Assessing bias in total mercury results after removing a subsample from the bottle

U.S. EPA Method 1631 for total mercury (THg) analysis in water recommends that bromine monochloride (BrCl) be added to the original bottle in which the sample was collected, to draw into solution any Hg that may have adsorbed to the bottle walls. The method also allows for the removal of a subsample of water from the sample bottle for methylmercury (MeHg) analysis prior to adding BrCl. We have demonstrated that the removal of a subsample from the sample bottle prior to THg analysis can result in a positive concentration bias. The proposed mechanism for the bias is that ‘excess’ inorganic Hg, derived from the subsample that was removed from the bottle, adsorbs to the bottle walls and is then drawn into solution when BrCl is added. To test for this bias, we conducted an interlaboratory comparison study in which nine laboratories analysed water samples in fluorinated polyethylene (FLPE) bottles for THg after removing a subsample from the sample bottle, and analysed a replicate sample bottle from which no subsample was removed. We received seven complete data sets, or 63 unique sample pairs. The positive concentration bias between the bottles was significant when comparing all samples in aggregate (1.76 ± 0.53 ng/L after subsample removal, 1.57 ± 0.58 ng/L with no subsample removal, P < 0.05), however when comparing each of the three samples individually, the only significant bias was in the saline sample (Site UJ; 1.51 ± 0.31 ng/L after subsample removal, 1.32 ± 0.47 ng/L with no subsample removal, P < 0.05). Based on the findings presented here, we conclude that water chemistry, volume of water poured off, and the sample storage temperature explain some but not all of the observed bias, and we recommend collecting THg and MeHg samples in separate bottles whenever possible.     

Solvothermal Synthesis,Crystal Structure and Properties of the First Organic‐templated Holmium Sulfate [C2N2H10]3[Ho2(SO4)6·2H2O]

The first organic amine‐templated holmium sulfate [C₂N₂H₁₀]₃[Ho₂(SO₄)₆·2H₂O] ( 1 ) has been synthesized solvothermally and has been structurally characterized by single‐crystal X‐ray diffraction studies, IR spectroscopic, thermogravimetric (TG) and inductivity coupled plasma (ICP) measurements. Crystal analyses of compound 1 showed a novel inorganic layer constructed from the zigzag and helical [–Ho–O–S–O–]_n chains, both of the chains are connected by μ‐2 SO₄^2– groups to form 10‐membered rings. The solvent plays an important role during the formation of 1 .     

Thermochemical Study of Coordination of Holmium Chloride Hydrate with Diethylammonium Diethyldithiocarbamate

The complex of holmium chloride hydrate with diethylammonium diethyldithiocarbamate (D-DDC) was synthesized via mixing their solutions in absolute alcohol under a dry N2 atmosphere. The elemental and chemical analyses show that the complex has the general formula Et2NH2[Ho(S2CNEt2)4]. It was also characterized by IR spectroscopy. The enthalpies of the dissolution of holmium chloride hydrate and D-DDC in absolute alcohol at 298.15 K o and the enthalpy changes of liquid-phase reactions of the formation of Et2NH2[Ho(S2CNEt2)4] at different temperatures were determined by microcalorimetry. On the basis of experimental and calculated results, three thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), the rate constant and three kinetic parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of the liquid-phase reaction of the complex formation were obtained, The enthalpy change of the solid-phase complex formation reaction at 298.15 K was calculated by means of a thermochemical cycle.     

Characterization and Crystal Structure of a New Holmium(Ⅲ) Complex with the Macrocyclic Ligand Derived from 2,6-Dfformyl-4-methylphenol and Diethylenetriamine

The title compound (13,27-dimethyl-3,6,9,17,20,23-hexaazatricyclo-[23.3.1.111,15]-triaconta- 1 (29),2,9,11,13,15(30), 16,23,25,27-decaene-29,30-diol-N3,N6,N9,O29,O30)-bis(nitrato-O,O')-holmium(Ⅲ) nitrate hydrate has been prepared and characterized by elemental analysis, infrared spectra, and electrospray mass spectra. Its crystal and molecular structures were determined by X-ray diffraction methods. The crystal crystallizes in the monoclinic system, space group C2/c with a = 23.737(12), b = 14.237(7), c = 19.801(10) (A), β = 91.36(1)°, Mr = 831.57, V = 6690(6) (A)3, Z = 8,Dc = 1.651 g/cma, F(000) = 3344, R = 0.0482 and wR = 0.0923. The holmium ion is located in one of the compartments of the macrocyclic ligand and presents a distorted tricapped trigonal prismatic coordination geometry. The macrocycle is coordinated with two oxygen and three nitrogen atoms.Two nitrates are chelated in the opposite positions of the macrocycle, and the third one is ionic.     

Ternäre Chloride in den Systemen NaCl/HoCl3 und NaCl/ErCl3

Ternary Chlorides in the Systems NaCl/HoCl₃ and NaCl/ErCl₃ Phase diagrams of the systems NaCl/HoCl₃ and NaCl/ErCl₃ were determined by means of DTA and high-temperature XRD. There exist compounds Na₃LnCl₆, NaLnCl₄ (Ln ? Ho, Er) and NaHo₂Cl₇. NaHoCl₄ undergoes a phase transition at 374°C from the NaGdCl_4? to the NaErCl_4? type of structure. The thermodynamic functions for the formation of the compounds from NaCl and LnCl₃ were determined by solution calorimetry and e.m.f. measurements in galvanic cells for solid electrolytes. The compounds NaLnCl₄ are the most stable ones.     

Synthesis and reactivity against Cp2TiCl of 4-isoprenyl-β-lactams. Trapping of N-titanoimidoyl radicals from cyanoformyl-2-azetidinones

A Staudinger reaction between methoxyketene and two different imines formed from citral afforded, after chemical transformation, the (E/Z)-4-alkenylepoxy-2-azetidinones 2, 3 and 4. These compounds, by reaction with Cp₂TiCl, did not cyclize to afford the expected polycyclic β-lactams, but the corresponding allylic alcohols 12, 13 and 15 were obtained instead. Unexpectedly, the treatment of cyanoepoxide (E)-3 with Cp₂TiCl also gave the hydroxyl aldehyde (E)-14 whose formation suggests to us that a possible radical reduction of the cyano group might have occurred, and we lastly succeeded in the capture of the N-titanoimidoyl radicals. The behaviour observed for the isoprenoid side chain in the Staudinger reaction, the reactions with Cp₂TiCl, as well as the trapping of N-titanoimidoyl radicals generated from benzocyanoformyl-2-azetidinones with the Ti(III) reagent, are discussed.     

一氯二茂钛在有机合成中的应用研究

综述了近年来一氯二茂钛在有机合成中的应用研究, 主要涉及环氧化物的还原开环、其它还原反应、Reformatsky反应、呐醇偶联反应、不饱和金属卡宾与自由基的加成反应、制备烯糖化合物的反应、制备C-苷的反应等.     

Direct iodination of 3- and 4-nitropyrazoles with a reagent based on iodine monochloride and silver sulfate

The reagent obtained from iodine monochloride and silver sulfate in sulfuric acid easily iodinates I-methyl-3-nitropyrazole under mild conditions to give 4-iodo or 4,5-diiodo derivatives, 1-Methyl-4-nitropyrazole was also directly iodinated with this reagent for the first time. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1482–1484, August, 2000.     

Solvothermal Synthesis,Crystal Structure,and Properties of a New Organic‐Templated Holmium Sulfate with 1D Single Ladder Chains

A new organic amine templated 1D holmium sulfate (C₂H₈N)[Ho(SO₄)₂ · H₂O] ( 1 ) has been synthesized and solvothermally and structurally characterized by single‐crystal X‐ray diffraction, IR spectroscopy, thermogravimetric and X‐ray diffraction analyses as well as scanning electron microscopy (SEM). The structure of framework 1 is constructed from HoO₈ polyhedra and SO₄ tetrahedra. S(1) and S(2) connects Ho(1) and its crystallographic partners by using three S–O–Ho linkages to generate double chains, whereas the adjacent double chain are connected by μ₃‐O (O₅) atoms to form a novel single ladder chains.     

Complex formation studies on Ho(III) and Lu(III) with 1-(2-pyridylazo)-2-naphthol (PAN) in alcohol-water solutions

The formation ofPAN complexes in the systemsLn(III)—PAN—alcohol-water (where:Ln(III)=Ho, Lu and alcohol=ethanol,n-propanol,iso-propanol) was investigated by a spectrophotometric method. Equilibrium constants for the reactionLn ³⁺ + HLLnL ²⁺ + H⁺ (HL=PAN) and stability constants of complexesLnL ²⁺ were calculated.

---

Untersuchungen zur Komplexbildung von Ho(III) und Lu(III) mit 1-(2-Pyridylazo)-2-naphthol (PAN) in alkoholisch-;wä\rigen Lösungen

Zusammenfassung Die Bildung der Komplexe vonPAN in den SystemenLn(III)—PAN—Alkohol-Wasser (Ln(III)=Ho, Lu; Alkohol=Ethanol,n-Propanol,iso-Propanol) wurde mit einer spektrophotometrischen Methode untersucht. Die Gleichgewichtskonstanten der ReaktionenLn ³⁺ + HLLnL ²⁺ + H⁺ (HL==PAN) und die Stabilitätskonstanten der KomplexeLnL ²⁺ wurden berechnet.