Fullerene‐Crown Ether Coated Piezoelectric Crystal Liquid Chromatographic Detector for Metal Ions and Polar/Nonpolar Organic Molecules

Fullerene(C60)‐dibenzo‐16‐crown‐5‐oxyacetic acid (DBI6C5‐OCH₂‐COOC₆₀) was prepared and applied as the coating material on piezoelectric quartz crystals for detection of various metal ions and polar/nonpolar organic molecules. The C60‐crown ether‐coated piezoelectric crystal sensor with a home‐made computer interface for signal acquisition and data processing was applied as an ion chromatographic (IC) detector for various metal ions, e.g., alkali metal, alkaline earth metal and transition‐metal ions. The piezoelectric detector exhibited quite good sensitivity of 10⁴ ～ 10⁶ Hz/M and good detection limit of 10^?3 ～ 10^?4 M for these metal ions. The C60‐crown ether piezoelectric detector compared well with the commercial conductivity detector conventionally used for metal ions. The ionic size and ionic charge seemed to have significant effect on the frequency response of the piezoelectric detector. The C60‐crown ether coated piezoelectric crystal sensor was also employed as a high performance liquid chromatographic (HPLC) detector for various polar organic molecules with frequency responses in the order: amines > carboxylic acids > alcohols > ketones. Furthermore, nonpolar organic molecules, e.g., n‐hexane, 1‐hexene and 1‐hexyne, were also detected with this piezoelectric crystal detector. The frequency responses of the piezoelectric crystal detector for these nonpolar organic molecules were in the following order: alkynes > alkenes > alkanes. The effects of solvents and flow rate on the frequency responses of the piezoelectric crystal detector were investigated. The C60‐crown ether coated piezoelectric crystal detector also showed short response time (< 1 min.) and good reproducibility.     

Piezoelectric Crystal Membrane Chemical Sensors Based on Fullerene and Macrocyclic Polyethers

Various reusable and sensitive piezoelectric (PZ) quartz crystal membrane sensors with home‐made computer interfaces for signal acquisition and data processing were developed to detect organic/inorganic vapors and organic/inorganic/biologic species in solutions, respectively. Fullerene(C60), fullerene derivatives and artificial macrocyclic polyethers, e.g., crown ethers and cryptands, were synthesized and applied as coating materials on quartz crystals of the PZ crystal sensors. The oscillating frequency of the quartz crystal decreased due to the adsorption of organic or inorganic species onto coating material molecules on the crystal surface. The crown ether‐coated PZ crystal gas detector exhibited high sensitivity with a frequency shift range of 10–340 Hz/(mg/L) for polar organic gases, a short response time (< 2.0 min.), good selectivity, and good reproducibility. The Ag(I)/crptand22 and Ru(III) / crptand22 coated PZ gas detectors were also prepared for nonpolar organic vapors, e.g., alkynes and alkenes. The frequency shifts of the nonpolar PZ sensors were in the order: alkynes > alkenes > alkanes. A Ti(IV)/Cryptand22‐coated PZ crystal sensor was also developed to detect the inorganic air pollutants, e.g., CO and NO₂. A piezoelectric gas sensor for both polar/nonpolar organic vapors based on C60‐cryptand22 was also prepared. The cryptand22‐coated PZ gas sensor was also employed as a GC detector for organic molecules. The cryptand22‐coated piezoelectric GC detectors compared well with the commercial thermal conductivity detector (TCD). The interaction between fullerene C60 and organic molecules was studied with a fullerene coated PZ gas detector. A multi‐channel PZ organic gas detector with PCA(Principal Component Analysis) and BPN (Back Propagation Neural) analysis methods was developed. Various liquid piezoelectric crystal sensors based on long‐chain macrocyclic polyethers, e.g., C₁₀H₂₁‐dibenzo‐16‐crown‐5, C₁₈H₃₇‐benzo‐15‐crown‐5, (C₁₇CO)₂‐cyptand22 and fullerene derivatives, e.g., C60‐NH‐cryptand22 and dibenzo‐16‐crown‐5‐C60, were also developed as HPLC detectors for metal ions, anions, and various organic compounds in solutions. The sensitive and highly selective PZ bio‐sensors based on enzymes, polyvinylaldehyde, polycinnaldehyde‐C60 and C60‐cryptand22 were developed to detect various biologic species, e.g., proteins, glucose, and urea. A quite sensitive EQCM (Electrochemical Quartz Crystal Micro‐balance) detection system was also developed for detection of trace heavy metal ions.     

Polymer Coated Piezoelectric Quartz Crystal Protein Bio‐Sensors

A polymer coated piezoelectric crystal detection system with a home‐made computer interface for signal acquisition and data processing was prepared as a liquid chromatographic detector for various proteins. Various polymers, e.g., polyvinyl aldehhyde (polyacrolein) (PVA), polyacrylamide/glutaldehyde (PAA/GA) and bio‐gel A, were used as coating materials on quartz crystals for adsorption of various protein molecules, e.g., catalase (CA), hemoglobin (Hb), α‐chymotrypsin (Ch), albumin (Ab). The frequency responses of the polyacrlein coated piezoelectric detector for various proteins were in the order: catalase> hemoglobin> α‐chymotrypsin > albumin. In contrast, the order of the frequency responses of bio‐gel A and polyacrylamide/glutaldehyde coated piezoelectric crystals for these proteins were: hemoglobin> catalase > α‐chymotrypsin ≥ albumin and hemoglobin > albumin > catalase. The polyacrolein coated piezoelectric crystal protein detector exhibited a good linear frequency response with a high sensitivity of about 2.5×10³ Hz/(mg/mL) for catalase. In addition, bio‐gel A and polyacrylamide/glutaraldehyde coated crystals were sensitive to hemoglobin with sensitivities of about 4.5×10³ Hz/(mg/mL) and 3.0×10³ Hz/(mg/mL), respectively. Study of the interference of various organic molecules, e.g., alcohols, amines, ketones and carboxylic acids, in the detection of proteins with theses polymer coated crystals was also made. The polyacrolein coated crystal for proteins under went less interference from various organic molecules than bio‐gel A or polyacrylamide/glutaraldehyde coated crystals. Effects of coating load, concentration of proteins and flow rate of liquid chromatographic eluent were also investigated and discussed.     

Piezoelectric Crystal Liquid Flow Detection Systems Based on Alkyl (C18)‐Benzo‐15‐Crown 5 for Organic Compounds and Metal Ions

A water in soluble long‐chain crown ether alkyl (C18)‐benzo‐15‐crown‐5 was synthesized and applied as a coating material on quartz crystal membranes of a liquid flow piezo electric crystal sensor. The oscillating crown ether‐coated piezo electric (PZ) crystal with a home‐made computer inter face was prepared as a liquid chromato graphic (LC) detector for organic species and metal ions in aqueous solutions. The oscillating frequency of the quartz crystal decreased due to the adsorption of organic molecules or metal ions on crown ether molecules. Effects of functional group, molar mass, steric hindrance, and polarity of organic molecules on frequency responses of the crown ether coated PZ crystal detector were investigated. The frequency responses of the crown ether coated PZ crystal detector for various molecules were in the order: amines > carboxylic acids > alcohols > ketones. The crown ether PZ detector also exhibited good sensitivity for some heavy metal ions and the frequency shifts were in the order: Cr³⁺ » Pb²⁺ > Co²⁺ > Cd²⁺ > Ni²⁺ > Cu²⁺. The crown ether coated piezo electric crystal LC detector demonstrated low detection limits for various polar organic molecules, e.g., 6.0 × 10^?5 M for propylamine, and metal ions, e.g., 2.9 × 10^?5 M (1.8 ppm) for Cu²⁺; the crown ether PZ detector also gave good reproducibility when re used. A quite sensitive electrochemical quartz crystal microbalance (EQCM) detection system was also set‐up for detecting trace heavy metal ions in solutions. The variation in frequency of the PZ crystal and the diffusion current were observed simultaneously after the reduction in heavy metal ions such as Cu²⁺ and Ni²⁺. The EQCM detection system exhibited fairly good sensitivity, e.g., 112 Hz/ppm for Cu²⁺ and a good detection limit, e.g., 0.13 ppm for Cu²⁺ ions. Comparison between EQCM and PZ detection systems was made and discussed.     

Supramolecular Assemblies of Three New Metronidazole Derivatives Constructed with Various Dihydroxy-benzoic Acids via Hydrogen Bonds

Metronidazole(MTZ) is an important antibiotic, which has been widely applied to cure protozoal and bacterial diseases for human beings or animals. Herein, three novel drug supramolecular crystals constructed by MTZ with 2,5-dihydroxy-benzoic acid(2,5-DHBA)(1), 2,6-dihydroxy-benzoic acid(2,6-DHBA)(2) and 3,5-dihydroxy-benzoic acid(3,5-DHBA)(3), respectively, have been discovered. The hydrogen bonds of N-H···O(O-H···N), C-H···O and O-H···O play important roles in the 3D supramolecular framework formation for crystals 1-3. Interestingly, due to the vary locations of the substituent groups, the two-dimensional layers in crystals 1 or 2 are constructed via intermolecular hydrogen bonds between MTZ and 2,5-DHBA or 2,6-DHBA, while in crystal 3 water molecules play a significant role except the intermolecular hydrogen bonds between MTZ and 3,5-DHBA. In addition, five synthons of I R₂²(8), II R₃³(9) in crystal 1, III R₁²(4), IV R₂²(8) in crystal 2 and V R₂²(7) in crystal 3 formed through various hydrogen bonds are founded in this work. Systematic studies of syntheses, crystal structures and thermal analysis are reported.     

A theoretical study of amines adsorption in HMOR by using ONIOM2 method

The two-layered ONIOM method is used to study the interaction of amines (NH₃, MeNH₂, Me₂NH and Me₃N) with H-type mordenite (HMOR). For all the calculations, the high-layer is described by the B3LYP/6-31G(d,p) method, while the HF/3-21G method is used for the low-layer. In the adsorption complexes, proton transfer from the HMOR framework to amines is observed, and the protonated amines (R₃NH⁺) are stabilized by hydrogen bonding between the negatively charged zeolite framework and the N---H bonds. The strength of the OH---N hydrogen bonding is reflected by differences in the N---H stretching frequency of R₃NH⁺ between the adsorbed state and the gas phase. The relative order of the amine basicity on the basis of the computed adsorption energies agrees well with the experiments, but differs from those in the gas phase (proton affinity) and in solvents (pK_a).     

Evaluation of stationary phases and gas chromatographic detectors for determination of amines in water

For the first time, a systematic overview deals with the advantages and disadvantages of several stationary phases (polar and non‐polar) and gas chromatographic detectors (flame ionization detector, nitrogen–phosphorus detector and MS) for the determination of 27 amines (aliphatic and aromatic amines and N‐nitrosamines) in water samples. To increase sensitivity (250 mL of sample was eluted with 150 μL of solvent) and matrix elimination, an automatic SPE system was employed prior to GC determination. The best results in terms of resolution and retention times were achieved using a column coated with 5% phenyl‐dimethylpolysiloxane (DB‐5). Capacity factor (k) values for the 27 amines increased with the rise in the polarity of the stationary phase, ranging from 3.0–27.7 and 2.2–14.4 for polar (polyethylene glycol) and non‐polar (DB‐5) columns, respectively. The detection limits of the method were 0.9–9 μg/L for flame ionization detector, 8–95 ng/L for nitrogen–phosphorus detector and 0.2–6.3 ng/L for MS. The precision was similar for the three detectors (RSD, 3.7–6.0%). The GC‐MS method was applied with a high degree of accuracy and precision to determine amines in real samples including tap, river, pond, well, swimming pool and wastewaters.     

Conformational analysis of some acrylates using dipole moment calculations by CNDO/force method

CNDO MO calculations are carried out for four acrylates, H₂C=C (R₁)-COO (R₂) with R₁=H, Me and R₂=Me, Et for dipole moment determination using the Pople-Segal expression.⁷ Energy minimization for various conformers in each molecular system was achieved by the gradient method. Dipole moments for comparatively stable conformers of each of the molecules considered are reported. Theoretically calculated energy values are used to arrive at the equilibrium geometry and the corresponding dipole moments are compared with the experimental values in each system considered.     

Applications of Macrocyclic Polyethers in Analytical Sensors and Ion Separation

Artificial macrocyclic polyethers were synthesized and applied as neutral carriers for ion-selective PVC membrane electrodes, ion-chromatographic packing materials, extractants and adsorbents for ion separation, coating materials for piezoeletrical membrane sensors for organic species, and ion-transport carriers through liquid membranes. Ion-selective electrodes such as those for K⁺ Na⁺, UO₂²⁺, Cs⁺, Pb²⁺, Fe³⁺, Hg²⁺ and Ag⁺ ions based on crown ether-phosphotungstic acid (PW) precipitates and dithio crown ethers respectively were prepared and showed good sensitivity and selectivity. Crown ether-PW precipitates were applied as adsorbents of rare-earth ions and some common heavy-metal ions. Some rare-earth ions were easily extracted with crown ethers, especially 15-crown-5. Poly(stytene/divinyl benzene) cryptand-22 resin was synthesized and applied as a bifunctional stationary phase of ion chromatography to separate bom cations and anions, even some organic carboxylate geometric isomers. Crown ethers such as mono-benzo-15-crown-5 was successfully applied as a coating material on piezoelectric quartz membrane sensors for some organic species. The oscillation frequency of the crown-ether quartz-membrane sensor was sensitive to organic vapours such as amines and alcohols. Upon adsorption of organic species on the crown-ether quartz membrane, the oscillation frequency of the sensor decreased obviously. Special crown ether such as dibenzo-16-crown-5-oxyacetic acid, decyl-cryptand-22 and 1, 4-dihydro-pyridine-18-crown-5 were synthesized and successfully applied as ion-transport carriers (ionophores) for transport of Na⁺ K⁺ and Mg²⁺ ions through liquid membranes.     

Separation of acetylated amino acids

Acetylated amino acids (Nac-AA) are separated as anions on a reversed stationary phase from a mobile phase containing a quaternary ammonium (R₄N⁺) salt as a mobile phase additive. If the counteranion accompanying the R₄N⁺ or ionic strength salt is detector active than the separated NAc-AA derivatives can be detected by an indirect detection strategy. Variables influencing the separations are NAc-AA side chain structure and the mobile phase parameters such as hdyrophobicity of the alkyl groups in the R₄N⁺ salt, R₄N⁺ salt concentration, counteranion eluent strength, counteranion concentration, solvent composition, and pH. Indirect detection is influenced by these same mobile phase parameters as well as the properties of the detector active counteranion. The detection limit for indirect photometric detection at 287 nm using a tetrapentylammonium salt with a disodium 1,5-naphthalenedisulfonate—sodium benzoate counteranion mixture was about 70 pmol of NAc-AA depending on the amino acid injected as a 10-μ1 sample.     

阳离子寡肽序列的合成及生物学研究——推荐一个针对化学生物学专业学生的研究型实验

采用多肽固相合成技术制备了寡肽序列RRRRRRRR(R8)。通过电喷雾电离质谱仪对序列的相对分子质量进行了表征。进一步通过琼脂糖凝胶电泳和细胞内吞实验考察寡肽序列在生物学研究方面的应用。本实验可以加深学生对有机化学、高分子化学及生物化学的理解与运用,培养学生分析问题和解决问题的综合能力。     

Study of the responses of a gas chromatography—reduction gas detector system to gaseous hydrocarbons under different conditions

The response of a reduction gas detector (RGD) to C₂-C₆ alkenes, C₂-C₆ alkanes, isoprene and benzene has been investigated using gas chromatography (GC) with a packed column. The RGD is considerably more sensitive to alkenes than is the flame ionization detector. The detection limit of this present GC/RGD system for alkenes is about 0.01 ng. It has much greater sensitivity to alkenes than to alkanes. Its sensitivity increases with increasing HgO bed temperature, but its selectivity towards alkenes decreases at the same time. The selectivity of the RGD may not be significant for much heavier molecules. The sensitivity of the RGD is inversely proportional to the carrier gas flow rate through the HgO bed. The baseline of the system increases significantly with increasing oven temperature.     

A piezoelectric quartz crystal sensor array self assembled calixarene bilayers for detection of volatile organic amine in gas

P-tert-butylcalix[n]arenes (n=4, 6, 8, abbreviated as CA[4], CA[6], CA[8], respectively) were immobilized on the Au surface of the piezoelectric quartz crystal by the reaction between CA[n] and the acid chloride terminated mercaptoacetic acid (MAA) self assembled monolayers to form MAA/CA[n] bilayers. The sensing films were not only immobilized easily and reproducibly, but also used to improve the reversibility of the sensor signal. The response characteristics show the response of CA to organic amine attributes to specific interaction between CA[n] (host) and organic amines (guest). The frequency shifts of n-butylamine and iso-butylamine are much larger than tert-butylamine and diethylamine because of shape-selection and hydrogen bonding. Compared to CA[6] and CA[4], CA[8] has highest sensitivity to organic amine due to having more flexibility to accommodate guest molecules. A sensor array with three-layer back-propagation neural network was applied to detect the binary mixture of n-butylamine in the range of 7.14–142 μl l⁻¹ and iso-butylamine in the range of 7.14–57 μl l⁻¹. The optimum values of learning rate (0.15) and momentum term (0.8) were determined by experiment. The best epoch of training was 1098. The root mean square error of prediction was 1.69 (μl l⁻¹) for n-butylamine, and 1.42 (μl l⁻¹) for iso-butylamine.     

Extraction de l'acide silicomolybdique par le nitrate de triisooctylamine en milieu dichloro-1,2-ethane Nature des équilibres and application analytique

-Molybdosilicic acid () in aqueous solution is extracted by triisooctylamine nitrate (R₃NHNO₃) in dichloro-l,2-ethane (S) according to an equilibrium which involves the dissociation of the extracted species in the organic phase: _aq+4(R₃NHNO₃)_s [(R₃NH)₃]_s^-+(R₃NH)_s⁺+4(N0₃^-)_aq+xH⁺ Extraction allows separation of from the excess of molybdenum necessary for its quantitative formation from silicate and molybdate. The direct spectrophotometric determination of the heteropolyacid in the organic phase is simple and sensitive ( =28000 1 cm^-1 mole^-1 at 300 nm).

Zusammenfassung

-Molybdatokieselsäure () in wässriger Lösung wird durch Triisooctylaminnitrat (R₃NHNO₃) in 1,2-Dichlorän (S) entsprechend einem Gleichgewicht extrahiert, in dem die Dissoziation der extrahierten Spezies in der organischen Phase enthalten ist: _aq+4(R₃NHNO₃)_s [(R₃NH)₃]_s^-+(R₃NH)_s⁺+4(N0₃^-)_aq+_xH⁺ Die Extraktion erlaubt die Trennung von vom Molybdän-Überschuss, der für die quantitative Bildung von aus Silicat und Molybdat notwendig ist. Die direkte spektrophotometrische Bestimmung der Heteropolysäure in der organischen Phase ist einfach und empfindlich ( = 28000 l cm^-1 mol^-1 bei 300 nm).     

A Piezoelectric crystal detector for continuous monitoring of water evolved during thermal decomposition reactions

A method for the continuous monitoring of water vapour evolved during thermal decomposition reactions is developed based on the reversible adsorption of water on a bare piezoelectric crystal with nickel electrodes. Gaseous decomposition products formed in the furnace chamber of the thermoanalytical equipment are collected and transported to the detector cell by the carrier gas. A linear relationship exists between the decrease in vibrational frequency of the crystal and the concentration of water in the carrier gas up to 900 mug/l. H(2)O [1200 ppm (v/v)]. The signal curve of the piezoelectric water monitor can be recorded simultaneously along with the TG, DTG and DTA curves and used to identify the decomposition step(s) in which water was formed. CO, CO(2) and low molecular weight hydrocarbons do not interfere. Condensable organic crack products can be removed by a suitable pretrap.     

Pseudoelementverbindungen IX. Organostannylierung von Cyanamidonitrat — Molekül- und Kristallstruktur von N-Trimethylstannyl-N′-nitro-carbodiimid

Considered under the aspect of its ambidence, the reactivity of cyanamidonitrate [NO₂NCN]⁻ towards triorganostannyl chlorides was investigated. The reaction products of type R₃Sn-NCN-NO₂ were characterized by ¹H-NMR, ¹³C-NMR, ¹¹⁹Sn-NMR and IR spectroscopy. While cyanamides of the type [R_nE(Y)NCN]⁻ (R_nE(Y) = RC(O), RC(NCN), R₂ P(O), R₂P(S), R₂P(NCN), RSO₂) are coordinated exclusively either via the terminal nitrogen (monodentately) or via both the nitrile group end on and the chalcogen atom (bidentately), we found N-triorganostannyl-N′-nitro-carbodiimides as the first example in which the NCN group acts as a bidentate bridge with metal-N bonds in 1- and 3-position. For Me₃Sn-NCN-NO₂ the crystal structure was determined.

Zusammenfassung

Unter dem Aspekt der Ambidenz wurde die Reaktivität von Cyanamidonitrat [NO₂NCN]⁻ gegenüber Triorganostannylchloriden untersucht. Die Reaktionsprodukte des Typs R₃Sn-NCN-NO₂ wurden ¹H-NMR-, ¹³C-NMR-, ¹¹⁹Sn-NMR- sowie IR-spektroskopisch charakterisiert. Während Cyanamide des Typs [R_nE(Y)NCN]⁻ (R_nE(Y) = RC(O), RC(NCN), R₂P(O), R₂P(S), R₂P(NCN), RSO₂) ausschlieβlich über das terminale Stickstoff- (einzähnig) bzw. über das Nitrilstickstoff- und das Chalkogenatom (zweizähnig) gebunden werden, fanden wir mit N-Triorganostannyl-N′-nitro-carbodiimiden erstmalig Beispiele, in denen die NCN-Gruppe zweizähnig verbrückend in 1- und 3-Position koordiniert wird. Für Me₃Sn-NCN-NO₂ liegt eine Kristallstrukturbestimmung vor.     

取代基对木质素三聚体模型化合物醚键均裂反应影响的密度泛函理论研究

利用密度泛函理论M062X/6-31++G(d,p)方法,对27种具有不同取代基(甲基、羟甲基和甲氧基)的木质素三聚体模型化合物的Cα-O和Cβ-O键均裂解离能进行了理论计算,探究了不同位置取代基对醚键解离能的影响规律。结果表明,当R2或R3位氢原子仅有一个被甲氧基取代时,Cβ-O键解离能变化很小;当R2、R3位氢原子均被甲氧基取代时,Cβ-O键解离能明显降低;且R4、R5位甲氧基能强化R2、R3位甲氧基对Cβ-O键解离能的降低程度,而不受R1位取代基的影响。当R4、R5位氢原子相继被甲氧基取代时,Cα-O键解离能逐渐降低,且R2、R3位甲氧基也能强化R4、R5位甲氧基对Cα-O键解离能的降低程度。当R1位氢原子相继被甲基、羟甲基取代时,Cα-O键解离能逐渐升高,然而R2、R3位甲氧基会弱化R1位甲基、羟甲基对Cα-O键解离能的升高程度;R1位甲基不会影响Cβ-O键解离能,羟甲基却能明显提高Cβ-O键解离能。     

One-step synthesis of vinyl carbamates catalyzed by mononuclear ruthenium complexes via addition of carbon dioxide and amine to terminal alkynes

Terminal alkynes with secondary amines (dimethylamine, diethylamine, piperidine, morpholine) and CO₂ in the presence of mononuclear ruthenium catalysts, afford the vinyl carbamates R₁CH=CH---O---CONR₂. The reaction studies suggest, as the active catalytic species, a ruthenium-vinylidene intermediate.     

Stereochemistry of the Heterocyclic Alcohols Containing Piperidine Unit

The stereochemistry of the heterocyclic alcohols (R₁-OH~R₄-OH,see Fig.1) containing piperidine unit has been studied on the basis of the calculations of molecular mechanics and quantum chemistry. The calculations of alcohols (R₁-OH~R₄-OH) and their carboxylate derivatives were carried out, and the results of these calculations were listed in Tab.1 and Tab.2. It was showed that there existed the non-classical orbital super-conjugated interactions between the nitrogen atom and oxygen atom which caused the conformations to be more stable when the hydroxylic group lay at axial than at equatorial with respect to the piperidine ring in compounds (R₁-OH) and (R₃-OH). If the axial hydrogen atoms at C₂ and C₆ positions in the piperidine ring were substituted, or the molecular existed in the polar solutions, this non-classical orbital super-conjugated interactions would be much weak even diminished. In this case,the conformations were more stable when the hydroxylic group at equatorial than at axial in these compounds. These consistented with the experimental results.     

酸量法测定四氢硼酸和八氢三硼酸季铵盐和碱金属盐

鉴定有机硼化合物,往往要测定元素硼的含量。用氧瓶燃烧分解法测定有机硼最为简便迅速,但由于有碳化硼的形成,常常导致元素分析值的偏低;用此法只能分解很少量样品,且不能完全燃烧^[1]。同时有机硼化合物中Fe、Co、Ni、Zn、Cu、Cr、Mn等金属元素的存在,常常对容量法或比色法测定硼有干扰。