Novel reagent and method for direct determination of chloride in serum with a centrifugal analyzer.

1980 ◽  
Vol 26 (13) ◽  
pp. 1874-1877 ◽  
Author(s):  
W T Law ◽  
G Ertingshausen
Keyword(s):  
Serum Protein ◽  
Acid Concentration ◽  
Perchloric Acid ◽  
Direct Determination ◽  
Standard Curve ◽  
Brij 35 ◽  
Short Analysis Time ◽  
Lauryl Ether ◽  
Ferric Perchlorate

Abstract We report a novel reagent containing ferric perchlorate, perchloric acid, and polyoxyethylene (23) lauryl ether (Brij 35) with which the concentration of chloride in serum can be measured. We applied this reagent to use with a centrifugal analyzer (CentrifiChem 400) in a dynamic bichromatic procedure, resulting in broad linearity of the standard curve (0-180 mmol/L), short analysis time (1 min), and little interference from bilirubin, hemoglobin, turbidity, or bromide ions. The reagent is simple, contains no mercury, and the combination of low acid concentration and surfactant prevents serum protein precipitation. Precision is good (for x- = 93 mmol/L, CV = 1.55%), and results correlate well with those obtained by coulometry (r = 0.974).

A direct determination of taurine in perchloric acid-deproteinized biological samples

1987 ◽  
Vol 163 (2) ◽  
pp. 339-342 ◽  
Author(s):  
Tomihiro Hirai ◽  
Hideo Ohyama ◽  
Ryo Kido
Keyword(s):  
Perchloric Acid ◽  
Biological Samples ◽  
Direct Determination

Collaborative Study of Ion Selective Electrode Method for the Direct Determination of Fluoride in Feeds

1975 ◽  
Vol 58 (3) ◽  
pp. 477-481 ◽  
Author(s):  
Laszlo Torma
Keyword(s):  
Standard Deviation ◽  
Collaborative Study ◽  
Direct Determination ◽  
Ion Selective Electrode ◽  
Official Method ◽  
Selective Electrode ◽  
Standard Curve ◽  
Electrode Method ◽  
Aoac Method

Abstract A rapid and precise method for the determination of fluoride in feeds employs HC1 extraction of the sample. Acetate buffer and sodium citrate are added to control pH and ionic strength. The amount of fluoride is calculated from a standard curve after measuring the potentials of standard and sample solutions. Eight collaborators participated in the study of the method. Statistical values on 3 pairs of samples were calculated. The standard deviation, precision, coefficient of variation, and bias, respectively, were: Pair 1, 0.005071, 0.001763, 3.09, 0.0034; Pair 2, 0.037122, 0.006475, 1.82, 0.0258; Pair 3, 0.034587, 0.013021, 2.63, 0.0227. The results from the proposed method agreed favorably with the values obtained by using the official final action AOAC method, 7.089. The average and standard deviation, respectively, for individual samples by the proposed method were: Sample 3, 0.049, 0.0029; Sample 4, 0.059, 0.0021; Sample 5, 0.334, 0.0114; Sample 6, 0.341, 0.0101; Sample 7, 0.511, 0.0219; Sample 8, 0.492, 0.0237. By the official method the values were: Sample 3, 0.049, 0.0041; Sample 4, 0.058, 0.0029; Sample 5, 0.334, 0.0055; Sample 6, 0.331, 0.0082; Sample 7, 0.517, 0.0183; Sample 8, 0.499, 0.0175. The ion selective electrode method has been adopted as official first action.

Polarographic Determination of Selenium in Biological Materials

1965 ◽  
Vol 48 (5) ◽  
pp. 877-884
Author(s):  
Gary D Christian ◽  
Edward C Knoblock ◽  
William C Purdy
Keyword(s):  
Perchloric Acid ◽  
Direct Determination ◽  
Biological Materials ◽  
Acid Digestion ◽  
Organoselenium Compounds ◽  
Millipore Filter ◽  
Digestion Mixture ◽  
Wet Weight ◽  
Ethylene Chloride

Abstract Polarography has been applied to the determination of selenium in biological materials. The direct determination described requires as little as 30 minutes for a single analysis. To increase the sensitivity, the selenium is isolated by one of two methods: The element is isolated by filtering through a Millipore filter, digesting the filter plus selenium, and obtaining a polarogram; or the selenium-diaminobenzidine complex is formed directly in the acid digest and then is extracted into a mixture of chloroform and ethylene chloride, the complex is backextracted into 2M perchloric acid, and a polarogram is obtained. Polarographic revalues are reported for the two selenium-DAB waves. As little as 0.2 µg selenium can be determined in a 1–2 g wet weight sample. Recoveries of organoselenium compounds from two different acid-digestion mixtures were comparable. A modification of the digestion mixture described by Cummins, et al. is given. Most procedures described require 2 hours or less analysis time for a single sample.

scholarly journals Enzyme Immunoassay for Direct Determination of Microcystins in Environmental Water

1997 ◽  
Vol 80 (2) ◽  
pp. 408-417 ◽  
Author(s):  
Satoshi Nagata ◽  
Tomoaki Tsutsumi ◽  
Akihiro Hasegawa ◽  
Fuyuko Yoshida ◽  
Yoshio Ueno ◽  
...  
Keyword(s):  
Tap Water ◽  
Direct Determination ◽  
Environmental Water ◽  
Cross Reactivity ◽  
Enzyme Linked Immunosorbent Assay ◽  
Powerful Method ◽  
Standard Curve ◽  
Liquid Chromatographic ◽  
Reliable Correlation

Abstract An enzyme-linked immunosorbent assay (ELISA) was developed for direct quantitation of microcys- tins (MCs), a group of freshwater cyanobacterial toxins. An anti-MC monoclonal antibody exhibiting broad cross-reactivity to major MC derivatives was used. The detection limit and linear range of the ELISA standard curve with microcystin-(leucine-ar-ginine) (MCLR), a variant of MCs, were 20 and 20–500 pg/mL, respectively. For analysis of MC released from cyanobacterial cells, water sample filtered through a glass fiber filter was applied directly to ELISA. For analysis of total MC (released MC plus intracellular MC), intracellular toxin was extracted by freeze-thawing twice before filtration. Mean recovery of MCLR added to tap water and toxin-free environmental water was 101%, with a coefficient of variation (CV) of 7.3% at toxin levels of 20–500 pg/mL. Mean recovery of MCLR added to toxin-free cyanobacterial extracts was 93%, with a CV of 12.5% at toxin levels of 50–500 pg/mL. At 20 pg/mL, an increasing matrix effect on assay variance was observed; therefore, both released MC and total MC were measured in the range 50–500 pg/ mL. Comparative studies with a liquid chromatographic (LC) method showed that the ELISA gives a reliable correlation with LC for analysis of MC in water extracts of natural blooms and cultured cyanobacterial cells (r = 0.98). The ELISA was applied to water samples collected from lakes and ponds in Japan. In 4 of 13 and 12 of 17 samples, 81–800 pg released MC/mL and 64–94 000 pg total MC/mL were detected, respectively. By LC separation followed by the ELISA analysis, the presence of MCLR, microcystin-arginine-arginine, and micro-cystin-tyrosine-arginine were confirmed in 4 ELISA-positive samples selected randomly. The newly developed ELISA is a reliable and powerful method for mass monitoring of MC levels in environmental water.

scholarly journals Rapid HPLC Determination of Pioglitazone in Human Plasma by Protein Precipitation and Its Application to Pharmacokinetic Studies

2010 ◽  
Vol 93 (3) ◽  
pp. 876-881 ◽  
Author(s):  
Ziba Islambulchilar ◽  
Hadi Valizadeh ◽  
Parvin Zakeri-Milani
Keyword(s):  
Human Plasma ◽  
Perchloric Acid ◽  
Bioequivalence Study ◽  
Hplc Method ◽  
Protein Precipitation ◽  
Pharmacokinetic Studies ◽  
Uv Detector ◽  
High Reproducibility ◽  
Standard Curve

Abstract A simple and rapid HPLC method with UV detection was developed for the determination of pioglitazone in human plasma. The method was based on protein precipitation using perchloric acid on an ODS column. The mobile phase consisted of a mixture of phosphate buffer, methanol, acetonitrile, and 12 M perchloric acid (54 + 33 + 12 + 1, v/v/v/v). The UV detector was set at 269 nm. Under these conditions, the retention time of pioglitazone was 5.2 min. The standard curve was linear over the range of 502000 ng/mL pioglitazone in human plasma. The within-day and between-day precision studies showed high reproducibility, with CV less than 5. The LOQ was 44.2 ng/mL. The method has been applied to a bioequivalence study after administration of pioglitazone as 30 mg tablets to 12 healthy volunteers.

Use of the Du Pont "Automatic Clinical Analyzer" in Direct Determination of Lactic Acid in Plasma Stabilized with Sodium Fluoride

1972 ◽  
Vol 18 (11) ◽  
pp. 1334-1338 ◽  
Author(s):  
James O Westgard ◽  
Brenda L Lahmeyer ◽  
Marvin L Birnbaum
Keyword(s):  
Lactic Acid ◽  
Sodium Fluoride ◽  
Perchloric Acid ◽  
Standard Error ◽  
Direct Determination ◽  
Plasma Lactate ◽  
Potassium Oxalate ◽  
Standard Deviations ◽  
Stable Plasma

Abstract We have studied the determination of lactic acid with the Du Pont ACA and the suitability of plasma as a sample. Blood collected in sodium fluoride/ potassium oxalate Vacutainers and separated in 15 min provided acceptably stable plasma. With a 40-µl sample of plasma, results are linearly related to concentration to 20 mmol/ liter. Standard deviations were 0.16-0.22 mmol/ liter for day-to-day precision. When lactate was added to 53 samples, an average of 99.11% was recovered analytically. Results for plasma lactate (y-axis) agreed with those on plasma filtrates by the Calbiochem "Rapid Lactate" method (n, 92; slope, 1.025; y intercept, -0.086 mmol/liter; standard error, 0.23 mmol/liter). Perchloric acid filtrates can also be analyzed, but fluoride-stabilized plasma is simpler to use.

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