Tomatoes determination

Determine the pH for each of the following samples, given the recorded peak potential (a) tomato juice, +167 mV (b) tap water, -27 mV (c) coffee, 122 mV. 

The molecular basis for quasi-equivalent packing was revealed by the very first structure determination to high resolution of a spherical virus, tomato bushy stunt virus. The structure of this T = 3 virus was determined to 2.9 A resolution in 1978 by Stephen Harrison and co-workers at Harvard University. The virus shell contains 180 chemically identical polypeptide chains, each of 386 amino acid residues. Each polypeptide chain folds into distinct modules an internal domain R that is disordered in the structure, a region (a) that connects R with the S domain that forms the viral shell, and, finally, a domain P that projects out from the surface. The S and P domains are joined by a hinge region (Figure 16.8). 

Johnson et al. (34) eoupled SEC in the non-aqueous mode (Mieropak TSK gel eluted with tetrahydrofuran) to a gradient RP LC system using aeetonitrile/water for the determination of malathion in tomato plants and lemonin in grapefruit peel. 

Moisture Determinations. Because the moisture content of many fruits and vegetables is an index to maturity and quality, moisture determinations are employed extensively in the grading of raw fruits and vegetables, and in some cases— for example, tomato products—the finished item may be sold on the basis of moisture content. 

Miscellaneous Determinations. Several other problems are deserving of brief mention. The citrus industry, for example, would welcome an improved and more rapid method for determining volatile oil in citrus products. The tomato canning industry could profit by more rapid and accurate methods for determining tomato solids, and also by a method that would predict the increase in viscosity which takes place during concentration. 

VAN HET HOF K H, DE BOER B C, TIJBURG L B, LUCIUS B R, ZIJP I, WEST C E, HAUTVAST J G and WESTRATE J A (2000) Carotenoid bioavailability in humans from tomatoes processed in different ways determined from the carotenoid response in the triglyceride-rich lipoprotein fraction of plasma after a single consumption and in plasma after 4 days of consumption. JNutr 130(5) 1189-96. 

Freeze-dried tomato powders obtained from whole tomato fruits and from their pulp after centrifugation, containing 474 and 5399 pg/g dry weight, respectively, were developed for use as additives for food fortification. Cis isomers of lycopene were determined in only a few smdies. The 5-cis-, 9-cis-, and 13-d5 --El5-d5 -lycopene were the isomers found in commercial tomato products. The structures of lycopene cis isomers are shown in Figure 4.2.1 and the structure of the dll-trans isomer is displayed in Figure 6.2.1 in Chapter 6. 

Association of pigment accumulation with DNA features can inform systematics and applied breeding in crop plants. For carotenoid content among crop plants, maize and tomato are best studied by this technique. Because there is interest in accumulation of various intermediate products in the pathway as well as end products, QTLs were developed for genetic determinates that are not independent of each other. Some QTLs affect multiple pigment contents. 

Thorup et al. exploited the microsynteny of beU pepper and tomato and cloned candidate genes from each to determine correspondence of QTL. A comparative approach across species places consensus QTLs, candidate genes, and biochemistry in a phyletic perspective avoiding uncertainties associated with environmental and ontogenic variation in traits. 

The PE2 isoform has been purified and fully sequenced (Markovic and Joumval 1986). Using this sequence data Ray et al (1988) succeeded in isolating a clone fi om a tomato fruit cDNA library. The predicted amino acid sequence fi om this clone had high homology to the actual amino acid sequence determined for PE2 but was not identical. Subsequent screening of the tomato... 

Ray,J.,Knapp,J.,Grierson,D.,Bird,C and Schuch,W. (1988) Identification and sequence determination of a cDNA clone for tomato pectinesterase. European Journal of Biochemistry. 174. 119-124. 

As an example of the capabilities of a combination of INAA and RNAA using a two group separation scheme for the simultaneous determination of As, Cd, Cu, Mo, Sb, Hg, and Se (Kucera and Soukal 1993), and a single separation procedure for vanadium determination (Byrne and Kucera 1991), Table 3.8 shows results for NIST-SRM-i573a Tomato Leaves that were obtained prior to certification of this material (Kucera 1995), and later on taken into consideration for deriving the NIST certified and information values (Becker 1995, personal communication). 

Residual pendimethalin in various crops was determined as follows." A 10-20-g amount of fruits or vegetables was extracted by blending twice with 200 mL of methanol. Grasses and mint were extracted with 200 mL of methanol-water (1 1, v/v). Nuts were extracted with 200 mL of n-hexane-2-propanol (3 1, v/v). For the residue analysis of the dinitroaniline herbicides butralin, dinitramine, ethalfluralin, pendimethalin, and trifluralin, a tomato sample (5 g) was extracted twice with 20 mL of methanol in a Sorvall homogenizer and filtered through filter paper. Benfluralin and trifluralin residues in the sample (10 g) were extracted with 100 mL of acetonitrile-water (99 1, v/v) in 250-mL screw-cap jars with Teflon liners rotated for 1 h on an end-over-end shaker (40 rpm). ... 

The recoveries of five herbicides (ethalfluralin, trifluralin, dinitramine, butralin, and pendimethalin) added to tomato in the range 0.1 to 1 mgkg were determined using GC-ITD. The average recoveries ranged from 84 to 104%, and the detection limit of these compounds was near 0.01 mg kg ... 

In addition to HPLC/fluorescence, there are references to the use of both APCI and/or ESI with HPLC/MS for the determination of A/-methyl carbamate insecticides in a variety of matrices." Ongoing studies at the US EPA for the determination of /V-methyl carbamate insecticides in nine fmits and vegetables at the 1.0 ngg level are described below. The fruits and vegetables investigated were cranberries, peaches, blueberries, kiwi, carrots, tomatoes, potatoes, lettuce, and grapefmit juice. The purpose of including an account of this work is to illustrate why HPLC/MS/MS is the method of choice for residue work at the 1.0 ng g level, especially for difficult matrices. 

Gel permeation chromatography with UV detection at 285 nm was used for the determination of alkylenebis(dithiocarbamates) containing the original alkylenebis-(dithiocarbamate) moiety on tomatoes and lettuce treated with maneb and zineb. 

Plants (rice, potato, cabbage, lettuce, soybean, pear, cucumber, tomato, eggplant, ornamentals), soil and water Gas-chromatographic determination [with mass spectrometry (MS) or flame thermionic detection (FTD)] for plant materials, soil and water... 

Apricots, apples, grapes, Japanese pears, melons, peaches, strawberries, tomatoes, watermelons and soil Gas-chromatographic determination for all materials... 

Plants (cucumber, tomato, eggplant, French bean, deep root leek, strawberry, grape, apple, pear, cherry, peach, Unshu orange, Chinese citron, watermelon, persimmon, lemon, kabosu lime, sudachi, small beans and kidney beans), soil and water Gas-chromatographic determination... 

B Gas chromatography/mass spectrometry (GC/MS) method (for plants) is used to determine buprofezin in cucumber, pepper, tomato, squash and eggplant. ... 

The responses of the test seed to increased external osmolarity were determined by germinating the seeds in a polyethylene glycol (PEG) solution of 40.3 mOsm (10). The only test seeds significantly affected by this treatment were those of tomato where PEG-treated seed germination was 69.3% of that observed in deionized water. Dilution of the aqueous extract to 1 32 (w/w) removed all inhibitory action, but the diluted solution increased wheat germination. 

Assessments of risks associated with the use of chlorpyrifos insecticide products for workers have been made. The assessments are based on the results of field studies conducted in citrus groves, a Christmas tree farm, cauliflower and tomato fields, and greenhouses that utilized both passive dosimetry and biomonitoring techniques to determine exposure. The biomonitoring results likely provide the best estimate of absorbed dose of chlorpyrifos, and these have been compared to the acute and chronic no observed effect levels (NOELs) for chlorpyrifos. Standard margin-of-exposure (MOE) calculations using the geometric mean of the data are performed however, probability (Student s f-test) and distributional (Monte Carlo simulation) analyses are deemed to provide more realistic evaluations of exposure and risk to the exposed population. 

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