Evaluation of a new valproic acid enzyme immunoassay and comparison with a capillary gas-chromatographic method.

1981 ◽  
Vol 27 (1) ◽  
pp. 169-172 ◽  
Author(s):  
S L Braun ◽  
A Tausch ◽  
W Vogt ◽  
K Jacob ◽  
M Knedel
Keyword(s):  
Valproic Acid ◽  
Enzyme Immunoassay ◽  
Chromatographic Method ◽  
Comparison Method ◽  
Manual Method ◽  
Analytical Recovery ◽  
Significant Difference ◽  
High Concentrations ◽  
Assay Precision ◽  
Gas Chromatographic Method

Abstract A new homogeneous immunoassay (EMIT) for valproic acid was evaluated. Besides testing the manual version of this enzyme immunoassay, we also developed two mechanized procedures for centrifugal analyzers (the CentrifiChem and the COBAS system), which take less time and are more precise than the manual method. Within-assay precision (CV) was 4.5% with the manual technique and 2% with the analyzers. Between-assay precision (CV) ranged from 4 to 13% for all three techniques. Accuracy of th manual method was checked by dilution and analytical recovery experiments. Our comparison of the EMIT results with those obtained by a comparison method (capillary gas chromatography) showed no significant difference. No interference from hemolysis, hyperbilirubinemia, or aliphatic amino acids was observed. At high concentrations of bile acids and with lipemic sera the analytical recovery rates decreased slightly, to 87% and 92%, respectively.

scholarly journals Investigation of pesticide residues in surface water in some areas of agricultural production at Ho Chi Minh city

2013 ◽  
Vol 16 (3) ◽  
pp. 106-119
Author(s):  
Phu Ly Sy Nguyen ◽  
Nguyen Duc Do ◽  
Hien Thi To
Keyword(s):  
Surface Water ◽  
Pesticide Residues ◽  
Agricultural Production ◽  
Chromatographic Method ◽  
Organophosphorus Pesticides ◽  
Ho Chi Minh City ◽  
Growth Stages ◽  
High Concentrations ◽  
Gas Chromatographic Method ◽  
Agricultural Areas

Residual levels of organochlorine and organophosphorus pesticides in surface water in some agricultural areas at Ho Chi Minh City were investigated in 2012. Four organophosphorus pesticides including Malathion, Parathion, Ethion and Trithion and seven organochlorine pesticides including Alpha - HCH, beta-HCH, gammaHCH, aldrin, Heptachlor – epoxide, AlphaEndosulfan and Endosulfan-sulfate were determined in the surface water in four dicstricts : Binh Chanh, Hoc Mon, Cu Chi and Binh Tan using gas chromatographic method with electron capture detector (GCECD). The results showed that residues of pesticide were found with high concentrations in surface water in agricultural areas and pesticide residues changed depending on growth stages of crops. The concentration and distribution of pesticides were different in the water samples at different sites. Residues of pesticides such as Parathion, Ethion and Trithion were detected in surface water although these chemicals had been banned.

Homogeneous enzyme immunoassay for tobramycin evaluated and compared with a radioimmunoassay.

1982 ◽  
Vol 28 (6) ◽  
pp. 1370-1374 ◽  
Author(s):  
J Woo ◽  
M A Longley ◽  
D C Cannon
Keyword(s):  
Enzyme Immunoassay ◽  
Room Temperature ◽  
Correlation Study ◽  
Stability Study ◽  
Data Handling ◽  
Handling System ◽  
Analytical Recovery ◽  
Assay Precision ◽  
Absorbance Data ◽  
Homogeneous Enzyme Immunoassay

Abstract We evaluated a commercially available homogeneous enzyme immunoassay (EMIT, Syva Co.) for tobramycin against a reference radioimmunoassay (RIA) method. Between-assay precision (CV) was 2.9% at 6.2 mg/L and 3.0% for values in the range of 1.0-7.6 mg/L. Accuracy based on a recovery experiment (1.0-13.0 mg/L) yielded an analytical recovery of 88-112%. A correlation study with 75 sera from patients on tobramycin therapy showed that EMIT = 0.984 RIA - 0.0808, r = 0.993. Neither the EMIT nor the RIA procedure was affected by the presence of gentamicin, amikacin, and vancomycin. Absorbance data from the EMIT system calculated with the conventional RIA logit-log algorithm correlate well with results generated by the Syva data-handling system (logit-log = 1.077 Syva - 0.318, r = 0.998). A reagent stability study indicated that the EMIT reagents, once reconstituted, remain stable for at least 17 days when stored at refrigerated temperatures, or 11 days if stored at room temperature, thus enabling frequent "stat" assays without the need to prepare a calibration curve each time.

Homogeneous enzyme immunoassay for cortisol with a centrifugal analyzer.

1984 ◽  
Vol 30 (11) ◽  
pp. 1824-1826 ◽  
Author(s):  
J M Izquierdo ◽  
A Quirós ◽  
J Alvarez-Uría ◽  
P Sotorrío
Keyword(s):  
Enzyme Immunoassay ◽  
Protein Complex ◽  
Acidic Solution ◽  
Serum Cortisol ◽  
Standard Curve ◽  
Analytical Recovery ◽  
Target Values ◽  
Assay Precision ◽  
Homogeneous Enzyme Immunoassay ◽  
Control Samples

Abstract We determine serum cortisol by a homogeneous enzyme immunoassay in the Cobas Bio centrifugal analyzer. To unbind cortisol from its protein complex, serum is treated for 15 min with an acidic solution. The reaction then proceeds automatically in the analyzer at 37 degrees C. To 50 microL of sample mixture is added 125 microL of reagent (cortisol antibodies, glucose 6-phosphate, and NAD+). This mixture is incubated for 60 s, after which 25 microL of a cortisol derivative labeled with glucose 6-phosphate is added; the increase in absorbance is monitored at 340 nm. The standard curve was linear from 10 to 500 micrograms of cortisol per liter. Within-assay precision (CV) varied from 0.2 to 0.6%, between-assay precision from 6.2 to 10.6%. Analytical recovery ranged from 100 to 103%. Results for control samples deviated from target values by 1.4 to 7.8%. Results compared well with those by radioimmunoassay. The method is reliable and practicable and will usefully replace previous routine methods for serum cortisol.

Gas Chromatographic Method for the Determination of Valproic Acid in Human Plasma

1979 ◽  
Vol 1 (2) ◽  
pp. 217-242 ◽  
Author(s):  
Anne E. Hershey ◽  
Jeffrey R. Patton ◽  
Kenneth H. Dudley
Keyword(s):  
Valproic Acid ◽  
Human Plasma ◽  
Chromatographic Method ◽  
Gas Chromatographic Method

Avidin-Biotin Enzyme Immunoassay of Osteocalcin in Serum or Plasma

1992 ◽  
Vol 38 (10) ◽  
pp. 1968-1974 ◽  
Author(s):  
J Jaouhari ◽  
F Schiele ◽  
S Dragacci ◽  
P Tarallo ◽  
J P Siest ◽  
...  
Keyword(s):  
Human Serum ◽  
Enzyme Immunoassay ◽  
Healthy Subjects ◽  
Limit Of Detection ◽  
Serum Concentrations ◽  
Calcium Dependent ◽  
Standard Curve ◽  
Microtiter Plates ◽  
Analytical Recovery ◽  
High Concentrations

Abstract We describe a competitive enzyme immunoassay, the ExtrAvidin-biotin system, for determining osteocalcin in human serum or plasma. Antibodies were raised against bovine osteocalcin. Binding of the antibodies to osteocalcin was calcium-dependent. Limit of detection is 0.07 nmol/L (0.4 microgram/L). The standard curve for method is linear between 0.3 and 17.6 nmol/L (1.9 and 100 micrograms/L). Interassay CV over the range 0.9 to 14.8 nmol/L (5.3 to 84 micrograms/L) is 7.5% to 11.7%. Analytical recovery is 105% +/- 5% (mean +/- SD). The measurement, which is adapted to microtiter plates, requires only 20 microL of serum and 5 h. The coefficient of correlation between the concentrations measured by this method and by a commercially available radioimmunoassay kit (CIS Biointernational) is 0.91. Osteocalcin can be measured in serum or heparinized plasma. Hemolysis (174 mumol/L hemoglobin) reduces osteocalcin concentration by 54%. High concentrations of triglycerides (7 mmol/L) give an overestimation of 63%. Serum concentrations of osteocalcin measured in 130 healthy subjects (ages 15-64 years) and 86 children (ages 4-14 years) were 1.4 +/- 0.8 and 4.0 +/- 1.5 nmol/L (8.1 +/- 4.6 and 22.5 +/- 8.6 micrograms/L), respectively (mean +/- SD).

Rapid gas-chromatographic assay of lactulose and mannitol for estimating intestinal permeability

1995 ◽  
Vol 41 (5) ◽  
pp. 752-756 ◽  
Author(s):  
M Celli ◽  
P D'Eufemia ◽  
R Dommarco ◽  
R Finocchiaro ◽  
D Aprigliano ◽  
...  
Keyword(s):  
Intestinal Permeability ◽  
Chromatographic Method ◽  
High Recovery ◽  
Normal Children ◽  
Multiple Peaks ◽  
Analytical Recovery ◽  
Gluten Sensitive Enteropathy ◽  
The Mean ◽  
Gas Chromatographic Method

Abstract We developed a gas-chromatographic method to determine urinary mannitol and lactulose. The procedure for purification of urine by a resin was optimized for purification of analytes and high recovery; the aliquot of resin chosen (500 mg) was kept in contact with the urine for 1 min. The recoveries of mannitol and lactulose were > 85% at concentrations that include both normal and pathological values. Sugars were converted to oximes before the silylation step to avoid multiple peaks for the anomeric forms. The calibration was linear over the range 0.1-1 microgram of sugar injected. Analytical recovery of the sugars ranged from 90% to 95.3% for mannitol and from 90.4% to 95.8% for lactulose. The mean within-day imprecision (CV) was 6.2% for mannitol and 4.7% for lactulose; the between-day CV was 6.7% for mannitol and 5.1% for lactulose. A lactulose/mannitol ratio of 0.035 completely differentiated 28 normal children and 28 children with active gluten-sensitive enteropathy, whose mean ratios were 0.022 (SD 0.007) and 0.084 (SD 0.054), respectively.

Urinary 3-methoxy-4-hydroxyphenylacetic (homovanillic) and 3-methoxy-4-hydroxymandelic (vanillylmandelic) acids: gas-liquid chromatographic methods and experience with 13 cases of neuroblastoma.

1977 ◽  
Vol 23 (12) ◽  
pp. 2247-2249 ◽  
Author(s):  
M A Brewster ◽  
D H Berry ◽  
M Moriarty
Keyword(s):  
Homovanillic Acid ◽  
Chromatographic Method ◽  
Internal Standard ◽  
Silyl Ether ◽  
Vanillylmandelic Acid ◽  
Ether Extraction ◽  
Analytical Recovery ◽  
Hydroxyphenylacetic Acid ◽  
Gas Chromatographic Method ◽  
Liquid Chromatographic

Abstract We present a quantitative gas-chromatographic method for determining urinary 3-methoxy-4-hydroxymandelic acid (vanillylmandelic acid) and 3-methoxy-4-hydroxyphenylacetic acid (homovanillic acid). In this rapid technique an internal standard is used and the procedure involves ether extraction and silyl ether formation. Analytical recovery of vanillylmandelic acid averages 87.5% (CV, 0.95%), of homovanillic acid 102.3% (CV, 9.95%). Our data on 34 samples from 13 neuroblastoma patients show that homovanillic acid is more consistently elevated than is vanillylmandelic acid.

scholarly journals A Survey on the Methanol Content of Home Distilled Alcoholic Beverages in Transylvania (Romania)

2013 ◽  
Vol 59 (4) ◽  
pp. 206-208 ◽  
Author(s):  
Croitoru Md ◽  
Topor Elena ◽  
Fülöp Ibolya ◽  
Fogarasi Erzsébet
Keyword(s):  
Chromatographic Method ◽  
Methanol Concentration ◽  
Alcoholic Beverages ◽  
Methanol Content ◽  
Alcoholic Drinks ◽  
High Concentrations ◽  
Gas Chromatographic Method ◽  
Plum Brandy ◽  
Chronic Use ◽  
Made In

Abstract Objective: Methanol appears in relatively high concentrations in alcoholic beverages obtained from fermented fruits distillates. These products are traditionally home made in many regions in Romania and other EU countries. The chronic use of products with high methanol concentration can be considered a health risk. The purpose of this work was to measure methanol concentration in a Romanian region where brandy-type alcoholic products are made from different fruits (plum, apple, pear, grapes), and to observe if there is a type of product that contains more methanol than the others. Methods: The content of methanol in the tested alcoholic beverages was determined using a gas chromatographic method. Results: Only 18% of the tested 56 samples met UE regulation regarding methanol content of alcoholic beverages (0.4% in alcoholic drinks containing 40% ethanol). The highest concentration of 2.39% was found in a plum brandy. Plum brandies contained significantly higher amounts of methanol than brandies made from other fruits (0.91 vs 0.52%, p = 0.01). Conclusions: Home distilled alcoholic beverages obtained from fruits are a health threat due to their high methanol content. Strict regulations and tests should be introduced for such products

scholarly journals Development and validation of a gas chromatographic method for the assay of memantine hydrochloride in pure and tablet dosage forms

2011 ◽  
Vol 9 (1) ◽  
pp. 1-8 ◽  
Author(s):  
K. Siddappa ◽  
Metre Mallikarjun ◽  
Tambe Mahesh ◽  
Kote Mallikarjun ◽  
Reddy Chandrakanth
Keyword(s):  
Chromatographic Method ◽  
Internal Standard ◽  
Pharmaceutical Preparations ◽  
Reference Method ◽  
Pharmaceutical Formulations ◽  
Fused Silica ◽  
Column Temperature ◽  
Significant Difference ◽  
Gas Chromatographic Method

A gas chromatographic method has been developed and validated for the determination of memantine hydrochloride (MMT) in pure and pharmaceutical preparations. The detection was carried out using flame ionization detector. Separation was achieved on a DB-624 fused silica packed capillary column (30 m x 0.320 mm x 1.8 ?m). Nitrogen was used as a carrier gas at a flow rate of 40 mL/min. The column temperature was maintained at 300?C while the temperature of injection port and detector were maintained at 270? and 300?C, respectively. Gabapentin (GPN) was used as an internal standard. The procedure gave a linear response over the concentration range of 0.5-3.5 mg/mL with sufficient reproducibility. The method has been applied successfully for the determination of MMT in pure and pharmaceutical formulations. The excipients present in the formulations did not interfere with the assay procedure. The recovery values were found to be in the range of 99.85-100.1% with RSD values less than 1%. The results obtained from this method were compared with the reference method (HPTLC) reported in literature and no significant difference was found statistically.

Microbiological assay for vitamin B12 with use of a colistin-sulfate-resistant organism.

1987 ◽  
Vol 33 (1) ◽  
pp. 52-54 ◽  
Author(s):  
B P Kelleher ◽  
K G Walshe ◽  
J M Scott ◽  
S D O'Broin
Keyword(s):  
Vitamin B12 ◽  
Serum Vitamin ◽  
Assay System ◽  
Microbiological Assay ◽  
Resistant Organism ◽  
Colistin Sulfate ◽  
Assay Performance ◽  
Analytical Recovery ◽  
High Concentrations ◽  
Assay Precision

Abstract In this simplified microbiological assay for serum vitamin B12, Lactobacillus leichmanii (NCIB 8117) adapted to tolerate high concentrations (500 mg/L) of the polymyxin antibiotic colistin sulfate is used. Results were similar in parallel experiments in which we used both the parent strain of L. leichmanii (NCIB 8117), and the new adapted strain. Evaluation of assay performance showed excellent analytical recovery of added cyanocobalamin (97%, SD 3%) and good interassay and intra-assay precision (CV less than 5%). This modified assay system obviates the need to sterilize culture medium and glassware. Consequently, assay manipulations may be carried out openly, without aseptic precautions. Moreover, this adapted organism would be suitable for use in an automated microbiological assay system.

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