ES&T EDITORIAL
Guidelines for GC/MS identification The advent of GC/MS technology and the avail ability of commercial instruments at reasonable costs have produced an avalanche of data on the occurrence and distribution of trace organic contaminants in the environment. From the point of view of industrialists, utility managers, and federal agency personnel, this trend has the potential for increasing regulatory pressures. From the point of view of editors, the ex plosion of research interest in this subject and the re sulting proliferation of manuscripts that claim iden tification of organic chemical structures is producing certain quality control problems. The editorial problem is related to the fact that GC/MS instruments are sensitive and sophisticated and inevitably produce large quantities of data that may or may not have meaning. The responsibility for arranging and interpreting data in scientifically ac ceptable form is under the control of the instrument operator and the manuscript author. The responsi bility of scientific journals is to urge adoption of rea sonable guidelines and policies guaranteeing that minimum quality standards are followed with regard to data presentation and interpretation. To begin this process in ES& T, I suggest the following guidelines for the presentation and interpretation of GC/MS data. We will follow these guidelines with all research manuscripts on an interim basis from the present time through December 1982. During this time, I welcome any comments you may have with regard to these guidelines. Based upon our experience in the next few months and communications from you, an iterated form of these guidelines will appear in the January 1983 Editorial Policy Statement. Our most general guideline is for the presentation of sufficient analytical detail in the experimental section to enable another researcher to duplicate the work. In terms of hardware and operating conditions, this minimally includes specification of type and source of columns, carrier gas and flow rate, operating temperature range, mode of ionization, scan cycle time, ion source temperature, and model of mass spectrometer used. 0013-936X/82/0916-143A$01.25 © 1982 American Chemical Society
If the purpose of the work is to identify structures of organic components in mixtures, then the provision of good quality electron ionization (EI) spectra are minimally required to employ the description of "tentative structural assignment" to a component, if these data match library spectral data or literature sources. Currently employed matching procedures (computer or manual) are somewhat subjective; therefore, authors should present evidence of their matching criteria. If these "tentative structural as signments" are supported by additional data such as chemical ionization (CI), accurate mass (±0.005 amu), or retention data, then the description "confi dent structural assignment" may be used. Only when an authentic specimen of the proposed structure is obtained and its EI, CI, and retention data are shown to match those of the component within experimental error can the description "confirmed structural as signment" be employed. It is desirable that authors strive to report only confirmed structural assignments. If authentic com pounds are not available to researchers, it may be necessary to synthesize them. For the time being, ES& Τ will accept structural assignments at each of these three levels of confidence. Even for components for which no computer or manual matching exists, it is desirable to provide as minimal data EI, CI, and retention data (e.g., Kovats index), which is readily obtainable by almost all GC/MS users. In this case, the component would be described as "unidentified" but the data would be available in the literature for the use of others. The most important need at present is to be able to dis tinguish easily the level of confidence in presented literature data.
Environ. Sci. Technol., Vol. 16, No. 3, 1982
143A
