Izotop-nisbati massa spektrometriyasi ( irms )

---

Izotop nisbatli
massa
spektrometriyasi
Izotop-nisbati massa spektrometriyasi (
IRMS ) - 
mass-spektrometriyaning
ixtisoslashuvi bo'lib , unda ma'lum bir
namunadagi izotoplarning nisbiy
ko'pligini o'lchash uchun mass-
spektrometrik usullar qo'llaniladi. 
[1] [2]

---

Ushbu texnikaning er va atrof-muhit
fanlarida ikki xil qo'llanilishi mavjud. "
Barqaror izotoplar " tahlili odatda tabiiy
tizimlarda massaga bog'liq bo'lgan izotop
fraksiyasidan kelib chiqadigan izotopik
o'zgarishlarni o'lchash bilan bog'liq .
Izotop nisbatli massa spektrometriyasi
Magnit sektor massa spektrometri issiqlik
ionizatsiyasi orqali izotop nisbatlarini tahlil
qilishda ishlatiladi .
Qisqartma
IRMS
Tasniflash
massa
spektrometriyasi

---

Boshqa tomondan, radiogen izotop tahlili
[3]
 tabiiy radioaktivlikning parchalanish
mahsulotlarining ko'pligini o'lchashni o'z
ichiga oladi va ko'pchilik uzoq muddatli
radiometrik tanishish usullarida
qo'llaniladi.
Kirish
CO 2
 ni o'lchash uchun izotop nisbati massa spektrometrining sxemasi

---

Izotop nisbati massa spektrometri
(IRMS) tabiiy izotoplarning
aralashmalarini aniq o'lchash imkonini
beradi. 
[4]
 Izotoplar nisbatlarini aniq
aniqlash uchun ishlatiladigan
asboblarning aksariyati magnit sektor
turiga tegishli . Ushbu turdagi analizator
ikki sababga ko'ra ushbu tadqiqot
sohasida to'rt kutupli tipdan ustundir .
Birinchidan, u bir nechta kollektorli tahlil
uchun o'rnatilishi mumkin, ikkinchidan, u
yuqori sifatli "cho'qqi shakllari" ni beradi.
Bu ikkala mulohazalar ham juda yuqori
aniqlik va aniqlikda izotop nisbatlarini
tahlil qilish uchun muhimdir. 
[3]

---

Alfred Nier tomonidan ishlab chiqilgan
sektor tipidagi asbob mass-spektrometr
dizaynida shu qadar ilg'or ediki , bu
turdagi asbob ko'pincha "Nier tipi" deb
ataladi. Umuman olganda, asbob qiziqish
namunasini ionlashtirish, uni kilovolt
diapazonidagi potentsialda tezlashtirish
va hosil bo'lgan ionlar oqimini ularning
massa-zaryad nisbati (m/z) bo'yicha
ajratish orqali ishlaydi. Yengilroq ionli
nurlar og'irroq ionli nurlarga qaraganda
kichikroq radiusda egiladi. Har bir ion
nurining oqimi " Faraday kubogi " yoki
multiplikator detektori yordamida
o'lchanadi .

---

Ko'pgina radiogen izotop o'lchovlari
qattiq manbani ionlash orqali amalga
oshiriladi, yorug'lik elementlarining
barqaror izotop o'lchovlari (masalan, H, C,
O) odatda gaz manbai bo'lgan asbobda
amalga oshiriladi. "Ko'p yig'uvchi"
asbobda ion kollektori odatda bir
vaqtning o'zida bir nechta izotoplarni
aniqlash imkonini beruvchi Faraday
stakanlari qatoriga ega. 
[5]
Measurement of natural variations in the
abundances of stable isotopes of the
same element is normally referred to as
stable isotope analysis. This field is of
Gaz manbalarining massa
spektrometriyasi

---

interest because the differences in mass
between different isotopes leads to
isotope fractionation, causing
measurable effects on the isotopic
composition of samples, characteristic
of their biological or physical history.
As a specific example, the hydrogen
isotope deuterium (heavy hydrogen) is
almost double the mass of the common
hydrogen isotope. Water molecules
containing the common hydrogen
isotope (and the common oxygen
isotope, mass 16) have a mass of 18.
Water incorporating a deuterium atom
has a mass of 19, over 5% heavier. The
energy to vaporise the heavy water

---

molecule is higher than that to vaporize
the normal water so isotope fractionation
occurs during the process of
evaporation. Thus a sample of sea water
will exhibit a quite detectable isotopic-
ratio difference when compared to
Antarctic snowfall.
Samples must be introduced to the mass
spectrometer as pure gases, achieved
through combustion, gas
chromatographic feeds,
[6]
or chemical
trapping. By comparing the detected
isotopic ratios to a measured standard,
an accurate determination of the isotopic
make up of the sample is obtained. For
example, carbon isotope ratios are

---

measured relative to the international
standard for C. The C standard is
produced from a fossil belemnite found
in the Peedee Formation, which is a
limestone formed in the Cretaceous
period in South Carolina, U.S.A. The fossil
is referred to as VPDB (Vienna Pee Dee
Belemnite) and has 
13
C:
12
C ratio of
0.0112372. Oxygen isotope ratios are
measured relative the standard, V-SMOW
(Vienna Standard Mean Ocean Water).