Fluorometric determination of magnesium in serum with 2-hydroxy-1-naphthaldehyde salicyloylhydrazone.

1989 ◽  
Vol 35 (7) ◽  
pp. 1492-1496 ◽  
Author(s):  
P C Ioannou ◽  
D G Konstantianos
Keyword(s):  
Regression Analysis ◽  
Intensive Care ◽  
Linear Regression Analysis ◽  
Colorimetric Method ◽  
Fluorometric Method ◽  
Fluorometric Determination ◽  
Serum Samples ◽  
Standard Curve ◽  
Relative Standard

Abstract This simple, rapid, sensitive fluorometric method for determining magnesium is based on formation of a fluorescent complex of magnesium with 2-hydroxy-1-naphthaldehyde salicyloyl-hydrazone in alkaline ethanolic medium (lambda ex = 420 nm, lambda em = 460 nm). The detection limit of the method is 0.05 microgram/L (2 nmol/L) and the relative standard deviations (CVs) are 0.8%, 1.1%, and 2.5% at magnesium concentrations of 50, 5.0, and 0.50 microgram/L, respectively. The standard curve is linear from 0 to 250 micrograms/L (0-10 mumol/L). We investigated the chemistry of the reaction, and have applied the method to determine magnesium in 100-fold-diluted, otherwise untreated serum samples. Within-run CVs for the method were 1.7%, 1.1%, and 1.3% at mean magnesium concentrations of 15.7, 26.4, and 36.2 mg/L, respectively. Day-to-day CVs were 2.7%, and 3.6% at mean magnesium concentrations of 10.1 and 25.5 mg/L, respectively. Samples from 96 hospitalized patients in intensive-care units were analyzed by the proposed method (y) and by an automated colorimetric method involving Magon sulfonate reagent (x). Linear regression analysis of the results yielded: y = 1.01x - 0.04 (r = 0.982, Sxy = 0.90).

Rapid Fluorometric Determination of Benzo(a)pyrene in Foods

1982 ◽  
Vol 45 (2) ◽  
pp. 139-142 ◽  
Author(s):  
YASUHIDE TONOGAI ◽  
SHUNJIRO OGAWA ◽  
MASATAKE TOYODA ◽  
YOSHIO ITO ◽  
MASAHIRO IWAIDA
Keyword(s):  
Detection Limit ◽  
Peak Height ◽  
Excitation Wavelength ◽  
Activated Alumina ◽  
Fluorometric Method ◽  
Fluorometric Determination ◽  
Standard Curve ◽  
Layer Chromatography ◽  
Entire Procedure

A simple and rapid fluorometric method for determining benzo (a) pyrene in foods was developed. Benzo (a) pyrene is extracted from foods with n-hexane:ether mixture (4:1), purified through a column of activated alumina and determined fluorometrically. An excitation wavelength of 295 nm and emission wavelength of 403 nm were used for calculating concentrations of benzo (a) pyrene. The peak height at 403 nm and baseline between 392 and 418 nm were employed to derive a standard curve for quantitating benzo (a) pyrene. A calibration curve for between 0.04 – 4 ng/ml of benzo (a) pyrene was used. Recoveries of benzo (a) pyrene from 14 kinds of food spiked at levels of 20 and 2ppb were within the range of 79.5 – 93.8% and 50.0 – 80.6%, respectively. The entire procedure takes only one hour with the detection limit being 0.1 ppb. Benzo (a) pyrene detected was reconfirmed by thin-layer chromatography.

Fluorometric Determination of Selenium in Foods

1974 ◽  
Vol 57 (2) ◽  
pp. 368-372 ◽  
Author(s):  
Milan Ihnat
Keyword(s):  
Standard Deviation ◽  
Milk Powder ◽  
Skim Milk ◽  
Skim Milk Powder ◽  
Food Samples ◽  
Fluorometric Method ◽  
Fluorometric Determination ◽  
Relative Standard ◽  
The Mean

Abstract A fluorometric method using 2,3-diaminonaphthalene for estimating selenium has been evaluated with regard to its applicability to food samples. Charring of the sample during digestion appeared to result in losses of native and added selenium from some samples, so a modified wet digestion procedure was introduced. Digestion first in nitric acid followed by a mixture of nitric-perchloric-sulfuric acids substantially reduced the incidence of sample charring for a variety of foods. The mean apparent recovery of selenium added as selenite or selenate at 100 and 500 ng levels to 0.1 and 1.0 g corn cereal, skim milk powder, and meat and 0.1 g fish was 101.0%; the actual recovery of the same levels of selenium from standard solutions was 96.6%. For a variety of samples containing 5—750 ng native or added selenium, the standard deviation as 4.7 + 1.95 X 10-2W ng, where W = ng selenium in the sample taken for analysis. The relative standard deviation (RSD) as a function of selenium weight (ng) was 50% (10), 6.7% (100), 4.3% (200), 3.1% (400), 2.7% (600), and 2.5% (800). The detection limit (weight of selenium at which RSD = 50%) was 10 ng at a mean blank level of 25 ng.

Fluorometric Determination of Histamine in Tuna: Collaborative Study

1977 ◽  
Vol 60 (5) ◽  
pp. 1131-1136 ◽  
Author(s):  
Walter F Staruszkiewicz
Keyword(s):  
Collaborative Study ◽  
Colorimetric Method ◽  
Fluorometric Method ◽  
Fluorometric Determination ◽  
Canned Tuna

Abstract Six samples of canned tuna, albacore, yellow-fin, and skipjack, in water or oil pack were analyzed in duplicate by a fluorometric method and the AOAC colorimetric method. For the fluorometric method, recoveries of histamine added to acceptable tuna averaged 99% with a range of 91 to 107%. Agreement between laboratories for the analyses of decomposed tuna containing 20–200 mg histamine/100 g sample was excellent. Results from the fluorometric method are comparable with those from the AOAC colorimetric method ; the fluorometric method has been adopted as official first action.

scholarly journals Fluorometric Determination of δ-Aminolaevulinate Dehydratase Activity in Human Erythrocytes as an Index to Lead Exposure

1975 ◽  
Vol 21 (12) ◽  
pp. 1783-1787 ◽  
Author(s):  
Saroj K Chakrabarti ◽  
Jules Brodeur ◽  
Robert Tardif
Keyword(s):  
Negative Correlation ◽  
Lead Exposure ◽  
Acidic Medium ◽  
Present Method ◽  
Colorimetric Method ◽  
Human Erythrocytes ◽  
Fluorometric Method ◽  
Fluorometric Determination ◽  
Dehydratase Activity

Abstract We describe a fluorometric method for determining δ-aminolaevulinate dehydratase (EC 4.2.1.24) activity in human erythrocytes and compare it with the existing colorimetric method. Incubation conditions are identical. In the proposed method, the porphobilinogen formed during incubation is converted to a stable and highly fluorescent uroporphyrin by heating for 20 min at 93 °C in an acidic medium in the presence of air. The correlation between results by the two methods was good (r = 0.89). We found a good negative correlation between the activity of the enzyme and the concentration of circulating lead with both methods (r = -0.61 for present method and -0.59 for colorimetric method) for groups of persons subjected to various degrees of lead exposure. Our method is more sensitive and accurate, requires less sample, and the fluorescence is more stable than is the color in the colorimetric method.

Kinetic fluorometric determination of aluminum in serum.

1986 ◽  
Vol 32 (8) ◽  
pp. 1481-1483 ◽  
Author(s):  
P C Ioannou ◽  
E A Piperaki
Keyword(s):  
Atomic Absorption ◽  
Metal Chelate ◽  
Linear Regression Analysis ◽  
Spectrometric Method ◽  
Serum Samples ◽  
Standard Curve ◽  
Aluminum Ions ◽  
Standard Additions ◽  
Atomic Absorption Spectrometric

Abstract We describe a simple fluorometric method for determining aluminum in serum samples by monitoring the rate of reaction of 2-hydroxy-1-naphthaldehyde-p-methoxybenzoylhydrazone with aluminum ions. The emission of the resulting fluorescent metal-chelate formed is measured at 475 nm. Aluminum was measured in the supernate of serum after proteins were removed by precipitation with concentrated nitric acid, and calculations were based on the technique of standard additions. Within-run precision (CV) was 7.8% and 4.8% at mean aluminum concentrations of 7.7 and 60.7 micrograms/L, respectively (n = 10); between-run precision (CV) was 8.9% and 5.7% at mean aluminum concentrations of 23.3 and 46.8 micrograms/L, respectively (n = 10). The standard curve for the method is linear over the range of 0-250 micrograms of aluminum per liter. Samples from 49 patients were analyzed for aluminum by the proposed method (y) and by electrothermal atomic absorption spectroscopy (x). Linear regression analysis of the results yielded the equation y = 0.98x + 2.3 (r = 0.989, Syx = 6.7). The proposed method is comparable in sensitivity to the well-accepted atomic absorption spectrometric method but is simpler and less expensive.

scholarly journals A simple method for determination of deoxynivalenol in cereals and flours

2011 ◽  
Vol 20 (No. 2) ◽  
pp. 63-68 ◽  
Author(s):  
F. Kotal ◽  
Z. Radová
Keyword(s):  
Regression Analysis ◽  
Standard Deviation ◽  
Limit Of Detection ◽  
Linear Regression Analysis ◽  
Fast Method ◽  
Immunoaffinity Column ◽  
Simple Method ◽  
Relative Standard ◽  
Certified Value

An effective and fast method for determination of deoxynivalenol (DON) in cereals and flours has been developed. The immunoaffinity column was used for the isolation of DON from wheat, corn, rice and flour extract. The determination was carried out by using the HPLC/UV method. The limit of detection was 0.02 mg/kg. The recoveries for the assay range 0.1 to 2 mg/kg were generally higher than 80%, ranging from 83 to 96% with an average relative standard deviation of 3.8%. The trueness of the method using the DON test – HPLC column was established by use of certified reference material CRM 379. The certified value was 0.67 mg/kg. The result obtained from three replicates was 0.68 ± 0.05 mg/kg. The corresponding confidence interval at 95% probability ranged from 0.63 to 0.73 mg/kg. A comparative study of the DON testTM – HPLC/UV and the Mycosep 225 – GC/ECD methods was carried out. Six naturally contaminated wheat samples were analysed by both methods. Linear regression analysis demonstrates that DON testTM – HPLC is a statistically significant predictor of the GC/ECD method using the Romer Mycosep 225 column.  

Fluorometric and colorimetric enzymic determination of triglycerides (triacylglycerols) in serum.

1980 ◽  
Vol 26 (5) ◽  
pp. 613-617
Author(s):  
H Winartasaputra ◽  
V N Mallet ◽  
S S Kuan ◽  
G G Guilbault
Keyword(s):  
Colorimetric Method ◽  
Glycerol Dehydrogenase ◽  
Tetrazolium Salt ◽  
Fluorometric Method ◽  
Serum Samples ◽  
Fluorescent Compound ◽  
Microbial Lipase ◽  
Colored Compound ◽  
Colorimetric Procedure

Abstract We describe two fully enzymic methods, fluorometric and colorimetric, for determination of triglycerides (triacylglycerols) in serum. Samples are incubated with microbial lipase for 10 min, and the glycerol released from the triglycerides is oxidized by NAD+ in the presence of glycerol dehydrogenase. In the fluorometric method, the resulting NADH is in turn oxidized by resazurin as catalyzed by diaphorase to form resorufin, a highly fluorescent compound. In the colorimetric method, the NADH is oxidized by coupling with a tetrazolium salt/diaphorase system to form formazan, a highly colored compound. Calibration curves, constructed by plotting change in fluorescence or absorbance vs concentration of triglycerides, were linear up to 6 and 5 g of triglycerides per liter of serum for the fluorometric and colorimetric methods, respectively. The assays require only 5 and 15 microL of serum for fluorometry and colorimetry, respectively. The CV was 0.59% for the fluorometric method, 0.91% for the colorimetric procedure. The time for analysis for either method is less than 15 min. The results correlate well with those obtained by the Dow Diagnostic Kit method, a colorimetric method in which glycerol kinase and glycerol-1-phosphate dehydrogenase form NADH from ATP and NAD+ in the presence of glycerol and glycerol 1-phosphate.

Automated Fluorometric Determination of Vitamin A in Milk

1978 ◽  
Vol 61 (6) ◽  
pp. 1370-1373
Author(s):  
James N Thompson ◽  
René Madère
Keyword(s):  
Steady State ◽  
Vitamin A ◽  
Colorimetric Method ◽  
Fluorometric Method ◽  
Fluorometric Determination ◽  
Extraction And Separation ◽  
Milk Samples ◽  
Fortified Milk ◽  
Coefficients Of Variation

Abstract A previously published fluorometric method for vitamin A in milk, involving saponification in centrifuge tubes and extraction with hexane, was automated using conventional automated equipment including a filter fluorometer. The extraction and separation steps were affected by the presence of fat, so standards were prepared in milk. The peaks obtained with samples were 95% of steady state values. The coefficients of variation for 10 replicate analyses were 1.9% for unfortified milk and 1.3% for fortified milk. In tests on 19 different milk samples, the results of the automated and manual fluorometric methods differed by less than 10%; a colorimetric method using SbCl3 gave more erratic results and was more lengthy and laborious.

Fluorometric and colorimetric enzymic determination of triglycerides (triacylglycerols) in serum.

1980 ◽  
Vol 26 (5) ◽  
pp. 613-617 ◽  
Author(s):  
H Winartasaputra ◽  
V N Mallet ◽  
S S Kuan ◽  
G G Guilbault
Keyword(s):  
Colorimetric Method ◽  
Glycerol Dehydrogenase ◽  
Tetrazolium Salt ◽  
Fluorometric Method ◽  
Serum Samples ◽  
Fluorescent Compound ◽  
Microbial Lipase ◽  
Colored Compound ◽  
Colorimetric Procedure

Abstract We describe two fully enzymic methods, fluorometric and colorimetric, for determination of triglycerides (triacylglycerols) in serum. Samples are incubated with microbial lipase for 10 min, and the glycerol released from the triglycerides is oxidized by NAD+ in the presence of glycerol dehydrogenase. In the fluorometric method, the resulting NADH is in turn oxidized by resazurin as catalyzed by diaphorase to form resorufin, a highly fluorescent compound. In the colorimetric method, the NADH is oxidized by coupling with a tetrazolium salt/diaphorase system to form formazan, a highly colored compound. Calibration curves, constructed by plotting change in fluorescence or absorbance vs concentration of triglycerides, were linear up to 6 and 5 g of triglycerides per liter of serum for the fluorometric and colorimetric methods, respectively. The assays require only 5 and 15 microL of serum for fluorometry and colorimetry, respectively. The CV was 0.59% for the fluorometric method, 0.91% for the colorimetric procedure. The time for analysis for either method is less than 15 min. The results correlate well with those obtained by the Dow Diagnostic Kit method, a colorimetric method in which glycerol kinase and glycerol-1-phosphate dehydrogenase form NADH from ATP and NAD+ in the presence of glycerol and glycerol 1-phosphate.

Fluorometric Determination of Histamine in Tuna: Development of Method

1977 ◽  
Vol 60 (5) ◽  
pp. 1125-1130 ◽  
Author(s):  
Walter F Staruszkiewicz ◽  
Ellen M Waldron ◽  
John F Bond
Keyword(s):  
Anion Exchange ◽  
Exchange Resin ◽  
Anion Exchange Resin ◽  
Colorimetric Method ◽  
New Method ◽  
Fluorometric Method ◽  
Fluorometric Determination ◽  
Chromatographic Separations ◽  
Accuracy And Precision

Abstract Tuna extracts are treated with an anion exchange resin to remove interfering materials, histamine is derivatized with o-phthalaldehyde, and the fluorescence of the resulting compound is measured fluorometrically. Replicate analyses of acceptable and decomposed tuna packed in oil or water agreed within 1 mg at a level of 10 mg/100 g and within 12 mg at a level of 100 mg/100 g. Recoveries of histamine added to fish were >90 and >83% at levels of 10 and 100 mg/100 g, respectively. The new method is more rapid and specific and is simpler than previous methods because no liquid-liquid extractions or chromatographic separations of histamine are required. The sensitivity of the method allows quantitation of <10 mg histamine/100 g sample. The accuracy and precision of the fluorometric method are comparable to those of the official AOAC colorimetric method.

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