A routine gas chromatographic method for the analysis of chlorofluorocarbons in aerosol cans

Summary A gas chromatographic (GC) method for the routine analysis of fully halogenated chlorofluorocarbons (CFCs) in aerosol cans is described. The identification of CFCs by GC was found to be in full agreement with those by GC-mass-spectrometery. The method has been applied to the analysis of CFCs in 448 aerosol products. The most commonly used fully halogenated CFC propellants in aerosol cans were found to be CFC11, CFC12 and CFC114.     

Sample preparation for gas chromatographic analysis of organic solvents in aerosol cans

Summary A method for the sampling of chemical products from aerosol cans is described. An aerosol can is frozen in liquid nitrogen, followed by puncturing the can and allowing the propellant to distill off. The conditions for the smaple preparation have been optimized. Solvent content in the products were analysed by headspace gas chromatography-mass spectrometry.     

Determination of chlorinated paraffins by GC-MS

Summary Although chlorinated paraffins are widely used and therefore produced in large amounts (about 250 kt/a) — with well known problems —, there is a lack of a selective, highly sensitive and reproducible analytical method for the determination of these substances. Such a method is presented using GC/MS with electron impact ionization for their quantitative determination. The samples, pretreated with conc. sulphuric acid, were cleaned up by solid-phase extraction on alumina, and the chlorinated paraffins were determined by GC/MS using highly selective ion clusters.By this method, determination limits of 3 ng (corresponding to about 1.5 ppb) were routinely obtained. In contrast to the general methods of maximum signal selection or the selection of molecule ions in mass spectroscopy, the presented approach leads to higher selectivity, less discrimination between different types of chlorinated paraffins and allows to obtain further information on the degree of chlorination.     

Gas chromatographic analysis of organic solvent mixtures on capillary columns of different polarity

Summary A gas chromatographic method for the analysis of organic solvents in chemical products is described. The analysis is performed by the use of a polar column, Supelcowax 10, and a non-polar column CP-Sil-5CB. Samples containing a non-volatile matrix or water were analysed by headspace analysis. The identification of the solvents in a sample, based on GC retention times on one column, is confirmed by GC of the sample on the second column. The method has been found to be suitable for the routine analysis of solvent mixtures.     

Analysis of nitrosamines in water by automated SPE and isotope dilution GC/HRMS Occurrence in the different steps of a drinking water treatment plant, and in chlorinated samples from a reservoir and a sewage treatment plant effluent

A method based on automated solid-phase extraction (SPE) and isotope dilution gas chromatography/high resolution mass spectrometry (GC/HRMS) has been developed for the analysis of nine nitrosamines in water samples. The combination of automated SPE and GC/HRMS for the analysis of nitrosamines has not been reported previously. The method shows as advantages the selectivity and sensitivity of GC/HRMS analysis and the high efficiency of automated SPE with coconut charcoal EPA 521 cartridges. Low method detection limits (MDLs) were achieved, along with a greater facility of the procedure and less dependance on the operator with regard to the methods based on manual SPE. Quality requirements for isotope dilution-based methods were accomplished for most analysed nitrosamines, regarding to trueness (80–120%), method precision (<15%) and MDLs (0.08–1.7 ng/L).Nineteen water samples (16 samples from a drinking water treatment plant {DWTP}, 2 chlorinated samples from a sewage treatment plant {STP} effluent, and 1 chlorinated sample from a reservoir) were analysed. Concentrations of nitrosamines in the STP effluent were 309.4 and 730.2 ng/L, being higher when higher doses of chlorine were applied. N-Nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) were the main compounds identified in the STP effluent, and NDEA was detected above 200 ng/L, regulatory level for NDMA in effluents stated in Ontario (Canada). Lower concentrations of nitrosamines were found in the reservoir (20.3 ng/L) and in the DWTP samples (n.d. −28.6 ng/L). NDMA and NDEA were respectively found in the reservoir and in treated and highly chlorinated DWTP samples at concentrations above 10 ng/L (guide value established in different countries). The highest concentrations of nitrosamines were found after chlorination and ozonation processes (ozonated, treated and highly chlorinated water) in DWTP samples.     

Determination of cholesterol in milk fat by gas chromatography with direct injection and sample saponification

Summary A rapid and direct gas chromatographic (GC) method for determining free cholesterol in milk fat using a capillary column and programmed-temperature vaporizerinjector was assayed. It was compared with other procedures involving saponification of fat, solvent extraction of unsaponifiable matter—with and without fractionation by thin-layer chromatography—and transformation of sterols into silyl derivatives prior to GC analysis. This paper proposes an alternative to other published procedures. Repeatability of the method was assessed and the coefficient of variation determined as 2.1%. The alternative saponification method exhibited comparable accuracy (coefficient of variation=1.8%). Recovery ranged from 99.1% to 105.6%.     

Monitoring and evaluation of dechlorination processes using compound-specific chlorine isotope analysis

A simple, quick and sensitive method for the compound-specific stable chlorine isotope analysis of chlorinated solvents by conventional quadrupole gas chromatography/mass spectrometry (GC/MS) is presented. With this method, compound-specific stable chlorine isotope ratios of typical chlorinated solvents like tetrachloroethene (PCE) and trichloroethene (TCE) can be determined quantitatively within 30 min by direct injection. The chlorine isotope ratios of target substances are calculated from the peak areas of several selected molecular ions and fragment ions of the substances, using a set of unique mathematical equations. The precision of the method was demonstrated through reproducibility tests. An internal precision of +/-0.4 per thousand to +/-1.1 per thousand was obtained when analyzing PCE and TCE in the 10-1000 pmol range. The validity of the method was further demonstrated by determining the chlorine isotopic fractionation factor during the reductive dechlorination of TCE in a batch experiment using zero-valent iron. The chlorine isotopic fractionation factor was calculated as 0.9976 +/- 0.0011 with a correlation coefficient of 0.9469 (n = 38). The high correlation coefficient indicates that compound-specific stable chlorine isotope analysis can be performed with sufficient accuracy using conventional quadrupole GC/MS when significant fractionation takes place during a reaction. For the first time, the chlorine isotope fractionation factor of TCE during an abiotic anaerobic dechlorination process was determined using quadrupole GC/MS, without offline sample preparation.     

A review of: “Handbook of Derivatives for Chromatography. K. Blau and G. S. King (editors). Heyden Publishers,London, Bellmawr,N.J., Rheine, 1977. xvi f 576 pages. Price £24.00: U.S.A. $48.0: DM 154.00.”

Abstract

Urban particulate matter, collected from Washington, DC and certified by the National Institute of Standards and Technology (NIST) as Standard Reference Material 1649, was extracted and fractionated into acid, base and neutral fractions. Each fraction was tested for biological activity using a microbial mutagenesis assay system. The organic acid fraction showed unexpectedly high mutagenic activity, and was subjected to chemical characterization studies. Following derivatization, analysis by GC/MS showed the presence of fatty acids, aromatic acids (including phenolic compounds), and a significant number of compounds that could not be identified from mass spectral compendia. Spectroscopic and elemental analysis data supported the characterization of the fraction as predominantly aromatic. Mass spectra from both GC/MS and direct probe analysis showed the presence of a chlorinated substance, subsequently identified as the fungicide Dichlorophen. The compound was shown to comprise over 50% of the mass of the organic acid fraction. A reference standard of Dichlorophen was not mutagenic. The presence of the fungicide in the NIST certified urban aerosol is, in all probability, due to artifactual processes. Attempts to concentrate the observed mutagenic activity by preparative chromatography and acid/base partition experiments were not successful.     

气相色谱-质谱法同时测定化妆品中18种氯代烃类有机溶剂

建立了同时测定化妆品中18种氯代烃类有机溶剂的气相色谱-质谱(GC-MS)检测方法.样品在饱和氯化钠溶液中由正十四烷振荡提取后,以Agilent J&W DB-624超高惰性毛细管柱(30m×0.25 mm×1.4μm)为分离色谱柱进行分析,以电子轰击(EI)源、SIM模式进行质谱监测,外标法定量.结果 表明,18种化...     

Identification of ω-oxocarboxylic acids as acetal esters in aerosols using capillary gas chromatography-mass spectrometry

An homologous series of ω,ω-dimethoxycarboxylic acid methyl esters (acetal esters) has been identified in the most polar methyl ester fraction separated from remote aerosol samples by liquid chromatography. These compounds were separated by silica gel column chromatography and their structures determined by capillary gas chromatography (GC) and GC—mass spectrometry with a synthesized standard. The acetal esters are originally present in the samples as ω-oxocarboxylic acids, which are derivatized to acetal esters during treatment with boron trifluoride in methanol. This method enables the determination of ω-oxocarboxylic acids in environmental samples as their acetal esters.     

Identification of solvents of abuse using gas chromatography/Fourier transform infrared spectrometry after headspace sampling

Summary After experimental intoxication of rats, gas chromatography — Fourier transform infrared spectrometry with headspace sampling (HS/GC/FT-IR) was used to identify solvents of abuse in biological material (blood, liver, lungs and brain). Limits of detection were measured for acetone, 2-butanone, ether, toluene and trichlorethylene with standard solutions. All the solvents have been identified in the organs of the intoxicated rats. For blood samples a salting-out effect was obtained with potassium carbonate. HS/GC/FT-IR allowed the identification of metabolites of acetone (isopropanol) and of 2-butanone (2-butanol) in blood and organs.     

Identification of natural dyes used in works of art by pyrolysis–gas chromatography/mass spectrometry combined with in situ trimethylsilylation

Samples of four natural dyes from different organic families—natural madder (anthraquinonoid), curcuma (curcuminoid), saffron (carotenoid) and indigo (indigotic)—were analysed using a new procedure based on pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS), which includes the on-line derivatisation of the natural dyes using hexamethyldisilazane (HMDS). In addition, a previous procedure involving the addition of a 10% H₂SO₄ aqueous solution to the dye and further separation with ethyl acetate has been tested. This procedure enhances the sensitivity of the method by extracting the colouring compounds from the rest of the compounds present in the natural dye. Two possible derivatising reagents—HMDS and tetramethylammonium hydroxide (TMAH)—were compared in order to assess their effectiveness in the proposed method. Characteristic peaks from trimethylsilyl derivatives of alizarin, quinizarin, xanthopurpurin and purpurin were obtained for madder; peaks from safranal, isophorone and trimethylsilyl derivative of crocetin for saffron; peaks from 4-(4-hydroxy-3-methoxy)phenyl-3-buten-2-one and 4-(4-hydroxy-3-methoxy)phenyl-2-butanone, which are primary pyrolysis products of curcuma, and peaks from indole, 2-methylindole and 2,3-dihydroindol-2-one, which are primary pyrolysis products of indigo, among others, were obtained. The reported procedure leads to the unambiguous identification of the four studied dyes from solid samples formed by individual dyes.Electronic Supplementary Material Supplementary material is available for this article at     

Determination of residual solvents in bulk pharmaceuticals by thermal desorption/gas chromatography/mass spectrometry

Thermal desorption (TD) techniques followed by capillary GC/MS were applied for the analysis of residual solvents in bulk pharmaceuticals. Solvents desorbed from samples by heating were cryofocused at the head of a capillary column prior to GC/MS analysis. This method requires a very small amount of sample and no sample pretreatment. Desorption temperature was set at the point about 20 degrees C higher than the melting point of each sample individually. The relative standard deviations of this method tested by performing six consecutive analyses of 8 different samples were 1.1 to 3.1%, and analytical results of residual solvents were in agreement with those obtained by direct injection of N,N-dimethylformamide solution of the samples into the GC. This novel TD/GC/MS method was demonstrated to be very useful for the identification and quantification of residual solvents in bulk pharmaceuticals.     

Methods for the isolation and characterization of constituents of natural products : XXI. Use of a celite-potassium methylate column for rapid preparation of methyl esters from microgram amounts of glycerides

In a convenient, rapid procedure, a very small column of potassium methylate — Hyflo Super-Cel is used to convert microgram amounts of glycerides to methyl esters. Transesterification is complete in hydrocarbon but not in chlorinated solvents or in CS₂. The methyl esters can be recovered in 92–95% yield if desired. Regardless of the solvent used, the recovered methyl esters are representative of the original fatty acid composition of the glycerides.     

Determination of chlorinated paraffins in cutting fluids and lubricants

An analytical routine procedure to classify chlorinated paraffins in technical products such as cutting fluids and lubricants is presented. Classification is based on chain length and chlorination degree (short chain, highly chlorinated congeners being subject to legal restrictions). After sample clean up with solid phase extraction over silica, screening is performed with gas chromatography and electron capture detection (ECD). Positive identification and quantitation is then performed with gas chromatography/mass spectrometry using negative chemical ionisation (NCI). Both methods show good reproducibility and repeatability and the average recovery of the chlorinated paraffins with the NCI method is 98%. The detection limits for restricted paraffins in samples range between 0.02–0.08% (w/w) for the ECD method and between 0.2–2.6% (w/w) for the NCI method. The procedure has been applied successfully to the analysis of 37 cutting fluids or lubricants. Short chain, highly chlorinated paraffins were detected in 8 (21%) samples in concentrations from 1 to 70% (w/w). The described procedure can be recommended as an analytical routine method for supervising future legal restrictions on the use of chlorinated paraffins in cutting fluids and lubricants. Received: 13 January 1997 / Revised: 20 March 1997 / Accepted: 3 April 1997     

Determination of chlorinated paraffins in cutting fluids and lubricants

An analytical routine procedure to classify chlorinated paraffins in technical products such as cutting fluids and lubricants is presented. Classification is based on chain length and chlorination degree (short chain, highly chlorinated congeners being subject to legal restrictions). After sample clean up with solid phase extraction over silica, screening is performed with gas chromatography and electron capture detection (ECD). Positive identification and quantitation is then performed with gas chromatography/mass spectrometry using negative chemical ionisation (NCI). Both methods show good reproducibility and repeatability and the average recovery of the chlorinated paraffins with the NCI method is 98%. The detection limits for restricted paraffins in samples range between 0.02–0.08% (w/w) for the ECD method and between 0.2–2.6% (w/w) for the NCI method. The procedure has been applied successfully to the analysis of 37 cutting fluids or lubricants. Short chain, highly chlorinated paraffins were detected in 8 (21%) samples in concentrations from 1 to 70% (w/w). The described procedure can be recommended as an analytical routine method for supervising future legal restrictions on the use of chlorinated paraffins in cutting fluids and lubricants. Received: 13 January 1997 / Revised: 20 March 1997 / Accepted: 3 April 1997     

Isolation of free phenolic compounds from arboreal leaves by use of the Florisil/C<Subscript>18</Subscript> system

In studies of the phenolic compounds present in leaves and needles, GC and GC–MS have so far been applied only sporadically. This is probably because of the greater difficulties encountered in preparing the samples for this method than those used for liquid chromatography. When preparing a sample for gas chromatography the analyst is faced with two difficult stages—separation of the compound from the matrix without losses (stage 1) so that the final sample can be derivatized to make it suitable for analysis on a non-polar capillary column of the gas chromatograph (stage 2). This paper presents a procedure for extraction of phenolic compounds from the matrix by means of a Florisil/C₁₈ sorbent system and their analysis by GC. After passage through the adsorbents the recovery ranges from 32% for ferulic acid to 88% for gentisic acid. It was found that this extraction method and the GC analysis are very precise (particularly for samples of a mass <1 g) and can be used for quantification. The high-precision quantification of 15 phenolic acids, shikimic acid, and six other compounds present in pine needles has been achieved. The conditions used for GC analysis and construction of calibration curves for quantitative determination are given.     

Alkyl methylphosphonic acids,the degradation products of organophosphorous CWA — preparation and direct quantitative GC-FID analysis

Seven alkyl methylphosphonic acids, products of hydrolytic degradation of organophosphorus chemical warfare agents, were obtained with a high purity (mostly above 98%), with the aim of being applyed as future certified reference materials. Ethyl (EMPA), isopropyl (IMPA), pinacolyl (PMPA), butyl (BUMPA), isobutyl (IBUMPA), cyclohexyl (CHMPA) and 2-ethylhexyl (EHMPA) monoesters of MPA were synthesized and characterized by MS EI, FTIR and NMR (¹H, ¹³C, ³¹P), TLC, as well as GC and GC-MS after derivatization. The conditions for a direct quantitative GC FID analysis on CP-FFAP CB column of non-derivatized alkyl methylphosphonic acids were developed. This is the first successful attempt of a directed GC analysis of free alkyl phosphonic acids. Their chemical purity was determined and limit of quantification (LOQ) values for some of them were evaluated for the GC-FID method.     

Rapid screening of selective serotonin re-uptake inhibitors in urine samples using solid-phase microextraction gas chromatography–mass spectrometry

In this paper a solid-phase microextraction–gas chromatography–mass spectrometry (SPME–GC–MS) method is proposed for a rapid analysis of some frequently prescribed selective serotonin re-uptake inhibitors (SSRI)—venlafaxine, fluvoxamine, mirtazapine, fluoxetine, citalopram, and sertraline—in urine samples. The SPME-based method enables simultaneous determination of the target SSRI after simple in-situ derivatization of some of the target compounds. Calibration curves in water and in urine were validated and statistically compared. This revealed the absence of matrix effect and, in consequence, the possibility of quantifying SSRI in urine samples by external water calibration. Intra-day and inter-day precision was satisfactory for all the target compounds (relative standard deviation, RSD, <14%) and the detection limits achieved were <0.4 ng mL^–1 urine. The time required for the SPME step and for GC analysis (30 min each) enables high throughput. The method was applied to real urine samples from different patients being treated with some of these pharmaceuticals. Some SSRI metabolites were also detected and tentatively identified.