Gas—liquid chromatographic analyses

Chemical Composition of Miscanthus sinensis var. purpurascens Flower Absolute and Its Beneficial Effects on Skin Wound Healing and Melanogenesis-Related Cell Activities

Miscanthus sinensis var. purpurascens (MSP, flame grass) is found in Korea, Japan, and China, and its biological activities include anti-cancer, detoxifying, vasodilatory, antipyretic, and diuretic effects. However, no study has investigated the effects of MSP on skin-related biological activities. In this study, we explored the effects of the absolute extracted from the MSP flowers (MSPFAb) on skin wound healing- and whitening-related responses in keratinocytes or melanocytes. MSPFAb contained 6 components and induced the proliferation, migration, and syntheses of type I and IV collagens in keratinocytes. MSPFAb also increased the phosphorylations of serine/threonine-specific protein kinase, p38 mitogen-activated protein kinase, and extracellular signal-regulated kinase1/2 in keratinocytes. In addition, treatment with MSPFAb decreased serum-induced melanoma cell proliferation and inhibited tyrosinase activity and melanin contents in α-MSH-stimulated melanoma cells. Taken together, this study indicates MSPFAb may promote wound healing- and whitening-associated activities in dermal cells, and suggests that it has potential use as a wound healing and skin whitening agent.

Comparison of a variety of gas chromatographic columns with different polarities for the separation of chlorinated dibenzo-p-dioxins and dibenzofurans by high-resolution mass spectrometry

The applicability of 13 different GC columns (Agilent HP-5MS, Restek Rtx-5MS, Rtx-Dioxin2, Supelco Equity 5, SP-2331, Varian VF-5MS, CP-Sil 8 CB LowBleed/MS, J&W Scientific DB-5, DB-225, DB-XLB, DB-5MS, Phenomenex ZB-5MS, and ZB-5UMS) for US Environmental Protection Agency (EPA) methods 1613b, 8290 and European Standard Method EN 1948 for measurement of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) has been evaluated for the separation of all International Toxic Equivalent Factor (I-TEF) isomers (tetra- through octachlorinated at 2,3,7,8 positions) from closely eluting isomers using high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). The relative performance data are compared based on mass chromatograms using a "visualization approach", absolute retention times, 2,3,7,8-substituted, total dioxins and furans concentrations, as well as TEQ comparisons. None of the columns tested were able to separate all 17 I-TEFs from other co-eluted isomers. Our data indicate that all I-TEFs isomers can be fully differentiated from closely eluting isomers using either of two sets of non-polar and polar stationary phase combinations. One set consists of DB-5 (HP-5MS, Rtx-5MS, Equity-5) and DB-225 GC columns and another set would have a combination of DB-5MS (ZB-5MS, VF-5MS, CP-Sil 8 CB LowBleed/MS) with SP-2331. However, depending on the source of PCDDs/PCDFs a laboratory could choose a single GC column that separates the 2,3,7,8-substituted congeners that contribute most significantly to the overall TEQ. These data are the most comprehensive to date, provide a valuable addition to operational criteria for the standard EPA methods 1613b, 8290, European Standard Method EN 1948 and will allow researches to compare data generated according to the different compliance analytical procedures.

Comparison of Series 5 gas chromatography column performances from a variety of manufacturers for separation of chlorinated dibenzo-p-dioxins and dibenzofurans using high-resolution mass spectrometry

An extended study of seven fused silica capillary gas chromatographic (GC) columns has been conducted with regard to separation of international toxic equivalent factor (I-TEF) isomers (tetra- through octa-chlorinated at 2,3,7,8 positions) of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/PCDFs) from closely co-eluted other isomers using high-resolution gas chromatography-high-resolution mass spectrometry (HRGC-HRMS). The data are explicated in mass chromatograms of Series 5 GC columns from a variety of manufacturers (Varian CP-Sil 8 CB LowBleed/MS, Phenomenex ZB-5UMS, Agilent HP-5MS, Restek Rtx-5MS, Supelco Equity-5, J&W Scientific DB-5 and DB-5MS), according to relative retention times, and 2,3,7,8-substituted isomer concentrations for each of the columns tested. Results showed differences between 5% phenyl methyl silicone and 5% silphenylene (Si-arylene) silicone polymer type GC stationary phases in separation of 2,3,7,8-substituted PCDDs/PCDFs from closely co-eluted isomers. The separation differences for Si-arylene type columns resulted in lower toxic equivalence (TEQ) values compared to the siloxane-based columns. Because of differences in product nomenclature and manufacturing practices by various manufacturers, incorrect assumptions and comparisons may be made regarding the interchangeability of these columns for PCCD/PCDF separations. The data presented are the most comprehensive to date and provide a valuable addition to operational criteria for the standard US Environmental Protection Agency methods 1613b and 8290.

Dependence of GC-RRTs on the electrical charge at substituents of chlorinated dioxins and related compounds

The correlation between gas chromatograph relative retention times (GC-RRTs) of polychlorinated dioxins and related compounds (PCBs, PCDDs, PCDFs, and PCNs) and descriptors calculated from the electrical charges at substituents, such as the sums of the charges at hydrogen atoms (QH), and chlorine atoms (QCl), and the sum of QH and QCl (Qall), was analyzed for their congeners and isomers. The dependence of GC-RRTs on these descriptors varied dramatically. For the congeners, there was an approximately linear relationship between GC-RRTs and all the descriptors. For the isomers, although there was little significant relationships, by classifying GC-RRTs based on Nad-Cl or Nad-H defined from the number of adjacent chlorine and hydrogen substituents, a linear relationship between GC-RRTs and QH was found for CBs, CDDs, and CDFs, and GC-RRTs for CNs could be classified. From an analysis of the electrical charges at hydrogen substitutents bonded to adjacent and non-adjacent positions, the average-charge of such substituents bonded to adjacent positions decreased with an increase in Nad-H, and this tendency was similar to that for bonding to ortho-, meta-, para-, alpha-, and beta-positions.

Dependence of GC-RRTs on the solvent-accessible surface area of dioxins and related compounds

The correlation between gas chromatograph relative retention times (GC-RRTs) of dioxins and related compounds, polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated naphthalenes (PCNs), and their solvent-accessible surface area (SAS) was analyzed for congeners and isomers. GC-RRTs were linearly dependent on SAS for congeners while there was little dependence for isomers. However, by using classification parameters, Nad-Cl, Nad-H, N1,9Cl, and NalphaCl, based on the substitution positions and patterns of chlorine and/or hydrogen atoms bound to the molecular skeleton, a linear relationship was found among isomers. Furthermore, the GC-RRTs of CDD, CDF, and CN isomers, which are planar, decreased despite increasing SAS, and this tendency was enhanced with the above classification. The retention behavior was explained in terms of the effective enhancement of molecular hydrophobicity caused by an increase in the number of adjacent chlorine pairs.