Girard's Reagent Research Articles

Determination of sub-ppbv levels of formaldehyde in ambient air using Girard's reagent T-coated glass fiber filters and adsorption voltammetry

Formaldehyde (HCHO) present in ambient air was trapped on a standard minature glass fiber filter impregnated with Girard's reagent T (GRT). The formaldehyde hydrazone formed (i.e. the adduct of formaldehyde and Girard's reagent T, FGA) is desorbed from the filter with water and determined by adsorption voltammetry. Recovery of formaldehyde as the FGA from a 13 mm impregnated filter is 87–104% in the range 0.06–30 μg of formaldehyde. This corresponds to 2.0–1000 μg m −3 in a 30 1 air sample. The collection efficiency of the coated filter is greater than 90%. The GRT-coated glass fiber filter can be sampled at a rate of up to 1 l min −1 when the system is used in the active mode, and a detection limit of about 1 μg m −3 (corresponding to about 0.7 ppbv HCHO at standard state) based on a 30 1 air sample is obtained. Results are given from measurements of formaldehyde in ambient air of both indoor and outdoor environments.

Modification of Arginine-198 in Sarcoplasmic Reticulum Ca2+-ATPase by 1,2-Cyclohexanedione Causes Inhibition of Formation of the Phosphoenzyme Intermediate from Inorganic Phosphate

Sarcoplasmic reticulum vesicles were modified with 1,2-cyclohexanedione (CHD), a specific arginine-modifying reagent, in sodium borate (pH 8.0 or 8.8). Phosphoenzyme formation from Pi in the Ca2+-ATPase (reversal of hydrolysis of the phosphoenzyme intermediate) was almost completely inhibited by the modification with CHD. Tight binding of F- and Mg2+ and high affinity binding of vanadate in the presence of Mg2+, either of which produces a transition state analog for phosphoenzyme formation from the magnesium-enzyme-phosphate complex, were also markedly inhibited. In contrast, phosphoenzyme formation from acetyl phosphate in the forward reaction was unaffected. The enzyme was appreciably protected by tight binding of F- and Mg2+ or by high affinity binding of vanadate in the presence of Mg2+, but not by the presence of 20 mM MgCl2 alone or 150 mM Pi alone, against the CHD-induced inhibition of phosphoenzyme formation from Pi. Peptide mapping of the tryptic digests, detection of peptides containing CHD-modified arginyl residues with Girard's reagent T, sequencing, and mass spectrometry showed that Arg-198 was a single major residue protected by tight binding of F- and Mg2+ against the modification with CHD. These results indicate that modification of Arg-198 with CHD is responsible for at least a part (the portion reduced by the transition state analogs) of the CHD-induced inhibition of phosphoenzyme formation from Pi and suggest that Arg-198 is located in or close to the catalytic site in the transition state for phosphoenzyme formation from the magnesium-enzyme-phosphate complex.

Adsorption voltammetric determination of μg 1 −1 levels formaldehyde via in situ derivatization with Girard's reagent T

The adsorptive voltammetric behaviour of formaldehyde (HCHO) after its in situ derivatization with trimethylaminoacetohydrazide chloride (Girard's reagent T) at a hanging mercury drop electrode (HMDE) was investigated in NH 3-NH 4Cl (pH 9.7) solution. The results showed that the adduct of HCHO with Girard's reagent T can be adsorbed on the surface of the HMDE, yielding one peak at −1280 mV (vs Ag AgCl electrode), corresponding to the reduction of the adduct. The limit of detection was as low as 8.0 × 10 −8 mol dm −3 (corresponding to 2.4 μg dm −3 of HCHO). The linear range of the method was 2.0 × 10 −7~8.0 × 10 −6 mol dm −3. The sensitivity of the method allows its application for the direct determination of HCHO in rain water samples.

Isolation and purification method of 6-oxoestradiol using Girard's reagent P.

An efficient synthetic method of 6-oxoestradiol was established by modifying the previous method by Garza and Rao. The present method is characterized by the quantitative extraction of 6-oxoestradiol produced during an oxidation reaction using Girard's reagent P (GP). The procedure is as follows: (1) reaction of estradiol-3, 17-diacetate with 5-dimethylpyrazole/chromium trioxide complex in dichloromethane; (2) column chromatography (SiO2) of the reaction mixture to obtain steroidal fraction by dichloromethane as an eluent, followed by saponification of the eluate; (3) reaction of the product with GP in methanol; (4) removal of the nonketonic steroid from an aq. layer, where the hydrazone of 6-oxoestradiol is remained; (5) formation of 6-oxoestradiol by acidification of the aq. layer. The overall yield of the 6-oxoestradiol from estradiol was greater than 45 percent.

Identification of Arginyl Residues Located at the ATP Binding Site of Sarcoplasmic Reticulum Ca2+-ATPase: MODIFICATION WITH 1,2-CYCLOHEXANEDIONE

Sarcoplasmic reticulum vesicles were treated with 1, 2-cyclohexanedione (CHD) in sodium borate (pH 8.0). The Ca2+-ATPase activity was completely inhibited. Inhibition of Mg.ATP and Mg.ADP binding to the high affinity ATP binding site as well as inhibition of phosphorylation with ATP occurred simultaneously with the inhibition of the Ca2+-ATPase activity. Phosphorylation with acetyl phosphate was not inhibited. The Ca2+-ATPase was strongly protected by Mg.ATP, Mg.ADP, and Mg.AMP against this inhibition. Binding of acetyl phosphate or Pi to the enzyme gave no protection. Phosphorylation with acetyl phosphate also had no protective effect. Peptide mapping of the tryptic digests, detection of peptides containing CHD-modified arginyl residues with Girard's reagent T, and sequencing revealed that Arg-489, Arg-505, and Arg-678 were modified with CHD. Arg-489 and Arg-678 were almost completely protected by Mg.ATP against this modification, but partially protected by prelabeling with fluorescein 5-isothiocyanate, which occupies the adenosine binding region in the ATP binding site. In contrast, Arg-505 was slightly protected by Mg.ATP and almost completely protected by prelabeling with fluorescein 5-isothiocyanate. Taken together, these findings suggest that Arg-489 and Arg-678 are located in or near the region occupied by the triphosphate moiety of ATP, either or both of these residues being in or close to the region occupied by the alpha-phosphoryl group in the high affinity ATP binding site and involved in the CHD-induced inhibition of this enzyme and that Arg-505 is very close to (but slightly out of) the adenosine binding region in the ATP binding site. The acetyl phosphatase activity and phosphorylation with Pi were also inhibited by the CHD treatment, but the inhibitions were considerably slower than those described above. This suggests that the arginyl residues involved in these inhibitions are distinct from that involved in the inhibition of the Ca2+-ATPase activity.

Application of Nafion-coated mercury film electrodes to the microdetermination of formaldehyde by differential-pulse voltammetry

Formaldehyde, after in situ conversion to an ionic derivative with Girard's reagent T, was first accumulated on a Nafion-coated mercury film electrode. The adsorbed derivative was then determined in aqueous solution using differential-pulse voltammetry. A single peak centred at –1.24 V (versus Ag–AgCl) was observed at pH 9.7 when using 0.4 mol l–1 NH4Cl–NH3 as the supporting electrolyte. The calibration graphs were rectilinear over the range from 2.0 × 10–7 to 1.0 × 10–5 mol l–1 formaldehyde. By incorporating a preconcentration step via the Nafion-modified electrode, the detection limit of the method for formaldehyde was calculated to be 3.4 × 10–8 mol l–1. The reproducibility and lifetime studies of the electrodes indicated that a newly prepared electrode could be repeatedly used for more than ten measurements with satisfactory precision. In addition, the method can be extended, without any modification, to the determination of acetaldehyde.

An Improved Method for Separating Paclitaxel and Cephalomannine Using Ozone and Girard Reagents.

An Improved Method for Separating Paclitaxel and Cephalomannine Using Ozone and Girard Reagents.

Differential-pulse polarographic micro-determination of formaldehyde via in situ derivatization with Girard's reagent T

Formaldehyde, after in situ derivatization with Girard's reagent T, was determined in aqueous solution using differential-pulse polarography. A single peak was obtained at pH 8 when using 1 × 10–3 mol l–1 NH4Cl/NH3 as the supporting electrolyte. The minimum detectable concentration of formaldehyde was 1.3 × 10–6 mol l–1. As little as 0.2 µg of formaldehyde can be determined accurately by using this method. In addition, acetaldehyde was proven to not interfere with the formaldehyde determination.

Ion-selective electrodes based on calix[4]arene tetraester in the determination of formaldehyde via in situ generation of ionic lipophilic hydrazone

A formaldehyde-selective electrode was designed based on the host–guest interaction between p-tert-butylcalix[4]arene tetraester and lipophilic hydrazone generated in situ from formaldehyde and a modified Girard's reagent G2. The poly(vinyl chloride) membrane electrode contains 4.5% m/m of a tetraester derivative of calix[4]arene as the neutral carrier and dioctyl phthalate as the plasticizer. At pH 5.4, the electrode exhibits a dicationic Nernstian response in the range 4 × 10–5–0.1 mol l–1 formaldehyde with a slope of 32.4 mV per decade. In contrast, at pH 9.2, the electrode shows a near Nernstian response with a slope of 50.3 mV per decade in a narrower working concentration range. The electrode has a fast response time and a long working lifetime. The viability of using the electrode for the micro-determination of formaldehyde was also demonstrated.

Synthesis, characterization and crystal structures of two cis-dioxo vanadium(V) complexes of monoanionic tridentate schiff base ligands

Reaction of Sal-L (Sal=salicylaldehyde; L=Girard reagent P or T) with (C 2H 4) 4NVO 3 yielded the title complexes, which have been characterized by elemental analysis, 1H NMR, IR spectra and conductance measurement. The X-ray crystal analyses of the compounds reveal that the molecules possess a VO 2 + unit which is in cis-configuration. From the structures, we can also see that the ligands are present as tridentate donors coordinating through the atoms of ONO, which form a distorted trigonal bipyramid configuration in complex II and a square pyramid in complex I.

Aldehyde-selective polymeric membrane electrodes based on a calix[4]arene ionophore

A novel type of aldehyde-selective electrode was designed based on the host–guest interaction between p-tert-butylcalix[4]arene ionophore and hydrazone generated in situ from heptanal and Girard's reagent P. The poly(vinyl chloride) membrane electrode contains 3.5–8% m/m of a tetraester derivative of calix[4]arene as the neutral carrier and dioctyl phthalate as the plasticizer. At pH 5.5, the electrode exhibits a Nernstian response in the range 1 × 10–2–9 × 10–7 mol l–1 heptanal with a slope of 67.7 mV per concentration decade. The electrode has a fast response time and a constant Nernstian response after 2 months of continuous measurement. The viability of using the electrode for the micro-determination of heptanal was also demonstrated. The minimum detectable concentration of aldehyde is 3 × 10–5 mol l–1, or, as little as 3.4 µg of heptanal can be determined accurately by the method.

Ion-selective electrodes in organic analysis: determination of vanillin via in situ generation of its Girard's reagent P derivative

A hydrazone-selective electrode based on the vanillin hydrazone-tetraphenylborate ion pair in a poly(vinyl chloride) matrix membrane is proposed for the determination of vanillin. Vanillin was first reacted with Girard's reagent P [1-(carbazoylmethyl)pyridinium chloride] to give the corresponding hydrazone in aqueous solution. The hydrazone was generated in situ and was then determined with the vanillin hydrazone-selective electrode. The electrode exhibits significant potentiometric response in the concentration range 10–2–4 × 10–5M hydrazone. It has a working pH range of 4.5–6, a short static response time (less than 60 s) and the response remains stable for at least 1 month. The results obtained with the proposed method agreed well with those given by UV spectrophotometry. This methodology could be extended to carbonyl compounds.

Direct introduction of a formamido group into the 7.ALPHA.(6.ALPHA.)-position of cephalosporins (pencillins).

A novel direct introduction of a formamido group into the 7 alpha (6 alpha)-position of cephalosporins (penicillins) was achieved by treatment of 7 beta (6 beta)-[(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadien-1- ylidene)methylimino]cephem (penam) esters with N,N-bis(trimethylsilyl)formamide, followed by deblocking with Girard reagent T to give the corresponding 7 alpha (6 alpha)-formamido-7 beta (6 beta)-amino derivatives. Three 7 alpha-formamidocephalosporins were prepared by the conventional N-acylation of 7 alpha-formamidocephem. All of them were resistant to beta-lactamases, showing similar MIC values against both of a pair of a beta-lactamase-producing strain and the corresponding non or low-producing strain of the same species of bacteria, when tested on Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, Proteus mirabilis, Proteus vulgaris, Morganella morganii, Enterobacter cloacae and Citrobacter freundii.

Enrichment of Aldehydes and Ketones in Sherry

ABSTRACTAn enrichment technique for aldehydes and ketones using Girard's reagent T was used on Oloroso sherry. The gas chromatogram for the enriched extract was relatively simple and showed peaks that were obscured in the chromatogram of the unenriched extract. As a result, 2‐acetofuran, 5 methylfurfural, acetophenone, 2‐thiophenecarboxal‐dehyde, α‐methylcinnamaldehyde, and cinnamaldehyde were identified in sherry for the first time. The enrichment process was carried out at temperatures lower than 35°C.

Study of profile analysis on urinary free steroids using high performance liquid chromatography with spectrophotometric scanning by photodiode array--application of Girard reagent T for sample preparation

High performance liquid chromatography (HPLC) has been useful for profile analysis of steroids. However, the conventional extraction of urinary free steroids using urine specimens has some disadvantages because of lots of interfering substances simultaneously extracted from the urine. These substances were usually detected on the chromatogram at the range of relatively short retention time within which some urinary free steroids were heavily contaminated. Therefore it seemed unsuitable for profile analysis of urinary free steroids by HPLC. In this study, we developed a relatively simple and reproducible method for removing the interfering substances by Girard reagent T. In addition, the purity of each extracted free steroids were confirmed by Photodiode Array continuous scanning system, together with 3-dimensional chromatogram as well as contour map analyzed by the attached computer. The extraction procedure was as follows: (1) 10% volume of 24-h specimens of urine included 1 microgram internal standard was charged to Sep-pack C18 cartridge. The cartridge was eluted with 20 micromilligram ethyl acetate and the eluate was evaporated. (2) 10 mg Girard reagent T dissolved in 0.5 micromilligram acetic acid and 0.5 micromilligram ethanol was added to the residue, then left at room temperature for 2 hours. During this time, ketosteroids formed by the action of Girard reagent T turned to be water-soluble hydrazone complex. (3) After the addition of 10 micromilligram cold water, it was adjusted to pH 8 with NaOH and NaHCO3, then washed with 5 volumes of ethyl acetate (non-ketotic fraction). (4) The lower layer were hydrolyzed by adding 0.5 micromilligram concentrated hydrogen chloride and left for an hour at room temperature, then the liberated steroids were extracted with ethyl acetate (ketotic fraction). (5) Ethyl acetate extract was evaporated and redissolved in the mobile phase, then injected to HPLC. To determine the effect of Girard's separation non-ketotic fraction was also applied to HPLC. The results were as follows: (1) 3-dimensional chromatogram and contour map confirmed the effectiveness of our Girard's separation. The chromatogram of ketotic fraction showed the clear separation of the peaks of 4-ene-3-one steroids in ultraviolet absorbance at 246 nm and each steroid peaks were identical to those of the reference steroids. (2) Urinary non-specific substances moving into non-ketotic fraction was complete and satisfactory.(ABSTRACT TRUNCATED AT 400 WORDS)

Derivatization of ketosteroids for fast atom bombardment mass spectrometry.

Girard's reagents were used to derivatize ketosteroids and conjugates for analysis by positive ion fast atom bombardment mass spectrometry. Spectra contain an abundant ion corresponding to the cation (C+) of the newly formed ionic derivative (C+A-) and relatively little fragmentation. With derivatization, detection of ketosteroids at a concentration of 1 microgram microliter-1 in glycerol was straightforward. Such derivatization schemes may prove useful in the analysis of ketosteroids in complex biological mixtures.

Specific micro-radioimmunoassay for prednisolone in serum.

Use of an 125I radioimmunoassay involving antiserum coupled to magnetizable cellulose, after prednisolone-21-phosphate interference is removed by dichloromethane extraction at pH 7.4 and endogenous glucocorticoid interference is removed by selective chemical derivatization with Girard's Reagent T [(carboxymethyl)trimethylammonium chloride hydrazide], allows determination of prednisolone in 10 microL of serum. Results correlate well with those of an established liquid-chromatographic method for separating prednisolone from its metabolites.

Solid-phase reagents for the isolation and protection of carbonyl compounds

Resins which can serve as solid-phase Girard reagents have been prepared. These consist of porous cross-linked polystyrene-divinylbenzene matrices functionalized either with acid hydrazide groups, 1 or with O-alkylhydroxylamine groups, 2. Both resins react rapidly, under acid catalysis, with steroidal ketones and with glucose to form resin bound carbonyl derivatives. The carbonyl compound can be recovered by exchange with acetone under mildly acidic conditions. Resin 2 was used to extract steroidal ketones from an extract of bovine adrenals. By protecting the C-20 ketone group of allopregnanolone, resin 2 was used to prepare the counterpart of the steroid bearing tritium in the 3α-position.

Organic reactions in a solid matrix-vi : Silica-gel supported reagents for the isolation of aldehydes and ketones

Semicarbazide-on silica gel and Girard-T-on-silica gel are described and evaluated as convenient reagents for efficient isolation of aldehydes and ketones from mixtures with other usual neutral organic components Semicarbazide-on-silica gel, which can be readily prepared, can effectively replace the classical Girard reagents, for the isolation of aldehydes and ketones in most cases.

Improvement of cobalt-transport in axons by complexing agents

The use of the cobalt technique is limited by the fact that cobaltous ions travel within axons for a shorter distance than do other intracellular markers. In the present experiments different organic cobaltous complexes were tested in the rat's sciatic nerve. Cobaltous complexes containing ornithine, threonine, lysine or Girard's reagent travelled two or three times further than did the cobaltous ions alone. Using the lysine complex in the frog's visual system, very fine terminals were observed which have never been demonstrated with other techniques. The possible use of other metal complexes as intracellular markers are also discussed.