AOAC Final Action Methods in 2018

( b ) Calculate the ratio of the analyte response to that of the ISTD. ( c ) Run a linear regression analysis using the ratio of each pesticide at five different levels with no weighting or 1/x weighting, where x = concentration. ( d ) Measure the peak area of each pesticide found in the sample and the peak area of corresponding ISTD. ( e ) Calculate the amount of each pesticide in the solution injected from the standard curve. ( f ) Calculate the amount of each pesticide present in the sample. Test results should be reported to two decimal places or four significant digits. References: J. AOAC Int . 94 , 1253(2011) J. AOAC Int . 96 , 432(2013) J. AOAC Int . 96 , 887(2013) J. AOAC Int . 98 , 130(2015) DOI: 10.5740/jaoacint.12-478 J. AOAC Int . 98 , 149(2015) J. AOAC Int . 98 , 1428(2015) DOI: 10.5740/jaoacint.15021 J. AOAC Int . 99 , 1049(2016) Final Action 2018 to include additional references and removal of “Qualitative” in G Posted: October 13, 2015 (First Action); December 2018 (Final Action

( 2 ) Measure the ion abundances for the qualifier ions for the detected pesticides and verify that they are within the expected limits. If the peaks match, the presence of the pesticide is confirmed. See Table 2014.09H . (b)  Quantitative calculations.— ( 1 ) Use instrument data processing software for GC-MS (SIM), GC-MS/MS, and/or LC-MS/MS to calculate a response ratio (measured abundance of pesticide/measured abundance of heptachlor epoxide for GC and chlorpyrifos methyl for LC) and construct a five-point matrix- matched calibration curve of response ratio versus concentration of pesticide in standard solution. ( 2 ) Using the regression data from the appropriate matrix- matched calibration curve, calculate the concentration of each pesticide found in the samples. ( 3 ) If a validated computer system is not being used for calculations, follow the steps below: ( a ) Measure the peak area of each respective standard level for each pesticide and the peak area of corresponding ISTD. Table 2014.09H. Recommended maximum permitted tolerances for relative ion intensities using a range of mass spectrometric techniques Relative intensity (% of base peak), % GC-MS (relative), % GC-MS/MS, LC-MS/MS (relative), % >50 ±10 ±20 >20–50 ±15 ±25 >10–20 ±20 ±30 ≤10 ±50 ±50

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