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PubMedDate not supplied

Statistical approach for risk assessment of aflatoxin sampling plan used by manufacturers for raw shelled peanuts.

Processed food manufacturers often use acceptance sampling plans to screen out lots with unacceptable levels of contamination from incoming raw material streams. Sampling plan designs are determined by specifying sample sizes, sample preparation methods, analytical test methods, and accept/reject criteria. Sampling plan performance can be indicated by plotting acceptance probability versus contamination level as an operating characteristic (OC) curve. In practice, actual plan performance depends on the level of contamination in the incoming lot stream. This level can vary considerably over time, among different crop varieties, and among locales. To better gauge plan performance, a method of coupling an OC curve and crop distributions is proposed. The method provides a precise probabilistic statement about risk and can be easily performed with commercial spreadsheet software.

Aflatoxins↗
PubMed2001

Analytical chromatography for recovery of small amounts of staphylococcal enterotoxins from food.

Sample preparation is an important element in the detection of toxins in food samples. In this work, a simple analytical sample preparation method for recovery of small amount of staphylococcal enterotoxin B (SEB) and staphylococcal enterotoxin A (SEA) in food samples was developed. Cation exchanger carboxymethylcellulose (CM) was used for small-scale batch chromatography isolation of SEB from infant formula and from mushrooms spiked with SEB. The resulting materials were analyzed for SEB by Western immunoblotting. Nearly all of the extraneous substances in the sample were removed by this procedure with no significant loss of the toxin. Using this method, even small amounts of SE (0.75 ng/g) can be recovered and immunologically analyzed by Western blotting or by ELISA with a very low background. Because this method is effective, rapid, simple and inexpensive, it has the potential to be a general method for the preparation of samples used for analysis of SEs.

Agaricales↗
PubMed1989

Simplified procedures for the determination of fenoldopam and its metabolites in human plasma by high-performance liquid chromatography with electrochemical detection: comparison of manual and robotic sample preparation methods.

Quantitative analytical methods, based on high-performance liquid chromatography with electrochemical detection, were developed for fenoldopam and its metabolites in human plasma. Two extraction methods, a liquid-liquid extraction method for fenoldopam and its methoxy metabolites and a liquid-solid extraction procedure for the sulfate and glucuronide conjugates of fenoldopam were developed. The extractions can either be performed manually or by robot. The limit of detection for fenoldopam, its sulfate and methoxy metabolites was 0.025, 2 and 0.5 ng/ml, respectively, at a signal to noise ratio of 4. The intra-assay and inter-assay coefficients of variation for both manual and robotic extraction procedures were comparable. These methods were suitably selective and sensitive for pharmacokinetic and metabolic studies of fenoldopam.

Adult↗
PubMed2006

Ultrasound in analytical chemistry.

Ultrasound is a type of energy which can help analytical chemists in almost all their laboratory tasks, from cleaning to detection. A generic view of the different steps which can be assisted by ultrasound is given here. These steps include preliminary operations usually not considered in most analytical methods (e.g. cleaning, degassing, and atomization), sample preparation being the main area of application. In sample preparation ultrasound is used to assist solid-sample treatment (e.g. digestion, leaching, slurry formation) and liquid-sample preparation (e.g. liquid-liquid extraction, emulsification, homogenization) or to promote heterogeneous sample treatment (e.g. filtration, aggregation, dissolution of solids, crystallization, precipitation, defoaming, degassing). Detection techniques based on use of ultrasonic radiation, the principles on which they are based, responses, and the quantities measured are also discussed.

Analytic Sample Preparation Methods↗
PubMed2003

Quantitative determination of benazepril and benazeprilat in human plasma by gas chromatography-mass spectrometry using automated 96-well disk plate solid-phase extraction for sample preparation.

An analytical method for the determination of benazepril and its active metabolite, benazeprilat, in human plasma by capillary gas chromatography-mass-selective detection, with their respective labelled internal standard, was developed and validated according to international regulatory requirements. After addition of the internal standards, the compounds were extracted from plasma by solid-phase extraction using automated 96-well plate technology. After elution, the compounds were converted into their methyl ester derivatives by means of a safe and stable diazomethane derivative. The methyl ester derivatives were determined by gas chromatography using a mass-selective detector at m/z 365 for benazepril and benazeprilat and m/z 370 for the internal standards. Intra- and inter-day accuracy and precision were found to be suitable over the range of concentrations between 2.50 and 1000 ng/mL.

Benzazepines↗
PubMed2006

Quantification of estrogenic mycotoxins at the ng/L level in aqueous environmental samples using deuterated internal standards.

Because of their pronounced estrogenicity, resorcyclic acid lactones (RALs) are of concern in aqueous environments even at the low ng/L level. Therefore, we developed an accurate, precise and sensitive HPLC-MS/MS method to detect these mycotoxins in different aqueous environmental samples. The compounds investigated included zearalenone (ZON), alpha- and beta-zearalenol, zearalanone as well as alpha- and beta-zearalanol. The use of isotope labelled internal standards (in this case deuterated RAL-analogues) ensured an accurate quantification of the target analytes, independent of matrix compounds interfering with the analytes during ionisation and analyte losses occurring during sample preparation. Sample enrichment was carried out by solid-phase extraction (SPE) using Supelclean Envi-18 cartridges. Absolute method recoveries for all analytes ranged from 95 to 108%, 70 to 102%, and 76 to 109%, method detection limits from 0.5 to 2.1 ng/L, 0.4 to 1.1 ng/L, and 0.8 to 12.4 ng/L and precision from 3 to 14%, 2 to 13% and 4 to 16% in drainage water, river water and wastewater treatment plant (WWTP) effluent, respectively. The method was applied to verify the emission of RALs from a Fusarium graminearum infested crop field into the drainage system. Zearalenone was present in drainage water in concentrations up to 30 ng/L. So far, none of the other five investigated compounds have been detected.

Analytic Sample Preparation Methods↗
PubMed2006

Current perspectives in analyte extraction strategies for tin and arsenic speciation.

Nowadays, reliable and robust detectors can be considered standard laboratory instrumentation, which, for most of the elements provide quantitation limits in the lower ng/g range. Despite these advances in detector technology, sample preparation is by far the most important error source in modern analytical method development and can be judged as the "Achilles' heel" of any analytical process regarding reliability of the obtained results and time consumption. The aim of the present review is to highlight modern trends for tin and arsenic speciation, as these analytes can be considered as models for challenges in modern method development in this field. First background information, legislative aspects and current needs are elucidated. Then the role of sample treatment within the process of method development in speciation is discussed, followed by a presentation of modern extraction techniques, matching the requirements for arsenic and tin speciation analysis: to provide mild conditions in order to ensure species preservation, to improve species recovery, to enhance sample throughput and to be suitable for hyphenation with chromatographic separation systems. The review includes applications on tin and arsenic speciation, covering the period of 2001-2006.

Analytic Sample Preparation Methods↗
PubMed2005

Digital microfluidics with in-line sample purification for proteomics analyses with MALDI-MS.

An in-line sample purification method for MALDI-MS, which relies on the electrowetting-on-dielectric (EWOD)-based technique for digital microfluidics, is reported. In this method, a droplet containing peptides and impurities is moved by EWOD and deposited onto a Teflon-AF surface. A droplet of water is subsequently moved over the spot, where it dissolves and removes the impurities. A droplet containing MALDI matrix is then moved to the spot, which is analyzed by MALDI-MS. This purification method reduces the number of salt adduct peaks caused by low concentrations of impurities (e.g., 20 mM sodium phosphate), and reduces or eliminates the catastrophic effects of high concentrations of impurities (e.g., 8 M urea). The method was used to purify spots made by depositing multiple droplets of contaminated peptides. Spectra from the purified spots showed an increase in the S/N ratio as a function of the number of droplets deposited; when not purified, the S/N ratio remained constant regardless of the number of droplets. Finally, the method was used to purify protein digests for peptide mass fragment (PMF) searches, and was shown to be more efficient than the conventional method of purification with reversed-phase-packed pipet tips. We anticipate this new, in-line sample purification technique for EWOD-MALDI-MS will enable development of integrated high-throughput proteomics analysis methodologies.

Analytic Sample Preparation Methods↗
PubMed2004

Increasing the efficiency of pharmacokinetic sample procurement, preparation and analysis by liquid chromatography/tandem mass spectrometry.

The movement towards a 96-well format has greatly increased productivity and throughput in bioanalytical laboratories. Improvements in automated sample preparation and analytical methods have further contributed to increased productivity. We have focused on sample collection and transfer to the bioanalyst and have found improvements to the current available methods. The problem of manual transfers and plasma clotting issues can be overcome with the use of microtainers. Specifically, for illustrative purposes, three proprietary Theravance compounds were tested for stability, non-specific binding, and electrospray ion suppression in microtainers. There were no issues with stability, non-specific binding or ion suppression for the above compounds even after leaving plasma samples in the microtainers over long periods of time. The microtainers are robot-compatible and the resulting plasma can be transferred without clotting issues. To date, all in-house compounds successfully analyzed and tested using the microtainers have mass ranges between 200 and 1800 Da, pK(a) ranges between 3.8 and 10.3, and logD ranges between -1.7 and 4.2. Once samples are transferred into 96-well plates, flexibility in preparation and analysis is available. Together with automated sample preparation and the use of liquid chromatography/tandem mass spectrometry (LC/MS/MS) as an analytical tool, the use of microtainers as sample collection tubes and for sample storage saved considerable time, cost and effort in both of our pharmacokinetic (PK) and bioanalytical groups. This in turn has led to an increased efficiency and overall throughput in support of our drug discovery effort.

Animals↗
PubMed2006

Sample treatments prior to capillary electrophoresis-mass spectrometry.

Sample preparation is a crucial part of chemical analysis and in most cases can become the bottleneck of the whole analytical process. Its adequacy is a key factor in determining the success of the analysis and, therefore, careful selection and optimization of the parameters controlling sample treatment should be carried out. This work revises the different strategies that have been developed for sample preparation prior to capillary electrophoresis-mass spectrometry (CE-MS). Namely the present work presents an exhaustive and critical revision of the different samples treatments used together with on-line CE-MS including works published from January 2000 to July 2006.

Analytic Sample Preparation Methods↗
PubMed1995

Quality auditing of chromatographic data.

We have developed a method for consistent, in-depth audit of the integrity of chromatographic records. The approach includes definition of the analyte, the method of analyte sample preparation and analysis, and the analyte concentration range. Acceptance criteria (if any) defined in the protocol or method are compared to the data. Run parameters are compared to those specified in the methodology. Certification of the standard is verified and the limit of quantitation for each run is identified and compared to data. Reasons for data discard and/or reassay are examined. If calculation software is not validated, representative calculations are recomputed and chromatograms are examined for attributability. These parameters are examined in addition to other Good Laboratory practice considerations such as sample identity, sample integrity, and transcription accuracy.

Chromatography↗
PubMed2006

Chromatographic quantitation at losses of analyte during sample preparation. Application of the modified method of double internal standard.

Known methods of quantitative chromatographic analysis (calibration, external standard, internal standard and standard addition) require the application of sample preparation techniques without significant losses of analytes. If this condition cannot be satisfied, the compensation of these losses should be provided. The modification of known method of quantitative chromatographic analysis (double internal standard), implying the addition of two homologues (previous and following) of target analytes as internal standards into initial samples is considered. This approach permits us to compensate significant losses both analytes and standards at all stages of sample preparation. The advantages of this method are demonstrated on the examples of liquid-liquid extraction, head space analysis (HSA), distillation of volatile compounds with volatile solvents (concentration in condensates) and evaporation of volatile solvents (concentrating in the residues of solvents). In all cases the application of two homologues as internal standards provides accurate results (the typical relative errors are within 1-6%) at the values of a factor of composition distortion of initial samples (K', the definition is suggested) from 0.2 up to 4. These results are in accordance with general relationships between variations in any physicochemical properties of organic compounds within homologous series. The single found exception was the evaporation of volatile solvents (the open phase transition process) when to get the results with relative errors not more then +10% requires the minimal changes in the composition of initial samples (K' values should not be more then approximately 1.5).

Calibration↗
PubMed2006

Superheated liquid extraction of oleuropein and related biophenols from olive leaves.

Oleuropein and other healthy olive biophenols (OBPs) such as verbacoside, apigenin-7-glucoside and luteolin-7-glucoside have been extracted from olive leaves by using superheated liquids and a static-dynamic approach. Multivariate methodology has been used to carry out a detailed optimisation of the extraction. Under the optimal working conditions, complete removal without degradation of the target analytes was achieved in 13 min. The extract was injected into a chromatograph-photodiode array detector assembly for individual separation-quantification. The proposed approach - which provides more concentrated extracts than previous alternatives - is very useful to study matrix-extractant analytes partition. In addition, the efficacy of superheated liquids to extract OBPs, the simplicity of the experimental setup, its easy automation and low acquisition and maintenance costs make the industrial implementation of the proposed method advisable.

Analytic Sample Preparation Methods↗
PubMed2006

Comparison of sampling and analytical methods used during the preparation of methyl methacrylate bone cements.

Surgeons, surgical nurses, and other operating room staff are exposed to airborne concentrations of methyl methacrylate during the preparation of orthopedic bone cement. Three sampling and analysis methods have been used to measurement methyl methacrylate in this work environment: (1) direct-reading photoacoustic infrared spectrometry, (2) solid sorbent and gas chromatography with flame ionization detection, and (3) colorimetric detector tubes. Previous studies have measured operating room exposures and judged the efficacy of cement mixing wth little, if any, regard for method sensitivity, detection limits, precision, or accuracy. The present investigation was designed to allow concurrent monitoring of methyl methacrylate levels from the same air volume using each of the three methods. Three popular orthopedic bone cement products were mixed during a number of repeat preparations (n = 36). Airborne concentrations were monitored concurrently during each preparation. Attention was given to the proper treatment of detection limits, and the results are reported both as raw data and descriptive statistics. A one-way ANOVA using a Tukey-Kramer HSD comparison was performed on method-specific results indicating that the photoacoustic infrared spectrometry and solid sorbent, gas chromatography with flame ionization detection are in good agreement, but the colorimetric detector tube method reports significantly different airborne concentrations. It is concluded that previous assessments using the photoacoustic infrared spectrometry and solid sorbent, gas chromatography with flame ionization detection may be relied on, but the detector tube method underreports actual exposures. Accordingly, the results of past exposure assessments and mixing method efficacy studies using colorimetric detector tubes may not be reliable.

Air Pollutants, Occupational↗
PubMed2006

Miniaturised selective pressurised liquid extraction of polychlorinated biphenyls from foodstuffs.

The feasibility of miniaturised pressurised liquid extraction (PLE) with in-cell purification and subsequent gas chromatography with micro-electron capture detection (GC-micro-ECD) for the determination of prioritary and toxic polychlorinated biphenyls (PCBs) in a variety of foodstuffs (fat contents in the range 22-49%, w/w, on a freeze-dried basis) has been investigated. After optimisation of the several experimental parameters affecting the efficiency of the selective PLE process, the developed method provided quantitative recoveries of the endogenous PCBs studied and complete fat elimination in a single step using n-hexane as extraction solvent. A total solvent volume of 3.5 mL was used for the two consecutive 7 min static PLEs of 100-mg samples. Detection limits using GC-micro-ECD were below 0.2 ng/g freeze dried sample for all 22 PCBs investigated in real-life foodstuffs, and the repeatability of the complete PLE plus GC-micro-ECD method as calculated for the analysis of the endogenous PCBs in general was better than 14%. Comparison of the miniaturised PLE method developed with either conventional Soxhlet extraction or matrix solid phase dispersion with subsequent (off-line) clean-up for the analysis of non-spiked samples showed that the efficiency of PLE was similar to or better (recoveries in the range 83-133%, as calculated for the endogenous analytes) than for the other two extraction methods assayed.

Analytic Sample Preparation Methods↗
PubMed2006

Improved single-drop microextraction for high sensitive analysis.

This paper described a simple approach to prepare a small bell-mouthed extraction device for single-drop microextraction (SDME). Analytical sensitivity was improved by increasing the suspended acceptor volume. Because of the increased contact area and the rough inner surface of the extraction device, the stability of drop was markedly increased. The merits of the proposed method were demonstrated by using 1-octanol as extractant and with cyanazine, simazine and atrazine as model compounds. The related parameters and the effect of humic acid were systematically investigated. Under the optimized extraction conditions, the linear range, detection limit (S/N=3) and precision (RSD, n=6) were 0.2-50, 0.06microgL-1, 5.7% for cyanazine, 0.1-25, 0.03microgL-1, 6.7% for simazine, and 0.15-37.5, 0.04microgL-1, 5.0% for atrazine, respectively. The established method was applied to determine the target compounds in four real water samples, and the satisfactory spiked recoveries at two concentration levels were obtained. Moreover, the comparison of the proposed SDME with the traditional SDME was performed. These results indicated that the proposed improvement made SDME be a competitive analytical tool and an alternative of the traditional methods for the analysis of organic pollutants at trace level.

Analytic Sample Preparation Methods↗
PubMed2006

Sample preparation for serum/plasma profiling and biomarker identification by mass spectrometry.

In this article, we present an overview of the different strategies for sample preparation for identification by mass spectrometry (MS) of biomarkers from serum and/or plasma. We consider the effects of the variables involved in sample collection, handling and storage, and describe different approaches for removal of high abundance proteins and serum/plasma fractionation. We review the advantages and disadvantages of such techniques as centrifugal ultrafiltration, different formats for solid phase extraction, organic solvent extraction, gel and capillary electrophoresis, and liquid chromatography. We also discuss a variety of current proteomic methods and their main applications for biomarker-related studies.

Analytic Sample Preparation Methods↗