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About Pesticides in Fruit

About this Testing

The current study protocol has been designed to support routine analytical laboratories testing pesticide residues in agricultural commodities. The PT will be used to assess the various matrices represented in the AOAC food composition triangle (Figure 1) over the course of five years. For the 2018/2019 financial year PTs will focus on pesticides in fruit, a high carbohydrate, low protein and fat matrix. These are Class A commodities, primarily of plant origin (Figure 2). The matrices selected for this year are oranges, apples and apricots.

Specific attention has been paid to tailoring the scheme to current export limits as well as maximum residue levels for the South African market. The target pesticide and commodities were selected to match the growth season within South Africa. Pesticides selected for analysis in this PT represents various chemical classes associated with the specific commodity selected. Thereby accommodating the routine analysis performed by the majority of laboratories at the time the proficiency test material is circulated.

 

    

 

Proficiency testing program scheme Provider

  • National Metrology Institute of South Africa

  • CSIR Scientia Campus

  • Pretoria

  • Meiring Naude Road

  • Brummeria

  • 0183

  • Private Bag X34

  • Lynnwood Ridge

  • Pretoria

  • 0040

  • South Africa

Scheme Co-ordinator

  • Dr Laura Quinn

  • Principle Scientist

  • Organic Analysis Section

  • Phone + 27 12 841 3359

  • E-mail: lquinn@nmisa.org 

Participation Fees and Charges
 

The cost of participation in one round of the PT scheme is R 6000.00 (0% VAT, please note that we are not a VAT registered company). This fee includes two test samples and a blank sample of 50 g each. Two participants may submit a result per laboratory using the sample provided. For more than two participants per laboratory an additional fee will be levied and additional material supplied. A discount will be offered for laboratories participating in all four of the PT rounds, please refer to Table 1. After conclusion of the PT round, a report will be issued. Upon registration for participation an official quotation will be provided. Please find registration form attached as an addendum to this document. Transport costs are not included in these fees please refer to the section “Test sample transport” below.

Table 1: Summary of participation fees

Participation

Participation Fees per Round

Single Round

R6 000.00

All three rounds

R5 000.00 (R15 000 in total)

 

Reports provided to participants

A report will be issued to each participant detailing their performance in the PT. The report will contain the following information: description of the material used and how it was prepared; verification of target values, a summary of participating laboratories analytical techniques and data evaluation. The PT value for the studies will be determined using participant consensus or a reference value issued by the NMISA depending on the number of participating laboratories. The NMISA reference value will be calculated using gravimetrically spiked values. A report detailing a participant's z-score will be issued within one week and a full PT report will be issued to each participating laboratory within one month of the submission deadline​.

​Statistical analysis
 

The participant data will be processed according to ISO 13528:2005 (Statistical methods for use in proficiency testing by interlaboratory comparisons). A z-score will be used to determine the individual laboratories performance based on the following equation:

The target standard deviation used to calculate the z-score will be based on the Horwitz performance model, where the maximum measurement result variation expected between laboratories is 22%.

Scheme Details

The agricultural commodities and pesticide residues selected for this proficiency testing scheme have been selected based on routinely tested seasonal commodities and their regulated pesticide residue limits respectively. Concentration levels range from below the regulated export limits to above the maximum residue limit for South Africa.

Test Samples

The test samples will consist of a homogenised raw fruit sludge that has been spiked with a known concentration of selected pesticides from the pesticide list described in Table 2. For each round a participant will be provided with 50 g of test sample. A portion of the un-spiked commodity will also be provided to be used as a blank control.

Table 2: List of possible matrix specific pesticides included within the 2018/2019 proficiency testing scheme.

Pesticide

Pesticide

Pesticide

2.4 D

Ethylene bisdithiocarbamates

Oxydementon-Methyl

Abamectin

Fenamiphos

Oxytetracycline

Acetamiprid

Fenazaquin

Parathion

Acrinathrin

Fenbuconazole

Phenthoate

Aldicarb

Fenbutatin oxide

Phosalone

Amitraz

Fenpropathrin

Phosphorus acid

Azinphos-methyl

Fenthion

Piperonyl Butoxide

Azoxystrobin

Fipronil

Pirirmicarb

Benomyl

Fluazifop-P-Butyl

Prochloraz

Cypermethrin

Flucorochloridone

Procymidone

Bitertanol

Formetanate

Profenofos

Bromucinazole

Fosetyl-A1

Propargite

Bromopropylate

Fosthiazate

Propineb

Buprofezine

Gamma-BHC

Propyzamide

Cadusafos

Gauzatine

Prothiofos

Captan/Captab

Gibberellic acid

Pyraclostrobin

Carbaryl

Haloxyfop

Pyrenthrins

Chinomethionat

Imazalil

Pyriproxyfen

Chlorphenapyr

Imidacloprid

Spinosad

Chlorpyrifos

Iprodione

Spirodiclofen

Chlorpyrifos

Isazophos

Tebuconazole

Copper Oxychloride

Kresoxim-Methyl

Teflubenzuron

Cyhalothrin

Mancozeb

Temephos

Cyhexatin

Maneb

Terbufos

Dementon-S-Methyl

Malathion

Tetradifon

Diazinon

Metalaxyl- M

Thiabendazole

Dichlofluanid

Methamidophos

Thiometon

Dicofol

Methidathion

Thiophanate-methyl

Difenoconazole

Methiocarb

Thiram

Dimethoate

Methomyl

Triazophos

Dimethyl-didecyl

Methyl- Parathion

Trichlopyr

Diothiocarbamates

Metiram

Trichlorfon

Dithianon

Mevinphos

Trifloxystrobin

Endosulfan

Omethoate

Triflumuron

Ethoprophos

Oryzalin

Zineb

 

Test sample transport

Samples will be packaged and transported in a manner to minimise deterioration of the sample in transit. Transport costs are calculated depending on the location of the participating laboratory and are therefore not included in the PT cost price. Upon registration, a quotation will be issued including transport costs. Local laboratories may collect the sample directly from the NMISA premises. For international laboratories, please note that any import or quarantine permits remains the responsibility of the participating laboratory, and must be submitted to the NMISA prior to the shipment date. Participants are accountable for all customs and import duties.

All PT material shall be delivered and collected at the participant’s own risk. The NMISA will not take responsibility for samples damaged during transport, although all due care will be exercised during packing to prevent this from occurring.

Methods of Analysis

Participants are requested to use the methods/ procedures used during routine sample analysis.

Information requested for reporting

An electronic result submission form will be sent to participants when samples are delivered/ collected. For each participant two results per pesticide per sample may be submitted.

The following information will be requested from participating laboratories:

  • Method validation information
  • Quality control measures implemented
  • Method of extraction used
  • Sample size analysed
  • Instrumentation specification
  • Analytical method information
  • Recoveries for method and if a correction for recoveries is applied
  • The method limit of detection and limit of quantification

Scheme Dates

Table 3: Pesticide in fruit PT scheme important dates

Matrix

Sample Distribution

Results submitted by

Report issued by

Oranges

02 July 2018

30 July 2018

30 August 2018

Apples

08 October 2018

08 November 2018

08 December 2018

Apricots

10 December 2018

14 January 2019

15 February 2019

Please note that the registration closing date is three(3) weeks before sample distribution

References

  1. F. Cordeiro. Statistical methods for use in proficiency testing (2009). Institute for Reference Materials and Measurements. JRC –EC
  2. M.M. Phillips, K.E. Sharpless and S.A. Wise. Standard reference materials for food analysis (2013). Analytical and Bioanalytical Chemistry, 405: 4325 – 4335
  3. Codex Alimentarius International Food Standards: Codex pesticides residues in food online database (July 2016).