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"A Dynamic Site Investigation Adaptive Sampling and Analysis Program for Operable Unit 1 at Hanscom Air Force Base"

Page 59
"To test the data generation software, comparisons were made between the EnviroQuant and Ion Signature quantitative deconvolution software systems. Also shown in Tables 8-11 are the initial and continuing calibration line parameters and %RSD RFcal and the percent difference as determined by the EnviroQuant software. Note that all GC/MS total ion current chromatograms were acquired by HP’s data acquisition system. Both Ion Signature and EnviroQuant, therefore, analyzed the same data files. The tables reveal no statistical differences in the information obtained. Moreover, the %RSD’s for the eighteen VOC RFcal’s were well within the field criterion of 30% for two-thirds of the target compounds and 40% for the remaining one-third of the organics established for this field study. Good agreement was also found for PCBs and PAH except for naphthalene. EnviroQuant produced a 65% RSD RFcal in comparison to the 37% RSD calculated by Ion Signature. Excellent agreement was also obtained between the two data analysis systems for the continuing calibration data. The VOC and semivolatile data were typically within the 30% required of fixed-based laboratory data."

"To determine instrument and method stability in the field, each sample’s internal standard signal was compared against the corresponding average internal standard signal calculated over the first two calibration curves. The internal standard signal was inside the -50 to 150 percent difference HAFB DQO for 134 of 157 samples (85% success rate) analyzed by Ion Signature. EnviroQuant fell outside of the DQO for 32 of the same samples, while missing the internal standard identity in two samples completely for a 78% success rate. Both data analysis systems fell out of QC because of coeluting matrix constituent(s) that affected the internal standard integration."

Page 60
"Table 27 shows Ion Signature and EnviroQuant site sample data comparisons for the same calibration files where at least one of the data analysis systems identified a target compound above the reporting limit. Differences between the two calculated concentrations were due to each data system’s peak identification and integration routines. For example, Ion Signature provided better integration where matrix constituents coeluted with either target compounds or internal standards. EnviroQuant cut peaks in half depending upon where peak separation was determined by the software. Target compound concentrations in file #’s 100.D, 178.D, 179.D, and 194.D were reported by Ion Signature whereas, EnviroQuant estimated their concentration below the reporting limit. In addition, EnviroQuant missed compounds in file #'s 102.D, 143.D, and 178.D that were well above the reporting limit, with Ion Signature missing one compound in file # 031.D. Of the 205 reported compounds by both software systems, 85% had RPD’s 50% and 65% had RPD’s 20%. This is remarkable given that both data systems identified peaks and integrated signals very differently."

"Innovations in Site Characterization"

Page xviii

"Cost Per Sample:

Use of the Ion Signature Software reduced GC/MS run times by a factor of 2-4, which increased sample throughput, and thus decreased both direct costs (e.g., labor) and indirect costs (by decreasing turn-around time of results within the context of a dynamic workplan."

"Site-Specific Accuracy/Precision Achieved:

The performance of the Ion Signature software was compared with the data processing software typically supplied with an HP GC/MS system. Of the 158 VOC samples analyzed, 4 samples required re-analysis by Ion Signature to resolve interference or linearity issues, compared to 25 re-analyses required using the traditional software package."

"The internal standard signal was within the ± 50% difference acceptance range 85% of the time for the Ion Signature software, compared to 78% for the other software."

"Software Performance Information:

The Ion Signature software is capable of identifying low concentrations of target analytes in the presence of high levels of matrix interferences. By "seeing through" the matrix interferences, the software reduces the need for sample re-analyses and dilution, and increases confidence in surrogate, internal standard, and target compound identification and quantification."

Page 12
"Most MS data analysis software packages can extract individual ion fragments, however the underlying mathematical algorithms unique to the Ion Signature software facilitate compound identification for these samples regardless of matrix interferences. Ion Signature quantitative deconvolution software provides the technology necessary to reduce long chromatographic run times from 30-40 minutes to 10 minutes."

Page 24
"Observations and lessons learned:

The Ion Signature quantitative deconvolution software can be used to obtain compound selectivity rather than adjusting the gas chromatography operating conditions. This decreases the per sample analysis time and increases the number of samples that can be analyzed per day per instrument over standard GC/MS instruments. The Software algorithms which "look through" non-target MS ion signals can unambiguously determine compound identity, minimizing masking of low-concentration target compounds by high-concentration matrix interferents. In this context, low-level target compounds are not lost because of the need to dilute the sample. Use of the Software algorithms makes sample dilution less necessary, keeping detection limits low and saving time and money."