• Elliptical orbital studies of H21 and H2 molecules /|nS. K. Gupta. -- 260 St. Catharines, Ont. : [s. n.],

      Gupta, S. K.; Department of Chemistry (Brock University, 1971-07-09)
      Calculations are performed on the \S <:Jd ground states of d ' + the H and HC) molecules using a basis set of non-integral ~ ~ I elliptical orbitals. Different variational wavefunctions constructed i- for H~ involved one parameter to three par~~eter variation. In order to l"'educe the ntunber of parameters in most commonly 0- used basis orbitals set, the importance of the term (,+~) Y\ over the term ;u 'Where n is a variational pararneter and the value of cr may be given by boundary condition or cusp condition is outlined in Chapters II and III. It is found that the two parameter -+ <J""' wavefunction for H~ including the ternl (~+~) , a- given by the bound~ condition, gives lower variational energies than any wavefunction published to date for small and moderate internuclear separations. c;. In order to find out the importance of the term (I +~ ) Y\ over ;U for the two electron problem, the variational energy is computed for the H~ molecule from unrestricted two parameter closed shell wavefunctions including the term U+ft)<J w11ere the value of rr is obtained from the boundary condition in one case and from the cusp condition in the second case. In order to take into account in-out correlation partially, open shell calculation for the ground state of the hydrogen molecule for R =1.4 (equilibrium internuclear separation) is perfonaed. The results are excellent.
    • Enantiodivergent chemoenzymatic synthesis of Balanol and approaches to the synthesis of (+)-Codine

      Gilmet, Jacqueline; Department of Chemistry (Brock University, 2010-10-25)
      The present thesis reviews the development of a formal enantiodivergent synthesis of the (+)- and (-)-isomers of balanol. This approach commences from a cis-dihydrodiol derived from the enzymatic dihydroxylation of bromobenzene. The stereochemistry of the diol is used to direct the synthesis of two different aziridines, each used in the formal synthesis of one enantiomer of balanol. Also described are several enantioselective approaches to (+ )-codeine. Each strategy begins with the enzymatic dihydroxylation of p-bromoethylbenzene and involves a Mitsunobu inversion and intramolecular Heck reaction as key steps.
    • Epimeric L-Proline Derived Imidazolone Chiral Auxiliaries for the Stereoselective Alkylative Birch Reduction of Aromatic Esters and Benzonitriles

      Cadwallader, Dusty; Department of Chemistry
      Described in this thesis are several advancements of imidazolidinone chiral auxiliaries. Initially, attempts were made to develop a N-heterocyclic carbene ligand derived from the N-benzyl analog of the auxiliary. Attempts to design a monodentate ligand as well as a bidentate ligand bearing an alcohol side chain were both shown to be unsuccessful. Work on the N-phenyl variant of the auxiliary included expanding upon our recently discovered methodology; a Birch reduction alkylation sequence of an aromatic ester yielding chiral quaternary carbon centres in a stereoselective matter. In substrates that demonstrate poor stereoselectivity, modification of the auxiliary to include a larger neopentoxy directing group gives way to increased selectivity. This work also includes the same Birch reduction alkylation sequence on a series of benzonitrile substrates with up to 64:36 diastereomeric ratio from either epimer of the auxiliary. The low selectivity of the benzonitrile substrates is offset by the resulting diastereomers of the dihydrobenzonitrile products being chromatographically separable. This results in the first preparation of optically pure quaternary carbons alpha to nitrile by Birch-type reductive alkylation. Progress was also made in the manipulation of chiral auxiliaries bearing the chiral alkoxy moiety. These functional groups were transformed into hemiaminals by citric acid hydrolysis in a 3:2 ratio with imidazolone by-products formed by acid mediated elimination of alcohol.
    • Epimeric Pyrroloimidazolone Auxiliaries in the Diastereoselective Synthesis of Chiral N-Ferrocenyl/N-Phenyl Ligands and Arene-Chromium Tricarbonyl Complexes

      Wilson-Konderka; Department of Chemistry
      This thesis describes the synthesis and use of an N-based L-proline derived chiral auxiliary/directing group for selective synthesis of planar chiral and central chiral products. A series of planar chiral ferrocenes were prepared, and converted to chloroimidazoliums and complexed to palladium via oxidative addition. In addition to this, a centrally chiral Ir(I) catalyst was prepared for the purpose of evaluating the importance of planar chirality for the induction of enantioselectivity in the Ir(I) catalyzed hydrogenations of 2-substituted quinolines. A lower enantioselectivity was observed, allowing the conclusion that planar chirality does contribute to the enantioselectivity. The pyrroloimidazolone directing group used to induce high diastereoselectivity in ferrocene lithiations (>95:5 dr) has been applied (with minor modifications) towards the diastereoselective lithiation of η6-arene chromium tricarbonyl complexes. The anti-epimer of the pyrroloimidazolone auxiliary undergoes pro-R lithiation in >95:5 dr. The syn-epimer of this auxiliary undergoes pro-S lithiation in >95:5 dr. The origin of selectivity is believed to be caused by a conformational bias exerted by the O-group. The selectivity of lithiations, and stereochemistry of all the products has been confirmed by a combination of X-ray analysis, transmetalation and deuteration experiments and by the preparation and comparison of solely planar chiral enantiomers.
    • ESI-MS[n] of anticancer pt[iv] organoamido complexes and their interactions with DNA-model compounds /

      Gurgi, Mohamedkamal Ahmed.; Department of Chemistry (Brock University, 2001-07-14)
      The general solution behaviour and" the major fragmentation pathways of the anticanceractive PtIV coordination complexes, trans, trans, cis, cis-[PtCIOH{N(pFC6F4) CH2h(pY)2] (1), trans, cis, cis-[Pt(OH)2{N(p-FC6F4)CH2h(Py)2] (2), trans, cis, cis-[Pt(OH)2{N(p-HC6F4)CH2h(Py)2] (3), trans, trans, cis, cis-[PtCIOH{N(pHC6F4) CH2h(Py)2] (4), and trans, trans, cis, cis-[PtOH(OCH3){N(p-HC6F4)CH2h(PY)2] (5) (Py = pyridine) have been deduced by positive-ion tandem-in-time ESI-MS. Overall, the acquired full-scan, positive-ion ESI-MS spectra of 2, 3, and 5 were characterized by the presence of relatively low-intensity [M+Nar and [M+Kt mass spectral peaks, whereas those of 1 and 4 were dominated by extremely intense [M+Hr peaks. Complexes 2 and 3 were also noted to form [2M+Ht and [2M+Nat dilneric cations. The source of Na + and K+ ions is believed to be the sample, the solvent systems used or the transport line carrying the sample solutions into the ES ion source. Further, the fragmentation pathway of all complexes studied was found to be almost identical with concurrent loss of py and H20 molecules, loss of a {N(p-YC6F4)CH2} (Y = F, H) group and/or concomitant release of the latter group and a py ligand being the most conunon. The photochemical degradation behaviour of 1 and 2 was also investigated using either fluorescent or ultraviolet light and some products of that degradation were positively identified. Altogether, light irradiation of solutions of both complexes resulted in cation cationisation, reductive-elimination, ligand-release, ligand-exchange and ligand-addition reactions. Finally, positive- and negative-ion ESI-MSn spectra of 5' -GMP, guanosine, inosine and products of their reactions with 1, 2,3, and 4 were also recorded. On the whole, full-scan ESI-MS spectra of the pure nucleobases revealed the presence of cationic and anionic species that are highly reflective of both their solution ionic composition and their propensity t9 form polymeric clusters. Analyses of mass spectra acquired from their reaction solutions with the aforementioned platinum complexes indicated very slow kinetics. However, all complexes investigated formed, to various degrees, Pt-nucleobase adducts with guanosine and inosine, but not with 5'-GMP. The products included species having coordination numbers of III, IV, V, and VI, among which the first-time· observed, coordinatively saturated, jive-coordinate PtlI-nucleobase complexes were of most interest. The latter complexes are presumably stabilized by 7tback- donation involving the filled d orbitals of the PtII centre and the empty pz· orbital of MeCN. All products, whose peaks appeared inlull-scan ESI-MS spectra, are believed to represent solution species rather than artifacts of gas-phase processes. Finally, negativeion ESI-MSn spectra recorded in reaction solutions of 1 and 4 with guanosine and of the latter complex with inosine revealed the negative-ion-ESI-MS first-time observed, noncovalent, nucleoside-chloride adducts, with the source of chloride anion being complexes 1 and 4 theillselves. In contrast, no such adducts were observed to form with Na25'-GMP or its protonated fonn. Few suggestions are offered for the possible cause(s) behind the absence of such adduct ions.
    • Exchange energy calculation of He-He with supermolecular one-matrix

      Bölük, Ebise Mualla; Department of Chemistry (Brock University, 1982-07-09)
      Exch~nge energy of the He-He system is calculated using the one-density matrix which has been modified according to the supermolecular density formula quoted by Kolos. The exchange energy integrals are computed analytically and by the Monte Carlo method. The results obtained from both ways compared favourably,with the results obtained from the SCF program HONDO
    • Exchange reactions of organic halides and organo-silicon compounds with boron tribromide and boron triiodide

      Hanna, Zaher S.; Department of Chemistry (Brock University, 1977-07-09)
      Reactions of the boron halides with organic halides and organo-silicon compounds have been investigated. The results show exchange of halogens between the BX3 (X = Br# 1) and the organic halidef exchange of the halogen of the C-X bond being proved. The rates of halogen exchange vary. Reaction of the heavier halides with organo-silicon compounds indicated that the silicon-carbon bonds ruptured in the absence of electronegative atom attached to the silicon. The presence of an electronegative atom (halogen or oxygen) attached to the silicon causes the bond between the silicon and the electronegative atom to be preferentially broken. Products of exchange reactions of the boron halides and the organic halides or the organo-silicon compounds were studied by use of 1H NMR and GC/MS. From these results some possible mechanisms for the exchange reactions are postulated, but further work is indicated to prove the real courses of the reactions
    • Experimental and Computational Studies on Copper and Hydrobenzoin Derivatives in Catalytic Asymmetric Reactions

      Belding, Lee; Department of Chemistry (Brock University, 2013-05-07)
      The use of theory to understand and facilitate catalytic enantioselective organic transformations involving copper and hydrobenzoin derivatives is reported. Section A details the use of theory to predict, facilitate, and understand a copper promoted amino oxygenation reaction reported by Chemler et al. Using Density Functional Theory (DFT), employing the hybrid B3LYP functional and a LanL2DZ/6-31G(d) basis set, the mechanistic details were studied on a N-tosyl-o-allylaniline and a [alpha]-methyl-[gamma]-alkenyl sulfonamide substrate. The results suggest the N-C bond formation proceeds via a cisaminocupration, and not through a radical-type mechanism. Additionally, the origin of diastereoselection observed with [alpha]-methyl-[gamma]-alkenyl sulfonamide arises from avoidance of unfavourable steric interactions between the methyl substituent and the N -protecting group. Section B details the computationally guided, experimental investigation of two hydrobenzoin derivatives as ligands/ catalysts, as well as the attempted synthesis of a third hydrobenzoin derivative. The bis-boronic acid derived from hydrobenzoin was successful as a Lewis acid catalyst in the Bignielli reaction and the Conia ene reaction, but provided only racemic products. The chiral diol derived from hydrobenzoin successfully increased the rate of the addition of diethyl zinc to benzaldehyde in the presence of titanium tetraisopropoxide, however poor enantioinduction was obseverved. Notably, the observed reactivity was successfully predicted by theoretical calculations.
    • Explorations of Intramolecular [5+2] Cycloadditions of Ring-Constrained Vinylcyclopropanes

      Bissett, Tyler; Department of Chemistry (Brock University, 2014-09-19)
      The first example of a [5+2] cycloaddition reaction wherein the olefin of the vinylcyclopropyl moiety is constrained in a carbocycle was explored, and possible reasons on the lack of reactivity of the substrate were studied. A simple model substrate was synthesized and subjected to cycloaddition conditions to determine if the reason for the lack of reactivity was related to the complexity of the substrate, or if the lack of “conjugative character” of the cyclopropyl ring with respect to the olefin is responsible. A more complex bicyclic substrate possessing an angular methyl group at the ring junction was also synthesized and explored, with evidence supporting the current theory of deconjugation of the cyclopropyl moiety.
    • Fast atom bombardment and electron impact mass spectrometry studies of some aryltin compounds and ferrocenes

      Luo, Yongchong.; Department of Chemistry (Brock University, 1993-07-09)
      Both El MS and FAB MS behavior of two groups of compounds, aryltin and ferrocene compounds, have been studied. For the aryltin compounds, the effect of substituent group position, substituent group type and ligand type on the El spectra have been explored in the El MS studies. The fragmentation mechanism has been investigated under El with linked scans, such as fragment ion scans(BJE), parent ion scans(B2JE) and constant neutral radical loss scans(B2(1-E)JE2). In the FAB MS studies, matrix optimization experiments have been carried out. The positive ion FAB MS studies focused on the effect of substituent group position, substituent group type and ligand type on the spectra. The fragmentation mechanisms of all the samples under positive ion FAB have been studied by means of the linked scans. The CA positive ion FAB fragmentation studies were also carried out for a typical sample. Negative ion FAB experiments of all the compounds have been done. And finally, the comparison of the El MS and FAB MS has been made. For ferrocenes, the studies concentrated on the fragmentation mechanism of each compound under El with linked scan techniques in the first field-free region and the applicability of positive/negative ion FAB MS to this group of compounds. The fragmentation mechanisms under positive ion FAB of those ferrocenes which can give positive ion FAB MS spectra were studied with the linked scan techniques. The CA +ve F AB fragmentation studies were carried out for a typical sample. Comparison of the E1 MS and FAB MS has been made.
    • The fast atom bombardment mass spectrometric analysis of the carbamate pesticide carbaryl

      Waters, Gregory J.; Department of Chemistry (Brock University, 1987-07-09)
      The carbamate pesticide, carbaryl, was quantitatively studied using fast atom bombardment mass spectrometry (FAB-MS). Mass spectra were obtained in the positive ion-mode using both 2-nitrophenyloctyl ether (NPOE) and 3-nitrobenzyl alcohol (NBA) as matrix liquids. The sample was applied by three different techniques; simple mixing, solvent mixing and surface precipitation. Smaller volumes of matrix liquid were found to produce more favourable ion currents. Detection limits were largely independent of the matrix or application technique used. The relationship between ion current and the mass of analyte was found to be intricately related to the choice of matrix liquid.
    • Fast atom bombardment mass spectrometry of the coordination complexes of the ligand 5, 5, 7, 12, 12, 14- hexamenthyl-1, 4, 8, 11-tetraazacycloteradecane

      MacLaurin, Cindy Lee.; Department of Chemistry (Brock University, 1985-07-09)
      A number of metal complexes containing the ligand 5,5,7,12,12,14-hexamethyl-l,4,8,11-tetra-azatetradecane were synthesized and analyzed using electron impact (EI) and fast atom bombardment (FAB). The FAB mass spectra were obtained in positive and negative ion mode. FAB in the positive ion mode proved to be the most successful technique for the identification of these compounds. In the majority of cases the spectra obtained using positive ion FAB were structurally informative, although not all showed molecular (M+) or quasimolecular ([M+H]+) ions. The fragmentations observed were characteristic of the ligands, and were interpreted based on the chemistry of these compounds.
    • Fast atom bombardment mass spectrometry studies of ruthenium (II) polypyridy coordination complexes and of group V Triptycenes and related complexes

      Nye, Jeffrey W.; Department of Chemistry (Brock University, 1986-07-09)
      In order to investigate the use of Fast Atom Bombardment Mass Spectrometry (FAB-MS) as a tool for structural characterization, two groups of complexes are analyzed. The first group is a set of ruthenium(II) coordination complexes containing bidentate polypyridyl ligands. The positive and negative ion FAB-MS spectra are found to be sufficient to allow for an almost complete characterization of the central metal atom, the ligands and the counter anions contained in the intact complex. An unusual observation of mUltiply charged ions in the positive ion FAB-MS spectra (i.e. [RUL 3 ]2+) is explained to be as a result of the oxidative quenching of the excited state of the doubly charged ion by the matrix, 3-nitrobenzyl alcohol. An analysis of a mixture shows that the technique is a good one for identifying components therein. A group of triptycene and related complexes containing Group V elements is also analyzed by FAB-MS and the results. in terms of relative abundances of fragment ions, are found to be consistent with known metal-carbon bond strengths.
    • A fast atom bombardment mass spectrometry study of tris (3, 6-dioxaheptyl) amine-alkali metal halide complexes and hydrogen bonded complexes

      Théberge, Roger.; Department of Chemistry (Brock University, 1987-07-09)
      The objective of this thesis was to demonstrate the potential of fast atom bombardment mass spectrometry (FABMS) as a probe of condensed phase systems and its possible uses for the study of hydrogen bonding. FABMS was used to study three different systems. The first study was aimed at investigating the selectivity of the ligand tris(3,6-dioxaheptyl) amine (tdoha) for the alkali metal cations. FABMS results correlated well with infrared and nmr data. Systems where a crown ether competed with tdoha for a given alkali metal cation were also investigated by fast atom bombardment. The results were found to correlate with the cation affinity of tdoha and the ability of the crown ether to bind the cation. In the second and third studies, H-bonded systems were investigated. The imidazole-electron donor complexes were investigated and FABMS results showed the expected H-bond strength of the respective complexes. The effects of concentration, liquid matrix, water content, deuterium exchange, and pre-ionization of the complex were also investigated. In the third system investigated, the abundance of the diphenyl sulfone-ammonium salt complexes (presumably H-bonded) in the FABMS spectrum were found to correlate with qualitative considerations such as steric hindrance and strength of ion pairs.
    • Flow injection analysis (FIA) determination of lead by hydride generation in banded coral skeletons /

      Tantreamjitmun, Napa.; Department of Chemistry (Brock University, 1997-05-21)
      A flow injection hydride generation direct current plasma atomic emission spectrometric (FI-HG-DCP-AES) method was developed for the determination of lead at ng.ml-l level. Potassium ferricyanide (K3Fe(CN)6) was used along with sodium tetrahydroborate(III) (NaBH4) to produce plumbane (PbH4) in an acid medium. The design of a gas-liquid separator (hydride generator) was tested and the parameters of the flow injection system were optimized to achieve a good detection limit and sample throughput. The technique developed gave a detection limit of 0.7 ng.ml-l(3ob). The precision at 20 ng.ml"* level was 1.6 % RSD with 1 1 measurements (n=l 1). Volume of sample loop was 500 |J.l. A sample throughput of 120 h"^ was achieved. The transition elements, Fe(II), FeOH), Cd(n), Co(II), Mn(n), Ni(II) and Zn(n) do not interfere in this method but 1 mg,l'l Cu(II) will suppress 50 % of the signal from a sample containing 20 ng.ml'l Pb. This method was successfully applied to determine lead in a calcium carbonate (CaC03) matrix of banded coral skeletons from Si-Chang Island in Thailand.
    • Fluorescence spectra and ab initio theoretical studies of HCOOH /

      Ioannoni, Francesca.; Department of Chemistry (Brock University, 1989-06-04)
      A fluorescence excitation spectrum of formic acid monomer (HCOOH) , has been recorded in the 278-246 nm region and has been attributed to an n >7r* electron promotion in the anti conformer. The S^< S^ electronic origins of the HCOOH/HCOOD/DCOOH/DCOOD isotopomers were assigned to weak bands observed at 37431.5/37461.5/37445.5/37479.3 cm'''. From a band contour analysis of the 0°^ band of HCOOH, the rotational constants for the excited state were estimated: A'=1.8619, B'=0.4073, and C'=0.3730 cm'\ Four vibrational modes, 1/3(0=0), j/^(0-C=0) , J/g(C-H^^^) and i/,(0-H^yJ were observed in the spectrum. The activity of the antisymmetric aldehyde wagging and hydroxyl torsional modes in forming progressions is central to the analysis, leading to the conclusion that the two hydrogens are distorted from the molecular plane, 0-C=0, in the upper S. state. Ab initio calculations were performed at the 6-3 IG* SCF level using the Gaussian 86 system of programs to aid in the vibrational assignments. The computations show that the potential surface which describes the low frequency OH torsion (twisting motion) and the CH wagging (molecular inversion) motions is complex in the S^ excited electronic state. The OH and CH bonds were calculated to be twisted with respect to the 0-C=0 molecular frame by 63.66 and 4 5.76 degrees, respectively. The calculations predicted the existence of the second (syn) rotamer which is 338 cm'^ above the equilibrium configuration with OH and CH angles displaced from the plane by 47.91 and 41.32 degrees.
    • Fluorometric monitoring of the properties of proteins entrapped in sol-gel derived matrices

      Flora, Kulwinder.; Department of Chemistry (Brock University, 1998-07-09)
      The successful development of stable biosensors incorporating entrapped proteins suffers from poor understanding of the properties of the entrapped biomolecules. This thesis reports on the use of fluorescence spectroscopy to investigate the properties of proteins entrapped in sol-gel processed silicate materials. Two different single tryptophan (Trp) proteins were investigated in this thesis, the Ca2 + binding protein cod III parvalbumin (C3P) and the salicylate binding protein human serum albumin (HSA). Furthermore, the reactive single cysteine (Cys) residue within C3P and HSA were labelled with the probes iodoacetoxynitrobenzoxadiazole (C3P) and acrylodan (C3P and HSA) to further examine the structure, stability and function of the free and entrapped proteins. The results show that both C3P and HSA can be successfully entrapped into sol-gelderived matrices with retention of function and conformational flexibility.
    • FT-IR and MAS NMR analysis of montmorillonite K10 supported MF2 reagents and their activity as catalysis /

      Asseid, Fathi M.; Department of Chemistry (Brock University, 1991-05-21)
      ZnF2, CdF2, and CUF2 have been adsorbed onto the surface of montmorillonite K10, and the infrared and 19F, 27 AI, and 29Si MAS NMR spectra of the reagents over a range of loadings have been obtained. CUF2 was observed to attack the Si02 layer and form the complex CuSiF6, Zn F2 tends to attack the aluminium oxide layer, in which Zn isomorphously replaces AI, and forms AIF3 and AIF4 - complexes. All the spectroscopic evidence ruled out the formation of any AI-F and/or Si-F free species as CdF2 is adsorbed on the surface of montmorillonite K10. The reactivity of MF2-K10 reagents towards Friedel-Crafts benzylation of benzene with benzyl chloride varied from one reagent to another. ZnF2-K10 was observed to be the most reactive and CUF2 was the least reactive.
    • A G. C./M. S. study of the reaction and decomposition products of pentafluorophenyl-grignard and lithium reagents

      Lin, Sechoing.; Department of Chemistry (Brock University, 1975-10-02)
      Decomposition and side reactions of, and the synthetic use of, pentafluorophenylmagnesium bromide and pentafluorophenyllithium have been investigated using G,C9/M.S, techniques• Their reactions with reagents such as CgF^X (X - H, F, CI, Br, 1), C6F4X2 (X - H, CI)f C6F3C13, C6H6. (CgX5)3P (X = H, F), (C6X5)3P=0 (X = H, F), (CgX5)Si (CH3)3 (X = H, F) and (CH0K SiCl , n = 1,2, in ether or ether/n-hexane were studied• In addition to the principal reaction of synthetic use, namely the replacement of a halogen by a pentafluorophenyl group, two types of side reactions were observed* These were (i) intermolecular loss of LiF via a nucleophilic substitution, and (ii) intramolecular loss of LiF, followed by the addition of either inorganic salts such as lithium or magnesium halides, or organometal compounds such as organolithium or organo-Grigaard* G.C«/M.S. techniques were routinely employed to study complicated reaction mixtures. Although mass spectrometry alone has disadvantages for the identification of isomers, deduction of the most probable pathway often helps overcome this problem.
    • Gas chromatographic electron capture negative ionization mass spectrometric (GC/ECNI/MS) determination of unique fluorinated compounds in the sediments of Lake Ontario and the effect of high-boiling alcohols (as injection solvents) on chromatographic behaviour of polycyclic aromatic hydrocarbons in gas chromatography

      Zielinski-Lawrence, Rosalie Krystyna.; Department of Chemistry (Brock University, 2009-01-28)
      Part I - Fluorinated Compounds A method has been developed for the extraction, concentration, and determination of two unique fluorinated compounds from the sediments of Lake Ontario. These compounds originated from a common industrial landfill, and have been carried to Lake Ontario by the Niagara River. Sediment samples from the Mississauga basin of Lake Ontario have been evaluated for these compounds and a depositional trend was established. The sediments were extracted by accelerated solvent extraction (ASE) and then underwent clean-up, fractionation, solvent exchange, and were concentrated by reduction under nitrogen gas. The concentrated extracts were analyzed by gas chromatography - electron capture negative ionization - mass spectrometry. The depositional profile determined here is reflective of the operation of the landfill and shows that these compounds are still found at concentrations well above background levels. These increased levels have been attributed to physical disturbances of previously deposited contaminated sediments, and probable continued leaching from the dumpsite. Part II - Polycyclic Aromatic Hydrocarbons Gas chromatography/mass spectrometry is the most common method for the determination of polycyclic aromatic hydrocarbons (PAHs) from various matrices. Mass discrimination of high-boiling compounds in gas chromatographic methods is well known. The use of high-boiling injection solvents shows substantial increase in the response of late-eluting peaks. These solvents have an increased efficiently in the transfer of solutes from the injector to the analytical column. The effect of I-butanol, I-pentanol, cyclopentanol, I-hexanol, toluene and n-octane, as injection solvents, was studied. Higher-boiling solvents yield increased response for all PAHs. I -Hexanol is the best solvent, in terms of P AH response, but in this solvent P AHs were more susceptible to chromatographic problems such as peak splitting and tailing. Toluene was found to be the most forgiving solvent in terms of peak symmetry and response. It offered the smallest discrepancies in response, and symmetry over a wide range of initial column temperatures.