HCl-KCl Buffer Research Articles

Statistically designed extractive spectrophotometric determination scheme for bismuth(III) with 2-chlorobenzaldehyde thiocarbohydrazone: Analysis of environmental and real resources

The principle of liquid-liquid extraction followed by spectrophotometric determination of bismuth(III) was elaborated. The yellow complex of bismuth(III) with 2-chlorobenzaldehyde thiocarbohydrazone in presence of potassium iodide is soluble in chloroform and was extracted from HCl-KCl buffer having pH 1.2. The concentration of 2-chlorobenzaldehyde thiocarbohydrazone and potassium iodide ensuring maximum absorbance were optimized well. The effect of foreign ions was also thoroughly elucidated. The maximum absorbance of the complex is witnessed at 420 nm having the values of molar absorptivity and Sandell's sensitivity as 1.086 × 10 4 L mol −1 cm −1 and 0.01923 µg cm −2 , respectively. The Beer's law is obeyed for bismuth(III) concentrations over the range of 4.80 to 16.0 μg mL −1 . The composition of [Bi(III)-2CBTCH-iodide] complex was found to be 1:1:1. The scheme has been applied for the determination of bismuth(III) in environmental and real resources.

In vitro swelling studies in simulated physiological solutions and biocompatibility of NIPAM-based hydrogels with some biochemical parameters of human sera

ABSTRACTIn modern medicine, commonly used biomaterials originating from metals, ceramics and polymers have shown biocompatibility with blood, tissues, cells, etc., in the human body. Polymeric biomaterials are usually understood as polymeric materials and articles made from them which are used in medicine, biotechnology biomedicine, bioengineering, pharmaceutical, veterinary, food industry, agriculture and related fields. In this in vitro study, swellings and the biocompatibility of environmentally sensitive N-isopropyl acrylamide-based (ES) hydrogels such as N-isopropyl acrylamide/acrylamide (ES/0), and N-isopropyl acrylamide/acrylamide/ carboxylic acids (ES/XAc) prepared by free radical polymerization in aqueous solutions has been investigated. Selected carboxylic acids for this study were acrylic, methacrylic, crotonic, itaconic, maleic, mesaconic and aconitic acid. The equilibrium swelling of the hydrogels are investigated in simulated physiological fluids or crystalloid solutions such as HCl-KCl buffer (pH = 1.1), universal buffer (pH = 5.5), phosphate buffer (pH = 7.4), urea, isotonic NaCl, isotonic KCl, 5% dextrose, 5% dextrose+isotonic NaCl, Ringer's lactate, human blood serum and human serum albumin solution at 37°C. For the analysis of biocompatibility, ES hydrogels are incubated in 5 different human sera and their biocompatibilities with some biochemical parameters have been investigated for 24 h at 37°C. No significant differences in values before and after the test procedures have been found. It is therefore concluded that environmentally sensitive N-isopropyl acrylamide-based hydrogels are biocompatible for biochemical parameters of human sera.

New Spectrophotometric Methods for the Determination of p-Aminosalicylic Acid in Tablets

Purpose: To develop a new spectrophotometric method with improved sensitivity and at higher wavelength for the determination of p-aminosalicylic acid in tablets.Methods: Two simple and sensitive spectrophotometric methods (methods A and B) were developed using p-dimethylaminobenzaldehyde (DAB), and p-dimethylaminocinnamaldehyde (DAC) as derivatizing reagents for the determination of p-aminosalicylic acid (PAS) in tablets. The derivatization was carried out using 3M HCl-KCl buffer for DAB and 5M HCl-KCl buffer solutions.Result: The new derivatives of PAS absorbed maximally with bathochromic shift to 460 and 555 nm in the linear concentration range of 0.4 – 2.0 μg/mL with molar absorptivities of 2.4 × 104 and 3.8 × 104 L/mole/cm, respectively, compared to pure PAS which absorbed at λmax of 264 nm with molar absorptivity 7.65 × 103 L/mole/cm in the linear concentration range of 2 - 10 μg/mL. The developed methods were successfully applied to assay PAS in tablets with % recovery of 97.6 ± 1.71 and 98.4 ± 1.45 for methods A and B, respectively.Conclusion: Both PAS derivatives absorb in the visible spectral region. The presence of excipients in pharmaceutical preparations did not interfere in the determination of PAS as PAS-DAB and PAS-DAC derivatives. Both methods can be applied to determine PAS from bulk and various pharmaceutical dosage forms.Keywords: p-Aminosalicylic acid, p-dimethylaminobenzaldehyde, p-dimethylaminocinnamaldehyde, Spectrophotometry

Spectrophotometric Determination of Ultra trace Tri & Hexavalent Chromium by Using on-line Flow Injection Analysis with Dual Pre-concentration Column

An on-line flow injection analysis with dual pre-concentration method was developed to determine the ultra trace tri and hexavalent chromium in water. In this system, the cation and anion pre-concentration columns were combined with a 10-port injection valve and then used to separate and concentrate Cr (III) and Cr (VI) selectively. The two species of concentrated chromium were sequentially eluted and determined by using HCl-KCl buffer of pH 1.8 as an eluent. Cr (III) was oxidized by hydrogen peroxide to Cr (VI). It was detected spectrophotometrically at 548 nm by complexation with DPC (diphenylcarbazide). Several factors such as concentration of <TEX>$H_2O_2$</TEX>, DPC and coil length in reaction condition were optimized. The linear range for Cr (III) and Cr (VI) was 0.1-50 <TEX>${\mu}g$</TEX>/L. The limit of detections (<TEX>$3{\sigma}$</TEX>) of Cr (III) and Cr (VI) were 52 ng/L and 44 ng/L under the optimized FIA system, and their recoveries 98% and 103%, respectively. This method was applied to analyze contamination level of chromium species in tap water, groundwater and bottled water.

Modification of gastric pH in the fasted dog

The aim was to compare the ability of pretreatments to consistently adjust gastric conditions to low or high pH in the fasted state in dogs. Four male Labrador/Labrador-cross dogs weighing 25-35 kg were surgically equipped with a ventricle fistula cannula in the stomach and a jejunal nipple valve stoma. Dogs were fasted overnight before the experiments, with free access to water. The pH in the dogs' stomach was modified either orally with buffers (0.1 mol/l HCl-KCl, 0.05 mol/l glycine-HCl, 0.1 mol/l citrate or 0.1 mol/l BIS-TRIS) or intravenously with pharmacological agents (pentagastrin 4-6 microg/kg, ranitidine 50 mg or omeprazole 1 mg/kg). Intragastric pH was recorded continuously for 2 h with an electrode connected to an ambulatory pH meter. Chyme was collected simultaneously from the jejunal stoma as an approximate measure of gastric emptying. 0.1 mol/l HCl-KCl buffer p.o. and 1 mg/kg omeprazole i.v. attained low and high gastric pH more reproducibly (11/11 and 6/7 experiments met target values of pH < 3 and > 4, respectively) and for a longer duration (average time exceeding target value 90 and 103 min, respectively) than the other buffers and pharmacological pretreatments. The starting pH did not alter the modifiers' capacity to increase or decrease the pH. However, the lag time before chyme appeared at the jejunal stoma appeared to be longer when the pH was low and shorter when the pH was high. To achieve a consistently low gastric pH in fasting dogs, 0.1 mol/l HCl-KCl buffer should be administered orally, 15 min before the dosage form. To elevate the gastric pH reproducibly, omeprazole 1 mg/kg should be administered intravenously at least 90 min before oral administration of the dosage form.

Determination of trace selenium by solid substrate-room temperature phosphorescence enhancing method based on potassium chlorate oxidizing phenyl hydrazine-1,2-dihydroxynaphthalene-3,6-disulfonic acid system

A new method for the determination of trace selenium based on solid substrate-room temperature phosphorimetry (SS-RTP) has been established. This method was based on the fact that in HCl–KCl buffer solution, potassium chlorate could oxidize phenyl hydrazine to form chloridize diazo-ion after being heated at 100 °C for 20 min, and then the diazo-ion reacted with 1,2-dihydroxynaphthalene-3,6-disulfonic acid to form red azo-compound which could emit strong room temperature phosphorescence (RTP) signal on filter paper. Selenium could catalyze potassium chlorate oxidizing the reaction between phenyl hydrazine and 1,2-dihydroxynaphthalene-3,6-disulfonic acid, which caused the sharp enhancement of SS-RTP. Under the optimum condition, the relationship between the phosphorescence emission intensity (Δ I p) and the content of selenium obeyed Beer's law when the concentration of selenium is within the range of 1.60–320 fg spot −1 (or 0.0040–0.80 ng ml −1 with a sample volume of 0.4 μl). The regression equation of working curve can be expressed as Δ I p = 13.12 + 0.4839 C Se(IV) (fg spot −1) ( n = 6), with correlation coefficient r = 0.9991 and a detection limit of 0.28 fg spot −1 (corresponding to a concentration range of 7.0 × 10 −13 g ml −1 Se(IV), n = 11). After 11-fold measurement, R.S.D. were 2.8 and 3.5% for the samples containing 0.0040 and 0.80 ng ml −1 of Se(IV), respectively. This accurate and sensitive method with good repeatability has been successfully applied to the determination of trace selenium in Chinese wolfberry and egg yolk with satisfactory results. The mechanism of the enhancement of phosphorescence was also discussed.

Improved Acid Pretreatment for the Detection of Legionella Species from Environmental Water Samples Using the Plate Culture Method

Acid treatment is performed in the detection of Legionella species from environmental water samples using the plate culture method. The acid treatment functions to eliminate the nontarget heterotrophic bacteria. Usually, an HCL-KCL buffer is used for the acid treatment of samples. However, the buffering capacity of the HCL-KCL buffer is not sufficient to maintain a constant low-pH in highly alkaline samples or highly buffered samples such asthose from cooling towers or spas. Our results show that the pH of various water samples ranged from 2.4 to 7.2 after treatment with an HCL-KCL buffer. We demonstrate here that an acid-phosphate buffer produces a low pH in highly alkaline samples or highly buffered samples. The pH of the water samples ranged from 2.2 to 2.5 after treatment with an acid-phosphate buffer. In the re-sults of the examination of 161 samples, the use of an acid-phosphate buffer instead of an HCL-KCL buffer decreased the effect of non-target heterotrophic bacteria from 3.1% to 1.2%. Therefore, efficient detection of Legionella from samples of varying water quality can be achieved following pretreatment with an acid-phosphate buffer.

環境水由来レジオネラ属菌の検出における有機酸緩衝液前処理の検討

Anti-microbial effect of the pretreatment with various organic acid buffer solutions against co-existing microorganisms which were isolated from cooling-tower water samples along with Legionella spp. was examined. Among several buffer solutions, a 0.1 M potassium citrate-citric acid buffer solution (hereafter, citrate buffer solution, pH 2.2) hardly affected the recovery of Legionella spp., but effectively inhibited the growth of co-existing microorganisms. To evaluate the buffer action of these buffer solutions, pHs of 9 cooling-tower water samples were evaluated after addition of an equal volume of each buffer solution. When a citrate buffer solution. pH 2.2 was combined to a 200-fold concentrated solution of each cooling-tower water sample, the pH of the combined solution became 2.5 to 2.7 and maintained a stably low pH value than that (pH 3.0 to 7.4) obtained after mixture of a 0.2 M HCl-KCl buffer solution (hereafter, HCl buffer solution, pH 2.2), suggesting strong buffer action of the citrate buffer solution, pH 2.2 in the combined solutions. Furthermore, when cooling-tower water samples were pretreated with a citrate buffer solution, pH 2.2, the recovery of Legionella spp. was successful in 7 out of 9 cooling-tower water samples, suggesting 3 times higher recovery rate than that obtained by addition of a HCl buffer solution, pH 2.2 (3 out of 9 cooling-tower water samples).

Physical Properties and Molecular Behavior of Chitosan Films

Chitosan films, varying in molecular weight and degree of deacetylation, were prepared by a casting technique using acetic acid as a dissolving vehicle. The physicochemical properties of the films were characterized. Both molecular weight and degree of deacetylation affected the film properties. Powder X-ray diffraction patterns and differential scanning calorimetry thermograms of all chitosan films indicated their amorphous state to partially crystalline state with thermal degradation temperature lower than 280–300°C. The increase in molecular weight of chitosan would increase the tensile strength and elongation as well as moisture absorption of the films, whereas the increase in degree of deacetylation of chitosan would either increase or decrease the tensile strength of the films depending on its molecular weight. Moreover, the higher the degree of deacetylation of chitosan the more brittle and the less moisture absorption the films became. All chitosan films were soluble in HCl–KCl buffer (pH 1.2), normal saline, and distilled water. They swelled in phosphate buffer (pH 7.4), and cross-linking between chitosan and phosphate anions might occur. Finally, transmission infrared and 13C-NMR spectra supported that chitosan films prepared by using acetic acid as a dissolving were chitosonium acetate films.

Chemical characteristics and relative bioavailability of supplemental organic copper sources for poultry.

Five commercially available organic Cu products and reagent-grade CuSO4 x 5H2O (Cu Sulf) were evaluated by polarographic analysis and solubility in 0.1 M K2HPO4-KH2PO4 buffer (pH 5), 0.2 M HCl-KCl buffer (pH 2), or deionized water. Fractions from these solubility tests were evaluated by gel filtration chromatography for structural integrity. The organic sources were Cu lysine complex (Cu Lys), Cu amino acid chelate (Cu AA), Cu proteinate A (Cu ProA), Cu proteinate B (Cu ProB), and Cu proteinate C (Cu ProC). Separation of peaks in the chromatograms for the soluble Cu fraction from deionized water indicated that 77, 31, 69, 94, and 16% of the Cu remained chelated for the above sources, respectively. Two experiments were conducted to estimate the relative bioavailability of Cu from the organic Cu supplements for chicks when added at high dietary concentrations to practical corn-soybean meal diets. Liver Cu concentration increased (P < 0.0001) as dietary Cu increased in both experiments. When Cu Sulf was assigned a value of 100% as the standard, linear regression slope ratios of log10 liver Cu concentration regressed on added dietary Cu concentration gave estimated relative bioavailability values of 124 +/- 5.1, 122 +/- 5.3, and 111 +/- 6.0 for Cu Lys, Cu AA, and Cu ProC, respectively, in Exp. 1. The bioavailability estimates for Cu Lys and Cu AA were greater (P < 0.05) than that for Cu Sulf. Values in Exp. 2 were 111 +/- 7.6, 109 +/- 8.4, and 105 +/- 7.5 for Cu Lys, Cu ProA, and Cu ProB, respectively, and all sources were similar in value for chicks. Solubility of Cu in pH 2 buffer provided the best prediction of bioavailability (r2 = 0.924). Other indicators of chelation integrity and solubility had little value as predictors of bioavailability (r2 < or = 0.445).

Chemical characteristics and relative bioavailability of supplemental organic zinc sources for poultry and ruminants.

Eight commercially available organic Zn products and reagent-grade ZnSO4 x 7H2O (Zn Sulf) were evaluated by polarographic analysis, and solubility in .1 M K2HPO4-KH2PO4 buffer (pH 5), .2 M HCl-KCl buffer (pH 2), and deionized water. Fractions from these solubility tests were evaluated by gel filtration chromatography for structural integrity. Degree of chelation was generally positively related to chelation effectiveness determined by polarography. The organic sources were Zn methionine complex A (Zn MetA), Zn methionine complex B (Zn MetB), Zn polysaccharide complex (Zn Poly), Zn lysine complex (Zn Lys), Zn amino acid chelate (Zn AA), Zn proteinate A (Zn ProA), Zn proteinate B (Zn ProB), and Zn proteinate C (Zn ProC). Three experiments were conducted to estimate the relative bioavailability of Zn from the organic Zn supplements for chicks and lambs when added at high dietary levels to practical diets. Bone Zn concentration increased (P < .001) as dietary Zn increased in both experiments. When Zn Sulf was assigned a value of 100% as the standard, multiple linear regression slope ratios of bone Zn from chicks fed 3 wk regressed on dietary Zn intake gave estimated relative bioavailability values of 83 +/- 14.6 and 139 +/- 16.9 for Zn AA and Zn ProA, respectively, in Exp. 1 and 94 +/- 11.6, 99 +/- 8.8, and 108 +/- 11.4 for Zn Poly, Zn ProB, and Zn ProC, respectively, in Exp. 2. In Exp. 3, 42 lambs were fed diets containing Zn Sulf, Zn ProA, Zn AA, or Zn MetB for 21 d. Based on multiple linear regression slope ratios of liver, kidney, and pancreas Zn and liver metallothionein concentrations on added dietary Zn, bioavailability estimates relative to 100% for Zn Sulf were 130, 110, and 113 for Zn ProA, Zn AA, and Zn MetB, respectively. Except for Zn ProA, which was greater, the organic Zn supplements had bioavailability values similar to that of Zn Sulf for chicks and lambs. Bioavailability of organic Zn products was inversely related to solubility of Zn in pH 5 buffer in chicks (r2 = .91) and pH 2 buffer in lambs (r2 = .91), but not to an estimate of degree of chelation.

Simultaneous Gas Chromatographic Determination of Carbofuran, Metalaxyl, and Simazine in Soils

A method for extraction, cleanup, and simultaneous gas chromatographic detection of carbofuran, metalaxyl, and simazine in soils has been developed. Pesticide residues were extracted from soil with acetone containing 10% 0.2M HCl-KCl buffer (pH 2.0), cleaned up with methylene chloride-carbonate buffer (pH 10.7) solvent partitioning and solid-phase extraction on disposable silica gel columns, and quantitated with gas chromatography using a Supelcowax 10 megabore capillary column and a nitrogen-selective detector. Method limits of detection were 0.02 microgram/g for the 3 pesticides in surface soils (0-30 cm depths) and 0.02, 0.02, and 0.005 microgram/g in soils below 30 cm (subsoils) for carbofuran, metalaxyl, and simazine, respectively. Recoveries for carbofuran, metalaxyl, and simazine were 92.6 +/- 5.5, 93.6 +/- 5.0, and 88.4 +/- 6.7%, respectively, when soil samples were spiked with pesticide concentrations ranging from 0.02 to 2.0 micrograms/g.

In vitro solubility and in vivo toxicity of gallium arsenide

The in vitro solubilities of gallium arsenide (GaAs) and its metal oxides were arsenic(III) oxide > GaAs ⪢ gallium(III) oxide. GaAs dissolution was also dependent upon the type and concentration of buffer anion. The amount of arsenic dissolved in 12 hr by various aqueous media was 0.2 m phosphate buffer ≥ 0.1 m phosphate buffer > Krebs-Hensleit buffer > distilled H 2O > HClKCl buffer. GaAs was apparently soluble under in vivo conditions. Blood arsenic concentrations in rats 14 days after intratracheal instillation of 10, 30, or 100 mg/kg GaAs were 5.5, 14.3, and 53.6 μg/ml, respectively; gallium was not detected at any doses. An increase in lung wet weight at 14 days was dose dependent with these organs retaining 17 to 42% of the dose as gallium or arsenic. Excretion of gallium and arsenic was limited to the feces. Urinary porphyrin concentrations and body weight, monitored as indices of toxicity, were significantly altered over the 14-day study. The analysis of porphyrins revealed that uroporphyrin replaced coproporphyrin as the primary urinary metabolite. Rats receiving 10, 100, or 1000 mg/kg GaAs po exhibited similar signs of toxicity. Blood arsenic concentrations at 14 days were 3.5, 6.8, and 17.6 μg/ml, respectively. Porphyria was increased, and body weight was decreased at 1000 mg/kg GaAs. These values were equivalent to those obtained with an intratracheal dose of 10 to 30 mg/kg GaAs. Our results showed that pulmonary and po exposure to GaAs resulted in systemic arsenic intoxication. The finding that urinary uroporphyrin concentrations were greater than coproporphyrin concentrations may serve as a sensitive indicator for GaAs exposure.

Fluorimetric determination of aluminium with morin after extraction with isobutyl methyl ketone. Part I. Fluorescence of the aluminium-morin complex in an isobutyl methyl ketone-ethanol-water system

A method for the fluorimetric determination of aluminium with morin (3,5,7,2′,4′-pentahydroxyflavone) in an isobutyl methyl ketone (IBMK)-ethanol-water system is proposed, with a 3-to 4-fold increase in sensitivity over the conventional method. The optimum conditions were found to be as follows: 40% of IBMK, 20% of an aqueous solution containing the aluminium and HCl-KCl to adjust the pH and 40% of methanol-ethanol-water (86 + 9 + 5) solution, which is necessary for the dispersion of the IBMK in water, and in which the reagent, morin, is dissolved. The optimum pH is 3.7–3.8 (HCl-KCl buffer) and the fluorescence is measured after 1 h at 495 nm, with excitation at 418 nm, at 25 °C.Using a morin concentration of 0.005%, the calibration graph is linear for concentrations up to 40 p.p.b., and the limit of detection of the method is 0.2 p.p.b. A study of 17 interfering ions showed that the most important interferences are due to Be2+, Zn2+, Pb2+, Fe3+, Fe3+, Cu2+ and F–, and in most instances it was found that the tolerance limits are higher than with the conventional method for the determination of aluminium with morin.

Inhibition of fungal NADP+-isocitrate dehydrogenase by citric acid.

The variations observed during earlier studies in the activity of NADP+-isocitrate dehydrogenase (EC. 1.1.1.42) in a strain of Aspergillus niger were found to be related to the extent of washing of mycelium. As a result the mycelium washed four times with phosphate buffer (0.05 M, pH 7.5), the enzyme activity present in 4 and 8 days old fungal mycelia increased five- and two-fold, respectively. In vivo studies showed a complete loss of enzyme activity in mycelia resuspended in HCl-KCl buffer (0.02 M, pH 2.2) containing citric acid (13 mM or more). The in vitro studies revealed 50% loss of enzyme activity in presence of 3.6 to 5.2 mM citric acid. However, in case of Aspergillus niger ATCC 1015, which produced less citric acid than the above strain, a much higher citric acid concentration (13 to 26 mM) was required to cause 50% loss of enzyme activity. These findings suggest a correlation between citric acid inhibition of NADP+-isocitrate dehydrogenase and the ability of A. niger to accumulate citric acid in the medium.

Glycans from streptococcal cell walls: An antigenic triheteroglycan of 6-deoxy- l-talose, l-rhamnose and d-galactose from Streptococcus bovis

Two antigenic glycans have been isolated from the cell wall of Streptococcus bovis strain C3 by sequential extraction with HCl-KCl buffer of pH 2 and purified by filtration through Bio-gel. Chemical analysis showed that one glycan is a triheteroglycan of d-galactose, l-rhamnose and 6-deoxy- l-talose in the ratio of 2:1:1 and the other is a diheteroglycan of d-glucose and l-rhamnose in the ratio of 1:1. On the basis of the immunochemical data and the nature of acid hydrolytic products from the triheteroglycan, it is proposed that the triheteroglycan consists of a main chain of alternating rhamnose and 6-deoxy-talose residues with side chains of digalactosyl units. The terminal α-linked galactosyl residues are the immunodeterminants of the glycan. The deoxy sugar, 6-deoxy- l-talose, has not been detected previously in streptococcal cell walls and in S. bovis, this sugar is synthesized via the thymidine diphosphate hexose pathway.

Spectrophotometric determination of L-ascorbic acid.

Abstract A novel quantitative determination of l-ascorbic acid by UV spectrophotometry in a HCl-KCl buffer has been developed. Ascorbic acid (λmax 244 mμ) of over 2×10−5 m can quantitatively be determined by this method. Several oxidizing, reducing, acidic or basic reagents and other organic compounds which may be present together with ascorbic acid in ordinary drugs and drinks do not interfere the determination.

Gas chromatographic detection of in vivo activity of equine infectious anaemia virus.

By making use of the marked response of the electron capture detector, it has been possible to detect the presence of extremely small numbers of bacteria in culture media by gas chromatography (B. M. Mitruka and M. Alexander, Appl. Microbiol. 16:636, 1968). The same technique has been employed for the detection of canine viruses in vitro and in vivo (B. M. Mitruka et al., Science 160:309, 1968). It has now been observed that electron capture-gas chromatographic techniques can be applied to the rapid detection of the in vivo activity of equine infectious anaemia virus. Latent infections caused by this virus can only be shown by the inoculation of infective blood into susceptible horses. Serum samples from five healthy experimental horses were taken at occasional intervals for a 2to 3-month period and at 2-day intervals during the 2 weeks immediately prior to infection. The animals were then inoculated intravenously with 5.0 ml of infective serum from clinical sources. For chromatographic analysis, 2.0 ml of serum was treated with 0.10 ml of 5 N HCI and 1.0 ml of 0.2 M HCl-KCl buffer (pH 2.0); the samples were centrifuged for 15 min at 3,000 x g and the resultant supernatant fluid was extracted three times with 10 ml of ether. A 3.0-,tliter portion of the combined extract, or of the combined extract after concentration, was injected into the instrument. The chromatographic techniques were essentially the same as previously described (Y. Henis et al., Appl. Microbiol. 14:513, 1966; B. M. Mitruka and M. Alexander, Appl. Microbiol. 16:636, 1968). The animals were kept under observation for temperature elevation and changes in hematocrit readings and precipitin tests. A rise in temperature of 2 to 3 C was noted in the animals at 2 to about 4 weeks after inoculation. Animals showing illness had hematocrit readings of 20% or less as determined by packed cell volume, whereas the healthy animals showed readings of 30 to 40%.

Studies on the differentiation of myxovirus induced interferon and endogenous pyrogen from rabbits

The fever curve and interferon titer seen after inoculation of rabbits with myxovirus show striking similarities. The two substances are however not identical. They can be separated partially by gel filtration and totally by fractionated ethanol precipitation. Dialysis against HCl-KCl buffer pH 2.0 and against urea or 2-mercaptoethanol shows that the endogenous pyrogen is considerably more labile than interferon.

Gas chromatographic detection of in vivo activity of equine infectious anaemia virus.

By making use of the marked response of the electron capture detector, it has been possible to detect the presence of extremely small numbers of bacteria in culture media by gas chromatography (B. M. Mitruka and M. Alexander, Appl. Microbiol. 16:636, 1968). The same technique has been employed for the detection of canine viruses in vitro and in vivo (B. M. Mitruka et al., Science 160:309, 1968). It has now been observed that electron capture-gas chromatographic techniques can be applied to the rapid detection of the in vivo activity of equine infectious anaemia virus. Latent infections caused by this virus can only be shown by the inoculation of infective blood into susceptible horses. Serum samples from five healthy experimental horses were taken at occasional intervals for a 2to 3-month period and at 2-day intervals during the 2 weeks immediately prior to infection. The animals were then inoculated intravenously with 5.0 ml of infective serum from clinical sources. For chromatographic analysis, 2.0 ml of serum was treated with 0.10 ml of 5 N HCI and 1.0 ml of 0.2 M HCl-KCl buffer (pH 2.0); the samples were centrifuged for 15 min at 3,000 x g and the resultant supernatant fluid was extracted three times with 10 ml of ether. A 3.0-,tliter portion of the combined extract, or of the combined extract after concentration, was injected into the instrument. The chromatographic techniques were essentially the same as previously described (Y. Henis et al., Appl. Microbiol. 14:513, 1966; B. M. Mitruka and M. Alexander, Appl. Microbiol. 16:636, 1968). The animals were kept under observation for temperature elevation and changes in hematocrit readings and precipitin tests. A rise in temperature of 2 to 3 C was noted in the animals at 2 to about 4 weeks after inoculation. Animals showing illness had hematocrit readings of 20% or less as determined by packed cell volume, whereas the healthy animals showed readings of 30 to 40%.