An improved thin-layer chromatography/mass spectrometry coupling using a surface sampling probe electrospray ion trap system

A combined surface sampling probe/electrospray emitter coupled with an ion trap mass spectrometer was used for the direct read out of unmodified reversed-phase C18 thin-layer chromatography (TLC) plates. The operation of the surface sampling electrospray ionization interface in positive and negative ionization modes was demonstrated through the direct analysis of TLC plates on which a commercial test mix comprised of four dye compounds viz., rhodamine B, fluorescein, naphthol blue black, and fast green FCF, and an extract of the caffeine-containing plant Ilex vomitoria, were spotted and developed. Acquisition of full-scan mass spectra and automated collection of MS/MS product ion spectra while scanning a development lane along the surface of a TLC plate demonstrated the advantages of using an ion trap in this combination. Details of the sampling system, benefits of analyzing a developed lane in both positive ion and negative ion modes, levels of detection while surface scanning, surface scan speed effects, and the utility of three-dimensional data display, are also discussed.

Structural determination of subsidiary colors in commercial Food Green No. 3 (fast green FCF, FD & C Green No. 3)

HPLC analysis revealed that eight subsidiary colors existed in commercial Food Green No. 3 (fast green FCF, FD & C Green No. 3). Among them, four subsidiary colors C, F, G, and H were isolated by using preparative HPLC and their structures were determined by MS and NMR. They were the disodium salt of 2-[[4-[N-ethyl-N-(3- sulfophenylmethyl)amino]phenyl][4-[N-ethyl-N-(4- sulfophenylmethyl)amino]phenyl]methylio]-4-hydroxybenzenesulfonic acid (abbreviated as m,p-G-3), the sodium salt of 2-[[(4-N-ethylamino)phenyl][4-[N-ethyl-N-(3- sulfophenylmethyl)amino]-phenyl]methylio]-4-hydroxybenzenesulfonic acid [abbreviated as HSBA-(EA) (m-EBASA)], the sodium salt of 2-[[(4-N-diethylamino)phenyl][4-[N-ethyl-N-(3- sulfophenylmethyl)amino]phenyl]-methylio]-4-hydroxybenzenesulfonic acid [abbreviated as HSBA-(di-EA) (m-EBASA)], and the sodium salt of 2-[[4-[N-ethyl-N-(phenylmethyl)amino]phenyl][4-[N-ethyl-N-(3- sulfophenylmethyl)-amino]phenyl]methylio]-4-hydroxybenzenesulfonic acid [abbreviated as HSBA-(EBA)(m-EBASA)], respectively. HSBA-(di-EA) (m-EBASA) was a subsidiary color newly found in commercial Food Green No. 3.

[Studies on "Fast Green FCF Standard" for the dye standard on the National Institute of Health Sciences]

The raw material for Fast Green FCF was tested for preparation of the "Fast Green FCF Standard (C.I. 42053)". Analytical data obtained were as follows: paper chromatography, only one spot is observed; arsenic content, 0.38 microgram/g; chloride content, 0.11%; sulfate content, 3.30%; heavy metals, lead, 8.0 micrograms/g, manganese, 28.1 micrograms/g, and chromium, 1.6 micrograms/g; infrared spectra, 1575 cm-1, 1169 cm-1, and 1033 cm-1; loss on drying, 2.39%; assay, 93.0% by the titanium trichloride titration. Based on the above results, the raw material was authorized as the Dye Standard of National Institute of Health Sciences.

Effect of host age on microenvironmental heterogeneity and efficacy of combined modality therapy in solid tumors

The implications of microenvironmental heterogeneity in solid tumors for combined modality therapy were assessed by comparing the microenvironmental profiles and therapeutic responses of EMT6 tumors implanted into young and aging mice. The radiobiological hypoxic fraction of tumors in aging mice was shown to be 41% (95% CL, 28-60%), while that in young adult hosts is 19% (95% CL, 14-25%). These microenvironmental differences were also seen in perfusion studies and in studies of the intratumoral pH and pO2 in young and aging mice. The therapeutic importance of microenvironmental factors can be examined in this system, as the tumor cells per se are identical, but the proportions of tumor cells in adverse microenvironments are different. Studies described here show that mitomycin C, an agent with selective toxicity to hypoxic cells, produced greater antineoplastic effects in tumors in aging mice when used alone or as an adjunct to radiation. Combined-modality regimens incorporating agents selectively toxic to hypoxic cells may be especially valuable in improving the results of radiotherapy in tumors in which the tumor-host interactions have resulted in unusually large hypoxic fractions.