单四级杆GC-MS分析环境样品中VOC的优势体现

　　Introduction

　　A method was developed for the ana1ysis of volatile organic compounds ( VOCs ) with the Thermo Scientific ISQ single quadrupole GC-MS using quallty control requirements based on United States Environmental Protection Agency ( EPA ) methodologies . This requlres Integratlon of a range of instrumentation , from the sample Introduction system to the gas chromatograph and mass spectrometer, to the software for data interpretation , analysis and reporting.1 While the overall process of analyzing VOC is a mature technique , there are continuous innovations that allow laboratories to meet lower detection limits and analyze new compounds to comply with changing regulations , with higher throughput and improved quality.

　　Instruments

　　TheISQTM GC-MS was evaluated at a scanning speed of 2,650 u/sec, which represents 10 full scan mass spectra taken per second ( scanning m/z 35 to 30O in 0.1 sec). An OI EclipseTM 4660 Purge-and-Trap Sample Concentrator equipped with a sample heater and 4551A autosampler were used to deliver 5 mL of sample for analysis. The internal standard and surrogates were added by the Standard Addition Module ( SAM ) unit. The calibration curve range was 0.4 µg/L to 40 µg/L in the sample. The on column amount for each compound was 0.5ng to 5ng due to the 40 mL/min split flow during the injection.

　　Conclusions

　　Improvements to the method were tested by combining changes to the chromatography, employing the capabilities of the hardware , and applying a software package developed around routine GC/MS workflows . By combining these techniques , laboratories can achieve an average decrease of 50 % of the analyst review time combined with an increased number of samples that can be analyzed during a 12-hour time period while also attaining lower MDLs . All of these improvements resulted In doubling the throughput of samples analyzed in a 12-hour time period -from 24 to 48 samplcs . The ISQ single quadrupole GC-MS was evaluated and found to provide good sensitivity, spectral purity and linear dynamic range for the method.