Click‐Conjugation of Nanogold‐Functionalized PAMAM Dendrimer: Toward a Novel Electrochemical Detection Platform

This work reports a new electrochemical monitoring platform for sensitive detection of Cu²⁺ coupling click chemistry with nanogold‐functionalized PAMAM dendrimer (AuNP‐PAMAM). The system involved an alkyne‐modified carbon electrode and an azide‐functionalized AuNP‐PAMAM. Initially, the added Cu²⁺ was reduced to Cu⁺ by the ascorbate, and then the azide‐modified AuNP‐PAMAM was covalently conjugated to the electrode via Cu⁺‐catalyzed azide‐alkyne click reaction. The carried AuNPs accompanying PAMAM dendrimer could be directly monitored by stripping voltammetry after acidic pretreatment. By introduction of high‐loading PAMAM dendrimer with gold nanoparticles, as low as 2.8 pM Cu²⁺ (ppt) could be detected, which was 125‐fold lower than that of gold nanoparticle‐based labeling strategy. The method exhibited high specificity toward target Cu²⁺ against other potentially interfering ions, and was applicable for monitoring Cu²⁺ in drinking water with satisfactory results.     

Nanoparticle‐Driven Orientation Transition and Soft‐Shear Alignment in Diblock Copolymer Films via Dynamic Thermal Gradient Field

Sharp dynamic thermal gradient (∇T ≈ 45 °C mm⁻¹) field‐driven assembly of cylinder‐forming block copolymer (c‐BCP) films filled with PS‐coated gold nanoparticles (AuNPs; d_NP ≈ 3.6 nm, φ_NP ≈ 0–0.1) is studied. The influence of increasing AuNP loading fraction on dispersion and assembly of AuNPs within c‐BCP (PS‐PMMA) films is investigated via both static and dynamic thermal gradient fields. With φ_NP increasing, a sharp transition from vertical to random in‐plane horizontal cylinder orientation is observed due to enrichment of AuNPs at the substrate side and favorable interaction of PMMA chains with gold cores. Furthermore, a detachable capping elastomer layer can self‐align these random oriented PMMA microdomains into unidirectional hybrid AuNP/c‐BCP nanolines, quantified with an alignment order parameter, S.

     

Acetonitrile-dependent oxyphosphorylation: A mild one-pot synthesis of β-ketophosphonates from alkenyl acids or alkenes

An efficient one-pot synthesis of β-ketophosphonates has been developed, via the reaction of α,β-alkenyl carboxylic acids or alkenes with H-phosphonates and air oxygen, catalyzed by CuSO₄·5H₂O in CH₃CN. CH₃CN plays a decisive role, probably by forming an active oxygen complex [(MeCN)_nCu^II-O-O·].     

An infrared study on Langmuir–Blodgett films of octadecylammonium octadecanoate: FWHM and the vibrational coupling

The monolayer of the mixture of octadecanoic acid and octadecylamine with molar ratio 1:1 has been investigated at the air–water interface. It was found that the monolayer shows a rather stable state at the surface pressure of 30 mN/m and this monolayer can be transferred onto a CaF₂ plate by Langmuir–Blodgett (LB) technique. The infrared spectra of LB films indicated that octadecylammonium octadecanoate is formed by an intermolecular proton exchange between adjacent carboxylic and aminic groups (COO⁻ and NH₃⁺). In three-layer LB film, the CH₂ scissoring mode of the long hydrocarbon chains of octadecylammonium octadecanoate shows a broad band feature at about 1468 cm⁻¹ while this vibrational mode of three-layer LB film of the mixture (1:1) of deuterated stearic acid and octadecylamine (octadecylammonium octadecanoate-d35, C₁₈H₃₇NH₃⁺C₁₇D₃₅COO⁻) only shows a narrow band. The broad feature of the CH₂ scissoring mode in octadecylammonium octadecanoate probably originates from the coupling between the chain of stearic acid and that of octadecylamine while this kind of coupling could be completely removed in octadecylammonium octadecanoate-d35. Another conclusion presented in this paper is that there are no couplings among the chains of fatty acid or among the chains of octadecylamine in LB films of octadecylammonium octadecanoate.     

Synthesis, crystal structure, and DNA interaction and cleavage studies of a novel dinuclear Cu(II) complex with 3-indolylacetic acid

A novel dinuclear Cu(II) complex [Cu₂(C₁₀H₈NO₂)₄(CH₃OH)₂] · 2CH₃OH (I), where C₁₀H₈NO₂ is anion of 3-indolylacetic acid, was synthesized and characterized by elemental analysis, IR spectroscopy, ¹H NMR and single crystal X-ray diffraction. X-ray crystallography shows that Cu²⁺ ion is six-coordinated, embedded in a distorted octahedral center. Each Cu²⁺ ion is coordinated with four carboxylic oxygen atoms from four ligands, one oxygen atom from methanol and the other Cu²⁺ ion. Each ligand links two Cu²⁺ ions through carboxylic oxygen atoms, forming a dinuclear Cu(II) complex. The complex forms a two-dimensional layer structure through N-H??Oⁱ intermolecular hydrogen bonds. The interaction of complex I with calf-thymus DNA (CT-DNA) has been explored by electronic absorption spectroscopy, EB (ethidium bromide) displacement experiments, salt effect, and viscosity measurements. All the results indicate that the complex binds to DNA in a partial intercalative mode. Moreover, agarose gel electrophoresis assay demonstrates that the complex possesses the ability to cleave pBR322 plasmid DNA.     

A gold nanoparticle-based colorimetric sensing ensemble for the colorimetric detection of cyanide ions in aqueous solution

A colorimetric sensing ensemble was prepared by mixing readily prepared adenosine triphosphate (ATP)-stabilized AuNPs with Cu²⁺-phenanthroline complexes. The sensing mechanism of the ensemble was examined by UV-vis spectrometry and transmission electron microscopy. The studies showed that the Cu²⁺-phenanthroline complex was converted to free phenanthroline when exposed to cyanide anions and the free phenanthroline caused the ATP-stabilized AuNPs to aggregate, which in turn, resulted in a visible color change in the AuNP solution. The ensemble could detect cyanide ions in aqueous solution at physiological pH, either spectrophotometrically or visually, with high selectivity toward cyanide anions over a range of mono- and di-anions commonly found in biological and environmental systems. This sensing ensemble also allows a quantitative assay of the analyte in a neutral aqueous solution, down to a concentration of 10⁻⁵ M.     

Bis{μ‐[6‐(hydroxy­methyl)‐2‐pyridyl]­methano­lato‐κ3N,O:O}bis{[2,6‐bis­(hydroxy­methyl)­pyridine‐κ3O,N,O′]copper(II)} di­acetate

The title dinuclear Cu^II complex, [Cu₂(C₇H₈NO₂)₂(C₇H₉NO₂)₂](CH₃COO)₂, has been synthesized by the reaction of Cu(CH₃COO)₂·H₂O with pdmH₂ (pdmH₂ is pyridine‐2,6‐diyldi­methanol) in the presence of tetra­butyl­ammonium hydro­xide. The title complex contains a centrosymmetric Cu₂O₂ core and each Cu^II atom has distorted octahedral geometry. Molecular [Cu₂(pdmH)₂(pdmH₂)]²⁺ cations are connected by hydrogen bonds involving the CH₃COO⁻ anions, forming one‐dimensional chains along the a axis.     

Gold Nanoparticles Carrying Diatomic Molecules (O2 and CO) in Aqueous Solution

Gold nanoparticles (AuNPs) prepared by citrate reduction of aurochloric acid (HAuCl₄) were functionalized by tris(4‐sulfonatophenyl)porphinatoiron(III) (Fe^IIIP2) and poly(ethylene glycol) with thiolated arms (PEG‐SH). Fe^IIIP2 on the AuNP surface existed as its μ‐oxo dimer, which was reduced by Na₂S₂O₄ to yield monomeric Fe^IIP2. Fe^IIP2‐bearing AuNPs were further functionalized through inclusion of two sulfonatophenyl groups of Fe^IIP2 by a per‐O‐methylated β‐cyclodextrin dimer with a pyridine linker (Py3CD) to obtain AuNPs capable of carrying diatomic molecules in the body. The resulting AuNPs (hemoCD‐AuNPs) bound O₂ as well as CO in an aqueous solution. Although a noncolloidal 1:1 complex of 5,10,15,20‐tetrakis(4‐sulfonatophenyl)porphinatoiron(II) and Py3CD injected into the femoral vein of a rat was rapidly excreted in the urine, no excretion was observed with ferric hemoCD‐AuNPs, which were gradually accumulated in the spleen and liver of a rat. These results suggest that hemoCD‐AuNPs can be used as a carrier of diatomic molecules such as O₂ and CO in vivo.     

Analyte-triggered cyclic autocatalytic oxidation amplification combined with an upconversion nanoparticle probe for fluorometric detection of copper(II)

The authors describe an upconversion nanoparticle-based (UCNP–based) fluorometric method for ultrasensitive and selective detection of Cu²⁺. The UCNPs show a strong emission band at 550 nm under near-infrared excitation at 980 nm. The principle of the strategy is that gold nanoparticles (AuNP) can quench the fluorescence of UCNP. In contrast, the addition of L-cysteine (Cys) can induce the aggregation of AuNP, resulting in a fluorescence recovery of the UCNPs. On addition of Cu²⁺, it oxidizes Cys to cystine and is reduced to Cu⁺. The Cu⁺ thusformed can be oxidized cyclically to Cu²⁺ by dissolved O₂, which catalyzes and recycles the whole reaction. Thus, the aggregation of AuNP is inhibited and the fluorescence recovered by Cys is quenched. Under the optimal condition, the quenching efficiency shows a good linear response to the concentrations of Cu²⁺ in the 0.4–40 nM range. The limit of detection is 0.16 nM, which is 5 orders of magnitude lower than the U.S. Environmental Protection Agency limit for Cu²⁺ in drinking water (20 μM). The method has been further applied to monitor Cu²⁺ levels in real samples. The results of detection are well consistent with those obtained by atomic absorption spectroscopy.

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Graphical abstract Gold nanoparticles (AuNP) as a high efficient fluorescence quenching reagent of upconversion nanoparticles (UCNP) were used in a fluorometric method for detection of Cu²⁺ based on a cyclic catalytic oxidation amplification strategy.

     

Diaza-crown-N,N-dialkanoic acids copper(II) and dicopper(II) complexes

Twelve-, fifteen-, and eighteen-membered diaza-crown-N, N-′dialkanoic acids LH₂ and their inner salt copper(II) complexes CuL and dicopper complex [CuL(3). CuCl₂. CH₃OH_n were obtained. The complexes of 15- and 18-membered ligands contain Cu²⁺ ion inside the ring.     

Polyelectrolyte Multilayer‐Mediated Growth of Gold Nanoparticle Films with Tunable Loading Density and Nanoparticle Shape

A facile method for preparing gold nanoparticle (AuNP) films with a high loading density based on the seed‐mediated growth of AuNPs on a polyelectrolyte multilayer (PEM) is reported. Use of PEMs as a base layer for gold seed adsorption confers controllability on the loading density of the AuNP film and size of the resulting AuNPs. In addition, the shape of the final AuNPs could be varied by adapting various species of polyelectrolytes. The optical response of the AuNP films is stable, because of the relatively uniform distribution of the AuNPs over a large area. The AuNP film has been used as a substrate for surface‐enhanced Raman scattering (SERS), and it shows stable and reproducible enhancement in the range from 10⁵ to 10⁷ depending on the fabrication condition.

     

Rate Coefficients of C1 and C2 Criegee Intermediate Reactions with Formic and Acetic Acid Near the Collision Limit: Direct Kinetics Measurements and Atmospheric Implications

Rate coefficients are directly determined for the reactions of the Criegee intermediates (CI) CH₂OO and CH₃CHOO with the two simplest carboxylic acids, formic acid (HCOOH) and acetic acid (CH₃COOH), employing two complementary techniques: multiplexed photoionization mass spectrometry and cavity‐enhanced broadband ultraviolet absorption spectroscopy. The measured rate coefficients are in excess of 1×10^?10 cm³ s^?1, several orders of magnitude larger than those suggested from many previous alkene ozonolysis experiments and assumed in atmospheric modeling studies. These results suggest that the reaction with carboxylic acids is a substantially more important loss process for CIs than is presently assumed. Implementing these rate coefficients in global atmospheric models shows that reactions between CI and organic acids make a substantial contribution to removal of these acids in terrestrial equatorial areas and in other regions where high CI concentrations occur such as high northern latitudes, and implies that sources of acids in these areas are larger than previously recognized.     

Tetramethylcyclotetraarsoxane Bridging of Copper(I) Halide Units Cu6Br6, Cu2I2, [Cu6I8]2–, and [Cu3I4–] in Porous Coordination Polymers

The polymeric compounds [{Cu₂I₂(C₆H₅CN)₂[cyclo‐(CH₃AsO)₄]} · C₆H₅CN] ( 1 ) and [Cu₆Br₆(C₆H₅CN)₄{cyclo‐(CH₃AsO)₄}] ( 2 ) may be prepared by reaction of the copper(I) halide with methylcycloarsoxane (CH₃AsO)_n in benzonitrile at 100 °C. 1 contains four‐membered (CuI)₂ rings, 2 tricyclic Cu₆Br₆ units, that are connected through bridging (CH₃AsO)₄ ligands into infinite chains. π–π Stacking of terminal C₆H₅CN ligands from parallel chains leads to the construction of porous frameworks, whose cavities are large enough in the case of 1 to accommodate guest C₆H₅CN molecules. In the presence of CsI, the self‐assembly reaction of CuI with (CH₃AsO)₄ in H₂O–CH₃OH–CH₃CN (at 20 °C) or CH₃CN (at 130 °C) affords [Cs(H₂O)₂][Cu₃I₄{cyclo‐(CH₃AsO)₄}₂] · 0.5 CH₃OH ( 3 ) and Cs[Cu₃I₄{cyclo‐(CH₃AsO)₄}₂] ( 4 ), whose 1‐ and 2‐dimensional anionic coordination polymers are linked together through respectively [Cs{cyclo‐(CH₃AsO)₄‐κ⁴O}₂]⁺ and [Cs{Cu₃I₄‐κ⁴I}{cyclo‐(CH₃AsO)₄‐κ⁴O}] sandwiches.     

Simulating the active sites of copper-trafficking proteins. Density functional structural and spectroscopy studies on copper(I) complexes with thiols,carboxylato, amide and phenol ligands

A series of mononuclear binary and ternary Cu(I) complexes with formato, formamide, methylphenol, and methanethiolato ligands were optimized at DFT-B3LYP/6-31G** (BS1) and DFT-B3LYP/6-311++G** (BS2) levels of theory. The solvent effect was taken into account via PCM method (BS1W and BS2W, respectively). The coordination arrangement for [Cu^I(SCH₃/S(H)CH₃)(OOCH)]^?/0 and [Cu^I(SCH₃/S(H)CH₃)(O(H)(C₆H₄)CH₃)]^0/+ was pseudo-linear and for [Cu^I(SCH₃/S(H)CH₃)(OOCH)(OC(H)NH₂)]^?/0 was pseudo-trigonal. The [Cu^I(S-S(H)CH₃/Cu^I(S-SCH₃)]^+/0 link even to amide carbonyl and to general O(H)R residues (R=C₆H₅CH₃). [Cu^I(SCH₃)₂(O(H)(C₆H₄)CH₃)]^? went towards dissociation of the O(H)(C₆H₄)CH₃ ligand, whereas [Cu^I(S(H)CH₃)₂(O(H)(C₆H₄)CH₃)]⁺ converged nicely, maintaining the hydroxy function linked to the metal. The trends of total electronic energies seemed to be significant, suggesting that linear Cu^IS₂ coordination is more suitable than Cu^IS, Cu^IS₃ and Cu^IS₄ arrangements. The formation energies of [Cu^I(S(H)CH₃/SCH₃)(OOCH)]^0/?1 were higher than those of [Cu^I(S(H)CH₃/SCH₃)₂]^+/? on starting from [Cu^I(S(H)CH₃/Cu^I(SCH₃)]^+/0 by ca. 11–9 kcal mol^?1 (BS2W). The structural arrangements, bond distances, and angles as well as computed spectroscopic parameters resulted in good agreement with experimental data for corresponding synthetic complexes and with metal site regions of several copper(I)-proteins. These data help in interpreting structural data of complex biological systems and in constructing reliable force fields for molecular mechanics computations.     

Synthese und Strukturuntersuchungen von Iodocupraten(I). XV Iodocuprate(I) mit solvatisierten Kationen: [Li(CH3CN)4][Cu2I3] und [Mg{(CH3)2CO}6][Cu2I4]

Synthesis and Structure Investigations of Iodocuprates(I). XV Iodocuprate(I) with Solvated Cations: [Li(CH₃CN)₄] [Cu₂I₃] and [Mg{(CH₃)₂CO}₆][Cu₂I₄] [Li(CH₃CN)₄][Cu₂I₃] 1 and [Mg((CH₃)₂CO)₆][Cu₂I₄] 2 were prepared by reactions of CuI with LiI in acetonitrile and of CuI with MgI₂ in acetone. 1 crystallizes orthorhombic, Pnma, a = 552.7(2), b = 1258.8(8), c = 2516(1) pm, z = 4. [Li(CH₃CN)₄]⁺ cations are located between rod packings of CuI₄ tetrahedra double chains [(CuI_2/2I_2/4)₂]^? parallel to the axis. Short intermolecular anion/cation contacts were observed. The crystal structure of 2 (monoclinic, P2₁/n, a = 1840(2), b = 1059.2(2), c = 1879(2)pm, β = 112.94(4)°, z = 4) is built up by [Mg((CH₃)₂CO)₆]²⁺ cations forming a simple hexagonal sphere packing. The binuclear anions [Cu₂I₄]^2? occupy holes in the trigonal prismatic channels formed by the cations.     

An ultrasensitive hydrogen peroxide biosensor based on electrocatalytic synergy of graphene–gold nanocomposite, CdTe–CdS core–shell quantum dots and gold nanoparticles

We first reported an ultrasensitive hydrogen peroxide biosensor in this work. The biosensor was fabricated by coating graphene–gold nanocomposite (G–AuNP), CdTe–CdS core–shell quantum dots (CdTe–CdS), gold nanoparticles (AuNPs) and horseradish peroxidase (HRP) in sequence on the surface of gold electrode (GE). Cyclic voltammetry and differential pulse voltammetry were used to investigate electrochemical performances of the biosensor. Since promising electrocatalytic synergy of G–AuNP, CdTe–CdS and AuNPs towards hydrogen peroxide was achieved, the biosensor displayed a high sensitivity, low detection limit (S/N = 3) (3.2 × 10⁻¹¹ M), wide calibration range (from 1 × 10⁻¹⁰ M to 1.2 × 10⁻⁸ M) and good long-term stability (20 weeks). Moreover, the effects of omitting G–AuNP, CdTe–CdS and AuNP were also examined. It was found that sensitivity of the biosensor is more 11-fold better if G–AuNP, CdTe–CdS and AuNPs are used. This could be ascribed to improvement of the conductivity between graphene nanosheets in the G–AuNP due to introduction of the AuNPs, ultrafast charge transfer from CdTe–CdS to the graphene sheets and AuNP due to unique electrochemical properties of the CdTe–CdS, and good biocompatibility of the AuNPs for horseradish peroxidase. The biosensor is of best sensitivity in all hydrogen peroxide biosensors based on graphene and its composites up to now.     

Cations Controlling the Chiral Assembly of Luminescent Atomically Precise Copper(I) Clusters

Chiral assembly and asymmetric synthesis are critically important for the generation of chiral metal clusters with chiroptical activities. Here, a racemic mixture of [K(CH₃OH)₂(18‐crown‐6)]⁺[Cu₅(S^tBu)₆]^? ( 1?CH₃OH ) in the chiral space group was prepared, in which the chiral red‐emissive anionic [Cu₅(S^tBu)₆]^? cluster was arranged along a twofold screw axis. Interestingly, the release of the coordinated CH₃OH of the cationic units turned the chiral 1?CH₃OH crystal into a mesomeric crystal [K(18‐crown‐6)]⁺[Cu₅(S^tBu)₆]^? ( 1 ), which has a centrosymmetric space group, by adding symmetry elements of glide and mirror planes through both disordered [Cu₅(S^tBu)₆]^? units. The switchable chiral/achiral rearrangement of [Cu₅(S^tBu)₆]^? clusters along with the capture/release of CH₃OH were concomitant with an intense increase/decrease in luminescence. We also used cationic chiral amino alcohols to induce the chiral assembly of a pair of enantiomers, [d /l ‐valinol(18‐crown‐6)]⁺[Cu₅(S^tBu)₆]^? ( d /l ‐Cu_5V ), which display impressive circularly polarized luminescence (CPL) in contrast to the CPL‐silent racemic mixture of 1?CH₃OH and mesomeric 1 .     

Self-assembly of ultra-small gold nanoparticles on an indium tin oxide electrode for the enzyme-free detection of hydrogen peroxide

A novel enzyme-free electrochemical sensor for H₂O₂ was fabricated by modifying an indium tin oxide (ITO) support with (3-aminopropyl) trimethoxysilane to yield an interface for the assembly of colloidal gold. Gold nanoparticles (AuNPs) were then immobilized on the substrate via self-assembly. Atomic force microscopy showed the presence of a monolayer of well-dispersed AuNPs with an average size of ~4 nm. The electrochemical behavior of the resultant AuNP/ITO-modified electrode and its response to hydrogen peroxide were studied by cyclic voltammetry. This non-enzymatic and mediator-free electrode exhibits a linear response in the range from 3.0?×?10^?5 M to 1.0?×?10^?3 M (M?=?mol?·?L^?1) with a correlation coefficient of 0.999. The limit of detection is as low as 10 nM (for S/N?=?3). The sensor is stable, gives well reproducible results, and is deemed to represent a promising tool for electrochemical sensing.

A comparative theoretical study of the reactivities of the Al+ and Cu+ ions toward methylamine and dimethylamine

A very recent laser ablation‐molecular beam experiment shows that an Al⁺ ion can react with a single methylamine (MA, CH₃NH₂) or dimethylamine (DMA, (CH₃)₂NH) molecule to form a 1:1 ion–molecule complex Al⁺[CH₃NH₂] or Al⁺[(CH₃)₂NH)], whereas a dehydrogenated complex ion Cu⁺[CH₃N] or Cu⁺[C₂H₅N] is detected, respectively, in the similar reaction for a Cu⁺ ion. Here, we show a comparative density functional theory study for the reactivities of the Al⁺ and Cu⁺ ions toward MA and DMA to reveal the intrinsic mechanism. It is found that the interactions of the Al⁺ ion with MA and DMA are mostly electrostatic, leading to the direct ion–molecule complexes, Al⁺? NH₂CH₃ and Al⁺? NH( CH₃)₂, in contrast to the non‐negligible covalent character in the corresponding Cu⁺‐containing complexes, Cu⁺? NH₂CH₃ and Cu⁺? NH( CH₃)₂. The general dehydrogenation mechanism for MA and DMA promoted by the Cu⁺ ion has been shown, and the preponderant structures contributing to the mass spectra of the product ions Cu⁺[CH₃N] and Cu⁺[C₂H₅N] are rationalized as Cu⁺? NHCH₂ and Cu⁺? N( CH₂)( CH₃). The presumed dehydrogenation reactions are also discussed for the Al⁺‐containing systems. However, the involved barriers are found to be too high to be overcome at low energy conditions. These results have rationalized all the experimental observations well. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

GC-MS quantitation of benzoic and aralkyl carboxylic acids as their trimethylsilyl derivatives: In model solution I

Summary This paper describes the fragmentation patterns and the GC-MS quantitation possibilities of the trimethylsilyl derivatives of thirty-one aromatic carboxylic acids, using ion trap detection (ITD). Sixteen aralkyl carboxylic acids, including those containing a saturated aliphatic side chain {phenylacetic, 2-phenylbutyric, phenylglycolic (mandelic acid), β-phenyllactic, 3-hydroxyphenylacetic, β-phenylpyruvic and 3-(4-hydroxyphenyl)-propionic acids} and those with an unsaturated aliphatic side chain {cinnamic, 2-hydroxycinnamic (o-coumaric), 4-methoxycinnamic, 3-hydroxycinnamic (m-coumaric), 4-hydroxycinnamic (p-coumaric), 4-hydroxy-3-methoxycinnamic (ferulic acid), 3,4-dihydroxycinnamic (caffeic), and 4-dihydroxy-3,5-dimethoxycinnamic (sinapic) acids}, as well as, the fifteen hydroxy(methoxy) benzoic acids {benzoic, 2-hydroxybenzoic (salicylic), 3-hydroxybenzoic, 4-hydroxybenzoic, 3,5-dimethoxybenzoic, 3,4-dimethoxybenzoic (veratric), 2,6-dihydroxybenzoic (γ-resorcylic), 3-methoxy-4-hydroxybenzoic (vanillic), 2,5-dihydroxybenzoic (gentisic), 2,4-dihydroxybenzoic (β-resorcylic), 3,4-dihydroxybenzoic (protocatechuic), 3,5-dihydroxybenzoic (α-resorcylic), 2,4,5-trimethoxybenzoic (asaronic), 3,5-dimethoxy-4-hydroxybenzoic (syringic) and 3,4,5-trihydroxybenzoic (gallic) acids}, provided distinct fragmentation characteristics that were very useful for their identification and simultaneously quantitation. Based on 1–20 ng amounts of acids, very informative ions of high mass with considerable intensities ([M+TMS]⁺, [M+1]⁺), , ([M−CH₃]⁺) were obtained. In the case of the cinnamic acid derivatives, several odd electron fragments are formed by the loss of CO, HCHO and/or Si(CH₃)₄ molecules. In the case of benzoic acids the molecular ion proved to be abundant in three, the [M−CH₃]⁺ ion in nine cases out of fifteen. The special MacLafferty rearrangement product ([C₆H₅Si(CH₃)₂]⁺) was obtained in different yields. In addition to the TIC values, at least three, and in most cases four, selective fragment ions could be utilized for quantitation. The reproducibility of the data in the concentration range of 1–20 ng acids proved to be between 1.2 and 13.0% (R.S.D.). Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997