Standard Reference Material 2881 - National Institute of Standards ...

educes the data set to groups of three strategic points where each group defines thebeginning, center, and ending of each peak located. The peak areas are found from thestrategic points using a commonplace polygonal area calculation routine. Peaks withstatistically insignificant height or area are then discarded. Unbiased peak integration isa cornerstone of SRM 2881.The output files containing peak mass and peak area created by MassSpectatorwere transferred to Microsoft (Redwood, WA) Excel (2003 version). A spreadsheet wasused since the amount of data from many integrated data sets easily fit onto a singleworksheet. Excel has the advantage that macro scripts can be written in Visual Basic(VBA). This means that once the spreadsheet layout and input/output structure aredetermined all statistical software can be written in VBA. Thus, a simple VBA programwas written which transfers the data and its relevant information into the spreadsheetfrom the output of MassSpectator. A second, more complex VBA program was written torecalibrate as required the mass axis of the data using the expected largest five to tenpeaks from the polymer of the mix. The data were then separated into series by thepolymer end group and the appropriate numbers such as total mass, total area, M n , M w ,and M z of each series were computed. It should be noted that even the detailedinstructions for the experiment were developed and contained in the Excel spreadsheet.This was done so that both the experimental protocols with any modification made by theinstrument operator and the data analysis of that experiment are contained together in thesame file for convenience and for data record keeping. While the overall time to collect35 spectra was 1.5 d to 2.5 d, the MassSpectator and Excel VBA software suite allowedus to analyze 35 or so spectra in (2 to 3) h.26