Page:NIOSH Manual of Analytical Methods - 8315.pdf/4

This page needs to be proofread.

TRIAZINE HERBICIDES and THEIR METABOLITES: METHOD 8315, Issue 1, dated 15 March 2003 - page 4 of 6 34. The calibration standards are made the day of the analysis. Allow the stock solution and the internal sta ndard solution to w arm to room tem perature before perform ing any pipettin g. A ll the “pip ettin g” in this step is done using a 100 :L LC syringe. Prepare a diluted standard by adding 10 :L of the stock solution to 440 :L ethyl acetate to mak e a secondary solution. Prepare seven standards by first pipetting 10 :L of the internal standard solution into marked autosampler inserts/vials. Then add 10, 45, and 90 :L of the diluted standard to three vials and 10, 20, 50, and 90 :L of the stock solution to four of the vials. Make each vial contain 100 :L fin al volum e by adding the correct a m ounts of e thyl acetate. This will make standards that are about 0.48, 2.4, 4.8, 24, 48, 120, and 216 :m ol/L. Calculate the exact concentrations of each analyte in each standard from the stock solution concentrations. Insert these standards into the autosampler batch prepared in Step 32. 35. The two levels of quality control samples were made by adding 75 :L and 250 :L, of the stock solution to 250 mL of the pooled urine. Calculate the exact concentrations of each analyte in each quality control standard from the stock solution concentrations. Run enough QC samples so that they constitute ~10% of the batch and are equally divided between the two levels. Extract 5 mL of each QC (steps 3 through 32) and run with the samples. 36. Prepare calibration curves of Area std/Area IS vs conc std/conc IS for each of the six analytes.

MEASUREMENT: 37. Set gas chromatograph according to manufacturer’s recomm endations and to conditions on page 8315-1. 38. Set mass selective detector to the following SIM Param eters: Com pounds Dwell (ms) Start time* Ions Metabolites (5) & (6) 100 5.5 173, 158, 145, 172, 187 Parents (1) - (3) 100 14.1 201, 186, 200, 215, 214, 229 100 15.5 188 Phena nthrene-d 10 Cyanazine (4) 100 19.5 172, 225, 240

These start times m ay change as necessary, and should be checked regularly, especially after

replacing the guard column. A full-scan chromatogram should be performed on a standard to check the retention times and SIM windows. 39. Inject 1 :L ethyl acetate extract from step 32. 40. Measure the peak are as of the sam ples and internal stan dard. Divide the peak a reas of the sam ple by the peak area of the internal standard in the same chromatogram. The following ions are used unless the mass selective detector is capable of adding areas of more than one ion: Desisopropylatrazine 158 Desethylatrazine 172 Simazine 201 Atrazine 200 Propazine 214 Cyanazine 225

CALCULATIONS: 41. Determ ine the concen tration (C c) of the analytes in the extracts (in :mol/L) from the calibration curves. 42. The concen tration (C u) of the analytes in urine is calculated from the equation:

W here 50 is the concentration factorof going from 5 mL urine to 100 :L extracts, and 1000 is the factor for converting :mol/L to nmol/L. Note: These concentrations could be corrected for creatinine level or sample density if desired and if those values were obtained.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition