Gas chromatography (GC) is a technique that includes all chromatographic processes in which a substance to be analyzed is in the gaseous state or is converted into such a state. Miniaturized GCs are in high demand due to their portability, ability to operate in the field, low power requirements and low material cost. The focus of this thesis is on the development, testing and applications of portable analytical instruments, specifically miniature gas chromatographs. In the first chapter, two portable gas chromatograph prototypes are described; including a miniature GC and an auto sampling GC. The second chapter describes student experiment development that incorporates mini GCs into the academic chemistry curriculum and focuses on teaching principles of chromatography or use a gas chromatograph as a tool. The third chapter focuses on development, testing and application of a portable auto sampling prototype GC to aid in the production of biofuels.

Note:

Dietary cyclopropenoid fatty acids (CPFA) have long been known to cause pronounced physiological disorders in both farm and laboratory animals. Past work has shown CPFA to be a powerful promoter of carcinogenesis in trout, rats and mice. Sterculic and malvalic acids (CPFA's) are found in seed lipids of plants from the order Malvales. Two members of this order are cotton and kapok, both of which are used extensively as cooking oils for human consumption. Present chemical and instrumental methods of analysis for CPFA are effective only at CPFA levels above 0.1%, and accurate only at levels above 1%. A more sensitive method of analysis was developed exploiting recent technological advances in glass capillary gas chromatography (GCGC). By the use of cold on-column injection, and positioning of the column at the base of the detector flame, this method eliminates two problem areas found in other GC methods. The other common component involved in CPFA decomposition, during GC analysis, is the column. Vitrious silica columns with an inert stationary phase, SE-30, were shown to separate the highly reactive CPFA without decomposition. Proof of stability during analysis was obtained by changing the variables of relative time on column and column temperature. This method not only allows individual determination of sterculic and malvalic acid concentrations, it is rapid, accurate (to the 70 parts per million range), and is superior to other instrumental and chemical methods. The CPFA concentration for okra, hollyhock, cheese weed, seashore mallow, kapok, and white cap cottonseed oil are as follows: 0.3% to 0.92%, 0.33%, 2.6%, 2.6%, 12.8%, and 75ppm, respectively. The two different values for okra were found because seeds from two different growing seasons were analyzed. No CPFA could be detected in Diet Imperial Margarine, raw cocoa beans, cocoa butter or Lucca's winterized cottonseed oil. / Graduation date: 1987

The use of gas chromatography for the separation, comparison, and subsequent identification of flavor volatiles from food products has proven highly successful in recent years. The development of various techniques for the concentration of the volatiles before gas chromatographic analysis has greatly extended the use of this important analytical tool. The injection of vapors directly into the chromatograph without prior concentration is the simplest method and has been used successfully on many food products. However, the use of this technique on the volatiles of fishery products has met with limited success. The complexity and nature of the flavor compounds found in fishery products have required the use of highly sensitive instruments and columns with very efficient separation power. The purpose of this investigation was to develop a method for the separation and comparison of volatiles from fishery products by this direct vapor injection technique. Preliminary investigations showed that a nine foot column of diisodecyl phthalate on 80/100 mesh, methanoic KOH treated, celite 545, operated isothermally at 35°C, would give satisfactory separation of one to three ml samples of volatiles from heated fishery products. The technique was not, however, sensitive enough to allow direct sampling of cold products unless they were highly spoiled or autoxidized. This investigation showed that direct vapor injection, using the column and conditions described, will show differences between size and number of peaks in heated fresh, oxidized, and spoiled fishery products. Several peaks in autoxidizing menhaden oil were shown to increase with hours of oxidation and a peak with the same retention time as trimethylamine was observed in the chromatograms of spoiled fish. The direct injection technique did not show large differences between fresh dover sole, rockfish, oysters, or beef. Tentative identification of various peaks from the chromatograms of oxidized salmon oil was attempted by comparison of retention data to known compounds and by functional group analysis by the method of Hoff and Feit (34). In this manner the possible existance of C₁ to C₇ alkanals, 2-hexen-1-al, methane, heptane, ethanol, butanol, and acetone was shown. The methods of tentative identification used were preliminary in nature and confirming tests would be necessary before positive identifications could be made. A comparison of chromatograms from fish, oysters, beef, and fish oils showed that several similar peaks appear in every case. These peaks were found at retention times of 0.71, 0.87, 1.42, 2.21, 2.83, 3.62, 5.20, and 5.51 minutes. / Graduation date: 1964

No description available.

Thesis (Ph.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / The recent discovery of a number of metabolites of estrogens has necessitated the development of new methods for their analysis. The available methods of proven merit fall short of determining these newer fractions. Moreover, these methods are too time consuming to determine the daily excretion of estrogenic steroids. The development of a relatively rapid and highly sensitive methodfor the estimation of several estrogens was, therefore, undertaken. The procedure involves hydrolysis, extraction, preliminary purification and separation, acetylation and gas chromatography of the steroids. Simultaneous separation and quantification by gas-liquid chromatography (GLC) not only allows a more rapid analysis but sensitivity is also increased by the use of ionization detectors. Determination of the optimal flow rate of hydrogen, air and carrier gas was found necessary for obtaining maximum detection response. Detector linearity for seven estrogens over an adequate range was established. Since free estrogens suffer severe adsorption on the gas chromatographic column and generally do not separate well, the steroids were analyzed as suitable derivatives. After examining several such derivatives (acetates, formate, trifluoroacetate, trimethylsilyl ethers) the acetates were found to be most suitable for the specific purpose. Optimal conditions for the acetylation of steroids in submicrogram quantities were established. The effect of the solid support, stationary phase, priming of the column with estrogens and solvent impurity in quantitative analysis by gas chromatography was also investigated. Preliminary separation of estrogens into separate groups was necessary because of poor resolution and long retention times resulting in poor detector response. Moreover, in a crude urine extract, the large number of contaminants obscuring the peaks of the lesser estrogen components, mandated preliminary purification. Thin-layer chromatography crtc) was found to be a versatile tool for this purpose. Among several solvent systems developed, three were found to be eminently suitable. TLC in System I (benzene:ethyl acetate 1:1) separates the estrogens into four fractions: (a) estrone and 2-methoxyestrone, (b) ring-D-alpha-ketols and estradiol, (c) 16-epiestriol, and (d) estriol. Further TLC of fraction (b) in System II (pet. ether:dichloromethane:ethanol 10:9:1) was found necessary to separate these estrogens from the neutral 17-ketosteroid. An alternate method of preliminary purification and separation for the measurement of the three classical estrogens in low titer urine, involving alumina chromatography, has been developed. Following these preliminary procedures GLC permitted rapid separation and highly sensitive quantification of the individual fractions [TRUNCATED] / 2031-01-01

by Cheung Yiu-ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1990. / Includes bibliographies. / ACKNOWLEDGMENT / ABSTRACT / Chapter CHAPTER 1 --- GENERAL INTRODUCTION --- p.1 / Chapter 1.1 --- REVIEW OF GAS-LIQUID CHROMATOGRAPHY --- p.1 / Chapter 1.2 --- APPLICATION OF GAS-LIQUID CHROMATOGRAPHY IN DRUG ANALYSIS --- p.8 / Chapter 1.3 --- AIMS OF THE PRESENT WORK --- p.9 / REFERENCES --- p.11 / Chapter CHAPTER 2 --- GAS-LIQUID CHROMATOGRAPHIC DETERMINATION OF ACTIVE INGREDIENTS IN COUGH-COLD SYRUP FORMULATIONS --- p.12 / Chapter 2.1 --- INTRODUCTION --- p.12 / Chapter 2.2 --- EXPERIMENTAL --- p.16 / Chapter 2.3 --- RESULTS AND DISCUSSION --- p.22 / Chapter 2.4 --- CONCLUSION --- p.73 / REFERENCES --- p.74 / Chapter CHAPTER 3 --- "GAS-LIQUID CHROMATOGRAPHIC DETERMINATION OF ATROPINE SULFATE/HYOSCYAMINE SULFATE, HOMATROPINE HYDROBROMIDE AND HYOSCINE HYDROBROMIDE IN PHARMACEUTICAL PREPARATIONS" --- p.75 / Chapter 3.1 --- INTRODUCTION --- p.75 / Chapter 3.2 --- EXPERIMENTAL --- p.79 / Chapter 3.3 --- RESULTS AND DISCUSSION --- p.85 / Chapter 3.4 --- CONCLUSION --- p.126 / REFERENCES --- p.127 / APPENDIX --- p.128 / Chapter A.1 --- INTRODUCTION --- p.128 / Chapter A.2 --- EXPERIMENTAL --- p.129 / Chapter A.3 --- RESULTS AND DISCUSSION --- p.132 / Chapter A.4 --- CONCLUSION --- p.147 / REFERENCE --- p.147 / LEGENDS FOR FIGURES / LEGENDS FOR TABLES

No description available.

While research into improving data quality from analytical instrumentation has gone on for decades, only recently has research been done to improve information extraction methods. One of these methods, correlation analysis, is based upon the shifting of one function relative to another and determining a correlation value for each displacement. The cross correlation algorithm allows one to compare two files and find the similarities that exist, the convolution operation combines two functions two dimensionally (e.g. any input into an analytical instrument convolves with that instrument response to give the output) and deconvolution separates functions that have convolved together. In correlation chromatography, multiple injections are made into a chromatograph at a rate which overlaps the instrument response to each injection. Injection intervals must be set to be as random as possible within limits set by peak widths and number. When the input pattern representation is deconvolved from the resulting output, the effect of that input is removed to give the instrument response to one injection. Since the operation averages all the information in the output, random noise is diminished and signal-to-noise ratios are enhanced. The most obvious application of correlation chromatography is in trace analysis. Signal-to-noise enhancements may be maximized by treating the output data (for example, with a baseline subtraction) before the deconvolution operation. System nonstationarities such as injector nonreproducibility and detector drift cause baseline or "correlation" noise, which limit attainable signal-to-noise enhancements to about half of what is theoretically possible. Correlation noise has been used to provide information about changes in system conditions. For example, a given concentration change that occurs over the course of a multiple injection sequence causes a reproducible correlation noise pattern; doubling the concentration change will double the amplitude of each point in the noise pattern. This correlation noise is much more amenable to computer analysis and, since it is still the result of signal averaging, the effect of random fluctuations and noise is reduced. A method for simulating conventional coupled column separations by means of time domain convolution of chromatograms from single column separations is presented.

No description available.