Determination of estrogens and progestogens by mass spectrometric techniques (GC/MS, LC/MS and LC/MS/MS)

Steroid sex hormones and related synthetic compounds have been shown to provoke alarming estrogenic effects in aquatic organisms, such as feminization, at very low concentrations (ng/L or pg/L). In this work, different chromatographic techniques, namely, gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS), are discussed for the analysis of estrogens, both free and conjugated, and progestogens, and the sensitivities achieved with the various techniques are inter-compared. GC/MS analyses are usually carried out after derivatization of the analytes with bis(trimethylsilyl)trifluoroacetamide (BSTFA). For LC/MS and LC/MS/MS analyses, different instruments, ionization techniques (electrospray (ESI) and atmospheric pressure chemical ionization (APCI)), ionization modes (negative ion (NI) and positive ion (PI)) and monitoring modes (selected ion monitoring (SIM) and selected reaction monitoring (SRM)) are generally employed. Based on sensitivity and selectivity, LC/ESI-MS/MS is generally the method of choice for determination of estrogens in the NI mode and of progestogens in the PI mode (instrumental detection limits (IDLs) 0.1-10 ng/mL). IDLs achieved by LC/ESI-MS in the SIM mode and by LC/ESI-MS/MS in the SRM mode were, in general, comparable, although the selectivity of the latter is significantly higher and essential to avoid false positive determinations in the analysis of real samples. Conclusions and future perspectives are outlined.     

Mass spectrometry applied to the analysis of estrogens in the environment

Environmental analytical chemistry has recently changed focus from analysis of non-polar, persistent contaminants (e.g. polychlorinated biphenyls and dioxins) to more polar and labile compounds that interfere with biological processes. For example, natural and synthetic estrogens and their metabolites have been detected in sewage treatment plant effluents at nanogram/liter concentrations that are similar to those at which both total sex reversal and intersex (containing both testes and ova) is induced in fish exposed to these compounds in laboratory experiments. The development of techniques for the analysis of natural and synthetic estrogens in biological fluids (i.e. serum and urine) has been a priority in the biomedical field. However, the recent recognition that estrogen hormones are contaminants in the environment that may contribute to endocrine disruption has focused attention on the need for highly sensitive and specific techniques that are applicable for trace analysis in complex environmental matrices. Three optimized mass spectrometric protocols have been developed for the determination and quantitation of steroid hormones in environmental matrices using gas chromatography/tandem mass spectrometry (GC/MS/MS), liquid chromatography/mass spectrometry selected ion monitoring, (LC/MS - SIM) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). The advantages and disadvantages of each method are presented.     

色谱／质谱联用技术分析测定贻贝中的多环芳烃

介绍了ＧＣ－ＭＳ联用技术－物质征离子选择法测定贻贝中多环芳烃的分析方法，并就定性定量离子的选择，以及方法的准确度和精密度进行了探讨。结果表明，本方法适用于海洋生物贻贝，牡蛎中ＰＡＨｓ的分析测定。     

Hyphenated mass spectrometric techniques-indispensable tools in clinical and forensic toxicology and in doping control

Hyphenated mass spectrometric techniques, particularly gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS), are indispensable tools in clinical and forensic toxicology and in doping control owing to their high sensitivity and specificity. They are used for screening, library-assisted identification and quantification of drugs, poisons and their metabolites, prerequisites for competent expertise in these fields. In addition, they allow the study of metabolism of new drugs or poisons as a basis for developing screening procedures in biological matrices, most notably in urine, or toxicological risk assessment. Concepts and procedures using GC/MS and LC/MS techniques in the areas of analytical toxicology and the role of mass spectral libraries are presented and discussed in this feature article. Finally, perspectives of their future position are discussed.     

Certified reference material for quantification of polycyclic aromatic hydrocarbons in sediment from the National Metrology Institute of Japan

The National Metrology Institute of Japan has issued a certified reference material (CRM) of freshwater lake sediment for polycyclic aromatic hydrocarbon (PAHs) analyses. The certification used three extraction techniques: pressurized liquid extraction (PLE) with toluene, PLE with dichloromethane/ethyl acetate (1:1 by volume), and alkaline extraction (1 M KOH in methanol) in combination with microwave-assisted extraction. Both gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/dopant-assisted atmospheric pressure photoionization/MS (LC/DA-APPI/MS) analyses were used. Certified values are provided for 18 PAHs at 1–25 μg kg⁻¹ except for perylene (2.08 × 10³ μg kg⁻¹), and information values are provided for two. Since the values of PAHs in the CRM are much lower than those in other CRMs and are comparable to those found at sites with little human influence, the CRM is suitable for PAH monitoring in sediment and soil samples.     

Enantiomeric fraction determination of chiral drugs in environmental samples using chiral liquid chromatography and mass spectrometry

When it was recognized that chiral drug residues have stereospecific toxicity towards environmental organisms the attention given to enantiomeric fraction determination of chiral drugs in the environment increased. Among various analytical techniques, chiral liquid chromatography (LC) coupled with mass spectrometry (MS) has been widely used due to its simplicity, wide applicability and high sensitivity. In this review, we aim to provide a comprehensive overview and comparison of the types of chiral stationary phases, elution modes and MS detection techniques employed and address the advances and limitations. The impact of the mobile phase composition on enantioseparation and MS detection are discussed based on the different methods developed. In addition, diverse applications for the enantiomeric fraction determination of chiral drugs in environmental matrices using chiral LC and MS are discussed in depth.     

Determination of nitrated-polyaromatic hydrocarbons (nitro-PAHs) in environmental samples by high resolution chromatographic techniques

An analytical procedure is described for the fractionation of organic compounds present in environmental samples and the determination of nitro polyaromatic hydrocarbons (nitro-PAHs). Both low and high resolution liquid chromatography are employed for the prefractionation of the soluble organic fraction (SOF) extracted from particulate matter or gaseous pollutants collected on adsorption traps. High resolution gas chromatography is used to analyze four fractions containing alkanes, PAHs, nitro-PAHs, and other polar PAHs. Nitrogen-containing species are separated by GC and detected specifically using an alkali flame (NPD) detector. Flame ionization (FID) detection, GC-MS of positive ions, and negative ion chemical ionization MS of the whole fraction is used for the identification and quantitation of the various components. The composition of SOF extracted from particulate matter emitted from diesel exhausts is elucidated and a large number of nitro-PAHs identified by the combination of the various techniques.     

Developments in the use of chromatographic techniques in marine laboratories for the determination of halogenated contaminants and polycyclic aromatic hydrocarbons

Chromatography has been an important tool in marine laboratories. Since the 1960s, marine laboratories have been involved in the analysis of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), and brominated flame retardants (BFRs). Column chromatography and liquid chromatography (LC) techniques have been used, mainly in the clean-up phase, while gas chromatography (GC) has been used extensively in the final determination of these contaminants. Developments have been observed from the use of packed GC columns, via capillary columns to the use of heart-cut multi-dimensional GC and comprehensive multi-dimensional GC. The progress made in interlaboratory studies and the availability of certified reference materials are discussed.     

Study on the photostability of guaiazulene by high-performance liquid chromatography/mass spectrometry and gas chromatography/mass spectrometry

The photostability of guaiazulene (1,4-dimethyl-7-isopropylazulene; GA), a natural azulenic compound used in cosmetic and health-care products, as well as in pharmaceutical preparations, was investigated in solution (methanol, ethanol, acetonitrile), by different techniques: gas chromatography/mass spectrometry (GC/MS) and high-performance liquid chromatography combined with atmospheric pressure chemical ionization mass spectrometry and UV detection (LC/APCI-MS and HPLC/UV). A solar simulator (xenon-arc lamp) was used as UV-A radiation source. The study involved: monitoring compound decomposition, identifying products of photodegradation (PPs), assessing the role of oxygen and evaluating the kinetics of the process. Minor PPs are volatile compounds and were characterized by GC/MS, while oligomeric polyoxygenated compounds, tentatively characterized on the basis of MS and MS/MS spectra, were found to be the main photoproducts. The photodegradation was found to be enhanced by the presence of oxygen; nevertheless, determination of the singlet oxygen quantum yield for GA gave a lower value than that for the reference standard Rose Bengal. The obtained results and the developed stability-indicating methods (GC/MS and LC/MS) are of interest for stability studies and/or quality control purposes of GA as raw material or cosmetic products.     

Two new marine sediment standard reference materials (SRMs) for the determination of organic contaminants

Two new marine sediment standard reference materials (SRMs), SRM 1941b Organics in Marine Sediment and SRM 1944 New York/New Jersey Waterway Sediment, have been recently issued by the National Institute of Standards and Technology (NIST) for the determination of organic contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCB) congeners, and chlorinated pesticides. Both sediment SRMs were analyzed using multiple analytical methods including gas chromatography/mass spectrometry (GC/MS) on columns with different selectivity, reversed-phase liquid chromatography with fluorescence detection (for PAHs only), and GC with electron capture detection (for PCBs and pesticides only). SRM 1941b has certified concentrations for 24 PAHs, 29 PCB congeners, and 7 pesticides, and SRM 1944 has certified concentrations for 24 PAHs, 29 PCB congeners, and 4 pesticides. Reference concentrations are also provided for an additional 58 (SRM 1941b) and 39 (SRM 1944) PAHs, PCB congeners, and pesticides. SRM 1944, which was collected from multiple sites within New York/New Jersey coastal waterways, has contaminant concentrations that are generally a factor of 10–20 greater than SRM 1941b, which was collected in the Baltimore (Maryland) harbor. These two SRMs represent the most extensively characterized marine sediment certified reference materials available for the determination of organic contaminants.Electronic Supplementary Material Supplementary material is available in the online version of this article at . A link in the frame on the left on that page takes you directly to the supplementary material.     

Preparation and certification of two freshwater sediments certified reference materials for polycyclic aromatic hydrocarbons

Two freshwater sediments certified reference materials (CRMs) for 16 polycyclic aromatic hydrocarbons (PAHs) have been developed by the Institute for Environmental Reference Materials (IERM) of Ministry of Environmental Protection (MEP) in China. The methodology for preparing the CRMs of PAHs in sediments is described in this paper. The collected natural sediment samples were air-dried, ground, homogenised, packed, sterilised and tested on stability and homogeneity. Homogeneity results showed that the between-unit variation was confirmed to be below 4.5% for each compound. Stability was assessed after storage of samples for 16 months at temperature less than 30°C and in shade. The certification of the natural sediment matrix CRMs for PAHs was based on the agreement of results using different analytical techniques including gas chromatography/mass spectrometry (GC/MS) and reversed-phase liquid chromatography (LC) by no less than eight collaborating laboratories including IERM. Results of the homogeneity showed that the calculated u_bb′ was 0.9–2.5% for environmental river standard-4 (ERS-4) and 9–2.3% for environmental lake standard-1 (ELS-1), whereas stability results of total 16 PAHs indicated that the calculated u_rel,lts was 4.2% for ERS-4 and 2.2% for ELS-1. Certified values of 16 PAHs in ERS-4 varied from 8.5 to 167 μg/kg and ranged from 0.036 to 2.8 mg/kg in ELS-1.The good comparability, together with the independent confirmation of the assigned mass fraction by using different methods, confirmed that the CRMs are suitable for the method validation and quality control in soil or sediments analysis.     

Trace-level determination of pesticides in water by means of liquid and gas chromatography

The trace-level determination of pesticides and their transformation products (TPs) in water by means of liquid and gas chromatography (LC and GC) is reviewed. Special attention is given to the use of (tandem) mass spectrometry for identification and confirmation purposes. The complementarity of LC- and GC-based techniques and the potential of comprehensive GC×GC are discussed, and also the impressive performance of time-of-flight mass spectrometry. It is also indicated that, in the near future, the TPs rather than the parent compounds should receive most attention—with a better understanding of matrix effects and eluent composition on the ionization efficiency of analytes being urgently required. Finally, the merits of using much shorter LC columns, or even no column at all (flow-injection analysis) in target analysis are shown, and a more cost-efficient and sophisticated strategy for monitoring programmes is briefly introduced.     

Comparison of gas chromatography and liquid chromatography mass spectrometric measurements for high accuracy analysis of cholesterol in human serum by isotope dilution mass spectrometry

Cholesterol measurements are of vital clinical importance and reliable reference materials are essential for method validation. Gas chromatography with mass spectrometry (GC/MS) is usually used for the high accuracy analysis of cholesterol by isotope dilution. A certified reference material for cholesterol content in human serum was analysed by isotope dilution utilising GC/MS and liquid chromatography mass spectrometry (LC/MS). The use of LC/MS avoided the need for a derivatisation step. Both LC/MS and GC/MS produced results on the measurement of cholesterol that agreed within 0.5% of the certified value. Moreover, the precision obtained for ratio measurement using both techniques are comparable and lead to relative expanded standard uncertainties (with a coverage factor of 2) varying between 0.2 and 0.5%.     

Analysis of turkish lignite tar by coupled LC/GC,GC/MS,and capillary SFC

This work describes the analysis of a pyrolysis product of a lignite sample obtained from the Turkish Goynuk reserve. The aliphatic, aromatic and polar compounds present in the tar are separated and identified by various chromatographic techniques: Capillary gas chromatography/mass spectrometry (GC/MS), on-line high performance microbore liquid chromatography/capillary gas chromatography (LC/GC) and capillary supercritical fluid chromatography (SFC). The suitability of each technique for this particular application is discussed, and semi-quantitative results are presented for the major components detected.     

Review of the QuEChERS method for the analysis of organic pollutants: Persistent organic pollutants,polycyclic aromatic hydrocarbons,and pharmaceuticals

In multi-residue pesticide analysis, the quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method has replaced less efficient traditional extraction methods due to its many advantages. In addition to pesticide analysis, this method has been widely used for the detection and analysis of pharmaceuticals, polycyclic aromatic hydrocarbons (PAHs), and several persistent organic pollutants (POPs), including dioxins, polychlorinated biphenyls, perfluoroalkyl substances, and brominated flame retardants in food, biological, and environmental matrices. The analysis of PAHs and POPs is challenging due to the properties of the target compounds and their low concentrations in complex matrices. This review summarizes previously reported the QuEChERS extraction approaches to the analysis of a wide range of analytes. The QuEChERS approaches, which include dispersive solid phase extraction (d-SPE), have generally been combined with either gas chromatography–mass spectrometry (GC–MS) or liquid chromatography–mass spectrometry (LC–MS) analysis. Further on, in recent years, GC and LC-tandem mass spectrometry has been utilized with the QuEChERS extraction due to its high selectivity, sensitivity, and specificity. This enables the extraction methods for target analytes to be modified through the selection of different extraction solvents, salt formulations, and buffers for salting-out partitioning and the selection of different d-SPE and SPE sorbents for the clean-up process. The most significant advantage of this method is that concentration steps are not required. This review aims to provide an up-to-date overview of information regarding the modification of extraction techniques based on target compounds and sample matrices.     

Characterisation of middle-distillates by comprehensive two-dimensional gas chromatography (GC x GC): A powerful alternative for performing various standard analysis of middle-distillates

The detailed characterisation of middle distillates is essential for a better understanding of reactions involved in refining process. Owing to higher resolution power and enhanced sensitivity, comprehensive two-dimensional gas chromatography (GC x GC) is a powerful tool for improving characterisation of petroleum samples. The aim of this paper is to compare GC x GC and various ASTM methods -- gas chromatography (GC), liquid chromatography (LC) and mass spectrometry (MS) -- for group type separation and detailed hydrocarbon analysis. Best features of GC x GC are demonstrated and compared to these techniques in terms of cost, time consumption and accuracy. In particular, a new approach of simulated distillation (SimDis-GC x GC) is proposed: compared to the standard method ASTM D2887 it gives unequal information for better understanding of conversion process.     

Liquid chromatography/negative ion atmospheric pressure photoionization mass spectrometry: a highly sensitive method for the analysis of organic explosives

Gas chromatography/mass spectrometry (GC/MS) is applied to the analysis of volatile and thermally stable compounds, while liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI‐MS) and liquid chromatography/electrospray ionization mass spectrometry (LC/ESI‐MS) are preferred for the analysis of compounds with solution acid‐base chemistry. Because organic explosives are compounds with low polarity and some of them are thermally labile, they have not been very well analyzed by GC/MS, LC/APCI‐MS and LC/ESI‐MS. Herein, we demonstrate liquid chromatography/negative ion atmospheric pressure photoionization mass spectrometry (LC/NI‐APPI‐MS) as a novel and highly sensitive method for their analysis. Using LC/NI‐APPI‐MS, limits of quantification (LOQs) of nitroaromatics and nitramines down to the middle pg range have been achieved in full MS scan mode, which are approximately one order to two orders magnitude lower than those previously reported using GC/MS or LC/APCI‐MS. The calibration dynamic ranges achieved by LC/NI‐APPI‐MS are also wider than those using GC/MS and LC/APCI‐MS. The reproducibility of LC/NI‐APPI‐MS is also very reliable, with the intraday and interday variabilities by coefficient of variation (CV) of 0.2–3.4% and 0.6–1.9% for 2,4,6‐trinitrotoluene (2,4,6‐TNT). Copyright © 2008 John Wiley & Sons, Ltd.     

Determination of two oxy-pyrimidine metabolites of diazinon in urine by gas chromatography/mass selective detection and liquid chromatography/electrospray ionization/mass spectrometry/mass spectrometry

An analytical method was developed for the determination in urine of 2 metabolites of diazinon: 6-methyl-2-(1-methylethyl)-4(1H)-pyrimidinone (G-27550) and 2-(1-hydroxy-1-methylethyl)-6-methyl-4(1H)-pyrimidinone (GS-31144). Two of the urine sample preparation procedures presented rely on gas chromatography/mass selective detection (GC/MSD) in the selected ion monitoring mode for determination of G-27550. For fast sample preparation and a limit of quantitation (LOQ) of 1.0 ppb, urine samples were purified by using ENV+ solid-phase extraction (SPE) columns. For analyte confirmation at an LOQ of 0.50 ppb, classical liquid/liquid partitioning was used before further purification in a silica SPE column. An SPE sample preparation procedure and liquid chromatography/electrospray ionization/mass spectrometry/mass spectrometry (LC/ESI/MS/MS) were used for both G-27550 and GS-31144. The limit of detection was 0.01 ng for G-27550 with GC/MSD, and 0.016 ng when LC/ESI/MS/MS was used for both G-27550 and GS-31144. The LOQ was 0.50 ppb for G-27550 when GC/MSD and the partitioning/SPE sample preparation procedure were used, and 1.0 ppb for the SPE only sample preparation procedure. The LOQ was 1.0 ppb for both analytes when LC/ESI/MS/MS was used.     

Polycyclic aromatic hydrocarbons (PAHs) pollution recorded in annual rings of gingko (Gingko biloba L.): Determination of PAHs by GC/MS after accelerated solvent extraction

Retrospective monitoring of polycyclic aromatic hydrocarbons (PAHs) pollution levels was demonstrated by analyzing the annual rings of gingko (Gingko biloba L.) sampled from the Chengdu plain of southwest China. The samples of gingko trunk section, leaf, bark and its host soil were analyzed for PAHs by gas chromatography/mass spectrometry (GC/MS) after optimized accelerated solvent extraction (ASE). Compared to ultrasonic or soxhlet, ASE has high extraction efficiency thus meaningful contamination information contained in trunk tissue. The distribution of PAHs in gingko trunk, leaf and its host soil indicates that the main uptake pathway might be gaseous and particles-bound deposition via foliage with the exception of two-ring compounds from root, such as Nap and 2-methyl-Nap. PAHs in gingko trunk could be used to reveal the regional and historical contamination information, which is consistent with the environmental history of events (straw incineration) in Chengdu.     

LC–MS/MS in the routine clinical laboratory: has its time come?

Liquid chromatography–tandem mass spectrometry (LC–MS/MS) has been increasingly used in routine clinical laboratories during the last two decades. The high specificity, sensitivity, and multi-analyte potential make it an ideal alternative to immunoassays or conventional high-performance liquid chromatography (HPLC). It also provides higher throughput than gas chromatography–mass spectrometry (GC–MS). LC–MS/MS also offers higher flexibility than immunoassays because LC–MS/MS assays are typically developed in-house. In addition, abundant information can be obtained from a single LC–MS/MS run which can produce a large amount of quantitative or qualitative data. In this review, typical LC–MS/MS clinical applications are presented, personal experiences are shared, and strengths and weakness are discussed. It is foreseeable that LC–MS/MS will become a key instrument in routine clinical laboratories.