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PubMed1976

Colorimetry of carbohydrates with m-aminophenol, and its proposed use in measurement of serum amylase activity.

In the reaction of m-aminophenol with carbohydrates in a thiourea/acetic acid reagent, addition of borate suppresses chromogen formation for hexoses and pentoses, and enhances it for disaccharides. All reaction products absorb maximally at 520 nm. The relatively greater intensity of the m-aminophenol/maltose reaction product was used in a saccharogenic method for amylase, with low blank readings. This method is compared with two dye/starch procedures.

Amylases↗
PubMed1984

Rapid colorimetry of zinc in seminal fluid.

This colorimetric method for determination of zinc in seminal liquid is based on the reaction between zinc and 4-(2-pyridylazo)resorcinol in a buffered solution at pH 9.5. It is very simple, fast (approximately equal to 10 min), and economical. It can be used to determine zinc in "whole" semen, seminal plasma, or isolated spermatozoa. We verified its accuracy for sample concentrations up to 0.4 g/L by comparison with a reference method based on atomic absorption spectroscopy of acidic wet-ashed samples. Calcium and magnesium do not interfere, even in concentrations exceeding the physiological values. Between-run precision at a normal concentration of 0.14 g/L is about +/- 7 mg/L; within-run precision at the same concentration is about +/- 2 mg/L.

Humans↗
PubMed1980

[Acid labile aldosteronuria. Comparison of radio-immunoassay and colorimetry (author's transl)].

The daily excretion of aldosteronuria was studied in 87 normal or pathological subjects by 3 methods : one, classical, by thin layer chromatography (TLC), based on a modification of Neher's technic, the others, by radio-immunoassay with or without prior extraction of urinary aldosterone (RIA). The normal subjects receiving a daily sodium intake of 150 nmol excrete 24,9 +/- 3,4 nmol/24 hours of aldosterone (TLC) and 23,0 +/- 4,2, 26,3 +/- 3,7 nmol/24 hours (RIA) respectively. These values are not statistically different, RIA of aldosteronuria appears to be a reliable and simple technic and permits one to carry out a large number of examinations within a short period of time with only one technician.

Addison Disease↗
PubMedDate not supplied

Determination of total phosphorus in foods by colorimetry: summary of NMKL collaborative study.

A collaborative study was conducted to validate a spectrophotometric-colorimetric method for determining total phosphorus in foods. The sample was dry-ashed in the presence of zinc oxide, and total phosphorus content was measured colorimetrically as molybdenum blue. Twelve laboratories from the Nordic countries participated in the study. The test materials included potato flour, sausage, cold ham, infant formula powder, cheese, and skimmed milk powder. Participants received 12 randomly coded samples of 2 blind duplicates of each material. Phosphorus contents of materials varied between 0.076 and 0.96 g/100 g. Relative standard deviations for repeatability of the method varied from 1.1% for 0.96 g phosphorus/100 g to 5.4% for 0.29 g phosphorus/100 g. Relative standard deviations for reproducibility varied from 3.6% for 0.96 g phosphorus/100 g to 7.7% for 0.23 g phosphorus/100 g. The colorimetric method for determination of total phosphorus in foods has been adopted first action by AOAC INTERNATIONAL as an NMKL/AOAC INTERNATIONAL method.

Food Analysis↗
PubMed1999

Treatment of photosensitive epilepsy using coloured glasses.

A recently introduced optometric technique, colorimetry, enables the perceptual effects of ophthalmic tints to be evaluated subjectively, optimized, and then prescribed in tinted spectacles. The new technique is beneficial in reducing visual stress in patients with dyslexia and migraine. We describe an open trial designed to ascertain: (1) whether the colorimetry assessment, as it is now given, is safe for the investigation of photosensitive patients in optometry clinics where colorimetry equipment is most readily available, but where EEG control is not practical; (2) what proportion of patients with photosensitive epilepsy is likely to benefit to the extent already described in individual cases; (3) whether a tint selected by colorimetry could be shown to reduce the incidence of paroxysmal epileptiform EEG activity in response to flicker and patterns, thereby validating the subjective methods and corroborating the reported seizure reduction. Twenty-four females and nine males (aged 12-43 years) took part. All the patients had suffered visually-provoked seizures, had exhibited a photoparoxysmal response on at least one previous EEG recording, and had received a diagnosis of photosensitive epilepsy. Twenty-two were currently experiencing seizures. A further EEG was recorded in all except seven cases: a routine resting record, followed by hyperventilation. Colorimetry was performed after hyperventilation and before photic stimulation. Twenty-three (70%) reported beneficial effects during colorimetry and were prescribed glasses. There was a preponderance of lenses with a rose or purple colour, in contrast to patients with dyslexia. Seventeen of the 23 patients were available at follow-up, an average of 2.4 years later. Thirteen (57%) reported benefits, and said they were still using the lenses. In six of the 13 the benefits were pronounced, including a reduction of dizziness from fluorescent lighting, elimination of aura when using computer screens etc. Only in three cases was there a reduction in seizures that could reasonably be attributed to the use of lenses; in two of these cases no medications were prescribed, and in the third the medications remained unchanged for four years, two before and two after the introduction of the glasses. In an additional four cases a reduction in seizures was observed but medication had been changed. There was a modest reduction in EEG photosensitivity with the coloured lenses but also to an equivalent or lesser extent with grey in all of the eight patients examined in this way. One patient had seizures during colorimetry, but the seizures were not accompanied by scalp EEG changes.

Adolescent↗
PubMed2005

Comparison of colorimetric and HPLC methods for determination of delta-aminolevulinic acid in urine with reference to dose-response relationship in occupational exposure to lead.

Both traditional colorimetry and recently developed HPLC-fluorometry have been in use for determination of delta-aminolevulinic acid in urine (ALA-U), an effect marker of occupational exposure to lead (Pb). The present study was initiated to compare the values by the two methods on an epidemiology basis among workers occupationally exposed to lead (Pb), to estimate quantitatively the colorimetry-associated increment over the values by the HPLC method, to evaluate ALA-U determination in occupational health service for Pb-exposed workers, and to identify a critical Pb-B to induce an elevation in ALA-U. For this purpose, blood and urine samples were collected from three groups of Pb-exposed workers (both men and women in combination, including smokers) and analyzed for Pb in blood (Pb-B; measured in all subjects) and ALA-U (by colorimetry or HPLC), i.e., Group 1 (164 subjects with urinalysis by the two methods), Group 2 (2,923 subjects by colorimetry), and Group 3 (2,540 subjects by HPLC). ALA-U when measured by colorimetry was higher than the values by HPLC, and that the mean difference on a group basis was 1.4 mg/l (in a range of 1.1 to 1.8 mg/l), irrespective of Pb-B levels. It was also found that the increase in ALA-U was small when Pb-B was relatively low (e.g., < or = 40 microg/100 ml), and that the increase on a group basis in response to an increase in Pb-B from 5 to 40 microg/100 ml was as small as < or = 0.6 mg/l. Thus, ALA-U appeared to be not a sensitive marker of Pb effects at low Pb-B levels. ALA-U however increased substantially with a point of inflection at the Pb-B level of about 17-34 microg/100 ml. Thus it was concluded that ALA-U as measured by colorimetry is greater than ALA-U by HPLC by 1.4 mg/l on average irrespective of intensity of Pb-exposure, which may induce bias in evaluation of health effect, and that ALA-U levels will increase when Pb-B is in excess of 17-34 microg/100 ml.

Adult↗
PubMed2004

1H NMR spectroscopic method for diagnosis of malabsorption syndrome: a pilot study.

Despite its well-documented limitations, colorimetry has been commonly used for the d-xylose test in the diagnosis of malabsorption syndrome (MAS). With a possibility of overcoming its limitations, the use of (1)H NMR spectroscopy for D-xylose test is explored herein. Urine samples from 35 adults with suspected MAS were obtained before and after oral ingestion of D-xylose. The diagnosis of MAS was based on fecal fat (72 h excretion using Van de Kamer's technique, normal < 7 g/24 h and/or Sudan III stain of spot stool specimen, normal or=1 g/5 g/5 h). In vitro experiments on the standard specimens of D-xylose were also performed independently using both methods. Colorimetry showed a lower value for the quantity of D-xylose excreted in urine than NMR [median 0.73 (0.17-1.89 g) vs 1.37 (0.17-3.23 g), respectively; p<0.0001, Wilcoxon's signed ranks test]. Colorimetry and NMR correctly diagnosed 11/12 and 10/12 (p=N.S.) patients with MAS and 14/23 and 20/23 (p<0.05) without MAS, respectively. Sensitivity and specificity of colorimetry and NMR were 91.6 and 60.7% vs 83.3 and 86.9%, respectively. In in vitro experiments, the values obtained for standard xylose using NMR showed a maximum error of 7%, whereas the colorimetric method showed 20%. The NMR method is simple and may be more accurate for the D-xylose absorption test. Colorimetry was found to be inferior as compared with NMR due to its low specificity.

Adolescent↗
PubMedDate not supplied

Methods of analysis for toxic elements in food products. 2. Review of USSR standards on determinations of heavy metals and arsenic.

Methods of analysis prescribed by USSR standards for Hg, Pb, Zn, As, Cd, Cu, Fe, and Sn in foods are described: for Hg--colorimetry of tetraiodide mercurate and atomic absorption spectroscopy (AAS); for Pb, Cd, Zn, and Cu--polarography; for Cu--colorimetry with sodium diethyldithiocarbamate and zinc dibenzyldithiocarbamate; for As--colorimetry with silver diethyldithiocarbamate; for Sn--colorimetry with quercetin; and for Fe--colorimetry with o-phenanthroline. All of the methods have the necessary metrological characteristics, including intralaboratory repeatability value (r), interlaboratory reproducibility value (R), minimum quantity of the element to be determined in the analytical test portion (MQSM), and the coefficients that account for mercury and arsenic losses during analysis. Establishing constant r- and R-values for the methods under consideration is expedient because (a) the methods suggested are used for safety purposes; and (b) the optimum amount of the element studied in the test sample is determined, to a certain degree, by the mass of the test portion.

Arsenic↗
PubMed2002

Note on the methods for determination of chromic oxide in shrimp feeds.

Chromic oxide is used as an inert marker to measure apparent digestibility of feeds in insects, terrestrial, and aquatic animals. Quantitative determination of chromic oxide content in the sample requires the oxidation of water insoluble trivalent chromic oxide to its water-soluble hexavalent form. The two commonly used oxidizing agents are 70% perchloric acid or a mixture of sodium molybdate, sulfuric, and perchloric acid. Chromic oxide content of the oxidized solution is then measured against known standards either directly by spectrophotometry in the visible range at 350, 370, or 440 nm or after forming a colored complex with diphenylcarbazide (DPC) by colorimetry at 540 nm. This study compared the two methods of oxidation followed by spectrophotometry at the three wavelengths and by DPC colorimetry. DPC colorimetry gave precise results than the direct measurement of dichromate ion, irrespective of the method of oxidation used. Ash from samples oxidized by perchloric acid and quantified by DPC colorimetry gave a better measure of actual chromic oxide content as compared to the other methods tested.

Animal Feed↗
PubMed1990

Evaluation of tetrazolium-based semiautomatic colorimetric assay for measurement of human antitumor cytotoxicity.

A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-based colorimetric assay was developed and compared with 51Cr release from different adherent tumor cell targets (human squamous cell carcinoma lines of the head and neck established in our laboratory, melanoma, and colorectal carcinoma) using 5-7-day human lymphokine-activated killer cells and monocyte-depleted peripheral blood lymphocytes as effectors. With adherent tumor cell targets, MTT colorimetry was more sensitive than the 51Cr release assay in measuring the antitumor activity of effectors: median, 4385 (range, 988-8144) versus median, 1061 (range, 582-7294) lytic units (the number of effector cells required to lyse 20% of 5 x 10(3) targets)/10(7) effectors (P less than 0.01). Background effects (without effector cells) were comparable in 4-h assays (9% versus 10%) between MTT colorimetry and 51Cr release. In 24-h assays, MTT colorimetry showed higher antitumor activity (70-100% versus 40-60% lysis at 1:1 effector:target cell ratio) but lower background effects (6% versus 38%) than 51Cr release assay. Thus, MTT colorimetry was more sensitive, did not use radiolabeled targets, required fewer effector cells, and was easier, less expensive, and better adaptable to serial monitoring of effector cell function in cancer patients. This colorimetric assay is especially well suited to adherent tumor cell targets. The use of adherent tumor cell monolayers, as opposed to trypsinized single cell suspensions, provides an opportunity to measure interactions of effector cells with enzymatically unaltered solid tumor targets. Because of the greater sensitivity of the colorimetric assay, the transformation of MTT data into lytic units, as commonly used for 51Cr release assays, required an adjustment to avoid the extrapolation based on the exponential fit equation.

Carcinoma, Squamous Cell↗
PubMed2004

Evaluation of variation in serum globulin concentrations in dairy cattle.

BACKGROUND: Several factors may influence the concentration of serum globulins in healthy cows and thereby affect clinical interpretation; however, few studies have addressed sources of variation in globulin values. OBJECTIVES: The purpose of this study was to compare colorimetry-based total serum globulin values with electrophoretically-determined serum globulin fractions and with IgG concentration, and to evaluate diurnal and long-term physiological variation and the effects of lactation and venipuncture site on serum globulin concentrations in Holstein dairy cattle. METHODS: Serum total globulin and albumin concentrations were analyzed by colorimetry and electrophoresis in 86 lactating cows; IgG concentrations were determined by radial immunodiffusion in 41 dry and 34 lactating cows. Serum globulins were analyzed hourly for 24 hours in 8 lactating cows and weekly for 15 weeks in 6 additional cows. Globulin concentrations were compared in samples obtained from jugular and coccygeal venipuncture sites in 4 cows. Results were analyzed using parametric statistical tests. RESULTS: Colorimetry-based total serum globulin concentrations correlated well with gamma-globulin fractions (r2 = 0.87) and IgG concentrations (r2 = 0.91). Diurnal variation of total serum globulins concentration was significant (P =.01); however, globulins did not vary significantly over a 15-week period. Mean serum globulins concentration in samples obtained from the jugular vein was 2.35 g/L higher than that in samples obtained by coccygeal venipuncture (P <.0001). CONCLUSIONS: The colorimetric method used widely in routine laboratory analyses remains a useful test for globulins determination in dairy cattle. However, time of sampling and venipuncture site should be considered in the interpretation of serum globulins on serial or interindividual specimens.

Animals↗
PubMed1993

[Stability of allantoin and identification of its degradation compounds].

The stability of allantoin was studied in pH 3.0, 6.0, and 8.0 buffer solutions at 50 degrees C for 55 d. Allantoin was determined by high performance liquid chromatography (HPLC) with a cation exchange mode and colorimetry. The known degradation compounds, allantoic acid and glyoxylic acid, were simultaneously determined by ion chromatography. Urea was determined by HPLC with an ion pair mode. In the stability studies on pH 6.0 and 8.0 solutions, new degradation compounds of allantoin were identified as two growing unknown peaks in the HPLC chromatogram. Isolation of these compounds by preparative HPLC and 1H, 15N and 13C-NMR spectra revealed that they were condensates of allantoin and glyoxylic acid, which also reacted positively in phenylhydrazine colorimetry. The amounts of these compounds were calculated from the determination results of other allantoin related compounds in the buffer solutions and were estimated as the biggest amount among all other compound. As they were found to be stable in an alkaline solution, conditions for hydrolysis in the colorimetric determination of allantoin were further examined. It was found that the longer hydrolysis gave more than 90% recovery in the colorimetry.

Allantoin↗
PubMedDate not supplied

Human-eye versus computerized color matching.

This project compared the difference in color matching between human-eye assessment and computerized colorimetry. Fifty dental personnel were asked to color match Vita Lumin shade tabs to seven different randomly arranged test tabs from the Z100 shade guide. All evaluators were blinded to the shades of the test tabs and were asked to match only body shade of the Vita Lumin tab to the middle third or body of each test tab. The results obtained were subsequently computed into L*a*b* values and compared with results obtained by computerized colorimetry. Results indicate that the difference in color matching between human-eye assessment and computerized colorimetry is shade dependent. Discrepancy was significant for b* coordinates for shades A1 and B2 and L* and b* coordinates for shade C4. For all shades evaluated, color difference between human-eye and computerized color matching is perceivable under clinical settings, as delta E values are greater than 3. There is a need for correction factors in the formal specification of the color-matching software due to the discrepancy between human-eye and computerized colorimetric color matching.

Color↗
PubMed1985

A comparative study of three methods of glycosylated haemoglobin measurements.

This report summarizes our experience with 3 methods of glycosylated haemoglobin (HbA1) determinations. Glycosylated haemoglobin levels were determined using microcolumn chromatography (Boehringer Mannheim), agar gel electrophoresis (Corning GlytracTM) and colorimetry. The HbA1 values for 40 normal controls using chromatography, electrophoresis and colorimetry were 7.31 +/- 0.67 (+/- 1 S.D.), 7.98 +/- 0.81 and 8.54 +/- 1.09% respectively. The intra-assay coefficients of variation were 3.3, 4.5 and 2.0% respectively. There were also good correlations among the 3 methods of HbA1 measurements: electrophoresis vs chromatography, r = 0.91 (p less than 0.001) and electrophoresis vs colorimetry, r = 0.84 (p less than 0.001). Similarly, all 3 methods correlated well with the fasting and mean grouped blood glucose values (p less than 0.001). The chromatographic method is precise and well suited for small sample analysis. The colorimetric method, although the least expensive is labour intensive, suitable only for large batch analysis and in situations where results are not required immediately. The electrophoresis method is also precise, the least labour intensive and well suited for small and large volume laboratories. This study showed that since all 3 methods demonstrated similar precision and good correlation with fasting and grouped blood glucose values, the method of choice will depend on the requirements and support facilities of the individual laboratories.

Blood Glucose↗