Collaborative Study of a Gravimetric Method for Mercury in Formulations Containing Chlorinated Pesticides

1973 ◽  
Vol 56 (3) ◽  
pp. 572-575
Author(s):  
James E Launer
Keyword(s):  
Standard Deviation ◽  
Close Agreement ◽  
Collaborative Study ◽  
Gravimetric Method ◽  
Test Pair ◽  
H2so4 Solution ◽  
Chlorinated Pesticides ◽  
Mercury Iodide ◽  
Digestion Mixture ◽  
Preliminary Study

Abstract A gravimetric method for mercury was modified and collaboratively studied with formulations containing ~6% phenylmercuric urea and ~7% captan in one test pair and ~2% phenylmercuric urea and 30% lindane in another test pair. Mercury is determined by precipitation and weighing cupric propylene mercury iodide (Cu pn2HgI4), following refluxing with dilute HI-H2SO4 solution containing I2. Single determinations on 4 samples by 11 collaborators showed that the standard deviation estimation of random error was 0.063 for the captan pair and 0.034 for the lindane pair. Standard deviation estimates of systematic error were 0.061 and 0.013, respectively. In the preliminary study, the method showed close agreement with other accepted methods for 15 formulations. Lindane, captan, dieldrin, heptachlor, and zineb do not interfere; however, the method is not applicable to chloro- or nitrophenolic compounds nor to materials not decomposed by the digestion mixture. The method has been adopted as official first action.

Collaborative Study of Modified Elmore Method for Mercury in Formulations

1971 ◽  
Vol 54 (3) ◽  
pp. 685-687
Author(s):  
James E Launer
Keyword(s):  
Standard Deviation ◽  
Systematic Error ◽  
Random Error ◽  
Collaborative Study ◽  
Test Pair ◽  
Titrimetric Method ◽  
Mercuric Nitrate ◽  
Thiocyanate Solution ◽  
Diluted Solution ◽  
Bearing Materials

Abstract The titrimetric method for mercury described by Elmore in 1946 was modified and collaboratively studied with formulations containing 6.7% phenylmercury urea in one test pair and 1% mercuric nitrate in another test pair. Mercury is determined in diluted solution, following reflux at 30 drops/min with fuming H2SO4-red fuming HNO3, by titration with standard thiocyanate solution, using ferric alum as indicator. The method is not applicable in presence of large quantities of chlorine-bearing materials. Single determinations on 4 samples by 14 collaborators showed that the standard deviation estimation of random error was 0.058 for phenylmercury urea and 0.004 for mercuric nitrate. Standard deviation estimates of systematic error were 0.048 and 0.009, respectively. The method has been adopted as official first action.

Determination of Total Dietary Fiber in Foods and Products with Little or No Starch, Nonenzymatic-Gravimetric Method: Collaborative Study

1994 ◽  
Vol 77 (3) ◽  
pp. 687-689 ◽  
Author(s):  
Betty W Li ◽  
Maria S Cardozo
Keyword(s):  
Standard Deviation ◽  
Dietary Fiber ◽  
Fruits And Vegetables ◽  
Simple Procedure ◽  
Collaborative Study ◽  
Gravimetric Method ◽  
Total Dietary Fiber ◽  
Freeze Dried ◽  
Relative Standard

Abstract A collaborative study was conducted to validate a nonenzymatic-gravimetric method for the determination of total dietary fiber (TDF) of samples containing little or no starch such as most fruits, and vegetables and many purified polysaccharides. This simple procedure involves suspension of freeze-dried, ground samples in deionized water and incubation at 37°C for 90 min, followed by pre-cipitation with 4 volumes of 95% ethanol. The weight of the dilute alcohol-insoluble residues after correcting for crude protein and ash corresponds to the TDF content of the sample. Six samples in blind duplicate (apples, apricots, cabbage, carrots, onions, and soy fiber) were sent with Celite to 10 laboratories. The reproducibility relative standard deviation (RSDr) of the TDF values for 9 laboratories ranged from 2.92 to 6.25%. The repeatability standard deviation (RSDr) for the 9 laboratories ranged from 1.50 to 2.70%. The method has been adopted first action by AOAC INTERNATIONAL.

Collaborative Study of the Gravimetric Method for the Determination of Mercury in Chlorinated Pesticide Formulations

1975 ◽  
Vol 58 (1) ◽  
pp. 33-34
Author(s):  
James E Launer
Keyword(s):  
Collaborative Study ◽  
Gravimetric Method ◽  
Chlorinated Pesticides ◽  
Titrimetric Method ◽  
Pesticide Formulations ◽  
Aoac Method

Abstract The official first action AOAC gravimetric method for mercury, 6.C01–6.C03, and the official CIPAC titrimetric method, M2.3, were collaboratively studied by 4 CIPAC laboratories, using the same 4 samples analyzed by AOAC collaboration in 1972. Averages at the 3.7 and 3.4% level were the same by both methods whereas the CIPAC method produced, on the average, 4% higher results, all levels included. The AOAC method performs well in the presence of copper and chlorinated pesticides and is less complex to use than the present CIPAC method for mercury in these mixtures. The method has been adopted as official final action.

Enzymatic-Ultraviolet Method for Measuring Lactose in Milk: Collaborative Study

1984 ◽  
Vol 67 (3) ◽  
pp. 637-640 ◽  
Author(s):  
David O Biltcliffe ◽  
Dick H Kleyn ◽  
J Richard Trout ◽  
◽  
D Azzara ◽  
...  
Keyword(s):  
Food Industry ◽  
Collaborative Study ◽  
Skim Milk ◽  
Gravimetric Method ◽  
T Test ◽  
Enzymatic Method ◽  
Commercial Laboratory ◽  
Aoac Method ◽  
Standard Deviations

Abstract Collaborators in 8 dairy and food industry laboratories performed one lactose determination on each of 8 unknown samples of milk, lowfat milk, or skim milk, as 3 pairs of blind duplicates. Two known samples were provided to gain experience prior to analysis of the unknown samples. All of the above samples were also analyzed for lactose content by the official AOAC gravimetric method (16.507) by a commercial laboratory. From the overall mean of results on all samples, determinations by the enzymatic method averaged 0.49% lower than by the AOAC method. This difference was significant by the t-test (P = 0.05), which indicated a lack of agreement between the compared methods in determining lactose content. Standard deviations were similar for the 3 sets of blind duplicates which ranged between 3.67 and 4.55% lactose content. F-values revealed that variations between means obtained by laboratories differed significantly as compared with variations within laboratory means. The method has been adopted official first action.

Determination of Total, Soluble, and Insoluble Dietary Fiber in Foods—Enzymatic-Gravimetric Method, MES-TRIS Buffer: Collaborative Study

1992 ◽  
Vol 75 (3) ◽  
pp. 395-416 ◽  
Author(s):  
Sungsoo C Lee ◽  
Leon Prosky ◽  
Jonathan W De Vries
Keyword(s):  
Dietary Fiber ◽  
Collaborative Study ◽  
Gravimetric Method ◽  
Tris Buffer ◽  
Total Dietary Fiber ◽  
Method Performance ◽  
Insoluble Dietary Fiber ◽  
Heat Stable ◽  
Assay Precision

Abstract A joint AOAC/AACC (American Association of Cereal Chemists) collaborative study of methods for the determination of soluble, insoluble, and total dietary fiber (SDF, IDF, and TDF) was conducted with 11 participating laboratories. The assay Is based on a modification of the AOAC TDF method 985.29 and the SDF/IDF method collaboratively studied recently by AOAC. The principles of the method are the same as those for the AOAC dietary fiber methods 985.29 and 991.42, Including the use of the same 3 enzymes (heat-stable α-amylase, protease, and amyloglucosldase) and similar enzyme Incubation conditions. In the modification, minor changes have been made to reduce analysis time and to Improve assay precision: (1) MES-TRIS buffer replaces phosphate buffer; (2) one pH adjustment step Is eliminated; and (3) total volumes of reaction mixture and filtration are reduced. Eleven collaborators were sent 20 analytical samples (4 cereal and grain products, 3 fruits, and 3 vegetables) for duplicate blind analysis. The SDF, IDF, and TDF content of the foods tested ranged from 0.53 to 7.17, 0.59 to 60.53, and 1.12 to 67.56 g/100 g, respectively. The respective average RSDR values for SDF, IDF, and TDF determinations by direct measurements were 13.1, 5.2, and 4.5%. The TDF values calculated by summing SDF and IDF were in excellent agreement with the TDF values measured independently. The modification did not alter the method performance with regard to mean dietary fiber values, yet It generated lower assay variability compared with the unmodified methods. The method for SDF, IDF, and TDF (by summing SDF and IDF) has been adopted first action by AOAC International.

scholarly journals Indirect and Direct Determination of the Casein Content of Milk by Kjeldahl Nitrogen Analysis: Collaborative Study

1998 ◽  
Vol 81 (4) ◽  
pp. 763-774 ◽  
Author(s):  
Joanna M Lynch ◽  
David M Barbano ◽  
J Richard Fleming
Keyword(s):  
Standard Deviation ◽  
Nitrogen Content ◽  
Relative Standard Deviation ◽  
Collaborative Study ◽  
Direct Determination ◽  
Raw Milk ◽  
Method Performance ◽  
Relative Standard ◽  
Milk Casein

Abstract The classic method for determination of milk casein is based on precipitation of casein at pH 4.6. Precipitated milk casein is removed by filtration and the nitrogen content of either the precipitate (direct casein method) or filtrate (noncasein nitrogen; NCN) is determined by Kjeldahl analysis. For the indirect casein method, milk total nitrogen (TN; Method 991.20) is also determined and casein is calculated as TN minus NCN. Ten laboratories tested 9 pairs of blind duplicate raw milk materials with a casein range of 2.42- 3.05℅ by both the direct and indirect casein methods. Statistical performance expressed in protein equivalents (nitrogen ⨯ 6.38) with invalid and outlier data removed was as follows: NCN method (wt%), mean = 0.762, sr = 0.010, SR = 0.016, repeatability relative standard deviation (RSDr) = 1.287℅, reproducibility relative standard deviation (RSDR) = 2.146%; indirect casein method (wt℅), mean = 2.585, repeatability = 0.015, reproducibility = 0.022, RSDr = 0.560℅, RSDR = 0.841; direct casein method (wt℅), mean = 2.575, sr = 0.015, sR = 0.025, RSDr = 0.597℅, RSDR = 0.988℅. Method performance was acceptable and comparable to similar Kjeldahl methods for determining nitrogen content of milk (Methods 991.20, 991.21,991.22, 991.23). The direct casein, indirect casein, and noncasein nitrogen methods have been adopted by AOAC INTERNATIONAL.

scholarly journals A preliminary study of fecundity of whiting, Merlangius merlangus euxinus (Linnaeus, 1758) in coast of Tirebolu (Eastern Black Sea)

2018 ◽  
Vol 6 (3) ◽  
pp. 322
Author(s):  
Burcu Taylan ◽  
Sule Gurkan ◽  
Ertan Taskavak ◽  
Arzu Aydın Uncumusaoglu
Keyword(s):  
Linear Relationship ◽  
Black Sea ◽  
Gravimetric Method ◽  
The Third ◽  
Ovary Weight ◽  
Total Length ◽  
Total Fecundity ◽  
Maturation Stages ◽  
Preliminary Study ◽  
Merlangius Merlangus

In this research, a preliminary study was carried out in January and February 2014 to determine the fecundity of the whiting species in Tirebolu, Eastern Black Sea. After the total length (cm) and weight (0.01 g) of the 70 fish specimens were measured in the laboratory, they were dissected for sex determination. Using the 20 ovaries at the third and fourth maturation stages, 3 sub-samples which is 2-5% of the total ovary weight (from the anterior, median and posterior parts of the ovary) were taken from each ovary to determine the fecundity, and hydrated oocytes were counted with gravimetric method. Total fecundity, total oocytes number in the ovary were computed with the formula F=(n×G)/g. The total length-weight values were 12.6-23.3 cm (mean 17.08±2.12) and 15.59-95.72 g (mean 41.07 ± 16.75), respectively, and total length-weight relationship was computed as W=0.0073L3.024 (R2=0.94) for the 70 fishes evaluated. Fecundity was computed as 3.247-30.534 (mean: 10.139±6.953) eggs and a linear relationship between fecundity and total length was calculated as F=0.0186L4.5631 (R2=0.70). In conclusion, the fecundity results of this prelaminar study were compared with similar studies on the whiting species from Black Sea and other seas.

Determination of Maleic Hydrazide Residues in Tobacco and Vegetables

1973 ◽  
Vol 56 (5) ◽  
pp. 1164-1172
Author(s):  
Milan Ihnat ◽  
Robert J Westerby ◽  
Israel Hoffman
Keyword(s):  
Standard Deviation ◽  
Present Method ◽  
Maleic Hydrazide ◽  
Collaborative Study ◽  
Official Method ◽  
Sample Weight ◽  
Relative Standard ◽  
The Mean ◽  
Pipe Tobacco

Abstract The distillation-spectrophotometric method of Hoffman for determining maleic hydrazide has been modified to include a double distillation and was applied to the determination of 1–30 ppm maleic hydrazide residues in tobacco and vegetables. Recoveries of 1–23 μg added maleic hydrazide were independent of weight of maleic hydrazide, but did depend on sample and sample weight. The following recoveries were obtained from 0.5 g sample: pipe tobacco, 84%; commercially dehydrated potato, 83%; cigar tobacco, 81%; dried potato, 76%; fluecured tobacco, 73%; dried carrot, 71%. In the absence of sample, the recovery was 82%. When appropriate standard curves were used, maleic hydrazide levels determined in tobacco samples were essentially independent of sample weight in the range 0.1–3 g. The mean relative standard deviation for a variety of field-treated and fortified tobacco samples containing 1–28 ppm maleic hydrazide was 3%. The precision and sensitivity of this procedure seem to be substantial improvements over official method 29.111–29.117. It is recommended that the present method be subjected to a collaborative study.

scholarly journals Liquid Chromatographic Determination of Ampicillin Residues in Porcine Muscle Tissue by a Multipenicillin Analytical Method: European Collaborative Study

2002 ◽  
Vol 85 (4) ◽  
pp. 889-900 ◽  
Author(s):  
Eric Verdon ◽  
Pierric Couëdor ◽  
Pierre Maris ◽  
Michel Laurentie ◽  
P Batjoens ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Muscle Tissue ◽  
Phosphate Buffer ◽  
Collaborative Study ◽  
Porcine Muscle ◽  
Relative Standard ◽  
Liquid Chromatographic

Abstract A collaborative study involving 14 laboratories was conducted to determine residues of ampicillin in porcine muscle tissue by using a liquid chromatographic method developed for multipenicillin analysis that can quantitate 8 penicillin compounds (benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, nafcillin, oxacillin, cloxacillin, and dicloxacillin) at trace levels in muscle tissue. This method involves extraction of the penicillins with phosphate buffer, pH 9, followed cleanup and concentration on a C18 solid-phase extraction column and reaction with benzoic anhydride at 50°C and with 1,2,4-triazole and mercury(II) chloride solution, pH 9.0, at 65°C. The derivatized compounds are eluted isocratically on a C8 column with a mobile phase of acetonitrile and phosphate buffer (pH 6; 0.1M) containing sodium thiosulfate and the ion-pair reagent tetrabutylammonium hydrogen sulfate. The penicillins are detected by UV absorption at 325 nm. The limit of detection and the limit of determination (quantitation) of the method were calculated to be approximately 3–5 and 25 μg/kg, respectively, in accordance with the criteria of European Union (EU) Decision No. 93/256/EEC. In this first interlaboratory study, collaborators were instructed to monitor 4 different penicillin compounds (benzylpenicillin, phenoxymethylpenicillin, ampicillin, and amoxicillin) by analyzing 8 blind samples of muscle tissue in triplicate. These samples were prepared from 2 materials containing different concentrations of incurred ampicillin (63.5 μg/kg for material No. 1 and 358.1 μg/kg for material No. 2) and 1 blank material. The repeatability relative standard deviation and the reproducibility relative standard deviation were 10.2 and 17.4%, respectively, for material No. 1 and 7.0 and 16.0%, respectively, for material No. 2. These results demonstrate that the method is suitable for the determination of ampicillin residues in muscle tissue at the EU maximum residue limit (50 μg/kg) and above. However, the identification of positives by this procedure may need additional confirmation by techniques with greater specificity, such as liquid chromatography combined with mass spectrometry, or tandem mass spectrometry. Investigations regarding the basis of interlaboratory testing studies will further demonstrate the suitability of multiresidue methodology for detecting and quantitating other compounds in the family of penicillin antibiotics.

Collaborative Study of a Spiral Vessel Count Method for Estimating Shell in the Chocolate Component of Cocoa and Related Products

1968 ◽  
Vol 51 (3) ◽  
pp. 725-735
Author(s):  
Manion M Jackson
Keyword(s):  
Standard Deviation ◽  
Collaborative Study ◽  
Pectic Acid ◽  
Counting Procedure ◽  
Count Method ◽  
Cocoa Products ◽  
Two Samples ◽  
Borax Solution ◽  
Vessel Count ◽  
Microscopic Counting

Abstract Part-I: The spiral vessel count method for estimating pectic acid in cocoa has been modified to replace the saturated borax solution by 4% NaOH, which gives a clearer product to count, and to include a method for preparing the sample dry fat-free and 250 mesh before analyzing, by hand grinding or grinding by two different grinders. Counts have been made on known shell in the chocolate component mixtures. A formula usable in a 1—15% range and standard curves have been prepared for the estimation of shell in the chocolate component. Counts have been taken at 100X and 200x on a 0.2 g/100 ml concentration, and at 200X on a 0.35 g/50 ml concentration; 200X counting of the higher concentration is preferred for 1—15% shell. Cocoas of known pectic acid content were analyzed by the method and per cent shell found by spiral vessel counts compared with per cent pectic acid. These cocoas were also analyzed before being made 250 mesh for comparative purposes. An intralaboratory study was made on two samples. Part-II: A collaborative study for determining per cent shell by the spiral vessel count method was made on four samples of cocoa products by six collaborators; two samples were defatted and ground to 250 mesh, the other two samples were hand-ground. Five collaborators varied less than 1 standard deviation unit from the average on the four subdivisions; one collaborator was just outside the standard deviation on one sample. The precision of the results was within a reasonable range for a microscopic counting procedure, and the method has been recommended for adoption as official, first action.

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