Search results for "Detection limit"
showing 10 items of 810 documents
Determination of phytic acid and its degradation products by ion-pair chromatography (IPC) coupled to inductively coupled plasma-sector field-mass sp…
2004
We developed a method for the determination of phytic acid (IP6) and its degradation products (IP1-IP5) by ion-pair chromatography coupled to a double focussing inductively coupled plasma-sector field-mass spectrometer (ICP-SF-MS). For the detection of the phosphorus species a mass resolution (m/Δm) of 4000 was needed in order to separate the 31P+ signal from the interfering clusterions. The separation of the six phosphorus species was enabled by a gradient elution using tetrabutylammonium hydroxide (TBA) as ion-pair reagent. Calibration data were reported and a detection limit of 230 ng g−1 for IP6 could be obtained. The method was firstly proved for a hydrolyzate of commercially available…
Study on the determination of trace rhenium (VII) by the adsorption differential pulse polarography
1989
The determination of trace rhenium (VII) by differential pulse polarography in the system of H2SO4-(NHsOH)2 · H2SO4-TeO2−4 is markedly improved by the addition of Nitron, which is adsorbed on the surface of mercury electrode. The limit of detection is down to 2 × 1010 M. The adsorptive peak potential is −0.80 V (vs. SCE). In the ranges of 5 × 1010—10−8, 1 × 10−5—10−7 and 1 × 10−7—10−6M, there are good linear relationships between the peak current increment and the concentration, of which the relative standard deviations are 9.5, 6.6, 1.8% respectively with the correlation coefficients of linear regression of 0.995–0.999. The results relating to this polarographic wave show that it is an ads…
Determination of ascorbic acid in asparagus by differential pulse polarography
1995
A useful method for the determination of ascorbic acid in a vegetable product (asparagus) by differential pulse polarography has been set up and evaluated. Extraction and instrumental conditions were optimized. The analytical parameters are: linearity (0–18.18 μg/ml); detection limit (0.182 μg/ml); instrumental and method precision (2.77% and 4%, respectively); accuracy (96.9–113.4%). These data show that the method is sufficiently sensitive, reliable and accurate. It was also compared with the official fluorometric AOAC method.
Green, rapid and simultaneous determination of ‘alternative preservatives’ in cosmetic formulations by gas chromatography-mass spectrometry
2022
Abstract Some hydroxylated compounds commonly used in cosmetic formulations including short chain glycols, benzylic alcohols, and organic acids show antimicrobial activity, although they are not considered as preservatives according to the existing European legislation. These ‘alternative preservatives’ are not exempt of potential side-effects for cosmetics users. The aim of this work is to develop a simple and affordable analytical method useful for the simultaneous and green determination of fourteen compounds used as ‘alternative preservatives’ in cosmetic samples with different matrices. The proposed method allows a rapid sample preparation by simple dissolution or dispersion of the sam…
FTIR determination of Aspartame and Acesulfame-K in tabletop sweeteners.
2004
Two different strategies for sweeteners determination in tabletop samples by Fourier transform middle-infrared (FTIR) spectrometry, an off-line and a fully mechanized extraction of Aspartame and Acesulfame-K with different mixtures of chloroform and methanol, have been developed. The off-line method involves the extraction of both active principles by sonication of samples with 25:75 v/v CHCl3/CH3OH and direct measurement of the peak height values at 1751 cm(-1), corrected using a baseline defined at 1850 cm(-1) for Aspartame, and measurement of the peak height at 1170 cm(-1) in the first-order derivative spectra, corrected by using a horizontal baseline established at 1850 cm(-1), for Aces…
Automated determination of reboxetine by high-performance liquid chromatography with column-switching and ultraviolet detection.
2000
A fully automated method including column-switching and isocratic high-performance liquid chromatography (HPLC) was developed for quantitative analysis of the new antidepressant reboxetine, a noradrenaline reuptake inhibitor. After serum injection into the HPLC system and on-line sample clean-up on a silica C8 (10x4.0 mm I.D.) clean-up column with an eluent consisting of 2.5% acetonitrile in deionized water, the chromatographic separation was performed on an analytical column (Lichrospher CN; 250x4.6 mm I.D.) with an eluent of acetonitrile-aqueous potassium phosphate buffer (0.008 M, pH 6.4) (50:50). The UV detector was set at 273 or 226 nm. The limit of quantification was about 15 ng/ml at…
Quality control of pharmaceuticals containing clenbuterol by thermal lens spectrometry.
1996
An ultrasensitive absorptiometric procedure for the determination of clenbuterol in pharmaceutical preparations was developed. Clenbuterol was diazotized with nitrite and coupled with 1-(naphthyl)ethylenediamine, and the absorbance of the azo dye formed was measured by both spectrophotometry and ultrasensitive thermal lens spectrometry (TLS). The TLS limit of detection was 1.5 ppb, 14-fold lower than with a Hewlett-Packard diode array spectrophotometer. Thus, the TLS procedure can be advantageously applied to quality control of clenbuterol at the individual dose level and in small samples. Repeatability as relative standard deviation was 1.5% (50 ppb, n = 6).
Determination of abamectin in citrus fruits by liquid chromatography-electrospray ionization mass spectrometry.
2000
Liquid chromatography coupled to electrospray mass spectrometry (LC-ES-MS) with positive ion detection was used to determine abamectin in oranges. MS conditions were optimized to achieve maximum sensitivity. The main ion for abamectin was [M+Na]+ at a fragmentor voltage of 180 V. Abundant structural information can be obtained at different fragmentor voltages. The detection limit for the standard solution was 12 pg injected, and good linearity and reproducibility were observed. Abamectin residues were extracted using matrix solid-phase dispersion. Orange samples were homogenized with C18 bonded silica placed onto a glass column and eluted with dichloromethane. Recoveries of the abamectin fr…
Simultaneous determinations of zirconium, hafnium, yttrium and lanthanides in seawater according to a co-precipitation technique onto iron-hydroxide.
2013
Very low concentrations (pg mL(-1) or sub-pg mL(-1) level) along with the high salinity are the main problems in determining trace metal contents in seawater. This problem is mainly considered for investigations of naturally occurring YLOID (Y and Lanthanides) and Zr and Hf in order to provide precise and accurate results. The inductively coupled plasma mass spectrometry (ICP-MS), both in high and low resolution, offers many advantages including simultaneous analyses of all elements and their quantitative determination with detection limits of the order of pg mL(-1). However in the analysis of YLOID in seawater, a better determination needs an efficient combination of ICP-MS measurement wit…
Recent developments in and applications of resonance ionization mass spectrometry
1999
Resonance Ionization Mass Spectrometry (RIMS) has nowadays reached the status of a routine method for sensitive and selective ultratrace determination of long-lived radioactive isotopes in environmental, biomedical and technical samples. It provides high isobaric suppression, high to ultra-high isotopic selectivity and good overall efficiency. Experimental detection limits are as low as 106 atoms per sample and permit the fast and sensitive determination of ultratrace amounts of radiotoxic contaminations. Experimental arrangements for the detection of different radiotoxic isotopes, e.g. 236–244Pu, 89,90Sr and 99Tc in environmental samples are described, and the application of RIMS to the ul…