Rapid and Quantitative Blood Analysis for Free Fatty Acids by Chemical Ionization Mass Spectrometry

Abstract

A quantitative analysis of fatty acids in micro-samples of dried blood spots by chemical ionization mass spectrometry has been developed. Isotope determination was used as the quantitating technique using the corresponding deuterium labeled internal standards. The procedure yields excellent precision and accuracy as demonstrated by the analysis of known fatty acid mixtures and of both C_12:0 to C_18:0 acids and phytanic acid in the blood from patients.     

A Study of Adrenaline-Dansyl Derivatives for Separation by Liquid Chromatography. Application to Blood Plasma Analysis

Abstract

A plausible mechanism and explanation for the instability of the tri-dans adrenaline has been given. The formation of dimeres accompanied by the loss of one dansyl moiety per adrenaline molecule seems to take place upon U.V. irradiation. This is followed by an increase in fluorescence due to release of strain (steric hindrance) on the molecule.

The feasibility of the pre-column dansylation. technique for the analysis of adrenaline and noradrenaline in plasma samples has been demonstrated. Taking necessary precautions, quantitation in the low nonagram region is possible with a reproducibility     

Determination of Allantoin in Drug Preparations by Quantitative High Performance TLC

Abstract

A densitometric TLC method was developed for the quantification of allantoin in creams and suppositories used to treat vaginal infections. Allantoin was extracted with water at elevated temperature, diluted to a known volume, and separated by HP silica gel TLC. Allantoin was detected by spraying with p-dimethylamine-benzaldehyde reagent. The absorption of standards and samples was compared by in situ scanning. Recoveries of allantoin from authentic samples ranged from 96–102%, except for one sample that assayed high. The accuracy of the method was demonstrated by standard addition analysis of this sample.     

A Simplified Extraction for Mexiletine from Serum and Analysis by High Performance Liquid Chromatography

Abstract

The analysis of mexiletine by High Performance Liquid Chromatography (HPLC) requires organic extraction followed by evaporation of the organic solvent. Calibration curves must be prepared using standards in drug-free serum. This procedure has been simplified by using a back extraction of the mexiletine from serum. Calibration curves can then be more quickly prepared since good agreement can be obtained using standards in hydrochloric acid (HCl) instead of having to prepare standards in serum with the time-consuming necessity of having to extract these standards.     

An Experimental Evaluation of a New Commercial Viscometric Detector for Size-Exclusion Chromatography (SEC) Using Linear and Branched Polymers

Abstract

Herein are reported some findings on the application of a new type of continuous automatic viscometer, in parallel with a differential refractometer, as a detector system for SEC. A universal calibration is required for the instrument and two methods of construction are applicable. The first is the customary peak-position calibration using polymer standards of narrow molecular-weight distribution and the second uses a single broad standard of known [Mbar]_w and [Mbar]_n. The two types of calibration are shown to give nearly-identical values of molecular weight when used to process chromatograms obtained from various linear homopolymer standards of varying chemical composition. These values compare favourably with those quoted by the suppliers of the polymer standards. One of the more powerful features of this instrumentation, namely its potential for estimating accurate molecular weights of branched polymers, is demonstrated by analysis of a series of branched polyvinylacetates prepared by a conventional bulk, free-radical polymerisation procedure. The calculation of the degree of chain branching is discussed. Another particular feature of the viscometer detector, its ability to indicate the presence of low concentrations of high-molecular-weight impurity in polymer samples, is also shown.     

Phase Solubility Analysis of Some Organophosphate Pesticides

Abstract

Phase solubility analysis (PSA) was applied to the determination of azinphos-ethyl and - methyl standards. The presence of 0.5% purity was detected by the method. A linear cumulative effect was obtained when known amounts of two impurities were added to standards of both organophosphate materials which were then analyzed by the phase solubility method.     

Determination of Calcium,Magnesium and Phosphorus in Small Amounts of Rat Tissues by Direct Current Plasma-(DCP)-Atomic Emission Spectrometry

Abstract

A procedure is described for simultaneous determination of Ca, Mg and P in small amounts (a few mg) of tissues by use of Direct Current Plasma-Atomic Emission Spectrometry. The samples were analyzed by using matrix matched standards. The necessity to use high-purity acids for decomposition of samples is demonstrated. The method was tested on four different reference samples.

The accuracies for the elements were satisfactory (93–103%). The within-run and between-run precisions were 0.9–6.8 and 0.9–8.6%, respectively.

The method may be used for determination of other elements.     

Practical Microbore Column HPLC: System Development and Drug Applications

Abstract

Commercially available packed microbore columns have been used to demonstrate the potential of microbore high performance liquid chromatography (micro-LC) systems. The necessity of optimizing the chromatographic system for micro-LC is demonstrated using sulfa drugs and antibiotic standards, and some of the advantages of micro-LC such as high mass sensitivity are shown. Finally micro-LC has been used for the determination of two drugs, reserpine and trichlormethiazide in biological fluids.     

Topochemical polymerisation of assembled diacetylene macrocycle bearing dibenzylphosphine oxide in solid state

Novel diacetylene macrocycles 1 and 2 bearing dibenzylphosphine oxide were synthesised via Eglinton acetylenic intramolecular coupling. The X-ray analysis of crystals of macrocycles 1 and 2 demonstrated that the better-aligned tubular supramolecular structure was formed in macrocycle 1 than in macrocycle 2, which provided the possibility of diacetylene topochemical polymerisation in solid state of macrocycle 1. UV–vis, Raman spectroscopy and X-ray analysis indicated that the crystals of macrocycle 1 could undergo topochemical diacetylene polymerisation only on their surface by light irradiation; differential scanning calorimetry, solid-state ¹³C NMR spectroscopy and solubility test demonstrated that the crystals of macrocycle 1 could undergo diacetylene topochemical polymerisation inside solid by heat. As expected, based on the topological analysis of crystal structure, the crystals of macrocycle 2 could not undergo diacetylene topochemical polymerisation either by light irradiation or heat.     

Fast Analysis of Capillary Electrochromatography with Non-Porous ODS as the Stationary Phase

ABSTRACT

High-speed capillary electrochromatography was developed on both short and long packed columns with 2 μm non-porous ODS as the stationary phase. Factors that affect the analysis time of samples, such as voltage, electrolyte concentration, pH and organic modifier concentration in the mobile phase, were studied systematically. Fast analysis of aromatic compounds within 13 seconds was realized with column efficiency of 573,000 plates/m and a R.S.D.% of the retention times of all components in 8 consecutive injections below 1.0%, which demonstrated the high efficiency and high reproducibility of such a technique. In addition, DNPH derived aldehydes and ketones in both standards and environmental samples were separated with high speed.     

Quantitative LC-ESI-MS Analysis for Pesticides in a Complex Environmental Matrix Using External and Internal Standards

Abstract

Quantitative liquid chromatography electrospray mass spectrometry (LC-MS) analysis for pesticides in a complex environmental matrix using external and internal standard calibration was investigated. Various approaches to introducing different internal standard compounds to address quantitative errors associated with signal suppression were also examined. The study involved the analysis of pesticides in wheat hay matrix samples using three kinds of internal standard compounds: deuterium labeled (D₃), carbon-13 (singly labeled), and structural analogs (derivatives) of the target analytes. Introduction of the internal standard by volumetric addition and direct post-column infusion were also studied and compared.

Isotopically labeled internal standards (i.e. D₃- ¹³C-) were found to be effective in correcting quantitative errors associated with signal suppression. The application of singly labeled ¹³C compounds may result in nonlinear calibration due to mass interference with the target analyte species. The interference may be compensated by using quadratic curve-fitting or subtraction of the interfering component. Although ineffective as volumetric internal standards, structural analogs can be effective in compensating for signal suppression when introduced into the LC effluent by continuous post-column infusion. Furthermore, the post-column introduction method allows the application of a single internal standard compound for the quantification of each analyte in a multi-component mixture.

The use of internal standards can be effectively incorporated into residue analysis development methods for pesticides in environmental matrices. High accuracy and reproducibility can be achieved while improving method efficiency by reducing the need for comprehensive sample clean-up.     

Separation of Diethylstilbestrol and Derivatives in Biological Fluids and Tissues by High Pressure Liquid Chromatography

Abstract

A method was developed to identify radiolabeled DES and DES metabolites in biological fluids and tissues. After a rapid initial clean-up step, the biological samples were analyzed with a single-column, reversed-phase, highpressure liquid chromatography system. The parent compound and metabolites were simultaneously resolved and tentatively identified by comparing their retention times to those of known standards. Positive identification of some metabolites was achieved by field-desorption and capillary-column mass-spectrometric analysis. The method was found to be rapid and reproducible, and sample recovery was >80%.     

Evaluation and Application of a Commercial Single Capillary Viscometer System for The Characterization of Molecular Weight Distribution and Polymer Chain Branching

Abstract

The objective of this paper is to critically evaluate the performance of the newly introduced Millipore Waters GPC-viscometer system. In particular, the capabilities of the data analysis methodology are evaluated and limitations are identified. Potential modifications to improve the data analysis methodology and to make it more user friendly are suggested. The characterization of molecular weight, molecular weight distribution and polymer branching for polymer standards and polymers of commercial interest are reported.     

Multicomponent Analysis Of Environmental Matrices

Abstract

The paper reviews several modalities of multicomponent analysis, namely: multilinear regression by using single or multiple standards, non-linear optimization systems by using the Gauss-Newton or the Simplex methods and factor analysis, which have been used by the authors in recent papers.

These multicomponent methods have been applied to environmental samples by different analysis techniques, such as UV- visible spectrophotometry, fluorimetry, polarography-voltametry, simultaneous kinetic processes. monitoring of liquid-liquid extraction processes and HPLC (resolution of overlapped peaks). In this way, the advantages and limitations of the methodology of multicomponent analysis are shown.     

Chemical Analyses of Canadian Reference Samples: SY-2 and SY-3

Abstract

Chemical analyses of the major and some of the minor constituents are reported for two new Canadian silicate rock standards recently introduced by the Department of Energy, Mines and Resources. To date quantitative chemical analyses have not yet been reported for these samples. The compositions of these rocks offer a useful range of values that are not currently covered by existing silicate rock standards.     

Isolation of Lipophilic Persistent Organic Pollutants From Human Breast Milk

Background: Lipid removal from biological samples can be achieved by addition of concentrated sulfuric acid. However, certain persistent organic pollutants (POPs) such as chlorophenols are decomposed by sulfuric acid treatment and, thus, a more gentle lipid reduction method is needed for extraction of many environmental contaminants from biological samples. Membrane dialysis extraction (MDE) is a non-disruptive method to extract POPs from biological matrices.

Methods: Human breast milk samples were spiked with radiolabelled p,p′-dichlorodiphenyl trichloroethane ([C-14]-DDT) as a POP proxy and extracted using solid phase extraction (SPE). The extracts obtained were dialyzed by MDE in low-density polyethylene tubings containing a mixture of n-hexane and dichloromethane for 24 h, 48 h, or 72 h.

Results: The lipid content was reduced by 86.2% after one dialysis cycle of 24 h using MDE, and 87.1% recovery of the [C-14]-DDT standard was obtained. The DDT recovery could be further increased up to 96.3% and 98.1% by repeating the dialyses for one or two more cycles, respectively. However, the increased [C-14]-DDT recovery includes a concomitant increase in lipid carryover from 13.8% with one dialysis cycle to 22.1% with three cycles.

Conclusion: An SPE procedure for extracting POPs from breast milk and dialytic conditions for isolation of the extracted POP with minimal lipid carryover was established. The method is nondestructive and acceptable recoveries can be obtained within a single solvent shift as demonstrated by spiking standards. The lipid carryover was minimized, and the method may be considered for lipid removal before HPLC or GC analysis of environmental contaminants.     

Analysis of the Sulfonylurea Herbicide Metsulfuron-Methyl and Its Metabolites in the Soil of Cereal Crops. Comparative Analytical Chemistry of the Sulfonylureas

Abstract

For the analysis of metsulfuron-methyl in the crop soils with a sensitivity limit of 0.3 μg kg^?1 dry soil, in the soil extract metsulfuron-methyl was separated from its soil metabolites and the soil impurities by repeated thin-layer chromatographies (TLC). In the cleaned soil extract, diazomethane transformed metsulfuron-methyl 1 into N,N′ -dimethyl metsulfuron-methyl 2 (methyl 2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)methylamino]carbonyl]methylamino]sulfonyl]benzoate). In the gas-liquid chromatograph with detection by electron capture (GC-EC) and in the combined gas chromatograph-mass spectrometer (GC-MS), 2 was transformed into 1-dioxy-2-N-methyl-3-keto-1,2-benzisothiazole 3 which was measured by GC-EC with confirmation by GC-MS. The metsulfuron-methyl soil metabolites 2-sulfonamido-methylbenzoate 6, 1-dioxy-3-keto-1,2-benzisothiazole (saccharin) 7 and 2-sulfonamidobenzoic acid 8 were analyzed in the soil of winter wheat crops by a procedure similar to the one for metsulfuron-methyl. After their separation and purification in the soil extracts by TLC, 7 and 8 were methylated, and analyzed as 3 in the GC-EC and GC-MS apparatus where the generated 6 was quantitatively transformed into 3; 6 was analyzed as such with the GC and GC-MS apparatus wherein it was transformed into 3. The sensitivity limit for each metabolite was 0.3 μg of equivalents of metsulfuron-methyl kg^?1dry soil. The syntheses of the analysis standards of the metsulfuron-methyl derivatives 2 and 3, and of the metsulfuron-methyl metabolites 6, 7 and 8 are described. The transformation pathways of metsulfuron-methyl and of its derivatives are different from those of the pyridine-pyrimidine sulfonylurea herbicides flupyrsulfuron-methyl and rimsulfuron. The soil analysis of a sulfonylurea -by means of one of its transformation product- needs a previous study of the chemical reactivity of the sulfonylurea. This leads to the analysis procedures for the main soil metabolites of the sulfonylurea.     

Determination of Atrazine in Vegetable Samples Using a Dipstick Immunoassay Format

A dipstick assay format for atrazine analysis in vegetable samples is described. The analytical method consists in a fast extraction procedure followed by a test based on the use of Immobilon-P strips as antibody coating support. The atrazine quantification was carried out measuring the dot colour by a spectrophotometer. Thus atrazine could be detected in a concentration range 0.16-475.0 µg L_{m 1} with an I₅₀ of 2.04 µg L _m1. For direct quantification of vegetable samples, those were extracted by blending 5 g in 10 mL of MeOH for 10 min followed by a vacuum filtration through 0.45 µm nylon filters. To avoid erroneous atrazine results, all samples and standards were run in 50% of MeOH which decreased the assay sensitivity by ten fold ( I₅₀ = 21.09 µg L_m1). Therefore, the proposed methodology was able to perform atrazine analysis under established EU MRL. The samples could be measured directly without any prior concentration or clean-up steps. Recoveries (75-105%) were in agreement with those obtained by a reference method (multiresidue extraction-GC/MS quantification). The feasibility of automated immunoreagent dispenser was also demonstrated.     

Determination of Residues of Chemotherapeutic and Antiparasitic Drugs in Food Stuffs of Animal Origin with Liquid Chromatography and UV/VIS Diode-Array Detection

Abstract

An HPLC method is described which enables the qualitative and quantitative analysis of residues of pharmacologically active substances in food stuffs of animal origin. Egg samples were spiked with the therapeutic drugs sulfapyridine and its N-acetyl metabolite, with ethopabat, chloramphenicol, meticlorpindol, metronidazol, ipronidazol, furazolidone and nicarbazin and with pyrazon and benzothiazuron as internal standards in the range of 0.02 to 0.1 mg/kg. The drugs were extracted with acetonitrile and purified by liquid-liquid partition steps. They were separated on a reversed phase column and detected with a multi-signal UV/Vis diode-array detector at 3 different wavelengths: 275, 315 and 360 nm. The peak's identity was confirmed by comparing retention times and UV spectra with those of standards. Peaks were checked for homogenity by comparing spectra at the peak's upslope, apex and downslope. The detection limit was in the range of 0.001 to 0.05 mg/kg.     

Sampling of Atmospheric Carbonyls with Small DNPH-Coated C18 Cartridges and Liquid Chromatography Analysis with Diode Array Detection

Abstract

Carbonyls in air are sampled using small DNPH-coated C18 cartridges and analyzed by liquid chromatography with diode array detection. Carbonyl structure confirmation is obtained by comparing diode array spectral scans of samples to the uv-visible spectra (190–600 nm) of some 20 carbonyl hydrazones recorded in the CH₃CN—H₂O eluent used for LC analysis. Analytical detection limits are 0.09–3.4 nanograms carbonyl and correspond to 0.14–1.24ppb in 60 L air samples. Accuracy was ±5% as measured for independently prepared hydrazone standards. The precision was 1–5% for multiple injections of hydrazone standards and 2–10% for replicate analysis of indoor and outdoor air samples. Excellent agreement was obtained in an interlaboratory comparison that included hydrazone standards as well as indoor air samples.

Cartridge collection efficiency has been tested over a range of conditions (sampling flow rate, volume of air sampled, presence of co-pollutants including photochemical oxidants) and is >0.95 for monofunctional carbonyls, unsaturated carbonyls, and alpha dicarbonyls. Carbonyl recovery by cartridge elution is >0.99 for all carbonyls tested. Examples of applications are given in the fields of atmospheric chemistry, indoor air pollution in museums, and outdoor air quality.