Analysis of Geosmin and 2-Methylisoborneol (MIB) by Solid Phase Micro Extraction (SPME) and CI-MS-MS using the Varian 240 MS - - Chromatography Online
Analysis of Geosmin and 2-Methylisoborneol (MIB) by Solid Phase Micro Extraction (SPME) and CI-MS-MS using the Varian 240 MS


The Application Notebook



Figure 1
Two of the most commonly occurring unpleasant odor-causing compounds in drinking water are geosmin and 2-methylisoborneol (MIB) (Figure 1). Geosmin is produced primarily by blue-green algae (cyanobacteria) and actinomycete bacteria, and MIB is produced by certain species of cyanobacteria, primarily Oscillatoria. Many environmental laboratories are required to detect these compounds as low as 1–3 ppt concentration and measure quantitatively at 5 ppt.


MS-MS parameters
Analytical methods utilizing SPME and GC–MS for the detection of geosmin and MIB have become standard procedure. Most reported methods can determine these two components quantitatively at 5 ng/L using EI-MS in SIM mode. Significant background interference limited the method to quantify at lower levels for these two components. In this note, a CI-MS-MS method was developed using a 2 cm 50/30 mm DVB/ Carboxen/PDMS SPME fiber and the Varian 240-MS ion trap mass spectrometer to measure geosmin and 2-methylisoborneol (MIB) quantitatively in water at concentrations near 1 ppt with good confidence.

Materials and Methods


Figure 2
A 100-μg/mL stock solution of geosmin and MIB in methanol, IBMP and IPMP in methanol were purchased from Supelco (Bellefonte, Pennsylvania). A series of calibration standard were prepared in reagent water at concentrations ranging from 1 to 50 ppt (1, 2, 5, 10, 20, and 50 ppt) with 50 ppt of IBMP as internal standard and 50 ppt of IPMP as surrogate standard.

GC and SPME conditions:
Column: VF-5ms, 30 m 0.25 mm, 0.25 mm film
SPME fiber: 2cm StableFlex coated with 50/30mm DVB/Carboxen/PDMS
Oven: 35C for 2 min, to 125C hold for 1 min, 10C, to 300C hold for 3 min, 25C /min to 320, hold 2 min.
Flow rate: 1 mL/min
Injector: 1177
Sample: 12.5 mL water

MS Conditions:
Trap: 180C
Manifold: 50C
Transfer Line: 250C
Target TIC: 5000
Max ion time: 2500 ms
Prescan Ion Time: 250 ms
CI reagent: methanol

Results and Discussion


Figure 3
Geosmin and 2-methylisoborneol were determined quantitatively using the product ions described in the method by CI-MS-MS with methanol as liquid reagent. The matrix effects were eliminated using the MS-MS mode. This greatly improved the sensitivity of the method. Under current conditions, both geosmin and MIB can be determined quantitatively as low as one ppt. (Figure 3).


ADVERTISEMENT

blog comments powered by Disqus
LCGC E-mail Newsletters
Global E-newsletters subscribe here:




 

LCGC COLUMNISTS 2014

Column Watch: Ron Majors, established authority on new column technologies, keeps readers up-to-date with new sample preparation trends in all branches of chromatography and reviews developments. LATEST: When Bad Things Happen to Good Food: Applications of HPLC to Detect Food Adulteration


Perspectives in Modern HPLC: Michael W. Dong is a senior scientist in Small Molecule Drug Discovery at Genentech in South San Francisco, California. He is responsible for new technologies, automation, and supporting late-stage research projects in small molecule analytical chemistry and QC of small molecule pharmaceutical sciences. LATEST: HPLC for Characterization and Quality Control of Therapeutic Monoclonal Antibodies


MS — The Practical Art: Kate Yu brings her expertise in the field of mass spectrometry and hyphenated techniques to the pages of LCGC. In this column she examines the mass spectrometric side of coupled liquid and gas-phase systems. Troubleshooting-style articles provide readers with invaluable advice for getting the most from their mass spectrometers. LATEST: Radical Mass Spectrometry as a New Frontier for Bioanalysis


LC Troubleshooting: LC Troubleshooting sets about making HPLC methods easier to master. By covering the basics of liquid chromatography separations and instrumentation, John Dolan is able to highlight common problems and provide remedies for them. LATEST: How Much Can I Inject? Part I: Injecting in Mobile Phase


More LCGC Columnists>>

LCGC North America Editorial Advisory Board>>

LCGC Europe Editorial Advisory Board>>

LCGC Editorial Team Contacts>>


Source: The Application Notebook,
Click here