A sample holder leading to improved mass spectra
1
NEW TECHNIQUES 3. (a) H.4. Schulten and H. M. Schiebel, Naturwissenschaften 65, 223 (1978); (b) H. Morris, A. Riddoch, J. R. Chap- man, M. L. Aspinal, K. R. Compson and R. A. McDowell, Adv. Mass Spec- trorn. 78, 832 (1978); (c) R.-P. Hinze, H. M. Schiebel, H. Lass, K.-P. Heise, A. Gossauer and H. H. Inhoffen, Liebigs Ann. Chem. 811 (1979); (d) H. M. Schiebel and H.-R. Schulten, Tet- rahedron 35, 1191 (1979); (e) H. M. Schiebel and H.-R. Schulten, Natur- wissenschaften 67, 256 (1980); (f) H. M. Schiebel and H.-R. Schulten, Biomed. Mass Spectrom. in press. 4. M. Barber, R. S. Bordoli, R. D. Sedg- wick and A. N. Tyler, Biorned. Mass Spectrom. 8, 492 (1981). 5. (a) M. Barber, R. S. Bordoli, R. D. Sedgwick and A. N. Tyler, Nature (London) 293, 270 1981; (b) D. J. Sur- man and J. V. Vickerman, J. Chem. SOC. Chem. Commun. 324 (1981); (c) M. Barber, R. S. Bordoli, R. D. Sedg- wick and A. N. Tyler, J. Chem. SOC. Chem. Commun. 325 (1981); (d) D. H. Williams, C. Bradley, G. Bojesen, S. Santikarn and L. C. E. Taylor, J. Am. Chem. SOC. 103, 5600 (1981). 6. Similar observations were made by Schiebel and Schulten. We thank Dr H. M. Schiebel, Braunschweig, for communicating their results prior to publication. 7. L. Ernst, G. Holze and H. H. Inhoffen, Liebigs Ann. Chem. 198 (1981). New Techniques A Sample Holder Leading to Improved Mass Spectra In recent papers'-' we have presented a part of our results concerning the use of a gold sample holder to obtain electron im- pact mass spectra of non-volatile substances. The originality of the use of gold for an extended probe is confirmed by the excel- lent review of Cotter4 published practically simultaneously with our note.' In our laboratory, gold has repeatedly been con- firmed in its unique advantages over Vespel, quartz, platinum, etc. in non-heated ex- tended probes; this may be due to its ex- treme inertness, lack of catalytic properties and/or thermal conductivity (cf. the efFi- ciency of a fast-heated extended probe made of other material^).".^ The use of a gold extended probe is a very simple proce- dure, and in this note we describe the con- struction of the gold probe used. We adapted the gold sample holder on the insertion rod existing in the laboratory. Two types of mass spectrometer were used: a Finnigan 4021 mass spectrometer and a Thomson TH-208 B double focusing instru- ment. In the case of the Thomson TH-208 B mass spectrometer the source block is a standard electron impact source with the heaters inserted in the block. The ionization chamber is a rectangular shaped cavity into which the probe is introduced. The gold sample holder is fixed on the end of the direct insertion rod which is introduced via the vacuum lock in the ion source. In the first experiments the sample holder was fixed to a Vespel support (S). The use of a metallic support did not change the relative intensities in the mass spectra. The sample material was either deposited onto the gold sample holder (Fig. 1) in a syringe. The sample holder may be ex- changed: the shape (C) is used for solid sampleslspiral or 'snail' shape and 'loop' (B) for solutions. In the first experiments the sample had been deposited on the top of a gold rod (A) 4 mm in length and 1 mm in diameter. The rod was perpendicular to the electron beam. The distance between the end of the rod and the electron beam was 7mm. To decrease the time between the desorption and the ionization a shorter dis- tance has now been adopted: 2-3 mm. The distance is not critical, however. The probe is introduced into the ion source which is maintained at a temperature dependent upon the nature of the sample. The yield of molecular or quasimolecular ions can be optimized by adjusting the temperature of the ion source and by adapt- ing the shape of the sample holder (Fig. 1, shapes B, C). We have tested thin (d= 0.5 mm) and thicker (d = 1 mm) gold wires. A longer thin wire gives better results than a thicker wire having the same mass. The (B) type sample holder was adapted to the existing insertion rod of the Finnigan 4021 mass spectrometer. The main results can be summarized as follows. For substances requiring field de- sorption or other special techniques, the very simple technique described here often gives molecular or quasimolecular ions, with relatively high absolute yields and with characteristic fragment^.'-^ No change is re- quired in the procedure used to obtain the mass spectra. The authors thank Professor G. Ourisson for critical reading of the original manus- cript. EMILIA CONSTANTIN Institut de Chimie, SpectromCtrie de Masse Moderne, LA 31, 1 rue Blaise Pascal, 67000 Strashourg, France RAYMOND HUEBER Institut de Chimie, Service de SpectromBtrie de Masse 1 rue Blaise Pascal, 67000 Strasbourg, France Figure 1. Different shapes of the sample holder: (A) rod type; (B) shape used for the solutions: IC) 'snail' tvDe used for References 1. E. Constantin, Y. Nakatani, G. Ouris- son, R. Hueber and G. Teller, Tet- rahedron Lett. 4745 (1980). 2. E. Constantin, Y. Nakatani, G. Teller, R. Hueber and G. Ourisson, Bull. SOC. Chim. Fr. /I 303 (1981). 3. E. Constantin, B. Dietrich, M. W. Hos- seini, J. M. Lehn and R. B. Session, Proceedings of the 8th Mass Spec- trometry Conference, 18-19 June 1981, Elsevier, Amsterdam, in press. 4. R. 2. Cotter, Anal. Chem. 52, 1589A (1980). 5. D. Dessort and A. Van Dorsselaer, Tet- rahedron Lett. 1395 (1982). solid state or the sample was dissolved in a suitable solvent and deposited with a solutions). V = Vespel; S= support. Received 11 January 1982 solid samples (may also 'be used for 460 ORGANIC MASS SPECTROMETRY, VOL. 17, NO. 9, 1982 @ Wiley Heyden Ltd, 1982
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Transcript of A sample holder leading to improved mass spectra
NEW TECHNIQUES
3. (a) H . 4 . Schulten and H. M. Schiebel, Naturwissenschaften 65, 223 (1978); (b) H. Morris, A. Riddoch, J. R. Chap- man, M. L. Aspinal, K. R. Compson and R. A. McDowell, Adv. Mass Spec- trorn. 78, 832 (1978); (c) R.-P. Hinze, H. M. Schiebel, H. Lass, K.-P. Heise, A. Gossauer and H. H. Inhoffen, Liebigs Ann. Chem. 811 (1979); (d) H. M. Schiebel and H.-R. Schulten, Tet- rahedron 35, 1191 (1979); (e) H. M. Schiebel and H.-R. Schulten, Natur-
wissenschaften 67, 256 (1980); (f) H. M. Schiebel and H.-R. Schulten, Biomed. Mass Spectrom. in press.
4. M. Barber, R. S. Bordoli, R. D. Sedg- wick and A. N. Tyler, Biorned. Mass Spectrom. 8, 492 (1981).
5. (a) M. Barber, R. S. Bordoli, R. D. Sedgwick and A. N. Tyler, Nature (London) 293, 270 1981; (b) D. J. Sur- man and J. V. Vickerman, J. Chem. SOC. Chem. Commun. 324 (1981); (c) M. Barber, R. S. Bordoli, R. D. Sedg-
wick and A. N. Tyler, J. Chem. SOC. Chem. Commun. 325 (1981); (d) D. H. Williams, C. Bradley, G. Bojesen, S. Santikarn and L. C. E. Taylor, J. Am. Chem. SOC. 103, 5600 (1981).
6. Similar observations were made by Schiebel and Schulten. We thank Dr H. M. Schiebel, Braunschweig, for communicating their results prior to publication.
7. L. Ernst, G. Holze and H. H. Inhoffen, Liebigs Ann. Chem. 198 (1981).
New Techniques
A Sample Holder Leading to Improved Mass Spectra
In recent papers'-' we have presented a part of our results concerning the use of a gold sample holder to obtain electron im- pact mass spectra of non-volatile substances. The originality of the use of gold for an extended probe is confirmed by the excel- lent review of Cotter4 published practically simultaneously with our note.' In our laboratory, gold has repeatedly been con- firmed in its unique advantages over Vespel, quartz, platinum, etc. in non-heated ex- tended probes; this may be due to its ex- treme inertness, lack of catalytic properties and/or thermal conductivity (cf. the efFi- ciency of a fast-heated extended probe made of other material^).".^ The use of a gold extended probe is a very simple proce- dure, and in this note we describe the con- struction of the gold probe used.
We adapted the gold sample holder on the insertion rod existing in the laboratory. Two types of mass spectrometer were used: a Finnigan 4021 mass spectrometer and a Thomson TH-208 B double focusing instru- ment.
In the case of the Thomson TH-208 B mass spectrometer the source block is a standard electron impact source with the heaters inserted in the block. The ionization chamber is a rectangular shaped cavity into which the probe is introduced. The gold sample holder is fixed on the end of the direct insertion rod which is introduced via the vacuum lock in the ion source. In the first experiments the sample holder was fixed to a Vespel support (S). The use of a metallic support did not change the relative intensities in the mass spectra.
The sample material was either deposited onto the gold sample holder (Fig. 1) in a
syringe. The sample holder may be ex- changed: the shape (C) is used for solid sampleslspiral or 'snail' shape and 'loop' (B) for solutions. In the first experiments the sample had been deposited on the top of a gold rod (A) 4 mm in length and 1 mm in diameter. The rod was perpendicular to the electron beam. The distance between the end of the rod and the electron beam was 7mm. To decrease the time between the desorption and the ionization a shorter dis- tance has now been adopted: 2-3 mm. The distance is not critical, however.
The probe is introduced into the ion source which is maintained at a temperature dependent upon the nature of the sample.
The yield of molecular or quasimolecular ions can be optimized by adjusting the temperature of the ion source and by adapt- ing the shape of the sample holder (Fig. 1, shapes B, C). We have tested thin ( d = 0.5 mm) and thicker (d = 1 mm) gold wires. A longer thin wire gives better results than a thicker wire having the same mass.
The (B) type sample holder was adapted to the existing insertion rod of the Finnigan 4021 mass spectrometer.
The main results can be summarized as follows. For substances requiring field de- sorption or other special techniques, the very simple technique described here often gives molecular or quasimolecular ions, with relatively high absolute yields and with characteristic fragment^.'-^ No change is re- quired in the procedure used to obtain the mass spectra.
The authors thank Professor G. Ourisson for critical reading of the original manus- cript.
EMILIA CONSTANTIN Institut de Chimie, SpectromCtrie de Masse Moderne, LA 31, 1 rue Blaise Pascal, 67000 Strashourg, France
RAYMOND HUEBER Institut de Chimie, Service de SpectromBtrie de Masse 1 rue Blaise Pascal, 67000 Strasbourg, France
Figure 1. Different shapes of the sample holder: (A) rod type; (B) shape used for the solutions: IC) 'snail' tvDe used for
References 1. E. Constantin, Y . Nakatani, G. Ouris-
son, R. Hueber and G. Teller, Tet- rahedron Lett. 4745 (1980).
2. E. Constantin, Y. Nakatani, G. Teller, R. Hueber and G. Ourisson, Bull. SOC. Chim. Fr. /I 303 (1981).
3. E. Constantin, B. Dietrich, M. W. Hos- seini, J. M. Lehn and R. B. Session, Proceedings of the 8th Mass Spec- trometry Conference, 18-19 June 1981, Elsevier, Amsterdam, in press.
4. R. 2. Cotter, Anal. Chem. 52, 1589A (1980).
5. D. Dessort and A. Van Dorsselaer, Tet- rahedron Lett. 1395 (1982).
solid state or the sample was dissolved in a suitable solvent and deposited with a solutions). V = Vespel; S= support. Received 11 January 1982
solid samples (may also 'be used for
460 ORGANIC MASS SPECTROMETRY, VOL. 17, NO. 9, 1982 @ Wiley Heyden Ltd, 1982
