Monolithic spin column: a new extraction device for analysis of drugs in urine and serum by GC/MS and HPLC/MS

A monolithic spin column was developed for the extraction of analytes from biological materials. This column was constructed by packing a monolithic silica disk into a spin column. Sample loading, washing, and elution of the target drugs were accomplished simply by centrifugation of the column. Opiates and benzodiazepines are abused throughout the world. Identification and quantification of these drugs is very important to solve crimes or the cause of death. Three opiates (morphine, codeine, and dihydrocodeine) were extracted from urine and serum by using the column. After conversion to trimethylsilyl derivatives of the opiates by vigorous mixing with the derivatizing reagent, the solution was subjected to GC/MS. A linear curve was observed for opiates from 10 to 2500 ng/mL in urine and 5 to 1200 ng/mL in serum, respectively (correlation coefficient > 0.996). For benzodiazepines, the hydroxyl metabolites of triazolam and etizolam were extracted from urine using the column, and the eluate was directly analyzed by HPLC/MS without evaporation. The LOD values were at the ppb level, with RSD values lower than 15%. The proposed methods were successfully applied to clinical and forensic cases, and good agreement of results was obtained compared to conventional methods.     

分散固相萃取结合高效液相色谱-串联质谱法测定羊肝中19种全氟烷基酸

建立了羊肝样品中19种全氟烷基酸(PFAs)的高效液相色谱-串联质谱检测方法。样品经酸化乙腈提取,加入乙二胺-N-丙基硅烷(PSA)、C18、石墨化炭黑(GCB)3种吸附剂后涡旋振荡对样品进行净化。以高效液相色谱-串联质谱(HPLC-MS/MS)检测萃取液中PFAs含量,采用C18色谱柱分离,负离子模式电喷雾电离,配合多级反应离子扫描(MRM)定性分析目标化合物。考察了盐酸和吸附剂的用量对加标回收率的影响,优化了主要影响因素和实验条件。在优化条件下采用同位素标记内标物进行定量分析。19种PFAs在0.05~20 μg/kg范围内线性关系良好,相关系数R>0.998,检出限(LOD)为0.004~0.111 μg/kg,定量限(LOQ)为0.012~0.370 μg/kg。在0.5、1.0、2.0 μg/kg加标水平下,19种PFAs的加标回收率为80%~128%,相对标准偏差(RSD)范围为0.31%~11.1%。该方法快速、简单、准确,适用于羊肝样品中19种PFAs的检测分析。     

Comprehensive two-dimensional gas chromatography in the analysis of dietary fatty acids

Comprehensive two-dimensional gas chromatography utilising a semi-rotating cryogenic modulator was applied to the analysis of dietary milk derived fatty acids. Four column combinations were tested: two polar-nonpolar and two different nonpolarpolar column combinations. Best results were obtained with a nonpolar-polar column set, with narrow-bore (50 microm ID) Carbowax column as the second column. The GC x GC method clearly improved the separation efficiency of the fatty acids in comparison with one-dimensional GC analysis and proved to be suitable for the quantification of the analytes. The relative standard deviations (RSD) of the retention times in the first and second dimensions were on average 0.06% and 4.9%, respectively. The relative RSD for peak volumes was on average 2.9%.     

Method development for analysis of short- and long-chain perfluorinated acids in solid matrices

In order to help to elucidate the transport and fate of perfluorinated acids (PFAs) in the environment, a reliable and sensitive analytical method has been developed in present study for determination of short- and long-chain PFAs in various solid matrices. The method consisted of solvent extraction of PFAs from solid matrices using sonication, solid phase extraction (SPE) using weak anion exchange (WAX) cartridges, clean-up of SPE eluent with dispersive carbon sorbent and quantitation by high performance liquid chromatography-negative electrospray-tandem mass spectrometry (HPLC-negative ESI-MS/MS). The method detection limits (MDL) and quantitation limits (MQL), which were analyte- and sample-dependent, ranged from 0.02 to 0.06?ng?g^?1 and 0.10 to 0.90?ng?g^?1, respectively. The recoveries of all PFAs were generally good enough for quantitative analysis of these chemicals (57–115%), especially for short-chain (<C8, 80–115%) PFAs excluded in previous studies because methods were not available. The precisions of this method, represented by the percent relative standard deviation (RSD) of spiked measurements, were in a range of 1–19%. In addition, matrix effect did not affect analyte quantification in solid matrices in most cases, and the validated method was successfully applied to analyses of short- and long-chain PFAs in various solid matrices.     

Determination of cyanuric acid using exact matching isotope dilution mass spectrometry

A high‐accuracy double isotope dilution mass spectrometric method using an exact matching approach with GC coupled to a mass spectrometer for the analysis of cyanuric acid in fortified milk powder was developed. Various parameters for sample clean‐up such as the type of SPE cartridge, GC column and type of derivatizing agent used were investigated. The method was found to be linear in the concentration range of 0.03 to 2 mg/kg of cyanuric acid in milk powder. LOD and LOQ were found to be 0.9 and 3 μg/kg, respectively. Recoveries in the range of 95.7 to 102.2% were obtained for the in‐house fortified milk powder samples, with RSD of measurements in the range of 0.2 to 3.0%. A metrological approach was undertaken to examine all possible biases that contributed to the combined measurement uncertainty of the method. This high‐accuracy method can serve as a reference method for techniques commonly applied in routine testing laboratories.     

Validation of a gas chromatographic method for determination of fatty alcohols in 10 mg film-coated tablets of policosanol

A gas chromatographic method using a packed column and 1-eicosanol as an internal standard was validated for the determination of the fatty alcohols that compose policosanol in 10 mg film-coated tablets. The alcohols were determined as trimethylsilyl derivatives, prepared with N-methyl-N-trimethylsilyltrifluoroacetamide. The method can detect degradation products with high retention times, without interfering with the peaks of the active principle. Good linearity (correlation coefficient = 0.9992) and accuracy (mean recovery -100.27 +/- 1.66%) were proven over a range of 25-200% of the nominal concentration. Within- and between-day precision at the nominal 100% value met the acceptance criteria (<2%). Ruggedness was examined through an intralaboratory experimental study in which 6 operational changes were made; the changes were found to have no effect on quantitation, repeatability, resolution, and relative retention time. The method is suitable for the quality control process and stability studies of these tablets.     

Validation of a gas chromatographic method for determining fatty alcohols that compose policosanol in five-milligram film-coated tablets.

A gas chromatographic method using a packed column and 1-eicosanol as an internal standard was developed and validated for determination of the aliphatic fatty alcohols that compose policosanol in 5 mg film-coated tablets. The alcohols were analyzed as trimethylsilyl (TMS) derivatives, prepared with N-methyl-N-trimethylsilylfluoroacetamide. The method can detect degradation products with high retention times without interfering with the peaks of the active principle. Good linearity (correlation coefficient = 0.9996) and accuracy (recovery = 100.44%) were proven over a range of 50-150% of the nominal concentration. Within-day and between-day precisions at the nominal 100% value met the acceptance criteria (< 2%). Ruggedness was examined through an intralaboratory experimental study in which 7 operational changes were made and the observed results were quantitation, repeatability, resolution, and relative retention time. Among these results, only the relative retention time (tC28,C20) was significantly affected when the column used was 2.1 m instead of 3.1 m. Repeatability and reproducibility (r = 0.1506 and R = 0.2450, respectively) were obtained from a uniform-level interlaboratory test. The method is suitable for quality control and stability studies of these tablets.     

气相色谱法测定直接电氧化反应液中2-甲基萘和2-甲基-1,4-萘醌

建立了气相色谱同时测定反应液中的2-甲基萘和2-甲基-1,4-萘醌的方法.该法以萘为内标物,在DB-1色谱柱上进行分离,氢火焰离子化检测器.方法的回收率98%～102%,相对标准偏差小于2%.     

衍生化气相色谱法测定早强剂中三乙醇胺含量

建立了衍生化气相色谱法定量分析水泥早强剂中三乙醇胺含量的方法。以丙三醇作为内标,采用HP-5毛细管柱分离样品,氢火焰离子化检测器(FID)测定三乙醇胺含量。三乙醇胺在0.2～5.0mg/mL范围内与三乙醇胺/内标的乙酰化物色谱峰面积的比值呈线性关系,相关系数r=0.9996。方法检出限为42.6μg/mL,平均回收率为96.6%,相对标准偏差(RSD)为0.759%。该方法具有操作简便、快速、准确等优点,可用于测定水泥早强剂中三乙醇胺的含量。     

Analytical study of comprehensive and targeted multidimensional gas chromatography incorporating modulated cryogenic trapping

This paper reports the results of an analytical study comparing capillary gas chromatography (GC) operated in the normal mode with 2 new GC techniques, comprehensive GC (GC x GC) and targeted (or selective) multidimensional GC, which use a longitudinally modulated cryogenic system (LMCS), recently developed in our laboratory. A high-temperature application of derivatized sterols, of interest in fecal pollution monitoring, was chosen for this work. A directly connected coupled-column ensemble was used, comprising a nonpolar column and a moderately polar column. With LMCS, effluent from the first column is zone-compressed in a cryogenic trap and then pulsed to a short second column, producing narrower peaks with sharp, tall peak responses at the detector. The modulator is operated at a constant frequency, e.g., 0.25 s(-1), to produce the GC x GC result, or is moved in a predefined manner so that whole peaks are selectively trapped and subsequently pulsed through to the second column in the targeted mode. Standard solutions containing a mixture of 7 sterols and 5-alpha-cholestane internal standard were used. Detection sensitivity is increased by a factor of >25 with the use of LMCS. The estimated limit of detection was about 0.1 microg/mL when normal GC with flame ionization detection (GC/FID) and a 1.0 microL splitless injection volume were used, compared with 0.02 and 0.004 microg/mL for the LMCS operated in GC x GC and selective modes, respectively. Calibration curves for GC/FID were linear over the 0.1-2.0 microg/mL range tested. Reproducibilities for the GC x GC and normal GC modes were comparable; generally, relative standard deviations (RSD) were on the order of 3-4%, based on raw peak responses. Improved reproducibility was found for selective LMCS operation, at an RSD of around 2%; with internal standardization, better results were achieved. The coupled-column arrangement allowed complete separation of sterol peaks from overlapping impurity peaks in a number of instances with LMCS modes, and its use should improve data quality over that of normal GC operation, in which the overlapping peaks interfere with measurement of peak response in the normal mode.     

Gas chromatography of amino acids: Use of a fused-silica capillary column in the determination of plasma amino acids

A capillary chromatographic procedure using a fused silica column is described which can be used to quantitatively determine amino acids in plasma following the pre-chromatographic “clean-up” described in a recent paper [1]. In substituting this procedure for that involving a packed column, advantage has been taken of the greater resolving power to separate amino acids from background component peaks. In order to extend this advantage and provide a sound basis for quantitative analysis, the technique of cold on-column injection was employed. As a result, good precision of standard analysis was obtained with relative standard deviation (RSD) values for all amino acids of less than 4%. Application of the entire procedure to plasma samples yields RSD values of better than 10% for all amino acids with recoveries ranging from 72% to 104%. Simultaneous determination of plasma amino acid levels by gas chromatography (GC) using capillary columns and by classical ion exchange (CIE) showed reasonable agreement. Statistical evaluation showed no significant difference between twelve amino acids. Values for the remaining two, namely, phenylalanine and histidine are significantly different (p < 0.005). Comparison of the values obtained from GC capillary and packed columns reveals no significant difference between fourteen amino acids. Significant differences exist between results for phenylalanine and tyrosine (p < 0.001). It is concluded that there is good agreement between data obtained by GC capillary and CIE techniques and that differences between results for phenylalanine and histidine are method related.     

Organotin analysis by gas chromatography–pulsed flame-photometric detection (GC–PFPD)

Monobutyltin (MBuT), dibutyltin (DBuT), and tributyltin (TBuT) mixtures have been separated and quantified by gas chromatography with pulsed flame-photometric detection (GC–PFPD). The compounds were first derivatized with NaBEt₄, then extracted with hexane and injected into the GC in splitless mode. Optimum GC and detector conditions were established. For GC, various injector temperatures and oven temperature programs were tested. For the PFPD detector, gate settings (gate delay and gate width) and detector temperature were optimized. A very good linearity was obtained up to 100–150 ppb for all organotin compounds. The detection limits obtained were: MBuT (0.7 ppb), DBuT (0.8 ppb), and TBuT (0.6 ppb). RSD for repeatability and reproducibility were well below 20% when the instrument was in routine operation. A biological sample (CRM 477) was also analyzed for organotins. Extraction from the biological matrix was performed with TMAH. Besides the increased risk of contamination, the derivatization step seemed to be critical. pH and amount of derivatizing agent were tested. When using an internal standard (TPrT) between 90% and 110% of the certified amounts of organotin were recovered.     

气相色谱法测定洗涤剂用脂肪醇

建立了一种快速、准确测定洗涤剂用脂肪醇的气相色谱分析方法。采用气相色谱和质谱联机方法对洗涤剂用脂肪醇进行了定性分析,采用气相色谱法对洗涤剂用脂肪醇进行了定量分析。用正构脂肪醇对定量分析方法进行了考察,其结果的相对标准误差为2．2％。用气相色谱确定了每个组分的含量,定量结果的相对标准偏差小于2．6％。分析结果为装置操作优化及改进洗涤剂脂肪醇的正构度提供了技术支持。     

Comparison Between Methyl and Trimethylsilyl Ester Derivatives in the Separation and GC Quantification of Triterpene Acids in Eugenia brasiliensis Leaf Extract

This study details a method to characterize the triterpene acid-rich extract obtained from the defatted leaves of Eugenia brasiliensis (Myrtaceae) via extraction with 2 % NaOH in ethanol at room temperature. The crude extract (yield 2.35 %) was submitted to analysis by gas chromatography coupled to mass spectrometry (GC–MS) confirming ursolic acid as its major compound. The optimal conditions for the separation of oleanolic, betulinic and ursolic acids were assayed by GC with flame ionization detection (GC–FID) using two different columns (DB-5 and DB-17HT) and by applying two distinct derivatizing protocols. The use of a DB-17HT column led to the best results, with a shorter runtime and a better resolution (Rs) between the oleanolic and betulinic signals for both the bis-trimethylsilyl (Rs 2.84) and methyl ester derivatives (Rs 2.47). A DB-5 column also gave satisfactory results for the TMS ester, with a runtime of 30 min and Rs 2.14. Ursolic acid in the crude extract was quantified by comparison to two individual standard curves determined using commercial ursolic as its TMS derivative on the DB-5 column and its methyl ester on the DB-17HT column. Good linearity was achieved in both cases (r ² = 0.9776 and 0.9953, respectively), and the amounts of ursolic acid in the extracts were calculated to be 144.7 and 147.9 mg·g^?1, respectively. These results showed no significant differences when compared using Tukey’s HSD test. Total triterpene acids amounted to 0.52 % in E. brasiliensis dry leaves.     

Fused silica capillary column GC/MS for the analysis of priority pollutants

Operational characteristics have been determined for fused silica capillary column (FSCC) GC/MS as applied to “extractable” priority polutants. Chromatographic data show excellent relative retention time (RRT) intralaboratory precision and interlaboratory accuracy when multiple internal standards are empolyed. Potential chromatographic problems, such as column overload and “double peaking”, are addressed. Response factor relative standard deviations (RSD) at 50 ng for most of the extractable priority pollutants over the long term indicated precise determination (i.e. RSD generally ≤ 10%). Linearity was demonstrated over two orders of magnitude for FSCC GC/MS analysis of compounds with relatively low and high RF (response factor) values. Potential quantitative problems, such as saturation, are discussed. For certain aromatic priority pollutants interlaboratory RF agreement was observed. This was noted as perhaps the most important property of FSCC GC/MS analysis when the multiple internal standard approach is utilized. Determinations of extractable priority pollutants are directly compared for paced column GC/MS and FSCC GC/MS analysis of separate and composited extracts. For six extracts analyzed in triplicate, the latter configuration was shown to produce more consistent results. In view of the superior analysis logistics of composite extract FSCC GC/MS analysis, this approach was established as the preferred method for the analysis of priority pollutants classified as extractable.     

全二维气相色谱-电子捕获检测器法分析土壤中毒杀芬同类物的残留

建立了全二维气相色谱-电子捕获检测器(GC× GC-μECD)检测土壤中毒杀芬同类物的分析方法.以非极性的DB- XLB(20 m×0.25 mm×0.25 μm)为第一色谱柱,中等极性的BPX-50(2 m×0.1 mm×0.1 μm)为第二色谱柱,对土壤中23种高关注毒杀芬同类物进行了分离鉴定,并采用基质曲线外标法进行定量分析.本方法在1～200,μg/L浓度范围内,毒杀芬同类物的线性相关系数(r2)均大于0.99,方法检出限(S/N=3)为0.039～0.482 μg/L,基质加标毒杀芬同类物的回收率为55％～115％,相对标准偏差(RSD)均小于30％(n=5).利用本方法对毒杀芬污染的土壤样品进行了测定,获得了较好的分离效果.     

气相色谱法测定污水处理产生的氧 亚氮的分析方法研究

建立了气相色谱法(GC/ECD)检测污水处理过程中产生的温室气体氧化亚氮(N2O)的分析方法.确定了最佳实验条件:进样口温度、柱温和ECD检测器温度分别为105、100、300℃,以95％ Ar +5％ CH4为载气,柱流速和尾吹气流速分别为25、50 mL/min.N2O的质量浓度在0.255～ 100 mg/L范围...     

Improved procedure for the the determination of rofecoxib in human plasma involving 96-well solid-phase extraction and fluorescence detection

An improved assay for the determination of rofecoxib in human plasma samples is described. The analyte and an internal standard were extracted from the plasma matrix using solid-phase extraction in the 96-well format with an Empore C8-SD extraction plate. The analytes are chromatographed on a Waters Symmetry C18 analytical column (3.5 microm, 50x4.6 mm) with a mobile phase consisting of acetonitrile-water (35:65, v/v). Analyte detection was via fluorescence following post-column photochemical derivatization. Eight point calibration curves over the concentration range of 0.5-80 ng/ml yielded a linear response when a 1/y weighted linear regression model was employed. Based on the replicate analyses (n=5) of spiked standards, the within-day assay precision was better than 8% RSD at all points on the calibration curve, within-day accuracy was within 6% of nominal at all standard concentrations. The between-run precision and accuracy of the assay, as calculated from the results of the analysis of quality control samples, was better than 7% RSD and within 5% of nominal. Assay throughput was improved by a factor of three as compared to previously described methods. The method was partially automated using a combination of a Packard Multi-Probe liquid handling system and a TomTec Quadra 96 workstation.     

三唑酮的气相色谱分析

研究了三唑酮的气相色谱分析条件 ,选择以 10 %SE 30为固定液 ,ChromosorbW (AW DMCS)载体填充的色谱柱 ,选择邻苯二甲酸二乙酯为内标 ,采用内标标准曲线法作为定量分析的方法 ,相对标准偏差 <0 .94 % ,线性相关系数为 0 .9990 4 ,加标回收率在 10 0 .1%～ 10 1.9%之间。方法简便 ,快捷 ,重复性好。     

Short metal capillary columns packed with polymer-coated fibrous materials in high-temperature gas chromatography

The high-temperature gas chromatographic (GC) separation of several semivolatile compounds is studied with a short metal capillary column packed with fibrous material, having a polydimethylsiloxane coating thereon. Taking advantage of the excellent heat-resistance of the fiber and also the combination of the surface-deactivated metal capillary, a temperature-programmed separation up to 450 degrees C is successfully demonstrated for the separation of polymer standard samples. The average molecular weight of the commercially-available polymer standard samples for size exclusion chromatography (SEC) is estimated by high-temperature GC analysis and compared with the nominal value determined by a conventional SEC method. Although a slight deviation for the number-average molecular weight is observed between the GC and SEC analysis, the data for the weight-average molecular weight shows a good agreement in these methods. The results also suggest the future possibility of the fiber-packed metal capillary as a miniaturized GC column with an increased sample loading capacity.