34 from Validierun... Area: 2.12e+4 counts Height: 3.43e+3 cps RT: min Kartoffel mit.5 ug/is bw. ml in MeOH+1%AS - Glyphosat / 62.9 (Unknown) 167.9/62.9 amu - sample 27 of 34 from Validieru... Area: 2.6e+4 counts Height: 3.38e+3 cps RT: min Erdbeere mit.5 ug/is bw. ml in MeOH+1%AS - Glyphosat / 62.9 (Unknown) 167.9/62.9 amu - sample 28 of 34 from Validieru... Area: 2.37e+4 counts Height: 3.9e+3 cps RT: 9.61 min Spargel mit.5 ug/is bw. ml in MeOH+1%AS - AMPA 11. / 62.8 (Unknown) 11./62.8 amu - sample 25 of 34 from Validierung Et... Area: 3.99e+4 counts Height: 3.78e+3 cps RT: min Kartoffel mit.5 ug/is bw. ml in MeOH+1%AS - AMPA 11. / 62.8 (Unknown) 11./62.8 amu - sample 27 of 34 from Validierung E... Area: 4.11e+4 counts Height: 5.63e+3 cps RT: min Erdbeere mit.5 ug/is bw. ml in MeOH+1%AS - AMPA 11. / 62.8 (Unknown) 11./62.8 amu - sample 28 of 34 from Validierung E... Area: 8.87e+4 counts Height: 9.32e+3 cps RT: 7.86 min Spargel mit.5 ug/is bw. ml in MeOH+1%AS - Glufosinate 18. / 62.9 (Unknown) 18./62.9 amu - sample 25 of 34 from Validieru... Area: 4.42e+4 counts Height: 7.9e+3 cps RT: min Kartoffel mit.5 ug/is bw. ml in MeOH+1%AS - Glufosinate 18. / 62.9 (Unknown) 18./62.9 amu - sample 27 of 34 from Validier... Area: 4.74e+4 counts Height: 7.1e+3 cps RT: min Erdbeere mit.5 ug/is bw. ml in MeOH+1%AS - Glufosinate 18. / 62.9 (Unknown) 18./62.9 amu - sample 28 of 34 from Validier... Area: 8.3e+4 counts Height: 1.25e+4 cps RT: 7.32 min 1.2e4 1.1e4 1.e Spargel mit.5 ug/is bw. ml in MeOH+1%AS - MPPA 15.9 / 62.8 (Unknown) 15.9/62.8 amu - sample 25 of 34 from Validierung Et... Area: 1.27e+5 counts Height: 2.1e+4 cps RT: min 2.e4 1.9e4 1.8e4 1.7e4 1.6e4 1.5e4 1.4e4 1.3e4 1.2e4 1.1e4 1.e Kartoffel mit.5 ug/is bw. ml in MeOH+1%AS - MPPA 15.9 / 62.8 (Unknown) 15.9/62.8 amu - sample 27 of 34 from Validierung E Area: 2.e+5 counts Height: 2.62e+4 cps RT: min 2.6e4 2.4e4 2.2e4 2.e4 1.8e4 1.6e4 1.4e4 1.2e4 1.e Erdbeere mit.5 ug/is bw. ml in MeOH+1%AS - MPPA 15.9 / 62.8 (Unknown) 15.9/62.8 amu - sample 28 of 34 from Validierung Area: 1.25e+5 counts Height: 1.96e+4 cps RT: min 1.9e4 1.8e4 1.7e4 1.6e4 1.5e4 1.4e4 1.3e4 1.2e4 1.1e4 1.e Spargel mit.5 ug/is bw. ml in MeOH+1%AS - Ethephon / 16.9 (Unknown) 142.9/16.9 amu - sample 25 of 35 from Validieru... Area: 4.77e+4 counts Height: 6.63e+3 cps RT: 9.96 min Kartoffel mit.5 ug/is bw. ml in MeOH+1%AS - Ethephon / 16.9 (Unknown) 142.9/16.9 amu - sample 27 of 35 from Validier... Area: 4.78e+4 counts Height: 7.27e+3 cps RT: 9.35 min Erdbeere mit.5 ug/is bw. ml in MeOH+1%AS - Ethephon / 16.9 (Unknown) 142.9/16.9 amu - sample 28 of 35 from Validier... Area: 5.16e+4 counts Height: 7.93e+3 cps RT: 9.6 min EU Reference Laboratories for Residues of Pesticides Figure 1: Typical chromatograms of Glyphosate, AMPA, Glufosinate, MPPA and Ethephon Glyphosate AMPA Glufosinate MPPA Ethephon 168/63 11/63 18/63 15/63 143/17 In te n s ity, c ps I n te n s ity, c p s In te n sity, cp s In ten sity, cp s.1 ppm on asparagus In te n s it y, c p s In te nsity, cp s Inte nsity, cps In te n sity, cp s In te nsity, cp s.1 ppm on potato In te n s ity, c p s Intensity, cp s Inten sity, cps.1 ppm on strawberry CRL-SRM EPRW 28, June 1-5, Berlin Figure 2: Typical chromatograms of HEPA in real samples HEPA D4 (IS) 129/79 HEPA 125/95 HEPA 125/79 T Community Reference Laboratory for Pesticide R esidues using HEPA 125/63 Oat.34 ppm Figgs.12 ppm Pineapple.9 ppm 11 of 37

12 Method 2 (for Fosetyl and Maleic Hydrazide): Table 4: Proposed LC-MS/MS conditions for Fosetyl-Al, Maleic Hydrazide and Perchlorate Instrument parameters Ionization mode ESI neg Column/temperature Obelisc R 2.1 x 15 mm 5 µm 1 Å; (SIELC; OR ) Pre-filters e.g. Supelco column saver 2. µm Filter Pre-column Obelisc R 2.1 x 1mm 5 µm (SIELC; OR-21.G.51) Eluent A 5 mmol NH 4 -formate in water +.1 % formic acid use brown glass bottles Eluent B Acetonitrile Gradient %A Flow [ml/min] Time [min] Injection volume 5 µl Calibration standards and levels e.g..5 or.1 µg/istd portion*, + one level at the reporting limit Acquired mass transitions For maleic hydrazide (MH) an additional level at 1 or 2 µg/ml may be useful as well, due to high residue levels; consider that MH is typically only relevant for potatoes and crops of the leek family (onions etc.) Compound Mass Transitions (m/z) Fosetyl-Al (detected as foseyl) 19/81, 19/63 Fosetyl-Al D15 (ISTD) 114/82 (D5-fosetyl) Maleic hydrazide 111/82, 111/42, 111/55, 111/83 Maleic hydrazide D2 (ISTD) 113/42 Perchlorate 99/83, 11/85 Perchlorate 18 O 4 (ISTD) 17/89 * One ISTD portion is the absolute ISTD-mass contained in the prepared calibration standard solution (see also Table 1). Note: It should be kept in mind that standards of isotopically labeled pesticides may contain small amounts of native (unlabelled) compounds as impurities. Typically these impurities are at low levels, so that the added amounts of native-pesticides resulting from the addition of ISTDs are insignificant. In the case of maleic hydrazide (MH), however the amount of ISTD added is comparably high due to the low detection sensitivity achieved for this compound. Assuming native MH being contained as impurity in D2-MH at.25 % the resulting concentration of native MH following the addition of 2 µg D2-MH to 1 g sample will be at.5 mg /kg sample. This aspect is to be considered in the selection of Reporting Limits as well as when judging residue levels in samples having low MRLs (e.g. baby food) or organic food. 12 of 37

13 Wdf 1 Erdbeere,1 ppm,5g/is 1%AS in MeOH - Fosetyl-Al 19. / 81. (Unknown) 19./81. amu - sample 32 of 38 from Validieru... Area: 3.37e+4 counts Height: 6.3e+3 cps RT: 13.3 min ug/is in 1%AS in MeOH - Fosetyl-Al 19. / 81. (Unknown) 19./81. amu - sample 8 of 38 from Validierung_Malein_Fosetyl... Area: 6.63e+3 counts Height: 1.12e+3 cps RT: 13.5 min Maleinsaeure hydrazid,1 ug/is - Maleic hydrazid D2 113/42(IS) (Unknown) 113./41.9 amu - sample 4 of 12 from 8131Mc_Malein... Area: 5.84e+5 counts Height: 6.17e+4 cps RT: min 6.e4 5.5e4 5.e4 4.5e4 4.e4 3.5e4 3.e4 2.5e4 2.e4 1.5e4 1.e Zwiebel,5g/IS - Maleic hydrazid D2 113/42(IS) (Unknown) 113./41.9 amu - sample 8 of 12 from 8131Mc_Malein.wiff Area: 3.5e+5 counts Height: 3.21e+4 cps RT: min 3.2e4 3.e4 2.8e4 2.6e4 2.4e4 2.2e4 2.e4 1.8e4 1.6e4 1.4e4 1.2e4 1.e Zwiebel,5g/IS - Maleic hydrazid D2 113/42(IS) (Unknown) 113./41.9 amu - sample 8 of 11 from 8229_Malein.wiff Area: 1.46e+5 counts Height: 1.28e+4 cps RT: min 6.5e4 6.e4 5.5e4 5.e4 4.5e4 4.e4 3.5e4 3.e4 2.5e4 2.e4 1.5e4 1.e Zwiebel,5g/IS - Maleic hydrazid D2 113/42(IS) (Unknown) 113./41.9 amu - sample 7 of 12 from 8131Mc_Malein.wiff Area: 2.8e+5 counts Height: 2.58e+4 cps RT: 9.49 min 2.8e4 2.6e4 2.4e4 2.2e4 2.e4 1.8e4 1.6e4 1.4e4 1.2e4 1.e ug/is in 1%AS in MeOH - Fosetyl-Al 19. / 81. (Unknown) 19./81. amu - sample 11 of 38 from Validierung_Malein_Fosetyl... Area: 7.83e+4 counts Height: 1.35e+4 cps RT: 13.3 min 1.3e4 1.2e4 1.1e4 1.e Wdf 1 Erdbeere,1 ppm,5g/is 1%AS in MeOH - Fosetyl-Al 19. / 63. (Unknown) 19./63. amu - sample 32 of 38 from Validieru... Area: 1.18e+4 counts Height: 2.12e+3 cps RT: 13.3 min ug/is in 1%AS in MeOH - Fosetyl-Al 19. / 63. (Unknown) 19./63. amu - sample 8 of 38 from Validierung_Malein_Fosetyl... Area: 2.4e+3 counts Height: 4.32e+2 cps RT: 13.4 min Maleinsaeure hydrazid,1 ug/is - Maleic hydrazid 111 / 82 T T (Unknown) 111./81.8 amu - sample 4 of 12 from 8131Mc_Male Area: 2.88e+5 counts Height: 3.17e+4 cps RT: min 3.e4 2.8e4 2.6e4 2.4e4 2.2e4 2.e4 1.8e4 1.6e4 1.4e4 1.2e4 1.e Zwiebel,5g/IS - Maleic hydrazid 111 / 82 T T (Unknown) 111./81.8 amu - sample 8 of 12 from 8131Mc_Malein.wiff Area: 2.19e+3 counts Height: 3.2e+2 cps RT: min Zwiebel,5g/IS - Maleic hydrazid 111 / 82 T (Unknown) 111./81.8 amu - sample 8 of 11 from 8229_Malein.wiff Area: 6.32e+4 counts Height: 5.18e+3 cps RT: min Zwiebel,5g/IS - Maleic hydrazid 111 / 82 T T (Unknown) 111./81.8 amu - sample 7 of 12 from 8131Mc_Malein.wiff Area: 5.73e+6 counts Height: 5.32e+5 cps RT: min 5.e5 4.5e5 4.e5 3.5e5 3.e5 2.5e5 2.e5 1.5e5 1.e5 5.e ug/is in 1%AS in MeOH - Fosetyl-Al 19. / 63. (Unknown) 19./63. amu - sample 11 of 38 from Validierung_Malein_Fosetyl... Area: 2.65e+4 counts Height: 4.57e+3 cps RT: 13.3 min Maleinsaeure hydrazid,1 ug/is - Maleic hydrazid 111 / 55 (Unknown) 111./55. amu - sample 4 of 12 from 8131Mc_Malein.wiff Area: 1.23e+5 counts Height: 1.36e+4 cps RT: min 1.3e4 1.2e4 1.1e4 1.e Wdf 1 Erdbeere,1 ppm,5g/is 1%AS in MeOH - Fosetyl-Al D15(IS) (Unknown) 113.9/81.9 amu - sample 32 of 38 from Validierung_... Area: 8.88e+3 counts Height: 1.52e+3 cps RT: 13.1 min ug/is in 1%AS in MeOH - Fosetyl-Al D15(IS) (Unknown) 113.9/81.9 amu - sample 8 of 38 from Validierung_Malein_Fosetyl.wiff Area: 1.76e+4 counts Height: 2.88e+3 cps RT: 13.3 min Zwiebel,5g/IS - Maleic hydrazid 111 / 55 (Unknown) 111./55. amu - sample 8 of 12 from 8131Mc_Malein.wiff Area: 6.67e+2 counts Height: 1.57e+2 cps RT: min e4 4.e4 3.8e4 3.6e e4 3.2e4 3.e e4 2.6e4 2.4e4 2.2e4 2.e4 1.8e e4 1.4e4 1.2e4 1.e Zwiebel,5g/IS - Maleic hydrazid 111 / 55 (Unknown) 111./55. amu - sample 8 of 11 from 8229_Malein.wiff Area: 3.18e+4 counts Height: 2.42e+3 cps RT: min Zwiebel,5g/IS - Maleic hydrazid 111 / 55 (Unknown) 111./55. amu - sample 7 of 12 from 8131Mc_Malein.wiff Area: 2.5e+6 counts Height: 2.29e+5 cps RT: min 2.2e5 2.e5 1.8e5 1.6e5 1.4e5 1.2e5 1.e5 8.e4 6.e4 4.e4 2.e ug/is in 1%AS in MeOH - Fosetyl-Al D15(IS) (Unknown) 113.9/81.9 amu - sample 11 of 38 from Validierung_Malein_Fosetyl.wiff Area: 2.4e+4 counts Height: 4.e+3 cps RT: 13.1 min Maleinsaeure hydrazid,1 ug/is - Maleic hydrazid 111 / 42 (Unknown) 111./41.9 amu - sample 4 of 12 from 8131Mc_Malein.wiff Area: 3.74e+4 counts Height: 4.55e+3 cps RT: min Zwiebel,5g/IS - Maleic hydrazid 111 / 42 (Unknown) 111./41.9 amu - sample 8 of 12 from 8131Mc_Malein.wiff Area: 6.e+2 counts Height: 1.17e+2 cps RT: min Zwiebel,5g/IS - Maleic hydrazid 111 / 42 (Unknown) 111./41.9 amu - sample 8 of 11 from 8229_Malein.wiff Area: 1.8e+4 counts Height: 9.44e+2 cps RT: min Zwiebel,5g/IS - Maleic hydrazid 111 / 42 (Unknown) 111./41.9 amu - sample 7 of 12 from 8131Mc_Malein.wiff Area: 8.13e+5 counts Height: 7.41e+4 cps RT: min 7.e4 6.5e4 6.e4 5.5e4 5.e4 4.5e4 4.e4 3.5e4 3.e4 2.5e4 2.e4 1.5e4 1.e EU Reference Laboratories for Residues of Pesticides Figure 3: Typical chromatograms of Fosetyl-Al Fosetyl-Al 19 / 81 Fosetyl-Al 19 / 63 Fosetyl-Al D / 82 (ISTD) Recovery test on strawberry.1 mg/kg =.5 µg/ml Fosetyl-Al solvent calib..5 µg/ml =.1 mg/kg Fosetyl-Al solvent calib..5 µg/ml =.1 mg/kg Figure 4: Typical chromatograms of Maleic Hydrazide Maleic hydrazide solvent calib. =.5 µg/ml See note Onion sample.5 g/ml n.d. Maleic hydrazide D2 113/42 (ISTD) Maleic hydrazide 111 / 82 (target ion) Maleic hydrazide 111 / 55 Maleic hydrazide 111 / 42 Onion sample.5 g/ml ~.1 mg/kg Maleic hydrazide Onion sample.5 g/is ~ 4 mg/kg Maleic hydrazide 13 of 37

14 Method 3 (for Amitrole & Co) Table 5: Proposed LC-MS/MS conditions for Amitrole, Chlormequat, Mepiquat, Daminozide, ETU, PTU, Trimesium, Cyromazine Instrument parameters Conditions Ionisation mode ESI pos Column/temperature Obelisc R 2.1 x 15 mm 5 µm 1 Å (SIELC; OR ); 4 C Pre-column Obelisc R 2.1 x 1 mm 5 µm (SIELC; OR-21.G.51) Pre-filters e.g. Supelco column saver 2. µm Filter Eluent A 5 mmol NH 4 -formate in water Use brown glass bottles Eluent B 5 mmol NH 4 -formate Acetonitrile/Water 95 :5 (v/v) Gradient %A Flow [ml/min] Time [min] Injection volume 5 µl Calibration standards and levels e.g..5 or.1 µg/istd portion* + one level at the reporting limit Acquired mass transitions Compound Mass Transitions (m/z) Amitrole Amitrole 15 N (ISTD) Amitrole 15 N / 13 C (ISTD) Chlormequat Chlormequat D4 (ISTD) Mepiquat Mepiquat D3 (ISTD): Daminozide Daminozide D6 (ISTD): Cyromazine Cyromazine D4 (ISTD): ETU ETU D4 (ISTD): PTU PTU D6 (ISTD) Trimesium No ISTD currently available 85/57, 85/43 86/43 87/xx 122/58, 122/63, 124/58 126/58 114/98, 114/58 117/11 161/143, 161/11, 161/61, 161/ / /85, 167/125, 167/68 171/86 13/44, 13/6, 13/86 17/48 117/1, 117/58, 117/6 123/64 77/62, 77/47 - * One ISTD portion is the absolute ISTD-mass contained in the prepared calibration standard solution (see also Table 1). ETU: Ethylenethiourea; PTU: Propylenethiourea ; Trimesium=Trimethylsulfonium-cation Note: For Paraquat, Diquat and N,N-Dimethylhydrazine better run Method 4 (5.6.4) 14 of 37

15 Figure 6: Typical chromatograms of Amitrole, Chlormequat, Mepiquat, Daminozide, ETU, PTU and Cyromazine in Apple at.1 mg/kg Amitrol 85 /43 Mepiquat 114/98 Chlormequat 122/58 Daminozide 161 /143 Cyromazine 167/68 ETU 13/44 PTU 117/1 15 of 37

16 5.6.4.Method 4 (for Quats & Co ) Table 6: Proposed LC-MS/MS conditions Diquat, Paraquat, Chlormequat, Mepiquat, Daminozide N,N- Dimethylhydrazine, Cyromazine, Trimesium (counterion of Glyphosate) and Nereistoxin. Instrument parameters Ionisation mode Conditions ESI pos Column/temperature Obelisc R 2.1 x 15 mm 5 µm 1 Å (SIELC; OR ); 4 C Pre-filters e.g. Supelco column saver 2. µm Filter Pre-column Obelisc R 2.1 x 1 mm 5 µm (SIELC; OR-21.G.51) Eluent A Eluent B 2 mmol NH 4 -formate in water (adjust to ph 3 with formic acid), for this mix 1.8 ml formic acid (3.4) with 5 ml 2 mmol NH 4 -formate in water Use brown glass bottles! Acetonitrile Gradient %A Flow [ml/min] Time [min] Injection volume 1 µl Calibration standards and levels Acquired mass transitions e.g..5 or.1 µg/istd portion* + one level at the reporting limit (use plastic vials if Paraquat and Diquat are within your scope!) Compound Mass Transitions (m/z) Diquat** 184/128, 183/157, 184/156 Diquat D4 (ISTD): 188/16 Paraquat** 186/171, 171/77, 171/155 Paraquat D6 (ISTD): 192/174 Chlormequat 122/58, 122/63, 124/58 Chlormequat D4 (ISTD): 126/58 Mepiquat 114/98, 114/58 Mepiquat D3 (ISTD): 117/11 Daminozide 161/143, 161/11, 161/61, 161/115 Daminozide D6 (ISTD): 167/149 N,N-Dimethylhydrazine 61/44, 61/45 No ISTD currently available - Cyromazine 167/85, 167/125, 167/68 Cyromazine D4 (ISTD): 171/86 Trimesium 77/62, 77/47 No ISTD currently available - Nereistoxin 15/15, 15/61, 15/71 Nereistoxin D6 156/15 * One ISTD portion is the absolute ISTD-mass contained in the prepared calibration standard solution (see also Table 1). ** Diquat and Paraquat require special extraction conditions (see 5.2.5) Note: For ETU, PTU and Amitrole better run Method 3 (5.6.3) or Method 5 (5.6.5), for Morpholin, Diethanolamine (DEA) and Triethanolamine (TEA) better run Method 7 (5.6.7). As DEA converts to Morpholine in the ion source, chromatographic separation of these two is paramount. With Method 4 these two peaks do not sufficiently separate. 16 of 37

17 Figure 5: Typical chromatograms of Diquat, Paraquat, Chlormequat, Mepiquat, Daminozide, N,N- Dimethylhydrazine and Trimethylsulfonium-Cation (Trimesium) in Apple at.1 mg/kg Diquat 184/128 Diquat D4, 188/16 Paraquat 186/171 Paraquat D6, 192/174 Trimethylsulfonium 77/62 N,N-Dimethylhydrazine 61/44 Mepiquat 114/98 Mepiquat D3; 117/11 Chlormequat 122/58 Chlormequat D4; 126/58 Daminozid 161/143 Daminozid D6; 167/149 Nereistoxin D6 Nereistoxin 15/15 Nereistoxin 15/71 17 of 37

18 Method 5 (alternative method for Chlormequat and Mepiquat) Table 7: Proposed alternative LC-MS/MS conditions for Chlormequat and Mepiquat Instrument parameters Conditions Ionisation mode ESI pos Column/temperature MonoChrom MS 1x2 mm; 5 µm (Varian); at 4 C Eluent A 5 mmol/l NH 4 -acetate +.1% acetic acid Eluent B Acetonitrile Gradient %A Flow [ml/min] Time [min] Injection volume 5 µl Calibration standards and levels Acquired mass transitions e.g..5 or.1 µg/istd portion*+ one level at the reporting limit Compound Chlormequat Chlormequat D4 (ISTD): Mepiquat Mepiquat D3 (ISTD): ETU ETU D4 (ISTD): Mass Transitions (m/z) 122/58, 122/63, 124/58 126/58 114/98, 114/58 117/11 13/44, 13/6, 13/86 17/48 PTU 117/1, 117/58, 117/6 PTU D6 (ISTD) 123/64 * One ISTD portion is the absolute ISTD-mass contained in the prepared calibration standard solution (see also Table 1). For more information on method 5 please refer to the following document within the EURL homepage: 18 of 37

19 Method 6 (for Streptomycin and Kasugamycin) Table 8: Proposed LC-MS/MS conditions Streptomycin and Kasugamycin Instrument parameters Conditions Ionisation mode ESI pos Column Obelisc R 2.1 x 15 mm 5µm 1 Å (SIELC; OR ); 4 C Pre-filters e.g. Supelco column saver 2. µm Filter Pre-column Obelisc R 2.1 x 1 mm 5 µm (SIELC; OR-21.G.51) Eluent A.1% formic acid in water Eluent B.1% formic acid in acetonitrile Gradient %A Flow [ml/min] Time [min] Injection volume 5 µl Calibration standards and levels e.g..5 or.1 µg/istd portion+ one level at the reporting limit (use plastic vials if streptomycin is within your scope) Acquired mass transitions Compound Mass Transitions (m/z) Streptomycin 582/263, 582/246, 582/ 221 Dihydrostreptomycin (ISTD) 584/263 Kasugamycin 38/112, 38/2 No ISTD currently available - * One ISTD portion is the absolute ISTD-mass contained in the prepared calibration standard solution (see also Table 1). Figure 7: Typical chromatograms of Streptomycin and Kasugamycin Recovery test on Apple.1 mg/kg Recovery test on Honey.1 mg/kg Dihydrostreptomycin 584/263 (ISTD) Streptomycin 582/263 Kasugamycin 38/ of 37

20 5.6.7.Method 7 (for Morpholine, Diethanolamine and Triethanolamine) Table 9: Proposed LC-MS/MS conditions Morpholine, Diethanolamine and Triethanolamine Instrument parameters Conditions Ionisation mode ESI pos Column Dionex Acclaim Trinity P1 2.1 x 1 mm (3 μm) (P/N 71389); 4 C Pre-filters e.g. Supelco column saver 2. µm Filter Pre-column Dionex Acclaim Trinity P1 2.1 x 1 mm (3 μm) (P/N 71391) Eluent A 2 mmol NH 4 -formate in water (adjust to ph 4 with formic acid) Use brown glass bottles! Eluent B Acetonitrile Gradient %A Flow [ml/min] Time [min] Injection volume 5 µl Calibration standards and levels e.g..5 or.1 µg/istd portion+ one level at the reporting limit (use plastic vials if streptomycin is within your scope) Acquired mass transitions Compound Mass Transitions (m/z) Morpholine 88/7, 88/45, 88/44 Morpholine D8 (ISTD) 96/78 Diethanolamine (DEA) 16/88, 16/7, 16/45 Diethanolamine D4 (ISTD) 11/92 Triethanolamine (TEA) 15/132, 15/87, 15/7 Triethanolamine D12 (ISTD) 162/144 * One ISTD portion is the absolute ISTD-mass contained in the prepared calibration standard solution (see also Table 1). Morpholin, DEA and TEA are not pesticides, they are additive of waxes used to coat crops (citrus, apples and mangoes etc). They are included in this method for the sake of convenience and synergy. As these three compounds can be analyzed very sensitively 5-1-fold dilution of the extracts before injection is recommendable where possible, especially in absence of an ISTD requiring standard additions approach (5.5.3) Figure 8: Typical chromatograms of Morpholine, Diethanolamine and Triethanolamine in Apple extracts at.5 mg/kg (extract were diluted 5-fold before injection) Morpholine d8 Diethanolamine d4 Triethanolamine d15 Morpholine 88/7 T Diethanolamin 16/88 T Triethanolamine 15/132 T 2 of 37

21 5.7. Calibration and Calculations Using ISTD Where ISTD is added to the sample before any aliquotation: The following calculation approach requires that the ratio of the ISTD masses added to the test portions (5.2.3) and to the calibration standard(s) (5.5) (m sample cal ISTD / m mix ISTD ) is known and constant. By keeping the ISTD constant throughout the calibration levels the peak ratio PR cal mix cal (A mix pest / cal A mix cal ISTD ) of each calibration level can be plotted against the absolute mass of the pesticide m pest mix cal mix cal rather than the ratio m pest / m mix cal ISTD (the m mix ISTD is set as 1). The calibration graph (to be plotted for each pesticide separately) is described by the following formula: mix cal mix PR cal acal m pest + = b (1) cal The mass fraction (w R ) of a given pesticide in a given sample can be calculated as follows using the respective peak ratio of pesticide and internal standard obtained from the sample extract (PR sample = A Sample pest / A Sample ISTD ), the correction factor (m sample cal ISTD / m mix ISTD ) as well as the weight of the test portion (m a ). Sample Sample ( PR bcal) 1 mistd mg w = (2) R cal mix acal ma mistd kg Reasonably (but not necessarily) the calibration standards should be prepared in such a way that the ratio m sample cal ISTD / m mix ISTD equals 2 (the assumed volume ratio of sample extract versus calibration standard). The absolute masses of the ISTD-WS I and II do not need to be necessarily known (see also the notes of Table Where ISTD is added to an aliquot of the extract When adding the ISTD to an aliquot of the extract (e.g. 1 ml) theknowledge of the exact total volume of the sample extract becomes important. Water adjustment is thus essential and if it is done as described in and Table 15, the total volume can be asumed to be exactly 2 ml. In this case 1 ml sample extract will correspond to 1/2 th of the test portion (m a ). The mass of the ISTD to be added aliquot to an aliquot (m ISTD ) should be scaled according to the aliquot volume used (V aliquot ) with the ISTD mass ratio (m aliquot cal ISTD / m mix ISTD ) being important for the calculation. Reasonably (but not 21 of 37

22 necessarily) m aliquot ISTD should be derived using the following formula m aliquot ISTD = m sample ISTD x V aliquot /2 sample, with m ISTD being the ISTD mass that would have been added to the entire sample portion according to and Table 15. Following the above, the mass fraction (w R ) of a given pesticide in a given sample can be calculated as follows using the respective peak ratio of pesticide and internal standard obtained from the sample extract (PR sample = A sample pest / A sample ISTD ), the correction factor (m aliquot cal ISTD / m mix ISTD ) as well as the weight of the sample equivalents in the aliquot (m aliquot = m a x V aliquot /2). sample aliquot ( PR bcal) 1 mistd mg w = (3) R cal mix acal maliquot mistd kg Variables used Mass of pesticide in calibration mixture m µg cal mix pest Mass of pesticide in final extract Mass of internal standard in calibration mixture sample m pest cal mix m ISTD µg µg Mass of internal standard added to test portion (sample) Mass of internal standard added to aliquot of sample extract sample m µg ISTD aliquot m µg ISTD Volume of sample extract aliquot used ( and 5.5.3) to spike the ISTD or for standard additions aliquot V ml Mass of test portion m a g Mass of test portion represented in an aliquot m aliquot g Mass fraction of pesticide in the sample w R mg/kg Peak area of pesticide obtained from calibration standard (mixture) Peak area of ISTD obtained from calibration standard (mixture) Peak area of pesticide obtained from the injected extract Peak area of ISTD obtained from the injected extract cal mix A (counts) pest cal mix A (counts) ISTD sample A (counts) pest sample A (counts) ISTD Peak ratio of pesticide vs. ISTD obtained from calibration mixture PR cal mix (dimensionless) Peak ratio of pesticide vs. ISTD obtained from injected extract PR sample (dimensionless) Slope of calibration graph a cal (dimensionless) Bias of calibration graph (intercept) b cal (dimensionless) 22 of 37

23 Not using ISTD If no appropriate ISTDs are used it is of high importance to to properly compensate for matrix effects. For the compensation of matrix effects matrix-matched calibrations (5.5.2) and the standard additions approach (5.5.3) are recommended. In both cases the assumption is made that the total volume of the sample extract is exactly 2 ml. Adjustment of the water content (and extract volume) in the sample is thus paramount Calculations when employing matrix-matched calibration without ISTD The calibration graph (to be plotted for each pesticide separately) is described by the following formula: A a C + b cal mix pest = (1) cal cal mix pest cal The mass fraction (w R ) of a given pesticide in a given sample can be calculated as follows using the respective peak area of the pesticide obtained from the sample extract ( factor (V) as well as the weight of the test portion (m a ). Sample ( Apest bcal) 1 mg w R = Vend (2) acal ma kg sample A pest ) and a correction where V end is the total volume of the sample extract (2 ml). All other variables are listed in Calculations when employing the standard additions approach The standard additions approach is the method of choice where no appropriate IL-ISTD is available. This approach typically compensates matrix effect better than the matrix-matched calibrations (5.5.2). The mass fraction of the pesticide in the sample (w R ) is calculated via linear regression using a graphical presentation as shown in Figure 1. The Y-intercept of the calibration graph will indicate the pesticide mass contained in the non-fortified aliquot of the sample extract. 23 of 37

24 Figure 1 Internal calibration using the procedure of standard additions, schematically Key: Y Peak area of analyte std add X Added absolute mass of analyte m pest in µg x absolute amount of analyte in the sample extract (in µg) before standard addition (y = ) With x = y int ercept ( b) slope of the curve ( a) (µg) The calculation is performed as follows using the regression graph shown in Figure 1 w R = b a V al V m a mg kg where: b Y-intercept of the calibration graph of the analyte in question; a V end V al m a Slope of the calibration graph of the analyte in question (1/µg); Volume of sample extract (ml) (should be 2 ml) Volume of aliquots used for the standard additions approach (ml) Weight of initial sample portion (g) 24 of 37

25 6. Performance Data Exemplary results of recovery experiments (n=5) using matrix matched calibrations (for more information see method validation database at Table 1: Overview of exemplary Validation Data Pesticide Target Transition (m/z) Matrix Spiking Level [mg/kg] ISTD Mean Recovery [%] Amitrol 85/57 Cucumber.1 None, but matrix-matched AMPA 11/63 Wheat Flour.1 AMPA 13 C 15 N Chlormequat 122/58 Cherry.5 Chlormequat D Cyromazine 167/85 Pineapple.5 Cyromazine D Daminozide 161/143 Grape.5 Daminozide D Diethanolamine 16/88 Apple.5 87 Apple 1 Diethanolamine D4 93 Diquat 184/128 Potato.1 Diquat D4 11 2,4 Ethephon 143/17 Cherry.5 Ethephon D ETU 13/44 Carrot.1 ETU D Fosetyl-Al 19/81 Pineapple.5 Fosetyl-Al D Glufosinate 18/63 Cherry.5 Glufosinate D Glyphosate 168/63 Cherry.5 Glyphosate 13 C 15 2 N HEPA 125/79 Cherry.5 HEPA D Kasugamycin 38/112 Apple Honey.1.1 None, but matrix-matched calibration Maleic Hydrazide 111/82 Pineapple.5 Maleic Hydrazide D Mepiquat 114/98 Cherry.5 Mepiquat D Morpholin 88/7 Lime 1 Morpholin D8 16 MPPA 151/63 Cherry.5 MPPA D N-AG 222/63 Cherry.5 N-AG D Nereistoxin 15/15 Cuccumber.1 Nereistoxin D6 93 Paraquat 186/171 Barley.1 Paraquat D6 92 7, PTU 117/1 Carrot.1 None, but matrix-matched Streptomycin 582/263 Apple.1 Dihydrostreptomycin RSD [%] Triethanolamine 15/132 Apple Apple.5 1 Trimesium 77/62 Wheat Flour.1 Triethanolamine D12 None, but matrix-matched calibration of 37