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David S. Hage. University ofNebraska, Lincoln. James D. Carr An Overview of Analytical Chemistry 1 Information Provided by Chemical Analysis 7. by David S. Hage and Lincoln James R. Carr. Analytical Chemistry and Quantitative Analysis presents concepts and procedures in a manner that reflects the. kipentoriber.tk: Analytical Chemistry and Quantitative Analysis ( ) by David S. Hage; James R. Carr and a great selection of similar New, Used.
They prepare and standardize solutions of a strong acid and base and then, using these standard solutions, carry out titrimetric analysis on a variety of test solutions.
Among these are an acid neutralizing capacity ANC measurement and a pH measurement on a sample of natural water that the students collected from one of the campus ponds.
An aliquot of the same water sample is submitted for ion chromatography. The IC analysis generates concentration data for five anions: fluoride, chloride, nitrate, phosphate, and sulfate. Working in pairs, students in the different lab sections generate about water samples collected from 6 sites on the campus— about 25 samples per site.
The ANC, pH, and ion concentration data for each site are entered on a spreadsheet. There are a sufficient number of data points to allow some simple data analysis. We spend a short time explaining the significance of each of these statistical measures. After obtaining all the data for the different collection sites we spend some time approximately one class period discussing the results.
We talk about the environmental significance of the ANC is the pond likely to become acidic if exposed to acid precipitation? We discuss why a natural water sample can have a pH near 7 but still have a large ANC. For the IC results we note which ponds have relatively high concentrations of one anion or another and ask students to identify possible sources of these ions e.
These data are generated and logged each year to provide a longitudinal data set in which we can see how the campus ponds change over time with respect to the parameters measured.
A number of review articles and books are available on the theory and applications of ion chromatography 17— Reports on the use of ion chromatography for detection of phosphate in beverages and to study the common ion effect have been published in this Journal 22, These include the eluent supply jar, the pump system, the injection system manual or auto-injection , the ion exchange column, a suppressor, the detection system, and the computer-controller, as shown in Figure 1.
Eluent Solutions Depending on whether one is analyzing for anions or cations, different eluent solutions are used. The most common eluent for anion analysis is a dilute buffer solution containing sodium bicarbonate and sodium carbonate. Alternatively, dilute aqueous sodium or potassium hydroxide may be used as the eluent. Since these eluents are conductive, the background signal is generally large with conductivity detectors. Although dilute eluents may be used directly with conductivity detectors, Figure 1.
Schematic of an ion chromatography system. Typically we use the bicarbonate—carbonate eluent system for anion analysis. A less costly option would be to make your own stock eluent solutions using high-purity reagents and Type I water. In cation analysis, the eluent is normally a dilute acid solution—usually a mineral acid, but other acids may also be used depending on the analytical task.
Again, we use a commercial metal-free-grade acid solution and dilute it to appropriate levels with Type I water. Pump Systems Several instrument manufacturers offer modular ion chromatography systems that operate either in isocratic-only mode or with both isocratic and gradient capabilities. While isocratic IC is the standard choice for routine ion analysis, the gradient technique enables the separation and analysis of a considerably wider range of anions and is essential for successful analysis of organic anions carboxylates, for example.
The gradient technique, however, has limited use for cation analysis. We use the IC instrument mainly to support our teaching program and the isocratic mode of operation has been satisfactory for most of our purposes. Recently we have begun studies involving analysis of organic anions, in which we are making use of the gradient capabilities of the instrument. However, in view of the limited use we have made of the gradient technique within the past year and a half, our opinion is that the download of an isocratic system is sufficient for most teaching purposes.
If the instrument is to have significant use in research projects, a combined isocratic— gradient pump system is desirable. Injection Systems While instruments equipped only for manual injection of samples are less costly, our IC system is equipped with an autosampler that can accommodate 60 samples in one run. We have found this feature to be invaluable. It allows us to run all the samples from a lab section in a single overnight run, and we feel that the convenience of an autosampler well justifies its cost.
We note that the autosampler accessory also requires the use of specialized sample containers disposable plastic tubes with caps , which introduces some additional operational cost. Ion Exchange Columns For anion analysis the ion exchange column is usually a resin with attached alkyl quaternary ammonium chains.
When the bicarbonate—carbonate eluent flows through these columns the eluent anions form the counter ions to the fixed ammonium ions on the resin. When solutions containing other inorganic anions are eluted into the column, they compete with the eluent anions for the fixed positive centers on the resin.
Depending on how well or how poorly these anions compete with the eluent anions for positive charge centers on the resin, they are carried more slowly or more quickly through the column. In this case the ion exchange column is composed of a resin carrying fixed negative charge centers—sulfonate, carboxylate, etc.
The acidic eluent solution provides protons as the counter ion to these negative charge centers. Then, when other cations are eluted through the column, they compete with the protons for the fixed negative charge centers on the resin. Attenuated total reflection A and surface second harmonic generation were both considered as approaches for detection in immunoassays A Continued work in the development of immunoassay methods employing metal carbonyl complexes as labels was also reported A Since the review, there has been a rapid expansion in publication that dealt with the use of CE in routine hospital laboratories and in specialized clinical settings.
This review is not intended to be comprehensive of all published papers in the review period; rather, the author has tried to select those papers that the author feels are significant to clinical diagnosis of diseases. In addition to the previous topical review covering the literature cited by Chemical Abstracts from October to October B1 , there were numerous clinical chemistry-related reviews published during this review period.
Diagnosis of Metabolic Disorders. Grimshaw and co-workers evaluated the use of CE for quantitative analysis of hyaluronan in human synovial fluid. The polymeric hyaluronan was first hydrolyzed to tetrasaccharide by testicular hyaluronidase. Then, the product together with an internal standard was separated and detected by CE at nm. They found that the changes in tetrasaccharide concentration correlated with the arthritic disease state of a joint B23, B Adenylosuccinate lyase ASase defect causes secondary autism and psychomotor retardation in early childhood.
In all body fluids of these patients, two succinylpurine metabolites succinyladenosine and succinylaminoimidazole carboxamide riboside can be found that are normally not detectable by conventional methods.
Gross and coworkers developed a CE method for screening the disease. Untreated urine was injected into a fused-silica capillary filled with borate buffer pH 8. The two succinylpurine metabolites were detected at nm from urine of patients with ASase deficiency but not from the control samples. Their migration times were Methylmalonic acid MMA elevation is an established marker of cobalamin vitamin B12 deficiency.
In this method, phthalic acid was used as the background electrolyte and absorbance was monitored at nm.
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Sample preparation consisted of an ethyl acetate extraction, evaporation of the ethyl acetate, and resuspension in distilled water. The CE run time was R observed between the patients groups, and these differences appeared to be disease and age related B Hiraoka and coworkers used CZE to determine organic acids in cerebrospinal fluid from patients with various central nervous system CNS diseases B30, B They reported that the lactate and pyruvate levels in cerebrospinal fluid were elevated in patients with cerebral infarction and bacterial meningitis, whereas cerebrospinal fluid ascorbate was reduced mainly in inflammatory disorders of the CNS.
The above results indicated that analysis of cerebrospinal fluid by CE might be useful for the biochemical diagnosis of CNS disorders and for study of the mechanisms of these disorders. Hiraoka and co-workers applied CZE to determine uric acid UA in cerebrospinal fluid and concurrent sera from patients with various neuropsychiatric diseases. Such changes in the cerebrospinal fluid UA levels were independent of the free and total serum UA levels. Therefore, it was suggested that the determination of UA in cerebrospinal fluid might be valuable for investigating pathological conditions in the CNS B Jariego and Hernanz developed a reliable CE method for detection and quantitation of 10 organic acids methylmalonate, glutarate, 3-methylglutarate, N-acetylasparate, 2-aminoadipate, propionate, lactate, 2-oxoisovalerate, isovalerate, homogentisate in the screening of organic acidurias.
The method comprised direct application of diluted urine, electrophoretic separation at 29 kV, and UV detection at nm. Complete separation of organic acids was achieved within 10 min. They believed that the method was applicable for use in routine clinical laboratories B Shirao and co-workers also separated 12 organic acids oxalic, formic, malonic, fumaric, succinic, R-ketoglutaric, citric, acetic, pyruvic, lactic, isovaleric, and hippuric acids in urine.
The method was successfully applied to the determination of organic acids in urine and the method comparison with an organic acid analyzer B Dolink used CZE to separate the pathological metabolites phenyl pyruvate, 2-hydroxyphenyl acetate, phenyl lactate, and phenyl acetate from urine of phenylketonuric individuals.
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The separation was completed within 12 min. It was found that the differences in the content of these metabolites in urine were significant among a healthy man, a phenylketonuric newborn, and a phenylketonuric individual on a low-phenylalanine diet B Xu and co-workers applied CE to determine the iron level in human serum. A stable Fe II -1,phenanthroline complex was formed by adding 1,phenanthroline to the supernatant containing 2.
Copper, the major interference in serum with conventional spectrophotometric methods, was also converted into Cu II -1,phenanthroline complex under the same conditions. These two complexes were resolved completely by CE and detected quantitatively at nm. With this method, a single drop R Analytical Chemistry, Vol. Fernandez and co-workers examined the utility of CE for the separation of testosterone metabolites in liver microsomal incubates after a liquid-liquid extraction and preconcentration procedure.
The separation was achieved within 25 min. The proportion of the metabolites as determined by the method revealed the relative activity of cytochrome P enzymes in the microsomes. This technique was useful for the comparison of activity in normal and abnormal hepatic microsomes B Petucci and co-workers reported the use of CZE to identify and quantify low molecular mass compounds found in normal and uremic serum as well as in hemodialyzate fluid.
The method provided a single-step screening for more than 19 metabolites in less than 16 min. Serum samples from healthy individuals and from patients who were diagnosed with chronic renal failure were analyzed using a borate buffer system at pH 9. Moreover, each of these metabolites was present at significantly elevated levels in uremic patients. The method showed promising clinical utility for profiling serum constituents and for quantitative determination of a few important metabolites B Urinary estrogen levels are important for monitoring the normal pregnancy process as well as for the diagnosis of reproductive diseases.
Ji and co-workers described a micellar electrokinetic capillary chromatography MECC method for the determination of estrogens estrone, estradiol, estriol in urine samples. The solid-phase extraction was used for urine sample pretreatment. The analysis of two urine samples from week and week pregnant women showed that the method could provide adequate resolution and superior speed, but the sensitivity might limit its utility to the measurement of estriol and estrone B Sample was first collected and air-dried on a filter paper disk 0.
The paper was then dissolved in a buffer, and the resulting solution was filtered prior to the injection onto the capillary. A He-Cd laser with a wavelength of nm was used for excitation, and the fluorescence of the holo-RBP complex was monitored at nm by a photodiode. The comparison between the CE method and an established HPLC method showed good correlation from 28 serum, 19 dried venous blood, and 9 capillary dried blood spot samples.
This method was useful for screening vitamin A level, especially for children and premature newborns B Bory and co-workers developed a CE method for the determination of hypoxanthine and xanthine in urine.
The method was used in diagnosis of xanthinuria B Fragments of and base pairs bp in families carrying a difference of 7 CAG repeats or, in more difficult cases, fragments of and bp differing by only 1 CAG repeat were well resolved with precision and diagnostic value B The identification of cystic fibrosis transmembrane conductance regulator CFTR gene in led to the characterization of a wide variety of mutations in individuals affected by cystic fibrosis CF.
The remaining mutations, being quite rare or even unique with a higher incidence of particular mutations in limited geographical areas, were due to the founder effect. The protocol was based on CZE using liquid polymers as sieving media B They illustrated the resolution of two complementary single strands 95 bases of a DNA fragment. DNA fragments differing in size by only 1 base could be resolved, as shown for the and base fragments obtained from a heterozygote for insT CF mutation.
The following patterns are expected: for normal individuals, one peak or two peaks in a ratio.
In the case of trisomy 21, the following patterns are found: either three peaks in a ratio or a twopeak profile with a gene ratio. Gelfi and co-workers developed a CE method, offering precise diagnostic value by exploiting the intrinsic DNA absorbance at nm. The separation occurred in capillaries coated with a hydrophilic layer of poly[ N-acroyloylamino ethoxyethanol] and filled with a background electrolyte containing 89 mM Tris-borate, 2 mM EDTA, 2.
Their method offered high reproducibility, precise on-line quantitation, and automated data acquisition B In the late s, Chamberlain et al. Since each of them is based on the specific coamplification of nine dystrophin gene exons, a method attempting simultaneous analysis of DMD and BMD should offer unambiguous resolution and identification of 18 DNA fragments ranging in size from approximately to bp.
The method used a poly[ N-acroyloylamino ethoxyethanol]-coated capillary, a sieving polymer solution containing short-chain linear polyacrylamide average molecular weight of , and substitution of four fragments in the classical multiplex PCR reactions and bp in the Beggs method, and bp in the Chamberlain method with four new fragments of , , , and 88 bp. This method allowed the resolution and unambiguous identification of all 18 PCRamplified fragments in a single electrophoretic run.
The set of 18 fragments included the following: 88, , , , , , , , , , , , , , , , , and bp. Recently a point mutation GA in the coagulation factor V gene was shown to cause resistance for cleavage by activated protein C. The mutation is associated with an increased thrombotic risk and, thus far, the most common genetic cause of thrombophilia.
Current techniques to investigate the single base pair mutation at the DNA level employ an assay that is based on the PCR followed by restriction enzyme digestion or Southern blotting and allele-specific probing.
Van de Locht and co-workers described a method consisting of a single PCR in which two specially designed allele specific primers and two consensus primers were used in one reaction to distinguish between homozygous normal, heterozygous, and homozygous mutant individuals.
The amplification products were analyzed by CE with on-line UV detection. The method was automated and highly reproducible and could be used in a routine clinical setting B A bp fragment of hepatitis B virus DNA was successfully separated and quantified within 12 min. The method was applied to several patient samples, and the results were compared with those obtained from conventional electrophoresis and enzyme-linked immunosorbent assays B Felmlee and coworkers described a CE-based sizing method for the analysis of a reverse-transcribed PCR-amplified bp DNA fragment specifically for the hepatitis C viral genome.
All patients with primary infection showed concentrations in a range of 1. No signals were observed in seronegative donors. This procedure represented a practical alternative to other methods for quantification of HIV-1 RNA and might be useful in assessing the efficiency of antiretroviral agents, especially during the early stage when other conventional viral markers were often negative B Medium-chain acyl-coenzyme A dehydrogenase MCAD deficiency, which shows an autosomal recessive inheritance, is known to be highly prevalent among Caucasian population and often mimics as Reye-like syndrome or sudden infant death.
Arakawa and co-workers developed a method of capillary gel electrophoresis CGE with LIF detection to detect the most prevalent mutation lysineto-glutamic acid substitution in MCAD deficiency. A DNA fragment containing the mutation site was first amplified by PCR with two sets of allelespecific oligonucleotide primers and then followed by the CE analysis.
The method clearly distinguished these PCR products and facilitated the rapid diagnosis of the disease B The percentages of mutant and WT fragments were measured by CE, which showed that the percentages of mutant alleles in Calu-1, SK-LU-1, and A cell lines were 73, 84, and 72, respectively. The sensitivity of the original BstNI assay for K-ras codon 12 in conjunction with the analysis by CE was also tested using a series of titration experiments with one- and twostage amplification-BstNI digestion protocols.
CE was used to generate a calibration curve. The mutant allele was detected and the quantity was measured in the and dilutions in the one- and two-stage analyses. Four human lung adenocarcinomas were also analyzed. It was concluded that the method could be used for detection and quantitation of mutant K-ras alleles in premalignant lung lesions and exfoliated cells collected by cytologists from individuals at risk for lung cancer, as well as for follow-up of the progression of the mutant cell population during therapeutic intervention.
Felmlee and co-workers described the evaluation of CE-based singlestrand conformation polymorphism SSCP and dideoxy fingerprinting ddF analysis for the detection of single-point mutations within a M. The results demonstrated that the method might replace Southern blot hybridization B Sexing of human DNA in biological stains can be performed by amplifying a fragment of the X-Y homologous amelogenin gene.
The method was optimized with respect to the resolution and the analysis time and validated by comparing the results of XY sex typing with the results obtained from denaturing polyacrylamide gel electrophoresis with automated detection of the alleles using an ABI A automated sequencer. They studied the method for accurate determination of the number of short oligonucleotide units 2 or 16 bp for the VNTR and microsatellite repeat on the human genome, which might lead to a DNA diagnosis of cancer and heart disease B The CE provided an excellent resolution to two alleles differing by one or two 16bp repeat units in the DNA size range up to bp with high speed.
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The apoB alleles differing in length by two or four repeat units were readily distinguishable by CE in the DNA size range from to bp. It was believed that CE combining with PCR provided an excellent technique for accurate determination of the number of repeat units in apoB VNTR alleles and differentiation of heterozygous from homozygous individuals.
Drug Monitoring. Hyoetylaeinen and coworkers developed a MECC method for the fast screening and simultaneous determination of amphetamine, morphine, heroin acetomorphine , codeine methylmorphine , and caffeine in human serum and urine. Glycine buffer containing sodium dodecyl sulfate SDS pH All compounds were resolved in 18 min with a CV of spectrometry MS using precursor a neutral loss scans.
Two new in vitro metabolites, lysergic acid ethylamide LAE and 2-oxoLSD, were positively identified; their structures were established by comparing with reference standards. Several other possible metabolites detected were mono- and trioxylated metabolites of LSD. The major metabolic pathway of LSD by human liver microsomes was suggested to be deethylation. Perrett and Ross developed a MECC method for the rapid resolution and quantitation of antipyrine from endogenous compounds in saliva.
The separation was achieved within 1 min. The method used 50 mM sodium phosphate pH 9. Many other analgesics such as ketoprofen, daypo, and salicylates could also be determined by this method B In a separate study, Ashcroft and co-workers reported the use of CE in combination with MS for identification of a number of drugs and their metabolites in solid-phase extracts of human urine.
In urine obtained following the administration of ibuprofen, the drug itself, its glucuronide metabolite, the hydroxylated metabolite and its corresponding glucuronide, and the carboxylic acid metabolite as the glucuronide were all identified. Similarly, a range of metabolites of flurbiprofen and aspirin were also identified in urine extracts B Molteni and co-workers showed that methadone and its primary urinary metabolites, M1, could be easily detected by CZE using a borate buffer at pH 9.
Using an extraction procedure with disposable cartridges containing a copolymeric sorbent, the presence of methadone and M1 could be confirmed in all urines, whereas with direct urine injection, only two compounds could be detected in six urine samples.
Therefore, for unambiguous confirmation by CE, the extraction procedure was preferred. Compared with UV absorption detection, fluorescence detection showed a fold lower limit of detection for the selected compounds B Yu and co-workers developed a direct assay for cephalexin in human plasma by CZE.
The sample, untreated human plasma, was directly introduced into a capillary filled with a phosphate buffer at pH 9. Detection was carried out at nm. Bogan and co-workers developed a CE method with UV detection at nm for the rapid determination of free 7-hydroxycoumarin, the predominant metabolite of coumarin, in human urine and serum. The results were compared. The CE method had an analysis time of 1. There was no statistical difference between the results determined by either method B Deasy and coworkers applied the above method to study the metabolism of coumarin in human liver microsomes B Human liver microsomes from five patients were used, and the profiles clearly indicated that there was interindividual variability in coumarin 7-hydroxylase activity.
In a different study, Desiderio and Fanali used cyclodextrin-modified MECC to separate mephenytoin and its metabolite, 4-hydroxymephenytoin, in urine samples for chiral identification of different phenotypes in the oxidative metabolizing ability in man B Garcia and co-workers developed a rapid CE method for the quantitation of gabapentin in human serum.
The assay involved derivatization of gabapentin with fluorescamine to provide a chromophore for the fluorescence detection. The migration time of gabapentin was about 11 min.
No other therapeutic drugs or amino acids interfered with the gabapentin peak.
The CV was 2. The mean serum level for 52 patients on the drug was 5. Hempel and Blaschke reported a method for the enantioselective determination of zopiclone and its main metabolites in urine. Urine samples of two volunteers after oral administration of 7. With the same method, the zopiclone enantiomers were also quantified in saliva. Sodium valproate could also be determined by CZE. In the experiments, using standard AED compounds spiked in drugfree serum, linear correlations were observed between peak areas and serum AED concentrations over the ranges generally found in patient samples.
Taylor and Reid described a quantitative method for the determination of proguanil, chloroquine, and their metabolites by CZE.
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Results obtained using hydrodynamic and electrokinetic injection on the precision of measuring migration time and peak area were discussed and compared. The method incorporated with a solid-phase extraction procedure could be applied to the analysis of proguanil, chloroquine, and their metabolites in urine B Okun and co-workers determined an anticancer drug, prospidin, in human tissue after its derivatization with diethyldithiocarbamic acid sodium salt DDTC.
The study on the reaction between prospidin and DDTC revealed that a molar excess of the latter and 1. Sample preparation procedures included homogenization of freshly cut papilloma species and deproteinization by methanol.
Due to its speed and high resolution, CE was found to be well suited for monitoring drug therapy in clinical practice B Free amino acids and primary amines were labeled with fluorescein isothiocyanate prior to the analysis.
Electropherograms containing more than 50 peaks were obtained in less than 22 min. Twenty-one peaks were identified, and 19 were quantitated. This method was selective and sensitive for the determination of free amino acids and amines in biological samples B Sadecka and Polonsky investigated the separation and determination of amiloride, metoprolol, deacetylmetipranolol, labetalol, and furosemide in human serum and urine by capillary isotachophoresis CITP.
Endogenous and the possible exogenous compounds were almost totally removed from serum and urine by the solid-phase extraction using a Separon SGX C18 cartridge. The recovery of compounds varied from The CV varied from 0. The method had a detection limit of 0.
The extraction recovery R Analytical Chemistry, Vol. They also investigated the influence of various parameters on the chiral separation of oxprenolol and its primary metabolites, as well as the urinary excretion profiles of these compounds after orally administering a single dose of racemic oxprenolol B Coors and co-workers examined a CZE method for the quantification of diltiazem and desacetydiltiazem in plasma. Sample was prepared by liquid-liquid extraction.
Separation was accomplished by CE in 44 mM phosphate buffer at pH 2. No interferences from plasma were detected. The long-term reliability of the method was checked over a period of three months.
It was concluded that the method was a useful alternative to the already established HPLC method B Zong and Che developed a procedure for the quantitative analysis of strychnine and brucine, central nervous system stimulants, in the extracts of Strychnos nux-vomica seeds by CZE B The buffer solution used was 10 mM phosphate-methanol at pH 2.
This method was useful for the determination of strychnine and brucine in plant drug samples, as well as in human plasma. Zhang and co-workers established a CE method for the determination of theophylline and its metabolites. The method required a pretreatment of biological samples by solid-phase extraction.
It was rapid and could provide baseline resolution to all metabolites. The method was applied to the analysis of theophylline metabolism by the hepatic microsomes from rats treated with a variety of inducing agents for different forms of P enzymes that metabolize theophylline and to the analysis of human urine spiked with theophylline and its metabolites B The serum proteins were denatured by the addition of thrichloracetic acid.
The run buffer was phosphate containing mM SDS at pH 8, and the detection wavelength was nm. The linear calibration range was 5.
The method had an average recovery of Luksa and Josic reported the separation of cimetidine from its metabolites cimetidine amide, cimetidine sulfoxide , endogenous creatinine, and internal standard ranitidine in plasma by CE in less than 5 min. All compounds were well separated from cimetidine, including possible plasma ingredients, as the UV spectra of cimetidine standard and cimetidine from the plasma extract matched.
Soini and co-workers used two-component polymer mixtures of poly ethylene oxide -polydextran as the separation media for CE in the direct analysis of famotidine from untreated urine B They investigated the effects of the concentration of the individual polymers and their mixtures on the electroosmotic velocity and electrophoretic mobility of small pharmaceutical compounds. Separation efficiency was optimized in terms of the molecular masses of polymers, buffer concentrations, and percentages of organic solvents and cyclodextrins.
Hempel and Blaschke reported a method for the determination of zolpidem, a new sleep inducer belonging to the imidazopyridine class, and its main metabolites in untreated urine by CE with LIF detection B A nL sample of urine was directly applied to CE.
This procedure used no organic solvents. It was simple and fast. The separation was run in a 25 mM citrate buffer at pH 4. Chicharro and co-workers also developed a simple and rapid method for the simultaneous analysis of three sympathomimetic drugs ephedrine, pseudoephedrine, norephedrine in urine by CZE B A 50 mM phosphate buffer at pH The contents of these drugs could be directly determined from human urine.
This method might be used for doping control. In their procedure, barbiturates were extracted from various biological fluids at pH 4. The detection was done by monitoring UV absorption at nm.Many studies qualitatively or quantitatively examined the affinity of antibodies by such techniques as enzyme-linked immunosorbent assays AA67 , surface plasmon resonance AA73 , quartz crystal microbalances A72 , scanning probe microscopy A73 , affinity sensors A74 , light-addressable potentiometric sensors A75 , optical grating coupler sensors A76 , affinity capillary electrophoresis A77 , and titration calorimetry A Sample preparation procedures included homogenization of freshly cut papilloma species and deproteinization by methanol.
This procedure represented a practical alternative to other methods for quantification of HIV-1 RNA and might be useful in assessing the efficiency of antiretroviral agents, especially during the early stage when other conventional viral markers were often negative B The NISTmAb is a publicly available research tool intended to facilitate advancement of biopharmaceutical analytics.
These two complexes were resolved completely by CE and detected quantitatively at nm. In one such study Matsunaga et al. Recent developments in the area of electrochemiluminescence were discussed by Hoyle et al.