Method 321.8: Determination of Bromate in Drinking Waters by Ion Chromatography Inductively Coupled Plasma-Mass Spectrometry

Original publisher: [Cincinnati, OH] : United States Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, [1997] OCLC Number: (OCoLC)65199958 Subject: Drinking water -- United States. Excerpt: ... 115 %, section 9.3.2 ) and monitoring the instrument drift standard injected with each sample. 9.3.5 Instrument Drift Standard-The analyst is expected to monitor the response from the instrument drift standard ( in each sample ) throughout the sample set being analyzed. The absolute response of any one drift standard must not deviate more than 70-130 % of the original response associated with the calibration blank. If deviations greater than these are observed, the reason for the drift should be investigated. Possible causes of drift may be a partially blocked sampling cone or a change in the tuning condition of the instrument. 9.4 Assessing Analyte Recovery and Data Quality 9.4.1 The chemical nature of the sample matrix can affect analyte recovery and the quality of the data. Taking separate aliquots from the sample for replicate and fortified analyses can in some cases assess the effect. Unless otherwise specified by the data user, laboratory or program, the following laboratory fortified matrix ( LFM ) procedure is required. 9.4.2 The laboratory must add a known amount of analyte to a minimum of 10 % of the routine samples. In each case the LFM aliquot must be a duplicate of the aliquot used for sample analysis. The added bromate concentration must be the same as that used in the laboratory fortified blank. Over time all routine sample sources should be fortified. 9.4.3 Calculate the percent recovery for bromate, corrected for background concentrations measured in the unfortified sample, and compare these values to the designated LFM recovery range of 70-130 %. Percent recovery may be calculated using the following equation: C-C s R = x 100 ) ) ) ) ) ) s where: R = percent recovery. C = fortified sample concen...