Standard filter, preparation

Haartz, Bolyard and Abell ( 3.) used atomic absorption spectrophotometry to check filter standards prepared by the suspension technique Zinc oxide was "spiked" on DM-800 filters and quantitated by AAS and XRD Results from these measurements are shown in Table II, An average deviation of 2 1% was found between the two techniques. Although this data does give a considerable degree of confidence to the use of the suspension procedure for standards preparation, additional data for other analytes is needed for conclusive proof. 

Procedure. Prepare a 0.25 per cent solution of diphenylcarbazide in 50 per cent acetone as required. The test solution may contain from 0.2 to 0.5 part per million of chromate. To about 15 mL of this solution add sufficient 3M sulphuric acid to make the concentration about 0.1M when subsequently diluted to 25 mL, add 1 mL of the diphenylcarbazide reagent and make up to 25 mL with water. Match the colour produced against standards prepared from 0.0002M potassium dichromate solution. A green filter having the transmission maximum at about 540 nm may be used. 

Standard preparation Dissolve an accurately weighed quantity of USP Miconazole Nitrate RS in methanol to obtain a solution having a known concentration of about 500 pg/mL. Transfer 10 mL of this solution to a test tube, and evaporate on a steam bath with the aid of a current of filtered air to dryness. Dissolve the residue in 2 mL of the Internal standard solution. This Standard preparation has a concentration of about 2500 pg/mL. 

An ultraviolet spectrophotometric analysis is used to determine content uniformity of triprolidine hydrochloride in tablet formulations.1 The triprolidine hydrochloride is extracted from finely powdered tablets with dilute hydrochloric acid. The solution is filtered and diluted to a concentration of approximately 10 Jg triprolidine hydrochloride per ml. The absorbance at 290 nm of the extracted triprolidine hydrochloride solution in 1 cm cells is compared against NF Triprolidine Hydrochloride Reference Standard prepared in dilute hydrochloric acid at the 10 pg/ml level. 

Triprolidine hydrochloride in syrups and tablets can be analyzed by fluorimetry. A portion of the tablets or syrup is made basic with IN NaOH and extracted with ethylene chloride. The organic phase is then extracted with 0.1N I SO. The fluorescence of the acid extract is determined with a fluorometer using a UG11 filter for excitation and a Wratten 2A filter for emission. The fluorescence of the sample preparation is compared against a Reference Standard prepared in the same manner22. 

Prepare and filter standard solutions of several of the components shown on the label. The concentrations should be reasonable guesses of what might match what is in the sample. Inject each individually and observe the retention times for each component. Check to see if one of these retention times matches the retention time for a resolved peak from the sample. 

Barium Sulphate To 1.0 g add a mixture of 3 ml 2M HNOs and 7 ml DW, heat on a water-bath for 5 minutes, filter, dilute the filtrate to 10 ml with DW, add 5 ml molybdovanadic reagent and allow to stand for 5 minutes. Any yellow colour produced is not more intense than that of a standard prepared simultaneously and in the same manner using 10 ml of phosphate standard solution (= 5 ppm P04) (50 ppm). 

Sample and Standards Preparation. Shellfish samples were extracted by the standard bioassay procedure (1). Prior to injection into the HPLC, protein was precipitated with 1.5% TCA at I C (60ul) 50% TCA to 2 ml extract). The samples were then centrifuged, an aliquot diluted 1 3 with water and filtered (. 5 urn). 

Dilute citrus juice (5 ml) with dimethylformamide (DMF, 10 ml) and 50 mM ammonium oxalate (10 ml), and then steam-bath for 10 min at 90°C. Cooling, adjust the volume to 50 ml with water, centrifuge (10 min at 2500 g), and then filter (Acrodisc, 5 and 0.45 /nm) the clarified juice. For standard preparation, prepare hesperidin (20 ppm) in DMF-water (2 1) solution and other flavanone glycosides (neohesperidin, eriocitrin, neoeriocitrin, naringin, and narirutin, 10 ppm) in the mobile phase. 

Microfiltration is used widely in the pharmaceutical industry to produce injectable drug solutions. Regulating agencies require rigid adherence to standard preparation procedures to ensure a consistent, safe, sterile product. Microfiltration removes particles but, more importantly, all viable bacteria, so a 0.22- xm-rated filter is usually used. Because the cost of validating membrane suppliers is substantial, users usually develop long-term relationships with individual suppliers. 

Dissolved metals are the concentrations of metals determined in a water sample after it has been filtered through a 0.45 pm filter and acidified with nitric acid immediately after filtering. Samples prepared in this manner do not need to be digested as long as the acidity of the sample has been adjusted to match the acidity of the standards. Suspended metals are defined as the concentrations of metals retained by the 0.45 pm filter. A sum of dissolved and suspended metal concentrations is the total metals. 

After sample collection the filter is extracted with basic NaOH/NaCN solution (0.1 M), which dissolves the Ag2S. An aliquot of the fluorescent complex fluorescein mercuric acetate (FMA) is added to the solution and the fluorescence (500 nm excitation/520 nm emission) of the solution is determined. The presence of sulfide in the solution results in quenching of the fluorescence of the FMA solution, presumably as a result of the interaction of sulfide with the mercuric ion. The sulfide concentration is determined by measuring the decrease in fluorescence relative to that of a blank filter extracL Calibration is done by adding successive aliquots of a fresh aqueous Na2S standard (prepared in 0.1 M NaOH) to a blank filter extract. 

There are two basic laboratory methods for the preparation of filter standards--dust generation and the liquid suspension technique. Dust generation has a distinct advantage because of the ability to produce atmospheres similar to the workplace which can then be... 

These data were obtained by die National Institute of Standards and Technology (USA) while developing a transfer standard for verification and calibration of die v-axis of NIR speedometers. Optical filters were prepared from two separate melts, 2035 and 2035a, of a rare eardi glass. Filters from both melts provide seven well-suited adsorption bands of very similar but not exactly identical location. One filter, Y, from one of die two melts was discovered to be unlabelled. Four 2035 filters and one 2035a filter were available at die time of diis discovery. Six replicate speeda were taken from each filter. Band location data from these spectra are provided below, in cm-1. The expected location uncertainties range from 0.03 to 0.3 cm-1. 

Standard Preparations Dissolve 338.5 mg of mercuric chloride, in about 200 mL of water in a 250-mL volumetric flask, add 14 mL of 1 2 sulfuric acid, dilute to volume with water, and mix. Pipet 10.0 mL of this solution into a 1000-mL volumetric flask containing about 800 mL of water and 56 mL of 1 2 sulfuric acid, dilute to volume with water, and mix. Pipet 10.0 mL of the second solution into a second 1000-mL volumetric flask containing 800 mL of water and 56 mL of 1 2 sulfuric acid, dilute to volume with water, and mix. Each milliliter of this diluted stock solution contains 0.1 pig of mercury. Pipet 1.25, 2.50, 5.00, 7.50, and 10.00 mL of the last solution (equivalent to 0.125, 0.250, 0.500, 0.750, and 1.00 ptg of mercury, respectively) into five separate 150-mL beakers. Add 25 mL of aqua regia to each beaker, cover with watch glasses, heat just to boiling, simmer for about 5 min, and cool to room temperature. Transfer the solutions into separate 250-mL volumetric flasks, dilute to volume with water, and mix. Transfer a 50.0-mL aliquot from each solution into five separate 150-mL beakers, and add 1.0 mL of 1 5 sulfuric acid and 1.0 mL of a filtered solution of 1 25 potassium permanganate solution to each. Heat the solutions just to boiling, simmer for about 5 min, and cool. 

Procedure (Note Refer to Lead Limit Test, Appendix TTTR, for the solutions and the control.) Add 3 mL of Ammonium Citrate Solution and 0.5 mL of Hydroxylamine Hydrochloride Solution to the Sample Solution, and make the combined solutions alkaline to phenol red TS with ammonium hydroxide. Add 10 mL of Potassium Cyanide Solution. Immediately extract the solution with successive 5-mL portions of Dithizone Extraction Solution, draining off each extract into another separator, until the last portion of dithizone solution retains its green color. Shake the combined extracts for 30 s with 20 mL of 1 100 nitric acid, and discard the chloroform layer. Add exactly 4 mL of Ammonia-Cyanide Solution and 2 drops of Hydroxylamine Hydrochloride Solution to the acid solution. Add 10 mL of Standard Dithizone Solution, and shake the mixture for 30 s. Filter the chloroform layer through an acid-washed filter paper into a Nessler tube, and compare the color with that of a standard prepared as follows Add 0.25 mL of the Standard Lead Solution containing 10 p,g/mL of lead (Pb) ion, 4 mL of Ammonia-Cyanide Solution, and 2 drops of Hydroxylamine Hydrochloride Solution to 20 mL of 1 100 nitric acid, and shake for 30 s with 10 mL of Standard Dithizone Solution. Filter through an acid-washed filter paper into a Nessler tube. The color of the Sample Solution does not exceed that in the control. 

Standard Preparation Transfer about 20 mg of USP Natamycin Reference Standard, accurately weighed, into a 100-mL volumetric flask. Add 5.0 mL of tetrahydrofuran, and sonicate for 10 min. Add 60 mL of methanol, and swirl to dissolve. Add 25 mL of water, and mix. Allow to cool to room temperature. Dilute to volume with water, mix, and filter through a membrane filter of 5-p.m or finer porosity. 

Standard Preparation Transfer about 250 mg of an Olestra sample with known amounts of various esters (from Sigma Chemical, Nu-Chek-Prep, or equivalent), accurately weighed, into a 25-mL volumetric flask. Dissolve and dilute to volume with Mobile Phase A. Filter the solution through a 0.5-p.m filter. 

How to prepare standard acid and base solutions, pp. 43, 44 Common laboratory apparatus for handling and treating samples, p. 44 How to filter and prepare precipitates for gravimetric analysis, p. 48 How to sample solids, hquids, and gases, p. 52 9 How to prepare a solution of the analyte, p. 53... 

In the analysis of particulates in air, the samples are collected by passing measured volumes of air through filter paper (or some other suitable filter media). One method of standardization is to pipette small volumes of solution containing known amounts of the elements to be determined onto the same filter medium. Depending on the energy of the x-ray line and the size of the particulates, there may be systematic errors in the analysis using standards prepared from solutions. Another approach to standardization is to disperse known quantities of elements in the form of finely divided powders onto paper or glass-fiber filters. Problems with this approach include variation in particle size between standards and unknowns, and quantitative collection of the standard powders by the filter. 

Filter standards used for calibration and method assessment were prepared by adding 2 pL drops of standard solutions with concentration of 0-100 mg L onto blank filters. The solutions were prepared in 100 mL acid washed flasks by dilution of a multi-element standard (Merck CertiPUR, 1,000 mg L ) in 18 MQ cm water obtain from a Milli-Q Gradient system (Milhpore, Bedford, MA) with 7 mL eoneentrated nitric acid (65% HNO3, suprapure grade) and 2 mL of a Rhodamine B dye solution (prepared by dissolution of 0.125 g Rhodamine B... 

Fig. 1 Comparison of drop size, drying and acid content for the preparation of filter standards...

Fig. 2 Calibration of Cr, Cu and Pb performed by LA-ICP-MS analysis of spiked filters. Filters standards were prepared on three different days...

Carefully filter approximately 35 mL of the unknown groundwater sample if necessary. Pipette 20 mL of sample and place into a clean 100-mL volumetric beaker. Add reagents as done previously for the calibration standard preparation and adjust to the final volume with DDL... 

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