scholarly journals Determination of Niacin in Food Materials by Liquid Chromatography Using Isotope Dilution Mass Spectrometry

2007 ◽  
Vol 90 (4) ◽  
pp. 1084-1089 ◽  
Author(s):  
Robert J Goldschmidt ◽  
Wayne R Wolf
Keyword(s):  
Liquid Chromatography ◽  
Reference Materials ◽  
Isotope Dilution ◽  
Solid Phase ◽  
Multiple Reaction Monitoring ◽  
Isotope Dilution Mass Spectrometry ◽  
Water Soluble ◽  
Relative Standard ◽  
Interference Problems

Abstract The availability of deuterium-labeled nicotinic acid makes stable isotope dilution mass spectromerty (MS) coupled with liquid chromatography (LC) an attractive option for the determination of the water-soluble B-vitamin niacin in food samples. A method was developed based on acid digestion, solid-phase extraction with a strong cation exchange column, and reversed-phase chromatography with a C18 column. Detection is by positive ion electrospray MS. Analysis in selected ion recording mode is subject to interference problems similar to those found with other LC determinations of niacin, but the additional selectivity of multiple reaction monitoring mode largely eliminates interference problems. The method was applied to 6 different food matrixes and to appropriate reference materials, including milk samples with niacin levels near 1 ppm. The method exhibited good accuracy, based on levels obtained for the reference materials, and relative standard deviations in the range of 0.55%.

scholarly journals Determination of Clopidol Residues in Chicken Tissues by Liquid Chromatography: Collaborative Study

2003 ◽  
Vol 86 (4) ◽  
pp. 685-693 ◽  
Author(s):  
Guo-Fang Pang ◽  
Yan-Zhong Cao ◽  
Chun-Lin Fan ◽  
Jin-Jie Zhang ◽  
Xue-Min Li ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Solid Phase ◽  
Collaborative Study ◽  
Reversed Phase ◽  
Method Performance ◽  
Chicken Muscle ◽  
Relative Standard

Abstract Eighteen laboratories participated in a collaborative study on the determination of clopidol residues in chicken muscle tissues by liquid chromatography. Of these, results from 16 laboratories which rigorously followed the method were subjected to statistical analysis. The method performance was assessed by all participants using 14 samples of chicken muscle fortified at concentrations ranging from 0.1 to 5.0 mg/kg. In addition, 9 participants each reported results for 6 clopidol-incurred samples in chicken muscle. Test portions were extracted with acetonitrile, and the extracts were purified with alumina and anion exchange resin solid-phase extraction cartridges in sequence. Clopidol was separated by reversed-phase liquid chromatography and quantified at 270 nm. Average recoveries ranged from 81.8 to 85.4%, reproducibility relative standard deviation (RSDR) ranged from 11.9 to 22.6%, and repeatability relative standard deviation (RSDr) ranged from 9.9 to 15.1%. For clopidol-incurred samples at concentrations of 0.100–0.687 mg/kg, the mean determination value range was 0.099–0.659 mg/kg; RSDR was 12.6–19.8%, RSDr was 3.1–8.5%; and HORRAT values were 0.7–1.1. The accuracy and precision of the method are in conformity with the requirements specified by AOAC INTERNATIONAL. The method was adopted Official First Action in April 2003.

A Simple and Sensitive Dispersive Micro-Solid-Phase Extraction Coupled with High-Performance Liquid Chromatography for Quantification of Honokiol and Magnolol in Complex Matrices

2020 ◽  
Vol 103 (5) ◽  
pp. 1406-1411
Author(s):  
Chu Chu ◽  
Jing Li ◽  
Shan Wang ◽  
Lvnan Weng ◽  
Luyi Jiang ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Solid Phase Extraction ◽  
High Performance ◽  
Solid Phase ◽  
Water Soluble ◽  
Phase Extraction ◽  
Patent Medicines ◽  
Chinese Patent

Abstract Background Honokiol and magnolol were considered as markers for the analysis of Cortex Magnoliae Officinalis, its related Chinese Patent Medicines and their metabolites. However, the determination of these two analytes in a water-soluble sample is difficult and therefore requires a more efficient method. Objective To develop a sensitive method for the determination of honokiol and magnolol in a water-soluble sample for better quality control of Cortex Magnoliae Officinalis and its related Chinese Patent Medicines. Method In this work, a combination of dispersive micro-solid-phase extraction (DMSPE) and high-performance liquid chromatography (HPLC) has been developed for simultaneous preconcentration and determination of honokiol and magnolol in complex bio-samples. Several experimental factors affecting the extraction efficiency were optimized by single factor test. Results Under the optimized extraction conditions, the proposed method exhibited good linearity of not less than 0.9998, satisfactory precision with relative standard deviation of less than 1.3%, and acceptable mean recoveries of 97.3% and 101.5% for honokiol and magnolol, respectively. Furthermore, the method exhibits extremely high sensitivity with detection limits of 0.0097 and 0.0231 ng/mL, which is even more sensitive than those methods developed by MS. Conclusions The method established in this study is fast, economic, accurate, easy to operate, and importantly well suited to the extraction and analysis of honokiol and magnolol in a real complex sample matrix.

scholarly journals Determination of Seventeen Polar/Thermolabile Pesticides in Apples and Apricots by Liquid Chromatography/Mass Spectrometry

2003 ◽  
Vol 86 (3) ◽  
pp. 612-622 ◽  
Author(s):  
Jitka Zrostlíková ◽  
Jana Hajšlová ◽  
Tomáš Kovalczuk ◽  
Radim Štěpán ◽  
Jan Poustka
Keyword(s):  
Liquid Chromatography ◽  
Ion Trap ◽  
Solid Phase ◽  
Reversed Phase ◽  
Simple Liquid ◽  
Liquid Chromatography Mass Spectrometry ◽  
Hydrophilic Lipophilic Balance ◽  
Relative Standard ◽  
Mass Spectrome

Abstract A simple liquid chromatography/mass spectrome-try (LC/MS) approach for the determination of widely used representatives of polar/thermolabile pesticides in fruits was developed and validated. The group of pesticides comprised benzimidazoles and azoles (carbendazim, thiabendazole, imazalil, propiconazole, prochloraz, epoxiconazole, flusilazole, tebuconazole, bitertanol); N-methylcarbamates (carbaryl, carbofuran, methiocarb); and phenylureas and benzoylphenylureas (linuron, diflubenzuron, triflumuron, teflubenzuron, flufenoxuron). Matrixes (apple, apricot) were extracted with acetonitrile and crude extracts were cleaned up by solid-phase ex-traction (SPE) using either mixed cation exchange or hydrophilic lipophilic balance cartridges. LC separation of pesticides was performed on a reversed-phase column, Discovery C18. Electrospray ionization and ion trap MS/MS detection were applied. For most pesticides, overall recoveries ranged from 75 to 122%, and repeatability (as relative standard deviation) from 5 repetitive determinations of recovery ranged from 3 to 21%. Carbofuran was the only compound for which recovery was not satisfactory due to its loss in the SPE cleanup step. Limits of detection were 0.1–3 μg/kg for benzimidazole and azole fungicides and carbamate insecticides. For urea insecticides, detection limits were slightly higher (3–10 μg/kg).

scholarly journals Determination of Niacin in Infant Formula by Solid-Phase Extraction/Liquid Chromatography: Peer-Verified Method Performance–Interlaboratory Validation

2002 ◽  
Vol 85 (3) ◽  
pp. 654-664 ◽  
Author(s):  
Denis E LaCroix ◽  
Wayne R Wolf ◽  
G William Chase
Keyword(s):  
Liquid Chromatography ◽  
Standard Deviation ◽  
Reference Material ◽  
Infant Formula ◽  
Solid Phase ◽  
Phase Extraction ◽  
Relative Standard ◽  
Interlaboratory Validation ◽  
Extraction Liquid

Abstract This paper reports the results of the interlaboratory peer validation study of AOAC Peer-Verified Method (PVM) 1:2000 for the determination of niacin in infant formula by solid-phase extraction/liquid chromatography. We have used a Data Quality Objectives (DQO) approach to address not only method variability and robustness but also accuracy of data through the use of an appropriate reference material in conjunction with the interlaboratory validation study. Our DQO included the following: (1) statistical agreement of analytical results and quantitative recovery between 2 collaborating laboratories; (2) the repeatability relative standard deviation (RSDr) values and the HORRAT (Horwitz ratio) obtained (1.07), which satisfied the criteria of the Horwitz “limits of acceptability” at the analyte level present; (3) validation of lack of interference; and (4) accuracy agreement within assigned values for a certified reference material. National Institute of Standards and Technology Standard Reference Material (NIST SRM) 1846 Infant Formula, with a certified value of 63.3 ± 7.6 μg/g for niacin content, was used as a test material for collaborative study and accuracy assessment. Niacin values obtained by the originating laboratory were 59.7 ± 4.0 μg/g (95% confidence interval [CI] = 1.4 μg/g with a relative standard deviation [RSD] of 6.7%) and by the peer laboratory were 56.6 ± 6.6 μg/g (95% CI = 4.1 μg/g, with an RSD of 11.7%). Statistical evaluation using the means equivalence test showed that nicotinic acid values obtained by the peer laboratory were equivalent to those values obtained by the originating laboratory. Linear calibration curves and quantitative recovery were obtained. Integration of the PVM process with a readily available certified reference material gives the user confidence in the accuracy of the data generated by the method through traceability to the reference material used.

scholarly journals Determination of Flumequine in Channel Catfish by Liquid Chromatography with Fluorescence Detection

1999 ◽  
Vol 82 (3) ◽  
pp. 614-619 ◽  
Author(s):  
Steven M Plakas ◽  
Kathleen R El Said ◽  
F Aladar Bencsath ◽  
Steven M Musser ◽  
Calvin C Walker
Keyword(s):  
Liquid Chromatography ◽  
Fluorescence Detection ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Solid Phase ◽  
Signal To Noise Ratio ◽  
Methanol Solution ◽  
Signal To Noise ◽  
Relative Standard

Abstract Rapid methods are described for determination of flumequine (FLU) residues in muscle and plasma of farm-raised channel catfish (Ictalurus punctatus). FLU residues were extracted from tissues with an acidified methanol solution, and extracts were cleaned up on C18 solid-phase extraction cartridges. FLU concentrations were determined by liquid chromatography (LC)using a C18 analytical column and fluorescence detection (excitation, 325 nm; emission, 360 nm). Mean recoveries of FLU from fortified muscle were 87–94% at 5 levels ranging from 10 to 160 ppb (5 replicates per level). FLU recoveries from fortified plasma were 92–97% at 5 levels ranging from 20 to 320 ppb. Limits of detection (signal-to-noise ratio, 3:1)for the method as described were 3 and 6 ppb for muscle and plasma, respectively. Relative standard deviations (RSDs) for recoveries were ≤12%. Live catfish were dosed with 14C-labeled or unlabeled FLU to generate incurred residues. Recoveries of 14C residues throughout extraction and cleanup were 90 and 94% for muscle and plasma, respectively. RSDs for incurred FLU at 2 levels in muscle and plasma ranged from 2 to 6%. The identity of FLU in incurred tissues was confirmed by LC/mass spectrometry.

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