TCVN 7877-2008 -- IsO 5666-1999 - Chat Luong Nuoc - Xac Dinh Thuy Ngan

7/25/2019 TCVN 7877-2008 -- IsO 5666-1999 - Chat Luong Nuoc - Xac Dinh Thuy Ngan

1/21

TCVN T I U C H U N Q U C G I A

- - L - J -M - J .-I .. . . . . . .. t t........... I . . ......................... jm! -I^ .Ui l l fai i

TCVN 7877 : 2008ISO 5666 : 1999

Xut bn ln 1

CHT LNG Nc - XC NH THY NGN

Water quality - Determination o f mercury


2/21

TCVN 7877 : 2008

Li ni u

TCVN 7877 : 2008 thay th TCVN 5989 : 1995; TCVN 5990 : 1995

vTCVN 5991 : 1995.

TCVN 7877 : 2008 hon ton tng ng vi ISO 5666 : 1999.

TCVN 7877 : 2008 do Ban K thut Tiu chun TCVN/TC 147

Cht lng nc bin son, Tng cc Tiu chun o lng

Cht lng ngh, B Khoa hc v Cng ngh cng b.

3


3/21

TCVN 7877 : 2008

Li gii thiu

Trong cc ngun nc t nhin, cc hp cht thy ngn ni chung xut hin nng rt thp (nh

hn 0,1 ng/l). Cng c th nng cao hn, v d trong nc thi cng nghip. Thy ngn cng cth tch t trong trm tch v bn. Thy ngn xut hin dng hp cht v c v hu c.

phn hy hon ton tt c cc hp cht ca thy ngn, cn phi c qu trnh ph mu. Qu trnh

ph mu c th loi b ch khi chc chn o c nng thy ngn m khng cn x l s b.

i vi cc php o trong khong nng thp, iu cn thit l thuc th c tinh khit cao, bnh

phn ng sch, khng kh trong phng th nghim khng b nhim bn hi thy ngn v h thng o

phi rt n nh. Cc vn c th s yu cu qui nh thm iu kin b sung ngoi yu cu ca tiu

chun phi c nghin cu, xem xt.

iu quan trng l php th c tin hnh theo tiu chun ny c thc hin bi nhn vin c

o to ph hp.

5


4/21

T I U C H U N Q U C G I A TCVN 7877 : 2008Xut bn ln 1

Cht lng nc - Xc nh thy ngn

Water quality - Determination o f mercury

1 Phm vi p dng X

Tiu chun ny qui nh hai phng php xc nh thy ngn trong nc, v d nc ngm, nc mtv nc thi cng nghip.

Trong phng php nu iu 4, thic (II) clorua c dng nh l cht kh. Trong phng php nu

iu 5, natri tetrahydroborat c dng nh l cht kh. Vic la chn phng php ty thuc vo thit

b c sn v cc yu t cn tr (xem iu 3). c hai phng php ny u ph hp xc nh thy

ngn vi khong nng t 0,1 ng/l n 10 ig/\.Nng cao hn c th xc nh c nu mu nc

c pha long.

2 Ti liu vin dn *

Cc ti liu vin dn sau l rt cn thit cho vic p dng tiu chun ny. i vi cc ti liu vin dn

ghi nm cng b th p dng phin bn c nu. i vi cc ti liu vin dn khng ghi nm cng b

th p dng phin bn mi nht (bao gm c sa i).

TCVN 6663-1 : 2002 (ISO 5667-1 : 19801)) Cht lng nc - Ly mu - Phn 1 : Hng dn lp

chng trnh ly mu.

TCVN 5992 : 1995 (ISO 5667-2 : 19911)) Cht lng nc - Ly mu - Phn 2 : Hng dn k thut

ly mu.

TCVN 6663-3 : 2008 (ISO 5667-3 : 2003) Cht lng nc - Ly mu - Phn 3 : Hng dn bo qun

v x l mu.

3 Cc yu t cn tr *

Nguy c thay i phn ng c th xy ra trn thnh bnh, l qu trnh hp th v gii hp thy ngn

(xem 4.4).

1) ISO 5667-1 c phin bn nm 2006 thay th cho ISO 5667-1 : 1980 v ISO 5667-2 : 1991.

7


5/21

TCVN 7877 : 2008

Hdi thy ngn c th khuch tn qua cht do, cn ch hin tng ny khi chn vt liu lm bnh

cha. C th dng bnh thy tinh hoc bng cht do c bit nh perflo (etylen-propylen) (FEP). Bnh

Silicon ! khng ph hp.

Cc cht hu c d bay hi c th hp th trong di tia uv v c th nhm ln vi thy ngn. Cc cht

ny phn ln c loi b bng cch thm kali permanganat cho n khi dung dch c mu khngi v sc kh tr trong 10 min, trc khi kh hp cht thy ngn. Thng thng, cc cht cn tr do s

hp th c th c loi b khi s dng h thng b chnh nn.

Tt c cc dung dch phi c a vo nhit ging nhau (nh hn 25 C) trc khi kh v gii

phng hi thy ngn. C th trnh ngng t nc ln ca s cuvet bng cch sy nng cuvet, v d

dng n tia hng ngoi.

Cc cht cn tr c th xy ra do s c mt ca cc nguyn t khc trong hn hp ph thuc vo vic

chn cht kh. Nng cc nguyn t vt qu cc gi tr nu trong Bng 1 c th lm cho kt ququ thp.

Mt s t cc cht cn tr khc sinh ra t kim loi nng nu dng thic (II) clorua lm cht kh thay cho

dng natri tetrahydroborat. Khi s dng h thng dng chy, hiu ng cn tr do kim loi nng c th

gim i so vi cc gi tr nu trong Bng 1.

Bng 1- Nng c th chp nhn c ca mt s nguyn t' trong dung dch o, tnh bngmiligam trn lt

Cht kh

(nguyn t)

NaBH4

trc tip

NaBH4

trc tipSnCI2

trc tip

Trung bnh 0,5 mol/l HCI 5 mol/l HCI+0,2 g/l Fe (III)

0,5 mol/l HCI

Cu(ll) 10 10 500Ni(ll) 1 500 500Ag(l) 0,1 10 1

r 100 10 0,1As(V) 0,5 0,5 0,5Bi(lll) 0,05 0,5 0,5

Sb(lll) 0,5 0,5 0,5Se(IV) 0,005 0,05 0,05

Thic (II) clorua c th gy nhim bn thit b nu s dng natri tetrahydroborat sau . Do vy, cn c

h thng ring kh khi dng thic (II) clorua v dng natri tetrahydroborat.

Cnh bo - Thy ngn v hp cht ca thy ngn l rt c. Ht sc cn thn khi x l mu v

dung dch c hoc c th c thy ngn.

8


6/21

4 Xc nh thy ngn sau khi kh vi thic (II) clorua khng lm giu

4.1 Nguyn tc

Thy ngn ha tr mt hoc hai b kh thnh dng nguyn t bi thic (II) clorua trong mi trng axit.

Thy ngn nguyn t sau c loi khi dung dch bng dng kh tr hoc khng kh sch v cchuyn vo cuvet, theo dng kh nguyn t. o hp th bc sng 253,7 nm trong chm tia phng

x ca my o ph hp th nguyn t. Nng c tnh ton da trn ng chun.

4.2 Cn tr

CH THCH: Xem iu 3.

Nng odua >0,1 mg/l gy cn tr cho php xc nh do to phc thy ngn. Trong trng hp ny,

mt phng php khc nh kh bng natri tetrahydroborat (xem iu 5) l cn thit.

Do th oxy ha kh ca dung dch thic (II) clorua, cc hp cht thy ngn v c nh thy ngn sulfuav hp cht thy ngn hu c khng c kh hon ton khi khng tin hnh ph mu.

4.3 Thuc th

4.3.1 Yu cu chung

Ti thiu, s dng cc thuc th tinh khit phn tch hoc cc thuc th c hm lng thy ngn thp.

Nc phi l nc ct hai ln hoc c tinh khit tng ng. Hm lng thy ngn trong nc v

thuc th phi thp hn nng thy ngn thp nht phn tch c.

4.3.2 Axit nitric, p (HN03) =1,40 g/ml.

4.3.3 Axit sulfuric, p (H2S 04) =1,84 g/ml.

4.3.4 Axit clohydric, p(HCI) =1,16 g/ml.

4.3.5 Dung dch kali permanganat

Ha tan 50 g kali permanganat (KMn04), trong 1000 ml nc.

4.3.6 Dung dch n nhHa tan 5 g kali dicromat, K2Cr207l trong 500 ml axit nitric (xem 4.3.2) v pha long bng nc

n 1000 ml.

Cnh bo - Kali dicromat rt c. cn ch khi x l vt liu rn hoc dung dch ca chng.

4.3.7 Dung dch kali peroxydisulfat

Ha tan 40 g kali peroxydisulfat, K2s208, trong 1 000 ml nc.

4.3.8 Dung dch hydroxylamoni clorua

Ha tan 10 g hydroxylamoni clorua, NH4OCI, trong 100 ml nc.

TCVN 7877 : 2008


7/21

TCVN 7877 : 2008

4.3.9 Dung dch thic clorua

Ha tan 5 g thic (II) clorua ngm hai nc (SnCI2.2H20) trong 30 ml axit clohydric (4.3.4); pha long I

n 100 ml bng nc. i vi h thng dng chy, s dng dung dch c nng thp hn, v d 0,5 g

trong 100 ml. Chun b dung dch ny trong ngy dng t dung dch m c hn bng cch pha long

vi nc.

Nu kt qu mu trng (4.6) cao, loi ht vt thy ngn bng sc kh nit i qua dung dch trong

30 min.

4.3.10 Dung dch gc thy ngn I, p (Hg) =100 mg/l

Ha tan 108,0 mg oxit thy ngn (II), HgO trong 10 ml dung dch n nh (4.3.6); pha long n

1000 ml bng nc.

1ml dung dch ny c cha tng ng vi 0,1 mg thy ngn.

C th chun b dung dch gc I t dung dch tiu chun thy ngnc bn sntrn th trng.

Dung dch ny bn c t nht mt nm.

4.3.11 Dung dch gc thy ngn II, /?(Hg) =1mg/l.

Thm 10 ml dung dch n nh (4.3.6) vo 10 ml dung dch gc I (4.3.10) v pha long n 1000 ml

bng nc. 1ml dung dch ny c cha tng ng 1 g thy ngn.

Dung dch ny bn trong khong mt tun.

4.3.12 Dung dch tiu chun thy ngn (1), p (Hg) =100 g/l

Thm 10 ml dung dch n nh (4.3.6) vo 100 ml dung dch gc II (4.3.11) v pha long n 1 000 ml

bng nc. 1 ml dung dch ny c cha tng ng vi 100 mg thy ngn.

Chun b dung dch ny trong ngy dng.

4.3.13 Dung dch tiu chun thy ngn (2), p (Hg) =50 jg/I

Thm 10 ml dung dch n nh (4.3.6) vo 50 ml dung dch gc II (4.3.11) v pha long n 1 000 ml

bng nc. 1ml dung dch ny c cha tng ng vi 50 ng thy ngn.Chun b dung dch ny trong ngy dng.

4.3.14 Dung dch chun thy ngn

Chun b dung dch chun ph hp vi th tch v nng thy ngn ca php o dung dch mu

nh sau:

V d, i vi khong nng t 0,5 g/l n 5 g/l, tin hnh nh sau:

- dng pipt ht ln lt 1 ml; 2 ml; 4 ml; 6 ml; 8 ml v 10 ml dung dch tiu chun thy ngn (2)

(4.3.13) vo 6 bnh nh mc 100 ml;

10


8/21

- thm 1ml dung dch n nh (4.3.6) vo tng bnh nh mc 100 ml trn;

- lm y n vch mc bng nc v trn u.

Cc dung dch chun ny c cha tng ng 0,5 g/l; 1 |jg/l; 2 g/l; 3 |jg/l; 4 pg/l v 5 pg/l thy ngn.

Cc dung dich ny cn phi c chun b mi trc mi dy o. Nu cc php o chun phi tin

hnh h ln th cn chun b dy dung dch khc.

43.15 Dung dch thuc th trng

Chun bi th tch dung dch trng tng ng vi dung dch o bng cch thm 10 ml dung dch n nh

(4.3-6) cho 1 000 ml nc. S dng cng qui trnh ph mu nh i vi mu (4.6) v thuc th trng

ftong mi m phn tch.

4J .16 Dung dch ra dng c thy tinh

Thm khong 500 ml nc vo 150 ml axit nitric (4.3.2) v pha long n 1 000 ml bng nc.

4L4 Thit b, dng c

44.1 Yu cu chung

Mi dng c thy tinh trc khi dng phi c ra cn thn bng dung dch axit nitric (4.3.16) v trng

nhiu ln bng nc (4.3.1).

4.4.2 My quang ph hp th nguyn t c h thng monitoring. My cn c h thng b

chnh nn.

4.4.3 Ngun bc x xc nh thy ngn, v d n catot rng hoc n pht x khng in cc.

4.4.4 B hp th hi thy ngn (xem hnh 1) bao gm:

- ngn hp th gm c cuvet lm bng thy tinh bosilicat hoc thch anh, c ng knh trong khong

2 cm, chiu di t nht 15 cm (ph thuc vo thit b AAS) c hai u lm bng thch anh;

- bm lu thng kh (v d bm mng, bm nhu ng), cng sut 1 l/min n 2 l/min, vi ng bng

nha (h thng kn) hoc ng kh tr c van gim p (h thng h);

- lu lng k c ng nha (xem iu 3) (h thng h). i vi nng thy ngn cao, h thng h lu vit hn;

- bnh phn ng bao gm, v d, bnh y bng dung tch 100 ml, 250 ml hoc 1 000 ml nh s , c

nt nhm thy tinh, bnh ra bng thy tinh xp 1;

- ngun nhit ca ngn o, c th ngn cn s ngng t nc.

Nhit ca ngn o phi khng i trong sut qu trnh phn tch.

Hnh 1 a ra v d v mt h thng kn.

TCVN 7877 : 2008

11


9/21

TCVN 7877 : 2008

CH GII

1 Ngn hp th, ng knh trong 2 cm; chiu di 15 cm

2 Bm lu thng kh, cng sut 1 l/min n 2 l/min.

3 Nt thy tinh nhm 29/32

4 Bnh phn ng, dung tch 100 ml, 250 ml hoc 1000 ml.

5 Xp thy tinh

CH THCH 1: cn ch khi chn vt liu nha cho bm v ng dn (xem iu 3).

CH THCH 2: C th thay h thng dng chy lin tc bng h thng bm mu. cnthc hin theohngdn

ca nh sn xut.

Hnh 1 - B xc nh thy ngn dng thic (II) clorua (h thng kn)

4.4.5 Bnh nh mc, dung tch 100 ml, 200 ml v 1000 ml.4.4.6 Pipet, 1 ml, 5 ml v 10 ml.

CH THCH: Ngoi pipet, thun li hn dng thit b phn chia do nguy c nhim bn vt c th gim

ng k.

4.5 Ly mu v x l s b mu

Tin hnh ly mu theo TCVN 6663-1 (ISO 5667-1), TCVN 5992 (ISO 5667-2) v TCVN6663-3

(ISO 5667-3).

12


10/21

S dng cc bnh ly mu lm bng thy tinh bosilicat, thch anh, polysulfon (PSU) hoc fluorit etylen-

propylen polyme (FEP).

cn m bo rng cc hnh ly mu khng cha thy ngn hoc khng lm mt thy ngn do hp ph

ln thnh bnh.

hn ch s mt thy ngn do hp ph ln thnh bnh, v d thm 10 ml dung dch n nh (4.3.6) v

lm y n 1 000 ml bng mu.

Kim tra xem pH ca mu t khong 1v xut hin mu vng cam, iu ny cho thy d dicromat.

Nu cn, thm dung dch n nh v a h s hiu chnh th tch ph hp trong tnh ton kt qu.

4.6 Phng php ph mu bng kali permanganat/ kali peoxydisulfat

Tin hnh qui trnh ph mu vi thuc th t nh sau. cch khc, s dng mt trong nhng phng

php ph mu c nu Ph lc A, B v c nhng phi kim tra hiu sut cc phng php so viphung php ph mu t l tng ng nhau.

- Chuyn 100 ml mu nc n nh (xem 4.5) hoc mu c th tch ph hp (ti a 1000 ml) vo

bnh c lm t cc vt liu nu 4.5.

- Thm cn thn 15 ml dung dch kali permanganat (4.3.5), 1 ml axit nitric (4.3.2) v 1ml axt sulfuric

(4.3.3).

- Lc k hn hp sau khi thm.

- yn dung dch trong 15 min, sau thm 10 ml dung dch kali peroxodisulfat (4.3.7).

- t bnh c ng h nt vo ngun nhit hoc bnh cch thy v ph mu 95 c trong 2 h.

- Trong sut qu trnh ph mu, m bo rng lng kali permanganat lun m bo l d. Nu cn,

tng lng kali permanganat thm vo hoc bt u vi th tch mu t hn.dn

- dung dch ngui n nhit phng.

- Nu dng th tch mu khc nhau hoc th tch thuc th khc nhau, pha long ti th tch c th.

- Phn tch cng sm cng tt.

- Chun b dung dch thuc th trng theo cch ging nh i vi mu s dng th tch nc (4.3.1)

tng ng vi dung dich n inh (4.3.6) thm vo thay cho mu nc.gim

CH THCH: Permanganat c th gy nh hng i vi mu trng. Trong trng hp ny, cn gim nng

permanganat sao cho hm lng cht hu c l thp hoc s dng phng php ph mu khc (xem Ph lc A,

Ph lc B hoc Ph lc C).

63-34.7 Tin hnh

TCVN 7877 : 2008

13


11/21

TCVN 7877 :2008

4.7.1 Yu cu chung

Trc khi bt u qui trnh o, ci t cc thng s' ca my (4.4.2) theo hng dn ca nh sn xut

v iu chnh ngn hp th.

Nu dung dch thy phn c chun theo hng dn nu trong 4.6, ngay trc khi o, thm vo dung

dch thy phn (hoc hn, nu cn) 5 ml dung dch hydroxylamonium (4.3.8). Thng 5 ml dung dch

hdroxylamonium clorua l kh thuc th oxy ha d v hon tan ht kt ta oxyt mangan.

Nu sau 30 min, dung dch cha c trong th thm tip hydroxylamonium clorua.

Nu mt phn mu c ly phn tch, cn lm ti mt th tch c th, v d 200 ml.

Chuyn dung dch o (dung dch thu phn hoc dung dch pha long) vo bnh phn ngv ni

bnh vi thit b phn tch.

Thm 2 ml dung dch thic (II) clorua (4.3.9) cho mi 100 ml dung dch o.

Nu thuc th c thm bng tay, ni bnh phn ng vi thit b phn tch ngay sau khi thmdng

dch thic (II) clorua.

i vi th tch dung dch o ln hn (ti 1000 ml), cn tng th tch thuc th kh ti a 5 ml.

Trong h kn c bm khng kh, cho dng kh i qua bnh phn ng v ngn hp th tc 1 l/min

n 2 l/min, cho ti khi t c s hp th n nh.

Trong h h, lm sch dung dch o bng dng kh nn khng thu ngn hoc kh tr v o chiu cao

pic hoc din tch pic.

iu chnh lu lng dng theo hng dn ca nh sn xut v duy tr lu lng ny trong sut

php o.

o hp th ca dung dch xy dng ng chun (4.3.14) v dung dch thuc th trng (4.3.15) theo

cch nh i vi mu nc.

4.7.2 Phn tch bng phng php ng chun

Xy dng ng chun nh sau:

a) chun b dung dch xy dng ng chun thu ngn nh m t trong 4.3.14.b) o hp th ca dung dch xy dng ng chun v dung dch thuc th trng nh m t

trong 4.7.1.

c) thit lp cng thc i vi ng chun tuyn tnh t dy kt qu thu c.

4.7.3 Phn tch bng phng php thm chun

Vic s dng phng php thm chun c th b chnh c sai s do hiu ng cn tr, min l hp

th ca dung dch o thm chun nm trong khong lm vic tuyn tnh, cn m bo rng thu

14


12/21

TCVN 7877 : 2008

ngn thm vo tng ng vi th tch v hm lng thu ngn d kin ca mu. i vi th tch mu

50nv hm lng thu ngn d kin l 1 g/l tin hnh nh sau:

a) cho 50 ml dung dch o (4.7.1) vo bn bnh phn ng 100 ml;

b tim vo ba bnh ln lt 0,5 ml; 1,0 ml hoc 1,5 ml dung dch thu ngn tiu chun (1) (4.3.12).

Dung dch thm chun tng ng vi 1 pg/l; 2 |jg/l v 3 g/l thu ngn;

c| o nng thu ngn ca bn bnh theo hng dn trong 4.7.1;

d) vi dung dch trng (4.3.15), cng tin hnh theo cng qui trnh nh i vi mu nc.

4Lt Tnh ton

4J L1 Tnh ton bng ng chun

IM i nng thu ngn dng cng thc sau:

= z E li y ,

Trang

p l nng thu ngn trong mu, tnh bng microgam trn lt;

A l hp th ca hp th tng hp ca mu nc;

At l hp th ca hp th tng hp ca dung dch th mu trng;

b l dc ca ng chun v ca php o nhy, tnh bng lt trn microgam;

Vp l th tch ca mu dng chun b dung dch o, tnh bng mililit;

VMl th tch ca dung dch o, tnh bng mililit.

4-8.2 Tnh ton i vi phng php thm chun

Lp ng chun dng hp th o c ca dung dch o thm chun(4.7.3). Dung dch i

chng c chun b bng cch thm mu vo dung dch tiu chun v k c bc thm nng

m ngn.

Ghi li nng ca dung dch mu bng cch ngoi suy t ng chun vi hp th A =0. Xc nh

mong t nng thu ngn ca dung dch trng v tr i cc kt qu thu c i vi mu. Cch khc,

tn hnh nh gi bng hi qui tuyn tnh.

Cn tnh ton h s pha long khi cn thit.

4.9 Th hin kt qu

Bo co kt qu theo microgam trn lt v lm trn chnh xc n 0,1 g/l.

15


13/21

TCVN 7877 : 2008

V D: Thu ngn (Hg) 0,7 ig/I.

Thu ngn (Hg) 2,0 jag/i.

4.10 Bo co th nghim

Bo co th nghim cn phi vin dn tiu chun ny v bao gm nhng thng tin sau:

a) nhn dng y mu nc;

b) kt qu trnh by nh 4.9;

c) x l s b mu v phng php ph mu;

d)tt c cc chi tit khc vi phng php ny v mitnh hung c th nh hng n kt qu.

5 Xc nh thu ngn bng kh natri tetrahydroborat,khnglm giu mu

5.1 Nguyn tc

Thu ngn ha tr mt hoc hai c kh v dng nguyn t bng natri tetrahydroborat trong mi

trng axit. Thu ngn nguyn t sau c loi khi dung dch bng dng kh tr, di dng kh

nguyn t v cng hydro c gii phng, sau vo cuvet. hp th c o bc sng 253,7 nm

trong chm bc x ca my hp th nguyn t. Nng c tnh ton da vo ng chun.

5.2 Cn tr

CH THCH: Xem iu 3.

Nng niken >1 mg/l v nng bc >0,1 mg/ trong dung dch o gy cn tr vi vic xc nh thu

ngn. Dung dch st (III), niken ti 500 mg/l v bc ti 10 mg/l c mt trong axit clohdric pha long

vi nc t l 1:1 khng gy cn tr.

5.3 Thuc th

Ngoi cc thuc th lit k trong 4.3, tr dung dch thic (II) clorua, cc dung dch sau c yu cu

5.3.1 Dung dch natri tetrahydroborat

Ho tan 3 g natri tetrahydroborat, NaBH4v 1 g natri hydroxit, NaOH vo mt lng t nc. Pha long

bng nc ti 100 ml v lc qua giy lc.

Dung dch ny ch bn trong vi ngy.

Trong h thng dng chy lin tc, c th s dng nng thp hn, v d 0,02 g natri tetrahydroborat

v 0,03 g natri hydroxyt trong 100 ml nc.

Chun b dung dch ny trong ngy dng.

16


14/21

5-3-2 Dung dch m st

Ho tan 14 g st (III) nitrat ngm chn nc, Fe(N0)3.9H20 trong nc v pha long n 100 ml

bngnc.

Chun b dung dch hng ngy.

5l4 Thit b, dng c

5u4jI Thit b chit

Ptuong php ny sinh ra th tch ln hydro. Do vy, cn c thit b ny loib hydro.

5l4w2 My o ph hp th nguyn t (AAS) c h thng monitoring thchhp. Nn c h thng hiu

chnh nn.

5u4.3 Ngun bc x xc nh thu ngn, v d n catt rng hoc n phtx khng in cc.

4.4 B xc nh thy ngn, bao gm:

- ngn hp th gm cuvet lm bng thy tinh bosilicat hoc thch anh, ng knh trong khong

2 cm, chiu di t nht 15 cm (ph thuc vo thit b AAS)c hai ulm bngthch anh;

- ng ng kh tr (v d nit hoc argon) c van gim p;

- I/II lng k c ng dn bng nha;

- bnh phn ng v d bnh y trn hai c dung tch 100 ml hoc 250 ml,c nt thy tinh 29/32, bnh

ra v ng dn kh;

- ngun nhit cho ngn o, c kh nng ngn cn ngng t nc.

Nhit ca ngn o phi ging nh trong phn tch.

Hnh 2 nu ra v d v mt h thng h.

CH THCH 1: cn ch khi chn vt liu nha cho bm v ng dn (xem iu 3).

CH THCH 2: C th thay h thng dng lin tc bng h thng bm mu. cn thchin theo hng dn ca

nh sn xut.

TCVN 7877 : 2008

17


15/21

TCVN 7877 : 2008

CH GII

1 Ngn hp th, ng knh trong 2 cm; chiu di 15 cm

2 Dung dch NaBH4

3 Kh tr

4 Lu lng k

5 Bnh phn ng, hai c, y trn, 100 ml hoc 200 ml

Hnh 2 - B xc nh thy ngn vi natri tetrahydroborat (h thng h)

5.5 Ly mu v x l s b mu

Tin hnh theo qui trnh nu trong 4.5.

5.6 Phng php ph mu


5.7 Cch tin hnh

5.7.1 Bc chun b

a) Trc khi bt u qui trnh o, ci t cc thng s ca my (xem 5.4.1) theo hng dn ca nh

sn xut v t ngn hp th vo my.

b) Nu dung dch ph mu c chun b theo hng dn nu trong 4.6, ngay trc khi o thm vo

dung dch ph mu 5 ml (hoc hn, nu cn) dung dch hydroxylamonium clorua (4.3.8). Thng thng

5 ml dung dch hydroxylamonium clorua l kh lng thuc th oxy ha cn d v ha tan kt

ta oxit mangan. Nu sau 30 min dung dch khng c trong, thm tip dung dch hydroxylamonium

clorua.18


16/21

TCVN 7877 : 2008

O Nu lng mu nh c ly phn tch, pha long dung dch mu n th tch quy nh, v d

200 mi.

41 Thm 0,5 ml axit clohydric (4.3.4) cho 10 ml dung dch o vo bnh phn ng.

e) Chuyn dung dch o (dung dch ph mu hoc phn mu pha long) vo bnh phn ng vni bnh

v my phn tch (xem Hinh 2).

) vi 10 ml dung dch o, thm 2,5 ml dung dch natri tetrahydroborat (5.3.1).

i vi 50 ml dung dch o, thm 7,5 ml dung dch natri tetrahydroborat.

gt Nu dng dng kh tr, chuyn thy ngn vo ngn hp th. iu chnh lu lng dngtheo hng

dn ca nh sn xut v duy tr lu lng dng trong sut qu trnh o.

I Nu hm lng niken hoc bc trong dung dch mu cao (xem Bng 1), thm 25 ml axit clohydric

(3-4) v 0,5 ml dung dch m st (5.3.2) vo bnh phn ng trc khi thm 25 ml dung dch o. Nu

dng th tch lng o nh hn, pha long dung dch ny n 25 ml bng nc.

o dung dch chun (4.3.14) v dung dch trng (4.3.15) theo ng qui trnh nh i vi mu nc.

7.2 Phn tch dng phng php ng chun

Tin hnh theo qui trnh nu trong 4.7.2.

s.7.3 Phn tch dng phng php thm chun vo dung dch chun

Ten hnh theo qui trnh nu trong 4.7.3.

5u8 Tnh ton


5l9 Th hin kt qu

Tn hnh theo qui trnh nu trong 4.9.

5.10 Bo co th nghim


6 D liu chm

Php th lin phng th nghim c tin hnh c vo thng 1nm 1996. Kt qu c a ra trong

Bng 2.

19


17/21

TCVN 7877: 2008

Bng 2 - D liu chm

Tt c cc phng th nghim

Mau NAP%

Gi tr thc

pg/X

g/1 |jg/i

vc %


18/21

TCVN 7877 : 2008

Ph lc A

(tham kho)

Phng php ph mu bng siu m

A.1 Thit b b sung

A.1.1 L siu m iu chnh c nhit c cng sut t nht 240 W/I v kch thc ph hp vi

lch thc v s lng ca bnh ph mu.

A.1.3 Bnh ph mu bng thy tinh bosilicat hoc nha (v d polysunfon) c nt, ph mu

su m.

J L2 Ph mu

Chuyn 100 ml mu nc, c n nh theo 4.5, hoc th tch mu nh hn vo bnh ph mu.

Cn thn thm 1 ml dung dch kali permanganat (4.3.5), 1 ml axit nitric, 1 ml axit sulfuric (4.3.3) v 2 ml

kafi peroxodisulfat (4.3.7).

Lc k sau khi thm.

y cht nt bnh phn ng v t bnh vo l siu m 50 c trong 30 min.

dung dch ngui n nhit phng.

Nu dng lng mu v thuc th khc nhau, pha long dung dch ph mu ti th tch c th.

Phn tch cc dung dch ph mu ny cng sm cng tt.

Chun b v phn tch dung dch trng theo ng qui trnh, nhng dng lng nc (4.3.1) tng ng vi

dung dch n nh (4.3.6) thay cho mu nc.

21


19/21

TCVN 7877 : 2008

Ph lc B

(tham kho)

P hng php ph mu dng ni h'p

B.1 Thit b b sung

B.1.1 Chai ph mu, dung tch 100 ml, lm bng thy tinh pyrex khng mu c np vt bn

polypropylen hoc nt ph hp. Chai v nt chu c nhit 120 c v p sut 200 kPa.

B.1-2 Ni hp ph hp vi chai ph mu

Tnh chng chu nhit v p sut ca ni hp t nht cn phi bng vi nhit ca chai v c. N

hp cn c kim thot kh, van kh trng c th iu chnh cho thit b o p sut v ci t nhit . N

hp cng cn c thit b nhit hoc a nhit c b phn iu chnh.

B.2 Ph mu

Chuyn 40 ml mu nc, n nh nh m t trong 4.5, vo chai ph mu.

Thm 10 ml axit nitric (4.3.2).

ng cht nt chai v t chai vo ni hp.

un nng 120 c trong 30 min theo hng dn ca nh sn xut. I

ngui n nhit phng, v cho cht khng tan kt ta v dng cht lng trong phn tch,

Lc qua mng lc 0,45 JITI hoc ly tm mu sau khi ph mu.

Nu dng th tch mu v thuc th khc, th pha long mu n th tch c th.

Phn tch dung dch ph mu cng sm cng tt.

Chun b dung dch trng theo ng qui trnh, nhng dng lng nc tng ng (4.3.1) vi dung

dch n nh (4.3.6) thay cho mu nc.

22


20/21

TCVN 7877 : 2008

Ph lc c

(tham kho)

Phng php ph mu dng l vi sng

C.1 Thuc th b sung

CL1-1 Axit clohydric, /?(HCI) = 1,19 g/m.

c 2 Thit b b sung

C2.1 L v sng, c b phn t chng trnh nng lng sao cho nng lng c th phn b u

d io mau.

CH THCH: L vi sng phi chu c n mn v thng gi tt, sao cho hi axit b ht vo b phn ht hi. Tt

c i cc thit b in t phi c bo v khi s n mn trong khi vn hnh h thng mt cch an ton.

c ? ? Bnh nha, dung tch 100 ml, tng th tch xp x 140 ml, lm bng polytetraloetan (PTFE)

hoc perloalkoxy (PFA), c trang b van gim p/tr gip c kh nng chu c p sut khong

1 OOOkPa.

CH THCH: cn tun th nghim ngt hng dn ca nh sn xut.

Tin hnh

Chuyn 50 ml mu nc, n nh nh m t trong 4.5, vo bnh ph mu.

Thm 8 ml axit nitric (4.3.2) v 24 ml axit clohydric (C.1).

Lc trn v yn t nht trong 5 min.

ng cht nt bnh v t chai vo l vi sng.

Bt l theo qui trnh iu Chnh qui nh trong C.4.

Ly bnh ra khi l v ngui n nhit phng. Lm thng gi gim p qu cao (hp cha hi).

Nu dng th tch mu v thuc th khc, th pha long mu n th tch qui nh.

Phn tch dung dch ph mu cng sm cng tt.

Chun b dung dch trng theo ng qui trnh, nhng dng lng nc tng ng (4.3.1) vi

dung dch n nh (4.3.6) thay cho mu nc.

C.4 iu chnh l vi sng

iu chnh l vi sng l mt bc cn thit trc khi s dng. Qui trnh ny phi thit lp c cch iu

chnh nng lng cung cp thc s ca l vi sng (hiu sut).

23


21/21

L vi sng phi c iu chnh nh k. Vic iu chnh l vi sng ph thuc vo h thng in t m

nh sn xut ip t. Nu l vi sng c nng lng cung cp ph thuc tuyn tnh vi thang iu chnh

th c th hiu chun hai mc ci t (v d 40 % v 100 % nng lng). Tuy nhin, nn iu chnh

nhiu mc nng lng thit lp c tuyn tnh.

Nu thang ci t khng ph thuc trc tip vi nng lng cung cp, th cn iu chnh nhiu mcnng lng, cn phi tun th cc hng dn ca nh sn xut.

TCVN 7877 : 2008

24

Documents

TCVN 7877-2008 -- IsO 5666-1999 - Chat Luong Nuoc - Xac Dinh Thuy Ngan