Advanced high-performance liquid chromatography method for highly polar nitroaromatic compounds in ground water samples from ammunition waste sites

An advanced HPLC-photodiode array detection method for the determination of 12 selected highly polar nitroaromatic compounds in ground water samples of ammunition waste sites has been developed and validated. After solid-phase extraction the limits of detection were in the range 0.1–0.5 μg/l. To prove the applicability of the method to other polar nitroaromatic compounds the retention time of another 32 polar compounds under the specified chromatographic conditions were determined and their UV spectra recorded. To review the method, interlaboratory comparisons were performed with a spiked and a real ground water sample.     

Determination of polar nitroaromatic compounds in soils and the impact of the soil properties on the extraction results

An HPLC compatible method based on pressurized solvent extraction (PSE) for the determination of fifteen polar nitroaromatic compounds (pNC) in soil is described. The PSE method was compared with ultrasonic activated extraction. Thereby, analyzing sandy, clayey, and organic rich spiked soil samples, the influence of soil texture on the extraction yield was examined. Considering different soil properties recovery rates of investigated pNC and limiting extraction parameters were determined for both techniques. The extraction recovery of some pNC was found to show dependence on the clay content and correlation with the organic carbon amount of the soil.     

Particle beam LC/MS screening of polar compounds of contaminated ground water samples from a former gas plant

A commercial particle beam interface coupled to a single quadrupole mass spectrometer has been used for a nontarget screening of highly contaminated water samples from a former gas plant. A liquid chromatographic system has been used to separate hydrophilic compounds with a high percentage water gradient without any loss of efficiency in the MS interface. The ground water showed a high pollution burden in the total ion current chromatogram. Full scan EI mass spectra have been obtained for identification of unknown compounds which could be assigned to oxidation products of heterocyclic aromatic compounds, some known constituents of coal tar. The identification of 6(5H)-phenanthridinone has been confirmed by comparison with a corresponding standard. The difficulties of an unequivocal identification of isoquinolinone and methyl derivatives of quinolinone based on their EI mass spectra are discussed. Received: 7 March 1997 / Revised: 15 May 1997 / Accepted: 22 May 1997     

Particle beam LC/MS screening of polar compounds of contaminated ground water samples from a former gas plant

A commercial particle beam interface coupled to a single quadrupole mass spectrometer has been used for a nontarget screening of highly contaminated water samples from a former gas plant. A liquid chromatographic system has been used to separate hydrophilic compounds with a high percentage water gradient without any loss of efficiency in the MS interface. The ground water showed a high pollution burden in the total ion current chromatogram. Full scan EI mass spectra have been obtained for identification of unknown compounds which could be assigned to oxidation products of heterocyclic aromatic compounds, some known constituents of coal tar. The identification of 6(5H)-phenanthridinone has been confirmed by comparison with a corresponding standard. The difficulties of an unequivocal identification of isoquinolinone and methyl derivatives of quinolinone based on their EI mass spectra are discussed. Received: 7 March 1997 / Revised: 15 May 1997 / Accepted: 22 May 1997     

Switchable‐hydrophilicity solvent‐based microextraction combined with gas chromatography for the determination of nitroaromatic compounds in water samples

A simple, fast, sensitive, and low‐cost method was developed for the quantification of nitroaromatic compounds in water samples based on CO₂‐assisted liquid‐phase microextraction using a switchable‐hydrophilicity solvent followed by gas chromatography detection. Dipropylamine was used as extraction solvent with switchable hydrophilicity that can be miscible or immiscible upon the addition or removal of CO₂ as a reagent. Experimental parameters affecting the extraction efficiency such as the volume of acceptor phase, the volume of donor phase, pH of donor phase, ionic strength, and extraction time were investigated. Under the optimal conditions, detection limits and preconcentration factors were obtained in the ranges of 0.9–1.8 μg/L and 132–138, respectively. Also, the extraction recoveries of water samples were above 88%. Finally, the developed method was successfully applied to the determination of nitroaromatic compounds in real water samples.     

Identification of phenolic compounds in artichoke waste by high-performance liquid chromatography-tandem mass spectrometry

A new fast and efficient method combining liquid chromatography coupled to ionspray mass spectrometry in tandem mode with negative ion detection is described for the qualitative analysis of artichoke waste. Forty-five phenolic compounds were identified on the basis of their mass spectra in full scan mode, mass spectra in different MS-MS modes, and retention times compared with those of available reference substances. The major compounds were found to be both caffeoylquinic and dicaffeoylquinic acids, luteolin glucuronide, luteolin galactoside, quercetin, and some quercetin glycosides.     

Identification and quantification of flavonoids and ellagic acid derivatives in therapeutically important Drosera species by LC-DAD, LC-NMR, NMR, and LC-MS

Droserae herba is a drug commonly used for treatment of convulsive or whooping cough since the seventeenth century. Because of the contribution of flavonoids and ellagic acid derivatives to the therapeutic activity of Droserae herba, an LC?CDAD method has been developed for quantification of these analytes in four Drosera species used in medicine (Drosera anglica, D. intermedia, D. madagascariensis, and D. rotundifolia). During elaboration of the method 13 compounds, including three substances not previously described for Drosera species, were detected and unambiguously identified by means of extensive LC?CMS and LC?CNMR experiments and by off-line heteronuclear 2D NMR after targeted isolation. The most prominent component of D. rotundifolia and D. anglica, 2??-O-galloylhyperoside, with myricetin-3-O-??-glucopyranoside and kaempferol-3-O-(2??-O-galloyl)-??-galactopyranoside, were identified for the very first time in this genus. The LC?CDAD method for quantification was thoroughly validated, and enables, for the first time, separation and precise analysis of these analytes in Droserae herba. Simple sample preparation and use of a narrow-bore column guarantee low cost and simplicity of the suggested system, which is excellently suited to quality control of the drug or herbal medicinal products containing this drug.

Identification and Quantification of Polar Nitroaromatic Compounds in Explosive-Contaminated Waters by means of HPLC-ESI-MS-MS and HPLC-UV

In the area of former ammunition plants, contaminations caused by explosives and their degradation products are of great environmental relevance because of the immediate vicinity of ground- and drinking water reservoirs. Beside the determination of selected explosive-related compounds by means of HPLC with UV detection, a LC-MS-MS coupling utilizing electrospray ionisation was developed, which is particularly suited for the determination of highly polar compounds. Therewith, 12 different explosive-related compounds were identified and quantified on the basis of specific precursor-/ product-ion traces using the high selectivity and sensitivity of multiple reaction monitoring mode (MRM) of a triple quadrupole mass spectrometer. The LC-MS-MS-technique was applied to water samples from the area of a former ammunition plant. In addition to dinitrophenols and aminodinitrotoluenes which could be determined also by HPLC-UV, some highly polar compounds were found in the contaminated water, for example 3,5-dinitrobenzoic acid and 2-amino-4,6-dinitrobenzoic acid. The highest concentrations (14–40 μg L⁻¹) were found for two isomers of dinitrotoluenesulfonic acids. In order to assure the quantitative determination of polar substances in real samples with different composition, external calibration and standard addition method were compared. The presented LC-MS-MS-method is suited for screening and quantification of polar and hydrophilic explosive-related compounds from different classes of substances in a single analytical protocol.     

Analysis of volatile aromatic compounds in gasoline-contaminated ground water samples by static headspace sampling and high speed gas chromatography

A 15 second, high speed, gas chromatographic determination has been performed on the volatile aromatic compounds in gasoline-contaminated ground water following manual, static headspace sampling. Retention time reproducibility of the seven peaks studied ranged from 0.25 to 0.67 per cent (average relative standard deviation). Excellent linear correlations were obtained for plots of either peak height or peak area against the concentration of the compounds. Comparison was made between the results obtained from the analysis of three replicate samples of gasoline-contaminated ground water by the high speed GC, by two field-portable GCs, and by a laboratorybased GC. It is worthy of note that all the high speed GC analyses required for this study were accomplished in one day.     

Separation of 1,3‐dimethylamylamine and other polar compounds in a dietary supplement formulation using aqueous normal phase chromatography with MS

Five ingredients (caffeine, l ‐arginine, creatine, β‐alanine, and 1,3‐dimethylamylamine) from a workout supplement were separated by HPLC with UV detection and LC–MS using an analytical column based on silica hydride operating in aqueous normal phase mode. While RP methods were observed to be inadequate for the analysis due to low retention, aqueous normal phase chromatography was able to readily retain and resolve the analytes. After method development on the HPLC–UV system, the conditions were successfully transferred to an LC–MS system for analysis. Based on calibration curve data, estimates of 63.5, 380.3, and 13.1 mg/serving (5.50 g) were obtained for creatine, l ‐arginine, and 1,3‐dimethylamylamine, respectively. Standard addition data results were compared to those of the calibration curve study, and the two values differed by less than 1% in the case of creatine. The conditions are suitable for further development as a reliable means of quantitating the analytes in workout supplement formulations.     

Nitrogen speciation of polar petroleum compounds by compound class separation and on-line liquid chromatography – mass spectrometry (LC-MS)

Chromatography on Attapulgus clay and on silicic acid has been used to isolate ‘neutral’ and ‘basic’ nitrogen fractions from the 650–1050 °F distillate of an off-shore Californian crude oil. These polar compounds were subjected to on-line liquid chromatography – mass spectrometric (LC-MS) analysis using low voltage electron-impact ionization high resolution mass spectrometry (LVEI HRMS) and deuterated ammonia chemical ionization (ND₃ Cl) to determine the molecules' elemental composition and number of exchangeable hydrogen atoms. On-line separation of heavy oils into saturated, 1–4 ring aromatic, and polar compounds was performed by normal phase high performance liquid chromatography (HPLC) on a dinitroanilinopropyl (DNAP) silica column.     

水中挥发酚的在线蒸馏-固相萃取分离富集及测定

在顺序注射系统中实现了挥发酚的快速自动在线蒸馏,并用AmberliteXAD-7树脂微填充柱对其与4-氨基安替比林的衍生物在线固相萃取,被富集的衍生物可用少量乙醇有效地洗脱回收,以分光光度法检测.方法可用于较高浓度挥发酚(mg/L)样品的测定,也可根据需要适当增大进样体积,经富集后实现更低浓度水平(μg/L)挥发酚的测定.当富集过程中进样体积为4mL时,方法测定挥发酚的线性范围为0.004~0.3mg/L,检出限为0.002mg/L,相对标准偏差为1.4%(0.1mg/L,n=9).对多种实际水样中的挥发酚进行了测定,加标回收实验的回收率在96%~102%之间.     

Simultaneous preconcentration of polar and non‐polar organophosphorus pesticides from water samples by using a new sorbent based on mesoporous silica

A new mesoporous silica based on the sol–gel material cyanopropyltriethoxysilane (CNPrTEOS) was successfully synthesized by the hydrolysis and condensation of CNPrTEOS in the presence of ammonium solution as catalyst and methanol as solvent. It was used as a solid‐phase extraction sorbent for the simultaneous extraction of three organophosphorus pesticides, namely, polar dicrotophos and non‐polar diazinon and chlorpyrifos. Analysis was performed using high‐performance liquid chromatography with UV detection. CNPrTEOS was characterized by FTIR spectroscopy, field‐emission scanning electron microscopy and nitrogen gas adsorption. The surface area and average pore diameter of the optimum sol–gel CNPrTEOS are 379 m²/g and 4.7 nm (mesoporous), respectively. The proposed solid‐phase extraction based on CNPrTEOS exhibited good linearity in the range of 0.8–100 μg/L, satisfactory precision (1.15–3.82%), high enrichment factor (800) and low limit of detection (0.072–0.091 μg/L). The limits of detection obtained using the proposed solid‐phase extraction method are well below the maximum residue limit set by European Union and are also lower (13.6–48.5×) than that obtained by using a commercial CN‐SPE cartridge (0.98–4.41 μg/L). The new mesoporous sol–gel CNPrTEOS showed promising alternative as SPE sorbent material for the simultaneous extraction of polar and non‐polar organophosphorus pesticides.     

On‐site sampling and sample‐preparation approach with a portable sampler based on hollow‐fiber/graphene bars for the microextraction of nitrobenzene compounds in lake water

A novel on‐site sampling and sample‐preparation approach was developed and evaluated in the present work. In this procedure, hollow‐fiber/graphene bars (HF/GBs) were used for sampling and sample preparation. A handheld battery‐operated electric egg beater was utilized to support the HF/GBs and stir the sample solution to facilitate extraction at the sampling site. Four nitrobenzene compounds (nitrobenzene, o‐nitrophenol, m‐nitrophenol, and p‐nitrophenol) were used as model compounds. Several factors affecting performance, including types and amount of graphene used and extraction and desorption times, were investigated and optimized in the laboratory. Under optimized conditions, the enrichment factors of the four nitrobenzene compounds ranged from 46 to 69. Good linearities of 0.01–10 μg/mL with regression coefficients between 0.9917 and 0.9973 were obtained for all analytes. The LOD of the method was 0.3 ng/mL. Satisfactory recoveries (98–102%) and precision (1.0–5.8%) were also achieved. The ultrastructures and extraction mechanism of the HF/GBs were characterized and analyzed. The proposed approach coupled with high‐performance liquid chromatography was successfully applied in the extraction and determination of trace nitrobenzene compounds in lake water. Experimental results showed that the approach is simple, convenient, rapid, and practical for routine environmental monitoring.     

Tentative identification of polar and mid‐polar compounds in extracts from wine lees by liquid chromatography–tandem mass spectrometry in high‐resolution mode

Sustainable agriculture has a pending goal in the revalorization of agrofood residues. Wine lees are an abundant residue in the oenological industry. This residue, so far, has been used to obtain tartaric acid or pigments but not for being qualitatively characterized as a source of polar and mid‐polar compounds such as flavonoids, phenols and essential amino acids. Lees extracts from 11 Spanish wineries have been analyzed by liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) in high resolution mode. The high‐resolution power of LC–MS/MS has led to the tentative identification of the most representative compounds present in wine lees, comprising primary amino acids, anthocyans, flavanols, flavonols, flavones and non‐flavonoid phenolic compounds, among others. Attending to the profile and content of polar and mid‐polar compounds in wine lees, this study underlines the potential of wine lees as an exploitable source to isolate interesting compounds. Copyright © 2015 John Wiley & Sons, Ltd.     

Narcissistic aggregation of steroid compounds in diluted solution elucidated by CSI-MS, PFG NMR and X-ray analysis

Large-scale aggregated chain structures of progesterone, estrone, cortisone, hydrocortisone and cholic acid were observed in diluted solution by means of cold-spray ionization mass spectrometry (CSI-MS) and pulsed field gradient (PFG) NMR. The crystal structures were determined by X-ray crystallography, and the relationship between the crystal and solution structures is discussed. It is suggested that the intermolecular hydrogen bondings observed in the crystal might be partly retained in diluted solution.