## 1 Introduction  
Beer is the most popular alcoholic beverage in America [1]. Interest in craft beers in the United States has led to the substantial increase in small scale breweries that typically cannot afford sophisticated analytical techniques. A market potentially exists, therefore, for independent entities which have access to laboratories and expensive instrumentation to provide analytical services to breweries. The analysis of organic chemicals in beer samples has quality control and authenticity applications, and can also provide information to the brewer to improve the efficiency of the process, quality of product and discover the source of problems in the system. Beer is a complex mixture of over 800 organic molecules ranging from the ng/L to percent concentrations [2]. The major aroma and taste influencing compounds are considered to be the esters and alcohols formed during the fermentation process. Esters contribute to a beer's bouquet, but can result in off-flavors when present at higher concentrations. Higher alcohols are formed in the Ehrlich pathway, which proceeds when amino acids in the word are taken up by yeast. Information about the amino acids in beer, therefore, may be used as indicators for the fermentation performance. Esters are produced as a result of yeast metabolism. Resulting ester and alcohol concentrations can provide information about word composition, fermentation parameters, and yeast strains. Nuclear Magnetic Resonance (NMR) is a common chemical characterization technique. The instrument is typically used to provide structural information about organic compounds. It also has the capability to generate quantitative information for components in complex mixtures. The instrument utilizes a strong magnetic field to cause the alignment of a fraction of the nuclear spins in a sample, which are then capable of absorbing radio frequency radiation. The frequency absorbed depends on the chemical environment of the absorbing nucleus. The strength of absorption at a given frequency depends on the concentration of the chemical and number of nuclei in an identical chemical environment. Therefore, if the number of identical nuclei are known for a given molecule, the concentration can be determined by comparison to an internal standard of known concentrations. [PERSON] et al. [3] used proton NMR to quantify organic and amino acids in beer samples, and compared their results to those obtained by High Performance Liquid Chromatography (HPLC) and capillary electrophoresis. The methods were found to be in good agreement. [PERSON] et al. [4] investigated multivariate analysis of NMR and Fourier Transform Infrared Spectrometry (FTIR) data as a potential tool for the quality control of beer. They applied Principal Component Analysis (PCA) to data obtained from 50 beer samples to be able to group beers with common characteristics. The same group used PCA of proton NMR data in order to be able to investigate effects of brewing site and date of production [5]. A similar approach has been reported by [PERSON] et al. [6], for potential application to quality control of beer. A limitation of NMR is the relatively poor detection limits. Typically, sample concentrations below approximately 10 mg/L are not observable. For volatile substances at lower concentrations (such as alcohols, esters, aldehydes, ketones, and sulfur compounds), headspace capillary Gas Chromatography (GC) is commonly used. Headspace Solid-Phase Microextraction (SPME) is a simpler and less expensive alternative to static headspace. The method involves exposing a fiber to the headspace in order to concentrate the volatile analyte on the fiber surface. The analyses are subsequently thermally desorbed from the fiber in the GC inlet. SPME has been applied to a wide variety of sample types including beer. [PERSON] et al. [7] compared static headspace and SPME for the analysis of alcohols and esters in beers. They found the two methods to be highly correlated and suggested SPME as an inexpensive alternative to automated static headspace.