recovery and between 0% and 10% relative standard deviation.

Transcription

1 THE NEED FOR ANALYTICAL QUALITY CONTROL IN ORDER TO MEET EFFLUENT PERMIT REGULATIONS IN THE METAL FINISHING INDUSTRY JEFFREY GLASS LABORATORY MANAGER ENVIROPACT, INC. MIAMI DIVISION 479 NW 157 STREET MIAMI, FLORIDA 3314 Over the past ten years, the technology ised in anal tical chemistry has advanced to the point of detection in the part per billion range. Along with the capability to detect in this very low range, comes more stringent enforcement by regulatory agencies of operating permits concerning present and potential pollutants created by metal finishing and manufacturing processes. Sophisticated analytical instrumentation such as atomic absorption spectrophotometers, gas chromatographs, and auto-analyzers are now used in the environmental laboratory to test effluents and wastes for metals, volatile organics, cyanides, and phenols. These represent a small number of pollutants now regulated in discharges in the metal finishing industry. Officials of environmental regulatory agencies have stated that pollution control regulations for metal finishers as well as other industrial manufacturing processes that create waste streams, will continue to get even more stringent as technology improves to be able to detect pollutants at even lower levels. In order to insure that metal finishing industries meet all compliance standards for regulatory agency permits, it is to their advantage to use, or have, an on site certified laboratory that can accurately analyze incoming raw product quality, as well as process 1

2 effluent quality prior to routine sampling by regulatory agencies. The reliability of laboratory data is directly relational to the quality control data generated by the analysis of spiked duplicate samples as well as EPA QC check samples with each analytical run. The quality control program of a certified analytical laboratory employs several data validation techniques to insure correct results (Table 1). First, the instrument or method is calibrated with a reagent blank plus three to five working standards. After a standard curve has established the working range of the experiment, a series of quality control samples are run to ultimately validate the ten unknown samples that will follow. Assuming that the instrument/method is calibrated, a blank is run again to establish a zero baseline after running the standard material but prior to analysis of samples. Next, an EPA QC check sample or verification standard is run. This material is sent to laboratories by the EPA or other commercial manufacturers with the range of known results. QC check samples are usually at a concentration that is not a point on the standard curve, but between two points on the curve. This sample really provides a check on your standard preparation procedure and measures the dependability of your standard curve. QC check material must fall between 8% - 12% of the true value to continue. Duplicated matrix spikes are then analyzed to measure the accuracy and precision of the experiment. Matrix spikes are samples of the matrix in question (i.e. soils, waters, wastes, sludges) spiked with a known amount of the analyte in question. The measured result vs. the theoretical result expressed as a percent is % 2

3 Recovery (%R). This procedure is performed in duplicate in order to generate precision data, expressed as the difference between duplicates or % Relative Standard Deviation (%RSD). Percent Spike Recovery and Percent Relative standard Deviation are then calculated and compared to method control limits. Control limits are established by %R and %RSD values tracked on Shewhart quality control charts. Tables 2-5 show charts for accuracy and precision for the analysis of copper by flame atomic absorption and cyanide analysis by auto-analyzer. Upper and lower control limits as well as warning limits will show when an experiment is out of control or going out of control. Anything found to be outside of the control limits is subject to question and should be reanalyzed. Control limits are updated quarterly based on %R and %RSD values from previous quarters analysis. Good analytical data typically has between 8% and 11% spike recovery and between % and 1% relative standard deviation. After verification by each of the above criteria, the system may analyze ten (1) unknown samples along with any dilutions that may have to be run. After the last sample is run, the process starts over again by re-analyzing a blank. This may seem like to much to go through just to analyze one sample for one analyte, but for a regulated manufacturing process this could be the difference between getting a "Notice of Violationtt with involving a fine, or being below any regulated limits. For precious metal recovery operations, it could mean the loss of profit that you thought would be there, but after processing based - on Ilinvalid" analytical data, the final product is somewhat less than expected. - 3

4 Quality Control techniques as described in this paper should be incorporated into each and every analysis performed by a certified laboratory. It is not unreasonable for users to request a copy of the laboratory quality control plan, as well as quality control data for any analysis performed. If you are going to be using a laboratory on a regular basis it would also not be unreasonable to ask for a tour of the facility to make sure that lab is following all procedures spelled out in its Quality Control Plan. 4

5 LABORATORY QA / QC PROGRAM INSTRUMENT / METHOD CALIBRATION DAILY BLANK V E R I F I CAT IO N STA N D AR EPA QC CHECK SAMPLE SPIKE #I SPIKE #2 CALCULATE PRECISION (% RSD) CALCULATE ACCURACY (% R) IF % RSD AND % R FALL WITHIN CONTROL LIMITS... WE WILL ANALYZE 1 SAMPLES. TABLE 1

6 I I I COPPER (FLAME) EPA METHOD 22.1 d A X Y >. U a 3 U U a o I LAST 1 DATA POINTS TABLE 2

7 , COPPER (FLAME).5 EPA METHOD x' Y z I 1 I I I I I LAST 1 DATA POINTS TABLE 3

8 CYANIDE.5 EPA METHOD I 1 1 I 1 I I I I LAST 1 DATA POINTS TABLE 4

9 I Q -2 4 I I I I I I?':CSL?t'?Y -

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